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E Tsuchiya

Publications and source records attributed to E Tsuchiya.

99 records · Page 6Linked to original sources
PubMed1984

Mating pheromone-induced alteration of cell surface proteins in the heterobasidiomycetous yeast Tremella mesenterica.

Mating pheromone-induced alteration of the cell surface proteins of haploid cells, presumed to play crucial roles in the specific cell-cell interactions during sexual conjugation of Tremella mesenterica , was investigated. Exposed surface proteins were revealed by lactoperoxidase-catalyzed iodination in combination with polyacrylamide gel electrophoresis and autoradiography. From comparison of the molecular species of 125I-labeled surface proteins of the vegetative and the gamete (mating pheromone-treated) cells of the two compatible mating types (ab and AB), it was suggested that a striking change in cell surface structure occurs during the differentiation; although labeled protein species of the vegetative cells of the two mating types were indistinguishable, several new species, both mating type specific and nonspecific, appeared in the gamete cells. Turnover of the labeled proteins of the vegetative cells was negligible, whereas that of the gamete cells was rapid with release of low-molecular-weight labeled proteins in the medium. A role for the labeled surface proteins of the gamete cells in the cell-cell interactions during sexual conjugation was suggested by the following: the surface changes were induced by mating pheromone; the labeled proteins were preferentially localized on the surface of the mating tube; the labeled species appeared sequentially during the differentiation; and mating type-specific species were present in both mating types.

Animals↗
PubMed1984

Lack of promotion effect of phenobarbital on pulmonary tumorigenesis in ddy mice initiated by transplacental exposure to 1-ethyl-1-nitrosourea.

The promoting effect of phenobarbital (PB) on lung tumorigenesis in mice was examined. Pregnant ddy female mice were injected ip with a single dose of 50 mg/kg 1-ethyl-1-nitrosourea at the 16th day of gestation. Offspring, 160 in total, were divided into two groups: one group of animals was fed a diet containing 0.05% PB continuously and the other was kept on the basal diet. All the animals were killed at 6 months of age and the number, size and histology of pulmonary tumors were examined. There were over 10 pulmonary tumors per animal on average, measuring from 0.5 to 10.2 mm in size, and the histology varied from grade I to III in atypism. A comparative study revealed no difference between PB-treated and control mice in any aspect of the tumorigenesis. It was concluded that PB does not have promoting effect on pulmonary tumorigenesis in this system.

Animals↗
PubMed1982

Role of metabolism of the mating pheromone in sexual differentiation of the heterobasidiomycete Rhodosporidium toruloides.

A trypsin-type endopeptidase (Kamiya et al., Biochem. Biophys. Res. Commun. 94:855-860, 1980) responsible for the metabolism of rhodotorucine A, the farnesyl undecapeptide mating pheromone secreted by mating type A cells of Rhodosporidium toruloides, was biologically characterized. Metabolic activity was found to be present exclusively on the cell surface of the pheromone target cell. The activity was highly specific to the pheromone, and a biologically inactive analog which has the complete amino acid sequence of rhodotorucine A but lacks the farnesyl residue was not metabolized by intact cells. Pheromone metabolism was inhibited by trypsin substrates such as tosyl-L-arginine methyl ester. The presence of tosyl-L-arginine methyl ester strongly inhibited the sexual differentiation induced by the pheromone at a concentration which did not affect the vegetative growth of R. toruloides. Pheromone-induced sexual differentiation was also strongly inhibited by a metabolizable analog, rhodotorucine A S-oxide, but not by a non-metabolizable one. In mutants defective in early processes of mating, the decrease in the pheromone metabolic activity correlated well with the extent of loss of sensitivity to the pheromone. Both the pheromone metabolism and the capacity for sexual differentiation of a sterile mutant were restored concomitantly with reversion from the sterile to the fertile phenotype. These results suggested that metabolism of the mating pheromone plays an essential role in the process of sexual differentiation in R. toruloides.

Basidiomycota↗
PubMedDate not supplied

Reduced HIC-1 gene expression in non-small cell lung cancer and its clinical significance.

BACKGROUND: HIC-1 (hypermethylated in cancer-1) is a candidate tumor suppressor gene, identified in a region of frequent loss of heterozygosity on chromosome 17p13.3, which is telomeric from TP53 and often deleted in surgically resected lung cancers. To determine the significance of HIC-1 in lung cancer, we assessed its expression status and prognostic association in 47 adenocarcinomas and squamous cell carcinomas. MATERIALS AND METHODS: RNA was extracted from tumors and corresponding normal tissues of surgically resected lungs, and the amount of HIC-1 mRNA was determined by means of semi-quantitative reverse transcriptase-polymerase chain reaction. RESULTS: HIC-1 expression in tumors was less than that in normal lung tissues in 40 of 47 patients (85%), indicating frequent partial silencing. Median tumor/normal lung tissue (T/L) ratios for HIC-1 expression were 0.51 and 0.75 for adenocarcinomas and squamous cell carcinomas, respectively. No significant difference of median T/L ratio was observed between the two histological types, or among clinical stages of the patients. However, the reduced expression of HIC-1 gene in the tumor had a direct link with the clinical outcome: lower T/L ratios (< 0.5) were significantly associated with short survival (P = 0.034), an association also observed in cases restricted to stage I (P = 0.047). CONCLUSIONS: The results suggest that low HIC-1 expression is involved in malignant progression of non-small cell lung cancer.

Adenocarcinoma↗