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11.
Aplopsora corni sp. nov. is proposed for a rust fungus whose uredinial and basidial stage occurs onCornus controversa (Cornaceae) in Hokkaido. This new species is separated by its larger urediniospores and probasidia from the morphologically
closely relatedA. nyssae onNyssa aquatica andN. sylvatica (Cornaceae) distributed in southern North America. 相似文献
12.
13.
Masakane Yamashita Jianqiao Jiang Hiroshi Onozato Teruyuki Nakanishi Yoshitaka Nagahama 《Development, growth & differentiation》1993,35(6):631-636
A triploid crucian carp, ginbuna ( Carassius auratus langsdorfii ), reproduces by gynogenesis, in which sperm of diploid ginbuna or of other species triggers the development of the triploid eggs, but a male genome makes no contribution to the zygotic genome. Gynogenesis is maintained by two mechanisms: exclusion of male genome during fertilization and retention of somatic ploidy levels during oogenesis. We examined the mechanisms responsible for producing unreduced eggs. Microfluorometry with a DNA staining dye showed that DNA content in the ginbuna oocytes was not reduced in half during meiosis I. Cytological observations revealed that a tripolar spindle was formed at meiosis I and the first polar body was not extruded, whereas an ordinary bipolar spindle was formed and the second polar body was extruded at meiosis II. Activity of histone H1 kinase (as an indicator of maturation-promoting factor) decreased transiently between meiosis I and II, strongly suggesting a "normal" meiotic cycle progression in the ginbuna oocytes. These results have indicated that in the gynogenetic ginbuna the somatic ploidy levels are maintained by inhibiting the first polar body extrusion via the formation of the tripolar spindle at meiosis I. 相似文献
14.
Acetyl-CoA cleavage pathway in a syntrophic propionate oxidizing bacterium growing on fumarate in the absence of methanogens 总被引:4,自引:0,他引:4
Yoshitaka Kuriki 《FEMS microbiology letters》1993,110(1):71-76
Abstract In an ompF'-'lacZ fusion system carried by the open reading frame vector pORF1 in a supE mutant of Escherichia coli K12, read-through of an amber codon was decreased at temperatures higher than 40°C. This effect of temperature was dependent on the nucleotide sequence surrounding the amber codon, which was inserted into a site between the ompF and lacZ cistrons. Upon a temperature shift-up from 30 to 42°C, β-galactosidase synthesis directed by this fusion showed a transient arrest. 相似文献
15.
Yoshihiro Kuroda Yoshitaka Maeda Shinichi Sawa Kiyohiro Shibata Kazuhide Miyamoto Terumichi Nakagawa 《Journal of peptide science》2003,9(4):212-220
Pathogenic prion proteins (PrP(Sc)) are thought to be produced by alpha-helical to beta-sheet conformational changes in the normal cellular prion proteins (PrP(C)) located solely in the caveolar compartments. In order to inquire into the possible conformational changes due to the influences of hydrophobic environments within caveolae, the secondary structures of prion protein peptides were studied in various kinds of detergents by CD spectra. The peptides studied were PrP(129-154) and PrP(192-213); the former is supposed to assume beta-sheets and the latter alpha-helices, in PrP(Sc). The secondary structure analyses for the CD spectra revealed that in buffer solutions, both PrP(129-154) and PrP(192-213) mainly adopted random-coils (approximately 60%), followed by beta-sheets (30%-40%). PrP(129-154) showed no changes in the secondary structures even in various kinds of detergents such as octyl-beta-D-glucopyranoside (OG), octy-beta-D-maltopyranoside (OM). sodium dodecyl sulfate (SDS), Zwittergent 3-14 (ZW) and dodecylphosphocholine (DPC). In contrast, PrP(192-213) changed its secondary structure depending on the concentration of the detergents. SDS, ZW, OG and OM increased the alpha-helical content, and decreased the beta-sheet and random-coil contents. DPC also increased the alpha-helical content, but to a lesser extent than did SDS, ZW, OG or OM. These results indicate that PrP(129-154) has a propensity to adopt predominantly beta-sheets. On the other hand, PrP(192-213) has a rather fickle propensity and varies its secondary structure depending on the environmental conditions. It is considered that the hydrophobic environments provided by these detergents may mimic those provided by gangliosides in caveolae, the head groups of which consist of oligosaccharide chains containing sialic acids. It is concluded that PrP(C) could be converted into a nascent PrP(Sc) having a transient PrP(Sc) like structureunder the hydrophobic environments produced by gangliosides. 相似文献
16.
17.
Fumi Katoh Kazuo Kitamura Hiromi Niina Ryuichi Yamamoto Hisanori Washimine †Kenji Kangawa Yoshitaka Yamamoto Hideyuki Kobayashi Tanenao Eto Akihiko Wada 《Journal of neurochemistry》1995,64(1):459-461
Abstract: In cultured bovine adrenal medullary cells, stimulation of nicotinic receptors by carbachol evoked the Ca2+ -dependent exocytotic cosecretion of proadrenomedullin N-terminal 20 peptide (PAMP) (EC50 = 50.1 µ M ) and catecholamines (EC50 = 63.0 µ M ), with the molar ratio of PAMP/catecholamines secreted being equal to the ratio in the cells. Addition of PAMP[1–20]NH2 inhibited carbachol-induced 22 Na+ influx via nicotinic receptors (IC50 = 2.5 µ M ) in a noncompetitive manner and thereby reduced carbachol-induced 45 Ca2+ influx via voltage-dependent Ca2+ channels (IC50 = 1.0 µ M ) and catecholamine secretion (IC50 = 1.6 µ M ). It did not alter high K+ -induced 45 Ca2+ influx via voltage-dependent Ca2+ channels or veratridine-induced 22 Na+ influx via voltage-dependent Na+ channels. PAMP seems to be a novel antinicotinic peptide cosecreted with catecholamines by a Ca2+ -dependent exocytosis in response to nicotinic receptor stimulation. 相似文献
18.
Toshinobu Tokumoto Masakane Yamashita Mika Tokumoto Yoshinao Katsu Ryo Horiguchi Hiroko Kajiura Yoshitaka Nagahama 《The Journal of cell biology》1997,138(6):1313-1322
Immediately before the transition from metaphase to anaphase, the protein kinase activity of maturation or M-phase promoting factor (MPF) is inactivated by a mechanism that involves the degradation of its regulatory subunit, cyclin B. The availability of biologically active goldfish cyclin B produced in Escherichia coli and purified goldfish proteasomes (a nonlysosomal large protease) has allowed the role of proteasomes in the regulation of cyclin degradation to be examined for the first time. The 26S, but not the 20S proteasome, digested recombinant 49-kD cyclin B at lysine 57 (K57), producing a 42-kD truncated form. The 42-kD cyclin was also produced by the digestion of native cyclin B forming a complex with cdc2, a catalytic subunit of MPF, and a fragment transiently appeared during cyclin degradation when eggs were released from metaphase II arrest by egg activation. Mutant cyclin at K57 was resistant to both digestion by the 26S proteasome and degradation at metaphase/anaphase transition in Xenopus egg extracts. The results of this study indicate that the destruction of cyclin B is initiated by the ATP-dependent and ubiquitin-independent proteolytic activity of 26S proteasome through the first cutting in the NH2 terminus of cyclin (at K57 in the case of goldfish cyclin B). We also surmise that this cut allows the cyclin to be ubiquitinated for further destruction by ubiquitin-dependent activity of the 26S proteasome that leads to MPF inactivation. 相似文献
19.
I. Szumiel M. Kapiszewska M. Kruszewski T. Iwaneńko C. S. Lange 《Radiation and environmental biophysics》1995,34(2):113-119
Cells from the L5178Y murine lymphoma subline LY-R are twice as resistent to killing by ionizing radiation than the subline LY-S. In contrast, LY-R cells are more sensitive to killing by H2O2, the effect being more pronounced at 37 °C than 0 °C. Initial DNA damage after H2O2 treatment (both temperatures, 5 min) has been estimated by the comet assay (single-cell gel electrophoresis) and fluorescent halo technique. According to both methods, the initial damage is significantly higher in LY-R cells, particularly that inflicted at O °C. Differences between DNA unwinding and rewinding abilities at pH 9 and 6.9 (estimated by the fluorescent halo technique) point to a considerable difference in pH-9-labile damage between the sublines, as observed previously for x-irradiated cells (Kapiszewska et al. 1992). In contrast to findings with x-irradiated cells, however, after H2O2 treatment this damage is more extensive in LY-R cells than in LY-S cells. Thus, the initial pH-9-labile damage corresponds to the pattern of sensitivity to H2O2 and x-rays. We suggest that this is caused by different proportions of cuprous and ferric ions found in the nuclei of LY sublines and by the different ability of these ions to react with H2O2 and water radiolysis products. The copper/iron ratio in the nucleus is 1.31 in LY-R cells and 4.84 in LY-S cells. 相似文献
20.
Takehiko Watanabe Yoshitaka Taguchi Yukihiko Kitamura Kenichiro Tsuyama Hirota Fujiki Hiroshi Tanooka Takashi Sugimura 《Biochemical and biophysical research communications》1982,109(2):478-485
The effects of various promoters in two-step carcinogenesis on the induction of histidine decarboxylase in the skin of mice was investigated. The potencies of various phorbol esters in inducing histidine decarboxylase activity were parallel with their tumor-promoting activities. Indole alkaloids such as dihydroteleocidin B and lyngbyatoxin A, which induced ornithine decarboxylase and promoted tumor development in the skin of mice with the same potency as 12-O-tetradecanoylphorbol-13-acetate (TPA), also induced histidine decarboxylase activity. These results suggest that histamine produced by this inducible histidine decarboxylase may play some role in tumor promotion. 相似文献