荒漠灌丛土壤动物分布及其生态功能

在干旱、半干旱荒漠生态系统中,灌丛作为一种重要的植被类型,其独特的形态和生理适应特性能够有效促进退化生态系统结构与功能的恢复。土壤动物是荒漠生态系统中不可或缺的重要组成部分,对促进灌丛"肥岛"演变具有重要的生态作用,有利于灌丛生态功能的发挥及退化生态系统的恢复。近年来,国内外学者对荒漠灌丛微生境土壤动物的研究逐步深入,取得大量的研究成果。在此基础上,首先综述荒漠灌丛微生境土壤动物群落分布和生态功能,总结灌丛与土壤动物分布间作用关系的数学模型,针对荒漠灌丛土壤动物研究中存在的问题提出了未来可能的研究方向和建议。     

Changes in the content and structure of the coenzyme A moiety in the liver of diabetic mice (db/db) administered a regimen of nicotinamide

Alterations in the content and structure of CoA moiety typical of hyperlipogenesis (a rise in total and free CoA levels, a drop in short-chained fatty acyl-CoA/CoA and long-chained fatty acyl-CoA/CoA ratios) were found in the liver of obese mice with non-insulin-dependent diabetes (db/db). The treatment of diabetic mice with nicotinamide, an antilipemic drug, was accompanied by a decrease in total and free CoA levels and a rise in short-chained fatty acyl-CoA content and short-chained fatty acyl-CoA/CoA and long-chained fatty acyl-CoA/CoA ratios, probably leading to the inhibition of the enzymes of primary lipogenesis steps. It is suggested that CoA moiety structure is essential as an integral index regulating the rate of fatty acid biosynthesis in diabetes mellitus.     

Sensitive control of heart rate in monkeys using burst stimulation of the vagus nerve

Burst vagus stimulation led to synchronization of the cardiac and vagal rhythms at certain frequency ranges. The increase of the number of impulses in a burst from 1 to 16 extended the range of synchronization and shifted it towards lower frequencies forming a total range of exact regulation of the heart rate within 85--40% of the initial rate. It was suggested that vagal effect consists of tonic and synchronizing components.