Journal of experimental zoology. Part A, Ecological and integrative physiology最新文献

Exposure to altered nighttime lighting conditions has become common in today's modern world. Light at night disrupts circadian processes that govern feeding patterns, sleep/wake cycles, and metabolic homoeostasis, increasing the risk of developing pathologies associated with cardiometabolic disease. Yet, the underlying mechanism(s) responsible for mediating the resulting physiological outcomes are not clear. Mitochondrial function may provide valuable insight into the physiological costs associated with light at night, given that mitochondria contribute to variation in metabolic performance that underpin human diseases. In this study, 36 male and female wild-derived house mice (Mus musculus) were exposed to continuous light, darkness, or a control light cycle for 6 weeks. We examined animals' bioenergetic capacity at the whole-organism and subcellular level while also measuring changes in body condition and oxidative damage. We found that 6 weeks of constant light and darkness resulted in negligible changes in all our variables of interest. We did not detect strong mitochondrial responses in the liver or skeletal muscle of either sex exposed to constant light or darkness. Furthermore, we did not detect any difference in mitochondrial volume or lipid peroxidation in the liver between treatment groups. Lastly, there was no difference in body condition between treatment groups. Our data indicate that wild-derived mice are able to circumvent challenges of an altered light environment and escape physiological consequences.

Immune-neuroendocrine characteristics can be used to classify individuals according to their physiological profiles or phenotypes (INPs). In avian models such as quail and domestic chickens, three subgroups based on INPs have been defined: Lewis-like (pro-inflammatory polarization), Fischer-like (anti-inflammatory polarization), and an intermediate INP. This study investigates the stability and alterations of INPs throughout ontogeny, from juvenile to adult stages in four time-points including an exposure to unpredictable and diverse chronic stress (CS) during early adulthood. We measured corticosterone levels, pro- (IFN-γ and IL-1β) and anti-inflammatory (IL-13, IL-4) cytokines, phytohemagglutinin (PHA-P) lymphoproliferative response, anti-sheep red blood cells antibody (Ab SRBC) response, and leukocyte distribution frequency. Cluster analyses were conducted to classify bird based on their similarities across all analyzed variables, to thereby establish their INP at each time point. The extreme Lewis- or Fischer-like profiles were less represented in juvenile and pre-stress adult birds showing a higher proportion of individuals with an intermediate profile. Following CS exposure, the prevalence of Lewis-like and Fischer-like profiles increased. This shift persisted 10 weeks later as birds matured to an advanced egg-laying stage, with females predominantly exhibiting the Fischer-like INP, and males the Lewis-like INP. The observed shift in INP distribution following CS towards more polarized Lewis- and Fisher-like profiles implies a more even representation of the three observed profiles and may reflect inter-individual differences in physiological response to CS associated to particular coping strategies. A more even INPs distribution could provide the population with a greater advantage when facing diverse environmental challenges.

Amphibians are the most threatened vertebrate class globally. Climate change, agrochemicals, and/or pathogens and parasites are implicated in contributing to amphibian declines, either singly or in combination. We investigated individual and combined effects of elevated temperatures and atrazine (2.0 μg/L) on Lithobates [formerly Rana] pipiens phenotypes, in a mesocosm experiment. We sampled tadpoles after 2 weeks, and other individuals at the completion of metamorphosis for endpoints relative to development, locomotor performance, immunity, and stress. Temperatures ranged from 7.18°C to 31.27°C over the experimental period, with a significant ~2°C difference between temperature treatments: warming and ambient. Whereas we found no effect of atrazine alone, we found strong effects of temperature, and some evidence of an interaction between atrazine and temperature on various phenotypic attributes. In tadpoles, elevated temperatures were associated with increased growth, accelerated development, and may have reduced stress, but decreased locomotor performance. Elevated temperatures also interacted with atrazine, offsetting an atrazine-mediated delay in tadpole development. In metamorphs, elevated temperatures accelerated development at the cost of reduced size, but did not influence locomotor performance. However, warming was associated with lowered immunity, reflecting a trade-off between growth and immune function. Elevated temperatures and atrazine also combined to affect metamorph neutrophil to lymphocyte ratios, reducing immunocompetency. Our results highlight the importance of incorporating multiple environmentally relevant stressors, thought important to amphibian declines in ecotoxicological studies, and of assessing multiple developmental stages.

Amphibians' skin secretes a wealth of bioactive compounds, vital for their survival and natural defense systems. This study employed a combined eco-physiological approach to investigate the ecological adaptation of Hylarana erythraea through metabolomic and peptidomic profiling of its skin secretions using mass spectrometry. Several extraction methods were used to capture the widest range of chemicals possible. The study identified 71 metabolites and 87 peptide pathways linked to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The metabolite profile was mostly composed of amino acid-derived compounds, with notable activity in antioxidant and immune pathways like methionine, spermidine, and betaine metabolism. Identified peptides were largely involved in innate immunity, stress response, and wound healing, with Gene Ontology terms related to T-cell and B-cell development, and KEGG pathways connected to environmental adaptation and signal transduction. Bioactivity predicted from the peptide sequences showed strong potential for treating diabetes, high blood pressure, and infections, as well as antioxidant effects previously shown by others. This integrated analysis emphasizes how skin secretions help amphibians interact with their environment and cope with stress. These findings support H. erythraea as a model for studying amphibian eco-physiology and demonstrate the usefulness of multi-omics in connecting biochemistry to adaptive function, with potential applications within the One Health context.

Embryos of Artemia franciscana survive harsh conditions in diapause and anoxia-induced quiescence for years by undergoing deep metabolic transitions. During reactivation of metabolism, both the release of reactive oxygen species (ROS) from mitochondria and oxidative damage in mitochondria are low compared to mammalian mitochondria. Because antioxidant pathways can be important for avoiding oxidative stress upon metabolic reactivation in some cases, part of the low ROS efflux from A. franciscana mitochondria could be attributed to scavenging. Consequently, we analyzed activities of antioxidant enzymes and quantities of small-molecule antioxidants in diapause versus post-diapause embryos under steady-state conditions. Functional capacities of most antioxidant enzymes (total superoxide dismutase [Cu/Zn-SOD + Mn-SOD], Mn-SOD, and glutathione reductase [GR]) were higher in the post-diapause state. These changes are understandable based on very elevated metabolic rates during post-diapause, and the correspondingly higher defense capacities necessitated against ROS. Conversely, quantities of reduced glutathione (GSH), along with the total GSH pool (GSH + GSSG), were higher during diapause. The depressed metabolic rates during diapause predictably foster lower ROS generation (oxidative stress) to impact the GSH pool, so the standing quantity of reduced species in the pool is greater. However, our literature survey suggests that, overall, A. franciscana embryos do not possess abnormally elevated defenses against oxidative stress when compared to other hypoxia/anoxia-tolerant species or even intolerant species. Thus, avoiding the actual generation of large ROS bursts after metabolic reactivation appears to be the more important contributor to protection of the embryos compared to ROS scavenging per se.

Nemertea is a speciose phylum of marine invertebrate predators ubiquitous in the world's oceans, which includes Lineus longissimus (Gunnerus, 1770)-the world's longest documented extant animal, yet much about the life histories of these remarkable animals remains poorly understood. For example, it is not known how long nemerteans live. We report a maximum known age of a nemertean individual, identified by morphology and DNA-barcoding as belonging to Baseodiscus punnetti (Coe, 1904), which has been kept in aquaria for at least 26 years. This finding confirms previous speculations that at least some species of nemerteans may live for many years and highlights a dearth of knowledge of the longevity of nemerteans and of marine invertebrates more broadly.

In ectothermic vertebrates, temperature impacts the rate and success of embryonic development, and in some species, embryos show adaptive behavioral responses to thermal conditions. The arboreal embryos of red-eyed treefrogs exhibit heat-induced hatching, escaping to cooler water below and demonstrating a limit to their behavioral thermal tolerance, or Voluntary Thermal Maximum (VT_Max). Their escape response to warming has been studied only at developmental stages 31-34 (age 5 days), although these embryos hatch in response to other threats as early as stage 24 (age 3 days). Hence, it is unclear when heat-induced hatching begins or how this behavior may change with further development. We conducted an ontogenetic series of warming trials to determine the onset of heat-induced hatching, assess developmental changes in the proportion of embryos that respond, and test whether expression of VT_Max changes with development. No embryo tested at stage 26 hatched; heat-induced hatching began in some clutches at stage 27. The proportion of embryos hatched increased from 3% at stage 27 (age 4.3 days) to 86% at stage 30 (5.4 days) when all clutches were responsive. The greatest variation in response among clutches occurred at stage 29. Hatching temperature was similar across stages 27-30 (38.2 ± 1.3°C) and consistent with the VT_Max reported for stage 31-34 embryos (38.1 ± 0.8°C) under similar testing conditions. These findings provide new insights into the ontogeny of heat-induced hatching behavior and reveal that embryos can escape from heat more than a day earlier than previously shown. The ontogenetic stability of VT_Max suggests a consistent thermal threshold guiding this response, providing reliable protection against lethal temperatures. This plasticity may help embryos withstand increasing thermal stress under climate change.

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.

In fish, sex determination and gonadal development are controlled by various genetic and environmental factors. In this study, experiments were conducted on the estuarine mummichog (Fundulus heteroclitus) to investigate gonadal differentiation following exposure to the synthetic estrogen, 17α-ethinylestradiol (EE₂). The period of sensitivity to EE₂ was explored by initiating the exposures at different times post fertilization. In Experiment 1, mummichog embryos were collected within 8 h of fertilization and then continually exposed to increasing concentrations of EE₂ (up to 229 ng/L) for up to 10 weeks. For controls, complete differentiation of the gonad to a testis or ovary in mummichog occurred by 3 weeks post hatch (wph) and there was an equal distribution of males and females. Exposure to all concentrations of EE₂ accelerated female gonadal differentiation as early as 1 wph and contributed to a highly female skewed sex ratio with 80% to 100% of the fish displaying ovaries. Exposure to EE₂ also resulted in a concentration-dependent increase in skeletal abnormalities and mortalities whereas larval lengths were not affected. In Experiment 2, 24 h post-hatch larvae were exposed for 5 weeks to three treatments with measured concentrations (ng/L) of 0.4 (Control), 2.5 ng/L, and 18.0 ng/L). The sex ratio was approximately 50/50 in controls and did not change with EE₂ treatment. EE₂ did not alter the proportion of oocyte stages (chromatin nucleolus, perinucleolar, cortical alveolar) but spermatogenesis was impeded as male fish had greater proportions of spermatogonia, and spermatids were only observed in controls. EE₂ treatment did not change the expression of genes in the ovary implicated in gonadal development including cyp19a1a, foxl2, gdf9, bmp15, dmrt1, and amh. In contrast, testis expression of dmrt1 was decreased and cyp19a1a, foxl2, gdf9, and amh were increased following EE₂ treatment. Overall, by the time of hatching (about 3 weeks post fertilization), sex differentiation was complete, and the sex determination mechanisms were only sensitive to EE₂ during a window of embryonic development before hatch. Early stages of testis differentiation may be more sensitive to exogenous EE₂ exposure than ovarian tissue in the mummichog.

General stress-response of vertebrates to fluctuations of environmental conditions are conservative, and includes rapid release of neurotransmitters into blood. In amphibians, physiological effects of catecholamines (CA) on red blood cell (RBC) functions have been studied fragmentally despite the presence of adrenoreceptors on RBC membranes. In the present work the influence of epinephrine on RBC stability to hypoosmotic stress as well as intracellular reactive oxygen species (ROS) production levels and mitochondrial membrane potential have been studied on RBCs of marsh frogs Pelophylax ridibundus (in vitro). Additionally, the involvement of cAMP/Adenylate cyclase/protein kinase A (cAMP/AC/PKA) pathway in regulation of these processes have been evaluated. We showed that increase of RBC stability to hypoosmotic shock is mediated by activation of β-adrenoreceptors and independent from cAMP/PKA pathway. Lysis of RBCs treated with epinephrine occurred at lower osmolarities compared to non-stimulated cells and changes in RBC membrane properties were rapid (after 5 min incubation) and stable (following 60 min incubation). Addition of epinephrine to RBC suspensions or activation of cAMP/AC/PKA pathway (forskolin and cBIMPS) was associated with a reduction of ROS concentration in cytoplasm and enhanced mitochondrial membrane potential. The results of the present work provide novel insights into the cellular mechanisms of adrenergic RBC stimulation and pathways involved into signal transduction within the context of environmental stress. Stimulating effects of epinephrine on RBC membrane stability and mitochondrial activity is probably important for adaptation of frogs to unfavorable habitat conditions, seasonal activity and other stress factors.