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

{"title":"Molecular cloning and functional characterization of mitochondrial RNA splicing 2 in fish Megalobrama amblycephala, and its potential roles in magnesium homeostasis and mitochondrial function","authors":"Ling Zhang,&nbsp;Zi-Shang Liu,&nbsp;Yan-Zou Dong,&nbsp;Chao-Fan He,&nbsp;Ding-Dong Zhang,&nbsp;Guang-Zhen Jiang,&nbsp;Wen-Bin Liu,&nbsp;Xiang-Fei Li","doi":"10.1016/j.cbpa.2024.111727","DOIUrl":"10.1016/j.cbpa.2024.111727","url":null,"abstract":"<div><p>Mitochondrial function can be regulated by ion channels. Mitochondrial RNA splicing 2 (Mrs2) is a magnesium ion (Mg²⁺) channel located in the inner mitochondrial membrane, thereby mediating the Mg²⁺ influx into the mitochondrial matrix. However, its potential role in regulating the Mg homeostasis and mitochondrial function in aquatic species is still unclear. This study molecularly characterizes the gene encoding Mrs2 in fish <em>M. amblycephala</em> with its functions in maintaining the Mg homeostasis and mitochondrial function verified. The <em>mrs2</em> gene is 2133 bp long incorporating a 1269 bp open reading frame, which encodes 422 amino acids. The Mrs2 protein includes two transmembrane domains and a conserved tripeptide Gly-Met-Asn, and has a high homology (65.92–97.64%) with those of most vertebrates. The transcript of <em>mrs2</em> was relatively high in the white muscle, liver and kidney. The inhibition of <em>mrs2</em> reduces the expressions of Mg²⁺ influx/efflux-related proteins, mitochondrial Mg content, and the activities of mitochondrial complex I and V in hepatocytes. However, the over-expression of <em>mrs2</em> increases the expressions of Mg²⁺ influx/efflux-related proteins, mitochondrial Mg content, and the complex V activity, but decreases the activities of mitochondrial complex III and IV and citrate synthase in hepatocytes. Collectively, Mrs2 is highly conserved among different species, and is prerequisite for maintaining Mg homeostasis and mitochondrial function in fish.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141914641","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":"IGF-1 and myostatin-mediated co-regulation in skeletal muscle and bone of Daurian ground squirrels (Spermophilus dauricus) during different hibernation stages","authors":"Jie Zhang ,&nbsp;Huiping Wang ,&nbsp;Huajian Yang ,&nbsp;Yong Kong ,&nbsp;Shenhui Xu ,&nbsp;Kai Dang ,&nbsp;Shanfeng Jiang ,&nbsp;Yunfang Gao","doi":"10.1016/j.cbpa.2024.111716","DOIUrl":"10.1016/j.cbpa.2024.111716","url":null,"abstract":"<div><p>Muscle and bone are cooperatively preserved in Daurian ground squirrels (<em>Spermophilus dauricus</em>) during hibernation. As such, we hypothesized that IGF-1 and myostatin may contribute to musculoskeletal maintenance during this period. Thus, we systematically assessed changes in the protein expression levels of IGF-1 and myostatin, as well as their corresponding downstream targets, in the vastus medialis (VM) muscle and femur in Daurian ground squirrels during different stages. Group differences were determined using one-way analysis of variance (ANOVA). Results indicated that the co-localization levels of IGF-1 and its receptor (IGF-1R) increased by 50% during the pre-hibernation period (PRE) and by 35% during re-entry into torpor (RET) compared to the summer active period (SA). The phosphorylation level of FOXO1 in the VM muscle increased by 50% in the torpor (TOR) group and by 82% in the inter-bout arousal (IBA) group compared to the PRE group. The phosphorylation level of SGK-1 increased by 54% in the IBA group and by 62% in the RET group compared to the SA group. In contrast, the protein expression of IGF-1 and phosphorylation levels of PI3K, Akt, mTOR, and GSK3β in the VM muscle showed no obvious differences among the different groups. β-catenin protein expression was up-regulated by 84% in the RET group compared to the SA group, while the content of IGF-1 protein, correlation coefficients of IGF-1 and IGF-1R, and phosphorylation levels of PI3K, Akt, and GSK3β in the femur showed no significant differences among groups. Regarding myostatin and its downstream targets, myostatin protein expression decreased by 70% in the RET group compared to the SA group, whereas ActRIIB protein expression and Smad2/3 phosphorylation in the VM muscle showed no obvious differences among groups. Furthermore, Smad2/3 phosphorylation decreased by 58% in the TOR group and 53% in the RET group compared to the SA group, whereas ActRIIB protein expression in the femur showed no obvious differences among groups. Overall, the observed changes in IGF-1 and myostatin expression and their downstream targets may be involved in musculoskeletal preservation during hibernation in Daurian ground squirrels.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141890995","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":"Embryonic thermal challenge is associated with increased stressor resiliency later in life: Molecular and morphological mechanisms in the small intestine","authors":"David L. Beck,&nbsp;Elizabeth R. Gilbert,&nbsp;Mark A. Cline","doi":"10.1016/j.cbpa.2024.111724","DOIUrl":"10.1016/j.cbpa.2024.111724","url":null,"abstract":"<div><p>Developing chick embryos that are subjected to increased incubation temperature are more stressor-resilient later in life, but the underlying process is poorly understood. The potential mechanism may involve changes in small intestine function. In this study, we determined behavioral, morphological, and molecular effects of increased embryonic incubation temperatures and post-hatch heat challenge in order to understand how embryonic heat conditioning (EHC) affects gut function. At 4 days post-hatch, duodenum, jejunum, and ileum samples were collected at 0, 2, and 12 h relative to the start of heat challenge. In EHC chicks, we found that markers of heat and oxidative stress were generally lower while those of nutrient transport and antioxidants were higher. Temporally, gene expression changes in response to the heat challenge were similar in control and EHC chicks for markers of heat and oxidative stress. Crypt depth was greater in control than EHC chicks at 2 h post-challenge, and the villus height to crypt depth ratio increased from 2 to 12 h in both control and EHC chicks. Collectively, these results suggest that EHC chicks might be more energetically efficient at coping with thermal challenge, preferentially allocating nutrients to other tissues while protecting the mucosal layer from oxidative damage. These results provide targets for future studies aimed at understanding the molecular mechanisms underlying effects of embryonic heat exposure on intestinal function and stressor resiliency later in life.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141903686","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":"Potency and specificity of amiloride and its analogues on branchial sodium fluxes in freshwater trout and goldfish","authors":"Adalto Bianchini ,&nbsp;Chris M. Wood","doi":"10.1016/j.cbpa.2024.111715","DOIUrl":"10.1016/j.cbpa.2024.111715","url":null,"abstract":"<div><p>There is a consensus that electroneutral Na⁺/H⁺ exchangers (NHEs) are important in branchial Na⁺ uptake in freshwater fish. There is also widespread belief, based on mammalian data, that EIPA [5-(N-ethyl-N-isopropyl)-amiloride]], and HMA [5-(<em>N</em>,<em>N</em>-hexamethylene)-amiloride)] are more potent and specific in blocking Na⁺ uptake than amiloride. We evaluated this idea by testing the three drugs at 10⁻⁷ to 10⁻⁴ M, <em>i.e.</em> 0.1 to 100 μM in two model species, rainbow trout (<em>Oncorhynchus mykiss</em>) and goldfish (<em>Carassius auratus</em>), using ²²Na⁺ to measure unidirectional Na⁺ influx and efflux rates. In both species, the potency order for inhibiting unidirectional Na⁺ influx was HMA &gt; amiloride &gt; EIPA (IC₅₀ values in the 10–70 μM range), very different from in mammals. At 100 μM, all three drugs inhibited Na⁺ influx by &gt;90% in both species, except for amiloride in goldfish (65%). However, at 60–100 μM, all three drugs also stimulated unidirectional Na⁺ efflux rates, indicating non-specific effects. In trout, HMA and EIPA caused significant increases (2.1- to 2.3-fold) in efflux rates, whereas in goldfish, significant efflux elevations were greater (3.1- to 7.2-fold) with all three drugs. We conclude that the inhibitory potency profile established in mammals does not apply to the NHEs in fish gills, that non-specific effects on Na⁺ efflux rates are a serious concern, and that EIPA and HMA offer no clear benefits in terms of potency or specificity. Considering its much lower cost, we recommend amiloride as the drug of choice for <em>in vivo</em> experiments on freshwater fishes.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141876809","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":"Elevated temperature impairs gonadal development by suppressing the expression of the genes for kisspeptin, GnRH1 and GTH subunits in Nile tilapia Oreochromis niloticus","authors":"Azmaien Naziat ,&nbsp;S.M. Majharul Islam ,&nbsp;Joya Chakrabarty ,&nbsp;Bilal Ahamad Paray ,&nbsp;Md Mahiuddin Zahangir ,&nbsp;Hironori Ando ,&nbsp;Md Shahjahan","doi":"10.1016/j.cbpa.2024.111714","DOIUrl":"10.1016/j.cbpa.2024.111714","url":null,"abstract":"<div><p>Temperature is a preeminent factor in the regulation of fish reproduction and hinders gonadal development beyond a specific threshold. To comprehend the molecular mechanism responsible for reproductive suppression at different temperature, expression of the genes encoding kisspeptin (<em>kiss2</em>), gonadotropin-releasing hormone (<em>gnrh1</em>) and their receptors (<em>gpr54, gnrh1r</em>) in the brain, and the gonadotropin (GTH) subunits (<em>fshb</em> and <em>lhb</em>) in the pituitary were studied in juvenile Nile tilapia (<em>Oreochromis niloticus</em>) along with gonadal histology. Fish were acclimatized to three distinct temperatures, including 31 °C, 34 °C and 37 °C for 14 days. The mRNA levels of <em>kiss2, gpr54, gnrh1,</em> and <em>gnrh1r</em> were significantly decreased at 37 °C compared to 31 °C and 34 °C in the both sexes. In parallel, the expression level of <em>fshb</em> in the both sexes and <em>lhb</em> in the female were significantly lower at 37 °C in the pituitary. Histologically, the gonads of both sexes had normal growth of gametes at control temperature (31 °C), whereas the spermatogenesis and oocyte maturation were slowed down and atretic oocytes were found in the ovary at 37 °C acclimation temperature. Taken together, the results imply that elevated temperature beyond the specific threshold may have a negative impact on reproduction by suppressing the gene expressions of kisspeptin/GnRH1/GTH system and eventually restrains normal growth and maturation of gametes in the both sexes of Nile tilapia.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141876808","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":"Corticosterone treatment results in fat deposition and body mass maintenance without effects on feeding behaviour or immunity in female lizards (Tropidurus catalanensis)","authors":"Débora Meyer de Almeida Prado ,&nbsp;Aymam Cobo de Figueiredo ,&nbsp;Alan Siqueira Lima ,&nbsp;Fernando Ribeiro Gomes ,&nbsp;Carla Bonetti Madelaire","doi":"10.1016/j.cbpa.2024.111712","DOIUrl":"10.1016/j.cbpa.2024.111712","url":null,"abstract":"<div><p>Throughout life, animals must maintain homeostasis while coping with challenging events. The period after reproduction can be challenging for oviparous females to maintain homeostasis since they direct most of their energy stores to vitellogenesis, possibly increasing the vulnerability to stressors. Changes in glucocorticoids' (GC) secretion promote various behavioural and physiological adjustments daily and to restore balance after facing stressors. However, when GC are elevated for extended periods, which usually occurs in response to chronic exposure to stressors, they can affect feeding behaviour and suppress the immune function. We aim to elucidate the effects of chronic corticosterone (CORT) exposure on feeding behaviour, body condition and immune function in female lizards, <em>Tropidurus catalanensis</em>, in the post-reproductive period. Thirty animals were divided into three groups: 1. Control (no experimental procedure performed); 2. Empty Implant (animals implanted with empty silastic tube); and 3. CORT Implant (animals implanted with silastic tube filled with CORT, with a chronic continuous release for at least a week). CORT plasma levels feeding behaviour, body condition (body index [BI] and fat index [FI]), leukocyte count, and several immune function variables (bacterial killing ability [BKA], hemagglutination titer, phytohemagglutinin [PHA] immune challenge and leukocyte count) were evaluated. After implantation, CORT treated animals maintained stable body mass through the experiment, while Control and Empty Implant groups displayed weight loss. In the CORT treated animals, there was also a positive relation between BI and FI, and higher FI when compared to groups 1 and 2. No effects of CORT were observed on feeding behaviour nor on the immune function.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141861737","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":"Deciphering the gut microbiota of zebrafish, the most used fish as a biological model: A meta-analytic approach","authors":"Estefanía Garibay-Valdez ,&nbsp;Cinthia Alejandra Olivas-Bernal ,&nbsp;Francisco Vargas-Albores ,&nbsp;Marcel Martínez-Porchas ,&nbsp;Diana Marbella García-Godínez ,&nbsp;Diana Medina-Félix ,&nbsp;Luis Rafael Martínez-Córdova ,&nbsp;Francesco Cicala","doi":"10.1016/j.cbpa.2024.111713","DOIUrl":"10.1016/j.cbpa.2024.111713","url":null,"abstract":"<div><p>A meta-analytic approach deciphered the taxonomic profile of the zebrafish gut microbiota at different developmental stages. Data (16S rDNA) were systematically searched in databases, selecting those with intestine samples of fish not exposed to a particular treatment or challenge (<em>e.g.,</em> pathogens, dietetic tests, xenobiotics, <em>etc.</em>) and obtaining 340 samples to be processed. Results revealed marked differences between the developmental phases. Proteobacteria was the dominant phylum in the larval phase, with a relative abundance of 90%, while the rest of the phyla did not exceed 2%. Vibrio, Aeromonas, Plesiomonas, Pseudomonas, Shewanella, and Acinetobacter were the dominant genera in this phase. Transitional changes were observed after the larvae stage. Proteobacteria still registered high abundance (48%) in the juvenile phase, but Fusobacteria (40%) and Bacteriodota (5.9%) registered considerable increases. Genera, including Cetobacterium, Plesiomonas, Aeromonas, Vibrio, and Flavobacterium, dominated this stage. The phyla Proteobacteria (48%) and Fusobacteria (35%) were strongly established in the adult phase. Cetobacterium was registered as the most abundant genus, followed by Aeromonas, Acinetobacter, Plesiomonas, Vibrio, and ZOR0006 (Firmicutes; 6%). In conclusion, the composition of the intestinal microbiota of zebrafish is consistently determined by two primary phyla, Proteobacteria and Fusobacteria; however, this composition varies depending on the developmental stage. Cetobacterium and Aeromonas are the most relevant genera in juveniles and adults. Finally, these results reveal a consistent pattern of certain bacterial groups in the zebrafish microbiota that could help shape gnotobiotic models (colonized with a specific known bacterial community) or synthetic microbiota (<em>in vitro</em> assembly of microbes), among other approaches.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141794164","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":"Involvement of the gut microbiota in the metabolic phenotypes of two sympatric gerbils","authors":"Jing Wen ,&nbsp;Wenting Li ,&nbsp;Tingbei Bo ,&nbsp;Boyang Ding ,&nbsp;Xueying Zhang ,&nbsp;Dehua Wang","doi":"10.1016/j.cbpa.2024.111710","DOIUrl":"10.1016/j.cbpa.2024.111710","url":null,"abstract":"<div><p>Temporal niche partitioning is a crucial strategy for sympatric species to avoid predation and competition for habitat space and food resources. This study investigated the effect of the gut microbiota on the metabolic rhythms of two sympatric gerbil species (<em>Meriones unguiculatus</em> and <em>Meriones meridianus</em>) to test the hypothesis that the oscillatory patterns of microbiota may not fully mirror those of the host's metabolism. <strong>Experiment 1</strong> compared the circadian metabolic and gut microbiota rhythms of <em>M. unguiculatus</em> (<em>n</em> = 12) and <em>M. meridianus</em> (n = 12) and measured the subjects' body temperatures and environmental temperature preferences. In <strong>Experiment 2.1</strong>, six <em>M. meridianus</em> gerbils were treated with antibiotics, and in <strong>Experiment 2.2</strong>, 21 <em>M. unguiculatus</em> gerbils (seven per treatment) were randomly gavaged with saline or a gut microbiota suspension from either <em>M. unguiculatus</em> or <em>M. meridianus</em>; their metabolic rhythms were subsequently measured. The results showed that the two gerbils had different metabolic phenotypes that determined activity heterogeneity and contributed to their coexistence. The relative abundances of <em>Bacteroidetes</em>, <em>Actinobacteria</em>, and <em>Cyanobacteria</em> in <em>M. meridianus</em> varied rhythmically in parallel with the daily metabolic rate, which was significantly higher at night than during the day. The rhythm of the metabolic rate was not noticeable in <em>M. unguiculatus</em>. However, in <em>M.unguiculatus</em>, the relative abundances of <em>Firmicutes</em>, <em>Bacteroidetes</em>, <em>Proteobacteria</em>, and <em>Verrucomicrobia</em> were significantly higher during the day than at night, while <em>Cyanobacteria</em> exhibited the opposite pattern. Antibiotic treatment significantly weakened the metabolic rhythms of <em>M. meridianus</em>, and the circadian rhythms slowly recovered after stopping antibiotic gavage. However, after transplanting <em>M. meridianus</em>' gut microbiota into <em>M. unguiculatus</em>, the metabolic rate of <em>M. unguiculatus</em> was not significantly different from that of the control groups. Our hypothesis was partly supported: the microbiota was only partially involved in regulating the metabolic rhythms of gerbils, and other factors could compensate for the effect of the gut microbiota on host metabolic rhythms. This finding underscores the complexity of host–microbiota interactions and highlights the need for further exploration into the multifaceted mechanisms governing host metabolic regulation.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141789906","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":"Odorant transport in a hagfish","authors":"Todor G. Cross ,&nbsp;Olivia C. Mayo ,&nbsp;Graham S. Martin ,&nbsp;Matthew P. Cross ,&nbsp;David K. Ludlow ,&nbsp;Katharine H. Fraser ,&nbsp;Jonathan P.L. Cox","doi":"10.1016/j.cbpa.2024.111711","DOIUrl":"10.1016/j.cbpa.2024.111711","url":null,"abstract":"<div><p>Odorant transport is of fundamental and applied importance. Using computational simulations, we studied odorant transport in an anatomically accurate model of the nasal passage of a hagfish (probably <em>Eptatretus stoutii</em>). We found that ambient water is sampled widely, with a significant ventral element. Additionally, there is a bilateral element to olfactory flow, which enters the single nostril in two narrow, laminar streams that are then split prior to the nasal chamber by the anterior edge of the central olfactory lamella. An appendage on this lamella directs a small portion (10–14%) of the overall nasal flow to the olfactory sensory channels. Much of the remaining flow is diverted away from the sensory channels by two peripheral channels. The anterior edge of the central olfactory lamella, together with a jet-impingement mechanism, disperses flow over the olfactory surfaces. Diffusion of odorant from bulk water to the olfactory surfaces is facilitated by the large surface area:volume ratio of the sensory channels, and by a resistance-based hydrodynamic mechanism that leads to long residence times (up to 4.5 s) in the sensory channels. With increasing volumetric flow rate, the rate of odorant transfer to the olfactory surfaces increases, but the efficiency of odorant uptake decreases, falling in the range 2–6%. Odorant flux decreases caudally across the olfactory surfaces, suggesting <em>in vivo</em> a preponderance of olfactory sensory neurons on the anterior part of each olfactory surface. We conclude that the hagfish has a subtle anatomy for locating and capturing odorant molecules.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1095643324001387/pdfft?md5=52a35d2ef35335ece11251bfb07e5ccc&pid=1-s2.0-S1095643324001387-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141789907","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}

{"title":"Using heart rate and acceleration biologgers to estimate winter activity costs in free-swimming largemouth bass","authors":"Connor Reeve ,&nbsp;Kurtis A. Smith ,&nbsp;Andre Morin ,&nbsp;Paul A. Bzonek ,&nbsp;Steven J. Cooke ,&nbsp;Jacob W. Brownscombe","doi":"10.1016/j.cbpa.2024.111708","DOIUrl":"10.1016/j.cbpa.2024.111708","url":null,"abstract":"<div><p>Winter is a critical period for largemouth bass (<em>Micropterus nigricans</em>) with winter severity and duration limiting their population growth at northern latitudes. Unfortunately, we have an incomplete understanding of their winter behaviour and energy use in the wild. More winter-focused research is needed to better understand their annual energy budget, improve bioenergetics models, and establish baselines to assess the impacts of climate warming; however, winter research is challenging due to ice cover. Implantable tags show promise for winter-focused research as they can be deployed prior to ice formation. Here, using swim tunnel respirometry, we calibrated heart rate and acceleration biologgers to enable estimations of metabolic rate (<em>Ṁ</em>O₂) and swimming speed in free-swimming largemouth bass across a range of winter-relevant temperatures. In addition, we assessed their aerobic and swim performance. Calculated group thermal sensitivities of most performance metrics indicated the passive physicochemical effects of temperature, suggesting little compensation in the cold; however, resting metabolic rate and critical swimming speed showed partial compensation. We found strong relationships between acceleration and swimming speed, as well as between <em>Ṁ</em>O₂ and heart rate, acceleration, or swimming speed. Jackknife validations indicated that these modeled relationships accurately estimate swimming speed and <em>Ṁ</em>O₂ from biologger recordings. However, there were relatively few reliable heart rate recordings to model the <em>Ṁ</em>O₂ relationship. Recordings of heart rate were high-quality during holding but dropped during experimentation, potentially due to interference from aerobic muscles during swimming. The models informed by acceleration or swimming speed appear to be best suited for field applications.</p></div>","PeriodicalId":55237,"journal":{"name":"Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1095643324001351/pdfft?md5=3dbd63ff933f604617dc4523a7f27a06&pid=1-s2.0-S1095643324001351-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768112","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}