The midline and intralaminar nuclei of the thalamus form a major part of the “limbic thalamus;” that is, thalamic structures anatomically and functionally linked with the limbic forebrain. The midline nuclei consist of the paraventricular (PV) and paratenial nuclei, dorsally and the rhomboid and nucleus reuniens (RE), ventrally. The rostral intralaminar nuclei (ILt) consist of the central medial (CM), paracentral (PC) and central lateral (CL) nuclei. We presently concentrate on RE, PV, CM and CL nuclei of the thalamus. The nucleus reuniens receives a diverse array of input from limbic-related sites, and predominantly projects to the hippocampus and to “limbic” cortices. The RE participates in various cognitive functions including spatial working memory, executive functions  and affect/fear behavior. The PV receives significant limbic-related afferents, particularly the hypothalamus, and mainly distributes to “affective” structures of the forebrain including the bed nucleus of stria terminalis, nucleus accumbens and the amygdala. Accordingly, PV serves a critical role in “motivated behaviors” such as arousal, feeding/consummatory behavior and drug addiction. The rostral ILt receives both limbic and sensorimotor-related input and distributes widely over limbic and motor regions of the frontal cortex—and throughout the dorsal striatum. The intralaminar thalamus is critical for maintaining consciousness and directly participates in various sensorimotor functions  and cognitive tasks involving striatal-cortical interactions. As discussed herein, while each of the midline and intralaminar nuclei are anatomically and functionally distinct, they collectively serve a vital role in several affective, cognitive and executive behaviors – as major components of a brainstem-diencephalic-thalamocortical circuitry. As well recognized, the thalamus is the gateway for the transfer of modality-specific information from principal (or first order) thalamic nuclei to distinct (sensorimotor) cortical targets. In the same manner, the thalamus is a conduit for the transfer of affective and cognitive-related or limbic) information to distinct regions of the cortex which process this type of information—or limbic cortices. Accordingly, the thalamic nuclei which serve this function are generally recognized as constituting the “limbic thalamus”. Whereas, schemes may differ, the “limbic thalamus” is thought to mainly consist of the anterior nuclei (ATN), the mediodorsal nucleus (MD), the submedial nucleus, the intralaminar nuclei (ILt) and the midline nuclei  nuclei, the association nuclei, and the midline and intralaminar nuclei Jones, ,b. The pThe “association” nuclei are a largely ill-defined group that differ from the principal nuclei in that they do not receive direct sensory  or motor information and essentially do not project to primary sensorimotor cortices. The association nuclei receive major input from layer 5 pyramidal cells of the sensorimotor cortex and relay this information to associational areas of cortex—hence association nuclei of thalamus. The association thalamic nuclei include MD, the anterior nuclei, the submedial nucleus (SMT), and the lateral nuclei .The midline and intralaminar thalamic nuclei form a separate group primarily based on: (1) their distinct location along the midline and within the internal medullary lamina; and (2) and their relatively widespread distribution throughout the cortex. The intralaminar (ILt) nuclei consist of the central medial (CM), paracentral (PC), central lateral (CL), of the rostral ILt and the parafascicular (PF) and subparafascicular (SPF) nuclei of the posterior ILt. The midline nuclei include the paratenial nucleus (PT), paraventricular nucleus (PV), rhomboid nucleus (RH) and the nucleus reuniens (RE)—and in some classifications the intermediodorsal (IMD) nucleus.The midline nuclei are characteristically divided into two main groups along the dorsoventral axis: the dorsal midline nuclei consisting of the paraventricular (PV) and paratenial (PT) nuclei and the ventral midline nuclei consisting of the rhomboid (RH) and reuniens (RE) nuclei. Presently, we focus on the circuitry and functional properties of RE and PV of the midline thalamus and the central medial nucleus (CM) of the rostral intralaminar complex in rodents .As stated, the ventral midline thalamus consists of the RE and RH. While RE and RH projections are similar/overlapping, few studies have examined the functional properties of RH independent of RE. As such, we focus on RE. We first describe the circuitry of RE and then its functional properties.RE receives a vast and diverse array of afferent projections from the cortex, hippocampus, basal forebrain, amygdala, hypothalamus and brainstem Vertes, . SpecifiIn accord with findings in the rat . With the possible exception of the entorhinal cortex, each of these cortical regions are sources of afferent (return) projections to RE , indicatThe major efferent targets of RE are the hippocampus (HF) and limbic (neo) cortices. RE distributes prominently to the IL, PL, and anterior cingulate (AC) cortices of the mPFC , but alsAs described in several reports, RE distributes massively, and in a highly organized manner, to the hippocampus. Specifically, RE fibers to the HF terminate selectively in the stratum lacunosum-moleculare (slm) of CA1 of the dorsal and ventral HF and in the molecular layer of the subiculum (SUB) and parasubiculum . RE axonvia collaterals, to the HF and mPFC – mainly concentrated laterally in RE, just medial to the lateral wings of RE. Although RE cells projecting to single sites  were intermingled throughout RE, those distributing to the mPFC were mainly located in the lateral wings of RE, while those projecting to the HF were most numerous in the rostral pole of RE. Interestingly, RE projections to the ventral HF were ~10-fold greater than those to the dorsal HF . In this regard, Schlecht et al.  recentlyRE is reciprocally connected with the HF and several limbic cortical sites, prominently the mPFC, and is a major intermediary between the HF and mPFC   of RE in spatial WM remains unclear; that is, is the involvement of RE in WM linked to the encoding, retrieval or long term retention of spatial information? Specifically, Maisson et al.  using a In summary, working memory critically involves interactions between the HF and the mPFC, and as recently demonstrated, RE represents a vital link between the HF and the mPFC in working memory. Accordingly, the inactivation of RE disrupts both synchronous oscillations between the HF and mPFC and performance on working memory tasks as well as long-term memory processing.Whereas, RE's involvement in SWM has been extensively examined  with behavioral flexibility is often examined in animal models through reversal learning or compulsive behavior   fear to aspects of the environment.In a similar manner, Ramanathan et al.  showed tMoscarello  describevia the RE”.Maren et al.  in mice. Complementing this, Linley et al.  regions of RE, it is clear that, as major interface between the HF and medial/orbital PFC, nucleus reuniens is intimately involved in the affective and cognitive functions served by these cortical structures.As stated, the dorsal midline thalamus consists of the PV and PT. PV is located medially below the third ventricle and dorsomedial to MD, and essentially spans the rostro-caudal extent of the thalamus. PT, however, is a rather small nucleus which lies lateral to PV at the rostral pole of the thalamus. Whereas, the projections of PV and PT significantly overlap , the medial preoptic area (MPO) and the diagonal band nuclei , the pontomesencephalic RF, nucleus cuneiformis, the dorsal and median raphe nuclei, the PAG, the parabrachial complex (PB), the laterodorsal (LDT) and pedunculopontine (PPT) nuclei, the locus coeruleus (LC) and the solitary nucleus (NTS)  cells in PV—about 7–17% per combinations of injection. Particularly striking was prominent PV projections to the shell of ACC; that is, ~80% of PV neurons were retrogradely labeled following dual injections in the dorsomedial and ventromedial shell of ACC and about 10% of them were double labeled—indicating collateral PV projections to both shell regions of the ACC. The anterior PV was shown to strongly target the dorsomedial shell of ACC and the posterior PV, the ventromedial shell of ACC. In like manner, tracing the axonal trajectory of individual PV neurons, Unzai et al.  and posterior PV (PVp), with correspondingly differential effects on the ACC in the control of feeding. Specifically, it has been shown that the activation, or alternatively the suppression of PV can promote feeding, likely Early evidence favoring the activation of PV in feeding stemmed, at least in part, from the demonstration that PV is a major recipient of orexin fibers  appears to exert a critical influence on PV in the regulation of feeding behavior  of PV stimulates feeding behavior  system for activation-induced feeding, and an inhibitory ZI and LHy system that suppresses feeding. As PVa and PVp projections differ (see above), this dichotomy in PV's role in feeding could be attributed to the differential involvement of the PVa and PVp in feeding behavior. This was, in fact, proposed by Meffre et al.  stating There is a clear overlap in systems controlling feeding and drug abuse, including PV, which supports the view that addictive drugs act through the natural reward circuitry. A leading advocate of this position, Martin-Fardon and Boutrel  stated: Attention has only recently focused on the role of PV in drug abuse. In early reports, Deutch and colleagues , ORX serves an equally important role in drug-related behaviors—including ORX actions on PV  ORX cells of the LHy fire at high rates during active wakefulness, and at significantly reduced rates during drowsy or sleep states; (2) ORX agents/agonists produce prolonged periods of wakefulness, while ORX antagonists significantly increased amounts of NREM and REM sleep; (3) ORX mutant (KO) mice cannot maintain long periods of wakefulness and repeatedly vacillate between sleep/wake states; (4) ORX cells are reciprocally connected to all “arousal-related” nuclei of the brain; and (5) deficits in ORX signaling produces narcolepsy in rodents, dogs and humans  nuclei of the thalamus were initially thought to project widely throughout the cortex and exert rather undifferentiated effects on behavior, it has recently been shown that each of the midline/ILt nuclei exhibit a unique pattern of projections and participate in distinct functions. In this regard, the differences between RE and PV projections and functions are striking. While RE and PV share common inputs, projections to RE are more widespread and diverse, especially from the brainstem and hypothalamus. With respect to output, there are major differences in RE and PV projections. Specifically, RE almost solely targets limbic cortical structures, such as the orbitomedial, insular, retrosplenial, and parahippocampal cortices and the HF, and minimally subcortical sites, mainly projecting to the rostral ACC. By contrast, PV predominantly distributes to limbic subcortical sites, including the septum, BST, olfactory tubercle, ACC, amygdala, and hypothalamus—with cortical projections essentially limited to the ventral mPFC (IL and PL) and ventral subiculum.The functional properties of RE and PV parallel their respective projections to limbic cortical and subcortical sites; that is, RE is primarily involved in cognitive functions and PV in motivated behaviors. As reviewed, RE has been shown to serve a critical role in various cognitive functions to include working memory/SWM, executive functions  and contexual fear memory. The role of RE in cognitive functions appears largely dependent on RE's position as a key interface between the HF and the mPFC (and ORB)—in the two-way exchange of information between these structures. As described, RE-mediated disruptions of communication between the hippocampus and the mPFC or ORB produces deficits in SWM, executive functions, and contextual fear memory.By contrast, PV has been shown to serve a crucial role in motivated behaviors. We focused on PV's involvement in appetitive functions: feeding, drug addiction and arousal. The PV has been shown to be an integral part of hypothalamic-thalamo-ventral striatal circuit subserving appetitive behaviors. With respect to feeding, both the activation and suppression of PV induces feeding, putatively through discrete actions on PVp and PVa, respectively, controlling different aspects of feeding. With respect to drug addiction and arousal, ORX input from the hypothalamus to PV has been shown to exert a potent influence on PV in these behaviors. Various manipulations that alter ORX actions on the PV suppress drug seeking behavior and reinstatement, and dampen arousal responses in PV.While the dorsal (PV) and ventral (RE) midline thalamus largely serve separate roles in cognitive and motivational behaviors, PV and RE also commonly participate in certain functions, notably, in affect/fear and arousal. For instance, RE is recruited in unlearned fear and anxiety, in addition to conditioned learned fear, whereas PV, as reviewed, participates in various appetitive/aversive behaviors but also has recently been linked to innate and learned fears, as well as anxiety  of thalamus encompass a collection of nuclei located in the medial and dorsal part of the thalamic complex. The intralaminar thalamic nuclei are located lateral to the mediodorsal nucleus and “embedded” within the internal medullary lamina. As previously indicated, the intralaminar nuclei are divided into a rostral and caudal division, with the rostral group consisting of the central medial (CM), paracentral (PC), and central lateral (CL) nuclei. We discuss the circuitry and function of the rostral intralaminar nuclei, with an emphasis on CM, as its connections more closely parallel those of the midline thalamic nuclei than do other ILt nuclei.The main sources of afferents to the rostral ILt arise from structures/regions of the brainstem and cortex. The following brainstem nuclei project to the rostral ILt: dorsal and median raphe nuclei Vertes, , locus cRegarding cortical afferents, the PFC is a prominent source of projections to the rostral intralaminar nuclei, with differences in afferents to CM, CL, and PC  cortex and CL the adjacent secondary motor cortex (AGm). More specifically, PC primarily distributes to the dorsal and ventral AC, and secondarily to AGm and caudally to the retrosplenial (RS) cortex—with minimal projections to other cortical regions. CL mainly targets AGm, with additional projections to the primary motor cortex (AGl), primary and secondary somatosensory cortices, the retrosplenial cortex, and the occipital cortex . PC and CL distribute to the dorsomedial and dorsolateral striatum, respectively, and hence as a pair, encompass the entire dorsal half of the striatum. The PC and CL innervate medium spiny neurons (MSNs) of the dorsal striatum , responsible for states of arousal/consciousness  to processes of arousal and consciousness . Baker et al.  describee et al.  similarlBlumenfeld and colleagues  and midline nuclei of thalamus serve well-recognized roles in cognitive functions, the ILt nuclei also participate in higher order cognitive processes  interneurons of the C-P  and ventral (RE) midline thalamus are strikingly different. In like manner, the anatomical and functional characteristics of ILt significantly differ from those of RE/PV. However, the functions of these thalamic nuclei complement one another, signifying an integrated role for the midline/ILt thalamus in limbic-associated functions. The midline and ILt nuclei receive a diverse array of input from the brainstem including aminergic and ACh nuclei, but the rostral ILt, distinct from PV/RE, receives prominent projections from the pontomesencephalic RF. In further contrast with RE/PV, the ILt receives only modest projections from the hypothalamus. Additionally, there are marked difference in cortical afferents to the midline and ILt thalamus. The sensorimotor cortex distributes densely to CL, while mainly avoiding midline structures. By comparison, the mPFC strongly targets the midline and intralaminar thalamus, with projections differing from the dorsal and ventral mPFC. For instance, the ventral mPFC  projects strongly to RE and PV, moderately to CM, and essentially avoids CL . By contWith respect to output, t1he main targets of CL/PC are sensorimotor cortices and the dorsal striatum. CM also distributes heavily to these sites, but additionally to parts of the limbic cortex, to the ACC and to the amygdala, mainly to BLA. Unlike, however, PV and RE which are reciprocally linked with the HF/subiculum, there are no CM connections with the HF. In addition, in contrast to the absence of PV/RE projections to C-P, CM distributes massively throughout the dorsal striatum and modestly to ACC. Interestingly, CM lies along the midline, and as such shares projections with the dorsal and ventral midline thalamus; that is, limbic subcortical projections with PV and limbic cortical ones with RE. Accordingly, CM appears to serves as an anatomical and functional bridge to the dorsal and ventral midline thalamus.Whereas, both RE and ILt subserve cognitive processes, their roles in cognition differ, undoubtedly owing to their differential projections: RE to limbic cortices and ILt/CL mainly to sensorimotor cortices and the dorsal striatum. Specifically, lesions/inactivation of the ILt produce impairments on cognitive tasks that involve sensorimotor components such as visuospatial, reaction time, instrumental, or sensory discrimination tasks, but essentially unlike RE, do not alter behavior on spatial working memory tasks.The midline and intralaminar nuclei of the thalamus have traditionally been characterized as a single or unified system with common projections and functions. As reviewed herein, there are not only marked anatomical and functional differences between the dorsal and ventral midline thalamus but also between the midline thalamus and the rostral intralaminar complex of the thalamus. While each of the midline and intralaminar nuclei perform distinct functions, they collectively serve a critical role in several affective, cognitive and executive behaviors—as major components of a limbic brainstem/diencephalic-thalamic-cortical circuitry .The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.RV, SL, and AR contributed to writing. SL created the figures. All authors were involved in the preparation of the manuscript. All authors contributed to the article and approved the submitted version.This was supported by NIH grants: NS108259 and NS119847.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Schwann cells (SCs) dominate the regenerative behaviors after peripheral nerve injury by supporting axonal regrowth and remyelination. Previous reports also demonstrated that the existence of SCs is beneficial for nerve regeneration after traumatic injuries in central nervous system. Therefore, the transplantation of SCs/SC-like cells serves as a feasible cell therapy to reconstruct the microenvironment and promote nerve functional recovery for both peripheral and central nerve injury repair. However, direct cell transplantation often leads to low efficacy, due to injection induced cell damage and rapid loss in the circulatory system. In recent years, biomaterials have received great attention as functional carriers for effective cell transplantation. To better mimic the extracellular matrix (ECM), many biodegradable materials have been engineered with compositional and/or topological cues to maintain the biological properties of the SCs/SCs-like cells. In addition, ECM components or factors secreted by SCs also actively contribute to nerve regeneration. Such cell-free transplantation approaches may provide great promise in clinical translation. In this review, we first present the current bio-scaffolds engineered for SC transplantation and their achievement in animal models and clinical applications. To this end, we focus on the physical and biological properties of different biomaterials and highlight how these properties affect the biological behaviors of the SCs/SC-like cells. Second, the SC-derived biomaterials are also reviewed and discussed. Finally, the relationship between SCs and functional biomaterials is summarized, and the trends of their future development are predicted toward clinical applications. Central nervous system (CNS) and peripheral nervous system (PNS) constitute the large neural network in the human body. The CNS, which includes brain and spinal cord, communicates with other organs/tissues through the PNS, perceives and processes information from external environment and maintains the biological functions of living bodies. Neurons and glial cells are the main cell types in the nervous systems. Neurons can receive internal and external stimuli, conduct nerve impulses, and integrate information. Most neurons have multiple dendrites and one axon. The axon conducts nerve impulses from the soma to the downstream neuron or effectors (such as myocytes). Meanwhile the dendrites receive information and transmit it to the soma. Glial cells, such as Schwann cells (SCs) in the PNS and oligodendrocytes in the CNS, wrap around axons and form insulating myelin structures, which facilitate rapid conduction of electrical impulses and protect neurons. Specific injuries in the nervous system  may disturb the interactions between neurons and glial cells, even result in complete impairment of the motor/sensory activities of the whole body.Peripheral nerve injury (PNI), which is usually caused by mechanical trauma  and disease complications , often results in long-term numbness, loss of motor/sensory function, neuropathic pain, or paralysis  , often serve as the alternatives to autologous nerve grafts. Many FDA approved biocompatible and biodegradable polymers are used for NGCs fabrication, such as poly (L-lactic acid) (PLLA), poly (ε-caprolactone) (PCL), silk fibroin, alginate, and the extracellular matrix (ECM) derived materials, including collagen, hyaluronic acid, and fibrin  is also significantly different from PNI. The CNS is made up of gray matter and white matter, the gray matter mainly consists of neuronal somas, dendrites, and glial cells , and the white matter mainly consists of axons and glial cells , as well as some ECM proteins, such as laminin and fibronectin, which can stimulate the intrinsic capability of the damaged neurons to survive and facilitate axonal extension , and N-cadherin are secreted by SCs to promote neuron survival and axonal elongation  is up-regulated in long-distance nerve injury and key regulators of the repair phenotype  is delayed, resulting in diminishing repairing effect  derived/differentiated from stem cells provide a great promise as the SCs substitution for nerve injury repair , produced by substituting amines in gelatin with methacrylamide, can form photocrosslinkable hydrogel with additional photoinitiator. Due to the rapid gelation and stable mechanical properties, GelMA has been broadly used for 3D bioprinting and cell encapsulation  peptide. Gelatin possesses good biocompatibility, degradability, and low immunogenicity, which supports cell infiltration, adhesion, and proliferation  tumor cell lines by proteolytic digestion  based hydrogels are one of the most frequently used carriers for cell delivery due to its non-toxicity, biocompatibility, low protein adsorption, and non-inflammatory invasion  (PHEMA) and poly[N-(2-hydroxypropyl)-methacrylamide] (PHPMA)  (PLA), polycaprolactone (PCL), and poly-3-hydroxybutyrate (PHB) play an important role in scaffold preparation for SC transplantation. Bio-scaffolds can be fabricated with different architectures, such as the aligned fibers and microchannels, to regulate cellular behaviors, sometimes more suitable for the treatments of nerve defects. The limitation of biomaterial scaffolds is that the transplanted SCs often grow only on the surface of the scaffolds, which is quite different from the 3D hydrogels.Many scaffolds that have been used for transplanting SCs and SCLCs were simply fabricated with isotropic architectures, such as nanofibrous or interconnected porous structures. These scaffolds are either fabricated by solvent evaporation from hydrogels or polymer solutions using lyophilization or vacuum drying. Polymer solutions can be dispersed in a defined mold, then dehydrated into a tubular shape. The medium suspensions of SCs and SCLCs are infused into the lumen of the dry tube, and the tube can absorb the medium and distend to form a hydrogel-like or hydrated scaffold. For example, a gelatin hydrogel tube was first made by dehydration, followed by injection of SCs or ADSCs suspension. After incubation in the medium, the hydrated gelatin tube was implanted into a 5 mm-sciatic nerve lesion. The results confirmed that SCs were retained in the gelatin tube after 8 weeks  is a unique approach to introduce longitudinally oriented microchannel structures inside the scaffold  neurites were proven to grow along the SCs  and heat shock proteins  are involved, different cell phenotypes secrete different exosomes that carry various types of biological substances  within 8 weeks  that manipulate SCs phenotype are also valuable for SCs transplantation.Although great advancements have been achieved in clinical applications, the cell-based therapy still faces serious limitations, such as the quantity of cells, timing of the treatment, high costs, and potential immune response. Therefore, alternative approaches using the secreta of SCs or SCLCs, such as their secreted exosomes and ECM have been actively developed and shown great promise in facilitating nerve regeneration. However, due to the complexity of exosomes and dECM, the specific roles of each component and the mechanisms on neural regeneration are barely investigated. Future studies focusing on understanding the role of SCs-derived exosomes and dECM can help evaluate the safety and effectiveness of these rapidly advancing biomaterials toward practical use in future clinical applications.YB and DQ provided the idea for the review. ZR searched the literature, prepared the figures, and wrote the manuscript. ZL and PS participated in reviewing the literature. YB contributed to editing and approval of the final manuscript. All authors contributed to the article and approved the submitted version.This work was supported by National Natural Science Foundation of China , the Key Areas Research and Development Program of Guangdong (2020B1111150003), Natural Science Foundation of Guangdong (2022A1515011388), Science and Technology Program of Guangzhou (201904010364), and Science and Technology Projects in Guangzhou (202002020078).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Livestock and poultry germplasm resources are national strategic resources related to the global revitalization of the seed industry. As an important part of livestock, velvet deer germplasm resources must be taken seriously. Our review focuses on the situation and utilization of velvet deer germplasm resources in China. We mainly introduce the situation of velvet deer germplasm resources in China, such as ecological distribution and the number of subspecies. We further elaborate on the domestication and breeding development of velvet deer in China and put forward suggestions on the scientific utilization of velvet deer germplasm resources.Velvet deer are not only a representative special economic animal but also an important part of livestock. With the increasing awareness of international competition for germplasm resources in China, more and more attention has been paid to the protection and utilization of germplasm resources. However, there is poor understanding about velvet deer resources. Therefore, we are providing a comprehensive introduction of Chinese velvet deer germplasm resources from the aspects of ecological distribution, domestication and breeding. There are abundant deer resources in China, among which sika deer and red deer, the main velvet deer, have important economic value. Nowadays, due to the imbalance between supply and demand, international competition and other aspects, the velvet deer industry is developing slowly and the output value decreases yearly. Most importantly, weak awareness of velvet deer germplasm resource protection is also a direct cause of the slow development of the velvet deer industry that is resulting in its gradual loss of competitiveness. This is a reminder that scientific protection and rational utilization of velvet deer germplasm resources are the key to promoting the stable development of the velvet deer industry. In this paper, the present situation of velvet deer germplasm resources in China is introduced, the development of velvet deer germplasm resource utilization is expounded, and the scientific utilization of velvet deer germplasm resources is put forward, with the aim of providing the theoretical basis for velvet deer and other livestock germplasm resources protection and breeding innovation.China is rich in deer resources, with 21 species, which accounts for 41.7% of deer species in the world [Cervus nippon taiouanus, Cervus nippon hortulorum, Cervus nippon grassianus, Cervus nippon kopschi, Cervus nippon mandrinus and Cervus nippon sinchuanicus [Cervus nippon hortulorum, Cervus nippon kopshi, Cervus nippon taiouanus and Cervus nippon sinchuanicus [Cervus nippon hortulorum are distributed in Heilongjiang and Jilin provinces. Because of excessive domestication, wild individuals were once considered extinct. Later, a small number were found in the border areas of southeast Heilongjiang province and eastern Jilin province [Cervus nippon kopshi are mainly distributed in Anhui, Zhejiang and Jiangxi provinces [Cervus nippon taiouanus was recovered from extinction through artificial rearing. The number of wild individuals was about 1000 by 2013, and they mainly lived in Taiwan [Cervus nippon sinchuanicus are mainly distributed in Sichuan Tiebu Sike Deer Nature Reserve, and the number reached about 800 in 1999 , seven bred varieties  and a bred strain (Changbai mountain sika deer) have been bred.Velvet deer have been domesticated in China for hundreds of years. At present, domestic sika deer in China are mainly domesticated from Concerning the number of domestic sika deer, the available national census data show that by the end of 2004, there were 9465 farms in China and the total stock of sika deer was 452,355, of which, Jilin Province accounted for more than half of the national total stock . In receCervus elaphus songaricus, Cervus elaphus yarkandensis and Cervus elaphus xanthopygus. Cervus elaphus yarkandensis have been cultivated on a large scale in Xinjiang, and the bred variety is called Tahe red deer. By April 2006, there were about 70,000 domestic red deer in Xinjiang [Red deer are a kind of large-scale deer and have high production performance. The mainly domestic red deer are Xinjiang . Among tXinjiang  and 54,0Xinjiang . In addiXinjiang , and theXinjiang .Germplasm resources, also known as genetic resources, generally refer to various biological types for specific germplasm or genes that can be used for breeding and other research. In addition to the wild and domestic living germplasm resources, the institute of Special Animal and Plant Science of the Chinese Academy of Agricultural Sciences has also established a comprehensive velvet deer germplasm resource pool, which contains a total of 4500 sika deer living resources, 7331 frozen semen samples, 150 tissue samples, 180 somatic cell samples and nearly 39,000 blood and DNA samples. In addition, more than 10,000 gene sequences  have been preserved, and the chromosome-level genome of the sika deer has been assembled. Further, about 18,000 red deer blood samples and about 30,000 frozen semen samples have been collected. The velvet deer germplasm resource bank will provide sufficient material for the innovation of velvet deer germplasm resources.Germplasm resources are the material basis of modern breeding. Different types of germplasm resources have different genetic characteristics. An in-depth study of velvet deer germplasm resources will not only help to clarify the origin, evolution, classification and other issues, but it will also lay a great foundation for breeding innovation.As a basic breeding method, pure breeding plays a role in maintaining and improving the good quality of varieties. It has been widely used in the breeding of pigs , sheep , cattle Nowadays, antler velvet is a major source of income for the Chinese velvet deer industry. Therefore, velvet antler production performance has become the main goal of velvet deer breeding. As an important breeding method, hybridization is widely used in the modern livestock breeding industry and aims to breed new varieties with high production performance and improve the production efficiency of livestock, thereby achieving improved industrial gains. In order to improve the velvet antler-producing performance of velvet deer, China has carried out more than 70 years of cross-breeding with nearly 30 kinds of cross combinations, including hybridizations between red deer subspecies, sika deer varieties and interspecies hybridizations of sika deer and red deer .Because of reproductive isolation, the offspring of most interspecific hybrids are not as adaptable as their parents. They are sterile or even lethal . HoweverWith the development of biotechnology, the breeding of velvet deer has gradually developed to the molecular level. More and more molecular methods have been used to develop the utilization of velvet deer germplasm resources. The premise of the breeding innovation of velvet deer is to ensure the purity of the germplasm resources. The 1K chip, developed based on resequencing technology, can accurately distinguish sika deer, red deer and hybrids and judge the degree of hybridization . SimilarMolecular breeding of velvet deer is mainly based on molecular markers. Previous studies have found that ANXA2 , TRPC6 , HMG20A OAS2 and ALYREF/THOC4 [OAS2 and ALYREF/THOC4 may be related to the weight of velvet antlers [Genomic selection (GS) is a molecular breeding technology that uses the whole genome’s genetic markers of reference groups with genotypes and phenotypes to build models and predict the phenotypic value of genotype-only individuals . It has EF/THOC4 , and it  antlers . As a me antlers . HoweverNational Standards for Chinese Sika Deer and the National Standards for Northeast Red Deer. The purity of velvet deer should be detected by genome-sequencing technology. A genetic resource databank of velvet deer should be established. Velvet deer which have been identified for breeding should be registered, which would provide the basis for the follow-up work on germplasm resource protection and breeding innovation.The germplasm resources of velvet deer have rich diversity in phenotypes and genetic background. Therefore, multi-dimensional identification and evaluation should be conducted when identifying the germplasm resources of velvet deer. The appearance and the production performance of velvet deer should be evaluated according to the Breeding innovation with a stable genetic basis must be based on pure-breds. Cross breeding is an effective way of breeding innovation. Therefore, it is important to keep the balance between pure-bred resource protection and the development of breeding innovation. It is necessary to establish a sound system to protect the velvet deer germplasm resources as well as to make innovation in cross breeding to the greatest extent. The national sika deer conservation farm has been established to protect the local variety of sika deer in Jilin Province. The cooperation between research institutions and enterprises that rear sika deer has been established to lay a foundation for genetic improvement and breeding innovation of sika deer. The gene pool of velvet deer has also been created, which contains the genome, transcriptome and proteome data of velvet deer. It is a huge investment to construct national conservation farms. Therefore, national conservation farms can be built by relying on the large and medium-sized rearing enterprises of velvet deer, which cannot only reduce the cost of conservation farm construction but also maximize the use of velvet deer germplasm resources and improve the awareness of enterprises on the protection of velvet deer germplasm resources. In addition, the genetic resources of velvet deer should also be paid attention to. With the help of biotechnology, the characteristics of velvet deer genetic resources should be evaluated and the genes related to production performance can be identified to promote the development and utilization of velvet deer germplasm resources.There have been nearly 75 years of cross-breeding of velvet deer in China. However, because of the lack of systematic and scientific selection, a new variety with excellent production performance and stable inheritance has not been obtained. It is urgent to speed up the process of velvet deer breeding innovation. The innovation of velvet deer germplasm resources requires more breeding of new varieties in addition to genetic improvement of existing velvet deer varieties. With the rapid development of biotechnology, molecular methods for breeding have been used on more and more livestock. Breeding based on species genome will be an inevitable choice for future breeding innovation. Therefore, a genomic selection system and high-density SNP breeding chips for different breeding needs should be developed to complete an efficient and scientific genome-based breeding system of velvet deer.As a national strategic resource, livestock and poultry germplasm resources in China are facing fierce international competition. Velvet deer, as a special part of livestock, also face the same problem. In order to effectively solve the problem, an identification and evaluation system of velvet deer germplasm resources must be completed, a protection system of velvet deer germplasm resources must be established, and an innovation process of velvet deer germplasm resources must be accelerated so that the level of protection and utilization of velvet deer germplasm resources can be comprehensively improved in China.


Ovarian cancer (OC) is a highly lethal neoplasm with a poor rate of response to current treatment. A prerequisite to designing and validating innovative and more efficacious therapies is a deeper understanding of the biological mechanisms that underlie OC progression and chemoresistance. Such an objective, in turn, requires experimental models that mimic the disease as faithfully as possible. In this context, great help comes from the use of patient-derived material, which is key to establishing clinically relevant models. This review summarizes the different categories of in vitro patient-derived OC models and outlines their ability to represent specific aspects of OC biology and provide new tools for personalizing the treatment of such a devastating disease.Epithelial ovarian cancer (OC) is the most lethal gynecological malignancy worldwide due to a late diagnosis caused by the lack of specific symptoms and rapid dissemination into the peritoneal cavity. The standard of care for OC treatment is surgical cytoreduction followed by platinum-based chemotherapy. While a response to this frontline treatment is common, most patients undergo relapse within 2 years and frequently develop a chemoresistant disease that has become unresponsive to standard treatments. Moreover, also due to the lack of actionable mutations, very few alternative therapeutic strategies have been designed as yet for the treatment of recurrent OC. This dismal clinical perspective raises the need for pre-clinical models that faithfully recapitulate the original disease and therefore offer suitable tools to design novel therapeutic approaches. In this regard, patient-derived models are endowed with high translational relevance, as they can better capture specific aspects of OC such as (i) the high inter- and intra-tumor heterogeneity, (ii) the role of cancer stem cells , and (iii) the involvement of the tumor microenvironment, which interacts with tumor cells and modulates their behavior. This review describes the different in vitro patient-derived models that have been developed in recent years in the field of OC research, focusing on their ability to recapitulate specific features of this disease. We also discuss the possibilities of leveraging such models as personalized platforms to design new therapeutic approaches and guide clinical decisions. Ovarian cancer (OC) is the seventh most common cancer affecting women and the deadliest gynecological malignancy worldwide . Due to HGSOC is the most frequent type of OC (70%) with a survival rate of only 30% at 5 years . The staVery few alternative therapeutic strategies have been designed so far for the treatment of recurrent HGSOC, mainly due to the lack of common mutations that could become actionable targets. In fact, apart from TP53 mutations, which are present in almost 95% of cases, no shared genomic alterations have been identified in HGSOC patients until recently . Only inThe development of recurrent chemoresistant disease is not the only reason for the poor clinical outcome of HGSOC patients. Another reason is the transcoelomic dissemination and spreading of the disease in the peritoneal cavity. Indeed, tumor cells shed from the primary tumors and are able to reach the peritoneum and the omentum (which are the main sites of HGSOC metastatization) and all the organs of the abdominal cavity carried by the peritoneal fluid, or by ascites, which is frequently present in advanced-stage OC patients . The main players in the processes of metastatization and recurrence are ovarian cancer stem cells . By definition, OCSCs have the ability to self-renew and initiate tumorigenesis; moreover, they are intrinsically resistant to cytotoxic treatments, thereby they survive standard chemotherapy, and are responsible for tumor re-growth and relapse .Given this complex scenario, there is an urgent need for preclinical models able to capture and faithfully reproduce all the aspects of EOC and amenable to be used for efficient drug discovery. Since most of the traditional immortalized cancer cell lines have proven unable to recapitulate the behavior of such a heterogenous disease , there iIn OC, primary cell cultures can be established from malignant ascites or from the mechanical/enzymatic dissociation of solid tumors. Tumor cells can be cultured in 2D adherent conditions as primary short-term cultures or immortalized to generate cell lines with unlimited replicative potential. The immortalization of OC cell lines is often time-consuming and presents a low success rate. Indeed, 10 years of various attempts and optimization were needed by Ince and colleagues to define the proper culture conditions that allowed them to generate (and make available to researchers) a panel of 25 immortalized OC cell lines, derived from primary tumors with different histology . These cOn the other hand, the establishment of primary cultures from OC specimens has a high success rate of up to 90% ,17. In aPrimary cell cultures can also be employed for in vitro functional assays of clinical relevance, such as the assessment of HR status by measuring RAD51 foci formation as part of the DNA damage response . Anotheranoikis, self-renew, and proliferate when seeded at a low density in non-adherent conditions with a serum-free medium . Such stringent culture conditions allow for the enrichment of primary tumor cultures for cells endowed with stem-like features. Indeed, it has been demonstrated that cells derived from spheroids express high levels of stem genes and exhibit high tumor-initiation ability [Once primary OC cell cultures have been established, it is possible to generate 3D spheroid cultures from them, exploiting fundamental properties of OCSCs, namely their ability to resist  ability ,26. In t ability .In this regard, patient-derived 3D spheroids have been shown to be more resistant to platinum than their adherent counterpart , and theFor example, Lupia et al. profiled the transcriptome of patient-derived OCSCs and identified CD73 as a marker and a driver of stemness in HGSOC . InteresTwo studies have been recently published with a thorough comparison of transcriptional and genomic profiles of matched primary ascites, 2D and 3D spheroids cultures ,29. The work by Lupia and colleagues  showed hA similar approach was followed by Velletri and colleagues , who anaIn general, the superiority of 3D vs. 2D cultures in reproducing the physiological cell–cell and cell–matrix interactions is now well established, as is the improved ability of 3D models to mirror the response to therapies of real tumors . In thisMoreover, given the high heterogeneity of OC and the lack of innovative therapeutic strategies, PDOs have attracted huge interest as platforms to perform drug screenings in a personalized way, and several recent studies have made efforts in the optimization of culture conditions and methods for viability assessment.For example, Phan and colleagues described a method to generate PDOs by seeding a mix of tumor cells and Matrigel in a ring shape around the rim of the wells of 96-well plates. This geometry allowed one to easily change medium, add drug treatments and measure their effects on organoids number, morphology and viability, rendering this platform amenable for high-throughput drug screenings .Hill and colleagues established a platform of short-term patient-derived HGSOC organoids to evaluate the correlation between defects in the DNA repair machinery and sensitivity to different drug treatments. They generated 34 organoid lines from 22 patients with HGSOC (and 1 with LGSOC), from both primary and metastatic lesions. Tumor tissue was digested into small multicellular aggregates that were embedded in Matrigel and grown in media supplemented with various growth factors . All assays were conducted on short-term organoid cultures . In this time frame, organoids maintained the histological organization, as well as most of the somatic mutations, copy number alterations, and other genomic features of the original tumors. The authors then conducted a thorough analysis of DNA repair defects in their organoid platform, using different approaches. In particular, they tried to correlate the results from genomic analyses  with functional properties  and sensitivity to a panel of compounds, comprising (i) drugs targeting defects in DNA repair machinery, such as the PARP inhibitor olaparib; (ii) drugs inducing replication fork stalling such as carboplatin, prexasertib (CHK1 inhibitor) and the ATR inhibitor VE-822; (iii) drugs inducing replication stress, such as gemcitabine. Indeed, the authors showed that functional assays were more effective than genomic analysis in predicting the response to different drugs. In fact, irrespective of BRCA1 or 2 mutations, organoids unable to form RAD51 foci were sensitive to PARP inhibition, while organoids positive for RAD51 foci were resistant to olaparib treatment but sensitive to carboplatin, prexasertib, VE-822, and gemcitabine. Notably, the effect of these drugs on the organoids matched the response of the patient of origin. Moreover, the authors demonstrated that sensitivity to carboplatin, prexasertib, VE-822, and gemcitabine was associated with replication fork instability, while carboplatin resistance correlated with fork stability [The first report of this achievement came from Kopper et al., who established 56 organoid lines from 32 patients with different histological types of OC, both pre- and post-chemotherapy treatment. Original tumors were dissociated, and tumor cells were embedded in BME (basement membrane extract) instead of Matrigel. Interestingly, some of the organoids required the presence of Wnt in the culture media, while others did not. The authors showed that organoids maintained histological organization and biomarkers expression of the original tumors, as well as genomic features, even after several passages, and they also recapitulated the general genomic landscape of OC in terms of Copy Number Variations (CNV) and common mutations. The organoid platform was then used to assess the sensitivity to a wide panel of drugs, ranging from carboplatin and paclitaxel (commonly used in the clinic) to gemcitabine, inhibitors of the PI3K/AKT/mTOR pathway, PARP inhibitors, and Wee1 inhibitors. Similar to what happens in patients, most HGSOC organoids were sensitive to carboplatin, while organoids from other subtypes were less sensitive. Interestingly, for one patient, the authors derived organoids from the primary chemosensitive tumor and from the recurrent chemoresistant lesion, and the latter showed decreased sensitivity to carboplatin in vitro, thus mirroring the behavior of the original disease .Two more studies have been recently published describing other PDO platforms, which differed from the work by Kopper et al. due to the composition of the culture medium, the protocol for Matrigel embedding , and the overall efficiency in the derivation of stable cultures. Importantly, all these PDOs recapitulated both histological and genetic characteristics of the original tumors, did not accumulate significant mutations during long-term culture, and were also able to capture intra-tumor heterogeneity ,37.The organoid platforms described so far were generated from heterogenous clinical specimens, comprising primary tumors, metastatic lesions from different anatomical districts, and tumors of different types and stages, either chemo-naïve or treated with chemotherapy. Instead, Hoffmann and colleagues generated 15 stable organoid lines from 13 advanced HGSOC patients prior to chemotherapeutic treatments, using samples derived only from peritoneal and omental primary lesions. In this work, they expanded the findings of Kopper et al. that some organoids did not grow in the presence of activated Wnt signaling and clearly demonstrated that the activation of the Wnt pathway in HGSOC organoids strongly decreased the growth ability and percentage of stem cells, down-regulated the expression of stemness genes, and up-regulated genes linked to differentiation, shedding light on pivotal mechanisms required for stem cell maintenance in OC .In some of the above-mentioned studies, the responses of organoids to drugs was compared with that of the original patients, but only for a small number of cases. De Witte et al. investigated the correlation between in vitro and clinical sensitivity in a more systematic manner. Indeed, they selected seven PDOs derived from interval debulking surgery of HGSOC patients, challenged them with carboplatin and paclitaxel and showed a significant correlation between the sensitivity of PDOs and clinical response of matched patients  . SimilarDe Witte and colleagues also showed that it was possible to assess the response of PDOs to a broader spectrum of drugs (from 3 to 17 per PDO) in a maximum timeframe of 3 weeks, which could be compatible with clinical practice  . OverallThe predictive value of PDOs has been emphasized in many of the above-mentioned studies, and they are commonly perceived as a better system than classical 2D cultures in this regard. However, to our knowledge, a systematic comparison between patient-matched organoids and 2D cells for their ability to mimic the treatment response of the original tumor has not been performed. Thus, the jury is still out for a formal confirmation that PDOs are preferable to conventional cell cultures when attempting to anticipate a patient’s response to therapies.All the patient-derived models described so far—primary 2D adherent cultures, 3D floating spheroids, and 3D organoids—share a major drawback, namely, the absence of the tumor microenvironment (TME), which actually plays a major role in OC progression. Indeed, it is now clear that continuous bi-directional communication takes place between OC cells and their microenvironment: the tumor recruits stromal cells and shapes the TME, which, in turn, sustains the growth, spread, and stemness of cancer cells . This crTo this end, in vitro 3D organotypic models of ovarian TME have evolved through the years to include almost all the stromal components of the major metastatic site for OC, the omentum. The latter is a large fold of the peritoneum covering the intestine, composed of a monolayer of mesothelial cells covering a sub-mesothelial region that contains an extracellular matrix, blood and lymph vessels, fibroblasts, adypocites, and immune cells . The useAn added value of these organotypic models is that they can be easily adapted for quantitative high-throughput pharmacological screenings, aimed at identifying compounds that specifically target the ability of OC cells to adhere, invade, or proliferate on the omental TME, without affecting the stromal component, hopefully leading to a durable clinical response ,49,50.The omental organotypic models described so far presented two major limitations: first, most of the studies performed previously have exploited OC cell lines for the tumor compartment, thus decreasing the clinical and translational relevance of their findings; second, not all the components of the omental TME  were included in the co-cultures, precluding the possibility to fully address tumor–host interactions that could be relevant for tumor progression. Two recently published studies from Frances Balkwill’s group overcame—at least in part—these issues and described a modular model of omental metastasis in which different cell types can be added, enabling them to investigate their specific functional contribution ,52. AdipThe organotypic models that we have described in the previous paragraph added various cellular populations from the omental microenvironment to the cultures of cancer cells, allowing the study of their reciprocal interactions and to better mimic the organization and the behavior of real tumors. However, not all the stromal components are represented in these models; moreover, the tumor microenvironment is not only composed of diverse cell types but it also entails biomechanical properties that should be considered to generate even more reliable in vitro models. In this context, the stiffness of ECM and the shear stress generated by the presence of ascites have been implicated in various events related to OC progression. In this last paragraph, we will focus on new technologies that could enable the introduction of these variables in patient-derived models, in order to increase their ability to recapitulate all aspects of original tumors.Intriguingly, bioengineered devices can also be exploited to address the question of HGSOC origin. Indeed, Kreeger’s group recently developed a microfluidic device capable of reconstructing the microenvironment (in terms of ECM composition and curvature) of cortical inclusion cysts, which is thought to create a favorable niche for the development of HGSOC ,55. AlthDuring metastasis development, the omentum is dramatically remodeled, both in its cellular components  and in the ECM, leading to an increase in tissue stiffness with disease progression . MoreoveThe presence of ascitic fluid, which often accumulates in the peritoneal cavity of advanced-stage OC patients, exposes tumor cells to several mechanical stimuli, such as shear stress, the functional impact of which can be modeled by means of microfluidic devices. Rizvi and colleagues designed a simple microfluidic chip in which cancer cells, carried by the flow, were allowed to adhere to a Matrigel bed and spontaneously formed spheroids. They then demonstrated that the presence of continuous flow for 7 days induced EMT and the acquisition of an aggressive phenotype in tumor spheroids . A similMicrofluidic devices can be further optimized by adding different compartments and re-creating the tissue–tissue interface, which is the basic principle of organ-on-chip technology . The “OvNotably, while the studies on microfluidic devices described so far relied on OC cell lines for the tumor compartment, “OvCa-Chips” were also used with primary patient-derived tumor cells . This hiWe have provided an overview of the in vitro models that have been generated so far, starting from patient-derived materials . For eacTumor fragments can also be engrafted in immunodeficient mice and propagated in vivo generating platforms of PDXs, which maintain the histological characteristics of the original tumors . Althou


Nitrogen metabolism is the most basic process of material and energy metabolism in living organisms, and processes involving the uptake and use of different nitrogen sources are usually tightly regulated at the transcriptional and post-transcriptional levels. Bacterial regulatory noncoding RNAs are novel post-transcriptional regulators that repress or activate the expression of target genes through complementarily pairing with target mRNAs; therefore, these noncoding RNAs play an important regulatory role in many physiological processes, such as bacterial substance metabolism and stress response. In recent years, a study found that noncoding RNAs play a vital role in the post-transcriptional regulation of nitrogen metabolism, which is currently a hot topic in the study of bacterial nitrogen metabolism regulation. In this review, we present an overview of recent advances that increase our understanding on the regulatory roles of bacterial noncoding RNAs and describe in detail how noncoding RNAs regulate biological nitrogen fixation and nitrogen metabolic engineering. Furthermore, our goal is to lay a theoretical foundation for better understanding the molecular mechanisms in bacteria that are involved in environmental adaptations and metabolically-engineered genetic modifications. Nitrogen is one of the most dominant nutrients in the environment and is a limiting factor for cell growth. Atmospheric nitrogen is the largest source of freely available nitrogen, but for growth, most organisms rely on the forms of nitrogen that are available . Most microorganisms must convert inorganic nitrogen from the environment into organic nitrogen for their growth requirements through different nitrogen metabolic cycles, such as assimilation, nitrification, denitrification and nitrogen fixation  as well as nitrogen fixation-related genes  through self-phosphorylation or dephosphorylation. Under nitrogen fixation conditions, phosphorylated NtrC transfers low ammonium signals and activates NifA expression, which in turn triggers the expression of all nif genes and results in a complex and elaborate ‘molecular relay’ regulatory mechanism  and biological nitrogen fixation (Nif) in bacteria. It was found that the general nitrogen regulation system, which is involved in nitrogen assimilation and utilization, is widely distributed in bacteria and involves many signal transduction processes and effector proteins, including GlnD, NtrB, NtrC and PII, which are the main proteins. GlnD senses the levels of intracellular glutamine and is the primary receptor for intracellular nitrogen levels, while the PII protein interacts with NtrB to regulate NtrC activity Shimizu . Howeverism Fig. .Recently, many studies on the post-transcriptional regulatory network of bacterial nitrogen metabolism have focused on the identification and functional analysis of noncoding RNAs. Approximately 15 noncoding RNAs have been identified as regulators involved in the regulation of nitrogen metabolism in bacteria, but most of them indirectly regulate nitrogen metabolism; only five noncoding RNAs have been shown to have a direct involvement. It was discovered that all four noncoding RNAs are trans-encoded noncoding RNAs, and their expression is directly controlled by global regulators of nitrogen metabolism; in addition, these RNAs affect the expression of key nitrogen metabolism components  at the post-transcriptional level by inhibiting the initiation of translation or stability of target mRNAs  , γ-proteobacteria , Cyanobacteria and Archaea   and affecting the response of cyanobacteria to abrupt changes in effective nitrogen sources  as scaffolds to design synthetic ncRNAs with specific target gene properties. The two strategies have been successfully used in the production of amino acids, biofuels and other metabolites, such as tyrosine, succinic acid, butanol, propane and N-acetyl glucosamine, in various microbial classes; this indicates that synthetic ncRNA-mediated regulation is effective and controlled in bacterial metabolic regulatory networks , ldhA (which encodes lactate dehydrogenase) and odhA (which encodes the E1 subunit of the 2-oxoglutarate dehydrogenase complex), and successfully inhibited the expression of these three genes, resulting in the enhancement of the extracellular glutamate concentrations by 2.1-fold, 2.8-fold and 1.5-fold, respectively. The yield of glutamate into glucose conversion was also increased from 22.2 mol/mol to 46.7 mmol/mol, 65.0 mmol/mol and 34.5 mol/mol, respectively (Sun et al. Glutamate biosynthesis is critical for nitrogen metabolism systems in bacteria. Glutamate is the main intracellular nitrogen donor, accounting for 88% of intracellular nitrogen, and is also the largest anion pool responsible for maintaining the balance of intracellular Kells Yan . Currentn et al.  publisheEach class of ncRNA that was involved in the control of nitrogen metabolism underwent identification and functional analysis, revealing a new mechanism for the regulation of bacterial nitrogen and demonstrating that ncRNAs play a key role in bacterial gene expression and regulation. However, despite the discovery of several ncRNAs involved in the regulation of nitrogen metabolism, the regulatory network of nitrogen metabolism in bacteria is complex; thus, the current understanding of the regulatory mechanisms of bacterial nitrogen metabolism, particularly at the post-transcriptional and translational levels, is rather superficial, fragmented and one-sided. The biological functions and regulatory mechanisms of ncRNAs involved in the regulation of bacterial nitrogen metabolism are still under investigation.Microorganisms are central organisms in the nitrogen cycle because six of the eight known nitrogen cycles are operated by only microorganisms in nature. However, because of the diversity of microbial metabolism, the regulation of nitrogen metabolism-related gene expression is rigorous and complex. By directly base pairing with target mRNAs, regulatory ncRNAs regulate the expression of target genes at the post-transcriptional or translational level with the help of the RNA chaperone Hfq. In contrast to the traditional focus on the optimization of genetic circuits and metabolic pathways, which occur primarily at the transcriptional level, ncRNAs, as novel regulatory factors, have advantages such as rapid response, flexible and precise control, easy recovery and a lack of metabolic burden. As a result, the development of standardized and intelligent artificial ncRNAs can provide new strategies and tools for the construction of efficient nitrogen metabolic circuits and their widespread application in agriculture.


The use of deep brain stimulation (DBS) for the treatment of chronic pain was one of the first applications of this technique in functional neurosurgery. Established brain targets in the clinic include the periaqueductal (PAG)/periventricular gray matter (PVG) and sensory thalamic nuclei. More recently, the anterior cingulum (ACC) and the ventral striatum/anterior limb of the internal capsule (VS/ALIC) have been investigated for the treatment of emotional components of pain. In the clinic, most studies showed a response in 20%–70% of patients. In various applications of DBS, animal models either provided the rationale for the development of clinical trials or were utilized as a tool to study potential mechanisms of stimulation responses. Despite the complex nature of pain and the fact that animal models cannot reliably reflect the subjective nature of this condition, multiple preparations have emerged over the years. Overall, DBS was shown to produce an antinociceptive effect in rodents when delivered to targets known to induce analgesic effects in humans, suggesting a good predictive validity. Compared to the relatively high number of clinical trials in the field, however, the number of animal studies has been somewhat limited. Additional investigation using modern neuroscience techniques could unravel the mechanisms and neurocircuitry involved in the analgesic effects of DBS and help to optimize this therapy. Chronic pain is a major health problem associated with individual suffering and an important social and economic burden. The prevalence of this condition in the general population ranges from 8% to 50% –3. It isDeep brain stimulation (DBS) involves the delivery of electrical current to the brain parenchyma through implanted electrodes , 7. Its In various applications of DBS, animal models have either provided the rational for clinical use or were utilized to study potential mechanisms of therapeutic responses , 18. DesIn this review, we summarize the effects of DBS in preclinical models and in patients with chronic pain.Prior to discussing preclinical work, it is worth differentiating nociception from pain. The former refers to the neural encoding of impending or actual tissue damage, whereas the later denotes the subjective experience of actual or impending harm. In general, preclinical models are largely suited to measure nociception. That said, animals are likely to have a subjective experience associated with nociception. Unfortunately, measuring this component is not straightforward. To decrease the gap with the human condition, proposed approaches include measures of spontaneous and evoked pain, pain memory, avoidance, anxiety- or depression-like behaviors, and the social modulation of pain (empathy).Structures targeted in preclinical DBS studies are either part of the pain matrix, limbic system, descending analgesic systems, or those potentially capable of modulating nociceptive signals . ItemizeThe PAG is a highly conserved midbrain region that surrounds the cerebral aqueduct . It is aIn an initial report, Reynolds  showed tInitial evidence for targeting the sensory thalamus in pain derived from the ablative neurosurgical literature –31. Sensvia the modulation of raphe-spinal tract fibers  brainstem nuclei involved in the descending pain modulation system , and (ii) limbic structures involved in the emotional valence to painful stimuli, such as the ACC and the amygdala , 62, 64.The limbic system includes a wide range of interconnected brain regions that process and regulate cognitive function, sensory perception, memory, emotions, and affective motivation . VariousThe hypothalamus, a central structure in the hypothalamic-pituitary-adrenal (HPA) axis, is involved in mechanisms of psychiatric disorders, including depression, anxiety, and anorexia. The ventromedial hypothalamus (VMH), in particular, contributes to the processing of the affective dimension of pain , whereasvia the release of oxytocin from descending fibers to the dorsal horn  , 140 andAs described above, optimal DBS targets for the treatment of chronic pain are still under investigation. Possible explanations for the variable results of different preclinical and clinical studies include the complex nature of pain, the study of different conditions leading to the development of pain, and the potential involvement of multiple networks. In recent years, the concept of a traditional pain matrix has been complemented by that of a pain connectome . This isvia the release of oxytocin into the dorsal horn . This question can be potentially addressed in preclinical models using a battery of tests to investigate multiple domains. Also to be examined in preclinical models is the contribution of additional DBS mechanisms for the analgesic effects of this therapy, which go beyond the activation and inhibition of neuronal cell bodies and fibers . These iThe outcome of DBS for the treatment of chronic pain is quite variable. At present, reasons for this variability have been speculated, but not clearly established. In some recently published series and in two multicenter trials, outcome was worse than the one reported in older studies , 177. DeAs some of the effects of PAG/PVG DBS in preclinical models are mediated by endorphins, the clinical use of the morphine-naloxone test has been advocated , 178. DuOne factor that seems to be related to a good postoperative outcome is the clinical condition leading to the development of pain. Patients with brachial plexus avulsion, complex regional pain syndrome, and peripheral neuropathy seem to have a better response to DBS than those with postherpetic neuralgia or thalamic pain , 135. PsAnother factor suggested to forecast a positive response to invasive neuromodulation procedures is the so-called insertional effect, characterized by the amelioration of pain immediately after electrode implantation in the absence of stimulation , 182. ThIn a recent series of studies in patients implanted with both Vc and PVG electrodes, field potentials were recorded in the thalamus during stimulation of the latter , 184. A Despite the complex nature of pain and the fact that animal models do not reflect the subjective nature of this condition, multiple preparations have emerged over the years. These are rooted in dimensions of face, construct and predictive validity , 18, 159