谈“十四五”生态保护与绿色发展的生态关系

 从“十四五”保护与发展的生态关系角度，探讨了生态保护与绿色发展的十大生态关系，阐述了生态保护和绿色发展中的一系列有关生态关系的生态智慧及生态技术，并对长江、黄河等流域的生态保护和修复提出了相关建议。     

The influence of chronic nicotine treatment on stress-induced gastric ulceration and emptying rate in rats.

Ten-day treatment with nicotine (5, 25 or 50 micrograms/ml drinking water) dose-dependently intensified gastric ulceration induced by cold-restraint, and emptying rate. Stomach contractions produced by graded doses of bethanechol i.v. were elevated further by nicotine treatment. It is suggested that chronic nicotine administration produces hypersensitivity of the gastric muscarinic receptors; stomach hypermotility contributes to the ulcer-worsening action of the alkaloid.     

《科学》杂志主编唐纳德·肯尼丹论述2001年度的重大科技进展

每一年 ,《Ｓｃｉｅｎｃｅ》杂志的编辑们都要聚在一起讨论该年度重大科技进展的提名问题。面对众多的新发现 ,往往是很具有挑战性的。今年我们遇到了一个尤为困难的任务 :找到一个能够和果蝇以及其他生命体的基因组测序相当的科技成就。果蝇以及其他生命体的基因组测序这项成果不仅仅席卷了去年的重大科技进展奖 ,而且它还导致了众多的后续项目 ,这决不亚于人类基因组草图的发表。这些后续的成功成了本年度科学中无人认领的珍宝中的一部分 ,而且就像去年一样完好的保存着。本年度重大科技进展的提名像去年的一样使人难忘 ,它涉及了从纳米技…     

Overcompensation and population cycles in an ungulate.

Although theoretical studies show that overcompensatory density-dependent mechanisms can potentially generate regular or chaotic fluctuations in animal numbers, the majority of realistic single-species models of invertebrate populations are not overcompensatory enough to cause sustained population cycles. The possibility that overcompensation may generate cycles or chaos in vertebrate populations has seldom been considered. Here we show that highly overcompensatng density-dependent mortality can generate recurrent population crashes consistent with those observed in a naturally limited population of Soay sheep. The observed interval of three or more years between crashes points to sharp 'focusing' of mortality over a narrow range of population density.     

Retrograde transport of endocytosed Shiga toxin to the endoplasmic reticulum.

Shiga toxin and some other protein toxins that act on targets in the cytosol have previously been shown to enter the trans-Golgi network. Transport by this route may be necessary for translocation of the toxin to the cytosol and for intoxication, but it is not known whether the enzymatically active part of the toxins actually enters the cytosol from the trans-Golgi network. It has been suggested that such toxins are transported in a retrograde manner to the endoplasmic reticulum and that translocation occurs in this organelle, but retrograde transport of endocytosed material beyond the trans-Golgi network has never been demonstrated. Here we show that in butyric acid-treated A431 cells endocytosed Shiga toxin is not only transported to the trans-Golgi network, but also to all Golgi stacks, to the endoplasmic reticulum and to the nuclear envelope. Furthermore, butyric acid sensitizes the cells to Shiga toxin, which is consistent with the possibility that retrograde transport is required for translocation of the toxin to the cytosol.