Acclimation Temperature Research Articles

Biomethane potential test applied to psychrophilic conditions: Three issues about inoculum temperature adaptation

This study aimed to give lights for establishing a psychrophilic BMP test by three approaches for inoculum acclimation under 25 °C. The first test was run using stabilized mesophilic (25 °C) and psychrophilic (15 °C) inoculums to digest cellulose. Second was based on temperature acclimatization of inoculum just by time, from 30 to 10 and 20 °C. The third was running a consecutive BMP under psychrophilic temperatures (23 °C). Cellulose psychrophilic BMP using stabilized psychrophilic inoculum achieve similar results to those obtained at mesophilic conditions with stabilized mesophilic inoculum. Time acclimatization of inoculum improve BMP results respect non-adapted (from 0.47 to 055 Nm3 CH4 kg−1 SV at 20 °C, from 0.31 to 0.44 Nm3 CH4 kg−1 SV at 10 °C). Consecutive BMP under psychrophilic conditions shows better results for inoculum acclimatization to run assays at low temperatures. There is a need to develop and standardize a procedure to run psychrophilic BMP.

There and back again: A meta-analytical approach on the influence of acclimation and altitude in the upper thermal tolerance of amphibians and reptiles

Realistic predictions about the impacts of climate change onbiodiversity requires gathering ecophysiological data and the critical thermal maxima (CTMax) is the most frequently used index to assess the thermal vulnerability of species. In the present study, we performed a systematic review to understand how acclimation and altitude affect CTMax estimates for amphibian and non-avian reptile species. We retrieved CTMax data for anurans, salamanders, lizards, snakes, and turtles/terrapins. Data allowed to perform a multilevel random effects meta-analysis to answer how acclimation temperature affect CTMax of Anura, Caudata, and Squamata and also meta-regressions to assess the influence of altitude on CTMax of frogs and lizards. Acclimation temperature influenced CTMax estimates of tadpoles, adult anurans, salamanders, and lizards, but not of froglets. In general, the increase in acclimation temperature led to higher CTMax values. Altitudinal bioclimatic gradient had an inverse effect for estimating the CTMax of lizards and anuran amphibians. For lizards, CTMax was positively influenced by the mean temperature of the wettest quarter. For anurans, the relationship is inverse; we recover a trend of decreasing CTMax when max temperature of warmest month and precipitation seasonality increase. There is an urgent need for studies to investigate the thermal tolerance of subsampled groups or even for which we do not have any information such as Gymnophiona, Serpentes, Amphisbaena, and Testudines. Broader phylogenetic coverage is mandatory for more accurate analyses of macroecological and evolutionary patterns for thermal tolerance indices as CTMax.

Metabolic rate increases with acclimation temperature and is associated with mitochondrial function in some tissues of threespine stickleback.

The metabolic rate (ṀO2) of eurythermal fishes changes in response to temperature, yet it is unclear how changes in mitochondrial function contribute to changes in ṀO2. We hypothesized that ṀO2would increase with acclimation temperature in the threespine stickleback (Gasterosteus aculeatus) in parallel with metabolic remodeling at the cellular level but that changes in metabolism in some tissues, such as liver, would contribute more to changes in ṀO2than others. Threespine stickleback were acclimated to 5, 12 and 20°C for 7 to 21 weeks. At each temperature, standard and maximum metabolic rate (SMR and MMR, respectively), and absolute aerobic scope (AAS) were quantified, along with mitochondrial respiration rates in liver, oxidative skeletal and cardiac muscles, and the maximal activity of citrate synthase (CS) and lactate dehydrogenase (LDH) in liver, and oxidative and glycolytic skeletal muscles. SMR, MMR and AAS increased with acclimation temperature, along with rates of mitochondrial phosphorylating respiration in all tissues. Low SMR and MMR at 5°C were associated with low or undetectable rates of mitochondrial complex II activity and a greater reliance on complex I activity in liver, oxidative skeletal muscle and heart. SMR was positively correlated with cytochrome c oxidase (CCO) activity in liver and oxidative muscle, but not mitochondrial proton leak, whereas MMR was positively correlated with CCO activity in liver. Overall, the results suggest that changes in ṀO2in response to temperature are driven by changes in some aspects of mitochondrial function in some, but not all, tissues of threespine stickleback.

Tissue-specific differences and temperature-dependent changes in Na,K-ATPase of the roach (Rutilus rutilus)

Na,K-ATPase activity is vital for virtually all cells of the animal body and the major consumer of cellular energy. However, Na,K-ATPase activity, the number of Na+ pump units, the catalytic rate of the pump, and their responses to thermal acclimation in different tissues of the same fish species have been seldom measured. Therefore, roach (Rutilus rutilus), eurythermal freshwater fish, was acclimated at 4 °C (cold-acclimated, CA) and 18 °C (warm-acclimated, WA), and the Na+ pump density and the temperature-dependence of Na,K-ATPase activity were determined in the heart, gills, kidney and brain. There were prominent tissues specific differences in Na,K-ATPase activity. The activity was highest in the brain (100%), whereas the activity of renal, branchial and cardiac enzymes was 55%, 9%, and 4% of the brain activity in the WA roach at 25 °C. The corresponding values for brain, kidney, gills and heart of the CA fish at 25 °C were 100%, 56%, 5% and 4%, respectively. The number of Na,K-ATPase α-subunits, determined by [3H]ouabain binding, strongly correlated with the Na,K-ATPase activity at R2 values of 0.99 and 0.85 for WA and CA fish, respectively. Acclimation to cold, increased the number of Na,K-ATPase α-subunits in the heart, kidney and brain (P < 0.05), but this did not appear as an increase in Na,K-ATPase activity. In the gills, Na,K-ATPase α-subunits did not change in cold-acclimation, but Na,K-ATPase activity was depressed. Although tissue-specific differences in Na,K-ATPase activity are largely determined by the density of α-subunits, differences in Na,K-ATPase activity within the same tissue due to temperature acclimation involve also other factors in addition to the number of Na+ pump units.

A warmer environment can reduce sociability in an ectotherm.

The costs and benefits of being social vary with environmental conditions, so individuals must weigh the balance between these trade-offs in response to changes in the environment. Temperature is a salient environmental factor that may play a key role in altering the costs and benefits of sociality through its effects on food availability, predator abundance, and other ecological parameters. In ectotherms, changes in temperature also have direct effects on physiological traits linked to social behaviour, such as metabolic rate and locomotor performance. In light of climate change, it is therefore important to understand the potential effects of temperature on sociality. Here, we took the advantage of a 'natural experiment' of threespine sticklebacks from contrasting thermal environments in Iceland: geothermally warmed water bodies (warm habitats) and adjacent ambient-temperature water bodies (cold habitats) that were either linked (sympatric) or physically distinct (allopatric). We first measured the sociability of wild-caught adult fish from warm and cold habitats after acclimation to a low and a high temperature. At both acclimation temperatures, fish from the allopatric warm habitat were less social than those from the allopatric cold habitat, whereas fish from sympatric warm and cold habitats showed no differences in sociability. To determine whether differences in sociability between thermal habitats in the allopatric population were heritable, we used a common garden breeding design where individuals from the warm and the cold habitat were reared at a low or high temperature for two generations. We found that sociability was indeed heritable but also influenced by rearing temperature, suggesting that thermal conditions during early life can play an important role in influencing social behaviour in adulthood. By providing the first evidence for a causal effect of rearing temperature on social behaviour, our study provides novel insights into how a warming world may influence sociality in animal populations.

Temperature determines the shift of thermal neutral zone and influences thermogenic capacity in striped hamsters.

The thermoneutral zone (TNZ) reflects the adaptation of mammals to their natural habitat. However, it remains unclear how TNZ shifts in response to variations in ambient temperature. To test the hypothesis that ambient temperature plays a key role in determining TNZ variations between seasons, we measured metabolic rate, body temperature, and cytochrome c oxidase (COX) activity of several visceral organs in striped hamsters (Cricetulus barabensis) either acclimated to semi-natural conditions over a year, or subjected to a gradual decrease in mean temperature from 30 ± 1°C to -15 ± 1°C. The TNZ range in striped hamsters differed seasonally, with a wider TNZ and a lower lower-critical temperature in winter compared to summer. The hamsters showed a considerable leftward shift of lower-critical temperature from 30°C to 20°C after the ambient temperature of acclimation from 30°C down to -15°C, whereas the upper-critical temperature of TNZ remained fixed at 32.5°C. The resting metabolic rate in thermoneutral zone (RMRt), nonshivering thermogenesis (NST), and COX activity of brown adipose tissue, liver, skeletal muscle, brain, and kidneys, increased significantly in hamsters acclimated at lower ambient temperatures. Following acute exposure to 5°C and -15°C, hamsters acclimated to 32.5°C had significantly lower maximal NST and lower serum thyroid tri-iodothyronine (T3 ) levels compared to those kept at 23°C. These findings suggest that acclimation to the upper-critical temperature of TNZ impairs the hamsters' thermogenic capacity to cope with extreme cold temperature. Reduced ambient temperature was mainly responsible for the leftward shift of TNZ in striped hamsters, which reflects the adaptation to cold environments.

Pseudouridylation of chloroplast ribosomal RNA contributes to low temperature acclimation in rice.

Ribosomal RNAs (rRNAs) undergo many modifications during transcription and maturation; homeostasis of rRNA modifications is essential for chloroplast biogenesis in plants. The chloroplast acts as a hub to sense environmental signals, such as cold temperature. However, how RNA modifications contribute to low temperature responses remains unknown. Here we reveal that pseudouridine (Ψ) modification of rice chloroplast rRNAs mediated by the pseudouridine synthase (OsPUS1) contributes to cold tolerance at seedling stage. Loss-function of OsPUS1 leads to abnormal chloroplast development and albino seedling phenotype at low temperature. We find that OsPUS1 is accumulated upon cold and binds to chloroplast precursor rRNAs (pre-rRNAs) to catalyse the pseudouridylation on rRNA. These modifications on chloroplast rRNAs could be required for their processing, as the reduction of mature chloroplast rRNAs and accumulation of pre-rRNAs are observed in ospus1-1 at low temperature. Therefore, the ribosome activity and translation in chloroplasts is disturbed in ospus1-1. Furthermore, transcriptome and translatome analysis reveals that OsPUS1 balances growth and stress-responsive state, preventing excess reactive oxygen species accumulation. Taken together, our findings unveil a crucial function of Ψ in chloroplast ribosome biogenesis and cold tolerance in rice, with potential applications in crop improvement.

PSVIII-B-6 Effect of Yeast on Rumen pH and Redox Potential in Ruminally-Cannulated Dairy Cows

Abstract Yeast products are used worldwide to stabilize the anaerobic rumen environment in dairy cattle. Multiparous lactating ruminally fistulated dairy cows (n = 4; ±150 DIM) were used in an 84-d 4×4 Latin square design to evaluate the effect of yeast on rumen pH and redox potential (eH). Periods were 21 d with 16 d used for treatment acclimation and HOBO pH and Temperature Data Loggers were placed in the rumen cranial sac on d 16 and removed on d 17 after a period of 24 hr for data collection. Cows were housed in a single pen and individually fed a basal dairy diet (CON) with no yeast culture or probiotics formulated for high milk yield targeting 5% feed refusals using a Calan Broadbent feeding system. Cows were randomly assigned to 1 of 4 treatments in period 1: CON, 14 g Diamond V XPC (XPC), 5 g Phileo-Lesaffre Actisaf HR+ (HR+), and HR+ 5 g Phileo-Lesaffre Safmannan (HR+Saf). Feed was delivered twice daily. Treatments were top-dressed at 0630 hr to ensure treatment consumption. Data were analyzed using GLIMMIX procedure of SAS 9.4. Significance was determined at P ≤ 0.05 and tendencies were considered at P ≤ 0.15. A treatment by time interaction occurred for rumen pH (P = 0.02). All yeast treatments were different than CON (P &amp;lt; 0.01), with no differences between yeast treatments (P &amp;gt; 0.52). A treatment by time interaction for eH (P = 0.04) occurred. Yeast eH was less than CON (P &amp;lt; 0.01). Redox potential decreased for HR+ compared to XPC (P = 0.04), while HR+Saf tended to decrease eH compared to XPC (P = 0.11). Over time, eH increased after feedings (P &amp;lt; 0.01). Data indicated that adding yeast to a dairy diet promoted an anaerobic environment, increasing rumen efficiency in lactating dairy cattle.

Global identification of quantitative trait loci and candidate genes for cold stress and chilling acclimation in rice through GWAS and RNA-seq

Associated analysis of GWAS with RNA-seq had detected candidate genes responsible for cold stress and chilling acclimation in rice. Haplotypes of two candidate genes and geographic distribution were analyzed. To explore new candidate genes and genetic resources for cold tolerance improvement in rice, genome-wide association study (GWAS) mapping experiments with 351 rice core germplasms was performed for three traits (survival rate, shoot length and chlorophyll content) under three temperature conditions (normal temperature, cold stress and chilling acclimation), yielding a total of 134 QTLs, of which 54, 59 and 21 QTLs were responsible for normal temperature, cold stress and chilling acclimation conditions, respectively. Integrated analysis of significant SNPs in 134 QTLs further identified 116 QTLs for three temperature treatments, 53, 43 and 18 QTLs responsible for normal temperature, cold stress and chilling acclimation, respectively, and 2 QTLs were responsible for both cold stress and chilling acclimation. Matching differentially expressed genes from RNA-seq to 43 and 18 QTLs for cold stress and chilling acclimation, we identified 69 and 44 trait-associated candidate genes, respectively, to be classified into six and five groups, particularly involved in metabolisms, reactive oxygen species scavenging and hormone signaling. Interestingly, two candidate genes LOC_Os01g04814, encoding a vacuolar protein sorting-associating protein 4B, and LOC_Os01g48440, encoding glycosyltransferase family 43 protein, showed the highest expression levels under chilling acclimation. Haplotype analysis revealed that both genes had a distinctive differentiation with subpopulation. Haplotypes of both genes with more japonica accessions have higher latitude distribution and higher chilling tolerance than the chilling sensitive indica accessions. These findings reveal the new insight into the molecular mechanism and candidate genes for cold stress and chilling acclimation in rice.

Meta-analysis reveals weak but pervasive plasticity in insect thermal limits

Extreme temperature events are increasing in frequency and intensity due to climate change. Such events threaten insects, including pollinators, pests and disease vectors. Insect critical thermal limits can be enhanced through acclimation, yet evidence that plasticity aids survival at extreme temperatures is limited. Here, using meta-analyses across 1374 effect sizes, 74 studies and 102 species, we show that thermal limit plasticity is pervasive but generally weak: per 1 °C rise in acclimation temperature, critical thermal maximum increases by 0.09 °C; and per 1 °C decline, critical thermal minimum decreases by 0.15 °C. Moreover, small but significant publication bias suggests that the magnitude of plasticity is marginally overestimated. We find juvenile insects are more plastic than adults, highlighting that physiological responses of insects vary through ontogeny. Overall, we show critical thermal limit plasticity is likely of limited benefit to insects during extreme climatic events, yet we need more studies in under-represented taxa and geographic regions.

Thermal biology of tambaqui (Colossoma macropomum): General insights for aquaculture in a changing world

AbstractIn this study, we review the state of the knowledge regarding the thermal biology of tambaqui (Colossoma macropomum) with emphasis on reproductive, zootechnical, metabolic, physiological and molecular aspects, which may direct paths for new research. We observed an optimal range for performance of the species, since it grows and reproduces well between 25 and 32°C, though does not tolerate temperatures below 23°C. Temperatures above 30°C cause disturbances in the processes of reproduction and development of embryos and larvae of tambaqui. Its metabolism is influenced by the size of the animal, with greater oxygen consumption in smaller animals and at higher temperatures. Haematology is one of the most often investigated fields and shows an elevation of the analysed blood parameters according to elevation in temperature, which, above 35°C, seems to be harmful to animals. However, studies are needed that examine the relationships between temperature and nutritional aspects (protein, lipid and carbohydrate metabolism), the cellular responses, the relationship with other environmental parameters (pH, oxygen, dissolved organic carbon), pollutants, ionic regulation and excretion, aerobic metabolism, growth and reproduction under warm conditions (&gt;32°C; +60 days). There is also the need to determine the thermal limits of the species as a function of different acclimation temperatures.

Critical thermal maximum and minimum of juvenile shortnose sturgeon ( Acipenser brevirostrum ) acclimated to 12 and 18°C

Thermal tolerance is crucial to understanding the biology of fishes and their responses to changes in temperatures, such as that produced by climate change. Shortnose sturgeon (Acipenser brevirostrum) is an endangered species (USA) and a species of special concern (Canada) that live on the eastern coast of North America. Although previous studies have focused on the acute critical thermal maximum (CTmax) of shortnose sturgeon, nothing is known with respect to their acute critical thermal minimum (CTmin) and the overall thermal tolerance of this species. This study examined the upper (CTmax) and lower (CTmin) thermal tolerance of shortnose sturgeon acclimated to 12 and 18°C. CTmax increased with increasing acclimation temperature; however, there was no significant relationship between acclimation temperature and CTmin. Taken together, the results of the present study show that shortnose sturgeon are well adapted to tolerate acute exposures to both cold and warm water environments.

Tolerance of an acute warming challenge declines with body mass in Nile tilapia: evidence of a link to capacity for oxygen uptake.

It has been proposed that larger individuals within fish species may be more sensitive to global warming, as a result of limitations in their capacity to provide oxygen for aerobic metabolic activities. This could affect size distributions of populations in a warmer world but evidence is lacking. In Nile tilapia Oreochromis niloticus (n=18, mass range 21-313 g), capacity to provide oxygen for aerobic activities (aerobic scope) was independent of mass at an acclimation temperature of 26°C. Tolerance of acute warming, however, declined significantly with mass when evaluated as the critical temperature for fatigue from aerobic swimming (CTSmax). The CTSmax protocol challenges a fish to meet the oxygen demands of constant aerobic exercise while their demands for basal metabolism are accelerated by incremental warming, culminating in fatigue. CTSmax elicited pronounced increases in oxygen uptake in the tilapia but the maximum rates achieved prior to fatigue declined very significantly with mass. Mass-related variation in CTSmax and maximum oxygen uptake rates were positively correlated, which may indicate a causal relationship. When fish populations are faced with acute thermal stress, larger individuals may become constrained in their ability to perform aerobic activities at lower temperatures than smaller conspecifics. This could affect survival and fitness of larger fish in a future world with more frequent and extreme heatwaves, with consequences for population productivity.

Metabolic scope, performance and tolerance of juvenile European sea bass Dicentrarchus labrax upon acclimation to high temperatures.

European sea bass is a species of great commercial value for fisheries and aquaculture. Rising temperatures may jeopardize the performance and survival of the species across its distribution and farming range, making the investigation of its thermal responses highly relevant. In this article, the metabolic scope, performance, and tolerance of juvenile E. sea bass reared under three high water temperatures (24, 28, 33°C), for a period of three months was evaluated via analysis of selected growth performance and physiological indicators. Effects on molecular, hormonal, and biochemical variables were analyzed along with effects of acclimation temperature on the metabolic rate and Critical Thermal maximum (CTmax). Despite signs of thermal stress at 28°C indicated by high plasma cortisol and lactate levels as well as the upregulation of genes coding for Heat Shock Proteins (HSP), E. sea bass can maintain high performance at that temperature which is encouraging for the species culture in the context of a warming ocean. Critical survivability thresholds appear sharply close to 33°C, where the aerobic capacity declines and the overall performance diminishes. European sea bass demonstrates appreciable capacity to cope with acute thermal stress exhibiting CTmax as high as 40°C for fish acclimated at high temperatures, which may indicate resilience to future heatwaves events.

Membrane lipid sensitivity to ocean warming and acidification poses a severe threat to Arctic pteropods

Ocean warming and acidification will be most pronounced in the Arctic. Both phenomena severely threaten thecosome pteropods (holoplanktonic marine gastropods) by reducing their survival (warming) and causing the dissolution of their aragonitic shell (acidification). Lipids, particularly phospholipids, play a major role in veligers and juveniles of the polar thecosome pteropodLimacina helicinacomprising more than two-thirds of their total lipids. Membrane lipids (phospholipids) are important for the temperature acclimation of ectotherms. Hence, we experimentally investigated ocean warming and acidification effects on total lipids, lipid classes, and fatty acids of Arctic early-stageL. helicina. The temperature and pCO2treatments chosen resembled Representative Concentration Pathway model scenarios for this century. We found a massive decrease in total lipids at elevated temperatures and at the highest CO2concentration (1,100μatm) of thein situtemperature. Clearly, temperature was the overriding factor. Total lipids were reduced by 47%–70%, mainly caused by a reduction of phospholipids by up to 60%. Further, based on pHTdevelopment in the incubation water of pteropods during the experiment, some evidence exists for metabolic downregulation in pteropods at high factor levels of temperature and pCO2. Consequently, the cell differentiation and energy balance of early-stage larvae were probably severely compromised. Comparison of our experimental with ‘wild’ organisms suggests phospholipid reduction to values clearly outside natural variability. Based on the well-known significance of phospholipids for membranogenesis, early development, and reproduction, negative warming effects on such a basal metabolic function may be a much more immediate threat for pteropods than so far anticipated shell dissolution effects due to acidification.

Head-tail-head neural wiring underlies gut fat storage in Caenorhabditis elegans temperature acclimation

Animals maintain the ability to survive and reproduce by acclimating to environmental temperatures. We showed here that Caenorhabditis elegans exhibited temperature acclimation plasticity, which was regulated by a head-tail-head neural circuitry coupled with gut fat storage. After experiencing cold, C. elegans individuals memorized the experience and were prepared against subsequent cold stimuli. The cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) regulated temperature acclimation in the ASJ thermosensory neurons and RMG head interneurons, where it modulated ASJ thermosensitivity in response to past cultivation temperature. The PVQ tail interneurons mediated the communication between ASJ and RMG via glutamatergic signaling. Temperature acclimation occurred via gut fat storage regulation by the triglyceride lipase ATGL-1, which was activated by a neuropeptide, FLP-7, downstream of CREB. Thus, a head-tail-head neural circuit coordinated with gut fat influenced experience-dependent temperature acclimation.

Temperature acclimation in hot-spring snakes and the convergence of cold response

Animals have evolved sophisticated temperature-sensing systems and mechanisms to detect and respond to ambient temperature changes. As a relict species endemic to the Qinghai-Tibet Plateau, hot-spring snake (Thermophis baileyi) survived the dramatic changes in climate that occurred during plateau uplift and ice ages, providing an excellent opportunity to explore the evolution of temperature sensation in ectotherms. Based on distributional information and behavioral experiments, we found that T. baileyi prefer hot-spring habitats and respond more quickly to warmth than other two snakes, suggesting that T. baileyi may evolve an efficient thermal-sensing system. Using high-quality chromosome-level assembly and comparative genomic analysis, we identified cold acclimation genes experiencing convergent acceleration in high-altitude lineages. We also discovered significant evolutionary changes in thermosensation- and thermoregulation-related genes, including the transient receptor potential (TRP) channels. Among these genes, TRPA1 exhibited three species-specific amino acid replacements, which differed from those found in infrared imaging snakes, implying different temperature-sensing molecular strategies. Based on laser-heating experiments, the T. baileyi-specific mutations in TRPA1 resulted in an increase in heat-induced opening probability and thermal sensitivity of the ion channels under the same degree of temperature stimulation, which may help the organism respond to temperature changes more quickly. These results provide insight into the genetic mechanisms underpinning the evolution of temperature-sensing strategies in ectotherms as well as genetic evidence of temperature acclimation in this group.

Thermal tolerance, safety margins and acclimation capacity assessments reveal the climate vulnerability of large yellow croaker aquaculture

With the ongoing climate change, marine aquaculture and other food production sectors will face new significant challenges in the next century. Despite the importance of these new challenges, understanding the dynamic thermal tolerance and thermal safety status of some major culture species remains scarce, including large yellow croaker (Larimichthys crocea), the most productive mariculture fish in China. Here, we conducted a relatively complete thermal biology assessment of cultured large yellow croaker using long-term acclimation experiments, critical thermal testing and the collected habitat sea surface temperature (SST) data. Changes in body size, oxidative stress and metabolic biomarkers during acclimation were also measured to evaluate the effects of prolonged thermal stress on performance. Results showed that the critical thermal limits of large yellow croaker acclimated at 11–30 °C ranged from 5.27 °C to 36.64 °C, and the total thermal tolerance zone was 444.74 °C2. Thermal limits increased as acclimation temperature rise, and the estimated acclimation response ratios ranged from 0.32 to 0.63, showing obvious thermal plasticity. The estimated post-acclimation thermal sensitivity values (0.80–1.28) for large yellow croaker acclimated at 11–30 °C were close to 1, and the heat- (5.78 °C) and cold-thermal safety margins (6.33 °C) were both high, showing sufficient thermal tolerance to cope with current observed highest SST and the predicted SST caused by climate change. However, performance results showed that long-term exposure to 30 °C would induce energy redistribution and tradeoffs between health/growth and heat tolerance, leading to significantly decreased body weight and increased superoxide dismutase activity in the gill. This result indicates a potential disadvantage of growing large yellow croaker in floating sea-cages, because the shallow culture depth, high density and limited moving spaces in this farming mode make the fish susceptible to fluctuations in SSTs, constrain their ability in behavioral thermoregulation, and increase the risks of hypoxia and disease infections. Thus, these tradeoffs may make the current floating sea-cage farming more vulnerable to elevated temperatures on production. Finally, since our recorded highest in situ SST and warming rate (in summer) have reached up to 30.1 °C and 1.2 °C/d, we propose that the large yellow croaker farms currently operating in the main producing area of China are already at the risk of summer heatwaves. In the future, more efforts should be made to the selection of heat-resilient strains or the exploration of alternative farming systems in large yellow croaker aquaculture industry to avoid or mitigate potential production decline.

Effects of temperature on parameters of calbasu Labeo calbasu fingerlings at laboratory condition

Temperature is an important environmental factor, plays significant role in the physiology of fish and aquatic ecosystem. In this study, we observed growth, hemato-biochemical parameters and water quality of calbasu, Labeo calbasu exposed to three different temperature regimes, such as 31, 34 and 37 °C respectively for 30 days. Two hundred and twenty fish were used, kept in 9 Aquarium, and were exposed to the different temperature. Highest body weight gain and lowest feed conversion ratio (FCR) was recorded at 31 °C. The highest specific growth rate was recorded at 31 °C followed by 34 °C and 37 °C. Survival at different acclimation temperatures was between 90.00±0.00, 90.0±0.00 and 88.00±0.00%, from lower to higher acclimation temperatures. Dissolved oxygen decreased and free CO2 increased significantly was found the study period. To determine the hemato-biochemical indices-hemoglobin (Hb) and blood glucose levels in the fish at each temperature. Hemoglobin (Hb) significantly decreased in response to temperature increases, while blood glucose levels displayed the opposite response. The present study revealed that high temperatures may be hazardous to Labeo calbasu.

Transcriptome analysis of the response to low temperature acclimation in Calliptamus italicus eggs

BackgroundCalliptamus italicus is a dominant species in the desert and semi-desert grassland. It is widely distributed throughout many regions such as Asia, Europe, North Africa and the Mediterranean, and has enormous destructive potential for agriculture and animal husbandry. The C. italicus overwintering as eggs in the soil through diapause, and the cold tolerance of locust eggs is the key to their ability to survive the winter smoothly to maintain the population.ResultsTranscriptome analysis of C. italicus eggs was carried out in this paper in constant low temperature acclimation, natural low temperature acclimation and room temperature. The differentially expressed genes related to cold tolerance were screened out, the differences in expression patterns under different low temperature acclimation were analyzed, and the genes in the significantly up-regulated pathways may play an important role in cold tolerance. The results show that different domestication modes can induce C. italicus eggs to express a large number of genes to alleviate low temperature damage, but C. italicus eggs are more sensitive to changes in temperature. Compared with the control, there are 8689 DEGs at constant low temperature and 14,994 DEGs at natural low temperature. KEGG analysis showed that DEGs were mainly enriched in pathways related to metabolism and biological systems under constant low temperature, and were mainly enriched in pathways related to biological systems and environmental information processing under natural low temperature. In addition, RNAi technology was used to further verify the regulation of genes in the significantly enriched up-regulated pathways on C. italicus eggs, and it was confirmed that the hatching rate of C. italicus eggs at low temperature was significantly reduced after interference.ConclusionsTranscriptome analysis of C. italicus eggs treated at different temperatures provided a theoretical basis for further understanding the adaptation mechanism of C. italicus eggs to low temperature. In addition, four potential RNAi target genes were verified in the eggs of C. italicus for the first time, providing new ideas for effective control of this species.