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61.
M. Nakano Y. Hoshino M. Mii 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,92(2):170-172
Hypocotyl-derived protoplasts of Dianthus barbatus that had been pretreated with iodoacetamide were fused electrically with cell suspension culture-derived protoplasts of Gypsophila paniculata that could divide to form callus but could not regenerate shoots under the culture conditions used in this study. Electrofusion-derived calli which produced shoots were selected as putative somatic hybrids, and plantlets were subsequently regenerated from 2 of these selected calli. These plantlets, which in vitro produced flowers precociously, were identified as intergeneric somatic hybrids by nuclear ribosomal DNA analysis. Normal plants have not been established up to the present. 相似文献
62.
Phorbol ester induces the rapid processing of cell surface heparin-binding EGF-like growth factor: conversion from juxtacrine to paracrine growth factor activity. 总被引:18,自引:1,他引:17 下载免费PDF全文
K Goishi S Higashiyama M Klagsbrun N Nakano T Umata M Ishikawa E Mekada N Taniguchi 《Molecular biology of the cell》1995,6(8):967-980
Vero cell heparin-binding epidermal growth factor-like growth factor (HB-EGF) is synthesized as a 20- to 30-kDa membrane-anchored HB-EGF precursor (proHB-EGF). Localization and processing of proHB-EGF, both constitutive and 12-O-tetradecanoylphorbol 13-acetate (TPA)-inducible, was examined in Vero cells overexpressing recombinant HB-EGF (Vero H cells). Flow cytometry and fluorescence immunostaining demonstrated that Vero cell proHB-EGF is cell surface-associated and localized at the interface of cell to cell contact. Cell surface biotinylation and immunoprecipitation detected a 20- to 30-kDa heterogeneous proHB-EGF species. Vero H cell surface proHB-EGF turned over constitutively with a half-life of 1.5 h. Some of the 20- to 30-kDa cell surface-associated proHB-EGF was processed and a 14-kDa species of bioactive HB-EGF was released slowly, but most of the proHB-EGF was internalized, displaying a diffuse immunofluorescent staining pattern and accumulation of proHB-EGF in endosomes. Addition of TPA induced a rapid processing of proHB-EGF at a Pro148-Val149 site with a half-life of 7min. The TPA effect was abrogated by the protein kinase C inhibitors, staurosporine and H7. Kinetic analysis showed that loss of cell surface proHB-EGF is maximal at 30 min after addition of TPA and that proHB-EGF is resynthesized and the initial cell surface levels are regained within 12-24 h. Loss of cell surface proHB-EGF was concomitant with appearance of 14- and 19-kDa soluble HB-EGF species in conditioned medium. Vero H cell-associated proHB-EGF is a juxtacrine growth factor for EP170.7 cells in coculture. Processing of proHB-EGF resulted in loss of juxtacrine activity and a simultaneous increase in soluble HB-EGF paracrine mitogenic activity. It was concluded that processing regulates HB-EGF bioactivity by converting it from a cell-surface juxtacrine growth factor to a processed, released soluble paracrine growth factor. 相似文献
63.
Purification and characterization of periplasmic alpha-amylase from Xanthomonas campestris K-11151. 下载免费PDF全文
J Abe N Onitsuka T Nakano Y Shibata S Hizukuri E Entani 《Journal of bacteriology》1994,176(12):3584-3588
Xanthomonas campestris K-11151, isolated from soil, produced a periplasmic alpha-amylase of a new type. The enzyme was purified to homogeneity, as shown by several criteria. The purified enzyme showed almost the same activities on alpha-, beta-, and gamma-cyclodextrins, soluble starch, and amylose. Moreover, it was active on branched cyclodextrins, pullulan, and maltose but not on glycogen. Kinetic analysis showed that alpha-cyclodextrin was the best substrate among the cyclodextrins. The substrate specificity suggested that this enzyme had the combined activities of alpha-amylase, cyclodextrinase, and neopullulanase. 相似文献
64.
Seasonal changes in the spermatogenic epithelium of adult Japanese macaques (Macaca fuscata fuscata)
Tomoo Enomoto Kiyoaki Matsubayashi Yasukazu Nagato Mayumi Nakano 《Primates; journal of primatology》1994,35(4):465-472
A histological study was undertaken to clarify seasonal changes in the spermatogenic epithelium of Japanese macaques. Testicular
tissue samples were excised by biopsies from five adult laboratory-maintained males in mating and non-mating seasons. The
samples were fixed with Bouin's solution, embedded in paraffin, and stained with PAS and hematoxylin. Microscopic observations
on cross-sections of seminiferous tubules revealed that the seminiferous epithelium in the mating season was thicker than
in the non-mating season. PAS-stained granules were found in some of the dark A-type spermatogonia, which significantly increased
in the non-mating season. Spermatids of the steps preceding the appearance of the acrosomic cap in stages I to III were observed
significantly more often than those in the step coinciding with the formation of the acrosomic cap in stage IV. In stage I,
the ratio of mature spermatids or spermatozoa to immature spermatids in the mating season was higher than that in the non-mating
season. These findings suggest that spermiogenesis, as well as spermatocytogenesis, is inhibited in the non-mating season. 相似文献
65.
Salvelinus leucomaenis (white-spotted charr) and S. malma (Dolly Varden) are distributed throughout Hokkaido Island, Japan, but sites where they occur in sympatry are rare. In general, S. malma inhabit upstream reaches and S. leucomaenis extend downstream to the ocean. Factors influencing their distribution were analyzed at four spatial scales ranging from the whole island to individual stream pools. At the island scale, S. leucomaenis were found in the warmer south-west region and at lower altitudes elsewhere, whereas S. malma were found in the colder north-east and at higher altitudes. At a regional scale, the downstream limit of S. malma and upstream limit of S. leucomaenis shifted to lower altitude from south-west to north-east across the island, coincident with the decrease in temperature. Further analysis showed that transition points from S. leucomaenis or sympatry to S. malma in individual watersheds were closely related to an index of cumulative mean monthly temperatures exceeding 5°C. However, at the scale of a single watershed, the transition occurred at different altitudes, gradients, and temperatures in two tributaries, apparently because stream discharge, habitat, and disturbances from floods interacted with these abiotic factors to limit distribution. The two charr species developed interspecific dominance hierarchies in individual pools, and there was strong complementary density compensation among stream pools that could be explained by interspecific competition but not by differences in habitat. However, patterns at watershed and regional scales suggested that interspecific competition interacts with temperature in complex ways. We conclude that the importance of various abiotic and biotic factors in shaping Hokkaido charr distributions depends on the scale at which they are viewed. 相似文献
66.
Tetsuya Oguma Asahi Matsuyama Mamoru Kikuchi Eiichi Nakano 《Applied microbiology and biotechnology》1993,39(2):197-203
The gene for cyclomaltodextrinase (CDase; EC 3.2.1.54) from Bacillus sphaericus E-244 was cloned in the recombinant plasmid pCD629. Sequencing a portion of pCD629 revealed a unique open reading frame of 1,773 nucleotides coding for a 591-amino-acid polypeptide. The deduced polypeptide sequence showed about 50% homology with that of a neopullulanase, and was slightly homologous to those of the cyclodextrin glucanotransferases and the -amylases. The optimum pH, specific activity and K
m value for -cyclodextrin of the CDase that has been produced in Escherichia coli cells were 8.0, 16.4 units/mg protein, and 0.41 mm, respectively. These values were almost identical to those from B. sphaericus E-244.
Correspondence to: T. Oguma 相似文献
67.
68.
Inhibition of endoplasmic reticulum (ER)-to-Golgi transport induces relocalization of binding protein (BiP) within the ER to form the BiP bodies. 总被引:11,自引:6,他引:5 下载免费PDF全文
Immunofluorescence staining of yeast cells with anti-binding protein (BiP) antibodies shows uniform staining of the endoplasmic reticulum (ER). We have found that overproduction of Sec12p, an ER membrane protein, causes a change of BiP distribution within the cell. Upon induction of Sec12p by the GAL1 promoter, the staining pattern of BiP turns into bright dots scattering in the cell, whereas the staining of Sec12p remains to be the typical ER figure. Overproduction of other ER membrane proteins, HMG-CoA reductase or Sed4 protein, does not induce such relocalization of BiP. Pulse-chase experiments and electron microscopy have revealed that the overproduction of Sec12p inhibits protein transport from the ER to the Golgi apparatus. When the transport is arrested by one of the sec mutations that block the ER-to-Golgi step at the restrictive temperature, the BiP staining also changes into the punctate pattern. In contrast, the sec mutants that block later or earlier steps of the secretory pathway do not induce such change of BiP localization. These observations indicate that relocalization of BiP is caused by the inhibition of ER-to-Golgi transport. Using immunoelectron microscopy, we have found that the punctate staining is because of the accumulation of BiP in the restricted region of the ER, which we propose to call the "BiP body." This implicates existence of ER subdomains in yeast. A vacuolar protein, proteinase A, appears to colocalize in the BiP body when the ER-to-Golgi transport is blocked, suggesting that the BiP body may have a role as the site of accumulation of cargo molecules before exit from the ER. 相似文献
69.
Nitric Oxide Reversibly Suppresses Xanthine Oxidase Activity 总被引:10,自引:0,他引:10
Masami Fukahori Kohji Ichimori Hideyuki Ishida Hiroe Nakagawa Haruka Okino 《Free radical research》1994,21(4):203-212
The effects of nitric oxide (NO) on xanthine oxidase (XOD) activity and the site(s) of the redox center(s) affected were investigated. XOD activity was determined by superoxide (O2-) generation and uric acid formation. NO reversibly and dose-dependently suppressed XOD activity in both determination methods. The suppression interval also disclosed a dose-dependent prolongation. The suppression occurred irrespective of the presence or absence of xanthine; indicating that the reaction product of NO and O2-, peroxynitrite, is not responsible for the suppression. Application of synthesized peroxynitrite did not affect XOD activity up to 2 μM. Methylene blue, which is an electron acceptor from Fe/S center, prevented the NO-induced inactivation. The results indicate that NO suppresses XOD activity through reversible alteration of the flavin prosthetic site. 相似文献
70.
Vesselina Gadzheva Kohji Ichimori Hiroe Nakazawa Zahary Raikov 《Free radical research》1994,21(3):177-186
Superoxide scavenging activities (SSA) of newly synthesized spin-labeled nitrosourea and triazene derivatives, and their precursor nitroxides were investigated by the ESR/spin-trapping method using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and hypoxanthine/xanthine oxidase as the superoxide-generating system. The spin-labeled nitrosoureas, triazenes and their precursor nitroxides exhibited excellent SSA, whereas clinically used nitrosourea and triazene, which do not contain the nitroxide moiety, did not show any SSA. Furthermore, it was deduced that these nitroxides scavenge superoxide by redox cycling between nitroxide and corresponding hydroxylamine. 相似文献