Idengaku zasshi最新文献

Four kinds of circular plasmid-like DNA, designated B1, B2, B3 and B4, have been found in the mitochondria of Oryza sativa L. with an AA genome. Three novel B1-homologous mitochondrial plasmid-like DNAs, designated, M1, M2 and M3, were isolated in the present study from strains with CC and CCDD genomes in the genus Oryza. We cloned and sequenced these DNAs and found that the sequences of these molecules have wide regions of homology. B1, M2 and M3 each lack about 300 bp of a region that is present in M1 and small repeats were found at the sites of deleted sequences. Therefore, we propose the hypothesis that the B1 family differentiated from a common ancient molecule that was similar to M1 via, probably, slipped mispairing during DNA replication at several stages in the evolution in the genus Oryza.

Protein tyrosine phosphatases (PTPases) negatively regulate the effect(s) of protein tyrosine kinases and are implicated in the regulation of a variety of biological events including cell activation, differentiation, and neoplastic transformation. To gain insight into the role(s) of the PTPases, we mapped the gene encoding for the widely expressed receptor-like protein tyrosine phosphatase PTP alpha/LRP (locus symbol Ptpra) to rat chromosome 3q36 and mouse chromosome 2G by fluorescence in situ hybridization method. These results indicate that there is a conserved syntenic group between human 20p13, rat 3q36, and mouse 2G.

To estimate approximate times of divergence of animal phyla lacking fossil data, it is important to find a molecule that evolves with an approximately constant rate over a wide evolutionary distance covering the whole animal phyla. For this purpose, the evolutionary rate constancy has been examined for 20 proteins. It was found that four proteins, particularly the aldolase C, involved in the glycolitic pathway, had evolved with rates that are approximately constant not only among different classes of vertebrates, but also between vertebrates and arthropods. The evolutionary rate (= 0.26 x 10(-9)/site/year) of the aldolase C is likely to have remained essentially unchanged even between animals and plants.

Four kinds of circular plasmid-like DNA, designated B1, B2, B3 and B4, have been found in the mitochondria of rice (Oryza sativa L.). We analyzed the distribution of families of plasmid-like DNAs homologous to those of O. sativa in 40 strains of the genus Oryza with AA, BB, BBCC, CC, CCDD and EE genomes. Plasmid-like DNAs were observed only strains having AA, CC and CCDD genomes. The distribution patterns of strains with AA genome were highly polymorphic. We amplified the plasmid-like DNAs from strains with the AA genome by PCR and examined restriction fragments length polymorphisms (RFLPs). RFLPs were detected among families of plasmid-like DNA amplified from different strains. This result indicated that some mutations, such as base substitutions and the insertion or deletion of a small fragment of DNA, had occurred and had accumulated during the differentiation of strains with an AA genome.

Erythropoietin stimulates proliferation and differentiation of erythroid progenitor cells by binding to a specific membrane receptor, erythropoietin receptor. By using the genomic clone derived from a rat cosmid library, the rat erythropoietin receptor gene was assigned to chromosome 8q24 by fluorescence in situ hybridization.

In a mouse specific-locus test in stem-cell spermatogonia of mice after treatment with N-ethyl-N-nitrosourea (ENU), a mutation at the hemoglobin alpha-chain locus was obtained. In an original mutant, the mutation was detected as a change in band density using cellulose acetate electrophoresis, e.g. the slow moving band was much higher than that of normal F1 mice. Yet, migration of the mouse bands was similar. In isoelectric focusing, the migration of a band toward cathode was observed, indicating that the variant hemoglobin is caused by mutation at an alpha-globin chain. This mutation was found to be heritable and viable in homozygous condition from a genetic test on the mutant, suggesting that this mutation would be due to a base-pair change. According to the usual nomenclature of mutation at the hemoglobin locus, the allele symbol of this mutation was tentatively designated as Hbacc3.

Suppressor of Hairless[Su(H)], the Drosophila homologue of RBP-J kappa is a novel type of sequence-specific DNA binding protein without known motifs, and highly conserved in various organisms. Su(H) regulates peripheral nervous system (PNS) development. Recently Su(H) was suggested to participate in the Notch-mediated signal transduction pathway. We show here that the Su(H) protein binds to TGTGGGAA sequence located 616 base-pairs upstream of the transcription initiation site of the Enhancer of split [E(spl)]m8 gene which is mapped to the terminus of the genetic cascade of the neurogenic genes. Su(H) transactivates the E(spl)m8 promoter not only in cultured Drosophila cells but also in vivo. The present study bridges the biochemical gap between Notch and E(spl) in the neurogenic gene cascade including Delta, Notch, deltex, Su(H), Hairless and E(spl).

Distribution of a family of tandemly repetitive sequences in Hemitaxonus japonicus (pYS family) was investigated among eight sawfly species and host races in the genus Hemitaxonus. High copy numbers of the repetitive sequences were detected in the two host plant races of H. japonicus, race Polystichum polyblepharum (race PP) and race P. tripteron (race PT), and H. sasayamensis, whereas a low copy number in H. minomensis. Comparison of the nucleotide sequences of the basic repeat units demonstrated a high degree of homology among the four tested species with high AT-rich sequences. Minor repeat units shorter than the consensus basic repeat unit of pYS family were found only in races PP and PT of H. japonicus. Analyses of their nucleotide sequences showed the occurrence of the host race specific sub-repeat units.

Experiments were designed to estimate the variation of alpha-amylase activity in Drosophila subobscura individuals homozygous for AmyS and AmyF alleles at the Amy locus. The measurements of enzyme activities in six groups of male progenies determined in each individual have shown that degree of variation differs between S and F strains. Variability of amylase activity among male progenies of S strain was substantially greater, which also had significantly higher specific amylase activity than in F strain. The analysis of amylase activity variance showed that this variance among the males is 40 times, and among the females 2.7 times smaller in F than in S strain.