[Show abstract][Hide abstract] ABSTRACT: The number of oocytes recovered from Bos taurus indicus females subjected to ovum pick-up averaged two to four times greater compared to Bos taurus taurus females. The objective of the present study was to test the hypothesis that this difference in oocyte yield was due to more preantral follicles in the ovaries of Bos indicus females. Ovaries (n = 64) from Nelore (Bos indicus) fetuses (n = 10), heifers (n = 12), and cows (n = 10), and Aberdeen Angus (Bos taurus) fetuses (n = 10), heifers (n = 12), and cows (n = 10) were cut longitudinally into halves, fixed, and processed for histological evaluation. The number of preantral follicles was estimated by counting them in each histological section, using the oocyte nucleus as a marker and employing a correction factor. The average number of preantral follicles in the ovaries of Bos indicus vs Bos taurus was (mean ± SD) 143,929 ± 64,028 vs 285,155 ± 325,195 for fetuses, 76,851 ± 78,605 vs 109,673 ± 86,078 for heifers, and 39,438 ± 31,017 vs 89,577 ± 86,315 for cows (P > 0.05). The number of preantral follicles varied greatly among individual animals within the same category, as well as between breeds. In conclusion, we inferred that the higher oocyte yield from Bos indicus females was not due to a greater ovarian reserve of preantral follicles. Therefore, mechanisms controlling follicle development after the preantral stage likely accounted for differences between Bos indicus and Bos taurus females in number of oocytes retrieved at ovum pick-up.
[Show abstract][Hide abstract] ABSTRACT: Gelatinase is a potential virulence factor in Enterococci which are opportunistic pathogens that cause various types of infections in humans. The production of gelatinase was studied in 95 Enterococcus faecalis strains isolated from different types of clinical sources. Various environmental parameters including culture medium, temperature, pH, divalent cations and carbon sources were examined for their effect on production of gelatinase. Enzyme activity was determined based on gelatin degradation in agar plates by filter-paper disks impregnated with bacterial cells, as evidenced by the formation of an opaque halo. Gelatinase production was sensitive to heat at a temperature greater than 50°C, showing to be associated with time of heat treatment. A greater number of enterococcal strains produced gelatinase when grown in medium containing beef extract and peptone as nutrient agar. Gelatinase activity was detected over wide pH range with an optimum at pH 8. Ca 2+ and Zn 2+ caused a reduction in gelatinase production, while other common divalent cations (Fe 2+ and Cu 2+) inhibited it or had no effect (Mg 2+). Gelatinolytic activity varied greatly when bacterial cells were supplemented with different carbohydrates as the carbon source and increased with arabinose, xylose, glucose, maltose and mannose, while unchanged or decreased with other various sugars. The results show that gelatinase production is strongly influenced by different environmental factors. Further studies are warranted to determine the mechanisms controlling the production of this potential virulence factor in Enterococci.
Preview · Article · Apr 2010 · African journal of microbiology research