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981.
Rat liver pyruvate kinase is phosphorylated by calcium/calmodulin-dependent protein kinase II at serine and threonine residues in a 3-4 kDa CNBr fragment located near the amino terminus. The two sites of phosphorylation were separated by reverse-phase HPLC of a thermolysin digest. Sequence analysis established the sites of phosphorylation as follows: Leu-Arg-Arg-Ala-Ser(PO4)-Val-Ala-Gln-Leu-Thr(PO4)-Gln-Glu.  相似文献   
982.
983.
This paper describes the scale-up from 0.1 to 100 liter of the unit process based on 3-mm-diameter glass spheres for the growth of BHK monolayer cells. The production of four strains of FMD virus at the 0.1-, 10-, and 100-liter scales was examined. Cell growth was estimated from measurements of the concentration of glucose in the growth medium, while the release of virus was inferred from measuring the concentration of LDH in the culture supernatant fluid. The yields of virus at 0.1-, 1-, and 10-liter scales were similar but that from the 100-liter version was somewhat lower. The reason for this lower yield and the method used to overcome it over outlined.  相似文献   
984.
The existence of mechanical noise (MN) has been demonstrated in isolated papillary muscles of rats at rest. The mean amplitude of the MN was about 1 mg, the mean frequency 1.5 Hz (t 22 degrees C). A good agreement was found between the MN amplitude and the contracture level of the muscle. However, during long contractures, the correlation between the noise and contracture magnitude was disturbed. There was no relationship between the MN amplitude and contracture magnitude during exposures inducing metabolic alterations (hypoxia, NaCN) and upsetting the work of the sarcoplasmic reticulum (caffeine). It is believed that the MN amplitude is in a good agreement with the contracture magnitude and, therefore, with the concentration of intracellular Ca2+, if the sarcoplasmic reticulum and contractile elements of the cells are intact.  相似文献   
985.
Morphological taxonomy of simple Hyphomycetes is complicated by the frequent occurrence of pleoanamorphism. In some groups of yeast-like fungi, uncommon synanamorphs are diagnostic. Differences in conidiogenesis do not always delimit natural groups. Some nomenclatural problems are mentioned, with an emphasis on the need of neotypification. Prospects are sketched for future taxonomic research.  相似文献   
986.
In the present study we investigated the binding characteristics of estrogen and antiestrogen-receptor complexes to rabbit uterine chromatin. Activated or nonactivated estrogen receptors were partially purified by DEAE-cellulose chromatography using low (1 mM) or high (10 mM) concentrations of sodium molybdate. Activated [3H]estradiol-receptor complexes showed enhanced binding to chromatin acceptor sites unmasked by 1 M, 4 M and 6 M guanidine hydrochloride. We also examined the chromatin-binding characteristics of the estrogen receptors when bound by the high-affinity triphenylethylene antiestrogen, H1285. The acceptor site activity for the [3H]H1285-receptor complexes was markedly decreased at sites unmasked by 4 M and 6 M guanidine hydrochloride. Further, the nonactivated receptor complexes showed very low binding to deproteinized chromatin. The estrogen-receptor chromatin-acceptor sites were tissue specific and saturable. These chromatin acceptor sites differ in their affinity and capacity (number of binding sites per cell) for the estrogen- and antiestrogen-receptor complexes. Thus, we suggest that the differences in the physiological and physicochemical properties of estrogens and antiestrogens may be related to their differential interaction with uterine chromatin subfractions.  相似文献   
987.
988.
Summary Net aerial primary production and accumulation of nutrients by the grasses and nongrasses of the ground layer community of a cerrado vegetation in central Brazil were determined in burnt and unburnt areas. The net aerial primary production of the ground layer community was 327 gm–2 in the unburnt area and only 242 gm–2 in the burnt area during the first year after fire. Grasses contributed 68 to 78% of the aerial biomass of the ground layer in the unburnt area. The live biomass in the burnt and unburnt areas was comparable by the end of the first dry period after the fire. The major part of N, P and K in the aerial biomass was in the grasses. The concentration of all nutrients in the aerial biomass was generally higher in the burnt area during the first year after the fire.  相似文献   
989.
Three species of blackflies were found in emergence-trap samples taken overa period of 8 months from a second-order, forested, cold-stenothermal stream in southern Ontario. The emergence phenologies of the two common species, Prosimulium mixtum and Stegopterna mutata, are described and compared with their phenologies in other streams in North America. Hypotheses are presented for the poor faunal diversity and prolonged emergence of the two species in the stream studied. Emergence data are used to describe the pupal distribution in the stream.Wing-length measurements showed a distinct dimorphism in P. mixtum: females were larger than males. Adult size (except of P. mixtum females) varied among sampling sites in the stream and, in the case of S. mutata, this variation was time dependent.  相似文献   
990.
A T cell line specific for the chemically well-defined peptidoglycan of bacterial cell wall, disaccharide tetrapeptide, was established from Lewis rats immunized with the antigen covalently linked to the autologous rat serum albumin. The antigen specificity was examined with various analogues or derivatives of the peptidoglycan. The cell line was reactive to analogues with the COOH-terminal D-amino acid, but least reactive to those with L-amino acid as COOH terminus. Transferring of the T cell line into X-irradiated normal Lewis rats induced delayed-type hypersensitivity in an antigen specific manner.  相似文献   
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