Effect of rearing temperature on growth and thermal tolerance of Schizothorax (Racoma) kozlovi larvae and juveniles

Effect of rearing temperature on growth and thermal tolerance of Schizothorax (Racoma) kozlovi Nikolsky larvae and juveniles was investigated. The fish (start at 12 d post hatch) were reared for nearly 6 months at five constant temperatures of 10, 14, 18, 22 and 26 °C. Then juvenile fish being acclimated at three temperatures of 14, 18 and 22 °C were chosen to determine their critical thermal maximum (CTMax) and lethal thermal maximum (LTMax) by using the dynamic method. Growth rate of S. kozlovi larvae and juveniles was significantly influenced by temperature and fish size, exhibiting an increase with increased rearing temperature, but a decline with increased fish size. A significant ontogenetic variation in the optimal temperatures for maximum growth were estimated to be 24.7 °C and 20.6 °C for larvae and juveniles of S. kozlovi, respectively. The results also demonstrated that acclimation temperature had marked effects on their CTMax and LTMax, which ranged from 32.86 °C to 34.54 °C and from 33.79 °C to 34.80 °C, respectively. It is suggested that rearing temperature must never rise above 32 °C for its successful aquaculture. Significant temperature effects on the growth rate and thermal tolerance both exhibit a plasticity pattern. Determination of critical heat tolerance and optima temperature for maximum growth of S. kozlovi is of ecological significance in the conservation and aquaculture of this species.     

Temperature-dependent physiological and biochemical responses of the marine medaka Oryzias melastigma with consideration of both low and high thermal extremes

This study aimed to investigate temperature effect on physiological and biochemical responses of the marine medaka Oryzias melastigma larvae. The fish were subjected to a stepwise temperature change at a rate of 1 °C/h increasing or decreasing from 25 °C (the control) to six target temperatures (12, 13, 15, 20, 28 and 32 °C) respectively, followed by a 7-day thermal acclimation at each target temperature. The fish were fed ad libitum during the experiment. The results showed that cumulative mortalities were significantly increased at low temperatures (12 and 13 °C) and at the highest temperature (32 °C). For the survivors, their growth profile closely followed the left-skewed ‘thermal performance curve’. Routine oxygen consumption rates of fish larvae were significantly elevated at 32 °C but suppressed at 13 and 15 °C (due to a high mortality, larvae from 12 °C were not examined). Levels of heat shock proteins and activities of malate dehydrogenase and lactate dehydrogenase were also measured in fish larvae exposed at 15, 25 and 32 °C. The activities of both enzymes were significantly increased at both 15 and 32 °C, where the fish larvae probably suffered from thermal discomfort and increased anaerobic components so as to compensate the mismatch of energy demand and supply at these thermal extremes. Coincidently, heat shock proteins were also up-regulated at both 15 and 32 °C, enabling cellular protection. Moreover, the critical thermal maxima and minima of fish larvae increased significantly with increasing acclimation temperature, implying that the fish could develop some degrees of thermal tolerance through temperature acclimation.     

Postprandial thermophily,transit rate,and digestive efficiency of juvenile cornsnakes,Pantherophis guttatus

We measured substrate temperature preference of juvenile cornsnakes in a linear thermal gradient during a fast and after feeding. After feeding the snakes selected temperatures approximately 6 °C warmer than those chosen by fasting snakes. We measured transit rates, the time from feeding to defecation, in snakes maintained at 22 or 32 °C or during ecdysis. Snakes at 32 °C had a significantly faster transit rate than those at 22 °C and during ecdysis snakes retained feces. The digestive efficiency ranged from 87% to 95% for individual snakes.     

Temperature modulates hepatic carbohydrate metabolic enzyme activity and gene expression in juvenile GIFT tilapia (Oreochromis niloticus) fed a carbohydrate-enriched diet

The effects of rearing temperature on hepatic glucokinase (GK), glucose-6-phosphatase (G6Pase) and Glucose-6-phosphate dehydrogenase (G6PD) activity and gene expression were studied in GIFT (genetically improved farmed tilapia) tilapia fed a high carbohydrate diet containing 28% crude protein, 5% crude lipid and 40% wheat starch. Triplicate groups of fish (11.28 g initial body weight) were fed the diet for 45 days at 22 °C, 28 °C or 34 °C. At the end of the trial, final body weight of juvenile at 28 °C (59.12 g) was higher than that of the fish reared at 22 °C (27.13 g) and 34 °C (43.17 g). Feed intake, feed efficiency and protein efficiency ratio were also better at 28 °C. Liver glycogen levels were higher at 28 °C, while plasma glucose levels were higher in the 22 °C group. Significant (P<0.05) effects of water temperature on enzymes activities and gene expression were observed. Hepatic GK activity and mRNA level were higher at 28 °C than at 34 °C. Higher G6Pase and G6PD activity and gene expression were observed at 22 °C. Overall, the data show that juveniles reared at 28 °C exhibited enhanced liver glycolytic capacity. In contrast, hepatic gluconeogenesis and lipogenesis were increased by low temperature (22 °C).     

The impact of temperature on the metabolome and endocrine metabolic signals in Atlantic salmon (Salmo salar)

The aim was to elucidate the effects of elevated temperature on growth performance, growth- and appetite-regulating hormones and metabolism in Atlantic salmon, Salmo salar. Post-smolts in seawater (average mass 175 g) that had been reared at 12 °C were kept at three temperatures (8, 12 and 18 °C) and sampled after one and three months. After three months, the fish kept in 18 °C had decreased growth rate and condition factor, and elevated plasma levels of growth hormone (GH) and leptin, compared with fish kept at the lower temperatures. Food conversion efficiency was also decreased at 18 °C, while at the same time protein uptake was improved and thus was not a limiting mechanism for growth. Redistribution of energy stores in fish at the highest temperature is evident as a preference of maintaining length growth during times of limited energy availability. NMR-based metabolomics analyses of plasma revealed that several metabolites involved in energy metabolism were negatively affected by temperature in the upper temperature range of Atlantic salmon. Specifically, the high temperature induced a decline of several amino acids (glutamine, tyrosine and phenylalanine) and a shift in lipid metabolism. It appears likely that the decreased food intake at the highest temperature is linked to an anorexigenic function of leptin, but also that the decreased food intake, feed conversion efficiency and condition factor can be linked to changes in GH endocrinology.     

A reduced core to skin temperature gradient,not a critical core temperature,affects aerobic capacity in the heat

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a “critical” core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h⁻¹ with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h⁻¹, grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m⁻² min⁻¹, respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.     

Cold storage of the egg parasitoids Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead (Hymenoptera: Scelionidae)

Adults of Trissolcus basalis and Telenomus podisi were stored either at 15 or 18 °C after their immature development had been completed at 18 or 25 °C. Longevity of the parasitoids in the storage temperatures was evaluated, as well as fecundity and longevity following their return to 25 °C after different periods in reproductive diapause. Temperature during immature development influenced female longevity and highest mean longevity was obtained for females that developed to the adult stage at 25 °C and then were stored at 15 °C (ca. 13 months for T. basalis and 10 months for Te. podisi). For adults of T. basalis that developed at 25 °C, storage periods of 120 or 180 days at 15 or 18 °C did not affect fecundity. The fecundity of T. basalis females that developed at 18 °C and were stored for 120 days at 15 or 18 °C was not affected; however, after remaining for 180 days, fecundity was reduced in ca. 30 and 50%, respectively. Storage of Te. podisi adults at 15 or 18 °C significantly reduced fecundity. It is concluded that adults of T. basalis can be stored in the adult stage at 15 or 18 °C between two soybean crop seasons for mass production purposes, aiming the biological control of stink bugs.     

Influence of temperature and exercise on growth performance,muscle, and adipose tissue in pacus (Piaractus mesopotamicus)

The aim of this study was to evaluate the effects of temperature and swimming exercise on fish growth in pacus (Piaractus mesopotamicus). Pacus weighing 0.9 – 1.9 g and 2.7 – 4.2 cm in standard length were cultivated at an initial density of 120 fish m⁻³ in 3 recirculation systems containing 6 water tanks at a volume of 0.5 m³ each at temperatures of 24, 28 and 32 °C. At each temperature, three tanks were modified to generate exercise activity in the specimens and force the fish to swim under a current speed of 27.5 cm s⁻¹. At the end of the experiment, the following metrics were evaluated: fish performance, morphometry (length, width, height and perimeter in different body positions), and the diameter and density of muscle and subcutaneous ventral adipose tissues. At 28 °C, pacus were both heavier and had greater weight gain after 240 days of cultivation. Additionally, exercise improved the feed conversion. An increase of 4 °C (30 °C) did not provide any improvement in the performance of the fish. However, swimming exercise improved the performance of pacus, providing increases of 38% and a 15% improvement in feed conversion. Both temperature and exercise influenced the body morphology (especially in the caudal region) and the cellularity of white and red muscle fibers and adipocytes.     

Effect of thermal stress on metabolic and oxidative stress biomarkers of Hoplosternum littorale (Teleostei,Callichthyidae)

The present study aimed to investigate in Hoplosternum littorale (Hancock, 1828) the effects of different water temperatures (10 °C, 25 °C-control group- and 33 °C) on physiologic and metabolic traits following acute (1 day) and chronic (21 days) exposures. We analyzed several biomarker responses in order to achieve a comprehensive survey of fish physiology and metabolism under the effect of this natural stressor. We measured morphological indices, biochemical and hematological parameters as well as oxidative stress markers. To evaluate energy consumption, muscle and hepatic total lipid, protein and glycogen concentrations were also quantified. Extreme temperatures exposures clearly resulted in metabolic adjustments, being liver energy reserves and plasma metabolites the most sensitive parameters detecting those changes. We observed reduced hepatosomatic index after acute and chronic exposure to 33 °C while glycogen levels decreased at both temperatures and time of exposure tested. Additionally, acute and chronic exposures to 10 °C increased liver lipid content and plasma triglycerides. Total protein concentration was higher in liver and lower in plasma after chronic exposures to 10 °C and 33 °C. Acute exposition at both temperatures caused significant changes in antioxidant enzymes tested in the different tissues without oxidative damage to lipids. Antioxidant defenses in fish failed to protect them when they were exposed for 21 days to 10 °C, promoting higher lipid peroxidation in liver, kidney and gills. According to multivariate analysis, oxidative stress and metabolic biomarkers clearly differentiated fish exposed chronically to 10 °C. Taken together, these results demonstrated that cold exposure was more stressful for H. littorale than heat stress. However, this species could cope with variations in temperature, allowing physiological processes and biochemical reactions to proceed efficiently at different temperatures and times of exposure. Our study showed the ability of H. littorale to resist a wide range of environmental temperatures and contributes for the understanding of how this species is adapted to environments with highly variable physicochemical conditions.     

Thermal tolerance and preferred temperature range of juvenile meagre acclimated to four temperatures

The present study reports the temperature tolerance, estimated using dynamic and static methodologies, and preferred temperature range, based on oxygen consumption rate (OCR), of juvenile meagre (Argyrosomus regius) (Asso, 1801) (3.4±0.9 g) after 30 days of acclimation at 18, 22, 26 and 30 °C. Meagre has dynamic and static thermal tolerance zones of 551 °C² and 460 °C², respectively and is a low resistance fish species, with a resistance zone area of 87 °C². The OCR of juvenile meagre at the above acclimation temperatures was 370, 410, 618 and 642 mg h⁻¹ kg⁻¹, respectively, and is significantly different (P<0.0001, n=20). The fact that OCR increases by rising temperatures and gradually decreases after 26 °C indicates that the preferred temperature range of juvenile meagre is between 26 and 30 °C. Our study suggests that meagre is unable to respond to low and high temperature variation in aquaculture facilities or its natural habitats.     

The effects of acute changes in temperature and oxygen availability on cardiac performance in winter flounder (Pseudopleuronectes americanus)

Studies on how flatfish cardiovascular function responds to environmental challenges are limited, and have largely relied upon indirect methodologies (i.e. Fick principle). Thus, we measured dorsal aortic blood pressure (P_DA) and cardiac function in 8 and 15 °C-acclimated flounder exposed to graded hypoxia, and in 8 °C-acclimated fish exposed to an acute temperature increase to their critical thermal maximum (CTM). The extent of bradycardia in 8 °C-acclimated fish (decrease in heart rate of 41%) was consistent with that observed for other teleosts, as was this species' CTM (25.8 ± 0.5 °C) and its cardiac response to increasing temperature. However, this study provides further examples of how cardiovascular function is controlled differently in the flounder as compared with other fishes. First, the onset of bradycardia in 8 °C-acclimated fish occurred earlier than expected for this inactive and hypoxia-tolerant species (60% water air saturation). Second, resting cardiac output was similar in flounder acclimated to 8 and 15 °C (～ 15 mL min^? 1 kg^? 1), and hypoxic bradycardia was surprisingly absent at 15 °C. Finally, systemic vascular resistance decreased when flounder were exposed to elevated temperature, and this resulted in a 26% fall in P_DA. These are novel findings, however, the extent to which the flounder's behaviour influenced some of the results is unclear.     

The effects of increased constant incubation temperature and cumulative acute heat shock exposures on morphology and survival of Lake Whitefish (Coregonus clupeaformis) embryos

Increasing incubation temperatures, caused by global climate change or thermal effluent from industrial processes, may influence embryonic development of fish. This study investigates the cumulative effects of increased incubation temperature and repeated heat shocks on developing Lake Whitefish (Coregonus clupeaformis) embryos. We studied the effects of three constant incubation temperatures (2 °C, 5 °C or 8 °C water) and weekly, 1-h heat shocks (+3 °C) on hatching time, survival and morphology of embryos, as these endpoints may be particularly susceptible to temperature changes. The constant temperatures represent the predicted magnitude of elevated water temperatures from climate change and industrial thermal plumes. Time to the pre-hatch stage decreased as constant incubation temperature increased (148 d at 2 °C, 92 d at 5 °C, 50 d at 8 °C), but weekly heat shocks did not affect time to hatch. Mean survival rates and embryo morphometrics were compared at specific developmental time-points (blastopore, eyed, fin flutter and pre-hatch) across all treatments. Constant incubation temperatures or +3 °C heat-shock exposures did not significantly alter cumulative survival percentage (~50% cumulative survival to pre-hatch stage). Constant warm incubation temperatures did result in differences in morphology in pre-hatch stage embryos. 8 °C and 5 °C embryos were significantly smaller and had larger yolks than 2 °C embryos, but heat-shocked embryos did not differ from their respective constant temperature treatment groups. Elevated incubation temperatures may adversely alter Lake Whitefish embryo size at hatch, but weekly 1-h heat shocks did not affect size or survival at hatch. These results suggest that intermittent bouts of warm water effluent (e.g., variable industrial emissions) are less likely to negatively affect Lake Whitefish embryonic development than warmer constant incubation temperatures that may occur due to climate change.     

Tetracycline-resistant bacteria as indicators of antimicrobial resistance in protected waters—The example of the Drwęca River Nature Reserve (Poland)

The objective of this study was to determine the suitability of Tet^R tetracycline-resistant bacteria as potential indicators of drug resistance, a parameter of the microbiological quality of river waters in natural reserves which are threatened by man-made pollution. The microbiological assays covered a 15-km long section of the upper reach of the Drw?ca River (Poland), a part of the European Ecological “Natura 2000” Network of nature protected areas. The quality of the investigated ecosystem was affected by surface runoffs from the river's agricultural catchment as well as outflows from three fish farms. The counts of Tet^R bacteria, incubated at 14 °C and 28 °C on TSA medium with sheep blood and tetracycline, were determined in river water samples. The highest counts of both bacterial groups were determined in samples collected from sites behind fish farms. A statistical analysis of the abundance of Tet^R14 °C and Tet^R28 °C bacteria revealed significant differences in the size of Tet^R28 °C populations at the studied sampling sites (p = 0.0011), which is why hemolytic bacteria of this group (HemTet^R28 °C) were selected for further investigations. The predominant strains in the group of 86 HemTet^R28 °C isolates obtained by 16S rRNA gene sequencing were Pseudomonas fluorescens (42 isolates) and Aeromonas hydrophila (28 isolates). Analyses of the identified HemTet^R28 °C strains demonstrated MIC ≥256 μg/ml in more than 50% isolates. The MAR index of HemTet^R28 °C was in the range of 0.67 at the control site to 1 at sites behind fish farms. The results suggest that tetracycline-resistant bacteria, in particular HemTet^R28 °C, are a reliable indicator of antimicrobial resistance and the microbial quality of surface waters polluted due to human activity. The above can be attributed to several factors: (I) the highest percentage share of HemTet^R28 °C among HPC28 °C was noted at sites behind fish farms, (II) tetracycline-resistant bacteria quickly respond to environmental changes, as demonstrated by the high level of resistance to tetracycline and a very high MAR index, and (III) genera/species that are easy to culture under laboratory conditions dominate in the qualitative and quantitative composition of the studied bacteria.     

Influence of water temperature and waterborne cadmium toxicity on growth performance and metallothionein–cadmium distribution in different organs of Nile tilapia,Oreochromis niloticus (L.)

Cadmium (Cd) is believed to be one of the most abundant and ubiquitously distributed toxins in the aquatic system. This metal is released to the aquatic environment from both anthropogenic sources, such as industrial, agricultural and urban effluents as well as natural sources, such as rocks and soils. Otherwise, the temperature increase of water bodies, which has been observed due to global climatic changes, has been shown to increase Cd toxicity for several aquatic animal species including fish. In the present study, Nile tilapia, Oreochromis niloticus (L.), (26.0±0.38 g) were reared at 20, 24, 28, or 32 °C and exposed to 0.0 or 0.5 mg Cd/L for 8 weeks to investigate effects of water temperature, Cd toxicity and their interaction on fish performance as well as metallothionein (MT) and Cd distribution in different fish organs. It was found that fish reared in Cd-free group at 28 °C showed the optimum growth and feed intake, while Cd-exposed fish showed low growth and feed intake irrespective to water temperature. A synergetic relationship between water temperature and Cd toxicity was observed where Cd toxicity increased as water temperature increased and the worse growth was obtained in Cd-exposed fish reared at 32 °C. Additionally, the highest Cd residues in different fish organs were detected in Cd-exposed fish reared at 32 °C. Similarly, MT concentrations in different fish organs increased as water temperature increased especially in Cd-exposed fish groups. A high positive correlation between MT and Cd concentrations in fish organs was detected. The distribution of MT and Cd levels was in the order of liver>kidney>gills>muscles. The present study revealed that the optimum water temperature suitable for Nile tilapia growth is 28 °C. Additionally, Cd exposure had a deteriorate effect on the growth and health of Nile tilapia. This hazardous effect increased as water temperature increased. Further, liver and kidney were the prime sites of Cd accumulation, while Cd load in the muscles was the lowest as compared to the other investigated organs.     

Thermal resistance time of estuarine fishes Etroplus suratensis and Therapon jarbua

The resistance time of Etroplus suratensis (Bloch) and Therapon jarbua (Forsskal) were determined for fish acclimated to a series of temperatures 20°C, 25°C, 28°C, 30°C, and 35°C. The results indicated that these two species of fishes showed increased thermal resistance when acclimation temperatures were increased or decreased, respectively. The biokinetic range of temperature for E. suratensis is from 12°C to 46°C and that for T. jarbua is from 8°C to 44°C.     

Metabolic and cellular stress responses of catfish,Horabagrus brachysoma (Günther) acclimated to increasing temperatures

We investigated the metabolic and cellular stress responses in an endemic catfish Horabagrus brachysoma acclimated to ambient (26 °C), 31, 33 and 36 °C for 30 days. After acclimation, fish were sampled to investigate changes in the levels of blood glucose, tissue glycogen and ascorbic acid, activities of enzymes involved in glycolysis (LDH), citric acid cycle (MDH), gluconeogenesis (FBPase and G6Pase), pentose phosphate pathway (G6PDH), protein metabolism (AST and ALT), phosphate metabolism (ACP and ALP) and energy metabolism (ATPase), and HSP70 levels in various tissues. Acclimation to higher temperatures (33 and 36 °C) significantly increased activities of LDH, MDH, ALP, ACP, AST, ALT and ATPase and blood glucose levels, whereas decreased the G6PDH enzyme activity and, tissue glycogen and ascorbic acid. Results indicated an overall increase in the carbohydrate, protein and lipid metabolism implying increased metabolic demands for maintaining homeostasis in fish acclimated to higher temperatures (33 and 36 °C). We observed tissue specific response of HSP70 in H. brachysoma, with significant increase in gill and liver at 33 and 36 °C, and in brain and muscle at 36 °C, enabling cellular protection at higher acclimation temperatures. In conclusion, H. brachysoma adjusted metabolic and cellular responses to withstand increased temperatures, however, these responses suggest that the fish was under stress at 33 °C or higher temperature.     

Thermal tolerance,growth and oxygen consumption of Labeo rohita fry (Hamilton, 1822) acclimated to four temperatures

A 30 day feeding trial was conducted using a freshwater fish, Labeo rohita (rohu), to determine their thermal tolerance, oxygen consumption and optimum temperature for growth. Four hundred and sixteen L. rohita fry (10 days old, 0.385±0.003 g) were equally distributed between four treatments (26, 31, 33 and 36 °C) each with four replicates for 30 days. Highest body weight gain and lowest feed conversion ratio (FCR) was recorded between 31 and 33 °C. The highest specific growth rate was recorded at 31 °C followed by 33 and 26 °C and the lowest was at 36 °C. Thermal tolerance and oxygen consumption studies were carried out after completion of growth study to determine tolerance level and metabolic activity at four different acclimation temperatures. Oxygen consumption rate increased significantly with increasing acclimation temperature. Preferred temperature decided from relationship between acclimation temperature and Q₁₀ values were between 33 and 36 °C, which gives a better understanding of optimum temperature for growth of L. rohita. Critical thermal maxima (CTMax) and critical thermal minima (CTMin) were 42.33±0.07, 44.81±0.07, 45.35±0.06, 45.60±0.03 and 12.00±0.08, 12.46±0.04, 13.80±0.10, 14.43±0.06, respectively, and increased significantly with increasing acclimation temperatures (26, 31, 33 and 36 °C). Survival (%) was similar in all groups indicating that temperature range of 26–36 °C is not fatal to L. rohita fry. The optimum temperature range for growth was 31–33 °C and for Q₁₀ values was 33–36 °C.     

Development response of Spodoptera exigua to eight constant temperatures: Linear and nonlinear modeling

Temperature-dependent development of Spodoptera exigua (Hübner) were evaluated at eight constant temperatures of 12, 15, 20, 25, 30, 33, 34 and 36 °C with a variation of 0.5 °C on sugar beet leaves. No development occurred at 12 °C and 36 °C. Total developmental time varied from 120.50 days at 15 °C to 14.50 days at 33 °C. As temperature increased from 15 °C to 33 °C, developmental rate (1/developmental time) of S. exigua increased but declined at 34 °C. The lower temperature threshold (T_min) was estimated to be 12.98 °C and 12.45 °C, and the thermal constant (K) was 294.99 DD and 311.76 DD, using the traditional and Ikemoto–Takai linear models, respectively. The slopes of the Ikemoto–Takai linear model for different immature stages were different, violating the assumption of rate isomorphy. Data were fitted to three nonlinear models to predict the developmental rate and estimate the critical temperatures. The T_min values estimated by Lactin-2 (12.90 °C) and SSI (13.35 °C) were higher than the value estimated by Briere-2 (8.67 °C). The estimated fastest development temperatures (T_fast) by the Briere-2, Lactin-2 and SSI models for overall immature stages development of S. exigua were 33.4 °C, 33.9 °C and 32.4 °C, respectively. The intrinsic optimum temperature (T_Φ) estimated from the SSI model was 28.5 °C, in which the probability of enzyme being in its native state is maximal. The upper temperature threshold (T_max) values estimated by these three nonlinear models varied from 34.00 °C to 34.69 °C. These findings on thermal requirements can be used to predict the occurrence, number of generations and population dynamics of S. exigua.     

Evaluation of structure and hydrolysis activity of Candida rugosa Lip7 in presence of sub-/super-critical CO2

This work aimed to assess the effect of sub-/super-critical CO₂ on the structure and activity of Candida rugosa Lip7 (CRL7) in its solution form. The structure was examined by SDS-PAGE gel electrophoresis, circular dichroism (CD) and fluorescence spectra photometry. Results revealed that the primary structure remained intact after sub-/super-critical CO₂ treatment, and the secondary structure altered at the pressure of 10 MPa and temperature 40 °C for 30 min incubation, but it was reflex to its native form with increasing incubation time up to 150 min under 10 MPa and 40 °C. Meanwhile, the tertiary structure via fluorescence spectra analysis showed that the intensity of the maximal emission wavelength at 338 nm decreased under the conditions of 10 MPa and 40 °C for 150 min. Furthermore, the residue hydrolysis activity and kinetics constants (V_max and K_m) of CRL7 treated with sub-/super-critical CO₂ were also investigated. In cases of 6 MPa and 35 °C, or 10 MPa and 40 °C for 30 min, activity variance of CRL7 was maybe caused by its secondary structure alteration. But in case of 10 MPa and 40 °C for 150 min, the tertiary structure change was perhaps responsibility for CRL7 activity enhancement.     

Individualising the exposure of −110 °C whole body cryotherapy: The effects of sex and body composition

The purpose of this study was to investigate the effects of whole body cryotherapy (WBC) on a range of thermoregulatory measures. We also sought to examine the influence of sex and body composition. A convenience sample of 18 healthy participants (10 males and 8 females) (27±6 yr) volunteered for this study. Temperature (core, tympanic, skin and mean body), heart rate, blood pressure, and thermal comfort and sensation were recorded pre- and post- (immediately and every 5 min until 35 min post) exposure to a single bout of WBC (30 s at −60 °C, 150 s at 110 °C). Anthropometric data (height, weight, body surface area, body mass index, fat mass and fat free mass) were also recorded. No significant differences in temperature (core, tympanic, skin and mean body), heart rate, blood pressure, or thermal comfort / sensation were observed between male and females at baseline. Immediately post WBC mean body (male:31.9±0.8 °C; female:31.0±0.9 °C; ∆ mean body temperature:0.9±0.1 °C; P≤0.05, d=0.64) and mean skin (male:22.1±2.2 °C; female:19.6±2.8 °C; ∆ mean skin temperature:−2.5±0.6 °C; d=0.99, P≤0.05) temperature was significantly different between sexes. Sex differences were also observed in regional skin temperature (male thigh, 20.8±1.1 °C; female thigh, 16.7±1.1 °C, ∆ mean thigh skin temperature:−4.1 °C; d=3.72; male calf, 20.5±1.1 °C; female calf, 18.2±1 °C, ∆ mean calf skin temperature:−2.3±0.1 °C; d=3.61; male arm, 21.7±1 °C; female arm, 19±0.4 °C, ∆ mean arm skin temperature: −2.7±0.3 °C; d=3.54; P≤0.05). Mean arterial pressure was significantly different over time (P≤0.001) and between sexes (male 0 mins:94±10 mmHg; female 0 mins:85±7 mmHg; male 35 mins:88±7 mmHg; female 35 mins:80±6 mmHg; P≤0.05). Combined data set indicated a strong negative relationship between skin temperature and body fat percentage 35 min’ post WBC (r=−0.749, P≤0.001) and for core temperature and body mass index in males only (r=0.726, P≤0.05) immediately after WBC. There were no significant differences between sexes in any other variables (heart rate, tympanic and perceptual variables). We observed sex differences in mean skin and mean body temperature following exposure to whole body cryotherapy. In an attempt to optimise treatment, these differences should be taken into account if whole body cryotherapy is prescribed.