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31.
Carotenogenic mutants ofPhycomyces, which accumulate excess β-carotene or its intermediates, always failed in zygospore development. No improvement occurred
when such mutants were mated together with a helper wild type of the same mating type against the wild type of the opposite
mating type. Addition of excess synthesized pheromone, trisporin B, also failed to improve the zygospore development, though
the mating response was significantly activated in the early stages and abundant zygophores were formed. Exceptional acceleration
of the zygospore development under these experimental conditions occurred in a regulatory albino mutant (carA), which does not accumulate excess intermediate carotenoids. Chemically- or genetically-induced ovarproduction of β-carotene
or lycopene also inhibited the zygospore development. These results imply that the zygospore development ofPhycomyces is maximal when the intracellular amount of β-carotene is optimal (=wild type), and that pheromones act mainly in the early
stages of mating, while other factors such as the cell-to-cell recognition system may also be involved in the later stages.
Intracellular accumulation of excess β-carotene or its intermediates probably disturb such later-stage factors. 相似文献
32.
Parasitic specialization ofGeotrichum candidum citrus race, the causal agent of citrus sour rot, was investigated. Of seven isolates tested for pathogenecity, all could
infect ten species of citrus fruits and edible parts of five species of noncitrus crops. Only one isolate (Ap2), isolated
from soil of an apple orchard, could infect apple fruit. 相似文献
33.
Molecular cloning of a novel mitogen-inducible nuclear protein with a Ran GTPase-activating domain that affects cell cycle progression. 总被引:8,自引:2,他引:6
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M Hattori N Tsukamoto M S Nur-e-Kamal B Rubinfeld K Iwai H Kubota H Maruta N Minato 《Molecular and cellular biology》1995,15(1):552-560
We have cloned a novel cDNA (Spa-1) which is little expressed in the quiescent state but induced in the interleukin 2-stimulated cycling state of an interleukin 2-responsive murine lymphoid cell line by differential hybridization. Spa-1 mRNA (3.5 kb) was induced in normal lymphocytes following various types of mitogenic stimulation. In normal organs it is preferentially expressed in both fetal and adult lymphohematopoietic tissues. A Spa-1-encoded protein of 68 kDa is localized mostly in the nucleus. Its N-terminal domain is highly homologous to a human Rap1 GTPase-activating protein (GAP), and a fusion protein of this domain (SpanN) indeed exhibited GAP activity for Rap1/Rsr1 but not for Ras or Rho in vitro. Unlike the human Rap1 GAP, however, SpanN also exhibited GAP activity for Ran, so far the only known Ras-related GTPase in the nucleus. In the presence of serum, stable Spa-1 cDNA transfectants of NIH 3T3 cells (NIH/Spa-1) hardly overexpressed Spa-1 (p68), and they grew as normally as did the parental cells. When NIH/Spa-1 cells were serum starved to be arrested in the G1/G0 phase of the cell cycle, however, they, unlike the control cells, exhibited progressive Spa-1 p68 accumulation, and following the addition of serum they showed cell death resembling mitotic catastrophes of the S phase during cell cycle progression. The results indicate that the novel nuclear protein Spa-1, with a potentially active Ran GAP domain, severely hampers the mitogen-induced cell cycle progression when abnormally and/or prematurely expressed. Functions of the Spa-1 protein and its regulation are discussed in the context of its possible interaction with the Ran/RCC-1 system, which is involved in the coordinated nuclear functions, including cell division. 相似文献
34.
Maurizio Pellecchia Gerhard Wider Hideo Iwai Kurt Wüthrich 《Journal of biomolecular NMR》1997,10(2):193-197
A novel 2D NMR experiment, 2D HE(NE)HGHH, is presented for the assignment ofarginine side chain 1H and 15N resonances inuniformly 15N-labeled proteins. Correlations between1H, 1Hand 1H are established on the basis of3J(15N,1H) heteronuclear scalarcoupling constants, and sequence-specific assignments are obtained by overlapof these fragments with 1H chemical shiftsobtained by assignment procedures starting from the polypeptide backbone.Since guanidino protons exchange quite rapidly with the bulk water, the 2DHE(NE)HGHH pulse scheme has been optimized to avoid saturation and dephasingof the water magnetization during the course of the experiment. As anillustration, arginine side chain assignments are presented for two uniformly15N-labeled proteins of 7 and 23 kDa molecular weight. 相似文献
35.
Keith L. Constantine Mark S. Friedrichs David Detlefsen Maki Nishio Mitsuaki Tsunakawa Tamotsu Furumai Hiroaki Ohkuma Toshikazu Oki Susan Hill Robert E. Bruccoleri Pin-Fang Lin Luciano Mueller 《Journal of biomolecular NMR》1995,5(3):271-286
Summary The 21-amino acid peptides siamycin II (BMY-29303) and siamycin I (BMY-29304), derived from Streptomyces strains AA3891 and AA6532, respectively, have been found to inhibit HIV-1 fusion and viral replication in cell culture. The primary sequence of siamycin II is CLGIGSCNDFAGCGYAIVCFW. Siamycin I differs by only one amino acid; it has a valine residue at position 4. In both peptides, disulfide bonds link Cys1 with Cys13 and Cys7 with Cys19, and the side chain of Asp9 forms an amide bond with the N-terminus. Siamycin II, when dissolved in a 50:50 mixture of DMSO and H2O, yields NOESY spectra with exceptional numbers of cross peaks for a peptide of this size. We have used 335 NOE distance constraints and 13 dihedral angle constraints to generate an ensemble of 30 siamycin II structures; these have average backbone atom and all heavy atom rmsd values to the mean coordinates of 0.24 and 0.52 Å, respectively. The peptide displays an unusual wedge-shaped structure, with one face being predominantly hydrophobic and the other being predominantly hydrophilic. Chemical shift and NOE data show that the siamycin I structure is essentially identical to siamycin II. These peptides may act by preventing oligomerization of the HIV transmembrane glycoprotein gp41, or by interfering with interactions between gp41 and the envelope glycoprotein gp120, the cell membrane or membrane-bound proteins [Frèchet, D. et al. (1994) Biochemistry, 33, 42–50]. The amphipathic nature of siamycin II and siamycin I suggests that a polar (or apolar) site on the target protein may be masked by the apolar (or polar) face of the peptide upon peptide/protein complexation.Abbreviations ABNR
adopted basis Newton Raphson
- AIDS
acquired immunodeficiency syndrome
- CW
continuous wave
- DMSO
dimethylsulfoxide
- DQF-COSY
two-dimensional double-quantum-filtered correlation spectroscopy
- HIV
human immunodeficiency virus
- HSQC
heteronuclear single-quantum coherence
- NOE
nuclear Overhauser enhancement
- NOESY
two-dimensional nuclear Overhauser enhancement spectroscopy
- ppm
parts per million
- P.E.-COSY
two-dimensional primitive exclusive correlation spectroscopy
- REDAC
redundant dihedral angle constraint
- rf
radio frequency
- rmsd
root-mean-square difference
- SIV
simian immunodeficiency virus
- sw
spectral width
- m
mixing time
- TOCSY
two-dimensional total correlation spectroscopy
- TSP
trimethylsilyl-2,2,3,3-2H4-propionate
- 2D
two-dimensional 相似文献
36.
Tada Mikiro; Shiroishi Masahide; Hasegawa Kiyozo; Suzuki Tetsuya; Iwai Kazuo 《Plant & cell physiology》1982,23(4):607-614
The effect of light on the production of ergosterol and phytoeneand on the composition of carotenoids in Rhodotorula minutawas studied to determine which part of the pathway of carotenoidsynthesis regulated by light. The ergosterol content in the cells was in the range of 3.43.6mg/g dry cells regardless of the presence or absence of illuminationand the light intensity. The phytoene production in the cellswas markedly stimulated by light and was dependent on the lightintensity according to the amount of carotenoid pigments produced.In addition, the ratio of phytoene to carotenoid was in therange of 0.360.44, regardless of the presence or absenceof illumination and the light intensity. The fact that the ratio of carotenoid fractionated on the basisof the functional group involved in each carotenoid to the totalamount of carotenoid was almost constant regardless of the lightintensity suggested that the composition of the carotenoidssynthesized in the cells is not affected by light. It was deduced from these results that light induced the productionof enzyme(s) required for phytoene biosynthesis in Rhodotorulaminuta. (Received November 7, 1981; Accepted March 19, 1982) 相似文献
37.
Masakiyo Iwai Hiroshi Kanno Masashi Hashino Jinichi Suzuki Takumi Yanaihara Tetsuya Nakayama 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1981,225(2)
A simple, rapid and highly specific method by selected ion monitoring (SIM), using 9α,11α-[2H2]estrone, [2,4-2H2]estradiol-17β and 2,4-[2H2]estriol as internal standards, was developed for the determination of serum estrogens during pregnancy. Serum samples were submitted to a simple extraction procedure and were analysed after formation of the trifluoroacetic anhydride derivative. The inter-assay coefficients of variation for estrone, estradiol-17β and estriol were 3.73%, 3.42% and 3.49%, respectively. The results obtained by SIM were compared with analysis performed using radioimmunoassay. 相似文献
38.
39.
To understand the incompatibility between two related plasmids, both of which replicate in an autonomous state under a common control mechanism, we have developed a model that assumes a random choice mechanism for replication of plasmid copies and their random assortment into daughter cells upon cell division. Segregation kinetics by this model is analyzed mathematically and the number of generations required for segregation is calculated as a function of plasmid copy number per cell. The results obtained offer enough quantitative data to make our model reasonably realistic. 相似文献
40.
Phorbol esters (TPA) and concanavalin A (ConA) are known to induce granulocyte-macrophage colony-stimulating factor (GM-CSF) production in murine thymoma EL-4 cells by mRNA stabilization. The role of the 3'-untranslated region (3'-UTR) in GM-CSF mRNA stabilization induced by TPA and ConA in EL-4 cells was examined by transfection studies using chloramphenicol acetyltransferase (CAT) constructions. The GM-CSF 3'-UTR contains a 63-nucleotide region at its 3' end with repeating ATTTA motifs which is responsible for mRNA degradation in a variety of cell types (Shaw, G., and Kamen, R. (1986) Cell 46, 659-666). We produced constructs containing most of the GM-CSF 3'-UTR (303 nucleotides, pRSV-CATgm) or the 3'-terminal AT-rich region (116 nucleotides, pRSV-CATau) and measured CAT enzyme activity and CAT mRNA after transient transfection into EL-4 and NIH 3T3 cells. Low levels of CAT activity were seen in both cells with either plasmid compared with levels of CAT activity obtained with pRSV-CAT. TPA treatment caused an approximately 10-fold increase in CAT activity and mRNA in EL-4 cells transfected with pRSV-CATgm. No increases were seen in EL-4 cells transfected with pRSV-CATau or pRSV-CAT. No response to TPA was detected in transfected NIH 3T3 cells, indicating that the response to TPA is relatively cell-specific. There was no increase in CAT activity after ConA treatment in EL-4 or NIH 3T3 cells transfected with any of the constructs suggesting that the GM-CSF 3'-UTR lacks elements that can respond alone to ConA. Nuclear run-on and actinomycin D chase experiments in EL-4 cells showed that TPA induces CAT activity via mRNA stabilization. By linker-substitution mutagenesis we show that TPA inducibility depends on a 60-nucleotide region of the 3'-UTR whose 5' end is located 160 nucleotides upstream of the 5' end of the AU-rich region. 相似文献