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61.
Expression of activities of two 20 alpha-hydroxysteroid dehydrogenase isozymes in rat corpora lutea.
H H Seong K Shiota K Noda A Ogura T Asano M Takahashi 《Journal of reproduction and fertility》1992,96(2):573-580
The rat ovary contains two isozymes of 20 alpha-hydroxysteroid dehydrogenase (HSD-1 and HSD-2). In this study, the expression of activity of each isozyme was investigated in ovaries that contained a single generation of corpora lutea during pseudopregnancy. This condition was induced by cervical stimulation in rats that had been rendered anovulatory by housing them in a continuously lit environment. The total activity of cytosolic 20 alpha-HSD was lower in the ovaries of these pseudopregnant rats than in ovaries containing multiple generations of corpora lutea. In normal pseudopregnancy, HSD-1 activity was low on days 5 and 9 and increased markedly on day 15, whereas HSD-2 was lower than HSD-1 and did not vary throughout pseudopregnancy. However, on days 5 and 9 of continuous-light pseudopregnancy, low activity of HSD-1 only was detected; by day 15, HSD-1 activity had increased sixfold and HSD-2 activity could be detected. Immunohistochemical methods using a specific antibody recognizing both HSD-1 and HSD-2 revealed that the number of 20 alpha-HSD-positive luteal cells increased by day 15. Thus, the increase in total enzyme activity and appearance of HSD-2 activity observed at late pseudopregnancy was accompanied by an increase in the number of 20 alpha-HSD-positive luteal cells. 相似文献
62.
K Yamanouchi S Matsuyama M Nishihara K Shiota C Tachi M Takahashi 《Biology of reproduction》1992,46(6):1109-1113
The effect of splenic macrophages on in vitro progestin secretion (the sum of the progesterone and 4-pregnen-20 alpha-ol-3-one concentrations in the medium) from mature rat granulosa cells was examined by means of co-culture techniques. When splenic macrophages (3.0 x 10(5) cells/ml) obtained from adult female rats on the evening of proestrus (1800 h) were added to granulosa cells (1.5 x 10(5) cells/ml) and co-cultured for 96 h in the absence of prolactin (PRL), progestin secretion from granulosa cells did not change. However, co-culture of granulosa cells with the macrophages in the presence of PRL (2 micrograms/ml) significantly enhanced progestin secretion after 48 h of culture. This stimulatory effect on progestin secretion was observed only when the number of macrophages added was more than twice the number of granulosa cells. On the other hand, splenic macrophages obtained on the evening of diestrus had no effect on progestin secretion from granulosa cells even in the presence of PRL. These results suggest that splenic macrophages can enhance PRL action so as to stimulate progestin secretion from granulosa cells and that this function of splenic macrophages varies during the estrous cycle. 相似文献
63.
Explanted palates of day 12 and day 13 mouse fetuses were cultured in a chemically defined serumless medium for 48-72 h by a suspension culture technique. The palate of day 12 fetuses closed successfully within 72 h and that of day 13 fetuses within 48 h. Both macroscopically and histologically, the in vitro fusion of palatal shelves simulated the palatogenetic process in vivo. This novel technique for culturing the fetal mouse palate may be of potential use for the study of palatogenesis and in developmental toxicology. 相似文献
64.
The enzyme activity of dephosphorylation of thymidine triphosphate was found in microsomal fraction of rat liver. The enzyme activity decreased at the time when [3H]thymidine incorporation into DNA of regenerating liver increased. When the [3H]thymidine incorporation was suppressed by 1,3-diaminopropane, the enzyme activity remained elevated. These results suggest that the enzyme activity appears to be closely linked to DNA synthesis. 相似文献
65.
Nobuhiko Suzuki Yasuhisa Kunimi Seiji Uematsu Ken’ichi Kobayashi 《Population Ecology》1980,22(2):273-283
Summary The changes in spatial distribution pattern during larval stage of the fall webworm,Hyphantria cunea were quantitatively investigated in the field experimental populations.
The female adult deposits eggs as a cluster and the hatchlings make a compact colonial-web. In this period, the all-or-none
type mortality which is characteristic in gregarious insect species was occasionary recognized before spinning a compact colonial-web.
Once making a compact colonial-web, the larvae feed the leaves in the colonial-web up to about 5th instar. In this period,
the movement of larvae occurred due to the local food shortage in a colonial-web and the expansion of colonial-web. As the
larvae developed, the colonial-web was separated into several small groups. These larvae began to disperse about 5th instar.
In this period, the local food shortage seems to be an important trigger for the larval dispersal. The mean concentration
of larvae on leaves abruptly decreased, and finally the larvae became solitary at the 6th or 7th instars.
The dispersal process in later larval stage is not necessarily due to the complete food shortage. The dispersal prior to the
occurrence of food shortage may be a safety mechanism to protect the larvae from the food shortage. 相似文献
66.
Seiji Suzuki Hiroshi Oka Hiroko Yasuda Masahiro Ikeda Po Yuan Cheng Toshitsugu Oda 《Biochemical and biophysical research communications》1981,99(3):987-993
Isolated rat pancreatic islets, incubated in the presence of extracellular 32Pi to steady state 32P incorporation into cellular phosphopeptides, were exposed to glucose for 10 min. Glucose (16.7 mM) significantly stimulated the phosphorylation of six phosphoproteins with molecular weights of 15,000, 35,000, 49,000, 64,000, 93,000 and 138,000. Mannoheptulose (16.7 mM) markedly inhibited glucose-stimulated phosphorylation of these six phosphoproteins. This protein phosphorylation might be important in mediating glucose-stimulated insulin release. 相似文献
67.
The oxidative cleavage of folates. A critical study 总被引:1,自引:0,他引:1
Alkaline permanganate oxidation has been used to determine the chain length of naturally occurring pteroylpolyglutamates on the assumption that all forms of folates cleave at the C9N10 bond to produce the corresponding p-aminobenzoyl-polyglutamates. The chain length of the latter could be determined by cochromatography with synthetic markers. The products of alkalinc (ammonium bicarbonate buffer, pH 9.0) permanganate oxidation of a number of reduced and oxidized, one-carbon-substituted and unsubstituted folic acid derivatives have been identified, and their yields and stability to the oxidative treatment have been determined. Unsubstituted, oxidized and reduced folic acid and N5-formyl-tetrahydrofolic acid are cleaved at the C9N10 bond to produce p-aminobenzoylglutamic acid. N5, N10-methenyl-tetrahydrofolic acid, N5,N10-methylene-tetrahydrofolic acid, and N10-formyl-tetrahydrofolic acid are not cleaved but are oxidized to N10-formyl-folic acid which is completely stable to the oxidative treatment employed. N5-methyl-tetrahydrofolic acid is not cleaved either but is oxidized to N5-methyl-dihydrofolic acid which upon continued oxidation decomposes slowly to unidentified products. The γ-glutamyl peptide linkage is completely stable to oxidation. Using p-amino-[3,5-3H]benzoylglutamic acid, it is also shown that this product, previously thought to be stable to the oxidative treatment is decomposed by it. The significance of these findings in terms of the errors that may have been introduced in prior estimations of the chain length and pool sizes of the naturally occurring pteroylpolyglutamates is discussed. The possibility of developing a method for the chain length determination of noncleavable pools of one-carbon-substituted folates using [2-14C]folic acid to label the folates in vivo is presented. 相似文献
68.
The per(trimethylsilyl) ethers of d-glucose, d-galactose, and d-mannose were analyzed by g.l.c.-c.i.m.s. with ammonia as the reagent gas. C.i.m.s. gave simple fragmentation and fragment ions of high intensity in the high-mass range where the QM+ ion is also detected. The β-d anomers gave ions at m/e 558 showing intensities 3–12 times those of the α-d anomers. The epimers could be distinguished by differences in the intensities of the ions and by the observation that d-glucose gave a base peak at m/e 198, d-galactose at m/e 468, and d-mannose at m/e 204. The pyranose and furanose structures could be distinguished by comparing the ion intensities at m/e 198, m/e 271, m/e 361, m/e 396, and m/e 451. A similar analysis was also performed with 2-methylpropane as the reagent gas. 相似文献
69.
Virulence of Streptococcus mutans: biochemical and pathogenic characteristics of mutant isolates. 总被引:23,自引:0,他引:23
S M Michalek T Shiota T Ikeda J M Navia J R McGhee 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1975,150(2):498-502
The in vitro dextran-sucrase activities and adherence to glass of S. mutans 6715 and PS14 wild types and mutants were quantitated and compared with their in vivo cariogenicity in young, gnotobiotic rats. In general, S. mutans PS14 mutants B414 and B421 and 6715 mutant C4 demonstrated less dextran-sucrase activity and adherence than parental strains and caused fewer carious lesions in gnotobiotic rats. Rats monoinfected with either PS14 mutants B414 or B421 had less plaque and viable S. mutans in plaque than rats infected with parental strain. Both S. mutans 6715 mutants C211 and C229, demonstrated greater enzyme activity and adherence than the parental strain and produced more carious lesions. 相似文献
70.
The injurious effect of pisatin on the plasma membrane of pea 总被引:4,自引:0,他引:4
Shiraishi Tomonori; Oku Hachiro; Isono Mitsuko; Ouchi Seiji 《Plant & cell physiology》1975,16(5):939-942
The main cause of wilting which occurs in pea leaves heavilyinfected with powdery mildew was suggested to be due to theinjurious effect of pisatin, a defensive antifungal substanceproduced by the host leaves, which affects the plasma membraneof the same host cells. (Received May 29, 1975; ) 相似文献