Molecular and physiological responses predict acclimation limits in juvenile brook trout (Salvelinus fontinalis)

ABSTRACT Understanding the resilience of ectotherms to high temperatures is essential because of the influence of climate change on aquatic ecosystems. The ability of species to acclimate to high temperatures may determine whether populations can persist in their native ranges. We examined physiological and molecular responses of juvenile brook trout (Salvelinus fontinalis) to six acclimation temperatures (5, 10, 15, 20, 23 and 25°C) that span the thermal distribution of the species to predict acclimation limits. Brook trout exhibited an upregulation of stress-related mRNA transcripts (heat shock protein 90-beta, heat shock cognate 71 kDa protein, glutathione peroxidase 1) and downregulation of transcription factors and osmoregulation-related transcripts (nuclear protein 1, Na+/K+/2Cl− co-transporter-1-a) at temperatures ≥20°C. We then examined the effects of acclimation temperature on metabolic rate (MR) and physiological parameters in fish exposed to an acute exhaustive exercise and air exposure stress. Fish acclimated to temperatures ≥20°C exhibited elevated plasma cortisol and glucose, and muscle lactate after exposure to the acute stress. Fish exhibited longer MR recovery times at 15 and 20°C compared with the 5 and 10°C groups; however, cortisol levels remained elevated at temperatures ≥20°C after 24 h. Oxygen consumption in fish acclimated to 23°C recovered quickest after exposure to acute stress. Standard MR was highest and factorial aerobic scope was lowest for fish held at temperatures ≥20°C. Our findings demonstrate how molecular and physiological responses predict acclimation limits in a freshwater fish as the brook trout in the present study had a limited ability to acclimate to temperatures beyond 20°C.

The effect of the drug “Bendamin” on the biochemical parameters of the blood of dogs in heart failure

Experimental studies obtained in recent years indicate the urgency of developing drugs of complex action to prevent the development of cardiovascular disease in dogs. This requires a much deeper study of the pathogenesis of heart failure, including cardiomyopathy. The aim of the study was to investigate the effect of the drug “Bendamin” on the biochemical parameters of the blood of dogs in heart failure. Two groups of dogs were formed for research: control (healthy) and experimental (sick). The 30-day experiment included 10 dogs of the control group and 10 dogs of the experimental (sick) breed of spaniel and dog 10–12 years of age. Treatment regimen for sick dogs: furosemide was administered orally on an empty stomach at 2 mg/kg every 12 hours; enalapril was administered orally at 0.5 mg/kg every 12 hours; bendamine was administered orally on an empty stomach at 20 mg/kg every 24 hours. It is recommended to divide the dose into two doses. An increase in the activity of aminotransferases (ALT by 59.2 %, AST – by 51.9 %) was found in the serum of dogs at heart failure. An increase in alkaline phosphatase activity was also found, which in the complex is an additional confirmation of changes in the heart muscle. Lactate dehydrogenase activity increased in the blood of sick dogs by 23.5 %. Minor changes in the content of total bilirubin and urea in the serum of sick dogs indicate the initial stage of liver pathology with impaired liver function due to congestion in the small circulation. This is also indicated by a decrease in the level of total protein in the blood of sick dogs, which was respectively 57.2 ± 3.57 g/l against the control group of 63.5 ± 4.15 g/l. On the basis of cardiac dysfunction and on the background of congestion, the function of not only the liver but also the kidneys is impaired (the so-called cardiorenal syndrome in heart failure). This is indicated by an increase in urea and creatinine by 38.5 and 36.9 %, respectively, compared with animals in the control group. The use of the drug “Bendamin” alleviated the manifestations of functional failure of the heart, liver and kidneys, as indicated by biochemical studies. Studies confirm the feasibility of using the drug “Bendamin” in dogs with the development of heart failure. The use of the drug “Bendamine” in patients with heart failure in dogs had a positive effect on the restoration of hematopoiesis and the normalization of biochemical parameters of the blood.

Molecular and physiological responses predict acclimation limits in juvenile brook trout (Salvelinus fontinalis)

Brook trout (Salvelinus fontinalis) populations are at risk of exposure to high water temperatures in the species’ native range in eastern North America. We quantified the physiological and molecular responses of juvenile brook trout to six acclimation temperatures that span the thermal distribution of the species (5, 10, 15, 20, 23, and 25°C). Using quantitative PCR (qPCR), we measured the mRNA transcript abundance of temperature-induced cellular stress genes to identify a potential sub-lethal temperature threshold for brook trout between 20–23°C. Brook trout exhibited an upregulation of stress-related genes (heat shock protein 90-beta; heat shock cognate 71 kDa protein; glutathione peroxidase 1) and a downregulation of transcription factors and osmoregulation-related genes (Na+/K+/2Cl− co-transporter-1-a; nuclear protein 1) at temperatures ≥20°C. We also used respirometry to assess the effects of the acclimation temperatures on oxygen consumption. Standard metabolic rate results indicated that energy expenditure was higher at temperatures ≥20°C. We then examined the effects of acclimation temperature on metabolic rate and blood plasma parameters in fish exposed to an acute exhaustive exercise and air exposure stress. Fish acclimated to temperatures ≥20°C exhibited elevated levels of plasma cortisol, muscle lactate, and plasma glucose after exposure to the acute stressors. After 24 h of recovery, fish showed longer metabolic recovery times at 15 and 20°C and cortisol levels remaining elevated at temperatures ≥20°C. Our findings suggest that brook trout may have a limited ability to acclimate to temperatures >20°C and increases in temperatures beyond 20°C may impact brook trout populations.

Serum and Muscle 1H NMR-Based Metabolomics Profiles Reveal Metabolic Changes Influenced by a Maternal Leucine-Rich Diet in Tumor-Bearing Adult Offspring Rats

A maternal leucine-rich diet showed a positive effect on the gastrocnemius muscle of adult tumor-bearing offspring. To improve the understanding of the metabolic alterations of cancer cachexia and correlate this to preventive treatment, we evaluated the 1H NMR metabolic profiles from serum and gastrocnemius muscle samples of adult Wistar rats. These profiles were initially analyzed, and chemometrics tools were applied to investigate the following groups: C, control group; W, tumor-bearing group; L, the group without tumors and with a maternal leucine-rich diet; WL, the tumor-bearing group with a maternal leucine-rich diet. Tumor growth that led to a high protein breakdown in the W group was correlated to serum metabolites such as tyrosine, phenylalanine, histidine, glutamine, and tryptophan amino acids and uracil. Also, decreased muscle lactate, inversely to serum content, was found in the W group. Conversely, in the WL group, increased lactate in muscle and serum profiles was found, which could be correlated to the maternal diet effect. The muscle lipidomics and NAD+, NADP+, lysine, 4-aminohippurate, and glutamine metabolites pointed to modified energy metabolism and lower muscle mass loss in the WL group. In conclusion, this exploratory metabolomics analyses provided novel insights related to the Walker-256 tumor-bearing offspring metabolism modified by a maternal leucine-rich diet and the next steps in its investigation.

Non-oxidative Energy Supply Correlates with Lactate Transport and Removal in Trained Rowers

This study aimed to test if the non-oxidative energy supply (estimated by the accumulated oxygen deficit) is associated with an index of muscle lactate accumulation during exercise, muscle monocarboxylate transporter content and the lactate removal ability during recovery in well-trained rowers. Seventeen rowers completed a 3-min all-out exercise on rowing ergometer to estimate the accumulated oxygen deficit. Blood lactate samples were collected during the subsequent passive recovery to assess individual blood lactate curves, which were fitted to the bi-exponential time function: La(t)= [La](0)+A1·(1–e–γ 1 t)+A2·(1–e–γ 2 t), where the velocity constants γ1 and γ2 (min–1) denote the lactate exchange and removal abilities during recovery, respectively. The accumulated oxygen deficit was correlated with the net amount of lactate released from the previously active muscles (r =0.58, P<0.05), the monocarboxylate transporters MCT1 and MCT4 (r=0.63, P<0.05) and γ2 (r=0.55, P<0.05). γ2 and the lactate release rate at exercise completion were negatively correlated with citrate synthase activity. These findings suggest that the capacity to supply non-oxidative energy during supramaximal rowing exercise is associated with muscle lactate accumulation and transport, as well as lactate removal ability.

NMR Metabolomic Analysis of Skeletal Muscle, Heart, and Liver of Hatchling Loggerhead Sea Turtles (Caretta caretta) Experimentally Exposed to Crude Oil and/or Corexit

We used nuclear magnetic spectroscopy (NMR) to evaluate the metabolic impacts of crude oil, Corexit 5900A, a dispersant, and a crude oil Corexit 5900A mixture exposure on skeletal muscle, heart, and liver physiology of hatchling loggerhead sea turtles (Caretta caretta). Tissue samples were obtained from 22 seven-day-old hatchlings after a four day cutaneous exposure to environmentally relevant concentrations of crude oil, Corexit 5900A, a combination of crude oil and Corexit 9500A, or a seawater control. We identified 38 metabolites in the aqueous extracts of the liver, and 30 metabolites in both the skeletal and heart muscle aqueous extracts, including organic acids/osmolytes, energy compounds, amino acids, ketone bodies, nucleosides, and nucleotides. Skeletal muscle lactate, creatines, and taurine concentrations were significantly lower in hatchlings exposed to crude oil than in control hatchlings. Lactate, taurine, and cholines appeared to be the basis of some variation in hatchling heart samples, and liver inosine, uracil, and uridine appeared to be influenced by Corexit and crude oil exposure. Observed decreases in concentrations of lactate and creatines may reflect energy depletion in skeletal muscle of oil-exposed animals, while decreased taurine concentrations in these animals may reflect higher oxidative stress.

Discrete physiological effects of beetroot juice and potassium nitrate supplementation following 4-wk sprint interval training

The physiological and exercise performance adaptations to sprint interval training (SIT) may be modified by dietary nitrate ([Formula: see text]) supplementation. However, it is possible that different types of [Formula: see text] supplementation evoke divergent physiological and performance adaptations to SIT. The purpose of this study was to compare the effects of 4-wk SIT with and without concurrent dietary [Formula: see text] supplementation administered as either [Formula: see text]-rich beetroot juice (BR) or potassium [Formula: see text] (KNO3). Thirty recreationally active subjects completed a battery of exercise tests before and after a 4-wk intervention in which they were allocated to one of three groups: 1) SIT undertaken without dietary [Formula: see text] supplementation (SIT); 2) SIT accompanied by concurrent BR supplementation (SIT + BR); or 3) SIT accompanied by concurrent KNO3 supplementation (SIT + KNO3). During severe-intensity exercise, V̇o2peak and time to task failure were improved to a greater extent with SIT + BR than SIT and SIT + KNO3 ( P < 0.05). There was also a greater reduction in the accumulation of muscle lactate at 3 min of severe-intensity exercise in SIT + BR compared with SIT + KNO3 ( P < 0.05). Plasma [Formula: see text] concentration fell to a greater extent during severe-intensity exercise in SIT + BR compared with SIT and SIT + KNO3 ( P < 0.05). There were no differences between groups in the reduction in the muscle phosphocreatine recovery time constant from pre- to postintervention ( P > 0.05). These findings indicate that 4-wk SIT with concurrent BR supplementation results in greater exercise capacity adaptations compared with SIT alone and SIT with concurrent KNO3 supplementation. This may be the result of greater NO-mediated signaling in SIT + BR compared with SIT + KNO3. NEW & NOTEWORTHY We compared the influence of different forms of dietary nitrate supplementation on the physiological and performance adaptations to sprint interval training (SIT). Compared with SIT alone, supplementation with nitrate-rich beetroot juice, but not potassium [Formula: see text], enhanced some physiological adaptations to training.