Heat and pH dependence of catalase. A comparative study

Effects of pH and heat were examined on the activity of enzyme catalase from human sources (normal and pathological sera, tissue homogenates, purified catalases). The pH optimum, temperature optimum and T50 values of purified catalases were lower than those of normal, or pathological sera and tissue homogenates. On contrast, the activation energy showed its highest value in purified catalase. These findings might be explained by the post-translational modification of enzyme catalase. The obtained results failed to enhance the diagnostic role of serum catalase determination, nevertheless, gave the optimal values of pH and temperature for catalase assay.     

Effect of long-term prostacyclin treatment on the gastric mucosa of rat

According to Bálint and Varró, oral administration of prostacyclin (PGI2) resulted in a significant increase of the DNA-content of the gastric mucosa within a short period of time. In the present study, there was no change in the protein content of the gastric mucosa after oral administration of 100 micrograms/kg/day of PGI2 for 80 days, while the DNA-content increased significantly. The RNA/DNA ratio decreased. Histologically a significant increase in the thickness of the gastric mucosa, as well as in the number of parietal and epithelial cells were found. The cell hyperplasia in the corpus mucosa was accompanied by a decreased number of G-cells of the antral mucosa. The increase of parietal cell number and the decrease of G-cell number after long term PGI2 administration might be explained by the divergent effect of treatment on the kinetics of the different cell types in the gastric mucosa.     

Isolating the influence of ontogeny helps predict island-wide variability in fish otolith chemistry

Reviews in Fish Biology and Fisheries - For marine fishes of commercial interest, defining how individuals vary in certain attributes, through ontogeny, and across space and time, can help expose...