Idengaku zasshi最新文献

Three genomic DNA fragments containing the tyrosinase-encoding gene (TYR) of the Japanese pond frog, Rana nigromaculata, were cloned. The first, clone I, was isolated from a genomic library of sperm DNA using the mouse TYR cDNA as the probe and contained a DNA segment similar to exon 4 of the mouse TYR gene. Subsequently, the TYR cDNA was isolated by screening a frog embryo cDNA library using clone I as the probe. Two clones that contain genomic DNA of the TYR gene were isolated also from a blood cell DNA library using the frog TYR cDNA as the probe. Comparison of the nucleotide (nt) sequences of the genomic clone II DNA and the cDNA revealed that clone II contained a 3,140-bp DNA fragment consisting of the 5'-flanking region, the first exon, and a part of the first intron. The region upstream of the coding region contained the characteristic sequences for regulatory elements, including TATA- and CAAT-motifs, and also a pigment cell-specific promoter element, which is shared by the promoter regions of the vertebrate TYR genes. A 764-bp segment containing an upstream 748-bp non-coding region and 16-bp coding region was functional for expression of the promoter-less cat gene on a plasmid in the transiently transformed albino frog melanophore. The genomic clone III contained the 3'-untranslated region of the mRNA and its 3'-flanking region. Thus, the cDNA plus genomic DNA fragments isolated here cover the entire TYR gene and its flanking regions.

Morphometric differentiation among six strains of musk shrews (Suncus murinus) originating in Bangladesh (BAN), Sri Lanka (SRI), and four Japanese areas, Nagasaki (NAG), Okinawa Island (OKI), Tokunoshima Island (TKU), and Taramajima Island (TR), was examined by use of skull and external measurements. These data were compared with mitochondrial DNA (mtDNA) differentiation previously reported. Significant sexual dimorphism was observed in all morphometric characters of the six strains, except for two characters in the TR strain. The six strains were clearly grouped by principal component analysis into three body-size types: large BAN shrews, intermediate SRI shrews, and small Japanese shrews. By canonical discriminant analysis, the NAG strain was further distinct from the other three Japanese strains despite their apparent similarities in external morphology, and was characterized by having the most unusual shape in the six strains. No individuals were misclassified as to their geographic origin for both sexes of the six strains. The morphometric differentiation pattern based on only the first canonical variate, extracting an overall size factor, was concordant with the mtDNA differentiation pattern (rss = 0.944, P < 0.001 in males and rss = 0.930, P < 0.001 in females). In contrast, the morphometric differentiation pattern estimated from the second to the fifth canonical variates, representing shape factors, was apparently discordant with the mtDNA differentiation pattern (rss = 0.467, P > 0.05 in both sexes). It was previously reported that a partial premating reproductive isolation mechanism is caused by the difference in body size between mating pairs. Thus, body size may be a factor useful for understanding the mechanisms of population differentiation in this species.

To obtain insight into the nature and mechanisms of spontaneous mutations, Escherichia coli K12 strain TM31 was constructed to determine, by DNA sequencing, the mutational spectrum of the tonB gene on the chromosome. We inserted the chloramphenicol resistant gene 1.6 kb upstream of the tonB gene, thus making it possible to retrieve the mutated tonB gene from the chromosome by shotgun cloning using a drug-resistant marker. The spontaneous mutation frequency in the tonB gene, which was judged by its colicin B-resistant phenotype, is 3-10 x 10(-7). Spontaneous mutations were dominated by large insertions that are identified by DNA sequencing to be IS elements; IS1 dominated, but IS2, IS5, and IS10 were also obtained. In uvrA- strain, transposition of both IS10-R and IS10-L are equally increased, suggesting the interaction of the UvrA protein and IS10 transposition. The base substitutions are the second largest group of mutations, among which G:C-->A:T transition is predominant. Deletions also contribute significantly in wild type with regard to DNA repair and uvrA- strains, but not recA- strain, suggesting that the RecA protein is involved to some extent in deletion formation. Endpoints of these deletions do not always correlate with the presence of repeated sequences, indicating the absence of homologous recombination for deletion formation.

Three species of Shorea (S. leprosula, S. acuminata and S. cursitii) were collected from a natural forest reserve of Malaysia and analyzed for genetic variation using the technique of random amplification of polymorphic DNA (RAPD) by the polymerase chain reaction (PCR). The average number of nucleotide substitutions was estimated. The nucleotide diversities within species were very similar and larger than those found in Drosophila melanogaster. The nucleotide divergences between these species are about 1.5 times the nucleotide diversities within the species, indicating that these species diverged from a common ancestor relatively recently.

Drosophila RBP-J kappa is a novel sequence-specific DNA binding protein encompassing the integrase motif which is highly conserved in various organisms. Its gene has been shown to be identical to Suppressor of Hairless which regulates adult peripheral nervous system (PNS) development. To elucidate the precise function of the RBP-J kappa protein in adult PNS development, we analyzed transgenic files that misexpress the RBP-J kappa protein. Such studies have shown that RBP-J kappa regulates PNS cell fate in at least two steps: commitment to sensory mother cell by lateral inhibition and terminal differentiation into the socket and shaft cells. Taken together with analysis of phenotypes of Suppressor of Hairless mutants, RBP-J kappa shows the synergistic activity with neurogenic genes.

We have isolated a cDNA homologous to the yeast DMC1 and RAD51 genes from Drosophila melanogaster. The DMC1 and RAD51 genes of Saccharomyces cerevisiae are known to play crucial roles during meiosis and during both meiosis and mitosis, respectively, and their gene products are homologous to each other and to the RecA protein of Escherichia coli. The cDNA cloned here contains an open reading frame that encodes 336 amino acids. Sequence analysis of the corresponding genomic DNA fragment showed one short intron existing in the coding region as in the DMC1 gene, but not in the RAD51 gene. By in situ hybridization to the salivary gland chromosomes, the recA-like gene was cytologically mapped to 99D of the third chromosome.

The structural locus for alpha-amylase (AMY) in Drosophila melanogaster is duplicated and divergently transcribed. These two genes are designated as Amy-p and Amy-d, respectively. We searched for the cis-acting regulatory elements for full expression of the duplicated Amy-p and Amy-d loci, by injecting plasmid constructs containing sequences from the Amy locus into preblastoderm embryos of an AMY-null strain and measuring exogenous AMY activity produced in transformed host larvae (i.e., the transient expression assay). Relative activities of endogenous amylase isozymes, AMY-1 and AMY-3, in extracts of AMY1,3 larvae of a Canton-S are almost the same. However, three independently isolated Amy-p1 constructs with only the 5' upstream regions of Amy-p1 expressed a very low AMY-1 activity. Two other Amy-p1 constructs with the 5' upstream region of Amy-d3 in addition to that of Amy-p1 produced a high activity. Thus, the 5' upstream region of Amy-d3 is necessary for full expression of Amy-p1. In order to locate cis-regulatory elements within the 5' region of Amy-d3, a series of hybrid constructs including this region were tested to locate them. Our results clearly show that the cis-acting regulatory sequences required for full expression of Amy-p1 are located between the base pairs at -304 and -372 upstream of Amy-d3 gene. In other words, only a short region located upstream of Amy-d3 was found to be necessary and sufficient for the full expression of Amy-p1 in addition to its promoter. This region seems also necessary for the expression of Amy-d3.

The genetic polymorphism of placental glucose dehydrogenase (GDH) was investigated in 300 Korean placentae using horizontal starch gel electrophoresis. The allele frequencies for GDH1, GDH2 and GDH3 were 0.537, 0.440 and 0.005, respectively, which were similar to those in Japanese. We also observed an anodal allele which was similar to the GDH4 originally reported in Chinese populations at a low frequency of 0.015. An additional new cathodal allele (named GDH6) was observed in the present study with a very low frequency of 0.003.

The cps3 gene of the fission yeast, Schizosaccharomyces pombe, was previously identified as a mutation conferring supersensitivity to the spindle poison, isopropyl N-3-chlorophenyl carbamate (CIPC). A 3.2 kb DNA fragment that complements the mutant phenotype was cloned from a S. pombe genomic library. The base sequence analysis showed that the fragment contains a maximum 1086 nucleotide open reading frame and that the putative product consists of 362 amino acids, having a molecular weight of 39.3 KDa. No significant homology of the potential product with known proteins could be found by database searches. A disruptant of the gene, produced by insertion of a ura4+ fragment was able to germinate, but not to undergo cell division, suggesting that the gene to be essential for the cell cycle progression. The disruption experiment suggests that the gene is an extragenic suppressor of cps3 mutation.

Using fluorescent in situ hybridization (FISH) method, gene encoding the catalytic subunit of protein phosphatase type 1 beta (PPP1CB) in human and its corresponding gene in rat (PP1 delta) and mouse (dis2m2) were mapped to human 2p23, rat 6q21-q23, and mouse 12D, respectively. These results indicate that PPP1CB is a member of conserved syntenic group. It is shown that the genes encoding catalytic subunit of protein phosphatase type 1 family (PP1 alpha, PP1 beta, and PP1 gamma in human and those corresponding genes in rat and mouse), in spite of their high identity, are located to different chromosomes in these three species.