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

The serine/threonine phosphatase PP1γ2 plays a critical role in modulating epididymal sperm maturation and motility. Our previous work demonstrated that PP1γ2 regulates these processes in tree shrews via phosphorylation and dephosphorylation. This study further investigates the interactions among PP1γ2, SRC tyrosine kinase, and protein kinase A (PKA), along with their molecular mechanisms in regulating epididymal sperm motility in tree shrews.Using Western blotting, immunokinase assays, co-immunoprecipitation, and Ser/Thr phosphatase activity assays, we characterized key signaling dynamics. Results showed that Ser/Thr phosphatase activity was significantly higher in caput than in cauda epididymal spermatozoa (p < 0.05). Inhibiting PKA and SRC significantly increased Ser/Thr phosphatase activity and reduced cauda sperm motility (p < 0.05). Conversely, SRC activation with sc-3052 significantly reduced phosphatase activity in caput sperm (p < 0.05). We also found that SRC interacts with PP1γ2 in caudal sperm, and that both SRC and PKA activities were higher in caudal than in caput sperm, with SRC acting downstream of PKA. These results suggest that SRC kinase regulates sperm motility by inhibiting PP1γ2-mediated Ser/Thr phosphatase activity, under the regulatory control of PKA. This study provides a foundation for further investigation into PP1γ2's functions and reproductive regulatory mechanisms in tree shrew sperm.

Infectious diseases represent a major threat to the survival of endangered sea turtles. The immune response in these animals is configured early in development and is heavily influenced by the incubation environment. While maternal traits are known to influence offspring immune function in some reptiles, their role in shaping immune responses in sea turtle hatchlings remains poorly understood. The hemolytic capacity, a key component of the innate immune system, shows stability across incubation environments, suggesting that it might be shaped by maternal factors rather than by environmental variation. Herein, the relationship between the hemolytic capacity of hatchlings challenged with lipopolysaccharide (LPS) and maternal characteristics, including hemolytic response and body size, was studied. Blood samples and morphologic measurements were collected from nesting females over 2 years. Each clutch was entirely relocated to individual shaded nests for incubation. Upon emergence, one hatchling per nest was injected intraperitoneally with phosphate-buffered saline (PBS) and another hatchling with LPS. 4 h later, hatchlings were euthanized and blood samples were collected. The results showed that hatchling's hemolytic capacity was positively associated with maternal hemolysis and body mass, but negatively linked to maternal straight carapace length. Lipopolysaccharide challenge did not significantly modify the hemolytic capacity of hatchlings. Although based on a limited sample size due to the species’ protected status and technical constraints of ecoimmunological research in wild animals, these findings suggest a possible influence of maternal attributes on offspring immune function. They also suggest that hemolytic capacity is a robust early-life immune defense in hatchlings.

Light is an important factor affecting the behavior and physiology of organisms. As a phototactic organism, studying the effects of different colors of light on the mating, development, and reproduction of Drosophila melanogaster helps elucidate the important influence of spectral sensitivity on organisms. This study explored the effects of white light (400 lux, control), green light (400 lux, wavelength to which fruit flies are most spectrally sensitive), red light (400 lux, wavelength to which fruit flies are least spectrally sensitive), and dim-green light (225 lux, green-band irradiance matched to the white control) on the sexual vitality, development, and reproductive capacity of fruit flies under group-housed conditions. The results revealed that 1 h of green light exposure per day significantly shortened mating latency and mating duration, accelerated pupation time, raised the egg‑to‑pupa conversion rate, and increased the number of offspring. In contrast, there was no significant difference in various indicators between the white, red, and dim-green light groups. This study explored the important role of light intensity and spectral sensitivity in regulating the mating and reproduction processes of fruit flies and provides more evidence for comparative research on the behavioral and physiological effects of light on different organisms.

Exercise is crucial for animal survival, enabling them to move, forage, and meet survival needs, as well as maintain fitness and adapt to the environment. The present study aims to explore the effects of long-term forced exercise on the body mass, energy metabolism, and liver metabolomics of Apodemus draco to understand its physiological adaptation mechanisms under exercise stress. Before exercise acclimation, body mass, resting metabolic rate (RMR), non-shivering thermogenesis (NST), and food intake of A. draco in exercise and control groups were measured. After an 8-week exercise acclimation period, these physiological parameters and liver metabolic indices were re-measured. Results showed no significant body mass difference between groups. However, the exercise group had a significant decrease in body fat content (p < 0.01) and serum leptin level (p < 0.01), with a positive correlation between them. RMR and food intake in the exercise group were significantly higher (p < 0.01). Mitochondrial protein (MP) content and cytochrome c oxidase (COX) activity in the liver of exercised animals increased significantly (p < 0.05), while NST and brown adipose tissue-related indicators remained unchanged. Principal component analysis (PCA) of liver metabolites revealed distinct separation between the two groups, indicating good data quality. Differential metabolite analysis showed significant upregulation of metabolites related to lipid, amino acid metabolism, and the tricarboxylic acid (TCA) cycle in the exercise group, like docosahexaenoic acid, glyceric acid, and so forth. In conclusion, long-term forced exercise didn′t significantly affect A. draco′s body mass, but increased energy intake by reducing body fat and leptin levels. It enhanced RMR and liver mitochondrial metabolic activity, increased obligatory thermogenesis without affecting adaptive thermogenesis, and maintained body weight stability. Liver metabolomics changes suggested multi-dimensional metabolic adaptations of A. draco to exercise. This study provided new insights into the physiological adaptation mechanisms of small rodents under exercise stress.

Temperature is a key environmental factor influencing the establishment and spread of insect species. Differences in thermal tolerance may thus explain patterns of geographical distribution and dominance during biological invasions. The native Patagonian bumblebee, Bombus dahlbomii, is being displaced by the exotic Bombus terrestris, which has expanded throughout its range. To investigate the role of cold tolerance in this context, we first examined the minimum temperatures likely to be encountered by both species across their South American distribution. Then, we assessed whether these minimum temperatures correlated with their cold tolerance, measured as chill coma onset and recovery temperatures. We found that, despite experiencing similar minimum temperatures in their ranges, B. dahlbomii is more cold tolerant than B. terrestris: the native bumblebee reaches lower ambient and body temperatures before entering chill coma and recovers at lower body temperatures. Exploring possible mechanisms of cold tolerance, we found that the larger body size and longer body hairs of B. dahlbomii compared to B. terrestris may represent traits evolved to prevent heat loss. However, after evaluating the daily foraging window modeled on the species' cold tolerance in northwestern Patagonia, we found it does not appear to confer a substantial temporal advantage in this region. Therefore, the dominance of B. terrestris in Patagonia cannot be explained by cold tolerance. In fact, native bumblebees exhibit greater physiological and morphological adequation to cold. The success of B. terrestris is likely driven by other factors, including heat tolerance, disease resistance, or differences in life history traits such as colony size.

The vomeronasal organ (VNO) is a key receptor for pheromones involved in regulating reproductive and social behaviors in animals, such as mating between males and females and male-male competition. The aim of this study was to explore variations in circulating androgen and estrogen concentrations in male muskrats in relation to seasonal changes in vomeronasal function. Phylogenetic analysis revealed a total of 212 vomeronasal receptor (VR) genes in muskrats. Previous experimental results demonstrated that among these genes, VN1R41 and VN2R1 act as potential VNO receptors to mediate chemical communication behaviors in muskrats. Therefore, we selected VN1R41 and VN2R1 as representatives of VRs for subsequent experiments. Molecular docking simulations showed that VRs can bind to sex steroid hormones and their sulfated derivatives. Circulating concentrations of testosterone (T), dihydrotestosterone (DHT), and 17β-estradiol (E₂) increased significantly during the breeding season. Type 1 vomeronasal receptors (V1Rs), type 2 vomeronasal receptors (V2Rs), P450arom, androgen receptor (AR), estrogen receptor α (ERα), and estrogen receptor β (ERβ) were detected in both sensory and non-sensory epithelial cells of the VNO in male muskrats. Immunofluorescence assays of VNO also revealed AR and ERα signals in sustentacular cells and sensory cells of the sensory epithelium. The messenger RNA (mRNA) expression levels of VN1R41, AR, ERα, and P450arom in the VNO were significantly higher during the breeding season compared with the nonbreeding season, whereas the mRNA expression levels of VN2R1 and ERβ were lower. Additionally, transcriptomic analysis revealed that differentially expressed genes might be associated with estrogen signaling pathways. These results suggest that androgens and estrogens may regulate vomeronasal function through the expression of AR, ERs, and VRs in the VNO of male muskrats.