Wiley: Journal of Experimental Zoology Part A: Ecological and Integrative Physiology: Table of Contents

Behavioral Evidence for a Chemical Disturbance Cue in Bat Rays (Myliobatis californica)

Wed, 10 Jun 2026 21:42:30 -0700

Chased Bat rays may release chemical cues that alert conspecifics of predator threats. In our experiment, Receiver rays exposed to water from a chased “Sender” ray increased swimming speed and shifted to more active behavioral states.

ABSTRACT

The release of waterborne chemical cues is a well-documented anti-predator strategy in teleost fish, allowing individuals to detect, and respond to, predation threats. However, little is known about whether an ancient group of fishes, elasmobranchs, employ similar mechanisms to communicate predation risk. Here, we experimentally investigate the behavioral and physiological responses of Bat rays (Myliobatis californica) following the manipulation of an upstream conspecific. Specifically, we examined whether Bat rays receiving water from an upstream conspecific that had been physically chased with a stick for 30 s, simulating a non-injurious predation disturbance, exhibited changes in activity levels and physiological stress markers. Receiving Bat rays increased their velocity by approximately 3 cm/s (~21%) compared to their pre-exposure state, whereas Control rays showed no significant change. Receivers also exhibited a significant shift toward active swimming behaviors, while Controls spent more time in passive behaviors. This shift was positively correlated with velocity, reinforcing that exposure to waterborne disturbance cues from a distressed conspecific triggered increased activity. Physiological measurements showed no significant differences between groups in glucose, β-HB, lactate, or pH levels. We suggest the activity increase corresponds with a flight-type response to predation risk. These findings reveal a previously undocumented communication mechanism in marine predators, contributing to a broader understanding elasmobranch behavior and physiology.

Adaptive Features of the Avian Integument: A Comparative Study of the Laughing Dove, Quail, Muscovy Duck, With Emphasis on the Preen Gland Secretions and Associated Microbial Communities

Wed, 10 Jun 2026 21:36:10 -0700

The histological analysis revealed that the laughing dove exhibited the thinnest skin with frequent observations of Herbst corpuscles and pigmented epidermis, reflecting an aerial mode of life. Conversely, the quail and Muscovy duck exhibited thicker skin, and no pigment cells were observed in the skin, implying a tendency toward a terrestrial mode of life. The microbial load in the Muscovy duck was higher than that observed in the laughing dove and quail, possibly due to frequent water exposure and congregation mode of life. The preen secretions of the laughing dove were more potent in combating microbial invasion and growth than those of the Muscovy duck, indicating a functional shift of the secretions in the duck toward the hydrophobic properties and plumage waterproofing.

ABSTRACT

The current work compared the integumentary architecture and feather microbiomes among three avian species inhabiting different ecological niches: the aerial laughing dove (Spilopelia senegalensis), the terrestrial quail (Coturnix coturnix), and the semi-aquatic Muscovy duck (Cairina moschata). Histological, histochemical, and microbial analyses revealed clear interspecific variations that appear to be associatedwith the distinct lifestyles of the examined species. The laughing dove exhibited the thinnest skin, numerous Herbst corpuscles, and a pigmented epidermis, features related to the aerial mode of life and serving to mitigate the frequent exposure to sunlight. in contrast, the quail showed moderately thick epidermis, non-pigmented skin, and less pronounced dispersal of mechanoreceptors, reflecting its tendency toward the ground-dwelling lifestyle. While the Muscovy duck possessed the thickest skin, characterized by the highest microbial load, which aligns with its semi-aquatic habitat and frequent water contact. Furthermore, the preen secretions of the laughing dove exhibited strong antimicrobial potency, while those of the Muscovy duck were functionally engaged in waterproofing rather than microbial combating. Collectively, these findings highlight how skin architecture and microbial populations modulate in response to the environmental challenges, such as ecological demands and the surrounding microenvironment.

The Impact of Substrate Properties on the Kinematics of Locomotion in a Limb‐Reduced Skink, Ablepharus kitaibelii (Squamata: Scincidae)

Vladislav Vergilov, Anthony Herrel, Patrick Lemell — Wed, 03 Jun 2026 21:45:31 -0700

ABSTRACT

The environment through which animals move is rarely homogenous and requires animals to change their kinematics. Especially for small animals, even seemingly minor variations in substrate characteristics may have strong impacts on their locomotor speed and kinematics. In most quadrupedal animals, obstacles are avoided by adapting the movements of the limbs and body, allowing animals to effectively negotiate a diversity of terrains. However, how limb-reduced animals change their kinematics in function of variation in locomotor substrates remains poorly known. Here we study the limb-reduced skink Ablepharus kitaibelii moving on two different substrates (sand and bitumen) across a range of speeds. Our results show an effect of speed as well as significant differences between substrates in most spatio-temporal gait parameters studied. Moreover, speed modulation differed between the two substrates, suggesting that the kinematic and motor control strategies used by this species are substrate-dependent. Axial movements were strong determinants of overall locomotor speed in A. kitaibelii, suggesting that in limb-reduced species, the axial system drives variation in locomotor speed. Our data provide a baseline for future studies on other limb-reduced and non-limb-reduced species.

Effects of Summer Heat Stress on Physiological Parameters and Reproductive Efficiency of Barbarine Ewes Under Natural Outdoor or Indoor Conditions

Samia Khnissi, Dorra Aouadi, Hela Chalouati, Mourad Rekik, Imène Ben Salem — Tue, 02 Jun 2026 23:31:29 -0700

ABSTRACT

Climate change and rising ambient temperatures increasingly challenge sheep production systems in arid and semi-arid regions, particularly during the summer breeding season. This study evaluated the effects of heat stress and direct solar exposure on physiological responses, metabolic profile, and reproductive performance of Barbarine ewes, a fat-tailed breed adapted to harsh environments. A total of 112 non-lactating multiparous ewes were allocated to two groups during summer mating: an indoor group protected from solar radiation (IDGp; n = 58) and an outdoor group exposed to direct sunlight (ODGp; n = 54). Both groups experienced severe to extreme heat stress for more than 65% of the experimental period. Sun exposure significantly increased rectal temperature (+0.2 to +0.6°C), respiratory rate (up to 130 vs 61 breaths/min), and heart rate (up to 95 vs 87 beats/min) in outdoor ewes (ODGp) compared to indoor ewes (IDGp), indicating a higher physiological heat load in sun-exposed animals. The temperature–humidity index (THI) remained comparable between groups (≈24.7), suggesting comparable THI values. Metabolic responses were characterized by increased plasma concentrations of triglycerides (+36%), total proteins (+7.5%), urea (+13%), creatinine (+34%), and potassium (+5%), along with a decrease in cholesterol levels (−15%) in ODGp compared to IDGp. Despite these physiological and metabolic adjustments, body condition score and live weight were maintained in both groups. Reproductive performance was not affected by solar exposure, with estrus occurrence exceeding 94%, an ovulation rate of 1.17, and no significant differences in fertility (79.3% vs 77.8%), prolificacy, or fecundity between groups. These findings indicate that, although direct solar radiation increases physiological strain, it does not impair reproductive function under comparable ambient thermal conditions. Barbarine ewes thus exhibit strong functional resilience to heat stress, highlighting their suitability for extensive production systems in hot and dry environments.

Prolactin and Triiodothyronine Modulate Seasonal Variation in Brown Adipose Tissue in Djungarian Hamsters

Mon, 01 Jun 2026 21:21:03 -0700

ABSTRACT

Seasonal photoperiodic cycles regulate energy rheostasis in many animals. Brown adipose tissue (BAT) and the liver are key metabolic organs that show remarkable plasticity in response to photoperiodic conditions. Prolactin (PRL) and thyroid hormones are endocrine signals that transmit neural-derived photoperiodic time measurement encoding to regulate peripheral tissues. Using Djungarian hamsters (Phodopus sungorus), a well-established seasonal model, we examined the effects of photoperiod, triiodothyronine (T3), and PRL on liver and brown adipose tissue morphology and lipid content. Tissue mass, brown adipose tissue somatic index, and histological lipid content were quantified in three experiments that investigated tissue variation (1) across photoinduced seasonal cycles, and the sufficiency of acute (2) triiodothyronine, and (3) prolactin administration. Long photoperiod (LP) exposure maintained large BAT and higher lipid content, whereas short photoperiod (SP) exposure reduced BAT mass and lipid content. T3 treatment increased the BAT mass but did not impact lipid content. Conversely, PRL treatment increased BAT lipid content but did not impact tissue mass. Together, these findings identify triiodothyronine and prolactin as critical regulators of metabolic tissues.

Disentangling Temporal and Environmental Effects on Hematological Values in Prairie Rattlesnakes (Crotalus viridis)

Thu, 28 May 2026 21:15:22 -0700

ABSTRACT

Hematologic assessment is a common clinical tool used to characterize both individual and population health. In ectothermic organisms, the hematologic response is influenced by external factors such as temperature and season, especially in temperate species. Yet, specific environmental effects have received little direct attention. Therefore, to improve the diagnostic utility of hematologic assessments in reptiles, it is imperative to characterize physiological variation in diagnostic parameters. Our objective was to determine the impacts of temperature and season on commonly assessed components of the complete blood count, including packed cell volume (PCV), total solids (TS) and white blood cell count (WBC). We used a group of 17 long-term captive Prairie Rattlesnakes (Crotalus viridis). Animals were randomly assigned to either a control group kept in an environmental chamber at a constant temperature of 25°C or an experimental group housed in an environmental chamber which reflected average ambient temperature throughout the year (5°C–32°C). We collected blood samples twice monthly for 13 months. We found WBC decreased as the mean previous 14-day temperature increased, with no effect of season. Changes in total WBC were driven by increased numbers of lymphocytes and decreased number of heterophils and azurophils at higher temperatures. We found a difference in the effect of time since the start of the experiment between control and experimental groups in PCV, with no change in our control group, but a decrease in our experimental group through time. Total solids were higher in the control group, but there was no direct effect of temperature or season. Therefore, we conclude environmental conditions, rather than season, drive variation in hematologic parameters of otherwise healthy snakes and should be included in the interpretation of hematologic assessments in wild reptiles.

Seasonal Thermal Ecology and Locomotor Performance of an Andean Viviparous Lizard: Assessment of Its Vulnerability to Climate Change

Mon, 18 May 2026 22:24:05 -0700

ABSTRACT

Lizards, in general, tend to maintain body temperatures close to and often below physiological optima because of variations in body temperatures, as well as the asymmetry of thermal performance curves. Thermal ecophysiology has been studied in several species of the genus Phymaturus; however, Phymaturus cf. palluma is a taxon that has not yet been formally described. We evaluated key thermal ecophysiological traits of this taxon during two seasons, summer and autumn, in a high-altitude desert in the Precordillera of central-western Argentina. Seasonally, we compare thermal parameters, while during the summer, we evaluate locomotor performance traits and estimate vulnerability to global warming. In the field, we recorded body, microenvironmental, and operative temperatures. In the laboratory, we measured preferred temperatures, calculated the thermoregulatory efficiency index, and estimated the thermal sensitivity of locomotion (short and long runs) at five different body temperatures to assess its vulnerability to global warming. Significant seasonal differences were observed in preferred and body temperature in the field, but not in microenvironmental temperatures, while the preferred temperature was higher than the body temperature in both seasons, and the thermoregulatory efficiency was moderate (E = 0.68). The optimum temperature was lower than the preferred temperature, indicating a lack of support for the thermal coadaptation hypothesis. We conclude that this taxon is a eurythermic lizard and a moderate thermoregulator, with thermal sensitivity in its locomotor performance. Vulnerability indices to global warming suggest that P. cf. palluma has the ecophysiological capacity to adapt to changes in its natural environment.

Ionic Regulation in Estuarine and Freshwater Palaemonid Shrimp

Gabriela E. Musin, Silvina A. Pinoni, Romina B. Ituarte — Sun, 17 May 2026 21:01:26 -0700

ABSTRACT

Hyper-regulation requires animals to absorb ions against concentration gradients. Although ion absorption would involve different pathways in estuarine and freshwater organisms, current models remain incomplete for euryhaline palaemonid shrimp. This study examines the hyper-regulatory performance of two closely related euryhaline palaemonid species in response to a similar environmental salinity gradient. We measured the function of key branchial ion transport-related enzymes, critical hemolymph parameters, and muscle moisture following 3-week exposure to high and low salinity treatments: 20‰S and 5‰S for the marine/estuarine shrimp Palaemon macrodactylus; 17‰S and 2‰S for the ‘freshwater’ species Palaemon argentinus. Both shrimp species exhibited weak and strong osmoregulatory capacities against high and low salinities, respectively. At a salinity of 5‰S, the estuarine shrimp P. macrodactylus experienced hemolymph sodium and chloride leakage as well as water accumulation in muscle tissue. These parameters remained unchanged in P. argentinus, whereas gill H⁺-ATPase (VHA) activity was 9.4 times higher at the low salinity treatment. An apical VHA secreting protons would facilitate the transepithelial influx of Na⁺ through the gills of the freshwater shrimp. The unexpected increase in total protein concentration may have obscured the levels of specific VHA activity in P. macrodactylus kept at the low salinity. Overall, tissue swelling, ion leakage, and increased protein concentration indicate sublethal effects in P. macrodactylus following long-term exposure to 5‰S. Such physiological dysfunctions could severely impact the survival of the estuarine species in salinities below 5‰S.

Liver X Receptor α (LXRα) Regulates 5β‐Reductase (AKR1D1) Expression in Avian Embryos: Implications for Yolk Steroid Metabolism

Mon, 11 May 2026 21:12:47 -0700

ABSTRACT

Steroid-mediated maternal effects are well-studied as a source of phenotypic variation. In bird eggs, the yolk contains various steroids that can influence embryonic development. However, one complicating factor in understanding how yolk steroids affect development is that the embryo metabolizes yolk steroids to regulate exposure. The 5β-reduction of steroids by the enzyme 5β-reductase (AKR1D1) has been identified as a pathway through which yolk progesterone, testosterone, and corticosterone are all metabolized early in avian development. We set out to characterize the mechanism through which AKR1D1 expression is regulated in chickens (Gallus gallus) during embryonic development. We found a synthetic and endogenous ligand (22R-hydroxycholesterol) for Liver X Receptor α (LXRα) induced AKR1D1 expression in the embryo and extraembryonic membranes on Day 2 of development. These results suggest that endogenous ligands of LXRα induce AKR1D1 expression and regulate the metabolism of yolk steroids during development.

Entomopathogenic Potential of a Species of Serratia marcescens Originating from the Gut of Melon Fly: Isolation, Characterization and Effect of Oral Administration

Yi Li, Lifei Chen, Chongyang Lu, Xun Yu, Wei Li, Xuyuan Gao — Mon, 11 May 2026 21:12:47 -0700

ABSTRACT

The melon fly, Bactrocera cucurbitae (Coquillett), represents a devastating agricultural pest species. Conventional chemical control strategies are increasingly compromised by the development of insecticide resistance. Given the pivotal role of the gut microbiota in insect physiology and host fitness, it is necessary to isolate gut-derived bacterial strains from adult melon flies and assess their insecticidal efficacy against adult flies. Isolation of culturable gut microbiota from adult melon flies that died of natural causes yielded 122 bacterial strains. Among the 10 virulent bacterial isolates, Serratia marcescens strain SMLY-1 was identified as a highly pathogenic strain against adult melon flies. In addition, oral administration of SMLY-1 significantly reduced survival rates of adult melon flies in a dose-dependent manner. Histopathological analysis suggested that SMLY-1 administration resulted in progressive midgut damage, which was manifested by epithelial cell desquamation and vacuolization. Moreover, the gut microbiota homeostasis was disrupted, and microbial richness was reduced. Notably, the genus-level Wilcoxon signed-rank test showed a significant increase in Serratia spp. abundance in the SMLY-1 treatment group compared to the control group, indicating abnormal proliferation of Serratia spp. in intestines. Enzymatic assays showed that key digestive enzymes (AMS, LPS, trypsin) and detoxification enzymes (CarE, GST) activities were significantly reduced as well as antioxidant enzymes exhibited significant alterations. qRT-PCR results suggested that immune-related genes in adult melon flies including Attacin, JNK, and PPO were sustained upregulated whereas Cecropin, PGRP, IMD and GST were significantly downregulated. These findings establish SMLY-1 as a promising candidate for the biocontrol of melon flies in the future.

Growth Hormone Association With Testicular Recrudescence in a Free‐Living Passerine, Amandava amandava

Banalata Mohanty — Mon, 11 May 2026 21:12:47 -0700

ABSTRACT

Emerging evidence confirms the expression of functional growth hormone (GH) receptors in the male and female reproductive systems, and suggests that the GH signaling might influence gonadal function by acting at different levels of the hypothalamic-pituitary-gonadal (HPG) axis in animals and mammals. Despite this, the role of GH in the modulation of the gonadal cycle in seasonal breeders has been less explored. This study focused on a free-living passerine, Amandava amandava (Red Munia), a distinct seasonal breeder. It aimed at elucidating the plasticity in pituitary expression of the GH, and alteration in the plasma hormone profile across life-history stages parallel to the testicular cycle (histomorphometry and plasma levels of testosterone). The pituitary expression and plasma GH levels remained elevated during the breeding cycle, where the energy-demanding process of testicular recrudescence occurs. The study correlated the plasma GH level with various parameters of the testis and suggests that physiological GH, in association with pituitary gonadotropins, may facilitate the growth and functionality of the testis. The extrapituitary localization of GH in the hypothalamus, optic chiasma, and cerebral cortex during the breeding cycle suggests its paracrine role in the modulation of the gonadotropin-releasing hormone secretion. GH may help meet energy requirements and achieve reproductive status during the transition from the non-breeding to breeding life-history stage, interacting with hormones from other endocrine axes related to reproduction.

Experimental Assessment of the Effects of Substrate Choice on the Duration of Chemical Signals in Fecal Scent‐Marks of Free‐Ranging Iberian Wolves

Elisa Espartosa, Jose Martin, Isabel Barja — Mon, 11 May 2026 21:12:47 -0700

ABSTRACT

Chemical communication, typically based on feces, urine, and glandular secretions, often deposited as substrate scent marks, plays a key role in social organization and communication among many mammals, especially carnivores. This study assesses experimentally whether the type of substrate chosen for fecal deposition and the temperature reached by these substrates influence the persistence of volatile compounds in feces of the Iberian wolf (Canis lupus signatus), considering their role in chemical communication. Fresh fecal scats collected in the wild were divided into equal fragments and positioned in an experimental setup on four different types of substrates exposed to the natural environment. Thereafter, we collected small fecal samples from each fragment at seven different time intervals since the initial deposition and analyzed their lipophilic chemical composition using gas chromatography–mass spectrometry (GC–MS). Variations in the temperature of each substrate were also monitored. The number of compounds in feces decreased with time since deposition and depended on the types of substrates. However, substrate temperature only influenced the persistence of some chemical compounds. These results suggest that when wolves select a substrate to deposit feces, enhancing visual cues (i.e., the different visual conspicuity of feces in different substrates) may play a more important role in fecal marking than trying to increase the persistence of the chemical signal. Overall, our study may help to enhance the understanding of fecal marking behavior in the Iberian wolf, especially regarding the interplay between visual and chemical signaling.

The Effects of Short‐Term Cold Exposure on Serum Lipids, Antioxidant Capacity, and Hepatic Cell Apoptosis in Chinese Moccasin (Deinagkistrodon acutus)

Mon, 11 May 2026 21:12:47 -0700

ABSTRACT

Hibernation is an amazing survival skill that some animals use to cope with natural challenges, and cold is the main stimulus. While most hibernation studies focus on long-term cold adaptation mechanisms, the rapid physiological adjustments triggered by short-term cold exposure may also be key components in the initiation of hibernation. This study focused on 20 Chinese Moccasin (Deinagkistrodon acutus), divided into two groups: an active group (n = 10) and a short-term cold exposure group (n = 10). Using serum biochemistry, serum antioxidant measurements, and liver transcriptome technology, the study explored the effects of short-term cold exposure on snake serum lipids, antioxidant capacity, and apoptosis. The results showed that the levels of cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were significantly lower in cold exposure snakes compared to the active group, whereas total bile acid was higher in the cold exposure group; serum antioxidant indicators glutathione peroxidase, superoxide dismutase, and total antioxidant capacity were lower in cold exposure snakes than in active snakes, whereas the concentration of malondialdehyde was higher in cold exposure snakes. The liver transcriptome revealed that more pro-apoptotic genes were upregulated in active snakes, whereas there were more upregulated anti-apoptotic genes in cold exposure snakes, and the ratio of anti-apoptotic to pro-apoptotic genes was significantly higher in cold exposure snakes than in active snakes. This study not only elucidates the physiological effects of short-term cold exposure on snakes but also advances our understanding of the adaptive mechanisms underlying the transition from activity to hibernation in ectothermic animals.

Automated Profiling of Social Behaviors to Assess the Genetic Basis of Evolution of Aggressive Behaviors in Astyanax mexicanus

Mon, 11 May 2026 21:12:47 -0700

ABSTRACT

Across the animal kingdom, social behaviors such as aggression are critical for survival and reproductive success. While there is significant variation in social behaviors within and between species, the genetic mechanisms underlying natural variation in social behaviors are poorly understood. A central challenge to investigating the mechanisms contributing to the evolution of social behaviors is that these behaviors are typically complex, making them a challenge to quantify. The Mexican tetra, Astyanax mexicanus, is a powerful model for investigating the evolution of traits, as it is a single species that exists as populations of eyed, river-dwelling surface fish and blind cave-dwelling fish. The blind cavefish have evolved morphological and behavioral differences compared to surface fish, including reduced aggression. Here, we developed and validated an automated machine learning pipeline that integrates computerized tracking and supervised behavioral classification to track and quantify aggression-associated behaviors—striking, following, and circling. Using this pipeline, we established that these behaviors are quantitatively different between surface and cave fish during juvenile stages in A. mexicanus, similar to what was observed previously in adults. Moreover, assessment of these aggressive behaviors in surface-cave F2 hybrid fish revealed that striking and following are strongly positively correlated, while striking and circling are negatively correlated, suggesting that these behaviors evolved through some shared genetic mechanisms. These findings demonstrate the power of automated tracking and behavioral phenotyping in multiple fish in A. mexicanus and establish a foundation for future studies investigating the genetic basis of evolution of social behaviors.

Evaluating the Air Respiratory Capacity of Awaous (Chonophorus) tajasica (Gobiiformes: Oxudercidae): A Morpho‐Functional Study

João Pedro Trevisan, Diego Venturelli, Wilfried Klein, André Luis da Cruz — Mon, 11 May 2026 21:12:47 -0700

We demonstrated that Awaous tajasica performs facultative air breathing under experimental conditions of dissolved oxygen limitation, retaining air bubbles in the buccal cavity during gill ventilation. Morpho-functional evidence indicates the use of atmospheric oxygen as a respiratory support under conditions of low water oxygenation.

ABSTRACT

Surface air-gulping behavior has been reported in several gobiid fishes, but its contribution to oxygen uptake remains unclear. This study aimed to evaluate the air-breathing capacity of Awaous tajasica through behavioral observations, measurement of oxygen consumption, and analysis of the functional morphology of its palate and gills. Behavioral observations demonstrated that under hypoxic conditions, the fish moved to the water surface to engulf air bubbles, which remained within the buccal cavity during aquatic gill ventilation before being expelled through an opercular cavity. Oxygen consumption analysis revealed that A. tajasica obtained approximately 70% of its oxygen from the water and 30% from atmospheric air when under low aquatic oxygen conditions. Palate morphology did not reveal specialized respiratory structures, and only typical sensory structures such as taste buds were observed, indicating the absence of a dedicated aerial exchange surface. The retention of an air bubble in the buccal cavity during low aquatic oxygen concentration supports a functional contribution of air gulping to oxygen uptake in A. tajasica, demonstrating aerial oxygen acquisition without specialized air breathing organs in this gobiid species.

Issue Information

Mon, 11 May 2026 21:12:47 -0700

Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, Volume 345, Issue 5, Page 441-443, June 2026.

Impacts of Acute Hypothermia Stress on Gastrointestinal Digestive Enzyme Function and Pathological Changes in Yellowfin Tuna (Thunnus albacares)

Songyuan Liu, Zhengyi Fu, Zhenhua Ma — Sun, 10 May 2026 22:04:13 -0700

ABSTRACT

This study investigated the effects of acute cold stress on digestive function and gastrointestinal pathology in juvenile yellowfin tuna (Thunnus albacares). The experimental setup encompassed a control group (CG, 30°C), a low-temperature group (HT, 24°C), and an ultra-low-temperature group (LT, 18°C), with sampling conducted at 0, 12, 24, and 36 h, respectively, over a total experimental duration of 36 h. We analyzed digestive enzyme activities in the gastric tissue and intestine, expression of key digestive genes, and gastrointestinal histopathology. Results showed that low-temperature stress significantly altered digestive enzyme activities. During the early stage of acute cold exposure (12–24 h), intestinal amylase and trypsin showed enzyme-specific changes, indicating an energy-saving response. With continued exposure over the 36-h experimental period, lipase activity increased substantially in the LT group, suggesting a metabolic shift toward lipid mobilization for energy and membrane fluidity maintenance. Pepsin activity was highest in the HT group and fluctuated in the LT group, reflecting complex gastric microenvironment disruption. Gene expression analysis revealed transcriptional-physiological decoupling. Histopathological findings showed cellular edema, necrosis, and mucous cell hyperplasia in both HT and LT groups, worsening with colder temperatures and longer exposure. By 36 h, the LT group exhibited severe mucosal detachment and glandular structure disruption. In summary, juvenile yellowfin tuna responded to acute cold stress through a biphasic metabolic strategy—initial inhibition followed by compensation—and dynamic gene-enzyme decoupling. While short-term stress activated metabolic plasticity, severe acute cold exposure caused significant gastric tissue damage and digestive dysfunction. These findings provide new insights into thermal adaptation mechanisms and support improved temperature management in aquaculture.

Thirty Weeks of Microplastics Exposure Alters Muscle Quality in Grass Carp (Ctenopharyngodon idella) Revealed by Transcriptomics and Metabolomics

Sun, 10 May 2026 22:02:39 -0700

ABSTRACT

Microplastics (MPs) are tiny particles with a diameter of less than 5 mm generated from the breakdown of plastic waste. In recent years, MPs have extensively entered aquatic environments and accumulated in fish tissues, including the intestine, liver, kidney, and muscle. Previous studies have demonstrated that MP exposure can damage fish organs such as the gastrointestinal tract, gills, and liver, and may pose potential health risks to humans through the food chain. However, the toxicological effects of long-term MP exposure on the muscle tissue of grass carp (Ctenopharyngodon idella), an important edible fish species, remain poorly understood. In this study, we employed an integrated transcriptomic and metabolomic approach to investigate the molecular pathways and metabolic processes in grass carp muscle under 30-week long-term MP exposure. At the transcriptomic level, a total of 1549 genes were upregulated, whereas 1777 genes were downregulated. Gene Ontology (GO) enrichment analysis revealed that 66.6% of differentially expressed genes (DEGs) were assigned to cellular components (CC), with the extracellular space and extracellular region being the most significantly enriched terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that ECM-receptor interaction, focal adhesion, and PI3K-Akt signaling pathways were significantly affected. At the metabolomic level, 118 metabolites were significantly upregulated, whereas 132 metabolites were significantly downregulated, with heterocyclic compounds, alcohols, and amines being notably decreased. KEGG enrichment analysis revealed that these differential metabolites were primarily involved in ABC transporters, sphingolipid metabolism, and d-amino acid metabolism pathways. Integrated analysis suggested that long-term MP exposure induces ECM remodeling and membrane lipid metabolism abnormalities by modulating ECM-related genes and signaling pathways, and may compromise fish muscle quality through mechanisms involving oxidative stress and inflammatory responses. Overall, this study provides novel evidence for the toxicological effects and molecular mechanisms underlying long-term MP exposure and offers important insights for sustainable aquaculture practices and food safety risk assessment.

Beyond Genes: Metabolomic Evidence Indicates Potential Species‐Level Differentiation in European Wild Rabbits

Sun, 10 May 2026 22:01:38 -0700

ABSTRACT

The European rabbit (Oryctolagus cuniculus) plays a key ecological role in Mediterranean ecosystems, yet its populations are declining. Two subspecies, O. c. algirus and O. c. cuniculus, are present in the Iberian Peninsula and exhibit genetic, phenotypic, and ecological differences. The aim of this study was to investigate whether genetic differences between subspecies are reflected in the plasma metabolome of the European rabbit and to identify potential biomarkers for subspecies classification. Comprehensive untargeted metabolomics analyses (n = 49 wild individuals) were performed. Significant and consistent differences in the metabolomic profiles were found between subspecies. Statistically significant differences were detected in nine metabolites; three showed strong discriminatory potential, with Medicagenic acid, MG(P-18:0/0:0/0:0), and Androsta-1,4-diene-17-carboxylicacid, 17-[(ethoxycarbonyl)oxy]-11-hydroxy-3-oxo-, fluoromethyl ester showing strong potential as biomarkers. These findings demonstrate functional divergence between the subspecies, likely related to diet and ecological adaptations. They provide new molecular evidence of metabolic differentiation between subspecies, which may be relevant for understanding evolutionary divergence and could inform conservation strategies.

Highly Divergent Age‐Specific Postembryonic Developmental Constraints and Phenotypic Plasticity in Hatchery‐Reared Tropical Cloudy Damselfish, Dascyllus carneus Fischer, 1885

Sun, 10 May 2026 00:00:00 -0700

ABSTRACT

The proper understanding and standardization of animal growth is one of the fundamental problems in developmental biology. This means their morphology, behavior, and feeding habits will change as they develop. In this study, we integrated geometric morphometric analysis with survival modeling to examine stage-specific morphological development and mortality dynamics in the damselfish Dascyllus carneus. Binomial generalized linear modeling demonstrated significant stage-specific differences in survival probability, with mortality peaking during yolksac, preflexion, and flexion stages; periods characterized by maximum morphometric change and functional transition. Landmark-based analyses revealed significant, directional shape transformations associated with cranial development, trunk deepening, and caudal peduncle differentiation, reflecting functional maturation of feeding and locomotor systems. Shape variability was highest during early developmental stages and declined toward the juvenile stage, indicating progressive morphological stabilization. These findings demonstrate that survival is closely linked to morpho-functional development rather than size alone. Identification of critical developmental stages provides a mechanistic basis for understanding early life survival and offers practical guidance for improving larval rearing and management of ornamental reef fishes.

Seasonal Modulation of Splenic Immune Architecture and Proliferative Activity in the Dromedary Camel (Camelus dromedarius): An Ecological Perspective

Nora A. Taher, Marwa M. Hussein, Enas A. AbdElhafez, Doaa M. Mokhtar — Tue, 05 May 2026 21:33:58 -0700

ABSTRACT

Seasonal environmental fluctuations in desert ecosystems impose significant physiological and immunological challenges on mammals. This study investigated the impact of seasonal variation on the histological organization, immune cell distribution, and proliferative activity of the spleen in adult male dromedary camels (Camelus dromedarius). Spleen samples were collected during winter and summer and analyzed using histological, semithin, immunohistochemical (CD3, CD20, and Ki-67), and morphometrical approaches. Histological examination revealed that the splenic architecture in both seasons consisted of distinct white and red pulp regions. However, summer samples exhibited increased thickness of the splenic capsule and trabeculae, along with more prominent lymphoid follicles and enhanced lymphocyte density. Semithin analysis confirmed a higher cellular density within the germinal centers during summer. Notably, specialized vascular structures, including throttle arteries and glomus-like bodies, were more frequently observed in the red pulp during summer. Immunohistochemically, CD3-positive T lymphocytes were predominantly localized in the periarteriolar lymphoid sheath, with a significant increase in their proportion during summer. CD20-positive B lymphocytes were extensively distributed within the white pulp in both seasons, with significant increased cellular density during summer. Ki-67 immunoreactivity demonstrated increased proliferative activity during summer, particularly within germinal centers. These findings demonstrate that the camel spleen exhibits marked seasonal plasticity, characterized by coordinated changes in immune cell distribution, proliferative activity, and vascular specialization. Such adaptations likely contribute to maintaining immune competence under the extreme environmental conditions of desert habitats.

Tracking the Pulse of the Dunes: Seasonal Metabolic Responses of Liolaemus arambarensis to Climatic Variability

Mon, 27 Apr 2026 00:04:27 -0700

ABSTRACT

Seasonal environmental fluctuations profoundly influence ectothermic vertebrates, regulating their physiology, metabolism, and life cycles. This study investigated the metabolic and morphometric seasonal dynamics of the subtropical sand lizard Liolaemus arambarensis, an endangered species endemic to the coastal dunes of southern Brazil. Over two annual cycles (July 2020 to May 2022), 133 individuals (43 males, 45 females, 45 juveniles) were sampled across all seasons. Through an ecophysiological and biochemical approach, we quantified intermediate metabolism biomarkers—including glucose, proteins, albumin, uric acid, lactate, triglycerides, cholesterol, glycogen, and total lipids—in plasma, liver, gonads, and skeletal muscles, alongside somatic and organ indices. Data were analyzed using generalized linear models (GLMs) with gamma distribution and log-link, followed by type III ANOVA and Tukey post hoc tests. Marked sex- and age-specific seasonal patterns were detected. Females exhibited strong reproductive investment in spring and summer, characterized by increased gonadal proteins and triglycerides, elevated plasma albumin and cholesterol, and depletion of hepatic and muscular reserves—consistent with vitellogenesis and egg production. Males initiated reproductive investment earlier, accumulating hepatic and muscular glycogen and lipids in autumn–winter and mobilizing these reserves during spring for spermatogenesis and reproductive behaviors. Juveniles displayed strategies oriented toward somatic growth and survival, with high tissue lipid content in summer (yolk-derived reserves), hyperglycemia and hepatic glycogen accumulation in winter (suggesting cryoprotective or osmotic roles), and metabolic depletion in autumn, likely due to intraspecific competition for limited resources. The results reveal a plastic physiological strategy combining temperate-like energy conservation during cold periods with tropical-like reproductive allocation in warm months. Such metabolic flexibility underlies the species' adaptation to subtropical thermal variability and provides valuable predictive indicators for ecological modeling and conservation planning in the context of ongoing climate change.

Immune Activation Reshapes Male Reproductive Investment and Induces Intergenerational Effects on Offspring

Francesca Coll, Jose C. Noguera — Mon, 20 Apr 2026 21:50:38 -0700

ABSTRACT

The activation of the immune system is a major physiological challenge that can compromise reproductive investment in males. While its effects on visual sexual signals have been widely investigated, much less is known about how immune activation influences acoustic signaling and other key reproductive traits. In this context, traits such as sperm production and sperm oxidative status (i.e., the balance between antioxidant and pro-oxidant molecules that ultimately determines the level of damage accumulation) are especially relevant, as they may potentially affect not only male fertility but also offspring development and behavior. Here, by experimentally activating the immune system of male field crickets (Gryllus bimaculatus) with a nylon monofilament (i.e., a non-pathogenic immune elicitor), we show that our immune treatment decreased male investment in acoustic sexual signaling, but had no effects on sperm production or sperm oxidative status (i.e., antioxidants and protein oxidative damage levels). However, the eggs fertilized by immune-challenged males showed higher hatching success than those of control (immune-unchallenged) males. Moreover, after hatching, the nymphs sired by immune-challenged males exhibited altered behavioral development, displaying increased locomotor activity and exploratory behavior. These findings suggest that immune activation does not impose uniform costs across pre- and post-copulatory sexually selected traits. Instead, they suggest that when facing an immune challenge, males may strategically prioritize fertility success over sexual attractiveness and mate attraction. Importantly, our results reveal that such shifts extend beyond the male's own reproductive investment to influence offspring behavioral phenotypes, highlighting a previously underappreciated pathway linking immunity to intergenerational behavioral variation.

Synergistic Impacts of Co‐Exposure to Microplastics and Vibrio harveyi on the Immune and Stress Responses of the Big‐Belly Seahorse Hippocampus abdominalis

Jin A Kim, Min‐Min Jung, Seong Don Hwang, Jun‐Hwan Kim, Cheol Young Choi — Sun, 12 Apr 2026 21:21:37 -0700

Synergistic effects of microplastic and Vibrio harveyi co-exposure on big-belly seahorse (Hippocampus abdominalis). Seahorses were exposed to microplastics (50 beads/L of 0.2 μm SMP and 1.0 μm LMP) and injected with V. harveyi (1 × 10³ CFU/mL).

ABSTRACT

Microplastics (MPs) originating from synthetic polymers can act as vectors for harmful microorganisms and pollutants, exacerbating ecological risks. Vibrio harveyi, commonly found in seawater, is a major opportunistic pathogen causing vibriosis in marine fish. MPs and pathogenic bacteria such as V. harveyi have increasingly been recognized as co-contaminants in marine environments. This study investigated the physiological responses of the big-belly seahorse Hippocampus abdominalis exposed to MPs and V. harveyi, both individually and in combination. Seahorses were exposed to small (0.2 μm) and large (1.0 μm) polystyrene MPs (50 beads/L) and V. harveyi (1 × 10³ CFU/mL) for 4 days under controlled conditions. Biochemical parameters and molecular analyses were conducted to assess hepatic function, immune regulation, oxidative stress, and apoptosis-related responses. MP exposure promoted V. harveyi proliferation within seahorse tissues, with higher bacterial copy numbers in the kidney than in the liver, indicating the kidney's active immune role. Plasma biochemical indices (alanine aminotransferase, aspartate aminotransferase, and glucose) and immune-related genes, including lysozyme G, interferon regulatory factor 8, and interleukin 10, were significantly elevated in co-exposure groups compared with individual exposures. Expression of heat shock protein 75 and caspase 8 was also upregulated, suggesting enhanced oxidative stress and activation of apoptotic pathways. These findings indicate that MPs and V. harveyi exert synergistic physiological stress, disrupting immune homeostasis and promoting apoptosis in seahorses. This study provides mechanistic insights into combined MP-pathogen toxicity and establishes the big-belly seahorse as a sensitive bioindicator for complex marine pollution.

Ovulating Female of Nine‐Spined Sticklebacks (Pungitius sinensis) Are Attracted to Substances Derived From Male Kidneys

Miki Nagaya, Hidenobu Yambe, Yasunori Koya — Wed, 08 Apr 2026 21:41:32 -0700

ABSTRACT

Male sticklebacks (Gasterosteidae) produce an adhesive protein called “spiggin” in the tubular epithelial cells of their kidneys, which they use to attach plants or plant debris together and build nesting sites. Spiggin is a glycoprotein excreted in urine. A similar substance has been reported in freshwater sculpins (Cottidae), and it is thought that male sculpins that nest under stones use this glycoprotein in their enlarged kidneys to attract females to their nests. Based on the phylogenetic closeness of sticklebacks and sculpins and the physiological similarities in their kidneys, we hypothesized that spiggin may play a role in attracting females to nesting sites in sticklebacks. We tested this hypothesis using a Y-maze with the nine-spined stickleback (Pungitius sinensis), a member of the Gasterosteidae. Ovulated females were more consistently attracted to male kidney extracts than female kidney extracts. The high-molecular-weight fraction (molecular weight > 3000) separated from the male kidney extract using a dialysis membrane had an attractive effect on ovulating females, while the low-molecular-weight fraction (molecular weight < 3000) had a repellent effect. The water in the aquarium containing nests built by males significantly attracted ovulating females. These results suggest that spiggin or an unknown component associated with spiggin functions to attract ovulating females. In sticklebacks, which evolved from territorial breeding to building elaborate nests, it is possible that the substance that attracts females produced in the male kidney has evolved into an adhesive component that solidifies the nest.

Domestication Effects on Immune Response: Comparison of Phytohemagglutinin‐Induced Skin Swelling in Domesticated Bengalese Finch and Its Wild Ancestor, White‐Rumped Munia

Kenta Suzuki, Kazuo Okanoya — Wed, 08 Apr 2026 21:37:38 -0700

Cell-mediated immune responses were compared between the domesticated Bengalese finch (Lonchura striata var. domestica) and its wild ancestor, the white-rumped munia (Lonchura striata), using phytohemagglutinin (PHA)-induced skin swelling. The results showed that the PHA responses were significantly greater in the Bengalese finch than in the white-rumped munia.

ABSTRACT

The domesticated Bengalese finch (Lonchura striata var. domestica) exhibits more complex songs and altered physiological and behavioral traits compared with its wild ancestor, the white-rumped munia (Lonchura striata). Domestication has been suggested to be associated with immune function, and domestication-related physiological and behavioral traits are thought to co-vary with immune traits. Comparing immune responses between the Bengalese finch and the white-rumped munia provides an opportunity to explore phenotypic differences associated with domestication. In this study, we assessed cell-mediated immune responses using phytohemagglutinin (PHA), a lectin that induces local skin swelling. This PHA-induced swelling (PHA response) is a widely used index of T cell-mediated immunity in ecological immunology. Our results showed that the Bengalese finch exhibited a significantly greater PHA response than the white-rumped munia, indicating higher cell-mediated immune activity in the domesticated birds. These findings suggest a possible association between immune function and domestication-related phenotypic changes, including fearfulness, song complexity, and stress responsiveness.

The Effect of Temperature on Trophic Discrimination of Stable Isotopes (13C and 15N) and Biokinetics in Common Carp (Cyprinus carpio, L. 1758)

Wed, 08 Apr 2026 21:35:30 -0700

ABSTRACT

Stable isotope analysis (SIA) provides essential information toward a better understanding of trophic ecology. However, the interpretation of SIA results relies on assumptions about the trophic discrimination factor (TDF), which aims to improve the accuracy but may lead to bias. In aquatic ecosystems, most biota are poikilothermic organisms, thus temperature is one of the most important parameters affecting all biological processes, including the trophic discrimination of stable isotopes. Therefore, we conducted an experiment to establish TDF for freshwater fish under different temperature regimes (15°C, 25°C, and natural ambient pond temperatures from July to September). We used common carp (Cyprinus carpio, L., 1758) as a model organism. In the first phase of the experiment (weeks 1–6), all fish were fed a defined fish feed to establish a baseline isotopic signal for all individuals. In the second phase (weeks 7–18), fish were randomly divided into three temperature groups and were all fed different types of fish feed. Results indicated temperature-dependent TDF, with nitrogen showing higher temperature dependency, where highest TDF were observed in the 15°C treatment and lowest in the 25°C treatment. In contrast, for carbon, an equilibrium of muscle isotopic values was reached only in the natural ambient temperature regime. Presumably, discrimination of nitrogen isotopes was related to metabolic turnover rates, where all values were significant, while for carbon, only significant values were found under natural ambient temperature conditions. These findings highlight the importance of considering environmental thermal conditions in evaluating stable isotope signatures in trophic studies.

EXPRESSION OF CONCERN: Ultrastructural and Hormonal Changes in the Pineal–Testicular Axis Following Arecoline Administration in Rats

Tue, 24 Feb 2026 19:05:38 -0800

EXPRESSION OF CONCERN: I. Saha, U. Chatterji, S. Chaudhuri-Sengupta, et al. 2007. “Ultrastructural and Hormonal Changes in the Pineal–Testicular Axis Following Arecoline Administration in Rats.” Journal of Experimental Zoology – A 307A, no. 4: 187–198, https://doi.org/10.1002/jez.354.

This Expression of Concern is for the above article, published online on 08 March 2007 in Wiley Online Library (wileyonlinelibrary.com), and has been issued by agreement between journal Editor-in-Chief, Randy Nelson and Wiley Periodicals LLC. A third party raised the following concerns: that the image in Figure 3D had been duplicated in another article [Saha et al. 2011 (https://doi.org/10.1016/j.taap.2011.06.010)] and that portions of the image in Figure 2H and portions of the images in Figures 3A and 3B had been duplicated and manipulated in other articles [Saha et al. 2017 (https://doi.org/10.1080/13813455.2017.1352605), Saha et al. 2018 (https://doi.org/10.1080/13813455.2018.1486428), and Cydalima laticostalis 2025 (https://pubpeer.com/publications/1954237BA2AFC72EE913C316CC3BCC)]. All articles included many of the same authors and each described different experimental conditions.

An investigation by the publisher confirmed these concerns and also found that the images in Figures 3A, 3C, and 3E had been duplicated in another article by many of the same authors [Saha et al. 2015 (https://doi.org/10.1155/2015/136738)]. The authors did not respond to an inquiry and request for original data by the publisher.

The editors and publisher have determined that, while this article represents the earliest known publication of the data in these figures, the re-use and manipulation of data, as well as the representation of data as different samples in future publications, casts doubt on the accuracy of the data reported in this article. The Expression of Concern has been agreed to in order to inform and alert readers about the results of the investigation. The authors were informed about the Expression of Concern.

Multi‐Year Assessment of the Effects of Tourism on Physiological Parameters of the Northern Bahamian Rock Iguana (Cyclura cychlura)

Wed, 11 Feb 2026 22:35:03 -0800

ABSTRACT

Humans continue to influence the behavior, physiology and overall status of wildlife, yet how these influences persist over time are not fully understood and likely vary across circumstance and species. Interactions specifically associated with ecotourism and food provisioning have the potential to impact the behavior and physiology of wildlife significantly, especially when it includes the practice of feeding. To better understand whether ecotourism-induced changes in physiology persist over time and the resulting on-going impacts on populations, monitoring across time is needed. We measured immune, energetic, and traditional stress metrics of two Northern Bahamian Rock Iguana (Cyclura cychlura) subspecies (C. c. inornata and C. c. figginsi) across several years in response to body condition and reproductive status, in six insular populations of varying degrees of tourist visitation. We used plasma samples to quantify energy metabolites, immune function, oxidative stress, and plasma corticosterone concentration. Reproductive status in females was a consistently important explanatory factor for oxidative stress, energy metabolites, and bacterial killing ability. For both subspecies, populations with no tourist visitation consistently had lower levels of oxidative stress, bacterial killing ability, and energy metabolites than those that experienced moderate to high levels of tourism, but they also had demonstrated higher levels of corticosterone. Corticosterone and bacterial killing ability varied across years, suggesting that annual differences in physiology are likely to play an important role in long-term population health. Given the impacts of human activity on animal health over time, continual population monitoring of multiple physiological health metrics is needed for greater insight into the long-term impacts of anthropogenic factors on vulnerable species.

Corrigendum to “Geographic Variation in Incubation Temperatures Promoting Viable Offspring Production in Broadly Co‐Distributed Turtles”

Wed, 28 Jan 2026 20:04:11 -0800

Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, EarlyView.

The Role of Endoplasmic Reticulum Stress and Unfolded Protein Response in Glucocorticoid Production

Wed, 07 Jan 2026 22:26:03 -0800

ABSTRACT

An optimal glucocorticoid stress response is essential because it allows animals to adjust their phenotype to constantly changing environments. Considerable progress has been made regarding our understanding of how various cellular mechanisms of glucocorticoid action modulate animals' stress response phenotype. However, a potentially overlooked mediator of glucocorticoid production and individual's stress response phenotype is the endoplasmic reticulum (ER) and its unfolded protein response (UPR), given that all steroid hormones are synthesised within the mitochondria and the ER. We hypothesise that UPR regulates glucocorticoid synthesis, and ER stress induction would inhibit glucocorticoid production in the adrenal cortex. We conducted in vivo and in vitro studies using outbred deer mice Peromyscus maniculatus and Y-1 adrenal cell lines respectively to investigate the effects of ER stress and UPR on adrenocorticotropic hormone induced glucocorticoid production. Specifically, we tested if induction and alleviation of ER stress using tunicamycin and tauroursodeoxycholic acid, respectively, would affect corticosterone production in deer mice and Y-1 cells and the protein expression of a steroidogenic enzyme in Y-1 cells. We showed that ER stress and UPR modulate glucocorticoid production at both the cell and whole-organism levels, but this is achieved independent of alteration in protein level of 21-Hydroxylase.

In Memoriam ‐ David P. Crews

Wed, 03 Dec 2025 05:15:40 -0800

Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, EarlyView.

RETRACTION: Melatonin Counteracts Cadmium‐Induced Rat Testicular Toxicity via the Mechanistic Target Rapamycin (mTOR) Pathway

Tue, 18 Nov 2025 19:53:06 -0800

RETRACTION: M. B. Rhouma, M. Venditti, A. Haddadi, L. Knani, L. Chouchene, S. Boughammoura, R. J. Reiter, S. Minucci, and I. Messaoudi, “Melatonin Counteracts Cadmium-Induced Rat Testicular Toxicity via the Mechanistic Target Rapamycin (mTOR) Pathway,” Journal of Experimental Zoology – A 341, no. 4 (2024): 470–482. https://doi.org/10.1002/jez.2792.

The above article, published online on 04 March 2024 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Randy Nelson and Wiley Periodicals LLC. A third party reported that a version of the DAPI/PNA/CX43 panel in Figure 4b had been copied and rotated as the Cd panel in the same figure. The third party also reported that the CM (−Pr), CMR (+ Pr), and Rapa (+ Pr) panels in Figure 6 A contained similar image elements following image manipulation and rotation. Further investigation by the publisher found the presence of similar cellular sections across the CM panel in Figure 2B and the MLT panel in Figure 3B. This investigation also found that the beta-actin bands had been duplicated between Figures 2A and 4A.

The authors responded to an inquiry by the publisher, acknowledged errors in Figures 2B, 3B, 4B and 6A, and stated that these mistakes were made during figure assembly. The authors provided what were labeled as original data for Figures 2, 3, 4, and 6 and supplied corrected images. Upon review of these data, the parties determined that while errors in figure assembly could explain the errors in Figures 2, 3, and 4, the authors did not provide a satisfactory explanation for the errors in Figure 6.

The retraction has been agreed to because the number of errors in image assembly, as well as evidence of image manipulation, fundamentally compromises the editors' confidence in the results presented in the article. The authors did not respond to the notice regarding the retraction.

Developmental Heat Conditioning Alters the Adult Glucocorticoid Response and DNA Damage While Mediating Lifespan Variation in Zebra Finches (Taeniopygia Castanotis)

Thu, 28 Aug 2025 04:34:35 -0700

ABSTRACT

Developmental stressors may result in adaptive adjustments in physiology, increasing fitness later in life in otherwise damaging environments. Environmental conditions during development can permanently alter the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis, which may allow organisms to avoid cellular damage in stressful conditions. We hypothesized that zebra finches (Taeniopygia guttata castanotis) thermally conditioned during development will have lower baseline plasma corticosterone (cort) and baseline erythrocyte DNA damage as adults, as well as lower post-stressor cort and DNA damage, and higher survival rates following a thermal stressor in adulthood compared to juvenile controls. To test this, we exposed juvenile male and female zebra finches to a mild heat (38°C) or control (22°C) temperature every other day for 28 days. As adults, these finches were then subjected to either a high heat stressor (42°C) or control (22°C) temperature for 3 consecutive days. We measured plasma cort levels and erythrocyte genomic DNA damage before and at the end of each treatment period. As adults, the heat-conditioned juvenile finches had higher baseline DNA damage levels, persistently higher body masses, and lower cort levels 4 h following the adult high heat stress treatment compared to juvenile controls. Moreover, this cort phenotype was associated with reduced body mass loss and increased survival rates. However, females had reduced survival if they were not also exposed to the high heat treatment as adults. Our results demonstrate adaptive developmental plasticity in cort levels; however, this phenotype may be detrimental when there is an environmental mismatch.

Correction to “Interactive Effects of Temperature Acclimation and Dietary Fatty Acids on Metabolic Rate and Body Composition of Zebra Finches (Taeniopygia guttata)”

Tue, 19 Aug 2025 21:20:24 -0700

Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, EarlyView.

Maintenance of Physiological and Molecular Processes Through Food Restriction During Offspring Provisioning in the Adult Zebra Finch

Tue, 12 Aug 2025 00:00:00 -0700

ABSTRACT

Food restriction is a common environmental stressor, and it can have beneficial effects such as increased longevity when applied to non-reproducing adults. At the molecular level, food restriction can have beneficial effects through increased DNA repair, reduced DNA damage and longer telomeres, but a lack of food may also hinder the ability to utilize carotenoids, or antioxidants obtained from diet. When food restriction overlaps with a period of high energetic demand, such as during offspring provisioning, a combination of the two may instigate reproductive trade-offs. In this study, adult zebra finches (Taeniopygia guttata castanotis) were exposed to either ad libitum (control) or 40% restricted (food-restricted) diet while raising their young. Blood samples and beak pictures of parents were taken when birds were paired (before treatment), when their offspring fledged (~13 days on treatment), and when their offspring reached nutritional independence (~40 days on treatment). DNA was extracted from red blood cells to quantify telomere length and DNA damage, RNA was extracted from whole blood to quantify expression of DNA repair genes, and beak pictures were used to quantify beak color as a measure of carotenoids. We found that while provisioning their offspring, food-restricted birds increased the length of their telomeres, while controls did not alter telomere length. However, there was no effect of food restriction on DNA damage, gene expression of Pot1, Neil3, Aptx, or Hspa2, or beak color, and DNA damage and telomere length were not significantly associated with each other. The results of this study suggest that food-restricted parents provisioning offspring are behaviorally calorically restricting themselves and promoting genomic maintenance. Furthermore, the lack of significance in DNA damage and repair under food restriction suggests the relationship between telomeres, oxidative stress, repair mechanisms, and morphometric indicators of antioxidants under food restriction is complex and requires further exploration.

Chronic Stress Intensity Does not Affect Corticosterone or DNA Damage in Adult and Juvenile House Sparrows

Mon, 04 Aug 2025 03:29:15 -0700

ABSTRACT

One unanswered question in the field of stress physiology is how the pathology associated with chronic stress arises, such as increased baseline corticosterone, blunted stress-induced corticosterone, and increased levels of DNA damage. If the intensity of the stressor plays a role, we would expect high stress animals to develop pathologies such as these sooner or that is more severe than an animal experiencing less-intense chronic stress. To test this, we modified an applied chronic stress protocol in both adult and juvenile house sparrows (Passer domesticus) and monitored a physiological mediator, corticosterone, and an endpoint, DNA damage, of the stress response. We found that neither DNA damage nor corticosterone was sensitive to the intensity of chronic stress in both ages of birds. The high-stress adult birds had higher stress-induced corticosterone 6 weeks after the chronic stress period ended, potentially indicating that they were prepared for future stressors, while also avoiding pathology. High levels of corticosterone after ~ 3 weeks of an acclimation period and throughout the duration of this study indicate that the birds in this study may not have fully acclimated to captivity, potentially confounding the effects of a graded chronic stress protocol. Taken together with other data from this larger project, we show that not all physiological systems are affected by chronic stress equally and that some physiological changes may be caused by pathways other than the hypothalamic-pituitary-adrenal axis.

Maximum Free Glucocorticoids Link Natural Behavior and Stressors in a Wild Bird Population

Creagh W. Breuner, Joely G. DeSimone, B. Sunny Domschot, Thomas P. Hahn — Wed, 09 Jul 2025 22:49:40 -0700

Glucocorticoid reactivity to handling predicts territory abandonment during storms in a high-elevation population of white-crowned sparrows.

ABSTRACT

Glucocorticoids (GCs) regulate suites of traits that can have far-reaching consequences on reproduction and survival. While studies of GC effects on performance are common, results vary widely in their relationship to fitness. Focusing studies on performance metrics that have repercussions for both reproduction and survival may help clarify extended consequences of GC secretion. In this study we evaluated relationships between endogenous GC reactivity, body condition, food availability, and breeding-site departure during storms in a population of white-crowned sparrows early in the breeding season, asking whether GC secretion in response to our capture and handling challenge predicts natural behavioral responses to inclement weather, and whether food availability influences that decision. Our data support a role for GC reactivity in decisions to abandon nascent territories, in that more reactive individuals—those with higher free CORT in response to capture and handling stress—depart sooner during storms. In this case only free GCs (unbound to corticosteroid binding globulin) predict behavior, supporting the hypothesis that free hormone in the plasma is the biologically active fraction. We also suggest a role for food availability in these decisions, as males that located a supplemental food source did not depart during a storm. The very small sample size in the feeding study, however, limits any broad conclusions. All together these data (1) link GC reactivity (free max GC) to a naturally-induced behavior, and (2) support that individual variation in GC elevation has consequences for trade-offs in survival and reproduction.

Repeated Experimental Cold Exposure During Early Life Affects Several Metrics of Success but not Telomeres in a Common Songbird

Anuj Ghimire, Rebecca C. Young, David F. Westneat, Britt J. Heidinger — Mon, 19 May 2025 00:49:56 -0700

ABSTRACT

Climate change is increasing temperature variability and exposure to extreme temperature events, including cold snaps. Although there is evidence that exposure to cooler developmental temperature can have widespread phenotypic consequences, the degree to which temperature exposures might interact across developmental stages to affect offspring is poorly understood. Here we experimentally exposed free-living house sparrows to repeated bouts of parental absence, which cooled embryos and both cooled and deprived nestlings in a crossed design and examined the effects on growth, body mass, telomeres, and survival. We found that exposure to cooler temperatures during embryonic development had several negative consequences including extending incubation and reducing hatching success and body mass of recent hatchlings. However, there were no significant effects on telomeres. There were also no main effects of cooling and short-term food deprivation during post-hatching development or interactions across developmental stages on any developmental outcomes including telomeres. Taken together, these results suggest that some developmental stages and traits are more sensitive to repeated cooling than others. In songbirds, offspring may be more sensitive to repeated cooling at earlier life stages and telomeres may be largely resilient to these developmental insults.

Corticosterone and Mitochondrial Efficiency Are Associated With Changes in DNA Oxidative Damage During an Acute Stress Response in Leach's Storm‐Petrels (Hydrobates leucorhous)

Mon, 24 Mar 2025 01:45:04 -0700

ABSTRACT

The ability of organisms to effectively respond to challenges is critical for survival. We investigated how an acute stressor affected corticosterone, mitochondrial function, and DNA oxidative damage in a wild population of Leach's storm-petrels (Hydrobates leucorhous). We conducted a standardized 20-min handling procedure on storm-petrel chicks and collected baseline and post-handling blood samples. We measured plasma corticosterone and red blood cell DNA oxidative damage levels through the detection of a mutated DNA base 8-Hydroxy-2'-deoxyguanosine (8-OHdG). In addition, we quantified six measures of mitochondrial aerobic metabolism from red blood cells. Overall, the handling stressor increased plasma corticosterone levels and decreased mitochondrial efficiency to produce ATP. Although the increase in corticosterone was inversely related to the change in DNA oxidative damage, the decrease in mitochondrial efficiency was positively correlated with the change in DNA oxidative damage. Thus, over an acute stress response, individuals who had the largest increase in corticosterone also had the least amount of oxidative damage. In addition, individuals who prioritized ATP production during the acute stress also showed higher levels of oxidative damage. This work highlights the complex pathways by which corticosterone and mitochondrial efficiency affect oxidative damage during acute stress, providing new insights into the trade-offs underlying physiological responses in wild animals.