Applying genomic approaches to delineate conservation strategies using the freshwater mussel Margaritifera margaritifera in the Iberian Peninsula as a model.

Effective conservation actions to counteract the current decline of populations and species require a deep knowledge on their genetic structure. We used Single Nucleotide Polymorphisms (SNPs) to infer the population structure of the highly threatened freshwater pearl mussel Margaritifera margaritifera in the Iberian Peninsula. A total of 130 individuals were collected from 26 locations belonging to 16 basins. We obtained 31,692 SNPs through Genotyping by Sequencing (GBS) and used this dataset to infer population structure. Genetic diversity given as observed heterozygosity was low. Pairwise FST comparisons revealed low levels of genetic differentiation among geographically close populations. Up to 3 major genetic lineages were determined: Atlantic, Cantabrian and Douro. This structure suggests a close co-evolutionary process with brown trout (Salmo trutta), the primordial fish host of this mussel in the studied area. Some sub-basins showed some genetic structuring, whereas in others no intrapopulation differentiation was found. Our results confirm that genetic conservation units do not match individual basins, and that knowledge about the genetic structure is necessary before planning recovery plans that may involve relocation or restocking. The same reasoning should be applied to strictly freshwater species that are sessile or have restricted dispersal abilities and are currently imperiled worldwide.

Mitochondrial dysfunction in non-alcoholic fatty liver disease and insulin resistance: cause or consequence?

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of the metabolic syndrome and refers to a spectrum of disorders ranging from steatosis to steatohepatitis, a disease stage characterized by inflammation, fibrosis, cell death and insulin resistance (IR). Due to its association with obesity and IR the impact of NAFLD is growing worldwide. Consistent with the role of mitochondria in fatty acid (FA) metabolism, impaired mitochondrial function is thought to contribute to NAFLD and IR. Indeed, mitochondrial dysfunction and impaired mitochondrial respiratory chain have been described in patients with non-alcoholic steatohepatitis and skeletal muscle of obese patients. However, recent data have provided evidence that pharmacological and genetic models of mitochondrial impairment with reduced electron transport stimulate insulin sensitivity and protect against diet-induced obesity, hepatosteatosis and IR. These beneficial metabolic effects of impaired mitochondrial oxidative phosphorylation may be related not only to the reduction of reactive oxygen species production that regulate insulin signaling but also to decreased mitochondrial FA overload that generate specific metabolites derived from incomplete FA oxidation (FAO) in the TCA cycle. In line with the Randle cycle, reduced mitochondrial FAO rates may alleviate the repression on glucose metabolism in obesity. In addition, the redox paradox in insulin signaling and the delicate mitochondrial antioxidant balance in steatohepatitis add another level of complexity to the role of mitochondria in NAFLD and IR. Thus, better understanding the role of mitochondria in FA metabolism and glucose homeostasis may provide novel strategies for the treatment of NAFLD and IR.

Adenosine A(3) receptors regulate heart rate, motor activity and body temperature.

AIM: To examine the phenotype of mice that lack the adenosine A(3) receptor (A(3)R). METHODS: We examined the heart rate, body temperature and locomotion continuously by telemetry over several days. In addition, the effect of the adenosine analogue R-N(6)-phenylisopropyl-adenosine (R-PIA) was examined. We also examined heat production and food intake. RESULTS: We found that the marked diurnal variation in activity, heart rate and body temperature, with markedly higher values at night than during day time, was reduced in the A(3)R knock-out mice. Surprisingly, the reduction in heart rate, activity and body temperature seen after injection of R-PIA in wild type mice was virtually eliminated in the A(3)R knock-out mice. The marked reduction in activity was associated with a decreased heat production, as expected. However, the A(3)R knock-out mice, surprisingly, had a higher food intake but no difference in body weight compared to wild type mice. CONCLUSIONS: The mice lacking adenosine A(3) receptors exhibit a surprisingly clear phenotype with changes in diurnal rhythm and temperature regulation. Whether these effects are due to a physiological role of A(3) receptors in these processes or whether they represent a role in development remains to be elucidated.

Effect of carbohydrate feeding during recovery from prolonged running on muscle glycogen metabolism during subsequent exercise.

This study examined the effect of carbohydrate (CHO) intake during a 4 h recovery from prolonged running on muscle glycogen metabolism during subsequent exercise. On 2 occasions, 7 male subjects ran for 90 min at 70 % maximum oxygen uptake VO(2 max) on a motorized treadmill (R1) followed by a 4 h rest period (REC) and a 15 min run (R2) consisting of 5 min at 60 % and 10 min at 70 % VO(2 max) During REC, each subject ingested a total of 2.7 l of an isotonic solution containing either 50 g of CHO (LOW) or 175 g of CHO (HIGH). Biopsy samples were obtained from the vastus lateralis immediately after R1, REC and R2. During REC, a higher muscle glycogen resynthesis was observed in HIGH when compared with LOW trial (75 +/- 20 vs. 31 +/- 11 mmol x kg dry matter (dm) -1, respectively; p < 0.01). Muscle glycogen utilization during R2 was similar between the HIGH and LOW trials (39 +/- 10 vs. 46 +/- 11 mmol x kg dm -1, respectively). These results suggest that ingestion of a large amount of CHO at frequent intervals during recovery from exercise does not affect the rate of muscle glycogen utilization during subsequent exercise.

Post-exercise vitamin C supplementation and recovery from demanding exercise.

The aim of this study was to investigate whether post-exercise vitamin C supplementation influences recovery from an unaccustomed bout of exercise. Sixteen male subjects were allocated to either a placebo (P; n=8) or vitamin C (VC) group ( n=8). Subjects performed a prolonged (90-min) intermittent shuttle-running test, and supplementation began after the cessation of exercise. Immediately after exercise the VC group consumed 200 mg of VC dissolved in a 500 ml drink, whereas the subjects in the P group consumed the drink alone. Later on the same day and then in the morning and evening of the following 2 days, subjects consumed additional identical drinks. Plasma VC concentrations in the VC group increased above those in the P group 1 h after exercise and remained above P values for the 3 days after exercise. Nevertheless, post-exercise VC supplementation was not associated with improved recovery. Post-exercise serum creatine kinase activities and myoglobin concentrations were unaffected by supplementation. Muscle soreness and the recovery of muscle function in the leg flexors and extensors were not different in VC and P groups. Furthermore, although plasma concentrations of interleukin-6 and malondialdehyde increased following exercise, there was no difference between VC and P groups. These results suggest that either free radicals are not involved in delaying the recovery process following a bout of unaccustomed exercise, or that the consumption of VC wholly after exercise is unable to deliver this antioxidant to the appropriate sites with sufficient expediency to improve recovery.

Comparison of dietary intake and eating behavior of professional road cyclists during training and competition.

The dietary intake and eating behavior of a group of professional elite road cyclists during high intensity training and competition was compared. Their eating pattern consisted of several snacks throughout the race or training, a meal eaten no later than 1 hr postexercise, supper, and breakfast. Protein intake showed a significant difference between evaluation times expressed in three ways: per total amount intake, by kg body weight, and percentage of energy supplied. Due to the high energy intake of these cyclists during training and competition (22.9 +/- 1.5, 22.4 +/- 1.7 MJ, respectively) they presented a high consumption of each macronutrient both in competition and in training. The eating behavior of these athletes was similar during breakfast (possibility to choose from among approximately 25 foods) and supper (set menu), with variation in the energy intake and a similar relative contribution of the different macronutrients. In general, it is possible to consider the professional road cyclists as a homogeneous group with a similar nutrition intake, eating habits, and nutritional needs throughout the more demanding periods of the season. Furthermore, differences found in protein intake between periods could not be explained by differences in the food available in competition and training periods.

Macronutrients intake of top level cyclists during continuous competition--change in the feeding pattern.

In order to quantify the nutritional status and the feeding pattern of professional cyclists during continuous competition, food intake was accurately measured and recorded using the weighed inventory of food (over three 24 h periods) during all meals in ten top professional cyclists during a real 3 weeks' competition. A 24 h period was defined as the time between the start of one stage and the next start. The 24 h period intake of energy, protein, fat, and carbohydrate was used to discover whether these intakes met requirements for endurance exercise. The average intake of energy and macronutrients was: energy = 23.5 +/- 1.8 MJ/24 h period, carbohydrate = 841.4 +/- 66.2 g/ 24h period; protein = 201.8 +/- 17.7g/24 h period; and fat = 158.6 +/- 16.3 g/24 h period. The carbohydrate, protein and fat contribution to energy was 60.0%, 14.5%, and 25.5% respectively. Fluid intake per 24h period was 3.29 +/- 0.94l (1.26 +/- 0.55 l during the race). Our study shows a similar energy intake in comparison with the only previous study in 1989 but there is a change in the feeding pattern of top level cyclists. A more important role is given to the intake of carbohydrate just after competitions together with an increase in protein intake. Both changes could have a positive effect on performance.