Journal of Experimental Biology最新文献

{"title":"Precision and accuracy of the dynamic endocast method for measuring volume changes in XROMM studies.","authors":"Elska B Kaczmarek, Ellen Y Li, John G Capano, Peter L Falkingham, Stephen M Gatesy, Elizabeth L Brainerd, Ariel L Camp","doi":"10.1242/jeb.249420","DOIUrl":"https://doi.org/10.1242/jeb.249420","url":null,"abstract":"<p><p>The X-ray Reconstruction of Moving Morphology (XROMM) workflow enables precise and accurate measurement of the 3D skeletal kinematics underlying animal behaviors. The dynamic endocast method built upon that workflow to measure the rate of volume change within a bounded region of interest. We measured the precision and accuracy of the dynamic endocast method, using a fish oropharyngeal cavity as a case study. Despite overestimating instantaneous absolute volume, the endocast method was found to measure rate of volume change with high accuracy. Importantly, it underestimated the rate of volume change, indicating that these measurements are conservative. We tested how variables such as alpha value and locator number impacted the accuracy of the endocast method. While the appropriate values for these variables are likely different for each application of the endocast method, we believe that our conclusions that the dynamic endocast method underestimates change in volume is generalizable.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accounting for the role of the gastro-intestinal tract in the ammonia and urea-N dynamics of freshwater rainbow trout on long-term satiation feeding.","authors":"Chris M Wood, Junho Eom","doi":"10.1242/jeb.249654","DOIUrl":"https://doi.org/10.1242/jeb.249654","url":null,"abstract":"<p><p>The contribution of the gut to the ingestion, production, absorption, and excretion of the extra ammonia and urea-N associated with feeding (\"exogenous\" fraction) has received limited prior attention. Analysis of commercial pellet food revealed appreciable concentrations of ammonia and urea-N. Long term satiation-feeding increased whole trout ammonia and urea-N excretion rates by 2.5-fold above fasting levels. Blood was sampled from the dorsal aorta, posterior, mid, and anterior sub-intestinal veins, as well as the hepatic portal vein in situ. Ammonia, urea-N, and fluid flux rates were measured in vitro using novel gut sac preparations filled with native chyme. The sacs maintained the extreme physico-chemical conditions of the lumen seen in vivo. Overall, these results confirmed our hypothesis that the stomach and anterior intestine+pyloric caecae regions play important roles in ammonia and urea-N production and/or absorption. There was a very high rate of urea-N production in the anterior intestine+pyloric caecae, whereas the posterior intestine dominated for ammonia synthesis. The stomach was the major site of ammonia absorption, and the anterior intestine+pyloric caecae region dominated for urea-N absorption. Model calculations indicated that >50% of the exogenous ammonia and urea-N excretion associated with satiation-feeding was produced in the anaerobic gut. This challenges standard metabolic theory used in fuel use calculations. The novel gut sac preparations gained fluid during incubation, especially in the anterior intestine+pyloric caecae, due to marked hyperosmolality in the chyme. Thus, satiation-feeding with commercial pellets is beneficial to the water balance of freshwater trout.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Testing hypotheses of skull function with comparative finite element analysis: three methods reveal contrasting results.","authors":"D Rex Mitchell, Stephen Wroe, Meg Martin, Vera Weisbecker","doi":"10.1242/jeb.249747","DOIUrl":"https://doi.org/10.1242/jeb.249747","url":null,"abstract":"<p><p>Comparative finite element analysis involves standardising aspects of models to test equivalent loading scenarios across species. However, regarding feeding biomechanics of the vertebrate skull, what is considered \"equivalent\" can depend on the hypothesis. Using 13 diversely-shaped skulls of marsupial bettongs and potoroos (Potoroidae), we demonstrate that scaling muscle forces to standardise specific aspects of biting mechanics can produce clearly opposing comparisons of stress or strain that are differentially suited to address specific kinds of hypotheses. We therefore propose three categories of hypotheses for skull biting mechanics, each involving a unique method of muscle scaling to produce meaningful results: those comparing (1) the skull's efficiency in distributing muscle forces to the biting teeth, via standardising input muscle force to skull size, (2) structural biting adaptation through standardising mechanical advantage to simulate size-independent, equivalent bites, and (3) feeding ecology affected by size, such as niche partitioning, via standardising bite reaction force.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulation of the sex pheromone detection by nutritional and hormonal signals in a male insect.","authors":"Evan Force, Caroline Suray, Christelle Monsempes, Annabelle Fuentes, Annick Maria, Stéphane Debernard","doi":"10.1242/jeb.249807","DOIUrl":"https://doi.org/10.1242/jeb.249807","url":null,"abstract":"<p><p>As in other animals, insects can modulate their odor-guided behaviors, especially sexual behavior, according to environmental and physiological factors such as the individual's nutritional state. This behavioral flexibility results from modifications of the olfactory pathways under the control of hormones. Most studies have focused on the central modulation of the olfactory system and less attention has been paid to the peripheral olfactory system. To understand how nutritional inputs influence the detection of sex pheromones in insects, we turned to the male moth Agrotis ipsilon for which the behavioral responsiveness to sex pheromones is dependent on diet and reproductive hormones, juvenile hormone (JH) and 20-hydroxyecdysone (20E). We demonstrated that a sugar-rich diet with sodium increases the sensitivity of olfactory receptor neurons to (Z)-7-dodecen-1-yl acetate, the major sex pheromone compound, and the antennal expression of the pheromone binding protein (PBP2) and the pheromone receptor (OR3). Such a diet also induces overexpression of the Methoprene-tolerant receptor to JH and underexpression of the ecdysone receptor to 20E in antennae. The diet-induced olfactory responses were maintained by treatment with Cucurbitacin B, a 20E antagonist, but were suppressed by the topic application of Precocene, a JH biosynthesis inhibitor. These findings reveal that a positive nutritional state enhances the sex pheromone detection through JH actions on the peripheral actors of the pheromone system in male moths. More broadly in insects, our study provides, for the first time, a neuronal and molecular basis of the dietary-dependent endocrine modulation of the peripheral olfactory system.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The metabolic cost of producing joint moments is greater at the hip than at the ankle.","authors":"Negin Fallah, Owen N Beck","doi":"10.1242/jeb.249738","DOIUrl":"10.1242/jeb.249738","url":null,"abstract":"<p><p>Older adults walk using their hips relatively more and their ankles relatively less than young adults. This 'distal-to-proximal redistribution' in leg joint mechanics is thought to drive the age-related increase in metabolic rate during walking. However, many morphological differences between hip and ankle joints make it difficult to predict how, or whether, the distal-to-proximal redistribution affects metabolic rate during walking. To address this uncertainty, we compared the metabolic rate of participants while they repeatedly produced isolated hip and ankle moment cycles on a dynamometer following biofeedback. Overall, participants produced greater joint moments at their ankle versus hip and correspondingly activated their largest ankle extensor muscle more than their largest hip extensor muscle. Cycle average muscle activation across other hip and ankle extensors was nondifferent. Despite producing greater joint moments using slightly more relative muscle activation at the ankle, participants expended more net metabolic power while producing moments at the hip. Therefore, producing joint extension moments at the hip requires more metabolic energy than that at the ankle. Our results support the notion that the distal-to-proximal redistribution of joint mechanics contribute to greater metabolic rate during walking in older versus young adults.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142828845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat sensitivity of sperm in the lizard Anolis sagrei.","authors":"Wayne Wen-Yeu Wang, Natalie R Page, Anthony M Strickler, Alicia K Kusaka, Alex R Gunderson","doi":"10.1242/jeb.249435","DOIUrl":"10.1242/jeb.249435","url":null,"abstract":"<p><p>The heat sensitivity of reproduction is a critical determinant of population persistence under climate change. However, the heat sensitivity of gametes has been much less studied relative to that of adults. We developed a method to measure the heat tolerance limits of lizard sperm cells, and used the method to test several aspects of sperm cell thermal biology in the brown anole lizard (Anolis sagrei). We estimated the repeatability of sperm traits by measuring heat tolerance and baseline motility of ejaculated sperm from the same individuals multiple times over 21 days. To investigate co-adaptation of sperm and adult thermal traits, we tested for a correlation between sperm heat tolerance and the heat tolerance of the adults that produced them. Furthermore, we tested for effects of episodic heat stress experienced by males on sperm performance. Sperm heat tolerance and motility were both repeatable, consistent with evolutionary potential, though there was clear evidence for environmental effects on these traits as well. Contrary to the expectation of thermal co-adaptation, we found no correlation between sperm and adult heat tolerance. A single, episodic extreme heat event experienced by adult males immediately impaired sperm motility, consistent with detrimental effects of adult heat stress on sperm stored within males. Our study adds to the mounting evidence that sperm are heat-sensitive and represent a vulnerability to global warming, but also suggest evolutionary potential for thermal adaptation at the gamete level.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142818291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial light at night impairs visual lateralisation in a fish.","authors":"Gaia De Russi, Cristiano Bertolucci, Tyrone Lucon-Xiccato","doi":"10.1242/jeb.249272","DOIUrl":"10.1242/jeb.249272","url":null,"abstract":"<p><p>Environmental light, particularly during early development, significantly influences lateralisation, the asymmetric information processing between brain hemispheres. We hypothesised that lateralisation could be affected by artificial light at night (ALAN), a widespread form of environmental pollution. In our experiment, we exposed eggs and larvae of zebrafish to either control or ALAN conditions and then tested them in a rotational test to assess motor lateralisation, and a mirror test to assess lateralisation in response to visual stimuli. The control group exhibited a significant lateralisation bias at the population level, prioritising the processing of visual information with their right hemisphere. In contrast, the zebrafish exposed to ALAN did not show this bias, leading to a notable reduction in lateralisation. Additionally, we found evidence of reduced individual differences in lateralisation in the ALAN group. Overall, our findings demonstrate that ALAN disrupts the natural lateralisation in fish larvae, possibly affecting their behaviour and survival.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142854281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flexibility of cutaneous evaporative water loss in response to hydration in pregnant prairie rattlesnakes (Crotalus viridis) and their neonates.","authors":"Robin E Bedard, Savannah J Weaver, Haley A Moniz, Scott M Boback, Emily N Taylor","doi":"10.1242/jeb.247964","DOIUrl":"10.1242/jeb.247964","url":null,"abstract":"<p><p>Viviparous snakes may be particularly vulnerable to predicted increases in drought because of the high hydric costs associated with embryonic development and gestation, and their reliance on limited free-standing bodies of water or rain events for hydration. Drought will have negative implications for viper populations if females become increasingly water stressed and resorb developing embryos to conserve bodily water. We conducted a study to investigate the importance of drinking water in late-term pregnancy and its effect on cutaneous evaporative water loss (CEWL). We measured hydration and water loss in response to supplemental hydration during the final stages of embryonic development and gestation in arid-adapted prairie rattlesnakes (Crotalus viridis). Our goal was to assess how supplemental water affects hydration status and water loss (via CEWL) of females during and after pregnancy, and of their neonates before and after their first ecdysis. Supplemental hydration of pregnant C. viridis improved their hydration state and their neonates were also born more hydrated than those from control mothers, showing that they transfer water to neonates via the placenta even over a very short period in the late stages of pregnancy. The supplementally hydrated maternal C. viridis experienced slightly higher rates of CEWL compared with control snakes, but CEWL was primarily driven by ambient temperature and vapor pressure deficit at the time of measurement. At birth, neonate plasma osmolality and CEWL were both directly associated with their mothers' plasma osmolality and CEWL. Additionally, we found that neonate CEWL increased after the first ecdysis, suggesting that natal skin may help neonates avoid desiccation. Investigating and quantifying physiological implications of water shortage and dehydration can help us better understand the effects of drought and predict how wild populations of arid-adapted reptiles may respond to the predicted increase in frequency and severity of droughts.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142818273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From molecular to physiological responses: improved stress tolerance and longevity in Drosophila melanogaster under fluctuating thermal regimes.","authors":"Florence Hunter-Manseau, Jolène Cormier, Nicolas Pichaud","doi":"10.1242/jeb.249402","DOIUrl":"10.1242/jeb.249402","url":null,"abstract":"<p><p>Climate change introduces greater thermal variability, profoundly affecting ectothermic species whose body temperatures rely heavily on the environment. Understanding the physiological and metabolic responses to such variability is crucial for predicting how these species will cope with changing climates. This study investigates how chronic thermal stress impacts mitochondrial metabolism and physiological parameters in Drosophila melanogaster, hypothesizing that a fluctuating thermal regime (FTR) activates protective mechanisms enhancing stress tolerance and longevity. To test this, Drosophila were exposed to constant 24°C or to an FTR of 24°C:15°C (day:night) cycle following an initial 5 day period at 24°C. The FTR group exhibited rapid transcript level changes after the first day of FTR, particularly those related to heat shock proteins, mitophagy and regulatory factors, which returned to initial levels after 5 days. Mitochondrial respiration rates initially decreased after 1 and 2 days of FTR, then recovered by day 5, indicating rapid acclimation. Enhanced antioxidant enzyme activities were observed early in the FTR group, after 1 day for mtSOD and SODcyt+ext and 3 days for both SOD and catalase, followed by a decline by day 5, suggesting efficient oxidative stress management. The FTR group showed lower CTmax on day 3, reflecting possible physiological strain at that time point, and complete recovery by day 5. Longevity increased under FTR, highlighting the activation of protective mechanisms with beneficial long-term effects. These results suggest that FTR prompts a temporal succession of rapid physiological adjustments at different levels of organisation, enhancing long-term survival in D. melanogaster.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142854213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Field respirometry in a wild maternity colony of Bechstein's bats (Myotis bechsteinii) indicates high metabolic costs above but not below the thermoneutral zone.","authors":"Janis M Wolf, Philipp Lehmann, Gerald Kerth","doi":"10.1242/jeb.249975","DOIUrl":"10.1242/jeb.249975","url":null,"abstract":"<p><p>In a warming world, it is crucial to understand how rising temperature affects the physiology of organisms. To investigate the effect of a warming environment on the metabolism of heterothermic bats during the costly lactation period, we characterised metabolic rates in relation to roost temperature, the bats' thermoregulatory state (normothermia or torpor), time of day and age of juveniles. In a field experiment, we heated the communal roosts of a wild colony of Bechstein's bats (Myotis bechsteinii) every other day while measuring metabolic rates using flow-through respirometry. As expected, metabolic rates were lowest when the bats were in torpor. However, when bats were normothermic, colder temperatures had little effect on metabolic rates, which we attribute to the thermoregulatory benefits of digestion-induced thermogenesis and social thermoregulation. In contrast, metabolic rates increased significantly at temperatures above the thermoneutral zone. Contrary to our expectations, metabolic rates were not lower in heated roosts, where temperatures remained close to the bats' thermoneutral zone, than in unheated roosts, where temperatures were more variable. Our results show that torpor and digestion-induced thermogenesis are effective mechanisms that allow bats to energetically buffer cold conditions. The finding that metabolic rates increased significantly at temperatures above the thermoneutral zone suggests that the physiological and behavioural abilities of Bechstein's bats to keep energy costs low at high temperatures are limited. Our study highlights that temperate-zone bats are well adapted to tolerate cold temperatures, but may lack protective mechanisms against heat, which could be a threat in times of global warming.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142877321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}