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

{"title":"Changes in thermal preference, respiratory and metabolic patterns in Tropidurus torquatus: Population responses from two distinct Brazilian biomes","authors":"Sofia L. B. da S. Matos ,&nbsp;Lays de Souza Porto ,&nbsp;Melissa Bars-Closel ,&nbsp;Fábio Cury de Barros ,&nbsp;Tiana Kohlsdorf ,&nbsp;Kenia C. Bícego ,&nbsp;Luciane H. Gargaglioni","doi":"10.1016/j.cbpa.2025.111871","DOIUrl":"10.1016/j.cbpa.2025.111871","url":null,"abstract":"<div><div>Variations in structural and climatic conditions of habitats, particularly in environmental temperatures, emerge as a pivotal determinant exerting broad influence on physiological processes, such as modifications in ventilation and metabolism within certain species. We investigated the thermal preference, ventilatory, and metabolic responses to acclimation in two Brazilian populations of the lizard <em>Tropidurus torquatus</em> — one population from the Pampa biome and the other from the restinga (sandbank) ecosystems in the Atlantic Forest biome. We divided lizards into three distinct acclimation temperatures (20 °C – ‘cold’, 25 °C – ‘warm’, and 30 °C – ‘hot’ regimes) and, after three weeks, recorded their preferred temperatures. Subsequently, we measured ventilation and metabolism in the same individuals at 20 °C, 25 °C, and 30 °C. Both populations exhibited similar responses to acclimation in thermal variables. However, in the extreme acclimation regimes, the Pampa population selects colder temperatures more frequently than the Restinga population. We did not detect any effect of acclimation or population on ventilation. In contrast, we identified changes in respiratory frequency likely related to changes in acclimation temperature regimes for both populations. In terms of metabolism, we recorded lower oxygen consumption in the Pampa population at warm and hot acclimation regimes. Our findings suggest that physiological responses to acclimation in <em>T. torquatus</em> may be intricately molded by the specific environmental contexts in which populations are situated. Animals originating from the southern population exhibit increased thermal responses – like the reduction of O₂ consumption when faced with 30 °C experimental temperature – potentially attributed to their exposure to more variable temperature regimes in their native habitat.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"306 ","pages":"Article 111871"},"PeriodicalIF":2.1,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143899916","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":"Polyamine dynamics and transcriptomic changes in honey bees (Apis mellifera, L.) during aging","authors":"Jelena Purać ,&nbsp;Elvira Vukašinović ,&nbsp;Marko Kebert ,&nbsp;Tatjana Čelić ,&nbsp;Srđana Đorđievski ,&nbsp;Jelena Spremo ,&nbsp;Ivan Pihler ,&nbsp;Danijela Kojić","doi":"10.1016/j.cbpa.2025.111870","DOIUrl":"10.1016/j.cbpa.2025.111870","url":null,"abstract":"<div><div>Honey bees (<em>Apis mellifera,</em> L.) play an important role in ecosystems due to their pollination, which directly impacts biodiversity and agricultural production. Understanding the biological mechanisms that determine bee aging is important for conserving bee populations and the ecosystems they serve. This study explored the dynamics of polyamine level changes and transcriptomic alterations during the aging of summer and winter worker bees. The present study's results indicate that the polyamine content in summer bees decreased overall with age, while winter bees exhibited a biphasic pattern, with an initial decrease followed by an increase in older individuals. These differences likely reflect distinct physiological needs during summer (work-intensive) and winter (survival-focused) periods. Transcriptomic analyses identified age-related changes, with key driver gene analysis highlighting critical genes associated with cuticle formation, venom activity, and polyamine metabolism, indicating structural and metabolic adaptations with age. KEGG pathway analysis identified enrichments in pathways related to peroxisome function, lipid metabolism, glycan degradation, lysosomal activity, and others underscoring shifts in cellular maintenance and energy regulation. This study underscores the complexity of polyamine dynamics and molecular adaptations in honey bee aging and provides a foundation for conserving bee populations and better understanding longevity across species.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"306 ","pages":"Article 111870"},"PeriodicalIF":2.1,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887692","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":"Role of the cell cycle-related gene cdk2 and its associated ceRNA network in sexual size dimorphism of Cynoglossus semilaevis","authors":"Xihong Li ,&nbsp;Jiacheng Wang ,&nbsp;Jiaqi Mai ,&nbsp;Yuqi Sun ,&nbsp;Wenjie Li ,&nbsp;Zhenyu Cai ,&nbsp;Wenteng Xu ,&nbsp;Zhangfan Chen ,&nbsp;Songlin Chen ,&nbsp;Na Wang","doi":"10.1016/j.cbpa.2025.111867","DOIUrl":"10.1016/j.cbpa.2025.111867","url":null,"abstract":"<div><div>Sexual size dimorphism (SSD) in <em>Cynoglossus semilaevis</em> affects its annual production and restricts aquaculture development. Our previous multi-omics data analysis showed that cell cycle genes and the relevant non-coding RNAs (ncRNAs) were closely involved in SSD regulation. In this study, we analyzed <em>cyclin-dependent kinase 2</em> (<em>cdk2</em>) gene together with its associated microRNA (miRNA) and long ncRNA (lncRNA) in <em>C. semilaevis</em>, predicting a competing endogenous RNA (ceRNA) regulatory network (MSTRG.24810.1-miR-460-cdk2) and verifying the targeting relationship using dual luciferase reporter assays. Expression profile analysis showed that <em>cdk2</em> and the lncRNA MSTRG.24810.1 were highly expressed in female gonad and muscle, and their expression levels increased from 3-month-old (3M) to 8M. On the other hand, their negative regulator miR-460-x displayed lower expression in female than in male. After miR-460-x mimic transfection in <em>C. semilaevis</em> ovarian cells, the expressions of <em>cdk2</em>, <em>cyclin E</em>, and MSTRG.24810.1 were significantly decreased and cell cycle transition through G1 to S phase was obviously blocked. <em>In vitro</em> and <em>in vivo</em> experiments also indicated that RNAi-mediated knock-down of <em>cdk2</em> caused down-regulation of MSTRG.24810.1 and other cell cycle related genes like <em>cyclin E</em>, <em>cyclin A</em>, <em>e2f1</em>, and <em>h2b</em>. Taken together, these results suggested that <em>cdk2</em> gene and its associated ceRNA network may affect sex growth difference and differentiation of <em>C. semilaevis</em> individuals <em>via</em> regulating cell division and proliferation. The study will not only expand our knowledge on SSD regulatory mechanism, but also help to make an application on promoting growth and development of the fish.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"305 ","pages":"Article 111867"},"PeriodicalIF":2.1,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143844663","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":"Transcriptional analysis reveals antioxidant, ion transport, and glycolysis mechanisms in Litopenaeus vannamei gills involved in the response to high alkali stress","authors":"Yiming Li ,&nbsp;Yucong Ye ,&nbsp;Xiaoyi Zhu ,&nbsp;Yuxing Wei ,&nbsp;Yan Li ,&nbsp;Zhen Sun ,&nbsp;Kai Zhou ,&nbsp;Pengcheng Gao ,&nbsp;Zongli Yao ,&nbsp;Qifang Lai","doi":"10.1016/j.cbpa.2025.111868","DOIUrl":"10.1016/j.cbpa.2025.111868","url":null,"abstract":"<div><div>Saline-alkali aquacultural systems have an important role in improving the economic output of the aquacultural industry. However, the survival rate of shrimp in intensive aquacultural systems is affected by alkalinity fluctuations. This study explored the ion transport and molecular responses of the whiteleg shrimp <em>Litopenaeus vannamei</em> to short-term high alkaline stress (96 h). The results showed that survival rate decreased significantly with time, hemolymph osmotic pressure and oxygen consumption dropped sharply after peaking at 48 h, and ammonia excretion followed a non-monotonic pattern, with an initial decline followed by a subsequent increase. Analysis of key physiological indicators revealed that urea nitrogen continued to accumulate, antioxidant (SOD and CAT) and glycolytic (PFK and LDH) enzymes were significantly activated, but ion regulatory enzymes (Na⁺/K⁺-ATPase) were severely suppressed. Gill histopathology showed typical injuries (such as gill filament shrinkage, vacuolation, and hemocytopenia). Furthermore, transcriptome analysis confirmed that high alkali stress activated insulin signaling pathway and glycolysis-related genes (e.g., upregulating <em>PFK</em> and <em>GLUT</em> expression). These results indicate that the high alkalinity causes an ion imbalance, changes the ammonia transport process, and activates the glycolysis pathway. These conclusions provide a theoretical basis for the subsequent development for the saline-alkaline aquacultural of <em>Litopenaeus vannamei</em>.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"306 ","pages":"Article 111868"},"PeriodicalIF":2.1,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860209","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":"Participation of membrane-initiated cortisol effects on the rapid acclimation of rainbow trout (Oncorhynchus mykiss) to increased salinity","authors":"Jorge Eduardo Aedo ,&nbsp;Daniela Aravena-Canales ,&nbsp;Juan Antonio Valdés ,&nbsp;Alfredo Molina","doi":"10.1016/j.cbpa.2025.111866","DOIUrl":"10.1016/j.cbpa.2025.111866","url":null,"abstract":"<div><div>Cortisol, a fundamental slow-acting hormone in teleosts, plays a crucial role in acclimating to changes in saline environments. Cortisol effects are associated with its interaction with intracellular glucocorticoid (GR) and mineralocorticoid (MR) receptors, which subsequently regulate gene expression through the cortisol-receptor complex. This mechanism is known as a genomic cortisol signaling and has been studied extensively. However, recent studies have begun to explore a membrane-initiated cortisol pathway that is initiated on the cellular surface, revealing its critical role in the initial metabolic adjustments during the physiological stress response. Nevertheless, the role of this novel membrane-mediated cortisol action during acclimatization to saline environments remain to be elucidated. To investigate this, an <em>in vivo</em> assay was performed in which juvenile rainbow trout were maintained in freshwater (FW) (0.1 ppt), intraperitoneally injected with vehicle, cortisol or cortisol-BSA (three hours of treatment), and transferred to saline water (15 ppt) for one additional hour. Samples of blood and gills were obtained from each fish in order to measure the plasma cortisol, glucose and chloride concentrations, as well as the expression levels of the <em>gr1</em>, <em>gr2</em>, <em>mr</em>, and key osmoregulatory genes. Membrane-initiated cortisol action increased plasma glucose and chloride levels in fish after one hour of saline transfer in comparison with the vehicle group. Furthermore, cortisol exerts a novel regulatory influence on the expression of <em>gr2,</em> as well as tight junction proteins <em>claudin10e</em> and <em>cldn30</em> in the gills. In contrast, other osmoregulation-related genes, such as <em>cftr and nkcc1</em>, are exclusively mediated by genomic cortisol signaling. These results suggest that membrane-initiated cortisol action plays a significant role in the rapid acclimation of fish to changes in salinity environments.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"306 ","pages":"Article 111866"},"PeriodicalIF":2.1,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887694","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":"Compensatory sensory mechanisms in naïve blind cavefish navigating novel environments after lateral line ablation","authors":"Sofia Z. Marketaki ,&nbsp;Fidji Berio ,&nbsp;Valentina Di Santo","doi":"10.1016/j.cbpa.2025.111863","DOIUrl":"10.1016/j.cbpa.2025.111863","url":null,"abstract":"<div><div>Fishes navigating complex aquatic environments rely on various sensory systems, primarily the lateral line system and vision, to guide their movements. One interesting example is the Mexican blind cavefish (<em>Astyanax mexicanus</em>). This fish relies on the lateral line system as it navigates through the environment without the aid of sight. It is unclear, however, how they might navigate through a novel environment when the lateral line is not functional. In this study, we used high-speed videography to quantify whether naïve blind cavefish alter locomotor behavior, navigation patterns, and the use of body and fins to explore a novel environment with obstacles when the lateral line is ablated. Blind cavefish with an intact lateral line demonstrated deliberate slower exploratory movements and navigated around obstacles with fewer touching events. Conversely, fish with ablated lateral line exhibited increased speed to potentially improve flow sensing. Fish with an ablated lateral line also touched obstacles more often, suggesting a reliance on fin and snout mechanoreception for navigation. These results show the blind cavefish have compensatory sensory mechanisms to navigate novel environments when their major sensory system is not functioning.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"305 ","pages":"Article 111863"},"PeriodicalIF":2.1,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837898","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":"Cardiovascular responses of embryonic alligator (Alligator mississippiensis) exposed to 10% O2 and sodium cyanide (NaCN), a chemoreflex-inducing compound","authors":"John Eme ,&nbsp;Gil Martinez Bautista ,&nbsp;Audrey Keneda ,&nbsp;Kevin Tate ,&nbsp;George Melancon ,&nbsp;Dane A. Crossley II","doi":"10.1016/j.cbpa.2025.111865","DOIUrl":"10.1016/j.cbpa.2025.111865","url":null,"abstract":"<div><div>The possibly interactive effects of changes in atmospheric respiratory gases (hypoxia or hypercapnia) <em>and</em> pharmacological chemoreceptor stimulation have not been assessed previously. We present a series of experimental protocols investigating embryonic alligators' capacity to modulate a cardiovascular neural chemoreflex response to a known chemoreceptor stimulant, sodium cyanide (NaCN). We incubated alligator embryos in 21 % (normoxia) and 10 % O₂ (hypoxia) beginning at 20 % of embryonic incubation, and at 70 % and 90 % of incubation we measured heart rate and blood pressure responses to NaCN. These NaCN responses also included examining the effects of NaCN after 1-h exposure to 10 % O₂., ganglionic blockade with hexamethonium chloride and α-adrenergic blockade with phentolamine. Injections of NaCN into the chorioallantoic artery caused a rapid bradycardia followed by a secondary hypertension, which can be attributed to an autonomic nervous system mediated reflex loop. We compared the heart rate response to injections of 1 mg kg⁻¹ NaCN before and after a 1-h 10 % O₂ exposure, and it was clear that embryonic alligators lacked capacity to change the intensity of cardiovascular responses to this compound. Hexamethonium greatly lessened the rapid bradycardia, and at 90 % of incubation, the secondary hypertensive response to NaCN appeared due to α-adrenergic stimulation, as phentolamine lessened the response. Collectively, data indicate that while a cardiovascular chemoreflex can be induced by NaCN, the heart rate response lacks plasticity and is not modulated by hypoxic incubation in embryonic alligators.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"305 ","pages":"Article 111865"},"PeriodicalIF":2.1,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833810","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":"Adjustments to energy provisioning and oxidative balance in response to temperature in a wild passerine","authors":"Pierre Deviche ,&nbsp;Karen Sweazea ,&nbsp;Nadia Upah","doi":"10.1016/j.cbpa.2025.111864","DOIUrl":"10.1016/j.cbpa.2025.111864","url":null,"abstract":"<div><div>Climate change and urbanization are associated with elevated ambient temperature (T_a). This increase may negatively impact organisms by creating conditions that are outside their resilience limits, but the physiological mechanisms that limit phenotypic plasticity in response to T_a variation remain poorly understood. We investigated these mechanisms in captive House Finches, <em>Haemorhous mexicanus</em>, a common native resident of rural and urban environments. We exposed finches to temperatures either slightly below the species' lower critical temperature (constant 20 °C; COOL group) or close to its upper critical temperature (daily min. 27 °C, daily max. 35 °C; WARM group) for two weeks. Birds in the COOL group ate more than birds in the WARM group, which is consistent with the prediction that cool T_a exposure increased the metabolic rate. However, finches of the two groups did not differ with regard to their body masses, fat reserves, or blood concentrations of ketone bodies, uric acid, and erythrocytic peroxidized lipids. Thus, exposure to the two experimental treatments did not result in major metabolic differences between groups. Acute stress caused by handling and restraint for 30 min decreased plasma uric acid, which may have been associated with its utilization as a free radical scavenger and so may have decreased stress-associated oxidative damage. Acute stress also increased plasma ketone bodies, suggesting increased lipid oxidation. These stress-related metabolic changes did not differ in the COOL and WARM groups, indicating within the range of T_a to which birds were exposed that temperature did not affect the birds' physiological sensitivity to acute stress.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"305 ","pages":"Article 111864"},"PeriodicalIF":2.1,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791680","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":"Respiratory flow and tidal volume scale with body mass in sea turtles but not breath duration","authors":"Kino Sakai ,&nbsp;Tomoko Narazaki ,&nbsp;Masanori Mori ,&nbsp;Tomomi Matsumoto ,&nbsp;Kagari Aoki ,&nbsp;Andreas Fahlman ,&nbsp;Kentaro Q. Sakamoto","doi":"10.1016/j.cbpa.2025.111855","DOIUrl":"10.1016/j.cbpa.2025.111855","url":null,"abstract":"<div><div>The ventilatory capacity of sea turtles is an important factor in their diving ability because they spend most of their time submerged. However, there is limited information on the relationship between the ventilatory capacity and body mass of sea turtles. To investigate the allometric scaling of the functional ventilatory capacity, we measured respiratory flow, tidal volume, and breath duration of spontaneous breaths in 40 sea turtles from 3 species (loggerhead, <em>Caretta caretta</em>; green, <em>Chelonia mydas</em>; hawksbill, <em>Eretmochelys imbricata</em>) of various body sizes (range: 0.7–120.6 kg) on land and in water. The results showed that the ventilatory capacity did not differ on land or in water. The respiratory flow and tidal volume increased with body mass with an allometric exponent of 0.76–0.80 and 0.87–0.89, respectively. In contrast, the breath duration and the ratio of tidal volume to the maximum lung volume were constant. These results suggest that sea turtles increase respiratory flow by increasing tidal volume with increasing body mass rather than prolonging breath duration, which may allow them to reduce the surface interval to breathe. This study improves the understanding of the ventilatory capacity of sea turtles.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"305 ","pages":"Article 111855"},"PeriodicalIF":2.1,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143797223","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 histological and molecular response of acute hypoxia and reoxygenation in rainbow trout and steelhead","authors":"Xiao-Qun Chen ,&nbsp;Yan-Gen Zhou ,&nbsp;Kun-Tong Jia ,&nbsp;Yu-Hang Wang ,&nbsp;Zhen Zhao ,&nbsp;Yue-Huan Zhang ,&nbsp;Zhi-Tao Huang ,&nbsp;Qin-Feng Gao ,&nbsp;Yun-Wei Dong ,&nbsp;Shuang-Lin Dong","doi":"10.1016/j.cbpa.2025.111854","DOIUrl":"10.1016/j.cbpa.2025.111854","url":null,"abstract":"<div><div>Hypoxia is a critical environmental stressor affecting fish survival and physiological function. Landlocked rainbow trout (<em>Oncorhynchus mykiss</em>) and anadromous steelhead (<em>Oncorhynchus mykiss</em>), two ecotypes of the same species, exhibit distinct physiological adaptations to fluctuating oxygen levels. To investigate their responses to acute hypoxia in these fish, brain histology and transcriptome analyses were conducted before stress, after hypoxia (12 and 24 h), and after reoxygenation (24 h). The results showed that the number of vacuolated nerve cells in the brain increased with the duration of hypoxia and decreased after 24 h of reoxygenation in both fish. RNA-Seq analysis identified 8409 differentially expressed genes (3952 in rainbow trout and 4457 in steelhead), one hypoxia-related module (MEred), and two significantly expressed gene clusters (cluster 3 in rainbow trout and cluster 8 in steelhead) through differential expression analysis, weighted gene co-expression network analysis (WGCNA), and Mfuzz clustering. KEGG pathway enrichment analysis revealed that signal transduction, immune response, angiogenesis, and apoptosis were significantly influenced by hypoxia in both fish. Distinct hypoxic responses were observed: in rainbow trout, ferroptosis, necroptosis, phosphatidylinositol signaling, calcium, and apelin signaling pathways were enriched, whereas in steelhead, the enriched pathways included platelet activation, Rap1, PI3K-Akt, Hippo, relaxin, and oxytocin signaling. Steelhead display marginally greater hypoxia tolerance than rainbow trout, although the difference is minimal, likely owing to their classification as the same species. These findings provide insight into the physiological and molecular mechanisms underlying hypoxia and reoxygenation stress in salmonids, contributing to a broader understanding of oxygen homeostasis in fish.</div></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":"305 ","pages":"Article 111854"},"PeriodicalIF":2.1,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143789429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}