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31.
Masami Matsumoto Yukihiro Shoyama Itsuo Nishioka Hisashi Iwai Satoshi Wakimoto 《Plant cell reports》1989,7(8):636-638
Virus free plants of Rehmannia glutinosa Libosch. var. purpurea Makino were obtained through meristem tip tissue cultures from plants infected with a mixture of tabocco mosaic virus(TMV), a member of the carlavirus group, and an unknown spherical virus. The re-infection rate of the virus free plants by TMV in the field was determined by enzyme linked immunosorbent assay(ELISA). Twenty seven percent of the plants were re-infected during the first year, 31 % by the end of second year, and 63 % by the end of the third year. The yield of root and iridoid glycoside contents gradually decreased each year. These results led to the conclusion that virus infection causes marked decrease of the yield of roots and productivity of secondary metabolites. 相似文献
32.
33.
N Funata M Fukayama K Sugano M Koike 《The journal of histochemistry and cytochemistry》1989,37(3):287-292
To identify and characterize the subcellular topography of glycine-extended pro-gastrin-processing intermediates (G-Gly) in human antral mucosa, we performed an electron microscopic immunocytochemical study using region-specific antisera generated against the synthetic peptide, Tyr-Gly-Trp-Met-Asp-Phe-Gly (GL7), and C-terminal-specific anti-gastrin antisera. As has been previously reported, G-cells contained both electron-dense and electron-lucent granules, with a range of intermediate forms. Gastrin immunoreactivity was demonstrated in almost all granules of each type, whereas anti-GL7 antisera immunostained chiefly electron-dense granules. The relative ratio of GL7/gastrin granules varied among different cells but was approximately 1:10 on average. Other cytoplasmic organelles were devoid of specific labeling for GL7 or gastrin. As we have assumed that G-Gly serves as the immediate precursor for each molecular form of gastrin, electron-dense granules with high labeling for GL7 are regarded as the principal site for conversion of G-Gly to gastrin. This speculation supports many previous reports that electron-dense granules are immature and that the granules become less electron-dense with maturation. 相似文献
34.
The usefulness of the micronucleus assay for investigating the radiation response of hepatocytes was examined. The frequency was defined as the ratio of the total number of micronuclei to the number of hepatocytes examined. The dose-response curves were curvilinear after X rays and linear after neutrons. These dose-response curves were analyzed by a linear-quadratic model, frequency = aD + bD2 + c. The a/b ratio was 3.03 +/- 1.26 Gy following X irradiation. This value is within the range of the alpha/beta ratios reported by others using the clonogenic assay of hepatocytes. While the a/b value for neutrons was 24.3 +/- 11.7 Gy, the maximum relative biological effectiveness of neutrons was 6.30 +/- 2.53. Since the micronucleus assay is simple and rapid, it may be a good tool for evaluating the radiation response of hepatocytes in vivo. 相似文献
35.
Hillary A. Hahm Margot M. Ip Kathleen Darcy Jennifer D. Black Wendy K. Shea Suzanne Forczek Masami Yoshimura Takami Oka 《In vitro cellular & developmental biology. Plant》1990,26(8):803-814
Summary A serum-free primary culture system is described which allows normal rat mammary epithelial cells (RMECs) embedded within
a reconstituted basement membrane to undergo extensive growth and functional differentiation as detected by synthesis and
secretion of the milk products casein and lipid. RMECs isolated from mammary glands of immature virgin rats were seeded within
an extracellular matrix preparation derived from the Engelbreth-Holm-Swarm sarcoma and cultured in a serum-free medium consisting
of Dulbecco's modified Eagle's medium-F12 containing insulin, prolactin, progesterone, hydrocortisone, epidermal growth factor,
bovine serum albumin, transferrin, and ascorbic acid. Casein synthesis and secretion were documented at the electron microscopic
level as well as by an enzyme-linked immunosorbent assay (ELISA) assay using a polyclonal antibody against total rat caseins.
Numerous secretory vesicles with casein micelles were noted near the apical surface of the RMECs, and secreted casein was
observed in the lumen. These ultrastructural data were confirmed by the ELISA assay which showed that microgram amounts of
casein per well were synthesized by the RMECs and that the amount of casein increased with time in culture. Using immunoblot
analysis it was demonstrated that the full complement of casein proteins was synthesized. In addition to casein protein, β-casein
mRNA levels were shown to increase with time. Synthesized lipid was detected at both the light and electron microscopic levels.
Phase contrast photomicrographs demonstrated extensive intracellular lipid accumulation within the ductal and lobuloalveolarlike
colonies, and at the electron micrograph level, lipid droplets were predominantly localized near the apical surface of the
RMECs. The lipid nature of these droplets was verified by oil red O staining. Results from this study demonstrate that RMECs
from immature virgin rats proliferate extensively and rapidly develop the capacity to synthesize and secrete casein and lipid
when grown within a reconstituted basement membrane under defined serum-free conditions. This unique system should thus serve
as an excellent model in which the regulation of mammary development and gene expression can be investigated.
This work was supported by grants CA 33240 and CA 35641 and by core grant CA 24538 from the National Institutes of Health,
Bethesda, MD. 相似文献
36.
Changes in foliage density distribution with altitude and its effect on shoot growth and flowering were studied in forest section planes (profiles) of subalpine forests and scrubs (Krummholz) in Nepal and Japan.Patterns of foliage in forest canopy were evaluated by an analysis of variance. Foliage densities were very high at high altitude canopies, but the change in spatial patterns along altitude differs in both areas.The spatial pattern of new shoot production was similar to that of current foliage density and was affected by the amount of foliage above the sample probably through light condition. Flowering of tall trees occurred in the surface of the upper canopy, but a shrub species flowered even under tree canopies. 相似文献
37.
Takashi Kamaishi Tetsuo Hashimoto Yoshihiro Nakamura Fuminori Nakamura Shigenori Murata Norihiro Okada Ken-ichi Okamoto Makoto Shimizu Masami Hasegawa 《Journal of molecular evolution》1996,42(2):257-263
Partial regions of the mRNA encoding a major part of translation elongation factor 1 (EF-1) from a mitochondrion-lacking protozoan,Glugea plecoglossi, that belongs to microsporidians, were amplified by polymerase chain reaction (PCR) and their primary structures were analyzed. The deduced amino acid sequence was highly divergent from typical EF-1's of eukaryotes, although it clearly showed a eukaryotic feature when aligned with homologs of the three primary kingdoms. Maximum likelihood (ML) analyses on the basis of six different stochastic models of amino acid substitutions and a maximum parsimony (MP) analysis consistently suggest that among eukaryotic species being analyzed,G. plecoglossi is likely to represent the earliest offshoot of eukaryotes. Microsporidians might be the extremely ancient eukaryotes which have diverged before an occurrence of mitochondrial symbiosis.
Sequence availability: The nucleotide sequence data reported here appear in the GSDB, DDBJ, EMBL, and NCBI databases with the accession number D32139 相似文献
38.
Conversion of NfsB, a minor Escherichia coli nitroreductase, to a flavin reductase similar in biochemical properties to FRase I, the major flavin reductase in Vibrio fischeri, by a single amino acid substitution. 总被引:1,自引:1,他引:0 下载免费PDF全文
NfsB is an oxygen-insensitive nitroreductase of Escherichia coli with significant amino acid sequence homology to the major flavin reductase (FRase I) of Vibrio fischeri. Here, we show that NfsB is convertible to an FRase I-like flavin reductase three times as active as the authentic FRase I by a single amino acid substitution in the least-conserved region. 相似文献
39.
Koike Hiroyuki; Yoneyama Koichi; Kashino Yasuhiro; Satoh Kazuhiko 《Plant & cell physiology》1996,37(7):983-988
Interactions of externally added plastoquinone (PQ) derivatives(PQ0-PQ3) with the photosystem II (PSII) acceptor side wereinvestigated in PSII membrane fragments prepared from spinachby measuring the photoreduction rates of PQ derivatives at variousPQ concentrations, and the following results were obtained. From the kinetic analysis, all the PQ derivatives (PQ0-PQ3)except PQ3 were shown to accept electrons at two sites (theQB site and the PQ site) as in the case of Synechococcus vulcanusPSII particles with benzoquinone derivatives [Satoh et al. (1995)Plant Cell Physiol. 36: 597]. Affinities of PQ derivatives at the QB site increased as thelength of the isoprene side chain got longer, while those atthe PQ site were not very much different for all the PQ derivativestested in this study. The inhibitory effect of DCMU was noncompetitive, and, therefore,the affinity of PQ3 for the PQ site was determined while thatfor the QB site could not be estimated presumably due to itsfairly high affinity to the site. Based on the results obtained using PQ derivatives, the mechanismof interaction of an authentic PQ, PQ9, at the QB site is discussed. (Received May 2, 1996; Accepted July 24, 1996) 相似文献
40.
Kunio Takeda Kyoko Ogawa Masami Ohara Satoshi Hamada Yoshiko Moriyama 《The protein journal》1995,14(8):679-684
Four disulfide bridges of bovineα-lactalbumin (α-lact) were selectively reduced to obtain its derivatives with three, two, and zero disulfide bridges (designated as 3SS, 2SS, and OSSα-lact, respectively). The original helicity was almost maintained in 3SSα-lact missing only the Cys6-Cysl20 bridge. Upon the reduction of both Cys28-Cys111 and Cys6-Cys120 bridges, various changes occurred in the protein. In particular, the maximum fluorescence of 1-anilinonaphthalene-8-sulfonic acid was observed in this stage. Upon the reduction of all disulfide bridges, the hydrophobic box of the protein, formed by Trp60, Ile95, Tyr103, and Trp104, was disrupted and an internal helical structure was destroyed. The conformation of each derivative was examined mainly in a solution of sodium dodecyl sulfate. In the surfactant solution, the helicity increased from 33% to 37% in 3SSα-lact, from 26% to 31% in 2SSα-lact, and from 18% to 37% in OSSα-lact, as against from 34% to 44% in intactα-lact. On the other hand, the tryptophan fluorescence of each derivative was affected in very low surfactant concentrations, suggesting that the tertiary structure considerably changed prior to the secondary structural change in the surfactant solution. 相似文献