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61.
62.
Robert L. Ellison 《Hydrobiologia》1984,109(2):131-148
A rich and varied meiofauna inhabits a Cornish mudflat near the mouth of the Tamar River in southwestern England. Population densities range from 117 to 943 individuals · g–1 (wet) sediment (1.4–11.4 × 106 individuals · m–2), with foraminifera, harpacticoid copepods and nematodes appearing in nearly equal numbers and comprising most of the meiofauna. Seasonally, meiofaunal numbers rise and fall with solar radiation and vary inversely with river discharge. Two species, the atestate allogromiid A and the calcareous Haynesina germanica (Ehrenberg), far outnumber other foraminifera; their population densities and growth rates reach maxima in spring and summer.Monthly rates of sediment respiration are locally variable, but clearly increase from winter (4.13 ml O2 · m–2 · h–1 in December) to spring (38.87 ml O2 · m–2 · h–1 in April). Experiments and calculations ascribe approximately 30% of this total to the meiofauna (including microfauna and microflora), 50% to bacteria and less than 20% to chemical oxidation. A tentative energy budget for the mudflat suggests that secondary production by meiofauna is small as compared with coastal environments elsewhere, and that meiofaunal production (426 Kcal · m–2 · y–1) is nearly twice meiofaunal respiration (252 Kcal · m–2 · yr–1). 相似文献
63.
OXYGEN DIFFUSION IN PEA 总被引:4,自引:2,他引:2
64.
Bernhard Kadenbach 《Journal of bioenergetics and biomembranes》1986,18(1):39-54
The present view on the regulation of respiration and ATP synthesis in higher organisms implies only Michaelis-Menten type kinetics and respiratory control as regulatory principles. Recent experimental observations, suggesting further regulatory mechanisms at respiratory chain complexes, are reviewed. A new hypothesis is presented implying regulation of respiration and ATP synthesis in higher organisms mainly via allosteric modification of respiratory chain complexes, in particular of cytochromec oxidase. The allosteric effectors, e.g., metabolites, cofactors, ions, hormones, and the membrane potential are suggested to change the activity and the coupling degree of cytochromec oxidase by binding to specific sites at nuclear coded subunits. Recent results on the structure and activity of cytochromec oxidase, supporting the hypothesis, are reviewed.Dedicated to Professor Dr. Carl Martius on the occasion of his 80th birthday. 相似文献
65.
66.
家兔脑桥臂旁内侧核区微量注射吗啡对中缝大核区单位放电的影响 总被引:1,自引:1,他引:0
实验在62只家兔上进行。结果观察到,中缝大核(NRM)区562个单位中,有118个单位的自发放电频率低,放电比较规则,动作电位时程长,易被微电泳5-羟色胺所阻遏,称为A 组单位。其余444个单位的自发放电频率高,动作电位时程短,称为B 组单位。大多数 B组单位对微电泳5-羟色胺不起反应。脑桥臂旁内侧核(NPBM)区微量注射吗啡(200μg/2μl)或静脉注射吗啡(3mg/kg)后,20个A 组单位中有19个发生兴奋效应,而49个B 组单位中仅有29个发生兴奋效应,而且A组单位发生兴奋的程度也比B组单位的高。这些结果提示,NRM区的A 组单位可能是5-羟色胺神经元,吗啡对这些神经元有相对选择性的兴奋作用。 在另外11只家兔上,应用辣根过氧化物酶(HRP)逆行追踪技术观察到,NPBM 区与NRM 区有纤维联系。 本实验结果提示,静脉注射吗啡所致的呼吸抑制,可能与吗啡作用于 NPBM,通过纤维联系,引起NRM 5-羟色胺神经元兴奋有关。 相似文献
67.
Cycling of soil carbon in the first year after a clear-felling was compared with that before the felling in a Japanese red
pine forest in Hiroshima Prefecture, west Japan. The daily mean temperature at the soil surface in summer was increased after
the felling in comparison to that before felling, and the water content of both the A0 layer and the surface mineral soil was decreased due to the loss of the forest canopy. The rate of weight loss of the A0 layer was reduced after felling. However, accumulation of the A0 layer rapidly decreased because of the lack of litter supply to the forest floor. Low soil respiration after felling was
mainly caused by the cessation of root respiration. Analysis of annual soil carbon cycling was then conducted using a compartment
model. The relative decomposition rate of the A0 layer decreased whereas that of humus and dead roots in mineral soil increased to some extent after felling. The accumulation
of carbon in mineral soil, however, increased slightly due to the supply of humus from roots killed by the felling. 相似文献
68.
69.
In the cucumber ( Cucumis sativus L. cv. Straight Eight) cotyledon expansion assay, cytokinin-stimulated ethylene production was separated from cytokinin-stimulated growth through the use of potassium and calcium salts. Low concentrations of KC1, which dramatically promoted growth induced by cytokinin, inhibited ethylene evolution, while CaCl2 at a concentration that had no effect on growth, strongly promoted the cytokinin-induced ethylene evolution. In contrast to the growth response, stimulation of ethylene production was not directly related to the presence of potassium or calcium but to their relative concentrations. Concentrations of KCl and CaCl2 which promoted ethylene evolution singly, strongly inhibited it when mixed together. Low rates of exogenous ethylene had no effect on the growth response. Both the growth and ethylene responses were found to be general cytokinin phenomena. Cotyledon respiration was promoted by KC1, CaCl2 and cytokinin, but its stimulation was not correlated with either growth or ethylene production. In the presence of KClm cytokinin-induced respiration sharply lowered the content of certain sugars during the large growth response and followed KCl uptake. Analysis of KCl uptake showed that its growth promoting synergism with cytokinin was not due to osmotic effects. 相似文献
70.
Alkylsulfonic acids and some S-containing detergents as sulfur sources for growth of Chlorella fusca
Chlorella fusca can utilize the following substances as sole sulfur sources for growth: C1 to C8 n-alkane-1-sulfonates, linear alkylbenzenes sulfonates (LAS), -sulfonated fatty acid esters, polyethylene glycol sulfate and alkylsulfates. Good sulfur sources are alkylsulfonic acids, which are comparable to sulfate. Ethanesulfonic acid was used for comparison of the growth on sulfate and on a sulfonic acid, because best growth was achieved on this C2-sulfonic acid.Growth data of Chlorella on the enviromental important detergents linear alkylbenzene sulfonic acids, -sulfonated fatty acid methylester, Texapon and Sulfopon are presented. So far only microorganisms have been discussed as a source for degradation of sulfonic acids and detergents. It is suggested that green algae could be of similar importance for the biodegradation of these compounds.Abbreviations LAS
Linear alkylbenzene sulfonate
- ES
-sulfonated fatty acid methylester
- DTE
dithiocrythritol 相似文献