Self-regulated learning is a cyclical process of forethought, performance, and self-reflection that has been used as an assessment tool in medical education. No prior studies have evaluated SRL processes for answering multiple-choice questions (MCQs) and most evaluated one or two iterations of a non-MCQ task. SRL assessment during MCQs may elucidate reasons why learners are successful or not on these questions that are encountered repeatedly during medical education.Internal medicine clerkship students at three institutions participated in a SRL microanalytic protocol that targeted strategic planning, metacognitive monitoring, causal attributions, and adaptive inferences across seven MCQs. Responses were transcribed and coded according to previously published methods for microanalytic protocols.Forty-four students participated. In the forethought phase, students commonly endorsed prioritizing relevant features as their diagnostic strategy  but few mentioned higher-order diagnostic reasoning processes such as integrating clinical information  or comparing/contrasting diagnoses . However, in the performance phase, students’ metacognitive processes included high frequencies of integration  and comparing/contrasting . In the self-reflection phase, 93% (n = 41) of students faulted their management reasoning and 84% (n = 37) made negative references to their abilities. Less than 10% (n = 4) of students indicated that they would adapt their diagnostic reasoning process for these questions.This study describes in detail student self-regulatory processes during MCQs. We found that students engaged in higher-order diagnostic reasoning processes but were not explicit about it and seldom reflected critically on these processes after selecting an incorrect answer. Self-reflections focused almost exclusively on management reasoning and negative references to abilities which may decrease self-efficacy. Encouraging students to identify and evaluate diagnostic reasoning processes and make attributions to controllable factors may improve performance. Learners who do not achieve proficiency at the expected level of training are a common challenge encountered by medical educators 23. Such 234Large-scale, multicenter studies of ways to help learners who underperform on medical knowledge tests are lacking and therefore most test-taking remediation is guided by expert opinion and institutional experience. Methods for improving test performance reported in the literature include diverse activities such as directed reading programs, completion of assigned practice questions and/or progress tests, problem-based learning, mandatory attendance at didactic conferences, neuropsychological testing, and regular meetings with faculty members 8910. How89SRL theory may provide a useful framework for conducting an individualized assessment aimed at identifying and remediating the deficits of underperforming learners . SRL is The focus of SRL processes often differ depending on the specific task at hand; for example, the strategies and metacognitive cues differ among a volleyball server, a free throw shooter, and a medical student trying to answer a practice question. Nevertheless, skillful self-regulation characterizes higher levels of human performance across a wide array of disciplines 1415. In 14Prior studies have utilized SRL microanalysis to describe the regulatory processes of medical learners engaged in preclinical neuroscience learning tasks , written1719Medical students at Uniformed Services University of the Health Sciences F. Edward Hébert School of Medicine, Georgetown University School of Medicine, and University of Central Florida College of Medicine were invited to participate. We chose to study clerkship students instead of preclerkship students because the clerkship provided a more uniform experience across the three institutions with 8-12 weeks of clinical internal medicine followed by the National Board of Medical Examiners Subject Examination in Medicine (NBME SEM). The study was initially designed as a randomized trial to test the effectiveness of a previously described intervention to improve test performance, with primary outcome of NBME SEM score as a primary outcome and secondary outcome of differences in self-regulatory processes during MCQs . No signAll students beginning the internal medicine clerkship at each site were invited to participate. Students were in their second or third year of medical school and entered the clerkship between September 2018 and December 2020. The preclerkship curricula at each institution were not identical but all complied with the standards of the Liaison Committee on Medical Education. As we sought to describe the SRL processes of students who were not the highest performers in medical school, participants were ineligible if they scored more than one standard deviation above the mean of the clerkship cohort (group of students starting the clerkship at the same time) on the NBME Self-Assessment in Medicine. To describe the study population, we collected participant age, gender, MCAT score, and NBME SEM score and percentile rank.To describe the regulatory processes of students engaged in answering MCQs, we developed an SRL microanalytic protocol according to methods previously described and administered to study participants at the end of the internal medicine clerkship . The pro1719To categorize the responses, two authors (MA and JM), with guidance from a third author (TC), developed a coding scheme based on a prior SRL microanalytic protocol used to assess medical students engaged in a clinical reasoning task . MA and The final coding scheme included categories for diagnostic reasoning, management reasoning, test-taking tactics, personal preferences, outcome-oriented statements, reliance on prior experience, case difficulty, luck, focus/effort, personal interest in topic/case, ability/knowledge, don’t know, and other. Diagnostic reasoning was subcategorized as basic diagnostic reasoning  and advanced diagnostic reasoning (integrating symptoms/signs and comparing/contrasting diagnoses). Management reasoning was defined as responses reflecting the need to identify the next best diagnostic test to order or therapy to initiate. Test-taking tactics were defined as responses referencing methods, approaches, or procedures for understanding and completing the test question and primarily pertain to actions or a plan for working through the test question as a test question rather than a diagnostic reasoning exercise .A full description of the coding scheme and definitions of categories is available in the Supplement. The frequency of codes for each SRL subprocess were tabulated and expressed as the number and percent of participants who gave a response corresponding to that code at least once over the seven practice questions. Given the importance of cognitive flexibility for success in medical school and higher education settings, we also calculated the proportion of students who changed their strategic approach after a failed attempt at a practice question and the proportion who maintained the same strategy in response to failure 25.Data on SRL microanalytic processes were gathered from 44 internal medicine clerkship students at three medical schools. Participants demographics are described in The frequencies of response categories for four microanalytic processes of strategic planning, metacognitive monitoring, causal attributions, and adaptive inferences are shown in Regarding strategic planning for the MCQ , betweenIn response to a question about metacognitive monitoring, or what the students were thinking about as they completed the test question, students continued to use basic diagnostic strategies such as identifying symptoms/signs , identifying contextual factors , and prioritizing relevant features . However, they were much more engaged with higher-level diagnostic reasoning processes than they had initially indicated when asked about their strategic planning before the question. While only 11% (n = 5) of students mentioned integrating clinical information as their strategic focus, 38 (86%) students gave metacognitive responses indicating that they were indeed engaged in integrating the clinical information as they worked through the practice question. As an example of a response indicating attempts at integration of clinical information as the primary metacognitive focus, one student noted, “[The patient] also has an elevated total bilirubin and elevated creatinine. Those two things in a patient with that history and elevated ammonia are already pointing me in the direction of a decompensated cirrhosis picture.” Likewise, while no students mentioned comparing/contrasting diagnoses as their chosen strategy, 24 (55%) students were indeed engaged in this technique based on their responses to the metacognitive monitoring question.  An exampMany student responses to the metacognitive monitoring question were coded in the management reasoning category . As an example of management reasoning, one student noted, when working through a problem about a patient with COPD presenting with failure of outpatient management, “Giving her six times a day of short-acting inhaler doesn’t sound like the way to solve this problem.” Another student, for the same vignette, noted, “She has an oxygen requirement, pretty significantly, with an unstable respiratory rate. So management-wise, thinking not sending her home.” Occasionally, students’ personal preferences for or against certain topics would emerge in their metacognition, such as when a student commented, “I hate pulmonary… absolutely hate it,” when asked what they were thinking about during the practice question on COPD. Additionally, 10 (23%) student responses were focused on negative references to their own knowledge or ability.Regarding causal attributions, which were queried whenever students answered a MCQ incorrectly, students rarely pointed to defects in their selected diagnosis or diagnostic reasoning process as the reason for their failure to answer a question correctly , metacognition (performance phase), and causal attributions and adaptive inferences (self-reflection phase) during the task of answering clinical vignette-style practice MCQs, a skill that is critical for achieving licensure and certification but as yet has not been examined using SRL microanalysis. In a study that allowed multiple opportunities to observe SRL processes in individual participants, a key finding was discordance regarding what students say they are focused on before a practice question, what they actually do in terms of diagnostic reasoning during a practice question, and what they reflect critically upon afterwards. Further, there was a subset of students who focused primarily on their poor skills and abilities during the task completing the activity, with an extremely large percentage of students  noting that their poor skills and abilities were the primary reason for their struggles. When medical educators can gain access to these types of student thoughts, strategic actions, and reactions to learning, they may be better equipped to provide feedback and coaching supports to these students .When examining each of the four regulatory processes in depth, interesting findings emerged. The strategic planning of students before they engaged in the practice questions included relatively few higher-order diagnostic reasoning strategies such as integration of clinical information or comparing/contrasting diagnoses, although students did identify simpler diagnostic reasoning strategies such as identifying symptoms/signs and prioritizing relevant features. However, even though higher order diagnostic processes were not an explicit focal point during the forethought phase, it became apparent during the performance phase when asked about metacognition that students are indeed engaged in integration and comparing/contrasting at a relatively high frequency. These findings suggest that the students in this sample did not proactively and intentionally think about the key processes that they would ultimately use during the diagnostic reasoning process. When medical students approach learning or performance activities from a reactive rather than proactive perspective, they will likely be less efficient in completing activities and will rely on social or normative comparisons to evaluate themselves rather than their personal progress .When it came to the self-reflection phase and students were asked about why they missed an answer  or what they needed to do better next time (adaptive inferences), students focused almost exclusively on management reasoning, while mentioning changes to their diagnostic approach less than 10% of the time. Students were relatively inflexible in their strategic approach, with most students maintaining the same strategy after making a mistake. Furthermore, nearly a quarter of student responses to the metacognitive monitoring question and 84% of attribution responses reflected negative thoughts about student’s own knowledge and abilities – a potentially distracting and maladaptive occurrence. Prior research has shown a relationship between attributing failures to factors outside student control (such as innate abilities) and declines in motivation and performance . OutsideOurs is the first study using SRL microanalysis to examine medical student regulatory processes during clinical vignette-based MCQs, a task that students must master to achieve licensure and certification. In addition, this is one of few SRL microanalytic studies across human performance domains that examined all three phases of SRL 21. In faOur results confirm some aspects of prior research and suggest potential targets for improving the quality of medical students’ strategic planning, causal attributions, and adaptative inferences. A prior study using SRL microanalysis in medical students working through a paper case also described a relative paucity of higher level diagnostic strategies in the planning phase, with only 15% (11/71) students indicating integration as a their strategy . SimilarIn our study, it was common for students to reference strategies related to test-taking tactics, or the mechanistic approach to an MCQ  in addition to or instead of a diagnostic reasoning strategy. This may indicate that students view success with these types of questions as arising from choosing the right test-taking tactic rather than applying the right diagnostic strategy. This presents an opportunity for educators working with students who seek to improve their test taking performance: namely, to reframe the MCQ as a diagnostic reasoning exercise. While there may be different levels of success associated with different mechanistic approaches to the question (top-to-bottom approach vs reading the question and/or answers first), these approaches have limited utility in clinical practice, where there is no list of answer choices provided with each patient. For students seeking to improve their performance, less emphasis on test-taking tactics and more on strategies to enhance the diagnostic reasoning process may benefit both test-taking performance and clinical practice.Cognitive flexibility, or the ability to change or reframe a perspective, has been positively associated with high achievement during college and medical school as well as lower rates of burnout 2526. In 25th national percentile on the NBME SEM and so results may not generalize to very low performers who may be most in need of improvement in their approach to practice questions. We did not further subcategorize management reasoning into task-specific or task-general processes, nor did we examine the effect of different types of MCQs which may be areas for future exploration and research. Our study was conducted during the COVID-19 pandemic which affected the educational experience of participants and may have affected our results. Finally, our study was not powered to examine associations between SRL subprocesses and academic outcomes.Our study’s strengths include its multicenter nature, the exploration of subprocesses in all three phases of SRL for a previously unexplored task of MCQs, and multiple iterations that allowed us to examine changes in strategy over the course of seven clinical vignette-based practice questions. As students spend a large proportion of their study time on these practice questions and as they are a common tool for assessing medical knowledge, it is important for medical educators to understand the cognitive and regulatory processes inherent to these questions. We have described patterns of strategic planning, metacognition, and attribution that may be maladaptive, such as the lack of explicit endorsement of diagnostic reasoning strategies as a focal point and lack of reflection on these strategies as reasons for failure, despite utilization of these strategies as evidenced by metacognitive inquiry, as well as a large proportion of negative thoughts about knowledge and abilities. These results are important for medical educators to consider as they seek to improve the regulatory processes and performance of poor test takers. Nevertheless, our study has limitations. Participants on average performed around the 28Our study adds to the growing body of literature that uses SRL microanalysis to explore regulatory processes in medical learners engaged in a variety of academic and clinical tasks 18192127.181921The additional file for this article can be found as follows:10.5334/pme.833.s1Supplement.The additional file includes the Question Review Form, a description of the SRL Microanalytic Protocol, and the SRL Microanalytic Protocol Coding Rubric.


PLOS Biology reveals an unexpected neuroanatomical complexity in these animals, also informing chordate origins.Hemichordates are close relatives of chordates. Their nervous system patterning is chordate-like, but their neural architecture remains unexplored. A new study in  Hemichordates, close relatives of chordates, have a nervous system that is chordate-like in its patterning but their neural architecture remains unexplored. This Primer explores a new study in PLOS Biology that reveals an unexpected neuroanatomical complexity in these animals. Acorn worms or enteropneusts (belonging to the phylum Hemichordata) are rather inconspicuous worms living as adults in muddy or sandy sediments in the oceans. Their body is fully ciliated and consists of an elongated, muscular proboscis followed by a narrow, constricted neck region and a rather short, fleshy collar, which continues into a worm-like trunk . Due to Saccoglossus kowalewskii and reveals the regionalised distribution and morphology of several neuron classes including intricate long-range projections [Molecular similarities in the expression of developmental genes have revealed striking similarities in nervous system regionalisation between hemichordates and chordates ,2. Despijections . The papThe diffuse organisation of the nervous system of acorn worms  stands iAnother puzzle that emerged from molecular studies of nervous system patterning in hemichordates related to the disparity between molecular coordinates and the underlying anatomy. While the expression of anterior–posterior patterning genes and the position and molecular makeup of brain signalling centres—such as the zona limitans intrathalamica and the isthmic organiser—is strikingly similar between hemichordates and chordates, there is no apparent similarity in the neuroanatomy that develops ,8–10.Saccoglossus kowalewskii to date. Their work combines conventional histological staining, labelling for neurotransmitter markers, dye filling, and the use of transgenic reporters. These approaches allowed them to characterise the detailed anatomy of several neuron classes, including the location of their soma, the morphology of dendrites and axons, and the distribution of putative synapses. One key finding was that several neuron types exhibit strong anteroposterior and dorsoventral concentrations. For example, several conserved neuropeptides show strong expression at the dorsal proboscis base, suggesting the presence of a neuroendocrine centre possibly releasing neuropeptides into the underlying coelomic fluid or circulatory system. Andrade Lopéz and colleagues also identified neuron types that distinguish the 2 nerve cords in the trunk. Glutamatergic neurons flank the dorsal cord, whereas histaminergic neurons mark the ventral cord, supporting early observations that the dorsal and ventral cords have different functions [What has been lacking to resolve these long-standing questions is more details of the anatomy of the hemichordate nervous system. Our knowledge of hemichordate neuroanatomy has still largely been based on classic investigations with a resolution that was not sufficient to reveal many individual neurons, neurite paths, or synapses . Andradeunctions .Neuronal labelling also revealed the detailed cell morphology of several neuron classes . The autOverall, the data suggest a hitherto unseen regionalization and complexity of the hemichordate nervous system. It is likely that the complex molecular regionalisation observed by gene expression analyses ,8 patterThe rich anatomical resource also helps to reinterpret early observations of acorn worm behaviour . The worThe study by Andrade Lopéz and colleagues revealed a hidden complexity of nervous system organisation in hemichordates hinting at a complex bilaterian brain under their skin with specific connections formed by a large number of neuron types with specific functions. This should attract new attention to these enigmatic animals and stimulate work on their behaviour, neuronal function, and wiring (connectome), also helping to reconstruct chordate origins.


Advancements in spatial transcriptomics (ST) have enabled an in-depth understanding of complex tissues by quantifying gene expression at spatially localized spots. Several notable clustering methods have been introduced to utilize both spatial and transcriptional information in the analysis of ST datasets. However, data quality across different ST sequencing techniques and types of datasets influence the performance of different methods and benchmarks. To harness spatial context and transcriptional profile in ST data, we developed a graph-based, multi-stage framework for robust clustering, called ADEPT. To control and stabilize data quality, ADEPT relies on a graph autoencoder backbone and performs an iterative clustering on imputed, differentially expressed genes-based matrices to minimize the variance of clustering results. ADEPT outperformed other popular methods on ST data generated by different platforms across analyses such as spatial domain identification, visualization, spatial trajectory inference, and data denoising.  •We developed a graph-based clustering tool for spatial transcriptomics data, ADEPT•ADEPT selects differentially expressed genes to perform imputation•ADEPT achieved robust clustering results with low variance•ADEPT improved accuracy over a range of existing methods Automation in bioinformatics; Data processing in systems biology; Transcriptomics Cell behavior is influenced by the surrounding environment, including signaling with adjacent and distant cells.,,,,,An important first step in ST research is to cluster the spots and define spatially coherent regions in terms of expression data and location adjacency. This is essential for downstream analyses, such as cell type or tissue annotation, new cell type identification, spatially variable gene identification, and gene ontology (GO) analysis.,Data quality across different ST sequencing techniques and types of datasets appear as a crucial factor that influences the performance of different methods and influences benchmarks. For example, previous studies with scRNA-seq data have attempted to solve the dropout effect, i.e. the large percentage of missing events or excessive zero counts,In this study, we were motivated to develop a robust clustering algorithm, called ADEPT, an Autoencoder with Differentially Expressed genes and imputation, by tackling the data quality effect across different types of ST data. ADEPT employs a graph autoencoder to learn the low-dimensional latent embedding of each spot via both gene expression and spatial context. To control and stabilize data quality, ADEPT relies on the selection of differentially expressed genes (DEGs) and imputation of the multiple DEG-based matrices for the initial and final clustering of the graph autoencoder backbone, to minimize the variance of clustering results. The DEG selection and imputation are performed multiple times and averaged for estimating robustness. We have benchmarked ADEPT against five other popular methods on ST data generated by different ST platforms to demonstrate its robustness and superiority in different downstream analyses such as spatial domain identification, visualization, spatial trajectory inference, and data denoising.,ADEPT is a multi-stage framework that performs spot clustering iteratively, and gradually increases clustering quality in an unsupervised manner, without the need for label information. Its overall pipeline is described in the following steps : There aTo evaluate the performance of our spatial clustering method, we used ADEPT on several annotated benchmark datasets, with five other tools. The accuracy and robustness of ADEPT were evaluated by using the adjusted rand index (ARI), Fowlkes–Mallows score (FMS), and purity, as well as comparing visualization of spatial domain identification between each tool and the ground truth. We also performed further downstream analyses such as spatial trajectory inference and ST matrix imputation for some specific datasets.We used datasets from the dorsal lateral prefrontal cortex (DLPFC), a human breast cancer dataset, and the STARmap dataset.The DLPFC dataset includes 12 human DLPFC sections, taken from three individual samples.For ADEPT, we used the Adam optimizerThere are two additional self-adaptive hyperparameters that need to be estimated in our framework. The first one is the minimum counts across cells per gene used in the data preprocessing step of ADEPT. In Another crucial hyperparameter is DEG lists kept after initial clustering. As we describe in the To quantitatively demonstrate the spatial clustering capability of ADEPT, we first tested it on two 10x Visium benchmark datasets which contain manual annotations as ground truth, the DLPFC dataset and the breast cancer dataset. Using the ground truth, we compared the clustering performance of ADEPT with five other recently developed spatial clustering tools .Further information and requests for resources and code should be directed to and will be fulfilled by the lead contact, Prof. Xin Maizie Zhou  10x Visium dataset,We design the graph attention autoencoder consisting of three core parts: the encoder, the decoder, and the graph attention layer.u. By treating expression profiles as the initial spot embedding, the u in layer l as follows:ε is is an exponential linear unit (ELU),u including u itself, v in the l for every node pair v towards learning a higher quality representation of node u on graphG. This is calculated by σ is a sigmoid activation function.The encoder’s input consists of the normalized gene expression profile and the edge lists. The encoder then generates node embeddings by aggregating information from all neighbors. We denote L-layer encoder u and represents the hidden embedding with the lowest dimension. The decoder attempts to reconstruct the normalized expression profile for each spot u  defined as:The output of the As mentioned in the section describing the overall pipeline of ADEPT, several differentially expressed gene (DEG) lists are selected from the initial clusters relying on a range of non-zero rates from 0.3 to 0.4. We chose this empirical threshold range to maintain an optimal number of DEGs. Within this range, ADEPT generates a specific number of DEGs and selects multiple DEG lists that meet the non-zero rate range threshold. Across this range of non-zero rates, ADEPT selects a small proportion of differentially expressed genes and determines if the data quality for each selection is acceptable. Across different types of datasets, we maintain the same range of non-zero rates, resulting in different DEG list selections for the next imputation step. ADEPT performs a Mann-Whitney U testThe ranks for each group are summed and these sums are used to determine the likelihood that gene expression among groups is different. This is performed using The minimum value between At this stage, ADEPT has selected several DEG lists based on non-zero rates and extracted multiple DEG-based matrices. We then impute these matrices and merge them for robust estimation, to minimize the variance of the final clustering result. The strategy of our imputation method is to use the average expression value of the gene within the same cluster and the pseudo-labels that are obtained from our initial clustering result to complete the dropout entries.g is the number of genes and c is the number of spots. The j. Specifically, we denote Additionally, we denote K DEG lists at least once.The imputed expression matrix contains all genes that occur in either of the Statistical details and software used for various types of data analyses in this work are cited in the appropriate sections in the


Editorial on the Research TopicFactors influencing user engagement with digital mental health interventionsDigital mental health interventions (DMHIs) are a promising solution to increase access to mental health support and overcome barriers to traditional mental health care, including costs  and stigFactors Influencing User Engagement with Digital Mental Health Interventions includes 8 articles to further investigate the various factors influencing user engagement and to what extent current DMHIs take these factors into account.This Research Topic on Using a variety of research methods, and focusing on a range of populations, this Research Topic presents new insights into factors that influence user engagement with DMHIs. For example, older adults may have little confidence or experience using technology , women fRaue et al. explored a message-based psychotherapy tool with 2,470 older adults and matched them with a cohort of younger adults aged 26–35 years to compare any differences in mental health improvements. They found that while cohorts did not differ in anxiety or depressive symptoms at the end of the study, younger adults experienced a quicker reduction in anxiety symptoms. Furthermore, older adults attended more days in treatment, but there were no differences between cohorts in app usage. McCall et al. conducted a focus group to inform the design of a mobile app tailored to Black women in supporting anxiety and depression. Recommendations were related to the type of content and features offered by the app, transparency about data and privacy, and creating a sense of community. Badawi et al. explored what factors facilitate user engagement with DMHIs among students and adolescents. They found different factors for frequent and infrequent users of DMHIs. Facilitators for frequent users included announcements about upcoming DMHI programs and having access to a variety of DMHI programs. Infrequent users wanted more concrete information about how DMHIs might help them and wanted to monitor their progress when completing DMHI activities.Simões de Almeida and Marques conducted a scoping review of 28 research studies to synthesize factors that may influence how people with schizophrenia engage with DMHIs. The authors identify a number of factors such as providing incentives to engage with the tool and reliability of content. Lastly, Moilanen et al. focused on members of the general public and found that people's personal prior experience with DMHIs affected their perceived trust in a chatbot. Overall, participants gave higher security and trust scores to a traditional web interface compared to a chatbot interface. These studies highlight the importance of understanding different user populations when developing and implementing DMHIs and considering their unique needs.Feijt et al. conducted a survey with 1,039 mental health professionals and asked about their use of digital mental health tools. In line with previous work (In addition to different types of end-users, mental health providers may have different perspectives on what is needed to facilitate DMHI adoption and engagement. Rickard et al. reviewed 91 DMHIs focusing on five areas: accessibility, integrity, clinical and research evidence base, user engagement, and interoperability. They found that only one DMHI fulfilled all these five evaluation metrics, indicating the need for more robust design and evaluation process in this domain.While user studies can provide insight into user needs that may affect user engagement, Balcombe and de Leo explored the opportunity to integrate mental health into existing technologies users may already use. In their opinion article, they focused on utilizing a music streaming platform for this purpose. The authors proposed that music platforms can be a useful platform to integrate with mental health, as listening to and creating music can reduce stress, anxiety, and depression. Furthermore, popular streaming platforms like Spotify already use their platform to host playlists and podcasts around mental health, which can reduce stigma around mental health help-seeking. The authors proposed to host the vetted digital mental health platform MindSpot on these streaming platforms in order to assess differences in mental health outcomes as well as user experience and link these outcomes with platform engagement and user behavior.People use a mixture of tools to support their health and well-being , and it Overall, the studies in this Research Topic highlight that: a one-size-fits-all approach may not work and designing for specific populations in ways that addresses their unique needs may increase acceptance and engagement; the COVID-19 pandemic has increased use and perceived value of DMHIS among mental health professionals and facilitated their intention for integrating DMHIs into their in-person care; not all publicly available DMHIs are of an equally high-quality standard, highlighting the need to hold app developers accountable to minimum-quality standards and for users and practitioners to assess whether DMHIs meet these standards; there is an opportunity to integrate mental health support into existing digital products.Researchers and developers can use these findings to inform development and evaluation of DMHIs to create meaningful tools and better understand the contextual factors that impact user engagement with these tools.


Spinal cord injury (SCI) is a major cause of disability worldwide and regenerative medicine offers hope for the development of new therapies for these injuries  Stem cell therapy is the current strategy for promoting neuronal regeneration in the spinal cord, but it faces significant limitations and challenges, such as low cell survival rates, tumorigenesis, and lack of integration into host tissue; (2) Clinical therapeutic approaches that promote neurological recovery for SCI are still limited; (3) The complex mechanisms and unusual difficulty of neural regeneration in SCI make it unlikely that a single method or strategy will achieve sufficient results to generate functional recovery.Continuous efforts are needed to explore new ways of generating functional recovery after SCI using current technology. While gene therapy for regeneration has been a hot topic in recent years, this technology is not yet well-suited for application in mammalian spinal cord regenerative models. In the next section, we propose a few different views of gene therapy that could offer a fresh perspective on regenerative medicine after SCI in mammalian.For over three decades, researchers have been investigating the potential of genetic modifications to provide long-lasting and potentially curative treatments for various inherited human diseases with a single intervention. In the context of SCI, gene therapy can be utilized to engineer cells that promote neuronal regeneration. This approach is typically employed post-injury or after a disease has manifested, aiming to enhance tissue repair and regeneration. For instance, Lu et al.  showcasein vivo gene expression reprogramming.Above studies highlight the promising role of gene therapy in fostering neuronal regeneration and functional recovery in the context of SCI. Typically applied after the onset of injury or disease, gene therapy aims to facilitate tissue repair and regeneration. Our focus is on the treatment of SCI through the use of nanostructured biomaterials and Nanoparticles have the potential to revolutionize the field of medicine by enabling targeted drug delivery and improving the effectiveness of therapies for a wide range of diseases, including SCI. Currently, there are limited treatment options available for patients with SCI, and most therapies focus on managing symptoms rather than promoting recovery. However, nanoparticle-based therapies hold promise for improving outcomes in patients with SCI.Nanoparticles offer a promising approach for delivering drugs or other therapeutic agents in the treatment of SCI. One such example is the CAQK peptide, which has demonstrated potential in treating CNS injuries due to its selective binding to chondroitin sulfate proteoglycans, which increase in expression following CNS injury , has been shown to improve neuropathic pain behaviors by decreasing dynorphin A release  enrichment is contributed by most cellular components close to the lesion epicenter for several months after injury, with CSPGs being the primary components of neural ECM  in regulating the proliferation and differentiation of neural progenitor cells into neurons during neurodevelopment. TFs are proteins that bind to DNA and control gene transcription. By reintroducing the expression of key TFs in glial cells in the spinal cord, researchers aim to reactivate neurogenic potential and promote neuroregeneration. SOX2 is a TF that maintains the identity of neural progenitor and stem cells. Recent studies have shown that SOX2 can reprogram astrocytes into proliferating neuroblasts, which can further differentiate into mature neurons with additional treatments. For example, Su et al.  used a lin vivo gene expression reprogramming can be challenging due to the numerous parameters that need to be optimized. These parameters may include the site(s) and timing for viral injection, the reprogramming factor(s) to use, the models of SCI, and the types of behavioral assays to perform. For instance, multiple injection sites may be necessary to reprogram a significant number of new neurons and achieve sufficient impact to facilitate functional recovery  in the early stages after SCI, gene therapy could be used to achieve several goals: reduce the formation of glial scars and immune responses to create a more favorable microenvironment for neuronal regeneration; (2) ectopic expression of potential TFs, such as SOX2, specifically activates regenerative genes in particular cell types; (3) potential TF genes could be delivered using nanoparticles, a non-viral delivery method, to different cell types such as NG2+ cells; (4) using a nanoparticle approach, inhibitory genes such as CSPGs could be knocked down to reduce lesion size and other negative effects, such as reducing the CSPGs produced by NG2, while increasing fiber sprouting; and (5) use gene editing to modify histone proteins, which regulate gene activity and affect the gene-regulatory machinery, to open condensed chromatin and expose potential regenerative genes. For example, Weng et al.  used CRITaken together, stem cell therapy could be combined with various gene therapies or biomaterials to further enhance the regeneration of damaged neurons. The future of neuronal regenerative medicine looks promising, with the potential for innovative therapies that could revolutionize the treatment of neurological conditions.in vivo gene expression reprogramming show promise in promoting neural regeneration and repair. Continued research into the molecular mechanisms underlying these approaches and optimizing parameters such as timing, dosing, and delivery methods could pave the way for more effective treatments in the future. With ongoing advancements in the field of regenerative medicine, there is hope for improved outcomes and better quality of life for individuals living with SCI.In conclusion, while regenerative medicine offers hope for the development of new therapies for SCI, significant challenges still need to be overcome. Current strategies face limitations such as low cell survival rates and lack of integration into host tissue. Nonetheless, innovative approaches such as nanostructured biomaterials and Therefore, our opinion is that continuous efforts are needed to develop safe and effective therapies, and to better understand the mechanisms that regulate neuronal regeneration in the spinal cord. We provide some future directions for neuronal regenerative medicine: (a) highlight the importance of comparative studies of neuronal regeneration in different vertebrate species to gain insights into the underlying mechanisms and to identify potential targets for promoting regeneration in mammals; (b) to address the current limitations and challenges in promoting neuronal regeneration; and (c) combining two different gene therapy approaches may offer a potential way to promote neuronal regeneration and improve outcomes for patients with SCI.Both authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.


The varicella-zoster virus can reactivate in patients with impaired cell-mediated immunity, resulting in herpes zoster (HZ) and sometimes in herpetic neuralgia (HN). Stellate ganglion blockade (SGB) has been studied for the treatment of HN and postherpetic neuralgia (PHN), but its effectiveness in preventing PHN in patients with acute HZ is not well-established. Here, we present a case of a 75-year-old woman who underwent SGB for HN of the right upper limb. The patient had been treated with antivirals and various analgesics, but adverse effects due to analgesics led to discontinuation of them. After the first application of SGB, the patient experienced significant pain reduction, and after a second application, complete remission of pain was achieved. Nine months later, the patient remained symptom-free and without PHN. The therapeutic potential of SGB in the treatment of HN and its role in preventing PHN requires further investigation. Varicella zoster virus (VZV) reactivation results in the infectious condition known as herpes zoster (HZ). Following the resolution of the initial VZV infection (chicken pox), the virus typically lays dormant in the sensory ganglia of the cranial and spinal nerves, but it can be reactivated in patients with impaired cell-mediated immunity due to advanced age or immunosuppressive medical conditions and malignancies .Herpetic neuralgia is a painful condition caused by this reactivation. It is a common complication of HZ and can be difficult to manage with conventional analgesics.It is known that the sympathetic nervous system plays a significant role in the pathogenesis of pain. Anatomic and chemical couplings between sympathetic postganglionic and afferent neurons may develop after nerve damage or tissue inflammation as a result of collateral sprouting in the peripheral and dorsal root ganglia and the upregulation of functional adrenoceptors . Given tStellate ganglion blockade (SGB) has been studied as a treatment for PHN, but its effectiveness in preventing PHN in patients with acute HZ is not well-established. Here, we present a case of a 75-year-old woman who underwent SGB for herpetic neuralgia of the right upper limb.The patient presented to our Pain Clinic suffering from herpetic neuralgia of the right upper limb at the distribution of C5-C6-C7 dermatomes, for one month after shingles rash Figure . From heIt was decided to perform SGB with the traditional approach based on anatomical landmarks according to the literature by identifying the sixth cervical vertebral tubercle (Chassaignac’s tubercle). This can be easily succeeded by locating the cricoid cartilage and moving the fingers until they contact this palpable tubercle Figure . The injPatient established Horner’s syndrome immediately  Figure . The patBlocking the sympathetic nerves in the head, neck, and upper extremity is a key way that SGB works to enhance blood flow to these areas. The treatment of sympathetically mediated pain in the head, neck, and upper extremity is also successful with SGB. The inhibition of neuronal connections in the sphere of innervation of SGB can be used to explain its analgesic effects . Many studies suggest that nerve blocks, specifically SGB, can be effective in preventing PHN in patients with acute herpes zoster. A systematic review and meta-analysis by Kim et al. found that nerve blocks significantly reduced the incidence of PHN compared to control groups . Chen etIn addition, Makharita et al. demonstrated that early SGB can reduce the incidence of PHN in patients with acute herpes zoster and facial pain . FinallyAccording to Aggarwal et al., for PHN of the face, neck, and upper limb distribution, SGBs with local anesthetics or its pulsed radiofrequency ablation (RFA) have been utilized successfully; nevertheless, their effectiveness is greater and longer-lasting if the PHN lasts less than a year .Postherpetic neuralgia can be safely and effectively treated using ultrasound-guided SGB and shock wave therapy, which can considerably reduce pain levels in patients with the condition. Ding et al. also suggest that treatment of facial and upper limb PHN with SG pulsed radiofrequency is secure and efficient. That is a procedure worth advocating for .Kim et al. published that PHN incidence is not reduced by SGB, however numerous blocks may have positive effects. Somatic blocks, including paravertebral and repeated/continuous epidural blocks, prevent and lessen the likelihood of PHN. Early nerve block may have stronger preventative effects when administered repeatedly or continuously than when given only once . Future Early management of infection and pain is likely to reduce the risk of postherpetic neuralgia. Treatment for this syndrome of chronic pain is challenging. The initial options are tricyclic antidepressants (amitriptyline) and antiepileptic medications . Interventional therapies, such as corticosteroid and local anesthetic injections into the epidural space, have an impact on the immediate pain but have minimal efficacy in avoiding postherpetic neuralgia. A sympathetic ganglion blockade may be attempted when conservative treatment for postherpetic neuralgia is unsuccessful in giving adequate relief. Spinal cord stimulation may be an option if severe pain persists .For selecting the single best interventional treatment, the available evidence is insufficient. Subcutaneous injection of botulinum toxin A or triamcinolone, transcutaneous electrical nerve stimulation, peripheral nerve stimulation, and SGB are advised initially, followed by paravertebral block and pulsed radiofrequency, considering invasiveness, cost, and safety .The oldest and most popular type of sympathetic block used today is SGB. Its applications range from PHN, intractable angina, complex regional pain syndrome (CRPS) ,13 hyperBased on these findings, nerve blocks, and specifically SGB, can be a useful intervention in preventing PHN in patients with acute herpes zoster affecting the head and upper limbs. Future research can further explore the optimal timing and frequency of nerve block interventions to maximize their efficacy in preventing PHN.To conclude, previous studies have shown that SGB can reduce the incidence of PHN in patients with HZ, although the quality of evidence is rated as low to moderate. The effectiveness of SGB in preventing PHN in patients with acute HZ is still not well-established, and more high-quality studies are needed to confirm its effectiveness. Nonetheless, our case report demonstrates the use of SGB in relieving pain in a patient with herpetic neuralgia of the right upper limb. The patient had previously tried multiple conventional analgesics, but none provided significant relief. The SGB procedure resulted in complete remission of pain and a sustained improvement in symptoms up to nine months later. This case report supports the use of SGB as a therapeutic option for managing herpetic neuralgia as well as the prevention of PHN in patients who do not respond to conventional analgesics. Healthcare providers should discuss the potential risks and benefits of SGB with their patients before considering this procedure.


The pathomechanisms through which heat stress interferes with pregnancy maintenance still remain vague, but emerging evidence underscores that the endocrine system is severely affected. It is well known that the endocrine system pivotally contributes to the physiological progression of pregnancy. We review – sometimes speculate - how heat stress can offset hormonal dysregulations and subsequently derail other systems which interact with hormones, such as the immune response. This may account for the heat-stress related threat to successful pregnancy progression, fetal development and long-term children’s health.Pregnant women are highly vulnerable to adverse environments. Accumulating evidence highlights that increasing temperatures associated with the ongoing climate change pose a threat to successful reproduction. Heat stress caused by an increased ambient temperature can result in adverse pregnancy outcomes,  ElevatePhysiologically, cortisol or respectively corticosterone levels depend on the secretion by the pituitary and adrenal gland. Both, the pituitary and the adrenal gland are affected by heat stress as indicated by increased organ weights in rats . ContradBased on a comparative study investigating the activation of the HPA axis in rats by various stressors such as fasting, crowding and extreme ambient temperatures, exposure to heat resulted in the highest plasma corticosterone level – the cortisol analog in rodents . Both, sVia a positive feedback on the maternal HPA axis, this results in a 40 fold higher CRH production from first trimester to term and a 3-5 fold rise in cortisol over gestation  at the beginning of pregnancy. hCG has a luteinizing effect on ovarian cells, which lengthens the lifespan of the corpus luteum and thus leads to sustained production of progesterone. At the moment there are no studies addressing the effect of heat exposure on hCG secretion.The derogation of successful reproduction caused by heat stress does not only manifest through placental alterations, but might also be linked to heat-triggered effects on the uterus. In fact heat stress has been shown to affect the morphology of the preimplantational endometrium, especially affecting the luminal epithelial cells, and triggering aberrant local cell proliferation as well as the dilation of the uterine glands . During Several studies reported some form of dysfunction in the female gonads upon heat exposure. Irregular phenotypes of granulosa cells accompanied by detachment of oocytes from the granular cell layer could be found in acute and chronic heat stressed mice , 27. Convia negative and positive feedback mechanisms, low hormone concentrations due to impaired production by the gonadal tissues have been proposed to lead to a decreased feedback response in the hypothalamus and the pituitary gland and stimulate the secretion of gonadotropins  axis functions otropins .Although estrogens are pivotal during pregnancy, few studies to date focused on the dynamics of estrogen levels throughout mammalian pregnancy in response to heat stress. One study dating back to 1982 failed to detect any heat-related alterations of free estrogens in chronic heat stress-exposed pregnant cows . HoweverBesides its pivotal role in establishing fertility and pregnancy maintenance, progesterone is also a thermal influencer. In contrast to estrogen, progesterone promotes heat conservation and higher body temperature . An incrComparable to the findings in non-pregnant mice, heat stress exposure of early pregnant mice led to a significant decrease in progesterone concentrations . ConcurrAnother explanation relates to the common progenitor of progesterone and cortisol: cholesterol-derived pregnenolone. Increased demand of cortisol in response to heat stress could lead to a competition of both syntheses and reduce progesterone availability .During the course of pregnancy, the maternal immune system undergoes gradual adaptations, which are essential to guarantee maternal tolerance towards the genetically foreign fetus. Dysregulation of these immunological adaptations is associated with pregnancy complications, such as recurrent spontaneous abortions, preterm birth or intrauterine growth restriction . HormoneGlucocorticoids such as cortisol are well known for their anti-inflammatory capacity. Additionally, they are involved in cell recruitment of macrophages to the feto-maternal interface as demonstrated in experiments with glucocorticoid receptor knock-out mice . AlthougStudies testing the direct effect of heat stress on immune cells during pregnancy are sparse. One study evaluating placental immune response to heat stress in late gestational mice described an increase in the expression of inflammatory genes . Here elAdditionally, the immune system may not only be acutely affected by heat stress, since long-term consequences have also been postulated. Triggered by the acute stress response, heat stress may lead to an acclimatization that enhances cytoprotective anti-oxidative and anti-apoptotic pathways against future stress exposure . This meIn addition to the discussed direct effects of heat exposure on hormone levels or immune homeostasis, heat may also indirectly modulate the endocrine pathways of HPG axis. Tropical nights   are assoClimate change poses a direct threat to mental health of pregnant women by favoring adverse pregnancy outcomes. Acute environmental events such as hurricanes, droughts or wildfires, and also chronic exposure to increased air pollution and high temperatures leads directly to mental health disorders such as posttraumatic stress syndrome or depression and indirectly by favoring water and food insecurities as well as migration . RecentlIn contrast to high temperatures, which directly affect thermoregulation, the indirect effect of heat in inducing an endogenous stress response – mirrored by heat-induced sleep deprivation and climate anxiety – must be taken into account, since this enhanced stress perception perpetuates the endocrine stress response in pregnant as well as non-pregnant individuals.via inducing cell stress, hereby inducing endocrine and immunological aberrations. Or whether heat stress simply functions as an external stressor, which activates the endogenous stress response, hereby activating the hormonal stress response cascade. In fact, both pathways can alter fetal and childhood development trajectories and affect the endocrine hemostasis of this next generation. Also, the impact of acute vs. chronic heat stress effects remains to be elucidated, and multifactorial risk assessments should be considered in order to control for possible confounder of heat stress, such as ozone and air pollution. The limited number of studies addressing these observations in animal pregnancy models or human pregnancy cohorts leave a blind spot to the vulnerable societal group of pregnant women. Given the rapid progression of climate change and cumulating weather extremes, it is of particular importance to intensify efforts of local research groups and global initiatives. However, to address these knowledge gaps, universal definitions of chronic and acute heat stress need to be established, to allow for comparison between studies (This review highlights the multifaceted consequences of heat stress on the endocrine balance and immune homeostasis, especially in the context of pregnancy. Clearly, many open questions remain before we fully understand how heat stress affects reproductive outcome. E.g., it remains to be tested if heat exposure directly affects the thermoregulation in pregnant women  studies Figure 4All authors contributed to the article and approved the submitted version.


Microraptor specimen. A survey of 92 feathered non-avian dinosaur and stem bird fossils did not find additional molting evidence. Due to its longer duration, in ornithological collections evidence of molt is found more frequently in extant bird species with sequential molts compared to those with more rapid simultaneous molts. The low frequency of molt occurrence among fossil specimens resembles collections of bird species with simultaneous molts. The dearth of molt evidence in the forelimbs of pennaraptoran specimens may have interesting implications regarding molt strategy during early avian evolution, and suggests that the yearly molting cycle may have evolved later, among crown birds.Feathers are a primitive trait among pennaraptoran dinosaurs, which today are represented by crown birds (Neornithes), the only clade of dinosaurs to survive the end Cretaceous mass extinction. Feathers are central to many important functions and therefore, maintaining plumage function is of great importance for survival. Thus, molt – by which new feathers are formed to replace old ones, is an essential process. Our limited knowledge regarding molt in early pennaraptoran evolution is based largely on a single  In this perspective, Kiat and O’Connor review non-avian dinosaur and stem bird fossils data and propose that annual molt evolved among Neornithes at a later point than early pennaraptoran dinosaurs. One interesting and important characteristic of feathers is that, unlike other keratin-based structures, full-grown feathers become incapable of growth or renewal. Therefore, the only way to renew a damaged feather is to replace it, which causes a temporary gap in the plumage3. The process by which new feathers are formed to replace old ones is called molt , are involved in many important functions. These include locomotion , thermoregulation, visual communication, camouflage, protection from solar radiation and parasites, and waterproofingolt Fig. , and likolt Fig. 4.Fig. 1P5, birds experience a single complete molt annually in which the entire plumage is renewed1. Most or all bird species seem to adhere to this roughly annual molt cycle, even in the tropics where molt may respond to annual rainfall regimes. There is little evidence for consistent molt cycles of more or less than a year in species of wild birds, although individuals may experience some variability between years. This fixed trait is most likely a result of the great importance of molt and the potential cost involved in avoiding plumage renewal. Due to the lack of variation among birds, nothing is known about the evolutionary development of this trait or when the annual molting cycle first evolved.In addition to partial molts that allow for breeding or seasonal differences in plumage in some species 6; all other evidence of growing feathers refers to young individuals exhibiting pre-juvenal molt9 which is not relevant here.In addition to the lack of variation among neornithines, the rarity of molt documentation in non-avian dinosaurs apparently also does not contribute to our understanding of the appearance of the annual molt cycle. To date, only one record of active molting among non-neornithine pennaraptorans has been identifiedHere, we propose that the rarity of molt evidence in non-avian dinosaurs and stem birds may hint at the evolutionary history of this trait. Specifically, we hypothesize that given complete randomness in our access to specimens, a correlation is expected between species-specific molt duration and the number of individuals that will be recorded in active molt out of a random pool of specimens. Taking a broader view, we predict that in a random sample of individuals belonging to species performing a sequential molt, a gradual replacement of the flight feathers carried out over an extended duration, we will find more individuals in active molt than in a sample of individuals belonging to a species performing simultaneous molt, which occurs over a shorter duration.Opisthocomus hoazin; n = 52 specimens), (2) Mourning Dove , and (3) Smooth-billed Ani , and three species have simultaneous molts (short molt duration): (4) Mallard , (5) Pied-billed Grebe , and (6) Purple Gallinule . For each specimen, we visually tested whether an active primary molt is present or absent. The results of this test corresponded to the prediction: the three species characterized by long molt duration  showed a significantly higher proportion of individuals in active molt compared to the three species characterized by short molt duration  of six bird species stored in the Field Museum of Natural History . Three species have sequential molts (long molt duration): (1) Hoatzin , but significantly differs from those three performing sequential and long duration molt .In order to examine this proportion among non-avian dinosaurs and stem birds, we tested a large sample of pennaraptoran fossils . Simultaneous molt most likely arose among large bodied taxa or those living in protected habitats, such as waterfowl, probably as an adaptation for reducing the duration of remex molt4. Thus, in contrast to the non-sequential (and non-simultaneous) molt, which has primarily evolved in some flightless species  and thus may have been common among early non-volant pennaraptorans, the simultaneous molt would not be expected to be very common among extinct volant taxa, and thus, this hypothesis is not very likely. Alternatively (2), non-avian pennaraptoran dinosaurs had a sequential primary molt but their molting cycle was longer than one year, i.e., the frequency of molt was lower than among extant birds. The result is that each individual spends less of its life time molting, and therefore, the proportion of individuals experiencing active molt from among a random sample of individuals will be low compared to species with an annual molting cycle . The second hypothesis may also be supported by the fact that feathers that appear highly abraded, as would be expected if molt was less frequent , are common in Cretaceous pennaraptoran fossils . However, we will qualify this by saying that our observations regarding feather abrasion is based on extant birds and the rate of feather abrasion in early taxa may have been different. It is also possible that what appears to be abrasion may in fact be the result of the fossilization process and not indicate in vivo plumage abrasion. Unfortunately, studies quantifying feather abrasion in birds are rare; thus, future research will be required to define comparable methods for measuring feather abrasion that can be used to compare modern birds and fossil specimens. Moreover, the basic premise presented here may be incorrect—it may be that our sample is not random and therefore does not correctly reflect the proportion of actively molting individuals in the entire population. Such a bias may arise in modern bird skin specimens as a result of the collector’s preference for non-molting birds which may be more perfect for exhibition and simpler to prepare. Similarly among fossils, if for example, individuals who avoid molting for some reason  tended to die and fossilize at a higher rate than their proportion in the real population, or if these specimens, which do not show active molt, died seasonally at a time that did not coincide with molt period, the result of both examples would be that molt would be underrepresented in our sample. However, at this time there is no evidence that indicates either sample is in fact non-random.We offer two possible explanations for these results. (1) Simultaneous molt was more common among pennaraptoran dinosaurs (including stem birds) than previously thought. Aerodynamic abilities inferred present in some non-avian dinosaur lineages and inherited by birds16 and additional fossils will shed new light on the subject discussed here and improve our understanding of basic avian life-history traits evolutionary processes.Our hypothesis suggests that the evolution of the flight feather annual molt evolved with the development of powered flight, among crown birds or a more derived subset of pennaraptorans , and as a response to the high dependence of this group on the flight feathers and the aerodynamic ability they impart. This strategy probably improves the ability to maintain high performance of the feathered flight surface in dinosaurs with true powered flight throughout the yearly cycle. The data gleaned from this statistical comparison of extant and extinct collections provides an intriguing hypothesis regarding molting in early pennaraptorans with limited flight capabilities. Further integration between ornithology neontological and paleontological dataDescription of Additional Supplementary FilesSupplementary Data 1


The fruit and seed produced by a small number of crop plants provide the majority of food eaten across the world. Given the growing global population, there is a pressing need to increase yields of these crops without using more land or more chemical inputs. Many of these crops display prominent ‘fruit–flowering feedbacks’, in which fruit produced early in sexual reproductive development can inhibit the production of further fruit by a range of mechanisms. Understanding and overcoming these feedbacks thus presents a plausible route to increasing crop yields ‘for free’. In this review, we define three key types of fruit–flowering feedback, and examine how frequent they are and their effects on reproduction in a wide range of both wild and cultivated species. We then assess how these phenomenologically distinct phenomena might arise from conserved phytohormonal signalling events, particularly the export of auxin from growing organs. Finally, we offer some thoughts on the evolutionary basis for these self-limiting sexual reproductive patterns, and whether they are also present in the cereal crops that fundamentally underpin global diets. A review examining how fruit produced early during reproduction can inhibit the formation of new fruit later in development, and why this may be advantageous for plants. There are some ideas that every gardener holds to be true. Ornamental flowers should be ‘dead-headed’ to keep them flowering. Pea pods should be promptly picked to promote production of further fruit. The ‘June drop’ will see some proportion of fruit falling from orchard trees, long before ripening. But conversely, if a tree is allowed to retain too much fruit, the tree might take a break from fruit production in the next year. The typical gardener is probably happy to ignore exactly how and why these effects occur. And yet, in formulating these guidelines, growers nevertheless seem to appreciate something fundamental about the coordination of plant growth and development—that different organs, at different times, can exert a profound inhibitory effect on the production or maintenance of other organs. Indeed, these inter-organ feedbacks are a critical component of the way in which plants organize their architecture so as to grow optimally in relation to resource availability in the environment, providing a developmental framework that is robust and yet highly flexible.The aim of this review is to explore these feedback-type mechanisms specifically in the context of reproductive development—to explore feedback that occurs between fruit and flowers, and how these allow plants to optimize their reproductive success in an uncertain environment. We will start by trying to define the types of feedback that occur, before considering the mechanisms that underlie these relationships, exploring their adaptive benefits, and assessing the prospects for using this information to improve crop yields.The production of fruit can have several potent effects on the reproductive effort of a mother plant. Since parthenocarpic (unfertilized) fruit can in many cases cause the same or similar effects as fertilized fruit, it is clear that fruit can exert significant feedback in their own right. However, fertilized fruit often have a stronger effect that parthenocarpic fruit ; they can initiate more floral primordia on existing inflorescences; or they can fully develop a larger number of the floral primordia   , flower for a considerably longer period than wild-type, and in the process, initiate more inflorescences than wild-type  in spring, the induction of flowering differs significantly between them. Flowering induction of deciduous trees usually occurs 80–90 d following anthesis of the previous generation of flowers, most likely due to endogenous developmental cues . InfloreThe effect of next-phase fruit feedback is clearly seen in cultivated fruit trees that have an ‘alternate bearing’ (AB) habit  varies greatly from tree to tree, and seems to be affected by many environmental parameters, but when trees of this species were planted in an experimental farm, their multi-annual productivity was quite stable, and they did not show a biennial bearing pattern (Pyrus pyraster) and wild olive showed clear biennial and non-regular bearing patterns (Carya illinoiensis) and macadamia (Macadamia tetraphylla and M. integrifolia) provide examples from recently domesticated fruit trees. In the wild, pecan displays masting and consistent with this, cultivated trees show strong alternate bearing behaviour. Conversely, in the wild, macadamia produces very low and non-regular yield, but when cultivated, the trees show relatively high and stable yield . FFF could theoretically be exerted at three scales: within inflorescences, between inflorescences on the same branch, and between inflorescences on different branches. In annuals, FFF can sometimes be observed at all scales, but in fruit trees FFF is mostly noticed and studied at the intra-inflorescence level and between inflorescences on the same branch. FFF has an important economic impact as it affects the overall number of fruit and it alters the ratio between small and large fruit, thus affecting yield .Cucurbits provide some of the most striking examples of FFF, with a single fruit often inhibiting the development of all subsequently initiated fruit, in both seeded and parthenocarpic varieties  inhibits the growth of other organs . ProbablLike many such arguments, the source–sink/dominance debate very likely represents a false dichotomy. There is no reason to doubt that the availability of assimilates within the plant will influence and limit the growth of organs. But equally, to suggest that the only way plants regulate their growth is by waiting to run out of assimilates is to do a disservice to these incredibly complex organisms. There is now a large amount of evidence that plants use long-distance hormonal signalling, among a range of other mechanisms, to coordinate their growth, and there is no reason to persist which such a simplistic model. Indeed, modern formulations of source–sink models for plant growth fully integrate active hormonal signalling  that would normally be prevented by fruit-driven feedback  might also play roles in controlling fruit-driven feedback, particularly in the complex effects of fruit load on flowering. Gibberellins, applied during the flowering induction period, are strong inhibitors of fruit tree flowering . The effCcMADS19 is a citrus orthologue of the floral repressor FLOWERING LOCUS C (FLC) from Arabidopsis, whose expression was shown to be reciprocal to that of the floral activator FLOWERING LOCUS T (FT)  in the CcMADS19 promoter consistent with increased activity, and—consistent with this—to have increased expression of TRITHORAX proteins that act as FLC activators in Arabidopsis , but there is a strong need for carpic dominance to allow selective shedding of excess fruit. Even with over-flowering and selective fruit-shed mechanisms in play, a wide range of reproductive success might result, and thus next-phase feedback allows plants to adjust their subsequent reproductive effort relative to the eventual success of the preceding reproductive cycle.By contrast, under-flowering is most appropriate in plants with a continuous reproductive effort, in which events early in reproduction can influence later events. An under-flowerer’s initial effort produces just enough flowers to guarantee minimum seed set if there is ‘perfect’ pollination, thus avoiding unnecessary investment in excess flowers and fruit. However, if pollination is not perfect, a lack of feedback from early fruit will promote the stepwise production of additional inflorescences or flowers to fulfil the minimum requirement (B. napus representing a ‘mild over-flowering’ strategy. Flowering in B. napus is continual and adjustable, but seems to contain a large initial effort that produces somewhat too many flowers, if all are successfully pollinated (B. napus to prevent too much fruit-set, but same-phase feedback is also present to allow the initiation of additional inflorescences if fruit-set is too low.There are of course a whole range of possibilities between these two strategies, with llinated . Carpic Feedback between fruit and flowering provides important insights into the mechanisms by which plants flexibly and continually adjust their shoot growth to match environmental conditions. As discussed above, very similar dominance mechanisms play a key role in the regulation of vegetative shoot architecture. Indeed, an appealing possibility is that all shoot and reproductive architecture is ultimately regulated by a single, unified dominance mechanism, or at least a suite of fundamentally similar dominance mechanisms. Recent work in pear illustrates how auxin export from leaves is necessary to maintain the paradormancy of autumn-initiated inflorescences (More generally, cereals crops represent an interesting opportunity in terms of fruit-driven feedback. There is no doubting the importance of fruit-driven feedback in commercial fruit trees and horticultural crops, but what about arable crops? Do they also display such feedback, and to what extent could applying the frameworks outlined here to cereals revolutionize our understanding of their yield formation? Mitigating fruit-flower feedback inhibition has long been a subject of intensive research in fruit trees. Numerous approaches have been developed to try and improve fruit tree yields, mostly based on plant growth regulators or alternation of sink–source relations (reviewed in


Although psychopathy is widely conceptualised as a mental disorder, some researchers question the maladaptive nature of psychopathy, and argue that it might be advantageous from an evolutionary point of view. According to this view, psychopathy can be seen as an evolutionary adaptative strategy that relies on deception and manipulation to gain short-term reproductive benefits. Psychopathy is also identified as a fast life strategy in response to early life stress and an adaptation to harsh environments. This paper investigates the evidence that psychopathic traits are adaptive, while also addressing the limitations of current evolutionary models of psychopathy based on frequency-dependent selection and life history theory. We review recent studies on the fitness correlates of psychopathy and find that psychopathic traits present potential adaptive trade-offs between fertility and mortality, and offspring quantity and quality. On a proximate level, individual differences in stress reactivity and environmental risk factors in early development predispose to psychopathy through gene–environment interactions. We propose that environmental, developmental, social and cultural factors can mediate the relationship between psychopathic traits and fitness and therefore should be considered to make accurate predictions on the adaptive potential of psychopathy. We end by outlining gaps in the literature and making recommendations for future evolutionary research on psychopathy. Social media summary: Can psychopathic traits be adaptive? Evolutionary perspectives should consider developmental, social, and cultural factors.1.Psychopathy is an inherently fascinating and controversial topic. This fascination is particularly evident when looking at the myriad of movies and true crime documentaries which have a psychopathic protagonist Hesse, . In turnAmong the prison population individuals with psychopathy account for a large proportion of severe and violent crimes  that encompasses core traits such as callousness and manipulativeness and an antisocial-lifestyle domain (factor 2) that entails disinhibition and chronic antisocial behaviour  explains inter-species variation in those traits as a result of environmental variation  and predicts trade-offs between different fitness components , most studies use fitness proxies such as mating and parenting behaviour . PsychopTo test the predictions from the LHT, several studies investigated the associations between early life environment, psychopathic traits and fitness proxies. In a community sample, individuals higher in the affective component of psychopathy which captures a lack of empathy had an especially strong relationship between childhood environmental harshness  and high mate seeking, short partner relationships and lower parental effort  is adequate to validate theories. Even if psychopaths engage in multiple sexual relationships, for example, that does not mean that they will have increased fitness as per number of children, compared with individuals who engage in few relationships with long-term commitments. Similarly, a psychopathic parent with lowered parental investment will not have reduced offspring fitness if the other partner compensates or there is adequate resource availability. Moreover, while psychopathic individuals might have abusive parenting styles, there is no considerable evidence that they will endanger the lives of their children. There is only one study to date that looks at nepotistic behaviours in psychopaths. Data from the case files of 289 violent males revealed that psychopathy predicts nepotistic inhibition of violent behaviour: as the PCL-R score increased, the relatedness between the offender and its victim decreased . Moreover, cultural variations in the expression of specific psychopathic domains of psychopathy  across cultures could imply that certain psychopathic traits are culture specific. However, such cultural differences could be suggestive of different rates of psychopathy or that psychopathic individuals inhibit their behaviours to comply with societal norms and to avoid ostracism.4.So far, we have reviewed evolutionary explanations of psychopathy, the evidence for and shortcomings of those explanations and the studies investigating fitness proxies of psychopathy. Throughout our review we have identified some limitations to the existing data, which in turn have led to the potential future directions below.Firstly, current evolutionary models of psychopathy often look at proxies of fitness such as increased mating effort or reduced parental investment. Nevertheless, such proxies may not always correspond to reproductive success. As we discussed earlier, the context in which interactions with psychopathic individuals take place can alter the fitness consequences of those interactions . More studies should investigate fitness outcomes using measures of fertility , fecundity  and individual and offspring mortality, as these have higher predictive value for reproduction and survival than behavioural proxies only. Additionally, the sample choice is important: post-reproductive individuals might provide the most accurate measure of fitness by assessing lifetime reproductive success  have a higher degree of adaptive functionality than factor 2 . For instance, factor 1 traits are associated with higher intellectual abilities and executive functioning than factor 2 traits  samples (Henrich et al., 5.Here we reviewed the evidence for and limitations of evolutionary explanations of psychopathy. Although there is some evidence for psychopathic traits presenting adaptive trade-offs between mate-seeking and fertility on the one hand, and mortality, morbidity and decreased parental investment on the other, they do not necessarily lead to straightforward consequences on fitness. At present most research is limited to proxies of fitness rather than measurable fitness outcomes, which limits our ability to test the evolutionary predictions. A more fruitful approach would require a move away from studies that only look at the correlation between psychopathy and fitness proxies, to a more integrated approach that considers proximate mediating factors and developmental triggers. The adaptive potential of psychopathic traits should be considered and assessed in relation to the social factors such as cultural norms, which might affect whether people tolerate, ostracise or are easily deceived by psychopaths.


Plastic pollution has emerged as a significant environmental concern in recent years and has prompted the exploration of innovative biotechnological solutions to mitigate plastic’s negative impact. The discovery of enzymes capable of degrading specific types of plastics holds promise as a potential solution. However, challenges with efficiency, industrial scalability, and the diverse range of the plastic waste in question, have hindered their widespread application. Structural biology provides valuable insights into the intricate interactions between enzymes and plastic materials at an atomic level, and a deeper understanding of their underlying mechanisms is essential to harness their potential to address the mounting plastic waste crisis. This review article examines the current biochemical and biophysical methods that may facilitate the development of enzymes capable of degrading polyethylene terephthalate (PET), one of the most extensively used plastics. It also discusses the challenges that must be addressed before substantial advancements can be achieved in using these enzymes as a solution to the plastic pollution problem. Plastics have become an integral part of modern life due to their versatility and low production costs. Conventional plastics are non-biodegradable which makes them a useful, durable material; however, in recent years the amount of plastic waste has become a mounting environmental concern. Their prolonged existence in the environment, notably marine ecosystems, is disrupting the delicate balance of the natural world and more recently the potential threat of microplastics to human health has been identified .Plastics are polymers composed of repeating units of small organic molecules with the majority manufactured from non-renewable fossil fuels. Their persistence within the environment is primarily attributed to their hydrophobic properties and the absence of hydrolysable functional groups in numerous plastics, including polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC). The polymer polyethylene terephthalate (PET) is one of the most prevalent plastics and has become a major contributor to plastic pollution; however, it has a susceptibility to degradation as it contains hydrolysable ester bonds .Evidence that enzymes can degrade polyesters dates back more than four decades . Since tIdeonella sakaiensis from a recycling plant which secretes two enzymes capable of degrading PET [In 2016, a research team isolated the bacterium The excitement surrounding the degradation of PET through the subsequent actions of PETase and MHETase has resulted in a surge of research publications detailing the three-dimensional crystal structures of these enzymes, offering valuable insights into their catalytic mechanisms. Similar to the cutinases, PETase employs a tunnel-shaped active site capable of accommodating PET. The catalytic triad of the enzyme has been identified , promptiI. sakaiensis, shares an α/β-hydrolase fold with PETase. However, crystal structures of MHETase bound to a non-hydrolysable substrate have revealed an additional lid domain that confers substrate specificity, reminiscent of a feruloyl esterase. Despite this, no residues within the binding pocket are conserved with feruloyl esterases, resulting in MHETase possessing a distinctive binding pocket tailored to accommodate the MHET substrate [MHETase, the second enzyme in the pair responsible for PET degradation in ubstrate . There iThe escalating issue of plastic waste has reached a magnitude where traditional methods of plastic waste management, including incineration and landfilling, can no longer effectively address the problem. The concept of a circular economy has been perpetuated by governments and campaigners which has motivated scientists to innovate sustainable solutions to plastic management. Among these, enzyme-enabled approaches provide a promising, more sustainable avenue by breaking down plastics into their constituent molecules, which can then be recycled or degraded further through natural processes. This review will focus on the structural understanding of PETase and how this has led to advancements in engineering this enzyme to enhance its catalytic activity, specificity, and stability.I. sakaiensis. One study reported a crystal structure of PETase at an unprecedented high resolution of 0.92 Å which allowed for extensive detailed structural comparisons between PETase and the cutinases which share considerable sequence homology [Extensive research has been conducted to investigate the molecular mechanisms of these enzymes from homology . PETase homology  hypothesDespite the technological advancements in structural biology over the last fifty years, capturing an enzyme-substrate complex, useful for analysing the catalytic mechanism, is still challenging. Due to the rapid hydrolysis by PETase, many groups attempted co-crystallization of PETase with various non-hydrolysable analogue of PET without success ,12 OtherAt the same time, the 21st century has witnessed the increasing application of computation in various scientific disciplines, including structural biology. While the emergence of Artificial Intelligence (AI) prediction tools, such as Alphafold2 and RoseTTAfold, has been met with both anticipation and criticism for their accuracy , computaTo elucidate the catalytic mechanism of the PETase, a recent study performed molecular docking simulations between the PETase and 2-HE(MHET)4, a molecule consisting of four MHET units that represent PET . The simA Trp185 residue can be located from the PETase crystal structure in Subsite I, proximal to the catalytic triad . This waThe structural investigations on PETase summarised above provide a comprehensive understanding of how these newly discovered enzymes may break down PET. However, in 2018, the United Nations estimated that annual global plastic production exceeded 400 million tonnes, with approximately 85% ending up in the landfill or unmanaged, meaning that it was left as uncollected litter or disregarded in unregulated sites on land or in water . PETase The application and scaling up of these enzymes have presented challenges due to their relatively slow reaction rates compared to the large amounts of plastic that need to be degraded on an industrial scale. However, it has been extensively documented that raising the temperature to the PET glass transition temperature (>65 °C) reduces the crystallinity of PET, allowing the enzymatic targeting of amorphous PET and thereby enhancing the rate of the hydrolysis process . Since PTm of 72 °C without depending on the addition of calcium but resulted in a 28% decrease in activity. To address this reduction in activity, molecular docking simulations were performed to identify sites for targeted mutagenesis. Combinations of these mutations were experimentally validated, and the resulting Phe243Ile/Asp238Cys/Ser283Cys (ICC) mutant was shown to restore catalytic activity to 122% of wild-type activity. A crystal structure of the ICC mutant reveals that Ile243 is located near the substrate-binding tunnel. This suggests that the mutant’s increased activity is due to an increased PET binding capacity [Rational engineering of these PET-degrading enzymes is being pursued with guidance from their three-dimensional molecular structures. It has been established previously that divalent ions have the capacity to increase the thermal stability of some hydrolases . A comprcapacity . The ICCcapacity . This raOne exciting research effort is the discovery of new enzymes, particularly sourced for naturally thermotolerant organisms. These enzymes not only further our understanding of how to create thermostable variants but also provide a better starting point before making structure-guided changes. In one study a total of 37 enzymes, originating from diverse phylogenetic groups, were identified . These eEnzymes are widely used in a range of other industrial applications, yet due to the recalcitrant nature of plastics, the development here has been limited. However, the improvement could have substantial applications in various sectors as incorporating enzymes into plastic degradation processes makes the process more sustainable and energy efficient compared to conventional mechanical recycling. This method of recycling applies force to break down plastic polymer length, compromising the polymer’s properties and restricting its potential applications. This practice, often termed ‘downcycling’, does not constitute true recycling, yielding products with limited utility in each iteration . HoweverOne major challenge is the need to engineer enzymes that can efficiently degrade a wide range of plastics beyond PET. Different plastic polymers possess distinct chemical structures and require specific enzymatic activities for degradation, yet a sample of plastic waste can contain a whole range of polymers. Therefore, efforts are underway to identify organisms and enzymes capable of targeting plastics other than PET, such as PS , PVC 2626 and PEAnother challenge lies in the scaling and cost-effectiveness of enzyme production. The industrial-scale production of enzymes requires the optimization of fermentation processes and the development of robust enzyme expression systems. Additionally, the cost of enzyme production must be competitive with traditional plastic waste management methods to enable significant adoption. Furthermore, the compatibility of plastic-degrading enzymes with existing plastic recycling infrastructure needs to be considered. Enzymes should not interfere with the quality of recycled plastic materials or introduce undesirable contaminants. Ensuring compatibility between enzyme-based degradation processes and existing recycling technologies is vital for the integration of enzymes into the plastic recycling process.If scientists and enterprises like Carbios can create a successful technology the potential could herald a revolutionary step towards the development of a circular economy. However, policymakers will require cost-effective methods before the widespread implementation of plastic-degrading enzymes.The problem of plastic waste is growing, and sadly, a significant proportion of the environmental burden arises not only from plastics that are properly recycled but from those that find their way into natural ecosystems. Raising the temperature in situ is, therefore, not a practical solution for tackling plastics outside of specialist facilities, despite the clear advantage that it increases the proportion of amorphous PET. Moreover, finding alternative methods to high temperatures used in industrial processes would decrease operational expenses and offer a more environmentally friendly solution to recycling as well.There are ongoing investigations into mesophilic organisms for their ability to operate optimally at lower temperatures . HoweverIn a study conducted in 2022, the objective was to engineer the hydrolytic activity of PETase at moderate temperatures, offering an alternative approach to developing a thermally stable enzyme . They acHowever, a significant challenge when researching and engineering these enzymes for industrial or environmental use lies in the extensive range of crystallinity present in plastic waste. Current experimental set ups in the existing literature often use standardized PET with specific crystallinity levels that are lower than the diverse crystallinity found in real-world plastic waste. Many studies initially validate their findings using only amorphous PET, which is not representative of the plastic problem, thus limiting the applicability of the results to real-world scenarios.When assessing these engineered enzymes, it is crucial to test them on samples intended for recycling. The study investigating FAST-PETase used a variety of post-consumer plastic waste samples with controlled variations in crystallinity and compared the results with other thermotolerant PETase mutants in addition to the wild-type . Their sThe recalcitrant nature of many plastics can be attributed to their hydrophobicity and insolubility which heavily reduces their biodegradability. Considerations to reduce the impact of this in waste management include Ultraviolet irradiation to increase the number of hydroxyl groups thus improving the surface properties for bio degradation . For othAn alternative approach under consideration is from the cellulase research community where the multi-modular architecture of cellulases, consisting of both a catalytic module and a carbohydrate-binding module, is well established. This modular design creates a synergy that significantly increases the catalytic efficiency of these enzymes . This haI. sakaiensis, shares a similar structure with PETase. As expected, the degradation of plastic using both enzymes was faster compared to PETase alone and no activity was observed for MHETase alone. Excitingly, the researchers went on to create a chimeric PET-MHET dual enzyme, which improved the hydrolysis rate by more than threefold [Other multi-modular systems are also being investigated. It has been demonstrated that MHETase, the second of the pair of PET-degrading enzymes from hreefold . This suInterestingly, the cellulase research community is conducting extensive research on the cellulosome, an extracellular multi-enzyme complex that significantly enhances cellulose degradation . This reThe concept of a circular closed economy is often discussed as the objective to work towards the future. Governments and advocates have perpetuated the idea of a circular economy, inspiring scientists to develop sustainable solutions for plastic management. Start-ups like Carbios are making paths for technological development but other organizations are looking to collaborate with the global picture in mind. Revolution Plastics, based at the University of Portsmouth (UK) , is an oA groundbreaking announcement was made in May 2023 by the Intergovernmental Negotiating Committee, revealing plans for an innovative plastics treaty set to be enforced by 2025 . This reIn this review. we began by assessing our current understanding of how PETase functions and we found ourselves both surprised and perplexed by the apparent evolutionary deviations that have set these enzymes apart from their cutinase counterparts. PETase has clearly retained the overall α/β hydrolases structure yet subtle adjustments, like the ‘wobbling’ Trp residue, have occurred to accommodate the PET substrates. However, multiple studies show that this can be pushed further to create faster variants than the wild type and as our grasp of how altering PETase potentially improves the rate, we could apply this to tackle a spectrum of enzymes. The rise of computation and AI models may also help us uncover the patterns that nature seems to follow yet improvements may rely on directed evolution to truly enhance these enzymes’ efficiency.Over the past decade, efforts to create an enzyme with the capacity to degrade crystalline PET without the need for additional pre-treatment and temperature increase have proven futile. While this may be of lesser concern within industrial applications, the question arises: Can an enzyme be effectively deployed in natural ecosystems to counter the growing impact of microplastics? A clearer approach may involve establishing proper tracing and accountability mechanisms for plastic production while simultaneously racing to discover more effective enzymatic solutions within industrial waste management. The success of such methods would alleviate not only environmental pollution but also the potential unintended consequences and ethical assessments necessary before using these enzymes in natural ecosystems.However, effectively addressing plastic waste comprehensively demands the exploration of various enzymes for the biodegradation of other synthetic polyesters like nylon and PVC. Understanding the molecular intricacies of the PETases has been a first step in harnessing the potential enzymes for plastic degradation yet other more hydrophobic plastics may provide a greater challenge. Combining PETase with other plastic-binding domains or even creating multi-enzyme complexes could alleviate some of the pressure on solely enhancing the PETase itself to increase the degradation rate. Instead, these methods could focus on enhancing the degradation processes, alternatively to just the PETase mechanism. Drawing inspiration from other fields where nature has developed techniques to break down resilient polymers, such as cellulose, might provide valuable insights. Given that plastics are relatively new materials, having been mass manufactured only in the past century, natural evolution has not had sufficient time to develop its own solutions for their decomposition. Intervening and utilizing existing mechanisms could potentially offer the necessary solution to address this challenge.A profound level of collaboration involving researchers, policymakers and environmental organizations will play a pivotal role in guaranteeing the allocation of funding for pertinent research and facilitating innovation in this domain. The prospect of engineering enzymes to address our waste presents an alluring opportunity that could significantly contribute to safeguarding our planet. However, the obstacles of efficiency, scalability and versatility remain unresolved challenges that must be overcome before the issue escalates to an irreversible place.