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241.
Summary The terpenoid aldehydes, desoxyhemigossypol, desoxy-6-methoxyhemigossypol, hemigossypol, 6-methoxyhemigossypol, gossypol, 6-methoxygossypol, and 6,6′-dimethoxygossypol, previously reported to be present in cotton roots (Gossypium hivsutum L.) were found on absorbing surfaces adjacent to roots. Infection of hypocotyls byRhizoctonia solani increased the quantity of terpenoids exuded by roots. Because these compounds are antimicrobial, their presence in the rhizosphere should be considered in studies of the microflora of cotton roots.  相似文献   
242.
A sensitive and specific radioimmunoassay for glycine and taurine conjugates of lithocholic acid (CLCA) has been developed. 3H-glycolithocholic acid (S.A. = 17Ci/mmol) was used as tracer. Separation of free from antibody-bound bile acid was carried out using ammonium sulphate (saturated solution). The antiserum showed high specificity for both glyco and tauro conjugated lithocholate (100% cross reaction) and lithocholic acid (25% cross reaction). The sensitivity of the assay (1 pmole/tube), was adequate for measuring CLCA in peripheral blood and hepatic tissue in man.  相似文献   
243.
The pancreatic epithelium of intact frog has been studied using morphometry, cytochemistry and electron microscopy. A low level of DNA synthesis was shown to be characteristic of pancreatic epithelium of frogs caught in winter. The B/A cell volume ratio is 3.68 +/- 0.16 and 2.55 +/- 0.36 in small and median pancreatic islets, resp. A-, B-, D-cells are found in pancreatic islets, and intermediate acinar A and acinar B cells in intact frog pancreas.  相似文献   
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Light-induced alkalinization of the extracellular medium was found to be a common feature of the primary photosynthetic process of several marine microalgae. The light-induce PH increase of suspensions of whole cells was immediately and severely inhibited by a single dose of water-soluble components from crude and fuel oils. Differential effects on the rates of microalgal photosynthetic O2 evolution and cell suspension pH increase suggest different toxicity mechanisms of the water-soluble components of no. 2 fuel oil as compared with Southern Louisiana and Jay Crude oils. These short-term studies on the nature of sublethal petroleum toxicity to microalgae indicate that the primary effect may be through direct action on the energy-yielding electron transport systems.  相似文献   
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Whole cells of Micrococcus luteus (formerly Sarcina lutea ATCC 9341) have been covalently linked to a carboxymethylcellulose support system, with the retention of histidine ammonia-lyase activity. The dependence of the rate of urocanic acid formation on pH, temperature, and added surfactant concentration was similar for the free and the immobilized cells. The immobilization procedure used is based on the carbodiimide activation of carboxymethylcellulose and has been optimized for the histidine ammonia-lyase activity of the immobilized cells on a given weight of cellulose. In a column reactor at 23 degrees C and superficial velocity of 0.044 cm/min, 5 g of cellulose with bound cells gave a 35% conversion of an L-histidine solution (0.25M, pH 9.0) to urocanic acid for 16 days of continuous operation. The scope of this carbodiimide assisted immobilization procedure has been investigated for a series of microorganisms and a variety of carboxylate functionalized supports.  相似文献   
249.
The level of cyclic 3',5'-adenosine monophosphate (cAMP) in human platelets and the activity of platelet adenylate cyclase in response to prostaglandin E1 stimulation do not change during two days storage at room temperature in ACD solution. However, the level of cyclic AMP is lower in platelets stored in ACD solution than in platelets from blood anticoagulated by ethylenediamine tetra-acetic acid.  相似文献   
250.
The distribution of constitutive heterochromatin has been examined by C-banding in two somatic cell lines, grown in vitro, from a female Microtus agrestis. One line retains one intact X chromosome together with the short arm of the other X chromosome, while the other cell line retains only the short arm of one X chromosome. Thus, each cell line has lost substantial amounts of heterochromatin from the sex chromosomes, but this material has been deleted from the cells, and not translocated to other chromosomes. Nonetheless, both cell lines continue to propagate well in vitro.  相似文献   
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