Preparation for oxidative stress in Chinese toads (Bufo gargarizans) living under natural conditions along an altitudinal gradient

Preparation for oxidative stress (POS) has been widely reported in animals under controlled laboratory conditions, but whether this phenomenon is visible in animals under natural conditions remains to be explored. Altitudinal gradients provide a good opportunity to address this question, since environmental conditions become more hostile with increasing altitude. Here, we investigated the levels of oxidative stress, oxidative damage, and antioxidant defenses in Chinese toads (Bufo gargarizans) along an altitudinal gradient (50 m, 1200 m, 2300 m, 3400 m above sea level). The results show that changing altitude led to a significantly lower ratio of oxidized to reduced glutathione in liver, with a higher value at 50 m. This ratio in muscle tissues did not differ significantly between altitudes of 50 m, 2300 m, and 3400 m. However, reduced glutathione content increased significantly along the altitude, with higher values in liver at 2300 m and higher values in skeletal muscle at 3400 m. Malondialdehyde (MDA) content in liver did not change significantly with increasing altitude. Brain and muscle tissues showed a higher MDA content at 50 m than the other three altitudes. The activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase, as well as total antioxidant capacity, also displayed tissue-specific upregulation in heart, skeletal muscle, and brain, but all of these antioxidant enzymes except for glutathione-S-transferase were significantly reduced in liver along the altitudinal gradient. In summary, environmental factors at higher altitude did not lead to higher levels of oxidative stress and oxidative damage in B. gargarizans, mainly due to stronger antioxidant defenses. This study corroborates the occurrence of POS in high-altitude toads living under field conditions and contributes to revealing the biochemical adaptations to extreme environments at higher altitude.

Effects of herbal formula on growth performance, apparent digestibility, antioxidant capacity, and rumen microbiome in fattening lambs under heat stress

Heat stress (HS) causes severe economic losses in sheep industry worldwide. The objective of the present study was to investigate the effects of a herbal formula (HF) supplement on growth, digestibility, antioxidant capacity, and rumen microbes in fattening lambs under HS. The HF composed of four herbs was prepared based on the theory of compatibility of Chinese medicine "Jun-Chen-Zuo-Shi". Two-hundred forty 3-month weaned lambs (initial weight 36.61 ± 0.73 kg) were randomly allocated into four groups, supplemented 0% (Control), 0.5%, 1.0%, and 1.5% HF in diets. All lambs were exposed to HS conditions with 79.7 of average temperature-humidity index throughout an experimental period of 35 days. Growth performance, apparent digestibility, and antioxidant activities, involving antioxidant enzymes and heat shock proteins (HSPs), were measured at the end of trial, as well as microbial communities in bacteria and archaea. Results showed that 0.5% HF increased (P = 0.02) average daily gain by 13.80% and decreased feed-to-gain ratio (P = 0.03) by 14.68%, compared to control. With increasing HF doses, the digestibility of ether extract and acid detergent fiber demonstrated a cubical (P < 0.01) and quadratic (P = 0.03) relation, respectively; moreover, glutathione peroxidase and catalase activities demonstrated a quadratic increase (P < 0.01). Serum levels of HSP60, HSP70, and HSP90 for 0.5% HF were lower than that in control (P < 0.05). On the other hand, total volatile fatty acid, acetic acid, butyric acid, valeric acid, and isovaleric acid levels exhibited quadratic increases (P ≤ 0.01) with HF doses. From rumen microbes, the abundance and diversity of bacterial community were improved by HF supplements. Particularly for 0.5% HF group, the operational taxonomic units were the greatest among all groups. Compared to control, Prevotella abundance for HF supplements from 0.5 to 1.5% increased by 35.57 to 60.15%, and Succiniclasticum abundance demonstrated a quadratic pattern (P = 0.02) with doses. Additionally, Methanosphaera abundance in archaeal community raised by 0.2 to 3.3-folds when lambs were fed the HF additions of 0.5 to 1.5%. In summary, dietary HF supplements would contribute to alleviating HS in lambs, and our results suggest the optimal dose of 0.5% HF supplement in diet.

Protective effects of butyric acid during heat stress on the survival, immune response, histopathology, and gene expression in the hepatopancreas of juvenile pacific shrimp (L. Vannamei)

This study looked at the effects of adding butyric acid (BA) to the diets of juvenile Pacific shrimp and how it affected their response to survival, immunity, histopathological, and gene expression profiles under heat stress. The shrimp were divided into groups: a control group with no BA supplementation and groups with BA inclusion levels of 0.5 %, 1 %, 1.5 %, 2 %, and 2.5 %. Following the 8-week feeding trial period, the shrimp endured a heat stress test lasting 1 h at a temperature of 38 °C. The results showed that the control group had a lower survival rate than those given BA. Interestingly, no mortality was observed in the group receiving 1.5 % BA supplementation. Heat stress had a negative impact on the activities of alkaline phosphatase (AKP) and acid phosphatase (ACP) in the control group. Still, these activities were increased in shrimp fed the BA diet. Similar variations were observed in AST and ALT fluctuations among the different groups. The levels of triglycerides (TG) and cholesterol (CHO) increased with high temperatures but were reduced in shrimp-supplemented BA. The activity of an antioxidant enzyme superoxide dismutase (SOD) increased with higher BA levels (P < 0.05). Moreover, the groups supplemented with 1.5 % BA exhibited a significant reduction in malondialdehyde (MDA) content (P < 0.05), suggesting the potential antioxidant properties of BA. The histology of the shrimp's hepatopancreas showed improvements in the groups given BA. Conversely, the BA significantly down-regulated the HSPs and up-regulated MnSOD transcript level in response to heat stress. The measured parameters determine the essential dietary requirement of BA for shrimp. Based on the results, the optimal level of BA for survival, antioxidant function, and immunity for shrimp under heat stress is 1.5 %.

Impact of rising temperature on physiological and biochemical alterations that affect the viability of blood cells in American bullfrog crossbreeds

The study aimed to examine the impact of increasing environmental temperatures on physiological changes, oxidative stress, nitric oxide production, total antioxidant capacity, and blood cell viability in American bullfrog crossbreeds. Frogs and frog blood cells were exposed to temperature ranges of 25-33 °C and 25-37 °C, respectively. Physiological parameters (body temperature, pulse rate, ventilation rate, and oxygen saturation) and biochemical parameters (total antioxidant power, hydrogen peroxide, malondialdehyde, nitric oxide, and mitochondrial activity) were measured at every 2 °C increment. Results showed that body temperature rose with increased environmental temperature (P < 0.05). Pulse rates at 33 °C were higher than those at 25-31 °C (P < 0.05). Ventilation rates at 31 °C exceeded those at 25 °C and 27 °C (P < 0.05). Oxygen saturation levels remained stable at 25-33 °C (P > 0.05). Total antioxidant power at 25 °C was greater than at 27-37 °C (P < 0.05). Hydrogen peroxide levels at 27 °C were higher compared to 25 °C and 31-37 °C (P < 0.05). Malondialdehyde levels at 25-33 °C were higher than at 35 °C and 37 °C (P < 0.05). Nitric oxide levels at 37 °C were higher than at 25-33 °C (P < 0.05), and at 35 °C were higher than at 25-31 °C (P < 0.05). Blood cell viability at 25-31 °C was higher than at 37 °C (P < 0.05). These results suggest that at an environmental temperature of 33 °C, the frogs' body temperature approached 31 °C or higher, and were likely to be harmful to the frogs. Finally, the environmental temperature that caused frog blood cell death was 37 °C.

Effects of thermal stress responses in goldfish (Carassius auratus): growth performance, total carotenoids and coloration, hematology, liver histology, and critical thermal maximum

The present study aimed to investigate the effect of thermal stress on growth, feed utilization, coloration, hematology, liver histology, and critical thermal maximum (CTmax) in goldfish (Carassius auratus) cultured at three different acclimation temperatures including 27 °C, 30 °C, and 34 °C for 10 weeks. Goldfish were assigned randomly to tanks with a quadruplicate setup, accommodating 20 fish per tank. The result showed that fish acclimated to different temperatures did not significantly differ in weight gain (WG) and specific growth rate (SGR). However, increasing temperature significantly decreased feed efficiency ratio (FER), protein efficiency ratio (PER), and protein productive value (PPV), but significantly increased feed conversion ratio (FCR) (P < 0.05). The coloration parameters significantly decreased by high temperature in the trunk region with increasing temperature (L* and a* at week 5; L*, a*, and b* at week 10; P < 0.05). Total carotenoid contents in serum, fin, muscle, and skin also significantly decreased with increasing temperature (P < 0.05). Total protein, albumin, and globulin levels exhibited a notable decrease, while the albumin: globulin ratio showed a slight insignificant increase, with increasing temperature. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total cholesterol, and triglycerides significantly increased with increasing temperature (P < 0.05). While, high-density lipoprotein cholesterol (HDL-c) decreased linearly (P < 0.05). Glucose and cortisol levels linearly increased with increasing temperature, the highest levels being observed in the 34 °C group. Liver histology showed swollen hepatocytes, nuclei displacement, and infiltration of inflammation in fish cultured at 34 °C. Goldfish acclimated to 34 °C displayed a higher CTmax of 43.83 °C compared to other groups. The present study showed that temperature should be kept below 34 °C for goldfish culture to prevent high FCR, fading coloration, and liver damages.

How Does Mitochondrial Protein-Coding Gene Expression in Fejervarya kawamurai (Anura: Dicroglossidae) Respond to Extreme Temperatures?

Unusual climates can lead to extreme temperatures. Fejervarya kawamurai, one of the most prevalent anurans in the paddy fields of tropical and subtropical regions in Asia, is sensitive to climate change. The present study focuses primarily on a single question: how do the 13 mitochondrial protein-coding genes (PCGs) respond to extreme temperature change compared with 25 °C controls? Thirty-eight genes including an extra tRNA-Met gene were identified and sequenced from the mitochondrial genome of F. kawamurai. Evolutionary relationships were assessed within the Dicroglossidae and showed that Dicroglossinae is monophyletic and F. kawamurai is a sister group to the clade of (F. multistriata + F. limnocharis). Transcript levels of mitochondrial genes in liver were also evaluated to assess responses to 24 h exposure to low (2 °C and 4 °C) or high (40 °C) temperatures. Under 2 °C, seven genes showed significant changes in liver transcript levels, among which transcript levels of ATP8, ND1, ND2, ND3, ND4, and Cytb increased, respectively, and ND5 decreased. However, exposure to 4 °C for 24 h was very different in that the expressions of ten mitochondrial protein-coding genes, except ND1, ND3, and Cytb, were significantly downregulated. Among them, the transcript level of ND5 was most significantly downregulated, decreasing by 0.28-fold. Exposure to a hot environment at 40 °C for 24 h resulted in a marked difference in transcript responses with strong upregulation of eight genes, ranging from a 1.52-fold increase in ND4L to a 2.18-fold rise in Cytb transcript levels, although COI and ND5 were reduced to 0.56 and 0.67, respectively, compared with the controls. Overall, these results suggest that at 4 °C, F. kawamurai appears to have entered a hypometabolic state of hibernation, whereas its mitochondrial oxidative phosphorylation was affected at both 2 °C and 40 °C. The majority of mitochondrial PCGs exhibited substantial changes at all three temperatures, indicating that frogs such as F. kawamurai that inhabit tropical or subtropical regions are susceptible to ambient temperature changes and can quickly employ compensating adjustments to proteins involved in the mitochondrial electron transport chain.

Potential Effects of High Temperature and Heat Wave on Nanorana pleskei Based on Transcriptomic Analysis

In the context of climate change, understanding how indigenous amphibians of the Qinghai-Tibet plateau react to stresses and their coping mechanisms could be crucial for predicting their fate and successful conservation. A liver transcriptome for Nanorana pleskei was constructed using high-throughput RNA sequencing, and its gene expression was compared with frogs acclimated under either room temperature or high temperature and also heat wave exposed ones. A total of 126,465 unigenes were produced, with 66,924 (52.92%) of them being annotated. Up to 694 genes were found to be differently regulated as a result of abnormal temperature acclimatization. Notably, genes belonging to the heat shock protein (HSP) family were down-regulated in both treated groups. Long-term exposure to high-temperature stress may impair the metabolic rate of the frog and trigger the body to maintain a hypometabolic state in an effort to survive challenging times. During heat waves, unlike the high-temperature group, mitochondrial function was not impaired, and the energy supply was largely normal to support the highly energy-consuming metabolic processes. Genes were more transcriptionally suppressed when treated with high temperatures than heat waves, and the body stayed in low-energy states for combating these long-term adverse environments to survive. It might be strategic to preserve initiation to executive protein activity under heat wave stress. Under both stress conditions, compromising the protection of HSP and sluggish steroid activity occurred in frogs. Frogs were more affected by high temperatures than by heat waves.

Comparative study on the effects of crystalline L-methionine and methionine hydroxy analogue calcium supplementations in the diet of juvenile Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted to evaluate the effects of L-methionine and methionine hydroxy analogue calcium (MHA-Ca) supplements in low-fishmeal diet on growth performance, hepatopancreas morphology, protein metabolism, anti-oxidative capacity, and immunity of Pacific white shrimp (Litopena eus vannamei). Four isonitrogenous and isoenergetic diets were designed: PC (203.3 g/kg fishmeal), NC (100 g/kg fishmeal), MET (100 g/kg fishmeal +3 g/kg L-methionine) and MHA-Ca (100 g/kg fishmeal +3 g/kg MHA-Ca). White shrimp (initial body weight 0.23 ± 0.00 g, 50 shrimp per tank) were allocated to 12 tanks and divided among 4 treatments in triplicates. In response to L-methionine and MHA-Ca supplementations, the shrimp exhibited higher weight gain rate (WGR), specific growth rate (SGR), condition factor (CF), and lower hepatosomatic index (HSI) compared to those fed the NC diet (p < 0.05). The WGR and SGR of shrimp fed L-methionine and MHA-Ca showed no difference with those in the PC diet (p > 0.05). Both of L-methionine and MHA-Ca supplementary diets significantly decreased the malondialdehyde (MDA) levels of shrimp when compared with the NC diet (p < 0.05). L-methionine supplementation improved the lysozyme (LZM) activity and total antioxidant capacity (T-AOC) of shrimp, while the MHA-Ca addition elevated the reduced glutathione (GSH) levels in comparison with those fed the NC diet (p < 0.05). Hypertrophied blister cells in hepatocytes were observed in shrimp fed the NC diet, and alleviated with L-methionine and MHA-Ca supplementations. Shrimp fed the MET and MHA-Ca diets had higher mRNA expression levels of target of rapamycin (tor) than those fed the NC diet (p < 0.05). Compared to the NC group, dietary MHA-Ca supplementation upregulated the expression level of cysteine dioxygenase (cdo) (p < 0.05), while L-methionine supplementation had no significant impact (p > 0.05). The expression levels of superoxide dismutase (sod) and glutathione peroxidase (gpx) were significantly upregulated by L-methionine supplemented diet in comparison with those in the NC group (p < 0.05). Overall, the addition of both L-methionine and MHA-Ca elevated the growth performance, facilitated protein synthesis, and ameliorated hepatopancreatic damage induced by plant-protein enriched diet in L. vannamei. L-methionine and MHA-Ca supplements enhanced anti-oxidants differently.

Appropriate cold stimulation changes energy distribution to improve stress resistance in broilers

Appropriate cold stimulation can improve stress resistance in broilers and alleviate the adverse impacts of a cold environment. To investigate the effects of intermittent mild cold stimulation (IMCS) on energy distribution in the livers of broilers, 96 healthy 1-d-old Ross-308 male broilers were randomly divided into the control group (CC) and the cold stimulation group (H5). The CC group was raised at a normal thermal temperature, i.e., 35 °C until 3 d, after which the temperature was dropped gradually by 0.5 °C/d until 20 °C at 33 d. This temperature was maintained until 49 d. The H5 group was raised at the same temperature as the CC group until 14 d (35 to 29.5 °C) and at 3 °C below the temperature of the CC group starting at 0930 hours for 5 h every other day from 15 to 35 d (26 to 17°C). The temperature was returned to 20 °C at 36 d and maintained until 49 d. At 50 d, all broilers were subjected to acute cold stress (ACS) at 10 °C for 6 and 12 h. We found that IMCS had positive effects on production performance. Using transcriptome sequencing of the broiler livers, 327 differentially expressed genes (DEG) were identified, and highly enriched in fatty acid biosynthesis, fatty acid degradation, and the pyruvate metabolism pathway. When compared to the CC group, the mRNA levels of ACAA1, ACAT2, ACSL1, CPT1A, LDHB, and PCK1 in the H5 group were increased at 22 d (P < 0.05). The LDHB mRNA level was upregulated in the H5 group at 29 d compared to the CC group (P < 0.05). After 21 d of IMCS (at 36 d), the mRNA expression levels of ACAT2 and PCK1 were found to be significantly increased in the H5 group compared to the CC group (P < 0.05). Seven days after the IMCS had ended (at 43 d), the mRNA levels of ACAA1, ACAT2, and LDHB in the H5 group were higher than in the CC group (P < 0.05). The mRNA levels of heat shock protein (HSP) 70, HSP90, and HSP110 in the H5 group were higher than in the CC group after 6 h of ACS (P < 0.05). The protein levels of HSP70 and HSP90 in the H5 group were downregulated after 12 h of ACS, compared to the CC group (P < 0.05). These results indicated that IMCS at 3 °C lower than the normal temperature could improve energy metabolism and stress resistance in the livers of broilers, alleviate the damage of short-term ACS on broilers, help broilers adapt to the low temperature, and maintain stable of energy metabolism in the body.

Dietary nanoselenium supplementation for heat-stressed rainbow trout: effects on organizational structure, lipid changes, and biochemical parameters as well as heat-shock-protein- and selenoprotein-related gene expression

Nanoselenium (nano-Se) shows unique protective effects against environmental heat stress in rainbow trout as a selenium source additive and free radical scavenger. Accordingly, we investigated the effects of supplementation with different levels of nano-Se (0, 5, and 10 mg/kg) and before and after heat stress (24°C) for different treatment times on the dynamic changes of rainbow trout liver tissue structure, lipid changes, biochemical properties, and gene expression. The results showed that, under heat stress, the fish supplementation of 5 mg/kg nano-Se significantly increased liver glutathione peroxidase (GPx) activity and upregulated expression levels of HSP70b, HSP90a1, GPx1a, and Trx mRNAs, while liver alanine aminotransferase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), and malondialdehyde (MDA) levels as well as tissue structure damage and lipid accumulation were decreased. Combining the trends for the above indicators indicated that stress began to increase significantly at 8 h. It can be concluded that supplementation with 5 mg/kg nano-Se effectively alleviates stress damage in rainbow trout. Furthermore, stress at 24°C for 8 h can be thought of as a critical time point for the study of heat stress in rainbow trout, with significant changes in response but no serious damage. Thus, these results provide a reference for the addition of nano-Se to rainbow trout feed and provide theoretical and practical guidance for enhancing the resistance of rainbow trout to heat stress.

Rates of warming impact oxidative stress in zebrafish (Danio rerio)

Potentially negative effects of thermal variation on physiological functions may be modulated by compensatory responses, but their efficacy depends on the timescale of phenotypic adjustment relative to the rate of temperature change. Increasing temperatures in particular can affect mitochondrial bioenergetics and rates of reactive oxygen species (ROS) production. Our aim was to test whether different rates of temperature increase impact mitochondrial bioenergetics and modulate oxidative stress. We exposed zebrafish (Danio rerio) to warming from 20 to 28°C over 3, 6, 24, or 48 h, and compared these to a control group that was kept at constant 20°C. Fish exposed to the fastest (3 h) and slowest (48 h) rates of warming had significantly higher rates of H2O2 production relative to the control treatment, and the proportion of O2 converted to H2O2 (H2O2/O2 ratio) was significantly greater in these groups. However, ROS production was not paralleled by differences in mitochondrial substrate oxidation rates, leak respiration rates, or coupling (respiratory control ratios). Increased rates of ROS production did not lead to damage of proteins or membranes, which may be explained by a moderate increase in catalase activity at the fastest, but not the slowest rate of warming. The increase in ROS production at the slowest rate of heating indicates that even seemingly benign environments may be stressful. Understanding how animals respond to different rates of temperature change is important, because the rate determines the time period for phenotypic adjustments and it also alters the environmental thermal signal that triggers compensatory pathways.

Influence of High Temperatures and Heat Wave on Thermal Biology, Locomotor Performance, and Antioxidant System of High-Altitude Frog Nanorana pleskei Endemic to Qinghai-Tibet Plateau

Investigating how highland amphibians respond to changes in ambient temperature may be of great significance for their fate prediction and effective conservation in the background of global warming. Here, using field individuals as the control group, we investigated the influence of high temperatures (20.5 and 25.5°C) and heat wave (15–26.6°C) on the thermal preference, critical thermal limits, locomotor performance, oxidative stress, and antioxidant enzyme activities in high-altitude frog Nanorana pleskei (3,490 m) endemic to the Qinghai-Tibet Plateau (QTP). After 2 weeks of acclimation to high temperatures and heat wave, the thermal preference (Tpref), critical thermal maximum (CTmax), and range of tolerable temperature significantly increased, while the critical thermal minimum (CTmin) was significantly decreased. The total time of jump to exhaustion significantly decreased, and burst swimming speed significantly increased in frogs acclimated in the high temperature and heat wave groups compared with the field group. In the high temperature group, the level of H2O2 and lipid peroxide (malondialdehyde, MDA), as well as the activities of glutathione peroxidase (GPX), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) significantly increased in the liver or muscle. However, in the heat wave group, the MDA content significantly decreased in the liver, and antioxidants activities decreased in the liver and muscle except for CAT activities that were significantly increased in the liver. These results indicated that N. pleskei could respond to the oxidative stress caused by high temperatures by enhancing the activity of antioxidant enzymes. The heat wave did not appear to cause oxidative damage in N. pleskei, which may be attributed to the fact that they have successfully adapted to the dramatic temperature fluctuations on the QTP.

Plasticity of Performance Curves in Ectotherms: Individual Variation Modulates Population Responses to Environmental Change

Many ectothermic animals can respond to changes in their environment by altering the sensitivities of physiological rates, given sufficient time to do so. In other words, thermal acclimation and developmental plasticity can shift thermal performance curves so that performance may be completely or partially buffered against the effects of environmental temperature changes. Plastic responses can thereby increase the resilience to temperature change. However, there may be pronounced differences between individuals in their capacity for plasticity, and these differences are not necessarily reflected in population means. In a bet-hedging strategy, only a subsection of the population may persist under environmental conditions that favour either plasticity or fixed phenotypes. Thus, experimental approaches that measure means across individuals can not necessarily predict population responses to temperature change. Here, we collated published data of 608 mosquitofish (Gambusia holbrooki) each acclimated twice, to a cool and a warm temperature in random order, to model how diversity in individual capacity for plasticity can affect populations under different temperature regimes. The persistence of both plastic and fixed phenotypes indicates that on average, neither phenotype is selectively more advantageous. Fish with low acclimation capacity had greater maximal swimming performance in warm conditions, but their performance decreased to a greater extent with decreasing temperature in variable environments. In contrast, the performance of fish with high acclimation capacity decreased to a lesser extent with a decrease in temperature. Hence, even though fish with low acclimation capacity had greater maximal performance, high acclimation capacity may be advantageous when ecologically relevant behaviour requires submaximal locomotor performance. Trade-offs, developmental effects and the advantages of plastic phenotypes together are likely to explain the observed population variation.

Effects of temperature on growth, development and the leptin signaling pathway of Bufo gargarizans

Climate change is one of the most important causes of the decline in amphibians. Changes in temperature have an important effect on the growth and development and energy metabolism of amphibians. The aim of this study is to unravel the effects of temperature on the leptin signaling pathway of Bufo gargarizans and its molecular mechanisms. Our results showed that high temperature accelerated the development rate of tadpoles, but reduced body size and mass, while low temperature deferred the development of tadpoles, but increased size and mass. Both high temperature and low temperature exposure caused pathological damage of the liver in B. gargarizans. The results of RT-qPCR revealed that the high temperature treatment significantly upregulated the transcript levels of genes related to thyroid hormone (DIO2 (D2), Thyroid Hormone Receptor-α (TRα)) and the leptin signaling pathway (Leptin Receptor (LepR), Janus kinase 1 (JAK1), Janus kinase 2 (JAK2), Tyrosine kinase 2 (TYK2), Signal Transducer And Activator Of Transcription 3 (STAT3), Signal Transducer And Activator Of Transcription 3.1 (STAT3.1), and Signal Transducer And Activator Of Transcription 6 (STAT6)), while there was a decrease of mRNA expression of these genes (TRα, Thyroid Hormone Receptor-Beta (TRβ), LepR, JAK1, and TYK2) in the liver of tadpoles exposed to high temperature compared with the intermediate temperature treatment. Therefore, our results suggested that temperature extremes might interfere with the thyroid and leptin signaling pathways and affect the growth and development of B. gargarizans. Furthermore, tissue injury of the liver could occur due to exposure to temperature extremes. This work promotes public awareness of environmental protection and species conservation needs, also provides valuable experimental data and a theoretical basis for the protection of amphibians.

Functional differences of three CXCL10 homologues in the giant spiny frog Quasipaa spinosa

Chemokines are a superfamily of structurally related chemotactic cytokines exerting significant roles in acting as a bridge between the innate and adaptive immune responses. In this study, we identified three CXC motif chemokine 10 (CXCL10) homologues (QsCXCL10-1, QsCXCL10-2 and QsCXCL10-3) from giant spiny frog Quasipaa spinosa. All three deduced QsCXCL10 proteins contained four conserved cysteine residues as found in other known CXC chemokines. Phylogenetic analysis showed that QsCXCL10-1, 2, 3 and other CXCL10s in amphibian were grouped together to form a separate clade. These three QsCXCL10s were highly expressed in spleen and blood. Upon infection with Staphylococcus aureus or Aeromonas hydrophila, the expressions of QsCXCL10s were markedly increased in spleen and blood during biotic stresses. Meanwhile, the QsCXCL10s transcription in liver could also be up-regulated under abiotic stresses such as cold and heat stresses. The recombinant proteins of frog CXCL10 homologues were produced and purified in E. coli and possessed similar but differential bioactivities. Both rCXCL10-1 and rCXCL10-2 had strong effects on the up-regulation of pro-inflammatory cytokines (TNF-α, IL-1β and IL-8) in vivo, whereas rCXCL10-3 induced a weak expression of these cytokines. Moreover, the rCXCL10-1 and rCXCL10-2 could strongly promote splenocyte proliferation and induce lymphocytes migration, while rCXCL10-3 had limited effects on these biological processes. All three frog chemokines triggered their functional activities by engaging CXC motif chemokine receptor 3 (CXCR3). Taken together, these results revealed that the three QsCXCL10s had similar but differential functional activities in mediating immune responses and host defenses, which might contribute to a better understanding of the functional evolution of CXCL10 in vertebrates.

Transcriptome changes of Takifugu obscurus liver after acute exposure to the oxygenated-PAH 9,10-phenanthrenequione

Contamination with polycyclic aromatic hydrocarbons (PAHs) causes noticeable ecological problems in aquatic ecosystems. 9,10-Phenanthrenequione (9,10-PQ) is an oxidized PAH and is highly toxic to aquatic animals. However, the effects of 9,10-PQ on the molecular metabolism of fish remain largely unknown. In this study, Takifugu obscurus juveniles were acutely exposed to 44.30 µg/L 9,10-PQ for 3 days. The transcriptome profile changes in their livers were compared between the 9,10-PQ treatment group and the control using T. rubripes as the reference genome. The results identified 22,414 genes in our transcriptome. Among them, 767 genes were differentially expressed after exposure to 9,10-PQ, which enriched 16 KEGG pathways. Among them, the glycolysis, phagosome, and FOXO signaling pathways were significantly activated in 9,10-PQ treatment compared with the control. These data indicate that 9,10-PQ increased the glycolysis capacity to produce more energy for resistance and harmed immune function. Moreover, several genes related to tumorigenesis were significantly upregulated in response to 9,10-PQ, displaying the carcinogenic toxicity of 9,10-PQ to T. obscurus. Genes in steroid biosynthesis pathways were downregulated in the 9,10-PQ treatment group, suggesting interference with the endocrine system. Overall, these findings provide information to help evaluate the environmental risks that oxygenated-PAHs present to T. obscurus.

HSP70 localization in Podarcissiculus embryos under natural thermal regime and following a non-lethal cold shock

The Heat Shock Proteins (HSPs) are a superfamily of molecular chaperones that maintain cellular homeostasis under stress. HSP70 represents the major stress-inducible family member, often activated in response to changes in thermal ranges of organisms, and therefore playing an important role enhancing thermal tolerance limits in ectothermic animals. The present study aimed to investigate the presence and the localization of HSP70 through the development of Podarcis siculus, an oviparous lizard inhabiting temperate Mediterranean regions, showing a limited potential to tolerate thermal changes during embryogenesis. Immunohistochemical analysis demonstrated that HSP70 protein is constitutively present in early embryonic stages, abundantly distributed in eye, in encephalic domains (predominantly in ventricular areas and in grey matter), in grey matter of spinal cord, in lung, gut mucosa, hepatic cords and kidney tubules. Interestingly, a severe drop in incubation temperature (5°C for 3 days) does not induce enhancements in HSP70 levels nor changes in tissues localization. These results suggest that the HSP70 found in P. siculus embryos represents a non-inducible, constitutive molecular chaperone that should be better called Heat Shock Cognate 70 (HSC70); the presence of stress-induced members of the HSP family in P. siculus has yet to be proven.

Heat Waves, the New Normal: Summertime Temperature Extremes Will Impact Animals, Ecosystems, and Human Communities

A consequence of climate change is the increased frequency and severity of extreme heat waves. This is occurring now as most of the warmest summers and most intense heat waves ever recorded have been during the past decade. In this review, I describe the ways in which animals and human populations are likely to respond to increased extreme heat, suggest how to study those responses, and reflect on the importance of those studies for countering the devastating impacts of climate change.