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421.
A phospholipase A2 activity was characterized in adult rabbit lung. This activity was calcium- and deoxycholate-dependent and displayed an alkaline pH optimum. Km and Vmax were 0.176mM and 256.8 pmoles/min./mg protein respectively. The microsomal fraction displayed the highest enzymatic specific activity; the lowest activity was present in the cytosol. Yet this latter fraction accounted for the majority of the total activity. Although the specific activity was high within the lamellar body fraction this compartment contained only 2% of the total activity. Phospholipase A2 activity was inhibited by bromophenacyl bromide, chlorpromazine and mepacrine in decreasing order of effectiveness. Treatment of the microsomes with increasing concentrations of NaCl indicated that the lung phospholipase A2 activity was related loosely bound to the microsomal membranes and was maximally removed with salt at a concentration only slightly higher than physiological. Addition of calmodulin to the enzyme assay did not significantly alter hydrolysis of labelled phosphatidylcholine. 相似文献
422.
N J Temple P A Martin M J Connock 《Comparative biochemistry and physiology. B, Comparative biochemistry》1979,64(1):57-63
1. Rate sedimentation and isopycnic centrifugation were used to analyse the subcellular sites of enzymes in homogenates of goldfish intestinal mucosa. 2. The results allowed the following allocations to be made: carnitine acetyl transferase-mitochondrial and peroxisomal, xanthine dehydrogenase and NAD: alpha-glycerophosphate dehydrogenase soluble phase, NADP: isocitrate dehydrogenase soluble phase and mitochondrial, and 2-naphthyl laurate hydrolase microsomal and/or brush border. 3. Histochemistry confirmed the use of alkaline phosphatase and 1-naphthyl acetate esterase as brush border and microsome markers respectively. 4. Urate oxidase, allantoinase, allantoicase, xanthine oxidase and glycollate/lactate oxidase, activities were undetectable, and 1-naphthyl palmitate hydrolase was present only as a contaminant from pancreas. 相似文献
423.
Summary The earliest fossil stromatolites present evidence of a complex ecosystem of photosynthetic organisms. Because the origin of present life can be dated within a few hundred million years prior to these fossils, their complexity poses a problem. A heuristic model outlines the first radiation leading to the universal ancestor. 相似文献
424.
L J Temple 《BMJ (Clinical research ed.)》1981,282(6278):1782-1783
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426.
Stanley A. Temple 《Ostrich》2013,84(2-3):117-125
Temple, S. A. 1976. Observations of seabirds and shorebirds on Mauritius. Ostrich 47:117-125. During 1973 and 1974. 52 species of seabirds and shorebirds were found to occur on the island of Mauritius in the Indian Ocean. Ten species were breeding residents, 16 oceanic vagrants and 24 palaearctic migrants. Fifteen had not been previously reported from Mauritius. An annotated checklist of these species gives information on numbers, dates of occurrence. breeding biology, and behaviour. The impact of man's activities upon the seabird and shorebird populations on Mauritius is discussed with emphasis on persecution. habitat destruction, and chemical pollutants. 相似文献
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428.
The lichens Parmelia quercina, Parmelia sulcata, Evernia prunastri, Hypogymnia physodes, and Anaptychia ciliaris were exposed to ozone (O3) in controlled environment cuvettes designed to maintain the lichens at optimal physiological activity during exposure. Measurements of gas exchange, modulated chlorophyll (Chl) fluorescence, and pigment analysis were conducted before and after exposure to 300 mm3 (O3) m–3, 4 h per d for 14 d. No changes in the efficiency of photosystem 2 (PS2) photochemistry, the reduction state of QA, or the electron flow through PS2, measured by Chl fluorescence, were detected in any of the five lichen species studied. Additionally, neither photosynthetic CO2 assimilation nor xanthophyll cycle activity or photosynthetic pigment concentration were affected by high O3 concentrations. Thus the studied lichen species have significant capacities to withstand oxidative stresses induced by high concentration of O3. 相似文献