PubMed · 14522721
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Dale A Schoeller. 2003. But how much physical activity?. https://doi.org/10.1093/ajcn%2F78.4.669
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We present a comparative analysis of predicted highly expressed (PHX) genes in the low G+C Gram-positive genomes of Bacillus subtilis, Bacillus halodurans, Listeria monocytogenes, Listeria innocua, Lactococcus lactis, Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Clostridium acetobutylicum, and Clostridium perfringens. Most enzymes acting in glycolysis and fermentation pathways are PHX in these genomes, but not those involved in the TCA cycle and respiration, suggesting that these organisms have predominantly adapted to grow rapidly in an anaerobic environment. Only B. subtilis and B. halodurans have several TCA cycle PHX genes, whereas the TCA pathway is entirely missing from the metabolic repertoire of the two Streptococcus species and is incomplete in Listeria, Lactococcus, and Clostridium. Pyruvate-formate lyase, an enzyme critical in mixed acid fermentation, is among the highest PHX genes in all these genomes except for C. acetobutylicum (not PHX), and B. subtilis, and B. halodurans (missing). Pyruvate-formate lyase is also prominently PHX in enteric gamma-proteobacteria, but not in other prokaryotes. Phosphotransferase system genes are generally PHX with selection of different substrates in different genomes. The various substrate specificities among phosphotransferase systems in different genomes apparently reflect on differences in habitat, lifestyle, and nutrient sources.
During endurance exercise energy derives mainly from oxidation of carbohydrates and fat. Carbohydrates are stored in muscle and liver glycogen, fat is stored in adipose subcutaneous tissue and in intramuscular triglycerides. The intramuscular stores are the preliminary sources of fuel during muscular exercise. The principles of fatloading and carboloading are useful in increasing the intramuscular stores before exercise. The increased muscular reserves enable the athlete to maintain a higher intensity for longer time. During exercise depletion of glycogen may be delayed by ingestion of carbohydrates. Due to the limited resorption and oxidation of carbohydrates, efficacy of ingested carbohydrates is clearly limited. Due to the limitation in energy stores in the muscles and the limitation of energy ingestion during exercise, a considerable energy deficiency in long lasting events over days has to be considered.
Gene expression patterns in response to hydrostatic pressure were determined by whole genome microarray hybridization. Functional classification of the 274 genes affected by pressure treatment of 200 MPa for 30 min revealed a stress response expression profile. The majority of the >2-fold upregulated genes were involved in stress defense and carbohydrate metabolism while most of the repressed ones were in cell cycle progression and protein synthesis categories. Furthermore, uncharacterized genes were among the 10 highest expressed sequences and represented 45% of the total upregulated genes. The results of this study revealed a hydrostatic pressure-specific stress response pattern and suggested interesting information about the mechanisms involved in adaptation of cells to a high-pressure environment.