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

Testicular ischemia/reperfusion injury (TI/RI) is a significant clinical contributor to subfertility and infertility resulting from testicular torsion and subsequent detortion. Insufficient nitric oxide (NO) synthesis in TI/RI can result in endothelial dysfunction, as the vascular endothelium fails to produce sufficient NO to sustain appropriate vasodilation and blood perfusion. Many studies have found that NO plays an important role in the I/RI and its increase or decrease can affect the progression and outcome of I/RI. However, the role of NO in I/RI is controversial and complicated. NO derived by endothelial NO synthase (eNOS) shows a protective role in I/RI, while excessive NO derived by inducible NO synthase (iNOS) accelerates inflammation and increases oxidative stress, further aggravating I/RI. Nevertheless, the overexpression of eNOS may exacerbate I/RI. Here we try to investigate the new progress in the understanding of the roles of NO during I/RI. This study examined the interplay between cytotoxic and cytoprotective mechanisms underpinning NO produced from L-citrulline (L-Cit) on TI/R injured rats. Thirty-two adult Sprague-Dawley albino rats were equally randomized into the following groups: normal control group, sham group, TI/R group (3 h/4 h), and TI/R + L-Cit group (600 mg/kg) orally at 1 h before reperfusion. Compared to the TI/R-operated group, the injection of L-Cit markedly enhanced serum concentrations of reproductive hormones (p < 0.05). Elevated SOD, CAT, and GPx activity, along with reduced MDA and NO concentrations, indicated a diminished oxidative stress. The testicular levels of TNF-α, IL-1β, caspase-3, BAX, eNOS, iNOS, and NF-κB p65 were markedly reduced. Histopathological analysis corroborated the protective effect of L-Cit. The findings confirmed molecular models, demonstrating that L-Cit inhibited eNOS, iNOS, and IKKβ. The results showed that giving torsioned rats NO made from L-Cit protected them against hormonal imbalance, oxidative stress, inflammation, and apoptosis in I/RI. This makes L-Cit even more important for protecting against tissue I/RI during surgery. L-Cit not only promoted NO synthesis through eNOS activation, but it also facilitated the neutralization of iNOS production and its pathogenic NO levels during the reperfusion phase in I/R-injured rats.

In the integrated rice-crayfish aquaculture systems, crayfish Procambarus clarkii need to spend a long winter in the ring ditch, which is vulnerable to low temperature stress, especially in the northern part of China, where cold waves and other low-temperature climates are frequent. To study the metabolic response of P. clarkii to low temperature stress experimentally, the temperature was lowered from the control (23°C) to the low temperature group (9°C, 5°C, and 1°C) by slow and uniform cooling, and molecular and physiological samples were collected for measurement. The results showed that low temperature stress damaged the gill membrane and the epithelial layer of gill tissues, with an increase in vacuoles area and a reduced and irregular distribution of hemocytes. As the temperature decreased, the oxygen consumption rate, ammonia excretion rate and maximum metabolic rate of P. clarkii decreased gradually, the oxygen-nitrogen ratio decreased but still remained at a high level, and the metabolic energy supply substances were always mainly lipids and carbohydrates. The pyruvate kinase activity tended to increase with decreasing temperature under low temperature stress, while hexokinase, succinate dehydrogenase and lactate dehydrogenase activities decreased gradually. The 183 differential metabolites were screened in the low temperature group compared with the control mostly enriched in amino acid metabolism and citrate cycle metabolic pathways. In conclusion, under low temperature stress, the gill was damaged, respiratory metabolism decreased, and glycolysis was enhanced. Since the citrate cycle metabolism was suppressed, P. clarkii needed to resist low temperature stress by increasing the amino acid metabolism to provide more energy to maintain cellular activity. The results unraveled metabolic response mechanisms of metabolic response mechanism of P. clarkii to low temperature stress, and provided theoretical references for the selection and breeding of low-temperature-tolerant strains of P. clarkii.

Suspensory locomotion differs significantly from upright quadrupedal locomotion in mammals. Nevertheless, we know little concerning joint kinematics of suspensory movement. Here, we report three-dimensional kinematic data during locomotion in brown-throated three-toed sloths (Bradypus variegatus). Individuals were recorded with four calibrated high-speed cameras while performing below-branch locomotion on a simulated branch. The elbow (range 73°-177°; mean 114°) and knee (range 107°-175°; mean 140°) were extended throughout support phase, with elbow extension increasing with speed. Both the fore- and hindlimb displayed abducted proximal limb elements (i.e., arm and thigh) and adducted distal elements (i.e., forearm and leg) during all support phase points. Comparisons of elbow and knee angles between brown-throated three-toed sloths and Linnaeus's two-toed sloths (Choloepus didactylus) showed that brown-throated three-toed sloths had significantly more extended joint positions during all support phase points. Additionally, across all kinematic measurements, brown-throated three-toed sloths showed significant differences between homologous fore- and hindlimb segments, with the knee being more extended than the elbow and the arm being more abducted than the thigh. These results are consistent with previously established morphological and behavioral differences between extant sloth genera, with three-toed sloths showing significantly longer forelimbs than hindlimbs and typically favoring locomotion on angled supports. Our findings show that, despite overall similarities in the use of below-branch quadrupedal locomotion, the two sloth lineages achieve this locomotor mode with differing kinematic strategies (e.g., degree of joint flexion). These differences may be attributed to the distinct evolutionary pathways through which obligate suspensory locomotion arose in each lineage.

Studies examining the oxygen dependency of embryonic survival, growth, and differentiation have been conducted for decades in a diverse array of animal taxa but including only one oviparous snake, the viperine water snake Natrix maura. Here, we describe a study incubating eggs of the tiger keelback Rhabdophis tigrinus lateralis (Colubridae) under four oxygen conditions, hypoxia (7% and 11% O₂), normoxia (21% O₂), and hyperoxia (31% O₂), for different lengths or at different stages of incubation. The length of hypoxic exposure is important in affecting embryonic development in R. t. lateralis, with prolonged hypoxic exposure retarding embryonic growth and differentiation, increasing embryonic mortality and deformity, reducing hatchling size and mass, and altering hatchling body shape relative to normoxic controls. Embryonic tiger keelbacks are most susceptible to hypoxia late in development, as revealed by the fact that a 5-day exposure of eggs to hypoxia of 7% O₂ reduced embryo mass and hatchling mass if it occurred at late stages of incubation. Hyperoxia of 31% O₂ did not enhance development of R. t. lateralis embryos, only affecting hatchling head width, which slightly differed between hyperoxic hatchlings and their normoxic siblings. This study demonstrates the importance of avoiding hypoxic exposure at late stages of embryonic development in snakes.

Stress during development can elicit lifelong changes to an organism. However, whether these changes are beneficial or detrimental can only be determined by their effect on fitness outcomes. Furthermore, the effect of severe, chronic food restriction on the development of ornamentation, which can influence attractiveness, still needs to be explored. In this study, zebra finches (Taeniopygia castanotis) were exposed to either an ad libitum (control) diet or a 40% restricted (food-restricted) diet throughout postnatal development. Pictures of beaks and cheek patches were captured throughout the juvenile period and into adulthood to measure the development of secondary sexual characteristics. In adulthood, females were paired with nonexperimental males to measure reproductive success. There was no effect of treatment on beak color development or final beak color, but food-restricted males developed cheek patches slower and had more asymmetry during cheek patch development. However, food restriction did not impact the final cheek patch color or size. Food-restricted females were found to have lower reproductive success than control females. These results suggest that while cheek patch ornamentation can experience 'catch-up growth', and beak and cheek patch color do not reflect past developmental stress exposure, developmental food restriction impairs female reproductive success in a short-lived passerine.

Water availability has critical impacts on numerous physiological functions in all organisms and can have different effects across life stages. For example, water available to reproductive females can influence offspring production, and has the potential to influence how early-stage offspring (e.g., embryos) respond to moisture in their developmental environment. In this study, we use the brown anole lizard (Anolis sagrei) to examine the effects of water availability on reproductive investment. We tested the hypothesis that water available to mothers influences embryonic development under different levels of moisture in their incubation environment. We demonstrate that a substantial reduction in water availability to mothers (~70% reduction) has no observable effect on fecundity, egg size, or egg hydration. We also provide evidence that our water restriction to mothers does not influence how embryos respond to moisture conditions during egg incubation. However, moisture in the egg incubation substrate positively affected egg water uptake, egg hatching success and hatchling body size (but not hatchling hydration). Overall, our study shows that reproduction in adult female A. sagrei is robust to variation in water availability, but survival during early life stages is sensitive to this variable. Thus, the effect of water availability on different fitness components varies between life stages.

Escape responses are vital for the survival of prey. The high speeds and accelerations needed to evade predators successfully require exerting forces on the environment. Unlike water, terrestrial habitats can vary in ways that constrain the forces applied, requiring animals to adjust their behavior in response to variable conditions. We evaluated the terrestrial jumping of an amphibious fish, the blackspotted rockskipper (Entomacrodus striatus), to determine if substrate roughness and wetness influence jumping performance. We predicted that rockskippers would produce a greater force output as substrate roughness increased and wetness decreased. Using a novel waterproof force plate capable of detecting millinewton loads, we collected ground reaction forces from rockskippers jumping on wet and dry sandpapers of varying grits. We also used micro-CT scans to quantify muscle mass as a relative fraction of body mass to determine if these jumps could be performed without power amplification. Mixed-model analysis of jumps revealed significantly higher maximum horizontal forces, jump duration, and maximum power on dry versus wet substrates, but no effect of substrate roughness. However, the final jump outcomes (takeoff speed and angle) were unaffected. Peak jump power was within the range of typical fish muscle. Thus, these fish display a jumping behavior which is robust to substrate property variation.

Artificial light sources, particularly blue light, have raised concerns about their impact on biological health and behavior. In this study, we explored the effects of blue light on the locomotion and cognitive functions of early adult Drosophila melanogaster. Our experiments were conducted in a custom-designed behavioral arena to assess how blue light influences these parameters. We found that after ~2 weeks of blue light exposure, the locomotion of fruit flies, including movement speed and activity levels, significantly increased, but these effects disappeared by the third week. However, this exposure also led to a notable reduction in lifespan and had adverse effects on cognitive functions, including attention and short-term spatial memory. These findings may reveal the profound impacts of blue light on neural behavioral functions and lifespan, highlighting the importance of further research into the biological effects of blue light.

Mice in the genus Peromyscus are abundant and geographically widespread in North America, serving as reservoirs for zoonotic pathogens, including Borrelia burgdorferi (B. burgdorferi), the causative agent of Lyme disease, transmitted by Ixodes scapularis ticks. While the white-footed mouse (Peromyscus leucopus (P. leucopus)) is the primary reservoir in the United States, the deer mouse (P. maniculatus), an ecologically similar congener, rarely transmits the pathogen to biting ticks. Understanding the factors that allow these similar species to serve as a poor and competent reservoir is critical for understanding tick-borne disease ecology and epidemiology, especially as climate change expands the habitats where ticks can transmit pathogens. Our study investigated immunological differences between these rodent species. Specifically, we compared the expression of six immune genes (i.e., TLR-2, IFN-γ, IL-6, IL-10, GATA-3, TGF-β) broadly involved in bacterial recognition, elimination, and/or pathology mitigation in ear biopsies collected by the National Ecological Observatory Network (NEON) as part of their routine surveillance. A principal components analysis indicated that immune gene expression in both species varied in two dimensions: TLR2, IFN-γ, IL-6, and IL-10 (comprising PC1) and TGF-β and GATA3 (comprising PC2) expression tended to covary within individuals. However, when we analyzed expression differences of each gene singly between species, P. maniculatus expressed more TLR2, IL-6, and IL-10 but less IFN-γ and GATA3 than P. leucopus. This immune profile could partly explain why P. leucopus is a better reservoir for bacterial pathogens such as B. burgdorferi.

The open field test (OFT) is frequently used in research to assess anxiety-like behavior and locomotor activity. Its simple design can lead to the misconception that it is a standardized procedure comparable between laboratories. However, some modifications in the setup can cause changes in behavior. Different species might also react differently to the modifications introduced. There is thus need for a better understanding of the impact of modifications and their value for the species in question. Here, we tested two closely related mouse species, Mus musculus and Mus spretus, in an OFT with and without the presence of a shelter. We assessed mouse exploratory behavior through the analysis of multiple behavioral traits, and stress response through the measurement of circulating cortisol levels. Both species had elevated cortisol levels during the OFT in contrast to control animals which were not exposed to the OFT. While the presence of a shelter in the OFT increased the exploratory behavior in both mouse species, M. spretus, but not M. musculus, showed a reduction in cortisol levels. Also, other measured behaviors show a rather proactive coping strategy of the commensal M. musculus in contrast to a reactive strategy of the non-commensal M. spretus. Our study revealed a strong species-specific influence of the OFT design on the resulting behavior and stress levels of mice, illustrating the importance of OFT designs to account for the characteristics of the species under study. The addition of a shelter might be considered to improve experimental results by promoting animal welfare.