Relationships between Larval and Juvenile Abundance of Winter-Spawned Fishes in North Carolina, USA

We analyzed the relationships between the larval and juvenile abundances of selected estuarine-dependent fishes that spawn during the winter in continental shelf waters of the U.S. Atlantic coast. Six species were included in the analysis based on their ecological and economic importance and relative abundance in available surveys: spot Leiostomus xanthurus, pinfish Lagodon rhomboides, southern flounder Paralichthys lethostigma, summer flounder Paralichthys dentatus, Atlantic croaker Micropogonias undulatus, and Atlantic menhaden Brevoortia tyrannus. Cross-correlation analysis was used to examine the relationships between the larval and juvenile abundances within species. Tests of synchrony across species were used to find similarities in recruitment dynamics for species with similar winter shelf-spawning life-history strategies. Positive correlations were found between the larval and juvenile abundances for three of the six selected species (spot, pinfish, and southern flounder). These three species have similar geographic ranges that primarily lie south of Cape Hatteras. There were no significant correlations between the larval and juvenile abundances for the other three species (summer flounder, Atlantic croaker, and Atlantic menhaden); we suggest several factors that could account for the lack of a relationship. Synchrony was found among the three southern species within both the larval and juvenile abundance time series. These results provide support for using larval ingress measures as indices of abundance for these and other species with similar geographic ranges and winter shelf-spawning life-history strategies

Aerobic training attenuates nicotinic acetylcholine receptor changes in the diaphragm muscle during heart failure

Introduction: Heart failure (HF) is a progressive myopathy, with clinical signs of fatigue and limb weakness that can damage the nerve-muscle interaction, altering synaptic transmission and nicotinic acetylcholine receptors (nAChR) in neuromuscular junctions (NMJs). The diaphragm is composed of a mixed proportion of muscle fibres, and during HF, this muscle becomes slower and can alter its function. As exercise training is an accepted practice to minimise abnormalities of skeletal muscle during HF, in this study, we evaluated the hypothesis that aerobic training attenuates alterations in the expression of nAChR subunits in NMJs diaphragm during heart failure. Objective: The aim of this study was to evaluate the distribution and expression of nAChR subunits in the diaphragm muscle fibres of rats subjected to an aerobic training programme during HF. Methods: Control (Sham), control training (ShamTR), aortic stenosis (AS) and aortic stenosis training (ASTR) groups were evaluated. The expression of nAChR subunits (γ, α1, ε, β1 and δ) was determined by qRT-PCR, and NMJs were analysed using confocal microscopy. Results: We observed increased expression of the γ, α1 and β1 subunits in the AS group compared with the ASTR group. The distribution of NMJs was modulated in these groups. Discussion: HF alters the mRNA expression of nAChR subunits and the structural characteristics of diaphragm NMJs. In addition, aerobic training did notalter NMJs morphology but attenuated the alterations in heart structure and function and in nAChR subunit mRNA expression. Our findings demonstrate the beneficial effects of aerobic exercise training in maintaining the integrity of the neuromuscular system in the diaphragm muscle during HF and may be critical for non-pharmacological therapy to improve the quality of life for patients with this syndrome

Aerobic Exercise Training Prevents Heart Failure-Induced Skeletal Muscle Atrophy by Anti-Catabolic, but Not Anabolic Actions

Background: Heart failure (HF) is associated with cachexia and consequent exercise intolerance. Given the beneficial effects of aerobic exercise training (ET) in HF, the aim of this study was to determine if the ET performed during the transition from cardiac dysfunction to HF would alter the expression of anabolic and catabolic factors, thus preventing skeletal muscle wasting.Methods and Results: We employed ascending aortic stenosis (AS) inducing HF in Wistar male rats. Controls were sham-operated animals. At 18 weeks after surgery, rats with cardiac dysfunction were randomized to 10 weeks of aerobic ET (ASET) or to an untrained group (AS-UN). At 28 weeks, the AS-UN group presented HF signs in conjunction with high TNF-alpha serum levels; soleus and plantaris muscle atrophy; and an increase in the expression of TNF-alpha, NF kappa B (p65), MAFbx, MuRF1, FoxO1, and myostatin catabolic factors. However, in the AS-ET group, the deterioration of cardiac function was prevented, as well as muscle wasting, and the atrophy promoters were decreased. Interestingly, changes in anabolic factor expression (IGF-I, AKT, and mTOR) were not observed. Nevertheless, in the plantaris muscle, ET maintained high PGC1 alpha levels.Conclusions: Thus, the ET capability to attenuate cardiac function during the transition from cardiac dysfunction to HF was accompanied by a prevention of skeletal muscle atrophy that did not occur via an increase in anabolic factors, but through anti-catabolic activity, presumably caused by PGC1a action. These findings indicate the therapeutic potential of aerobic ET to block HF-induced muscle atrophy by counteracting the increased catabolic state.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP