Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology最新文献

{"title":"Assessing metabolite profiles of wild Swainson's thrushes (Catharus ustulatus) in different moult stages using a veterinary point of care device","authors":"Elena Tranze-Drabinia ,&nbsp;Vanessa Poirier ,&nbsp;Barbara Frei ,&nbsp;Kyle H. Elliott","doi":"10.1016/j.cbpa.2025.111912","DOIUrl":"10.1016/j.cbpa.2025.111912","url":null,"abstract":"<div><div>Migration and moult are both energetically demanding and have conflicting physiological requirements, therefore usually separated in time. In some species, individuals may interrupt their migration to moult at discrete stopover locations outside of their breeding grounds (i.e., moult-migration) leading to competing physiological demands for moult and migration as protein is needed both for feather regeneration and efficient migration. Here, we examine the plasma metabolite profiles between moulting and post-moulting migrants by using a point-of-care analyzer providing real-time data in the field. Post-moulting birds, who were on shorter migration stopovers, had significantly higher concentrations of aspartate aminotransferase, calcium, sodium, phosphorous, and total protein than moulting birds, which is consistent with higher metabolic demands during migration and depletion of protein due to feather regeneration during moult. Additionally, uric acid, creatine kinase, total protein, aspartate aminotransferase, and potassium – all indicative of protein catabolism, muscle damage, and dehydration – were higher in lighter birds (below a scaled mass index of 7–7.5) regardless of moult status, which is consistent with lower energy reserves reflecting nutritional stress. Together, these metabolite profiles, measured in situ at a banding station, provide real-time insight into how birds mitigate the physiologically competing demands of moult and migration at a peri-urban stopover.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111912"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144755173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abnormalities in trehalose homeostasis reduce autophagy, antioxidant and response to air exposure stress in Eriocheir sinensis","authors":"Anjun Xiang ,&nbsp;Jiayi Chen ,&nbsp;Chengyi Weng ,&nbsp;Chenxu Liu ,&nbsp;Jie Zhang ,&nbsp;Qing He ,&nbsp;Yongxu Cheng ,&nbsp;Xiaozhen Yang","doi":"10.1016/j.cbpa.2025.111898","DOIUrl":"10.1016/j.cbpa.2025.111898","url":null,"abstract":"<div><div>Trehalose, a key carbohydrate in crustaceans and insects, is important in enhancing stress resistance. However, its regulatory mechanisms and functions in Chinese mitten crabs (<em>Eriocheir sinensis</em>) remain unclear. This study was designed to explore the regulation mechanisms of trehalose anabolism by synthesizing dsRNA interference fragments to target trehalose-6-phosphate synthase (<em>TPS</em>) and trehalose hydrolase (<em>TREH</em>) genes, investigating the effects of endogenous trehalose anabolism, antioxidant function, and autophagy in crabs under air exposure stress (AES). First, dsRNAs were synthesized, and interference fragments (EGFP, dsTPS1, and dsTREH2) and the optimal interference duration (48 h) were screened by in vitro culture. Further in vivo experiments demonstrated that interference with <em>TPS</em> and <em>TREH</em> genes led to abnormal trehalose anabolism in crabs subjected to AES; following interference, the expression of <em>TPS</em> gene was significantly down-regulated, while that of trehalose transporters (<em>TRET</em>) genes was significantly up-regulated; in the hepatopancreas, the levels of trehalose and glucose (Glu) were notably increased, whereas their levels in the hemolymph were significantly decreased. Abnormalities in trehalose homeostasis led to down-regulated expression of autophagy genes (<em>ATG4B</em>, <em>ATG7</em>, <em>ATG13</em>, <em>Beclin1</em>) and its activation pathway, MAPK signaling pathway genes (<em>ERK</em>, <em>JNK</em>, <em>p38</em>); this was accompanied by a decrease in p38 protein level, which ultimately led to decreased antioxidant capacity, increased vacuolated cells, and disturbed cellular arrangement in hepatopancreatic tissues of crabs under AES; there was an up-regulation of the expression of genes such as catalase (<em>CAT</em>), superoxide dismutase (<em>SOD</em>), and glutathione peroxidase (<em>GSH-PX</em>), which resulted in significant increase in the cumulative mortality rates.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111898"},"PeriodicalIF":2.1,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144555894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bim gene regulation in hypoxic stress response of blunt snout bream (Megalobrama amblycephala): Mechanisms of apoptosis, oxidative stress, and transcriptional control by c-Ets-2","authors":"Siyu Ding ,&nbsp;Yahui Feng ,&nbsp;Loic Kemmadzong Foning ,&nbsp;Jie Chen ,&nbsp;Guodong Zheng ,&nbsp;Shuming Zou","doi":"10.1016/j.cbpa.2025.111913","DOIUrl":"10.1016/j.cbpa.2025.111913","url":null,"abstract":"<div><div>Despite its significant economic value, the blunt snout bream (<em>Megalobrama amblycephala</em>) is extremely sensitive to hypoxia. Derived from blunt snout bream gill filament cell lines, <em>Megalobrama amblycephala</em> gill (MAG) cells are closely linked to hypoxia, making them suitable for identifying related genes' hypoxia tolerance. This study explores the roles of the <em>Bcl-2</em> interacting mediator of cell death gene (<em>Bim</em>) in the gill tissues and MAG cells under hypoxic conditions. <em>Bim</em> expression increased significantly (<em>P</em> &lt; 0.05) after 24 h of hypoxia but decreased following reoxygenation. Overexpression of <em>Bim</em> significantly (P &lt; 0.05) upregulated the expression of pro-apoptotic genes <em>Bax</em> and <em>Caspase 3</em>, while downregulating the expression of the anti-apoptotic gene <em>Bcl-2</em>. Conversely, <em>Bim</em> interference exhibited an opposite trend. Hypoxia led to increased apoptosis and decreased mitochondrial membrane potential (MMP) in MAG cells, which was exacerbated by overexpression of <em>Bim</em>. In contrast, <em>Bim</em> interference attenuated apoptosis and prevented the decrease in MMP. ROS levels significantly (<em>P</em> &lt; 0.05) increased under hypoxic conditions, and <em>Bim</em> overexpression further elevated ROS production, whereas <em>Bim</em> interference reduced ROS levels. Antioxidant enzyme (SOD, CAT) activity decreased after hypoxia, which was exacerbated by <em>Bim</em> overexpression, while <em>Bim</em> interference slowed the decline of enzyme activity. The dual-luciferase reporter assay confirmed that the transcription factor c-Ets-2 regulates the expression of <em>Bim</em> by binding to the -GAGGAA site of the <em>Bim</em> promoter. This study highlights <em>Bim</em>'s key role in hypoxic stress and offers new insights into the hypoxic adaptation mechanisms of blunt snout bream.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111913"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144755186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short communication: Elevated testosterone correlates with enhanced innate immune function in a cooperatively breeding rodent","authors":"K.M.E. Wallace ,&nbsp;S.N. Venter ,&nbsp;N.C. Bennett ,&nbsp;D.W. Hart","doi":"10.1016/j.cbpa.2025.111911","DOIUrl":"10.1016/j.cbpa.2025.111911","url":null,"abstract":"<div><div>In many vertebrates, elevated testosterone is believed to compromise the immune function, reflecting a trade-off between reproduction and survival. However, such trade-offs may potentially be relaxed in cooperative breeders, where social conflict and sexual selection are reduced. We investigated the relationship between testosterone, cortisol, and innate immunity in captive male Damaraland mole-rats (<em>Fukomys damarensis</em>), a eusocial rodent with minimal aggression-driven reproductive competition. Using microbial killing assays (MKAs) and white blood cell counts as proxies of immune function, we found that urinary testosterone concentration was positively correlated with immune strength. Males with higher urinary testosterone concentrations exhibited significantly greater antimicrobial capacity and elevated total white blood cell counts. However, urinary testosterone was unrelated to independent immune cell differentials. While, reproductive status, age, body mass, and urinary cortisol concentrations had a limited effect on any immune metric. These findings, while correlative, challenge traditional endocrine-immune trade-off models and infer that, in this species, testosterone may signal condition rather than impose immunosuppressive costs.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111911"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-omics-based study on metabolic-physiological response to heat stress in rainbow trout (Oncorhynchus mykiss)","authors":"Yang Yang ,&nbsp;Yingjie Liu ,&nbsp;Wenzhi Liu ,&nbsp;Lin Han ,&nbsp;Fangying Yuan ,&nbsp;Jing Wang ,&nbsp;Song Wu ,&nbsp;Yanchun Sun ,&nbsp;Shicheng Han","doi":"10.1016/j.cbpa.2025.111903","DOIUrl":"10.1016/j.cbpa.2025.111903","url":null,"abstract":"<div><div>Global warming poses a critical survival challenge for cold-water economic fish, necessitating elucidation of their physiological and metabolic responses to heat stress. This study established a rainbow trout heat stress model using a gradual temperature increase protocol (from 16 °C to 20 °C over 8 days, followed by maintenance at 20 °C for 22 days) and investigated the adverse effects and adaptive strategies of rainbow trout under heat stress. Extensive congestion and steatosis observed in liver tissues suggested that heat stress induced inflammatory responses and dysregulation of lipid metabolism. Significant increases in antioxidant enzyme activities and reactive oxygen species levels (1.29-fold) indicated activation of the antioxidant defense system, and this response was insufficient to alleviate oxidative damage. Integrative transcriptomic and metabolomic analyses revealed that lipid metabolism was the most significantly altered biological process. Elevated prostaglandin D2 (1.64-fold change), driven by disruption of arachidonic acid metabolism, triggered inflammatory responses. Adaptive upregulation of linoleic acid and α-linolenic acid metabolism likely maintained membrane fluidity, enhancing the capacity for heat stress adaptation. Concurrently, adaptive activation of both <em>GPX4A</em> (6.73-fold change) and the heat shock proteins (<em>LOC118938277</em> and <em>hsp47</em>) likely mitigated oxidative damage associated with heat stress in the liver. Overall, this study advances the understanding of pathological injuries and adaptive strategies in rainbow trout under heat stress and identifies candidate genes for breeding heat-tolerant strains.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111903"},"PeriodicalIF":2.1,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144610364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survival and acute osmoregulatory response of grass carp under salinity stress","authors":"Zhu Zhu ,&nbsp;Shengjie Li ,&nbsp;Caixia Lei ,&nbsp;Tao Zhu ,&nbsp;Jing Tian ,&nbsp;Jinxing Du ,&nbsp;Shina Wei ,&nbsp;Hongmei Song","doi":"10.1016/j.cbpa.2025.111905","DOIUrl":"10.1016/j.cbpa.2025.111905","url":null,"abstract":"<div><div>Inland saline waters, widely distributed globally, impose stringent constraints on aquaculture owing to their high osmotic pressure, preventing most aquatic organisms from surviving. As the most extensively farmed freshwater fish worldwide, the grass carp (<em>Ctenopharyngodon idella</em>) is confined to freshwater habitats. The adaptation of this species to saline aquaculture holds significant ecological and economic potential; however, the mechanisms underlying its osmotic regulation in hypersaline environments remain poorly understood. In this study, juvenile grass carp with a mean body weight of 15.42 ± 0.96 g were subjected to acute salinity tolerance tests across six gradients (0, 4, 7, 10, 13, and 16 ppt). The 96 h median lethal salinity concentration (LC50) was first determined, followed by the evaluation of osmoregulatory dynamics through physiological-biochemical profiling and targeted quantification of salinity-responsive gene expression under acute stress conditions. Results showed mortality exhibited salinity-dependent escalation, and the LC50–96 h was 10.58 ppt. Under 24 h salinity exposure (0, 4, 7, and 10 ppt), grass carp exhibited salinity-dependent increases in serum electrolytes (Na⁺, Cl⁻, K⁺) and cortisol (<em>P</em> &lt; 0.05). Serum osmolality remained stable at 4 ppt and 7 ppt but increased significantly at 10 ppt. Serum prolactin showed progressive decline from 7 ppt. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in the liver, kidney, and gills showed salinity-stimulated upregulation (significant at 7 and 10 ppt). Immune-related enzymes, acid phosphatase (ACP) and alkaline phosphatase (AKP), increased at 4 and 7 ppt, whereas AKP activity declined at 10 ppt. Gill Na⁺/K⁺-ATPase (NKA) activity was significantly elevated at 10 ppt (<em>P</em> &lt; 0.01). Moreover, both gill and kidney structures exhibited significant alterations under 7 ppt and 10 ppt salinity stress. Specifically, the gill showed cracks in the filaments, chloride cell hyperplasia, and detachment of flattened epithelial cells; renal tubules were atrophic. The expression of ion transport-related genes <em>NKA</em> and solute carrier family 12 member 2 (<em>SLC12A2</em>) in the gills increased with increasing salinity; both genes showed significant differences at 7 ppt and 10 ppt, indicating their role in regulating osmotic pressure balance. This study provides a theoretical basis for the saline aquaculture technology and salt-tolerant variety development in grass carp.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111905"},"PeriodicalIF":2.1,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144627724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional enzymatic characterisation and microbiome analysis of the digestive tract of the green sea urchin Strongylocentrotus droebachiensis","authors":"Marie Koch ,&nbsp;Sylke Wohlrab ,&nbsp;Reinhard Saborowski","doi":"10.1016/j.cbpa.2025.111907","DOIUrl":"10.1016/j.cbpa.2025.111907","url":null,"abstract":"<div><div>The digestive system of sea urchins is well-described, but the biochemical properties of the individual organs are only insufficiently characterized. The digestive tract begins in the buccal cavity, surrounded by a biting apparatus called Aristoteles' lantern. It then forms a tubular structure, which runs two times around the body wall, ending at the aboral side of the animal. This main part of the digestive tube has been described histologically as the stomach (first loop, anticlockwise) and the intestine (second loop, clockwise). We characterized the enzymatic profile as well as the microbial composition of the stomach and the intestine of the green sea urchin <em>Strongylocentrotus droebachiensis</em>, an ecological and economical important arctic-boreal grazer. Using qualitative and quantitative enzyme activity assays on tissue of the stomach and intestine, we identified differences in the biochemical processes, primarily concerning the protein and lipid metabolism. The stomach expressed higher esterase and esterase/lipase activity, while the intestine showed predominantly high exopeptidase activity. Low carbohydrate degrading enzyme activity suggests that polysaccharide digestion, despite their abundance in the species' diet, may primarily occur extracellularly in the lumen of the digestive tube. Our enzymatic findings are complimented by metabarcoding of the microbial community and analysis of functional properties: We found microbial taxa possibly associated with nitrogen fixation and carbohydrate degradation. Nevertheless, the composition and potential functional genes of the microbial community were similar between the two organs, suggesting that they do not play an organ-specific role in digestive processes.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111907"},"PeriodicalIF":2.1,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144668978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Group size influences feeding behavior and the expression of appetite, stress, and neurotransmitter-related transcript expression in tiger barb (Puntigrus tetrazona)","authors":"Julianne M.D. King,&nbsp;Helene Volkoff","doi":"10.1016/j.cbpa.2025.111915","DOIUrl":"10.1016/j.cbpa.2025.111915","url":null,"abstract":"<div><div>Tiger barbs (<em>Puntigrus tetrazona)</em> are typical shoaling fish that can become stressed and aggressive when kept in small groups. To examine whether group size affects feeding, fish were housed in groups of 1, 2, 4, or 8 individuals per tank and monitored over a 10-day period. Overall feeding behavior, latency to feed, and the amount of food consumed were assessed daily. After 10 days under these conditions, fish were sampled for intestine and brain for transcript expression analyses. Genes examined included appetite regulators such as neuropeptide Y-<em>npy</em>, <em>orexin</em> and melanin-concentrating hormone-<em>mch</em> in the brain and cholecystokinin-<em>cck</em> and <em>ghrelin</em> in the intestine. We also analyzed brain expression of hormones related to social behavior and stress (oxytocin-<em>oxt</em>, corticotrophin-releasing factor-<em>crf</em> and thyrotropin-releasing hormone-<em>trh</em>) and genes related to the synthesis of serotonin (tryptophan hydroxylase-<em>tph</em>) and dopamine (tyrosine hydroxylase-<em>th</em>) and epinephrine (dopamine-β-hydroxylase- <em>dbh</em>). Isolated fish consumed significantly less food and exhibited longer latency to feed compared to all other groups. Fish housed in pairs also showed reduced intake and longer feeding latency relative to those in groups of 4. In the intestine, <em>ghrelin</em> expression was elevated in isolated fish relative to those in larger groups, while no differences were observed in <em>ccka</em> or <em>cckb</em> expression. In the brain, expression of orexigenic neuropeptides (<em>npy</em>, <em>mch</em>, and <em>orexin</em>) was higher in isolated and pair-housed fish compared to those in groups of 4 or 8. Expression of stress- and neurotransmitter-related genes (<em>crf</em>, <em>trh</em>, <em>th</em>, and <em>tph1</em>) was also significantly elevated in isolated fish. No significant group-size effects were found for <em>oxt</em>, <em>tph2</em>, <em>dbh</em>, or <em>cart</em> expression. Overall, our results suggest that small group sizes, particularly isolation, impair feeding behavior and upregulate orexigenic and stress-related gene expression, highlighting the importance of social environment in regulating physiological and behavioral responses in shoaling fish.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111915"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144763739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypoxia impairs survival and alters immune and iron metabolism gene expression during shark early ontogeny","authors":"Sandra Martins ,&nbsp;Jaquelino Varela ,&nbsp;Rute Felix ,&nbsp;Catarina Pereira Santos ,&nbsp;José Ricardo Paula ,&nbsp;Deborah M. Power ,&nbsp;Rui Rosa","doi":"10.1016/j.cbpa.2025.111904","DOIUrl":"10.1016/j.cbpa.2025.111904","url":null,"abstract":"<div><div>The global oxygen inventory has been declining worldwide, primarily due to climate change. The importance of oxygen for aerobic respiration and its homeostasis makes declining oxygen levels a concern, particularly during energy demanding lifecycle stages. The effects of low oxygen levels on neuroendocrine responses and immune competence of developing sharks were studied in the head and trunk tissues of early (EE; before pre-hatching) and late embryos (LE) of small-spotted catshark (<em>Scyliorhinus canicula</em>) under six days of deoxygenation (93 % O₂ of air saturation) and hypoxic conditions (26 % O₂). Catshark embryos were resilient to deoxygenation, with only a 10 % decline in survival compared to the control, and only the gene expression of melanotransferrin changed. Under hypoxia, growth was unaffected, but survival decreased by 31 % compared to the control in LE, highlighting an inadequate physiological response. Developmental stage affected the expression of hypoxia-inducible factor 1 alpha (<em>hif1a</em>), iron metabolism and immune-related genes, pointing to critical response mechanisms. The EE stage had an optimised stress response under hypoxia compared to LE, with the upregulation of the <em>hif1a</em> gene. The lack of a protective response and compromised immune-related functions under hypoxia in LE raise concerns about species survival under climate change. These findings highlight the need for further research on the likely resilience of sharks to environmental challenges.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111904"},"PeriodicalIF":2.1,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144621215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The development and plasticity of acid excretion mechanisms in early life stage red drum, Sciaenops ocellatus","authors":"Joshua Lonthair ,&nbsp;Andrew J. Esbaugh","doi":"10.1016/j.cbpa.2025.111910","DOIUrl":"10.1016/j.cbpa.2025.111910","url":null,"abstract":"<div><div>Ocean acidification (OA) has been shown to affect early life stage fishes in a variety of ways, including reduced survival and growth, and increased tissue damage. Yet, there is also substantial interspecies variability in the sensitivity of early life stage fishes to high CO₂, and it has been theorized that this may relate to the ontogeny of systemic acid-base regulatory pathways; an area that has been surprisingly understudied in obligate marine species. Here, we used an integrative set of approaches to describe the development and plasticity of acid excretion pathways in developing red drum (<em>Sciaenops ocellatus</em>), a marine fish native to the Gulf of Mexico. We observed mRNA expression of relevant transporters and ionocytes immediately post-hatch (36 h post-fertilization, hpf) with relatively stable abundance throughout the pre-metamorphic stages. Consistent with work in adults and seawater acclimated euryhaline larvae, we demonstrate strong co-localization of acid excretion proteins within a single epithelial ionocyte cell-type. Measurements of epithelial Δ[H]⁺, an indicator of proton efflux, showed that by 72 hpf larvae had CO₂-responsive EIPA-sensitive acid excretion, confirming the presence of sodium proton exchanger (NHE)-mediated acid excretion. Elevated mRNA expression of <em>nhe2</em> and <em>nhe3</em> was induced following exposure to 5500 and 12,000 μatm CO₂, which coincided with the absence of further survival effects relative to lower dose CO₂. Overall, these data confirm that red drum have fully functional epithelial acid excretion pathways in early life, and that plasticity in these pathways may offer survival benefits.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"308 ","pages":"Article 111910"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144735493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}