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

To overcome infection, hosts employ two defense strategies: resistance (which limits pathogen fitness), and tolerance (which reduces infection damage). These strategies may be influenced by environmental challenges such as food shortage, social conflict, and co-infections. Here, our objective was to assess defense strategies in rats infected with Trichinella spiralis and/or Trypanosoma cruzi under environmental challenges. After four weeks of treatment with environmental challenges (food restriction [0/1] and/or social conflict [0/1]), rats were exposed to Tri. spiralis [0/1] and/or Try. cruzi [0/1]. Six weeks postinoculation, we measured parasite intensity and several indicators of health or pathology. Tolerance to Try. cruzi increased in the presence of social conflict and food restriction. Coinfected animals showed reduced tolerance compared to mono-infected. However, food-restricted mono-infected rats had lower tolerance than other groups. No significant differences were found in resistance to Try. cruzi. Tolerance to Tri. spiralis was higher in food-restricted rats and Coinfected rats. Moreover, we found a potential shift in defense strategy: rats that are mono-infected and exposed to social conflict may be more resistant but less tolerant to Tri. spiralis than all other experimental groups. Overall, our findings highlight that defense strategies are context-dependent in the nematode-protozoan infection model studied, and provide evidence of a shift in the defense strategy to accommodate during environmental challenges. Given that rodents play a key role as reservoirs of zoonotic pathogens, understanding the range and variability of defense strategies in these animals is of utmost importance.

An animal's body mass is said to be indirectly related to its rate of heat loss; that is, smaller animals with higher surface area to volume tend to lose heat faster than larger animals. Thus, thermoregulation should be related to body size, however, generalizable patterns are still unclear. Domestic dogs are a diverse species of endothermic mammals, including a 44-fold difference in body size. Previous work in sedentary dogs has determined that body size and other morphological variables tend to predict the thermoregulation of exercising pet dogs. Here, we aimed to address three questions: (1) whether thermoregulatory differences in domestic dogs across seasons are dictated strictly by external environmental temperatures or if individual thermal acclimation is affected by seasonal temperature variation, even indoors; (2) whether athleticism (or training experience) affects or changes thermoregulation in dogs, as it does in humans; and (3) whether thermoregulation in domestic dogs has a genetic basis. We obtained tympanic membrane (T_ear) temperatures and thermal images to measure the rate of temperature change in the eyes, mouth, and nose of athletic dogs following an indoor agility trial. Additionally, we used image analysis to determine body morphology differences. We found body mass to play a strong role in thermoregulation in winter trials (T_mouth p = 0.017, T_nose p = 0.052) but a less determinate role in summer trials. We found distinct differences in thermoregulation patterns between winter and summer. Particularly, coat morphology and length may play different roles in thermoregulation across seasons. Additionally, we found that rates of mouth temperature change differ by an interaction between environmental temperature and training experience (p = 0.044), suggesting seasonal thermoregulation patterns in dogs depend on relative athleticism. Lastly, we found important genetic predictors of temperature change rate, such as GORAB and IGF1, as well as others that exert influence over body size, mitochondrial function, or coat characteristics. These genetic markers indicate markers similar to our whole-animal physiological results. Overall, our data suggest that domestic dogs demonstrate thermal acclimation across seasons, that athleticism changes thermoregulatory patterns in domestic dogs, and that body size-related genes are associated with thermoregulation in dogs.

Cold-water fishes, such as Brook trout (Salvelinus fontinalis), are being challenged by the consequences of climate change. The ability of these fish to acclimate to warmer environmental conditions is vital to their survival. Acclimation to warmer water may allow brook trout to reduce the metabolic costs of higher temperatures. Previous work has shown that brook trout display a significant thermal acclimation response in their myotomal muscle, with slower contractile properties observed in warm acclimated fish. In this study, gene expression was examined in hatchery brook trout acclimated to a range in temperatures (4, 10 or 20°C). Brook trout displayed variations in gene expression in their myotomal muscle in accordance with acclimation temperature. Genes important for muscle function, cellular metabolism, protein degradation, and stress response showed variation to both warm (20°C) and cold (4°C) acclimation. The warm acclimated fish also showed decreased expression of genes associated with aerobic metabolism and increased expression of genes for heat shock proteins, while the cold acclimated fish showed increased expression of genes associated with lipid metabolism and protein turnover. α-tubulin displayed a close association with thermal acclimation, increasing in expression with acclimation temperature. The patterns of muscle gene expression were the opposite of what was expected. Although warm acclimated fish have previously been shown to display slow muscle contractile properties, this study found that warm acclimation is associated with increased expression of genes for kinetically faster isoforms of important muscle proteins. Collectively, the results demonstrate a robust response to elevated temperature in the hatchery fish greater than 10,000 genes showing differential expression with temperature. These results provide a roadmap for the analysis of the acclimation response of native populations of brook trout encountering climate change.

The Atlantic Forest broad-snouted caiman (Caiman latirostris) inhabits regions within one of the world's most ecologically diverse ecosystems, yet few studies have explored the relationship between body condition, blood biochemistry, and environmental factors in the wild. Our study investigated the effects of sex, ontogeny, habitat, and environmental variables on the body condition and blood biochemistry of free-ranging caimans from the state of Alagoas, Northeast Brazil. From 2020 to 2022, we captured 75 caimans across three sites in different seasons. Results revealed sex-specific responses to seasonal and Interannual weather changes, with females showing higher body condition in the wet season, while males peaked in the dry season. Elevated glucose, total protein, albumin, triglycerides, and fructosamine were linked to higher body condition and larger individuals, while elevated aspartate aminotransferase to low body condition. Seasonal rainfall influenced blood parameters, with the dry season associated with higher creatinine, calcium, and alanine aminotransferase levels, and the wet season with higher total protein, sodium, and potassium. Differences in glucose, alkaline phosphatase, and gamma-glutamyl transferase across sites pointed to physiological effects of human activities. Blood biochemical values varied widely, with some exceeding reported species ranges. These findings highlight the need to interpret physiological data within the context of local habitat and environmental conditions. Conservation strategies should go beyond species presence and habitat preservation, incorporating pollution control. Our study advances understanding of Caiman latirostris ecophysiology, offering valuable insights for the conservation and management of crocodilian populations in both wild and captive environments.

Wound healing is a complex natural process in which tissue requires recovering injured tissue cells. Helix aspersa has a high nutritional value and is considered a rich natural source of antioxidants and anti-inflammatory agents. So, this study aimed to assess the effect of soft tissue crude extract and mucous of H. aspersa topically applied as a gel for 12 days. The wounds were observed and photographed twice a week. The inflammatory, oxidative stress markers and matrix metalloproteinases were evaluated in skin tissue homogenate and CD3⁺ and CD69⁺ T lymphocytes were detected in wound tissue. Data showed that a comparison of applying soft tissue crude extract and mucous of H. aspersa to skin wounds enhanced the healing process, resulting in a significant decrease in dermal inflammation compared to untreated mice. Also, they significantly increased the antioxidant enzyme activities with reduced malondialdehyde (MDA) levels in wound tissues. The levels of matrix metalloproteases-2 and -9 were significantly decreased and the immune status was enhanced in the wound environment by increasing proportions of CD3⁺ and CD69⁺ T lymphocytes. H. aspersa mucous and soft tissue crude extract are viable substitutes for synthetic topical wound therapies with anti-inflammatory, antioxidant, and immunomodulatory potencies, with a preference for the crude soft tissue extract based on the outcomes.

One neglected zoonotic illness is toxocariasis. There are not enough anthelmintic drugs in the market to treat low-effectiveness toxocariasis against migrating larvae. Therefore, it is critical to find new, safe alternatives to toxocariasis treatment today. The venom of the Leiurus quinquestratus scorpion (LQV) has numerous medicinal uses. The purpose of this study was to conduct that LQV had an effect on T. canis larvae in the model of mice. Fifty male mice were divided into five groups (n = 10). Group 1 (Gp1) was the negative group, and from Gp2-Gp5 had been infected with 800-1000 T. canis embryonated eggs. Gp2 was left as positive control, Gp3 was orally administrated with albendazole (Alb) (100 mg/kg/b.wt) for 7 consecutive days at first day post infection (pi), Gp4 was injected intra-peritoneal (i.p) with LQV (0.03 mg/kg/b.wt) for 15 consecutive days at the first day pi, and Gp5 was given Alb/LQV in the same way and doses as Gp3 and Gp4. At the end of the experiment, at 30th pi, the blood samples were collected for evaluating the biochemical and hematological parameters. The larval count reduction in brain were evaluated, and the histopathological changes in brain and liver were detected. The results showed that, treatment with LQV or Alb/LQV combinations significantly reduced the larval burden in the brain of the infected mice with reduction percentage reached to 70, and 72%, respectively. Interestingly, LQV and Alb/LQV significantly reduced IL-4, IL-10, and TNF -α levels and increased IFN-γ levels. Also, improved the liver transaminases activity, and ameliorated liver and brain architecture. Collectively, LQV may be a promising treatment for T. canis infection and albendazole alternative.

In euryhaline teleosts, the cystic fibrosis transmembrane conductance regulator (CFTR) in seawater (SW)-type chloride cells facilitates apical Cl^- secretion for SW adaptation, while alternative Cl^- excretion pathways remain understudied. This study investigates the role of the calcium-activated chloride channel, Anoctamin 1 (ANO1), in the gills of the euryhaline Japanese medaka (Oryzias latipes) under hyperosmolality and cortisol (CORT) influence. Acclimation to artificial SW, NaCl, mannitol, or glucose significantly upregulated ANO1 and CFTR mRNA expression in gills, unlike urea treatment. In situ hybridization revealed ANO1 mRNA in chloride cells co-expressing CFTR and Na⁺, K⁺-ATPase under hyperosmotic conditions. ANO1 inhibition elevated plasma Cl^- concentration, indicating impaired Cl^- excretion. CORT or dexamethasone administration in freshwater (FW) fish significantly increased branchial ANO1 and CFTR mRNA expression, an effect attenuated by the glucocorticoid receptor (GR) antagonist RU486. Hyperosmotic treatment of isolated gill tissues rapidly induced ANO1 mRNA expression independent of CFTR mRNA changes, and this induction was unaffected by RU486. These findings highlight the dual regulation of ANO1 expression via hyperosmolality-induced cellular response and the CORT-GR system. Thus, branchial ANO1 may likely complement CFTR in Cl⁻ excretion, playing a key role in the hyperosmotic adaptation of euryhaline teleosts.

Food availability shapes morphology, physiology, growth, reproduction, and overall fitness of insects. Countless research in coccinellids reported the effect of diet in terms of quality and quantity on reproductive output. But fewer studies have reported the direct effects of food on the gonadal development in both sexes. In nature, ladybird beetle Cheilomenes sexmaculata exhibit food preference, favouring Aphis craccivora (nutritious prey) over Aphis nerii (poor prey). We hypothesized that beetles consuming nutritious prey in abundant quantity will have larger and heavier gonads. The current study assessed the effect of food preferred and its fluctuations on the gonadal development of C. sexmaculata. First instars were collected randomly from experimental stock and reared on two different diet regimes for a lifetime. After eclosion, beetles from each dietary regime were dissected daily to assess gonadal development until maturity. Here, we documented total developmental duration, body weight, weight of gonads, GSI, total area of gonads, length, and number of testicular lobules/ovarioles across different treatments. Both quality and quantity of diet significantly affected development period, body weight, and gonadal parameters in both sexes except for GSI in males and number of ovarioles in females that reared on varied diet quality, which were found to be similar. Aphis craccivora in abundant supply positively affected the growth and development of the gonads in C. sexmaculata. Beetles reared on the abundant supply of nutritious prey with larger and heavier gonads than those reared on limited supply or poor prey. This study improves our understanding of the development of gonads in ladybird beetles, which may be helpful in improving the mass rearing of ladybird beetles.

Many songbirds begin active incubation after laying their penultimate egg, resulting in synchronous hatching of the clutch except for a last-hatched individual ("runt") that hatches with a size deficit and competitive disadvantage to siblings when begging for food. However, climate change may elevate temperatures and cause environmental incubation as eggs are laid, resulting in asynchronous hatching and larger size hierarchies among siblings. Although previous work demonstrated that asynchronous hatching reduces nestling growth and survival relative to synchrony, the physiological mechanisms underlying these effects are unclear. To test the effects of asynchronous hatching on runt growth, survival, physiology, and compensatory growth-related tradeoffs, we manipulated incubation temperature in nest boxes of European starlings (Sturnus vulgaris) to increase asynchronous hatching and collected nestling morphological measurements and blood samples to assess physiology and development. Independent of heating treatment, runts from asynchronously hatched nests had lower survival than runts from more synchronous nests. Surviving runts from asynchronous nests were smaller and had reduced stress-induced corticosterone concentrations and reduced circulating glucose compared with runts from synchronous nests. Despite persistent size and energy deficits, runts from asynchronous nests did not have significant deficits in immunity or telomere length when compared with runts from synchronous nests, suggesting no trade-off between investment in immune development or telomere maintenance with growth. Overall, these results suggest that increased asynchrony due to climate change could reduce clutch survival for altricial songbirds, especially for the smallest chicks in a clutch, and that the negative effects of asynchrony may be driven by persistent energetic deficits.