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

Understanding the physiological mechanisms that define species' thermal tolerance is critical for predicting the impact of ocean warming on marine biodiversity. We investigated multiple thermal threshold parameters in the Jonah crab, Cancer borealis, integrating laboratory-derived physiological and molecular data with field-based ecological distribution modeling. Crabs were subjected to acute and chronic temperature challenges while monitoring heart rate, ventilation rate, hemolymph oxygenation, motor activity, and lactate accumulation. Gene expression of heat shock proteins (HSP70, HSP90A, HSP90B) and transient receptor potential (TRP) ion channel subfamilies were quantified via qPCR. These physiological and molecular thresholds were compared with generalized additive models (GAMs) relating C. borealis presence to bottom temperatures across the U.S. Northeast Shelf. Heart rate increased steadily to 29 °C before failure, while ventilation showed distinct breakpoints at 14 °C and 25.5 °C. Hemolymph oxygen levels peaked between 7 °C and 20 °C, coinciding with optimal motor activity and minimal lactate accumulation, indicating a transition from aerobic to anaerobic metabolism above 20 °C. Gene expression of HSPs and TRPs exhibited tissue-specific, temperature-dependent trends with high variability. Ecological modeling revealed peak C. borealis occurrence at 11 °C-14 °C with declining probability above 15 °C, matching some experimentally derived physiological optima. Our integrative analysis demonstrates that no single physiological parameter fully defines the species' thermal limits; however, hemolymph oxygenation and motor activity most closely align with field-based distribution patterns. These results are somewhat consistent with the oxygen- and capacity-limited thermal tolerance (OCLTT) framework but highlight the utility of a multi-parameter approach consistent with the Multiple Performances-Multiple Optima (MPMO) concept.

In this study, the nuclear factor kappa B inhibitor delta gene (NFKBID) of the starry flounder, Platichthys stellatus, was identified through next-generation sequencing (NGS) and verified by cloning and sequencing. The multiple sequence alignment and phylogenetic analysis revealed high conservation of NFKBID among several fish species. The tissue distribution of NFKBID in healthy P. stellatus was analyzed by quantitative PCR, revealing expression in almost all tissues, with relatively high levels in the gills, skin, and trunk kidney. Furthermore, significant changes in NFKBID expression were observed in starry flounder following infection with Streptococcus parauberis PH0710 and viral hemorrhagic septicemia virus (VHSV). Infection with S. parauberis PH0710 downregulated NFKBID in most tissues except the intestine. In contrast, VHSV infection showed a significant upregulation of expression in most tissues during the early phase. These results suggest that immune-related responses to bacterial and viral infections in starry flounder are associated with changes in NFKBID expression. This study provides fundamental molecular insights into the potential involvement of NFKBID in immune-related processes in teleost fish.

Growing public concern regarding cetacean welfare has emphasized the need for developing robust, science-based tools for welfare assessment applicable across diverse species and settings. Within this context, in a broader effort to advance the validation of novel physiological indicators for monitoring cetacean welfare, this study optimized a non-invasive epidermal sampling method in killer whales (Orcinus orca; N = 5) and validated AlphaLISA immunoassays for quantifying epidermal cortisol (ECC) and oxytocin (EOC) concentrations. Analysis of body location as a potential confounding factor revealed notable intra-individual variability and lateral asymmetry in hormone concentrations, highlighting the importance of standardized sampling procedures. Significant associations emerged between both hormones and negative welfare indicators, while EOC was also linked to positive behavioral engagement and body weight variation. When considered alongside previous findings, ECC may represent a reliable and feasible biomarker for assessing retrospective, intermediate-term welfare changes in killer whales, particularly when embedded within a broader, multifactorial framework that integrates complementary indicators. By contrast, EOC remains less reliable at this stage, largely due to the limited understanding of the oxytocinergic system and its involvement in both positive and negative affective states. Future research involving larger populations, detailed welfare assessments, and improved understanding of epidermal hormone incorporation dynamics will enhance the practical utility of ECC and EOC as welfare biomarkers in cetaceans.

Amphibians, like other ectotherms, must balance conflicting demands for energy expenditure, physiological processes, and behaviour in response to environmental temperature variations that influence their survival and reproduction. Understanding these dynamics is crucial for assessing amphibians' resilience to climate change and identifying the stressors they face in their thermal environments. Our study investigated the influence of ambient temperature (T_a) on resting metabolic rate (RMR) in adult Rana temporaria and how the frogs' thermoregulatory reality in the field (field body temperature, T_b) while being active aligns with their responses to a wider range of temperatures in a thermal gradient (preferred temperature, T_pref). As anticipated for ectotherms, the RMR increased with T_a, doubling with each 10 °C increment, in accordance with the Q₁₀ coefficient. Consequently, absolute changes in RMR increased with increasing temperature. In the thermal gradient experiment, frogs primarily selected temperatures around 25 °C. At this temperature, which is not too far from the critical maximum temperature (CT_max) of 30 °C, RMR was 0.106 mL O2 g^-1 h^-1. The mismatch between actual field T_b and laboratory T_pref highlights the constraining influence of other environmental factors such as favourable microhabitat availability or hygric conditions. This study suggests an effective balance between energy requirements and thermoregulatory behaviour in R. temporaria, if favourable conditions are available. However, it also shows that the environmental reality of animals often deviates from unimpeded preferences of active individuals and thus results from experimental procedures might not necessarily reflect the situation in the field.