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371.
AbstractForced vital capacity (FVC) of children in the age group 10–12 years are reported as a function of quantum increase in PM2.5 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 PM2.5. The subjects are found to respond in a selective manner as plateau was observed for FVC values against some selected ranges of PM2.5 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. 相似文献
372.
Daizy R. Batish Harminder Pal Singh Mansimran Kaur Ravinder Kumar Kohli Surender Singh Yadav 《Acta Physiologiae Plantarum》2008,30(3):401-405
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. 相似文献
373.
We are pleased to announce a number of changes to the journal that will take effect from the start of 2003. 相似文献