Diacylglycerol kinases (DGKs) play a key role in phosphoinositide signaling by removing diacylglycerol and generating phosphatidic acid. Besides the well-documented role of DGKα and DGKζ as negative regulators of lymphocyte responses, a robust body of literature points to those enzymes, and specifically DGKα, as crucial regulators of leukocyte function. Upon neutrophil stimulation, DGKα activation is necessary for migration and a productive response. The role of DGKα in neutrophils is evidenced by its aberrant behavior in juvenile periodontitis patients, which express an inactive DGKα transcript. Together with in vitro experiments, this suggests that DGKs may represent potential therapeutic targets for disorders where inflammation, and neutrophils in particular, plays a major role. In this paper we focus on obstructive respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD), but also rare genetic diseases such as alpha-1-antitrypsin deficiency. Indeed, the biological role of DGKα is understudied outside the T lymphocyte field. The recent wave of research aiming to develop novel and specific inhibitors as well as KO mice will allow a better understanding of DGK’s role in neutrophilic inflammation. Better knowledge and pharmacologic tools may also allow DGK to move from the laboratory bench to clinical trials. In this review we summarize the rapidly increasing body of knowledge that links diacylglycerol kinases (DGKs) to chronic respiratory diseases. DGKs are lipid kinases that modulate receptor signaling but also contribute to membrane trafficking and shaping. As neutrophils play a key role in chronic respiratory diseases, this article focuses on the numerous, but underappreciated, studies that indicate DGKs, and specifically the α isoform, as key regulators of the neutrophil life cycle.DGKs are intracellular lipid kinases that phosphorylate diacylglycerol (DAG) to phosphatidic acid (PA). In mammals, ten DGK coding genes have been identified and classified into five different subtypes based on the presence of specific regulatory domains . The preIn the C-terminal portion, all isoforms feature a bipartite catalytic domain that identifies this family of enzymes. Unfortunately, this catalytic domain has never been structurally determined. However, it contains an ATP binding site where the mutation of a glycine to an aspartate or alanine renders the DGK kinase dead ,4. In adConversely, a significant divergence between the isoforms instead exists in the N-terminal regulatory domains, allowing to divide them into five classes on the basis of structural homology .N-terminal recoverin homology domain and two calcium-binding EF hand motifs regulating membrane association and activity [Class I—DGKα, DGKβ, and DGKγ are characterized by a conserved activity . Recent activity ,12.Class II—DGKδ, DGKη, and DGKκ are characterized by an N-terminal plekstrin homology (PH) domain mediating the interaction with phosphatidylinositol 4,5-bisphosphate  and, putN-terminal hydrophobic α helix, preceding its tandem C1 domains, which is responsible for endoplasmic reticulum localization [Class III—DGKϵ has an lization . Intereslization . The conlization .Class IV—DGKζ and DGKι contain a myristoyilated alanine-rich protein kinase C substrate domain (MARKS), which regulates protein–protein interactions and enzyme activity in a PKC-dependent manner ,20. ClasClass V—DGKθ contains an N-terminal proline-rich domain, a third cysteine-rich domain, a PH domain, and a putative Ras-association domain within it .The various mammalian DGKs show remarkably specific expression patterns, with most cells expressing multiple DGKs. Often, when several DGKs are expressed in tissues or cells, they are from different subfamilies, suggesting that each subfamily carries out a distinct biological function .The majority of information on DGK’s biological function in neutrophils comes from studies with inhibitors or patients. Indeed, despite the availability of KO mice for DGKα , DGKβ 2, DGKδ 2, DGKε 2, DGKη 2, DGKι 2, and DGKActual knowledge is based on two commercially available DGK inhibitors (named R59949 and R59022), which are widely used in vitro ,32. TheyThe DAG-mediated activation of conventional PKC and RASGRP4 are essential steps in neutrophil signal transduction, which leads to the activation of NADPH oxidase activity, cell movement, and extracellular trap release ,57. ConvDespite the relevance of the lipids metabolized by DGKs, their role in neutrophil differentiation is poorly known. In the HL-60 model cell line, only DGKα, DGKδ, DGKε, DGKγ, and DGKζ were expressed. Notably, DGKα was virtually absent in undifferentiated cells but was strongly upregulated throughout differentiation. Conversely, DGKε, DGKγ, and DGKζ were expressed in undifferentiated HL-60 cells but were strongly downregulated throughout differentiation. The inhibition of DGKα with R59022 and R59949 led to an acceleration of differentiation and concomitant cell cycle arrest . This suwww.immgen.org) indicate that, in mice, DGKα and DGKγ are expressed by bone marrow granulocytes more than in splenic- or thiourea-induced peritoneal neutrophils. Here, DGKδ, DGKθ, and DGKζ are upregulated, while DGKε and DGKη are substantially stable , IgG, opsonized zymosan, LTB4, or IL-8 ,68. Thisore role ,70. Thisore role . The retore role ,73. Paraore role .Multiple genetic defects affecting all stages of neutrophil development, trafficking, transmigration into tissues, and, in some instances, function, have been linked to exceptionally aggressive forms of familial periodontitis, which is a disorder characterized by an exaggerated inflammatory response in the oral mucosa, leading to the destruction of soft tissues and tooth-supporting bone in susceptible individuals .Impaired neutrophil chemotaxis, exaggerated adhesion, and oxidative burst are observed in localized aggressive periodontitis . Interestingly, DAG is elevated in unstimulated peripheral blood neutrophils from LAP patients. These cells also showed an enhanced and prolonged elevation of DAG in response to fMLP or zymosan, due to a decreased metabolism by DGK ,77. Sign2+ influx and the modulation of membrane fusion are required to restore exocytosis in DGKα-inhibited neutrophils, suggesting a perturbation of intracellular vesicular dynamics. This involvement of DGKα-produced PA in membrane trafficking is expected, as DGKs play a pivotal role in intracellular trafficking. DGKα is known to be required for the assembly of multivesicular bodies, the polarized secretion of exosomes by T cells [Anti-neutrophil cytoplasmic antibodies (ANCAs) are autoantibodies (predominantly immunoglobulin G) directed against constituents of neutrophil’s primary granules and lysosomes of monocytes. Among the several ANCA antigenic targets identified until now, the two more clinically relevant and best-characterized are myeloperoxidase and proteinase 3. ANCA antigens are not only secreted by preactivated neutrophils but are also presented on their surfaces, and by binding to them and to the FC receptor, ANCAs inappropriately lead to the activation of primed neutrophils and monocytes . Improve T cells , and als T cells ,87. In a T cells , DGKδ sc T cells , and DGK T cells . The fin T cells .While several studies have addressed the biological role of DGKs, their impact on respiratory disease is not completely enlightened and is still under investigation. Asthma and chronic obstructive pulmonary disease (COPD) are characterized by airflow obstruction and represent the most common non-communicable respiratory diseases with an increasing worldwide prevalence and impact on global health.In relation to asthma, a heterogeneous pattern of inflammatory mechanisms has been identified in the underlying clinical features. The main phenotypes comprise eosinophilic inflammation and Th1 and Th17 neutrophilic inflammation .Eosinophilic inflammation, and consequent type 2 airway inflammation, occurs in a large number of patients, and typically about half of asthmatic patients . The maiAlongside type 2 inflammation, asthma displays other pathophysiologic patterns underlying its clinical manifestation. Actually, non-eosinophilic asthma has been described both in the young and adults . Green eIn relation to eosinophilic inflammation, Wang et al.  conducteDGKα’s role in non-eosinophilic asthma is less clear. The main actors involved in non-eosinophilic asthma are type 1 inflammation cells, including Th1, cytotoxic T-lymphocytes (CTL), and neutrophils. Previous reports have found a reduced transcription of DGKα by IL-2 in CTL ,100. CTLMoreover, Ruffo et al.  showed tThe complex functions of DGKα have also been reported by Shin et al., who found the inhibitory roles of DGKα and DGKζ in the primary anti-viral immune response, while they appear to promote expansion of viral specific memory cytotoxic T cells during secondary infection . The mecSanjuan et al. investigated the role of DGKα in relation to CD69 expression, one of the early markers of T cell activation in relation to TCR stimulation ,106. TheDGK is a physiological modulator of DAG metabolism, limiting PKC activation  but also2+ levels, with a subsequent release of granule proteins and chemotaxis [One of the most powerful stimuli of chemotaxis for neutrophils is represented by CXCL8, produced mainly by macrophages. Neutrophil migration into the respiratory airway represents a crucial step in COPD progression. Neutrophils secrete serine proteases that act by destroying the alveolar matrix and have a consequent impact on airway architecture. CXCL8 binds the neutrophil chemokine receptors CXCR1 and CXCR2. The signaling cascade includes enhancing intracellular Caemotaxis . Moreoveemotaxis .Acute exacerbation in COPD patients is one of the key parameters that assesses the severity and the disability of the disease. During acute exacerbation, an increased percentage of neutrophils in the sputum has been observed. The main explanations involve a higher production of chemotactic factors, including leukotriene B4 (LTB4) and CXCL8 . More spPA has been reported to play a central role in cell adhesion and the migration of leukocytes, especially neutrophils ,116. SpeIn this direction, the study of Xu et al. investigated the α and β isoforms of PKC in neutrophils, which are the main isoforms involved in maintaining polarization and chemotaxis. In resting neutrophils, they are localized in the cytosol, and, after chemoattractant stimulation, they translocate to the membrane through PLC-dependent signaling, suggesting DAG acts as a major determinant in their regulation . PKC plaFew data are available in relation to idiopathic pulmonary fibrosis (IPF). IPF is a chronic, progressive, and fatal disease involving lung interstices . The priPrevious studies have suggested the role of PA produced by PLD in the development of kidney fibrosis , in partRecently, targeting the diacylglycerol metabolism by DGKζ knockdown or treatment with the DGKα-specific inhibitor R59949 has proven to be beneficial for treating asthma by reducing both inflammation and airway hyperresponsiveness . OngoingThe adjustment of DGK activity offers an innovative perspective in the therapeutic manipulation of T cell functions for the treatment of autoimmune pathologies. Having specific information on the mechanisms that sustain DGK isoform-specific regulation in T lymphocytes is crucial for the development of novel tools for pharmacological intervention . While t


The current study investigated psychological stress among parents of competitive British tennis players. Adopting a multipart concurrent mixed method design, 135 British tennis parents completed a cross sectional online questionnaire to examine their primary appraisals, emotions, and coping strategies associated with self-disclosed stressors. Hierarchical content analysis was conducted on open ended questionnaire responses to identify key stressors and coping strategies, and descriptive and inferential statistics were utilized to explore the differences between various components of the process. The findings revealed a range of organizational, competitive, and developmental stressors. These stressors were predominantly appraised as harm or challenge, and anxiety and anger were the most prominent emotions that the parents experienced. Statistically, parents experienced greater anger in relation to competition  stressors, whilst harm appraisal increased negative emotions, and challenge appraisal increased positive emotions. Findings also highlighted how parents used a number of mastery, internal regulation, and goal withdrawal coping strategies, which varied statistically in degrees of reported effectiveness. The contribution of these findings to the stress literature and their applied implications are discussed. Psychological stress among athletes and coaches has been well documented in the sport psychology literature e.g., . TransacAlthough the stress literature has predominantly focused on the experiences of athletes and coaches, researchers have offered initial understanding of the stressors associated with parenting in youth sport . InitiatAlongside this body of work, a small number of studies have explored the emotions that parents experience in youth sport settings e.g., . For exan = 7) of elite youth gymnasts cope with stressors. Their findings suggest that the parents encountered a variety of competitive, organizational, and developmental stressors and employed a range of coping strategies, including detaching, normalizing experiences, having a willingness to learn, and managing emotional reactions  experience as a tennis parent. Participants’ children were between the ages of 6 and 18 years of age  and were predominantly male (65.18%). Thirty-six participants’ children played ‘mini tennis’ (5–10 years) and had ratings between Red 4 (starting/lowest possible rating) and Green 1* (the best/highest possible rating) specific to ‘mini-tennis’. Ninety-nine participants’ children played junior tennis and had ratings between 10.2 (starting/lowest possible rating) and 2.2 . The highest  possible rating in British Tennis across junior and adult players is 1.1.Following institutional ethical approval, homogeneous purposeful sampling was used to recruit parents of British junior tennis players (aged 5–18 years). An email invitation was sent from the national governing body  to parents of an estimated 1,500 British tennis players who met the selection criteria . One hundred and thirty five parents  responded to this invitation and agreed to participate in the study (9.0% response rate). Most participants identified as being their child’s biological parent (97.77%), were in a relationship (94.77%), and had between 2 and 17 years , and provide worked examples. Once parents had read the introductory guide, they were asked to record up to five of the most prominent stressors that they had faced as a tennis parent. Participants were then asked to record the ways that they appraised each stressor  approach to hierarchical content analysis. This approach has been applied elsewhere in the literature e.g.,  to encoun = 342, and for coping effectiveness n = 646. Descriptive statistics  for the emotions experienced  and coping effectiveness were then calculated. Data were screened for parametric assumptions and detected the presence of outliers in happiness and excitement variables. Accordingly, when analyzing the data, sensitivity analyses were conducted without these extreme cases . These exclusions did not materially change the pattern of results. The main and interaction effects were the same, whilst two additional pairwise comparisons emerged as significant (these points are highlighted in the “Results” section). To complement the descriptive data, differences in emotions experienced as a function of stressor category and appraisal were explored using a 3  × 3  multivariate analysis (MANOVA). Differences in coping effectiveness as a function of stressor category, appraisal, and coping strategy were then assessed using a 3  × 3  × 3  analysis of variance (ANOVA). Any significant main or interaction effects were followed up with Bonferroni adjusted pairwise comparisons.Quantitative data analysis started by calculating the overall frequency with which each type of appraisal was reported . Providing sufficient power , the totIn accordance with guidance from Data analysis generated three general dimensions of parental stressors: (a) organizational; (b) competitive; and (c) developmental. These three dimensions contained a total of 20 higher order themes, 51 lower order themes see , and 342Eight higher order themes, 19 lower order themes see , and 155My daughter is a technically very able player, quite athletic, and plays really well in her 1–1 lessons and squads. Then she gets onto court in a tournament, playing against someone who is clearly a casual, 2 h-a-week player (not 10 h like my daughter!), and my daughter plays “down,” doesn’t use her technique, and loses. I wonder if it is even worth her putting all the hours training, if that is what happens in tournaments! (Parent 112).The presence of ‘other parents’ (15.56%) during competitions was another stressor and included lower order themes such as ‘bad behavior and attitude’ (6.67%), ‘interfering with play’ (5.19%), and ‘intimidating and aggressive behavior’ (3.70%). Parents reported specific examples such as: “Parents of other players providing guidance beyond acceptable encouragement” (Parent 111) and “abusive parents who shout at your child during the match” (Parent 65) as pertinent stressors associated with other parents. In addition, parents self-reported stressors that related to ‘watching a match’ (14.81%), particularly if they thought their child should win or would lose badly: “I find watching my son play a stressful experience, especially if I know the score…” (Parent 65). Parents also reported the ‘outcome of matches’ (11.85%) as a stressor, especially their ‘child losing a match’ (2.22%), ‘child’s reaction to match outcome’ (2.96%), and ‘consoling child/helping them to cope’ (5.19%). For instance, one parent stated: “If my child doesn’t win/play well he gets very upset and is sometimes physically sick. He thinks he’s letting everyone down… himself/me/coach” (Parent 53). Less frequently cited competition stressors included their ‘children’s psychological readiness to perform’ (6.67%) and ‘poor refereeing’ (2.96%).Six higher order themes, 25 low order themes see , and 135Beyond the financial and time commitments of junior tennis participation, parents identified ‘coaching and training’ (16.30%) and ‘organizing bodies’ (14.81%) as stressors. Lower order themes included the ‘lack of recognition and support’ (5.93%), ‘pressure of the rating system’ (4.44%), ‘problems with talent identification system’ (2.22%), and general ‘disorganization and management issues’ (2.22%) as organizational stressors. The following quote captures parents’ frustration with the current rating system:Too much emphasis for years on ratings, often non-reflective of ability, and until recently LTA refusal to acknowledge this. The LTA can’t see how the system is ‘abused’ by some players, and when you get your rating behind  virtually no opportunity to catch up (Parent 14).Other organizational stressors related to ‘tournaments’ (12.59%), and specifically ‘issues with entry, draws, and seedings’ (4.44%), ‘traveling to tournaments’ (3.70%), ‘poor organization/communication at tournaments’ (2.22%), ‘lack of umpire present’ (1.48%), and ‘tournament schedules’ (1.48%). As one parent wrote: “Referees being poorly organized, not getting players on, leaving long times in between matches, making mistakes in informing both players about starting times, not being friendly and helpful” (Parent 68). A small number of parents made reference to ‘injury’ related stressors (6.67%) and, in particular, ‘overuse injuries’ (3.70%). As one parent wrote: “My child has been constantly injured as a result of the amount of tennis training he has being taking part in” (Parent 41). Other parents cited ‘fear of injury’ (1.48%) and their ‘limited knowledge regarding injuries’ as stressors (1.48%).Six higher order themes, seven lower order themes see , and 44 I find it difficult to have to make choices and decisions about which tournaments my son should play and balancing out costs and aims from competition  (Parent 36).A small number of parents were concerned about the impact that tennis has on their ‘child’s education and social development’ (3.70%). As one parent wrote: “[Child’s name] spends 14 h a week doing sport outside school . I worry that this has an impact on both his school and his social development” (Parent 88). Beyond children’s development, some parents also reported stressors regarding their ‘child’s future in tennis’ (2.22%), the ‘impact of tennis on other sports/hobbies’ (1.48%), and their ‘child’s wellbeing and happiness’ (1.48%).Of the total 342 separate self-reported stressors, 115 (33.65%) were appraised as a harm/loss, 113 (33.04%) were appraised as a challenge, 105 (30.70%) were evaluated as a threat, and 9 (2.63%) were evaluated as a benefit. n = 8) and appraisals categorized as benefit (n = 9) were not included in analyses, resulting in a sample of 327 (two of the other stressors were appraised as benefit). Therefore, the means reported in text vary compared to F = 3.09, p = 0.001, F = 4.03, p < 0.001, F = 1.02, p = 0.436, M = 2.43 ± 1.42) compared to both developmental  and organizational stressors . In addition, in the analyses with the extreme cases removed, greater anger was reported in organizational compared to developmental stressors . Other comparisons were non-significant. Regarding the appraisal categories, follow up comparisons indicated greater dejection  and anger  in harm appraisal compared to challenge  appraisal. In addition, in the analyses with the extreme cases removed, greater dejection was reported in harm appraisal compared to threat (M = 1.67 ± 1.33) appraisal . There was also greater excitement  and happiness  in challenge appraisal compared to harm  and threat appraisal . Other comparisons were non-significant. In sum, competitive stressors elicited greater anger compared to organizational and developmental stressors. Further, stressors appraised as harm elicited greater negative emotions  compared to challenge appraisals, while stressors appraised as a challenge elicited greater positive emotions  compared to both harm and threat appraisals.Parents reported moderate levels of anxiety and anger, low levels of dejection, and very low levels of excitement and happiness in relation to the stressors recalled see . Due to A total of 653 individual coping strategies were reported by parents, which were categorized into 79 lower order themes, 20 higher order themes, and three general coping dimensions see . Seven eEleven higher order themes, 49 lower order themes see , and 374Prior to the match I try and get him to realize that there will always be dodgy [line] calls that he needs to focus on his own game and realize that he is handing the game to the other child if he lets it get to him. He needs to challenge the calls and call the referee over if it is too bad (Parent 53).In addition to communicating with their child, parents regularly used ‘time management’ (24.44%) as a higher order coping strategy that consisted of ‘planning, logistics, and being organized’ (14.81%), ‘selective tournament entry’ (6.67%), ‘scheduling time with siblings’ (4.44%), and ‘sharing commitments with partner’ (4.44%). Similarly, parents also used ‘financial management’ (18.52%) as a coping strategy and, particularly, ‘budgeting’ (13.33%) as one mother self-reported:Looking to set up a small business alongside part time work so we have more money coming in and still be flexible for coaching and tournaments. But I will miss out on seeing my daughter play and the tournaments will be down to her dad (Parent 122).‘Information seeking’ (26.67%) was another frequently cited coping strategy, with a number of parents ‘seeking information from child’s coach’ (18.52%) as well as other key stakeholders . Some parents also used coping strategies such as ‘managing child’s tennis progress and development’ (16.30%), including ‘scheduling/enforcing a break from tennis’ (6.67%), ‘changing coach/training center’ (4.44%), and ‘employing a sport psychologist’ (3.70%) as explained in the following quote:Engaged external professional help [sport psychologist] for our child and ourselves, utilize preparation routines and put our child at the center of the solution and recognize it is not a quick fix, give them the mechanisms and create an environment that will support them to help themselves supported by a team including ourselves as parents (Parent 110).Less frequently cited higher order coping strategies included, ‘changing parenting behavior’ (14.81%), ‘reducing negative impact of others’ (8.15%), ‘involving the referee’ (8.15%), ‘preparation’ (6.67%), ‘problem solving’ (5.93%), and ‘overseeing child’s overall development’ (4.44%).Two hundred and twenty-nine coping strategies, 23 lower order themes, and seven higher order categories see  were chaI think about how much I love my children and how I want them to have as many different opportunities as possible. I think about the positive impact sport has had (and continues to have) on their self-esteem, confidence, motivation, determination, and discipline. They are aware of their bodies and how to stay healthy. I think about how sport has encouraged them to take risks, to try things, to learn how to cope with getting things wrong. They have benefitted from interacting with a wider circle of people through sport. I consider that the time I will get with them (of them wanting me around) is relatively short and I rationalize that I have plenty of time to treat myself later! Also, when I stop and add everything up and really think about it, I always come to the conclusion that even if I had more money I would spend it on them anyway! (Parent 11).Parents also regulated their internal responses to stressors by ‘seeking emotional support’ (19.26%), which consisted mainly of ‘talking about situation with other parents’ (8.15%) or ‘talking about situation with partner/friend’ (7.41%). Other higher order themes included ‘behavioral avoidance’ strategies (19.26%), which included ‘watching match with a limited view/further away’ (6.67%), ‘avoiding contact with other parents’ (5.93%), and ‘temporarily walking away’ (2.96%). One parent explained why she watches with a limited view: “I sit so there is an obstruction in the way of the court to limit my view – again this stops me living every point” (Parent 50). Parents also used ‘emotional regulation’ (14.07%) coping strategies such as ‘trying to keep calm’ (9.63%) and ‘deep breathing’ (5.19%), as one parent disclosed: “If I go [to tournaments/matches] I try to take deep breaths and can’t wait for it to be over and go home” (Parent 87). Less frequently cited higher order coping strategies included ‘distraction’ (9.63%), ‘cognitive avoidance’ (8.89%), and ‘acceptance’ (6.67%). For instance, one parent explained how he charts matches  as a distraction technique: “I have started charting matches for something to focus on and then share stats with him sometime after match as part of conversation about how he felt and what the stats say” (Parent 130).Two higher order themes, seven lower order themes see , and 43 I removed myself from the match and walked away to get a coffee. [I was] angry and also feeling very concerned for my daughter who had done everything she is asked to when this happens but who was basically being bullied and cheated on court – disgraceful! Such inconsistency from official to official from tournament to tournament (Parent 3).In a small number of cases, parents ‘stopped child playing tennis’ (1.48%). For instance, one parent wrote: “I supported my son but asked him to stop playing. The pressure was painful to watch and no one cares” (Parent 129). A small number of parents also attempted to cope by ‘venting emotions’ (8.89%). This higher order category was made up of lower order themes such as ‘complaining’ (6.67%), ‘arguing’ (1.48%), and ‘crying’ (0.74%).n = 374), the most effective higher order coping strategy was ‘managing child’s tennis development and progress’ (M = 7.41 ± 1.84), which included moderately effective lower order strategies such as ‘changing coach/training center’ (M = 7.83 ± 1.60), ‘scheduling/enforcing break from tennis’ (M = 7.00 ± 2.26), and ‘employing a sport psychologist’ (M = 6.83 ± 1.17). In addition, ‘reducing negative impact of others’ (M = 6.93 ± 1.71), ‘time management’ (M = 6.59 ± 2.03), and ‘overseeing child’s overall development’ (M = 6.75 ± 2.25) were perceived as moderately effective higher order strategies. Other higher order strategies such as ‘communicating with child’ (M = 5.93 ± 2.30) included a combination of moderately effective  and ineffective lower order strategies . Similarly, within the ‘changing parenting behavior’ (M = 5.72 ± 2.73) higher order theme, ‘allowing child to make own choices’ (M = 7.80 ± 1.92) was moderately effective, whilst ‘punishing child’s behavior’ (M = 4.25 ± 2.66) was considered to be a moderately ineffective strategy. ‘Involving the referee’ (M = 4.64 ± 2.73) and ‘preparation’ (M = 4.50 ± 2.59) were considered to be the most ineffective mastery higher order coping strategies.As seen in n = 229), ‘behavioral avoidance’ (M = 6.62 ± 2.15) was considered to be the most effective higher order strategy, with lower order strategies such as ‘avoiding contact with other parents’ (M = 7.58 ± 1.68) and ‘watching match with a limited view/further away’ (M = 7.33 ± 1.66) considered as moderately effective. Another higher order theme ‘cognitive reappraisal’ (M = 6.41 ± 2.08) was perceived as moderately effective, and included particularly effective lower order themes such as ‘focusing on benefits of tennis participation’ (M = 7.25 ± 1.16) and ‘focusing on processes not outcomes’ (M = 7.33 ± 1.21). Similarly, ‘seeking emotional support’ (M = 6.15 ± 1.68), ‘emotional regulation’ (M = 6.08 ± 1.85), ‘acceptance’ (M = 6.12 ± 2.74) and ‘distraction’ (M = 6.47 ± 2.20) were moderately effective higher order strategies and ‘distraction with another task during a match’  was considered as a particularly effective lower order theme (M = 7.11 ± 1.96). In contrast, cognitive avoidance (M = 4.54 ± 2.44) was perceived to be moderately ineffective.Turning attention toward internal regulation coping strategies (n = 43) such as ‘behavioral disengagement’ (M = 5.31 ± 3.05) was considered moderately effective. In contrast, ‘venting emotions’ (M = 4.00 ± 2.85) was perceived as a relatively ineffective coping strategy. Parents also considered ‘not watching the match/training’ (M = 4.77 ± 3.09) to be a moderately ineffective strategy and ‘complaining’ (M = 3.92 ± 3.06) was perceived as the least effective coping strategy within this coping dimension.Higher order goal withdrawal strategies (M = 6.10 ± 2.32). Due to low numbers, benefit appraisals (n = 15) were not included in statistical analyses, resulting in a sample of 631 strategies. Therefore, the means reported in text vary compared to F = 0.85, p = 0.430, F = 1.69, p = 0.186, F = 6.01, p = 0.003, M = 6.20 ± 2.27) and internal regulation (M = 6.15 ± 2.03) strategies compared to goal withdrawal (M = 4.77 ± 2.98). In terms of the two-way interactions, there was: (a) a significant interaction between stressor category and appraisal, F = 3.69, p = 0.006, F = 3.69, p = 0.006, F = 0.27, p = 0.898, F = 1.57, p = 0.154, Overall, the 646 coping strategies were considered by parents to be moderately effective  compared to organizational , stressors only ; and (b) competition, but not organizational or developmental, stressors were managed more effectively following challenge appraisals  compared to both harm  and threat  appraisals.The two interaction effects were followed up with adjusted pairwise comparisons. First, regarding stressor category and appraisal: (a) challenge, but not harm or threat, appraisals were managed more effectively for competition stressors  compared to competition , stressors only ; and (b) organizational, but not competitive or developmental, stressors were managed more effectively by mastery  and internal regulation  strategies compared to goal withdrawal .Second, regarding stressor category and coping strategy: (a) mastery, but not internal regulation or goal withdrawal, coping was more effective for organizational . Focusing first on the relationship between emotions, coping, and coping effectiveness, mastery coping strategies (n = 374) were considered to be the most effective coping strategy and were used when parents reported moderate levels of anxiety, low levels of dejection and anger, and very low levels of excitement and happiness (see n = 229) also experienced moderate levels of anxiety, low levels of anger and dejection, and very low levels of excitement and happiness. In contrast, parents who used goal withdrawal strategies (n = 43) reported high levels of anxiety, moderate levels of anger and dejection, and very low levels of excitement and happiness , internal regulation (n = 113) and goal withdrawal (n = 28) coping strategies were used when parents experienced moderate levels of anxiety and anger, moderate to low levels of dejection, and very low levels of excitement and happiness in response to competition stressors. Of these strategies, internal regulation was considered to be most effective. Mastery (n = 52) and internal regulation (n = 33) coping strategies were used when parents experienced moderate levels of anxiety; low levels of dejection and anger; low to very low levels of excitement, and very low levels of happiness when facing developmental stressors. Goal withdrawal strategies (n = 2) were used when parents experienced high level of anxiety and dejection and moderate levels of anger. Mastery coping strategies (n = 158) were used when parents reported moderate levels of anxiety, low levels of dejection and anger, and very low levels of excitement and happiness when facing organizational stressors. Internal regulation strategies (n = 83) were used when parents reported moderate levels of anxiety and anger, low levels of dejection, and very low levels of excitement and happiness. Finally, goal withdrawal strategies (n = 13) were used when parents experienced high anxiety and anger, moderate levels of dejection, and very low levels of excitement in relation to organizational stressors. Mastery coping strategies were the most effective way of coping with both organizational and developmental stressors.The aim of this study was to build on the existing sport parent research through a thorough investigation of psychological stress among parents of competitive British tennis players. As such, the current study extends existing research on the stressors that parents experience , the wayn = 135) to date of the situations that British tennis parents appraise as taxing or exceeding their resources. In line with previous studies  in the current study is concerning given the implications that these types of appraisal have for parents’ experiences within youth sport contexts. Research with athletes has found positive associations between threat appraisals and mastery avoidance, performance approach, and performance avoidance goals as well as challenge appraisals and mastery goals e.g., . In addiThe present study was also the first to examine the range of emotions  that arise during sport parents’ stress transactions. Findings add to existing sport parent research i.e.,  by highlBuilding on the aforementioned points, our findings suggest that the emotions parents experience influence the coping strategies they select. For instance, parents in the current study tended to use internal regulation or mastery coping strategies when they experienced moderate to low levels of unpleasant emotions  and goal withdrawal strategies when they experienced moderate to high levels of unpleasant emotions . From a practical perspective, these findings suggest that reducing levels of unpleasant emotions  may enable parents to select more adaptive coping strategies . Although the mechanisms influencing this proposed relationship are not fully understood, it may be that experiencing less unpleasant emotions (particularly anxiety) reduces cognitive interference and enables parents to select a more effective coping strategy .Turning attention toward coping strategies, novel insights have been reached in this study regarding the most effective coping strategies parents used in response to competition, organizational, and developmental stressors. For example, our findings suggest that organizational stressors  were managed more effectively by mastery and internal regulation strategies when compared to goal withdrawal strategies. Further, when appraised as a challenge, competition stressors were managed more effectively compared to organizational, but not developmental, stressors. These findings are consistent with n = 135). Challenges to engage parents with busy lifestyles were expected but researchers should carefully consider how to attract even more representative samples of a sport’s parent community in future work. Finally, although nomothetic methods have afforded greater understanding of tennis parents’ stress as a collective, more specific and idiosyncratic insights remain constrained. For example, exploring stress transactions among parents at different ages/stages of their child’s sporting journey (see The current study and its applied implications should be considered in light of several limitations and insights that may enrich further research. First, only those stressors that were pertinent for parents at the time of data collection were explored. While this was a methodologically reasonable decision given the scope of this study, it does overlook the dynamic and recursive nature of stressors and stress more broadly. Future longitudinal research is needed to monitor stressors over time and build a more accurate and detailed picture of parents’ experiences. Use of diaries, think aloud protocols, or video assisted interviewing may assist in this respect. It would also be interesting to consider how parents’ level of experience or previous coping attempts influence their appraisals, emotions, and coping strategies. Second, the current study focused on primary appraising but secondary appraising is also an important part of stress transactions and one that can influence emotions and other outcomes (e.g., well-being, rney see  would buTo conclude, this study used a mixed method design to provide unique insights to various components of psychological stress among parents of British tennis players. Furthermore, exploring the relationships and interactions between each stage of stress transactions provided a number of novel insights into the most effective ways of mediating the relationships between appraisal and emotions and of managing the emotions arising from a stressor . Such inThe datasets generated for this study are available on request to the corresponding author.This study was carried out in accordance with the recommendations of the Loughborough University ethics committee with informed consent from all subjects. All subjects gave informed consent in accordance with the Declaration of Helsinki. The protocol was approved by the Loughborough University Ethics committee.CH was responsible for the conceptualization and management of research program. FD contributed to the study design and planning. LF was responsible for data collection. ST and MS analyzed the data. CH, ST, FD, and MS were responsible for manuscript preparation.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.


Statistical tests  document independence from phylogeny, and a previously unrecognized strong and significant correlation of δ13C enrichment with body mass for all mammalian herbivores. A single-factor body mass model outperforms all other single-factor or more complex combinatorial models evaluated, including for physiological variables (metabolic rate and body temperature proxies), and indicates that body mass alone predicts δ13C enrichment. These analyses, spanning more than 5 orders of magnitude of body sizes, yield a size-dependent prediction of isotopic enrichment across Mammalia and for distinct digestive physiologies, permitting reconstruction of foregut versus hindgut fermentation for fossils and refined mean annual palaeoprecipitation estimates based on δ13C of mammalian bioapatite.Carbon isotopic signatures recorded in vertebrate tissues derive from ingested food and thus reflect ecologies and ecosystems. For almost two decades, most carbon isotope-based ecological interpretations of extant and extinct herbivorous mammals have used a single diet–bioapatite enrichment value (14‰). Assuming this single value applies to all herbivorous mammals, from tiny monkeys to giant elephants, it overlooks potential effects of distinct physiological and metabolic processes on carbon fractionation. By analysing a never before assessed herbivorous group spanning a broad range of body masses—sloths—we discovered considerable variation in diet–bioapatite δ Stable isotope analysis is a powerful tool to reconstruct ancient ecologies and ecosystems, as it is independent of morphology and directly reflects dietary ecology. Because the carbon that animals use to synthesize different tissues relates directly to the ingested food , dietarlization , has beent foods –6). If tδ13C diet–bioapatite enrichment for herbivores across a wide diversity of mammal clades (including non-ungulates and a herbivore group never before assessed—sloths). Isotope enrichment was determined through controlled feeding experiments or constrained diet analyses to test the prevailing assumption that a single enrichment pattern holds for all plant-eating mammals, regardless of life-history attributes or ecology. If it does not, we seek to find and test explanatory variables to predict this value.This study evaluates 2.Choloepus [δ13C diet–bioapatite enrichment As described in Darwin's ‘Voyage of the Beagle’, fossil native mammals from South America include the ‘strangest animals ever discovered’ , p. 80. holoepus ). Some oholoepus . Thus, d3.δ13C of enamel and dentine bioapatite is considered equivalent if a primary signal is preserved, because any bioapatite  is in isotopic equilibrium with blood bicarbonate [δ13C of enamel and ivory of elephants in protocol tests  relative to organic tissues. In addition, the carbonate radical of bioapatite forms from blood bicarbonate, derived primarily from ingested carbohydrates, the main source of carbon in herbivorous diets ,14. Bioaarbonate . In modearbonate . For modarbonate –19), shol tests  from the Huachipa Zoo  kept under controlled and homogeneous feeding conditions  and Nothrotheriops shastensis (Gypsum and Rampart Caves)), recovered in association with their dung , and therefore it is the only specimen discussed further. Values of We analysed δnditions . Becauseeir dung . Dung δ1 mammals , as corr mammals ). Of theBradypus variegatus, n = 5) has an average δ13Cbioapatite value of −18.65‰ ± 1, which, compared to the δ13C of its diet at the zoo (−28.67‰ ± 1.79), results in a Choloepus hoffmanni, n = 10) has an average δ13Cbioapatite value of −14.08‰ ± 0.66, representing a 13C-enrichment of 12.62‰ ± 0.68 relative to the δ13C of its diet (−26.37‰). The δ13Cbioapatite (−12.46‰) of the extinct ground sloth M. darwinii is on average 15.63‰ ± 0.51 (15.12‰ to 16.13‰) 13C-enriched relative to its diet determined from faeces (−27.66‰ ± 0.49). The high 13C-enrichment of Mylodon's bioapatite relative to its diet places this taxon at the uppermost extreme of the Our results  showed tSus scrofa) to 14.65‰ in cattle (Bos taurus), whereas the range of variation observed in Perissodactyla spans from 13.2‰ in the zebra (Equus burchelli) to 14.4‰ in the black rhinoceros (Diceros bicornis). The range of Mus musculus, has the lowest Microtus ochrogaster, has a Oryctolagus cuniculus, has a Ailuropoda melanoleuca (Carnivora); koala, Phascolarctos cinereus ; and three-toed sloth (Folivora: Xenarthra), cluster near the lower end of the observed Placed in a broader mammalian context, results for three sloth taxa span a range of e figure , encompa4.δ13C values of diets in the wild , a series of physiologically correlated parameters were regressed against 4 yield, diversity and abundance of digestive tract microorganisms) were not available for most taxa with known values of Aiming to find explanatory variables correlated to the broad range of  figures  and 3. Ir2 = 0.62 , p-value = 0.0002; r2 = 0.78, p-value = 0.008) versus hindgut fermenters  (D > 0.5). Its exclusion in a secondary analysis, however, did not significantly alter the coefficient values; in fact, it makes the relationship even stronger , we also performed generalized linear model analyses based on Akaike information criterion (AICc) tests, to assess whether a single variable, reduced model or various model subsets were better supported by the data than a complete global model that includes all the potential predictors (Body mass shows a strong and significant positive correlation with = 0.003) . We test= 0.003) . Regressstronger . Based oedictors . Three medictors .Table 2a,b). Although no correlations were found between r2 = 0.89, p-value = 0.01) and not for hindgut fermenters or all mammalian herbivores . However, a regression analysis of average rectal temperature and body mass reveals that this correlation in foregut fermenters also is not independent of body mass . Rates of metabolic biochemical reactions are controlled by temperature [independently of body mass. Analytical experiments to propose and test specific mechanistic explanations for how body temperature, independent of or in association with factors driven by body mass, might affect Comparing different models of trait evolution, mammals, ). There rbivores c,d. Howeperature , but basδ13C enrichment that occurs between dietary input and metabolic CO2  has been attributed to digestive physiology [4) production [13C-depleted by almost 40‰ relative to the ingested diet, is a by-product gas during CO2 reduction [ɛ*), is predicted to result from the interaction of variables such as the capacity of the fermentative vat, amount and diversity of microorganisms living in it, and metabolic activity of the microorganisms [The ysiology , in partoduction . Methaneeduction , which ieduction . As a co. The substantial deviation from the predicted One taxon with a much lower than expected ficiency .4 production. The type of food selectivity (e.g. strict herbivory versus omnivory) might also play a role in controlling The house mouse was the smallest (approx. 20 g) mammal evaluated, and its ody size . In volearticles . Finallyus diets . A compaspecimen , more daEucalyptus spp. [Cecropia and Ficus spp. and in general are highly selective in their food choice, avoiding leaves of other tree species that are only moderately abundant on their home range [Bradypus (but not Choloepus) in captivity is so low [Bradypus), which can result in lower rates of CH4 production by reducing the fermentation activity of gastrointestinal symbionts [Choloepus has a larger Bradypus shows an even more variable and lower overall daily body temperature than Choloepus [Bradypus (by one-third) than in Choloepus [Ficus elastica), the food fed to the two-toed sloth included spinach and other greens, quinoa, sweet potatoes, carrots and pellets of Purina Dog Chow® , explained as owing to long particle mean retention times [Bradypus, is shorter.Besides the mouse and giant panda, the other two mammals with substantially lower activity , the addtus spp. , whereasme range . This sume range ), and mis so low . Finallyymbionts . In markholoepus ,36. In aholoepus . Moreovel origin –40. ConsBradypus . Both a Bradypus ,34,41 anon times . If so, Bos taurus. In general, roughage-eating ruminants have the most complex digestive tract of all mammalian herbivores, with a well-developed forestomach, small caecum and large populations of microorganisms in the rumen [Most artiodactyls and perissodactyls herein had y masses . The onlhe rumen ,44. This mammals . AlthougLoxodonta africana, shows a slightly lower 4 production (l day−1) per unit body mass [M. darwinii has an estimated body mass (approx. 1600 kg) only half that of an elephant, it possesses an even higher Mylodon also had a foregut-fermenting digestive tract. This type of digestive strategy would explain the high Mylodon, as now expected given the steeper slope of the regression model for foregut fermenters compared to hindgut fermenters. In fact, our regression model for foregut fermenters alone predicts a higher Mylodon from the analysis  artiodactyl [13C data of N. batesi from the Ituri Forest showed an average signature of −25.6‰. The use of the 14‰ 13C of the plant diet for this species as −39.6‰, lower than any plant ever recorded in that forest  calculations founded on δer study . Becauserbivores ,47, a boMylodon was a highly methanogenic foregut fermenter. Mylodon, a narrow-muzzled sloth interpreted as a selective feeder based on snout anatomy [Mylodon  to show even larger Lestodon armatus [As the value of  anatomy , is now  armatus . Sloths  armatus , showing