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121.
Kimura Y Koitabashi S Kakizuka A Fujita T 《The Journal of biological chemistry》2002,277(40):37536-37541
Polyglutamine disease is now recognized as one of the conformational, amyloid-related diseases. In this disease, polyglutamine expansion in proteins has toxic effects on cells and also results in the formation of aggregates. Polyglutamine aggregate formation is accompanied by conversion of the polyglutamine from a soluble to an insoluble form. In yeast, the efficiency of the aggregate formation is determined by the balance of various parameters, including the length of the polyglutamine tract, the function of Hsp104, and the level of polyglutamine expression. In this study, we found that the co-expression of a long polyglutamine tract, which formed aggregates independently of the function of Hsp104, enhanced the formation of aggregates of a short polyglutamine tract in wild-type cells as well as in Deltahsp104 mutant cells. Thus, the expression of a long polyglutamine tract would be an additional parameter determining the efficiency of aggregate formation of a short polyglutamine tract. The co-localization of aggregates of long and short polyglutamine tracts suggests the possibility that the enhancement occurs due to the seeding of aggregates of the long polyglutamine tracts. 相似文献
122.
Fujimori A Hashimoto H Araki R Saito T Sato S Kasama Y Tsutsumi Y Mori M Fukumura R Ohhata T Tatsumi K Abe M 《Radiation research》2002,157(3):298-305
The catalytic subunit of DNA-dependent protein kinase plays critical roles in nonhomologous end joining in repair of DNA double-strand breaks and V(D)J recombination. In addition to the SCID phenotype, it has been suggested that the molecule contributes to the polymorphic variations in radiosensitivity and susceptibility to cancer in mouse strains. Here we show the nucleotide sequence of approximately 193-kbp and 84-kbp genomic regions encoding the entire Prkdc gene (also known as DNA-PKcs) in the mouse and chicken, respectively. A large retroposon was found in intron 51 in the mouse but not in the human or chicken. Comparative analyses of the genome strongly suggested that the region contains only two genes for Prkdc and Mcm4; however, several conserved sequences and cis elements were also predicted. 相似文献
123.
Itoh K Kanda R Sumita Y Kim H Kamagata Y Suyama K Yamamoto H Hausinger RP Tiedje JM 《Applied and environmental microbiology》2002,68(7):3449-3454
The 2,4-dichlorophenoxyacetate (2,4-D)/alpha-ketoglutarate dioxygenase gene (tfdA) homolog designated tfdAalpha was cloned and characterized from 2,4-D-degrading bacterial strain RD5-C2. This Japanese upland soil isolate belongs to the Bradyrhizobium-Agromonas-Nitrobacter-Afipia cluster in the alpha subdivision of the class Proteobacteria on the basis of its 16S ribosomal DNA sequence. Sequence analysis showed 56 to 60% identity of tfdAalpha to representative tfdA genes. A MalE-TfdAalpha fusion protein expressed in Escherichia coli exhibited about 10 times greater activity for phenoxyacetate than 2,4-D in an alpha-ketoglutarate- and Fe(II)-dependent reaction. The deduced amino acid sequence of TfdAalpha revealed a conserved His-X-Asp-X(146)-His-X(14)-Arg motif characteristic of the active site of group II alpha-ketoglutarate-dependent dioxygenases. The tfdAalpha genes were also detected in 2,4-D-degrading alpha-Proteobacteria previously isolated from pristine environments in Hawaii and in Saskatchewan, Canada (Y. Kamagata, R. R. Fulthorpe, K. Tamura, H. Takami, L. J. Forney, and J. M. Tiedje, Appl. Environ. Microbiol. 63:2266-2272, 1997). These findings indicate that the tfdA genes in beta- and gamma-Proteobacteria and the tfdAalpha genes in alpha-Proteobacteria arose by divergent evolution from a common ancestor. 相似文献
124.
Morohoshi T Maruo T Shirai Y Kato J Ikeda T Takiguchi N Ohtake H Kuroda A 《Applied and environmental microbiology》2002,68(8):4107-4110
The biological process for phosphate (P(i)) removal is based on the use of bacteria capable of accumulating inorganic polyphosphate (polyP). We obtained Escherichia coli mutants which accumulate a large amount of polyP. The polyP accumulation in these mutants was ascribed to a mutation of the phoU gene that encodes a negative regulator of the P(i) regulon. Insertional inactivation of the phoU gene also elevated the intracellular level of polyP in Synechocystis sp. strain PCC6803. The mutant could remove fourfold more P(i) from the medium than the wild-type strain removed. 相似文献
125.
126.
Coevolution of the S-locus genes SRK,SLG and SP11/SCR in Brassica oleracea and B. rapa 总被引:1,自引:0,他引:1
Sato K Nishio T Kimura R Kusaba M Suzuki T Hatakeyama K Ockendon DJ Satta Y 《Genetics》2002,162(2):931-940
Brassica self-incompatibility (SI) is controlled by SLG and SRK expressed in the stigma and by SP11/SCR expressed in the anther. We determined the sequences of the S domains of 36 SRK alleles, 13 SLG alleles, and 14 SP11 alleles from Brassica oleracea and B. rapa. We found three S haplotypes lacking SLG genes in B. rapa, confirming that SLG is not essential for the SI recognition system. Together with reported sequences, the nucleotide diversities per synonymous and nonsynonymous site (pi(S) and pi(N)) at the SRK, SLG, and SP11 loci within B. oleracea were computed. The ratios of pi(N):pi(S) for SP11 and the hypervariable region of SRK were significantly >1, suggesting operation of diversifying selection to maintain the diversity of these regions. In the phylogenetic trees of 12 SP11 sequences and their linked SRK alleles, the tree topology was not significantly different between SP11 and SRK, suggesting a tight linkage of male and female SI determinants during the evolutionary course of these haplotypes. Genetic exchanges between SLG and SRK seem to be frequent; three such recent exchanges were detected. The evolution of S haplotypes and the effect of gene conversion on self-incompatibility are discussed. 相似文献
127.
Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal position in a filament. In the present study, we have analyzed the mechanism for position sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in position sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd(3+) or decrease in extracellular Ca(2+) resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in position sensing by terminal cells. 相似文献
128.
Differential expression of tissue factor and tissue factor pathway inhibitor in metastatic melanoma lesions 总被引:3,自引:0,他引:3
Kageshita T Funasaka Y Ichihashi M Ishihara T Tokuo H Ono T 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2002,15(3):212-216
Tissue factor (TF) is involved in tumor progression and metastatic potency in some malignant tumors and its function is regulated by tissue factor pathway inhibitor (TFPI) therefore the interaction of both molecules is crucial for their functional role. We evaluated the clinical relevance of TF and TFPI expression in benign and malignant melanocytic lesions. Expression of both was examined by immunoperoxidase staining using serial tissue sections in 16 nevi, 34 primary and 15 metastatic melanoma lesions. TF and TFPI were ubiquitously expressed in benign and malignant melanocytic lesions. This finding was confirmed by Western blot analysis using cultured human melanocytes, nevi cells (NCN) and melanoma cell lines. Although TF expression was not associated with malignant transformation and disease progression, TFPI expression in primary and metastatic melanoma lesions was significantly lower and weaker than that in nevi lesions in terms of intensity and percentage of stained cells. In addition, TFPI expression in metastatic lesions was significantly lower and weaker than that of TF. These results suggest that the relative expression of TF to TFPI may play a crucial role in the malignant transformation and metastatic potency in melanocytic cells. 相似文献
129.
Isolation of three main sericin components from the cocoon of the silkworm,Bombyx mori 总被引:1,自引:0,他引:1
To characterize the sericin components of the cocoon of silkworm Bombyx mori, fresh cocoon shells were dissolved in saturated aqueous lithium thiocyanate containing 2-mercaptoethanol, and fractionated by ethanol precipitation. Cocoon sericin was found to mainly consist of three polypeptides having molecular masses of the 400, 250, and 150 kDa estimated by SDS-PAGE, which corresponds to the sericin present in the middle, anterior, and posterior part of the middle silk gland. The amino acid compositions of the 400 and 150 kDa components were similar to each other, but that of the 250 kDa component was different. This suggests differences in the coding gene and properties of the 250 kDa sericin from the other two. 相似文献
130.
Ichiro Tayasu Toshio Nakamura Hirotaka Oda Fujio Hyodo Yoko Takematsu Takuya Abe 《Ecological Research》2002,17(2):195-206
Stable (13C and 15N) and radio- (14C, 137Cs and 210Pb) isotopes were determined for termites that
have been sampled from a dry evergreen forest in Thailand. A wood-feeding termite, Microcerotermes crassus, was separated from soil-feeders: Termes propinquus, Termes comis and Dicuspiditermes makhamensis by 13C and 15N values. The Termes group in Thailand had less diverse values in 13C and 15N than those in Australia, where the feeding habits of the Termes group are more diverse. Other soil-feeding termites produced similar 13C values, but a larger range in 15N values. 14C-percent modern carbon (pMC) values suggest that the soil-feeding termites used younger carbon than the wood-feeding termites, and this was consistent with the termites from Cameroon, central Africa. Values of 13C and 14C-pMC indicate that surface soil was used by a soil-feeding termite, D. makhamensis, in making the nest mounds, and deeper soil (10–30 cm) by a fungus-growing termite, Macrotermes carbonarius. 210Pb and 137Cs were scarcely incorporated into the termites, although 214Pb was recovered from the workers. The results suggest that stable- and radioisotopes are useful in the study of detritivorous animals, organic matter decomposition and ecosystem engineering.Takuya Abe - deceased. 相似文献