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931.
932.
Summary Na+, K+, Mg++-activated adenosine triphosphatase and K+, Mg++-activatedp-nitrophenyl phosphatase prepared from a membrane fraction of bovine cerebral cortex were studied with regard to the manner
of their activation by phospholipids, using phosphatidyl serine, lysolecithin, monodecyl and didecyl phosphates. The kinetic
and chromatographic studies suggested the following. (1) When the enzyme proteins bind the phospholipids in a proper ratio,
they attain the optimum activation. (2) The binding causes a simple conversion of the enzymes from an inactive form to a fully
activated form. (3) The lipids in both micellar form and molecular dispersion activate the enzymes. (4) Of the proteins contained
in the enzyme preparation, only a group of proteins possessing the ATPase and the phosphatase activities bind phospholipids,
and the amount of the bound lipids is limited. 相似文献
933.
934.
Ryo Tanaka 《Population Ecology》1962,4(1):8-16
Summary The vole,Eothenomys smithi, in highlands of Shikoku was studied to disclose ups and downs of adrenal activities under the influence of the breeding
level in natural populations. It has proved that the vole's adrenal in both sexes may be much more strongly by rise and fall
of the fertility as well as by shift of the age structure in populations than the rat's. Therefore, as for perhaps all kinds
of small mammals, we consider necessary to follow a pertinent procedure to avoid thoroughly these sources of error in studies
to draw any conclusion for or against theChristian's theory. The present data analysed by such a method failed to afford any confirmative proofs; the fact that the pregnancy
rate was increased in parallell to the density is against his view. However, never the whole content of the theory has been
invalidated by these results. 相似文献
935.
936.
In order to elucidate the biological role of minor lymphocyte stimulating (Mls) gene products, we have been investigating the fundamental immunogenetic characteristics of the Mls system. In this report, describe the distribution of stimulatory Mls products, Mlsa and Mlsc, in a panel of laboratory inbred strains based on the response pattern of H-2-compatible naive T-cell populations as well as monospecific Mlsa- or Mlsc-reactive T-cell clones. In addition, the expression of four different T-cell receptor (Tcr) b-V segment Tcrb-V3, –V6, –V8.1, and –V9, which were recently reported to be associated with T-cell recognition of Mls gene products in these strains, was examined. The results indicate that the majority of commonly used laboratory strains including those originally typed as Mls
aare also expressing Mlsc determinants and that very few independent inbred strains are non-Mls
c. Moreover, the pattern of Tcrb-V expression in spleen as well as in thymus suggests that the association between Mls expression and clonal deletion of self Mls-reactive T cells appears to be the general rule in inbred strains. Based on these results, implications for the nondetectable Mls-like gene products in other species besides the mouse are discussed. 相似文献
937.
Summary We have established a unique betalain pigmentation system in callus cultures that originated from seedlings of Portulaca sp. Jewel. Within three different Jewel lines examined, one line (JR) was clearly superior with regard to callus growth rate and pigment formation. Furthermore, after ten cycles of selection of deeply colored callus patches, the selected clones contained on an average four times the amount of betalain as compared to the non-selected mother line. The colorization was induced by light, but disappeared in the dark. Pigment synthesis was detectable within 30 h after irradiation and showed positive correlation with irradiation periods.Abbreviations 2,4-D
2,4-dichlorophenoxy-acetic acid
- HPLC
high performance liquid chromatography 相似文献
938.
S Watanabe N Nakayama T Yokota K Arai A Miyajima 《Current opinion in biotechnology》1991,2(2):227-237
Cytokines play a vital role in coordinating immune and inflammatory responses. As many cytokine gene hunters have begun to focus their efforts on receptors, novel aspects of hemopoietic growth factor receptors have emerged. Two types of growth factor receptors have been classified--the cytokine receptor family and growth factor receptor family with tyrosine kinase activity. The two types of receptors may have unique roles in 'inducible' and 'constitutive' hemopoiesis which are controlled by immunological stimuli and by interaction with stromal cells, respectively. 相似文献
939.
Hiroyuki Sugimoto Koei Hamana Shigeru Matsuzaki Takayuki Arai Shoji Yamada 《The Journal of steroid biochemistry and molecular biology》1991,38(6):781-786
Previously we reported that administration of lipopolysaccharide (LPS) to mice increased the hepatic levels of putrescine (PUT) and N1-acetylspermidine (N1-acetyl-SPD). In the current study, we examined the in vivo effects of some steroid hormones on the LPS-induced increase in PUT and N1-acetyl-SPD. Corticosterone, hydrocortisone and dexamethasone suppressed the LPS-induced increase in PUT and N1-acetyl-SPD in mouse liver in a dose-dependent manner, dexamethasone being the most effective among them. On the other hand, oesterone and oestradiol-17β enhanced the LPS-induced increase in PUT and N1-acetyl-SPD in a dose-dependent manner. Oestradiol-17 and 16β-ethyl-oestradiol, as an inactive oestradiol isomer and an antioestrogen, respectively, likewise enhanced the increase in PUT and N1-acetyl-SPD concentrations induced by LPS. 16-hydroxy-oestradiol (oestriol), 16-hydroxyestrone, 2-hydroxyoestradiol, 2-hydroxyoestrone, progesterone, testosterone, diethylstilboestrol and nonsteroidal antioestrogen such as tamoxifen and nafoxidine had no effect on the increase. Oestradiol-17β enhanced and corticosterone had little on the carbon tetrachloride-induced increase in PUT and N1-acetyl-SPD. These results suggest that glucocorticoids suppress the increase by preventing the immunological injury by Kupffer cells on hepatocytes and that the stimulatory effect of oestrogens may not be associated with their oestrogenic activities mediated by the oestrogen receptor system. 相似文献
940.
N Márquez-Sterling I M Herman T Pesacreta H Arai G Terres M Forgac 《European journal of cell biology》1991,56(1):19-33
Proton-translocating ATPases of the vacuolar class (V-ATPases) are found in a variety of animal cell compartments that participate in vesicular membrane transport, including clathrin-coated vesicles, endosomes, the Golgi apparatus, and lysosomes. The exact structural relationship that exists among the V-ATPases of these intracellular compartments is not currently known. In the present study, we have localized the V-ATPase by light and electron microscopy, using monoclonal antibodies that recognize the V-ATPase present in clathrin-coated vesicles. Localization using light microscopy and fluorescently labeled antibodies reveals that the V-ATPase is concentrated in the juxtanuclear region, where extensive colocalization with the Golgi marker wheat germ agglutinin is observed. The V-ATPase is also present in approximately 60% of endosomes and lysosomes fluorescently labeled using alpha 2-macroglobulin as a marker for the receptor-mediated endocytic pathway. Localization using transmission electron microscopy and colloidal gold-labeled antibodies reveals that the V-ATPase is present at and near the plasma membrane, alone or in association with clathrin. These results provide evidence that the V-ATPases of plasma membrane, endosomes, lysosomes, and the Golgi apparatus are immunologically related to the V-ATPase of clathrin-coated vesicles. 相似文献