Journal of Experimental Biology最新文献

{"title":"Effects of diet quality on the musculoskeletal system of the masticatory apparatus in Mus musculus domesticus.","authors":"Levke Hansen, Daniela E Winkler, Anja Guenther, Christine Böhmer","doi":"10.1242/jeb.249735","DOIUrl":"https://doi.org/10.1242/jeb.249735","url":null,"abstract":"<p><p>Isolated environments such as islands can provide restricted dietary resources of varying quality. This has a major impact on evolution of island species, and can lead to rapid morphological adaptation, especially in small mammals. In order to understand the impact of diet quality on the masticatory apparatus in the model species Mus musculus domesticus, we quantitatively analyzed the main masticatory muscles and the mandibular morphology in semi-natural populations kept on different diets for six generations. The investigation of individuals of the F5 generation raised on high quality (HQ) or standard quality (SQ) diets revealed significantly higher muscle mass and larger anatomical cross-sectional area (ACSA) of the M. masseter and the M. temporalis in mice raised on SQ diet as compared to HQ diet. A trend towards more robust (i.e., sturdy) mandible morphology in SQ mice as compared to HQ mice was evident. The investigation of individuals of two F6 generations which were fed on a diet different from that of the preceding generation revealed that the diet switch from HQ to SQ resulted in increased muscle size, whereas the diet switch from SQ to HQ lead to decreased muscle size as compared to the respective control group. The mandible displayed limited differences in morphology. These findings suggest that within six generations, diet quality could be a selection factor for morphological traits in the mandible which may become epigenetically fixed. However, additional studies such as DNA methylation and histone modification are necessary to unravel the role of the epigenome in this context.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144008096","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":"Gait compliance alters ground reaction forces in human walking: implications for the evolution of bipedalism.","authors":"Sarah E Little-Letsinger, Rebecca Cook, Demi Wilson, Kennedy Truitt, Daniel Schmitt","doi":"10.1242/jeb.250219","DOIUrl":"https://doi.org/10.1242/jeb.250219","url":null,"abstract":"<p><p>Despite decades of inquiry, the evolution of bipedalism remains a mystery. Some have argued that a compliant walking gait, with deep hip and knee flexion to moderate ground reaction forces, was used by early human ancestors, marking our relatively stiff modern gait as a recently acquired feature of our genus. Building on previous compliant walking studies, we test the hypothesis that vertical ground reaction forces are attenuated in compliant walking through increases in contact time. Twenty-four adults walked on an instrumented runway using a normal and a compliant gait at a self-selected pace. Vertical, mediolateral, and fore-aft ground reaction forces were assessed using both standard discrete and novel continuous methods. We report mixed evidence for the effect of contact time on peak vertical force in the first third of stance during compliant walking. Our data show greater vertical forces at midstance and reduced vertical forces in the last third of stance during compliant walking. Vertical impulse did not differ between gaits. Compliant walking minimized medial and fore-directed forces and increased lateral and aft-directed forces compared to stiff walking. We identified robust increases in lateral and aft impulses. In addition to discrete analysis of force trace peaks, we employed continuous waveform analysis of force traces that confirmed and further illuminated these patterns. Our data clearly demonstrate that compliant walking has lower vertical forces in late stance, with lower medial and fore forces and higher lateral and aft forces across the gait cycle. These results point toward key changes in leg and foot mechanics and advance our understanding of advantages and challenges associated with the evolution of bipedalism.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144012434","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":"Behavioural evidence of a humidistat: a temperature-compensating mechanism of hydroregulation.","authors":"Danilo Giacometti, Glenn J Tattersall","doi":"10.1242/jeb.250297","DOIUrl":"https://doi.org/10.1242/jeb.250297","url":null,"abstract":"<p><p>The ability to control hydration state is essential for terrestrial species, especially amphibians, which are highly susceptible to dehydration. Here, we examined how temperature (17°C vs. 22°C) influenced behavioral hydroregulation in spotted salamanders (Ambystoma maculatum) using a laboratory humidity gradient. Salamanders defended a constant vapour pressure deficit (VPD) between temperatures by targeting higher RH at 22°C than at 17°C, possibly to compensate for increased evaporative demand at warmer temperatures. Individuals selecting higher VPDs experienced greater evaporative water loss (EWL), with larger salamanders losing more water than smaller ones after accounting for temperature. Together, these results highlight a trade-off among body size, humidity preference, and desiccation tolerance. Salamanders also rehydrated faster at 22°C than 17°C, highlighting temperature-dependent water uptake rates. Our finding that salamanders regulated a constant driving force of evaporation between temperatures suggests the ability to detect rates of EWL. Local evaporative cooling of the skin is a plausible mechanism: if moist-skinned ectotherms show local evaporative cooling on exposed surfaces but not on those in contact with the substrate, then the temperature gradient between dorsal and ventral skin could act as an effective cue to detect the drive for EWL. Ultimately, our study underscores the complexity of amphibian hydroregulation and emphasises the role of behaviour in maintaining hydration state.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143968976","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":"Diet-dependent production of calcium- and phosphorus-rich 'spheroids' along the intestine of Burmese pythons: identification of a new cell type?","authors":"Jehan-Hervé Lignot, Robert K Pope, Stephen M Secor","doi":"10.1242/jeb.249620","DOIUrl":"https://doi.org/10.1242/jeb.249620","url":null,"abstract":"<p><p>Burmese pythons, Python molurus bivittatus, digest the skeleton of their prey. It must result in a high amount of calcium and phosphorus passing through the intestinal lining. To determine how Burmese pythons can process this ion influx, the effects of different nutritional diets were examined in juveniles reared in captivity using three different diets: a normal diet with calcium and phosphorus provided from entire rodents; a low-calcium and phosphorus diet using rodents with no bones ('boneless prey'), and a calcium-rich diet composed of boneless rodents supplemented with calcium carbonate (CaCO3) through intraperitoneal injections inside the prey. The effect of these diets was analysed along the intestinal mucosa using light and electron microscopy techniques (alizarin red S and peroxidase staining, EDX analyses). Blood calcium and hormone levels (parathyroid hormone, PTH and calcitonin) were also analysed from fasting pythons and snakes repeatedly fed with either a normal prey or a low calcium and phosphorus diet (boneless rats). Results revealed the presence of specialised cells in the intestinal epithelium that are involved in the production of calcium and phosphorus particles in fed snakes. These cells have an apical crypt possessing a multi-layered particle made of calcium, phosphorus and iron-rich nucleation elements in the centre. In fasting snakes, this cell type has empty crypts. When snakes are fed with a boneless prey, particles are not produced by this cell type, although iron elements are located within the crypts. When calcium supplements are added to a boneless meal, large particles fill the crypts. When snakes are fed repeatedly with a low-calcium diet, blood calcium level drops while levels of calcitonin, and particularly of those of PTH, increase. Therefore, Burmese pythons possess a specialised intestinal cell type involved in excreting excess dissolved calcium and phosphorus that originate from the prey and are precipitated as particles that must accumulate in the faeces. This cell type is also found in other snake species eating vertebrates (some Boidae and a Colubrid) along with a lizard, the Gila monster, Heloderma suspectum. A broader analysis among vertebrates that ingest their prey whole and dissolve the prey skeleton would allow a thorough evolutionary analysis.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143995652","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":"Modelling endurance in free-ranging animals using tracking collars: insights from domestic hunting dogs.","authors":"Pablo Rozier-Delgado, Mathieu Garel, Cyril Rousset, Anne Loison, Baptiste Morel","doi":"10.1242/jeb.250259","DOIUrl":"https://doi.org/10.1242/jeb.250259","url":null,"abstract":"<p><p>Endurance is crucial for animal survival yet remains poorly studied in free-ranging animals. An animal's endurance time decreases as a hyperbolic function of increasing exercise intensity, called the speed-duration relationship. This relationship allows for defining critical speed, the endurance threshold separating efforts where metabolic homeostasis is achievable from efforts where fatigue accumulates drastically. Using tracking collars on domestic dogs during hunting sessions, we demonstrated the ability to determine the speed-duration relationship and its parameters: the theoretical maximal speed (Si), critical speed (Sc), and distance reserve (DACmax). This new method exhibited good repeatability across sessions and bypasses conventional laboratory assessment, allowing the characterisation of physical abilities in natura. Our approach provides the unique possibility to study when, where, and how long free-ranging animals experience fatigue and helps uncover how environmental factors affect their energy expenditure. All codes for applying our analyses are openly available (figshareLink).</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143974272","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 integrative biology of decoy coloration in lizards.","authors":"Charles M Watson, Christian L Cox","doi":"10.1242/jeb.249623","DOIUrl":"https://doi.org/10.1242/jeb.249623","url":null,"abstract":"<p><p>Anti-predator coloration is a widespread phenomenon that includes such tactics as aposematism, crypsis and mimicry. Most research on colorful anti-predator traits has focused on these well-known and well-studied tactics. One anti-predator trait that is found in diverse taxa yet is still poorly understood is anti-predator decoys. New advances in phylogenetics, genomics and molecular biology have allowed for an enriched understanding of the integrative biology of this type of anti-predator trait, particularly in lizards. While anti-predator decoy coloration is present in multiple taxa across the animal tree of life, it is particularly prevalent among lizards, which use both color and behavior to attract predator attention to the tail, which is often autotomizable and can regrow. In this Review, we discuss the integrative biology of decoy coloration in lizards, including the role of color, ontogenetic variation, gene expression and genomics. We begin by reviewing the mechanisms of the production of decoy coloration in lizards then discuss the function and macroevolution of decoy coloration. Finally, we suggest potentially fruitful avenues for future research on anti-predator decoys in lizards and other animal taxa.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":"228 8","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143985529","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":"Effects of actin remodeling inhibitors on cellular energy metabolism of a model marine bivalve, the Pacific oyster.","authors":"Eugene P Sokolov, Inna M Sokolova","doi":"10.1242/jeb.249708","DOIUrl":"https://doi.org/10.1242/jeb.249708","url":null,"abstract":"<p><p>Actin, the most abundant cellular protein, is essential for maintaining structural organization, mechanical stability and cellular motility. The actin cytoskeleton undergoes continuous ATP-dependent reorganization, incurring significant energy costs through treadmilling. However, experimental quantifications of these energy expenditures, especially in ectotherms, remain scarce. In this study, we assessed the energy costs of actin remodeling in the Pacific oyster Crassostrea [also Magallana] gigas, a marine bivalve, by measuring oxygen consumption in the presence of inhibitors of actin treadmilling (latrunculin B, jasplakinolide and cytochalasin D). Our results indicate that under normal physiological conditions, actin remodeling contributes less than 5% to the cellular energy budget in gill and mantle cells of oysters. Unexpectedly, cytochalasin D induced a marked increase in mitochondrial proton leak, observed both in intact cells and isolated mitochondria, suggesting a connection between actin disorganization and increased mitochondrial maintenance costs. Notably, jasplakinolide and latrunculin B, which inhibit actin treadmilling through different mechanisms from those of cytochalasin D, had no effect on mitochondrial respiration. This suggests that different mechanisms of actin cytoskeleton disruption can lead to distinct cellular outcomes. Given the significant role of proton leak in cellular respiration, these findings suggest that actin dynamics may play a crucial role in regulating mitochondrial metabolism, with broad implications for cellular energy costs. Further studies are needed to elucidate the underlying mechanisms of actin-mitochondria interactions and their broader relevance to the regulation of cellular metabolism in ectothermic species.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":"228 8","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12045635/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144012438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How lacertids resolve spatial details: visual acuity in the common wall lizard (Podarcis muralis).","authors":"Anna Kawamoto, Guillem Pérez I de Lanuza, David Vie Giner, Jindřich Brejcha, Enrique Font","doi":"10.1242/jeb.249422","DOIUrl":"https://doi.org/10.1242/jeb.249422","url":null,"abstract":"<p><p>Visual acuity, the ability to discern static spatial details, is crucial for understanding how organisms perceive their environment. Lacertid lizards are diurnal, feed on small prey, and communicate using multiple visual signals, including postures, dynamic displays and conspicuous colour patches. However, their visual acuity remains unstudied, leaving a critical gap in our understanding of their visual capabilities. Visual acuity is often estimated behaviourally using an optomotor apparatus, which quantifies a reflex-orienting movement called the optomotor response (OMR), or histologically by evaluating retinal ganglion cell (RGC) densities. We combined these two techniques to estimate visual acuity in a lacertid lizard, Podarcis muralis. OMR assays estimated an acuity of 2.05 cpd, while RGC counts revealed a peak density (>7000 cells mm-2) within the area centralis, corresponding to 1.56 cpd. RGC topographic maps revealed additional areas of high cell density in the dorso-nasal and dorso-temporal regions, while the area centralis was located slightly ventrally in the centro-temporal retina. This RGC distribution suggests adaptations to resolve stimuli in the centre and lower parts of the lizard's visual field, which may enhance predator and prey detection on the ground. Using our estimated acuities, we calculated that a lizard can detect a conspecific from 10 m and a 2 mm-long object from 40 cm away. In addition, we generated AcuityView images (R package) showing how this species might discern conspecific colour patches at different distances. These images suggest that beyond 10 cm, the surroundings become increasingly blurred, suggesting a role for static visual signals specifically in close-range communication.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":"228 8","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143995608","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":"Comparative mechanical and elastic properties of the dorsal and ventral tendons in the peduncle of harbor porpoise (Phocoena phocoena).","authors":"Alexa R Cesari, Jesse K Placone, Nicole L Ramo, Michael V Rosario, Matthew Morris, Danielle S Adams, Frank E Fish","doi":"10.1242/jeb.249621","DOIUrl":"10.1242/jeb.249621","url":null,"abstract":"<p><p>Cetaceans swim via vertical movements of the tail. The tendons located in the caudal peduncle are attached to the caudal vertebrae to generate propulsive oscillations. Arguments have centered on whether the upstrokes and downstrokes of the tail and propulsive flukes are symmetrical or asymmetrical in time. Previous research from kinematics of swimming animals, muscle architecture and histology has supported both conditions. However, the composition and structure of the tendons suggest a potential mechanism to evaluate this disparity. In this study, the tendons of the caudal peduncle of the harbor porpoise (Phocoena phocoena) - specifically, the extensor caudae medialis (ECM) and the extensor caudae lateralis (ECL) from the epaxial muscle, and the medial hypaxialis lumborum (MHL) from the hypaxial muscle - were mechanically tested. Ramp to failure was performed on isolated tendon fascicles. Stress relaxation tests to 3% strain were also performed on fascicles. Polarized light microscopy was used to visualize the fibril crimp as tensile forces were applied to fascicles. Uncrimping of isolated fascicles was visualized at mean strain values between 0.031% and 0.048%. The maximum elastic moduli of fascicles taken to failure were between 1039.5 and 1185.8 MPa. No differences were found in the mechanical performance of the fascicles of the epaxial and hypaxial tendons. The mechanical properties of peduncle fascicles suggest a symmetrical stroke cycle for swimming by the porpoise.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663557","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":"Freeze-tolerant crickets fortify their actin cytoskeleton in fat body tissue.","authors":"Maranda L van Oirschot, Jantina Toxopeus","doi":"10.1242/jeb.249947","DOIUrl":"10.1242/jeb.249947","url":null,"abstract":"<p><p>Animals that overwinter in temperate climates must prevent or repair damage to their cells to survive winter, but we know little about how they protect cellular structure at the cytoskeletal level. Both chilling (no ice formation) and freezing (ice formation) are hypothesized to cause substantial challenges to cell structure and the cytoskeleton. The spring field cricket Gryllus veletis becomes freeze tolerant following a 6 week acclimation to autumn-like conditions, during which they differentially express multiple cytoskeleton-related genes. We tested the hypothesis that G. veletis alter their cytoskeleton during acclimation to support maintenance of cytoskeletal structure during freezing and thawing. We used immunocytochemistry and confocal microscopy to characterize changes in microfilaments (F-actin, a polymer of G-actin) and microtubules (a polymer of α- and β-tubulin) in three tissues. While we saw no effect of acclimation on microtubules, crickets increased the abundance of microfilaments in fat body tissue and Malpighian tubules. When we chilled or froze these freeze-tolerant crickets, there was no apparent damage to the actin or tubulin cytoskeleton in fat body tissue, but there was decreased cytoskeleton abundance in Malpighian tubules. When we froze freeze-intolerant (unacclimated) crickets, microfilament abundance decreased in fat body tissue, while microfilaments were unaffected by chilling to the same subzero temperature. Our study shows that freeze-tolerant crickets are able to prevent or rapidly repair ice-induced damage to the actin cytoskeleton in fat body tissue, likely as a result of preparatory changes in advance of freezing, i.e. during acclimation. We suggest future directions examining the mechanisms that underlie these structural changes.</p>","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143624712","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}