Prevalence of adhesin and toxin genes among isolates of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> obtained from mastitic cattle

Staphylococcus aureus is recognized as a major etiological agent of the most important udder disease; mastitis. The virulence potential of S. aureus isolates is attributed to a combination of extracellular factors and invasive properties that are controlled at the genomic level. In this study molecular variations were studied among the 128 S. aureus isolates obtained from the mastitic crossbred cattle. The polymorphic patterns of protein A, coagulase, and IG genes were studied in the isolates using the PCR and PCR–RFLP methods. In addition, presence of other virulence genes responsible for the expression of adhesins and toxins was also screened. A considerable genetic variation was observed in amplified fragment of SPA, IG and CLF genes. The PCR–RFLP of COA gene yielded five different patterns. Occurrence of EBP, ENO and FNBA was found to be common in both high and low virulence isolates. However, the prevalence of FNBB and toxin genes was higher in clinical than subclinical isolates. The distribution proportions of adhesin genes EBP, FIB, FNBB, CNA, BBP, MAP CAP5, and CAP8 were 60.2, 59.4, 21.9, 6.3, 5.5, 80.5, 56.3, and 22.7%; for AGR I, II, III, and IV were 44.5, 32.8, 12.5, and 10.2%; and for toxins genes HLB, SEB, SEC, SED, SEE, SEG, and SEI were 82.0, 3.1, 5.5, 3.9, 0.8, 16.4, and 55.5%, respectively. The proportions of FNBB, EBP, FIB, HLB, BBP, SEG, and SEI genes were observed more in clinical cases. The significant genetic variations in SPA, COA, IG, and CLF genes were useful to differentiate the isolates that might be valuable for mastitis reduction programme.     

Apparent resistance to fall in forced vital capacity in children with increasing mass level of fine particulate: A physiological phenomenon

Abstract

Forced vital capacity (FVC) of children in the age group 10–12 years are reported as a function of quantum increase in PM_2.5 level in ambient air. The data are reported for the children in the categories based on their respective body mass index (BMI). FVC (% predicted) values decreased with increasing level of PM_2.5. The subjects are found to respond in a selective manner as plateau was observed for FVC values against some selected ranges of PM_2.5 concentration levels (74 µgm^?3 to >117 µgm^?3). To explain this unusual behavior, sac theory is proposed which explains the observations of FVC for subjects of all categories with different BMI values.     

Caffeine affects adventitious rooting and causes biochemical changes in the hypocotyl cuttings of mung bean (<Emphasis Type="Italic">Phaseolus aureus</Emphasis> Roxb.)

Caffeine (1,3,7-trimethylxanthine), a purine alkaloid found naturally in over 100 plant species, has recently been viewed as a safe chemical for management of pests including molluscs, slugs, snails, bacteria, and as a bird deterrent. It possesses phytotoxicity against plant species, yet the mechanism of action is lacking. A study was conducted to determine the effect of caffeine on the rooting of hypocotyl cuttings of mung bean (Phaseolus aureus) and the associated biochemical changes. At lower concentrations (<1,000 μM) of caffeine, though rooting potential was not affected, yet there was a significant decrease in the number of roots and root length. At 1,000 μM caffeine, there was a 68% decrease in the number of roots/primordia per cutting, whereas root length decreased by over 80%. However, no root formation occurred at 2,000 μM caffeine. Further investigations into the biochemical processes linked to root formation revealed that caffeine significantly affects protein content, activities of proteases, polyphenol oxidases (PPO) and total endogenous phenolic (EP) content, in the mung bean hypocotyls. A decrease in rooting potential was associated with a drastic reduction in protein content in the lower rooted portion, whereas the specific activity of proteases increased indicating that caffeine affects the protein metabolism. Activity of PPO decreased in response to caffeine, whereas EP content increased significantly indicating its non-utilization and thus less or no root formation. Respiratory ability of rooted tissue, as determined through TTC (2,3,5-triphenyl tetrazolium chloride) reduction, was impaired in response to caffeine indicating an adverse effect on the energy metabolism. The study concludes that caffeine interferes with the root development by impairing protein metabolism, affecting activity of PPO (and thus lignification), and EP content, which are the crucial steps for root formation.     

Announcement

We are pleased to announce a number of changes to the journal that will take effect from the start of 2003.