Genes & Genetic Systems
Online ISSN : 1880-5779
Print ISSN : 1341-7568
ISSN-L : 1341-7568
87 巻 , 2 号
選択された号の論文の8件中1~8を表示しています
Review
  • Yuki Ogiyama, Kojiro Ishii
    原稿種別: Review
    2012 年 87 巻 2 号 p. 63-73
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    The centromere functions as a unique chromosomal attachment site for microtubules. Appropriate microtubule attachment is fundamental for organized chromosome behavior during mitosis and meiosis. Hence, centromeres must function both smoothly and stably. However, centromeric DNA sequences are poorly conserved between species despite common functions and similar centromeric protein composition, which leads us to the question: how are centromeres established and maintained? In this review, we summarize the recent progress in deciphering the mechanisms of centromere function. Specifically, we focus our attention on mechanisms closely-related to centromeric DNA and chromatin. By gathering such information, we hope to reveal a new dimension to the true nature of centromeres.
Full papers
  • Tetsuya Mori, Tatsuro Nakamura, Naoto Okazaki, Asako Furukohri, Hisaji ...
    原稿種別: Full paper
    2012 年 87 巻 2 号 p. 75-87
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    The SOS response is readily triggered by replication fork stalling caused by DNA damage or a dysfunctional replicative apparatus in Escherichia coli cells. E. coli dinB encodes DinB DNA polymerase and its expression is upregulated during the SOS response. DinB catalyzes translesion DNA synthesis in place of a replicative DNA polymerase III that is stalled at a DNA lesion. We showed previously that DNA replication was suppressed without exogenous DNA damage in cells overproducing DinB. In this report, we confirm that this was due to a dose-dependent inhibition of ongoing replication forks by DinB. Interestingly, the DinB-overproducing cells did not significantly induce the SOS response even though DNA replication was perturbed. RecA protein is activated by forming a nucleoprotein filament with single-stranded DNA, which leads to the onset of the SOS response. In the DinB-overproducing cells, RecA was not activated to induce the SOS response. However, the SOS response was observed after heat-inducible activation in strain recA441 (encoding a temperature-sensitive RecA) and after replication blockage in strain dnaE486 (encoding a temperature-sensitive catalytic subunit of the replicative DNA polymerase III) at a non-permissive temperature when DinB was overproduced in these cells. Furthermore, since catalytically inactive DinB could avoid the SOS response to a DinB-promoted fork block, it is unlikely that overproduced DinB takes control of primer extension and thus limits single-stranded DNA. These observations suggest that DinB possesses a feature that suppresses DNA replication but does not abolish the cell’s capacity to induce the SOS response. We conclude that DinB impedes replication fork progression in a way that does not activate RecA, in contrast to obstructive DNA lesions and dysfunctional replication machinery.
  • Qi Shen, Jinming Zhao, Caifu Du, Yang Xiang, Jinxuan Cao, Xinrong Qin
    原稿種別: Full paper
    2012 年 87 巻 2 号 p. 89-98
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    In plants, powdery-mildew-resistance locus o (Mlo) genes encode proteins that are calmodulin-binding proteins involved in a variety of cellular processes. However, systematic characterization of this gene family in soybean (Glycine max L. Merr.) has not been yet reported. In this study, we identified MLO domain-contained members in soybean and examined their expression under phytohormone treatment and abiotic stress conditions. A total of 20 soybean Mlo genes were identified (GmMlo1-20), which are distributed on 13 chromosomes, and display diverse exon-intron structures. Phylogenetic analysis indicated that the Mlo family can be classified into four subfamilies. Sequence comparison was used to reveal the conserved calmodulin-binding domain (CaMBD) in GmMLO proteins. The expression of GmMlo genes was influenced by various phytohormone treatments and abiotic stresses, suggesting that these Mlo genes have various roles in the response of soybean to environmental stimuli. Promoter sequence analysis revealed an overabundance of stress and/or phytohormone-related cis-elements in GmMlo genes. These data provide important clues for elucidating the functions of genes of the Mlo gene family.
  • Kazunori Maehara, Takayuki Murata, Naoki Aoyama, Kenji Matsuno, Kyoich ...
    原稿種別: Full paper
    2012 年 87 巻 2 号 p. 99-106
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    Previous reports have suggested that the Nucleoporin 160 (Nup160) gene of Drosophila simulans (Nup160sim) causes the hybrid inviability, female sterility, and morphological anomalies that are observed in crosses with D. melanogaster. Here we have confirmed this observation by transposon excision from the P{EP}Nup160EP372 insertion mutation of D. melanogaster. Null mutations of the Nup160 gene resulted in the three phenotypes caused by Nup160sim, but revertants of the gene did not. Interestingly, several mutations produced by excision partially complemented hybrid inviability, female sterility, or morphological anomalies. In the future, these mutations will be useful to further our understanding of the developmental mechanisms of reproductive isolation. Based on our analyses with the Nup160sim introgression line, the lethal phase of hybrid inviability was determined to be during the early pupal stage. Our analysis also suggested that homozygous Nup160sim in D. melanogaster leads to slow development. Thus, Nup160sim is involved in multiple aspects of reproductive isolation between these two species.
  • Yanhong Cao, Caijuan Li, Jian Yan, Feng Jiao, XiaoYun Liu, Karen A. Ha ...
    原稿種別: Full paper
    2012 年 87 巻 2 号 p. 107-113
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    Previously, we identified a major quantitative trait locus (QTL) on mouse chromosome 1 that regulates the susceptibility to arthritis in an F2 population generated from arthritis-prone BALB/c and arthritis-resistant DBA/1 mice deficient for interleukin-1 receptor antagonist. To further select candidate genes for the QTL, we analyzed the expression patterns of arthritis in 38 F2 individuals and compared the expression levels of key candidate genes to the parental strains. Two distinct subpopulations of arthritic mice were identified in the 38 F2 mice. One subgroup of diseased mice was characterized by myeloid cell dominant inflammation, whereas the other was mainly associated with increased anti-apoptotic activities of inflammatory cells. Several differentially expressed important candidate genes in parental strains in the QTL region are relevant to myeloid cell, apoptotic activities, or to both. About one-quarter of those genes have been previously linked to arthritis in literature. The present study reveals two distinct subpopulations of arthritic mice with spontaneous arthritis due to deficiency for interleukin-1 receptor antagonist, suggesting that genes with function relevant to myeloid cell and/or apoptotic activities are most likely the key candidate genes for the QTL.
  • Seiji Kato, Kazunari Hashiguchi, Kento Igarashi, Takahito Moriwaki, Sh ...
    原稿種別: Full paper
    2012 年 87 巻 2 号 p. 115-124
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    Oxidatively damaged bases in DNA can cause cell death, mutation and/or cancer induction. To overcome such deleterious effects of DNA base oxidation, cells are equipped with base excision repair (BER) initiated by DNA glycosylases. Endonuclease III (Nth), a major DNA glycosylase, mainly excises oxidatively damaged pyrimidines from DNA. The aims of this study were to obtain an overview of the repair mechanism of oxidatively damaged bases and to elucidate the function of BER in maintaining genome stability during embryogenesis and development. In this study, we used the ascidian Ciona intestinalis because at every developmental stage it is possible to observe the phenotype of individuals with DNA damage or mutations. Sequence alignment analysis revealed that the amino acid sequence of Ciona intestinalis Nth homologue (CiNTH) had high homology with those of Escherichia coli, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Caenorhabditis elegans and human Nth homologues. It was evident that two domains, the Helix-hairpin-Helix and 4Fe-4S cluster domains that are critical regions for the Nth activity, are well conserved in CiNTH. CiNTH efficiently complemented the sensitivity of E. coli nth nei mutant to H2O2. CiNTH was bifunctional, with DNA glycosylase and AP lyase activities. It removed thymine glycol, 5-formyluracil and 8-oxoguanine paired with G from DNA via a β-elimination reaction. Interestingly, the N-terminal 44 amino acids were essential for the DNA glycosylase activity of CiNTH.
  • Hidenori Tachida
    原稿種別: Full paper
    2012 年 87 巻 2 号 p. 125-135
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    Glacial and interglacial cycles are considered to have caused the fragmentation and admixture of populations in many organisms. A simple model incorporating such periodic changes of the population structure is analysed in order to investigate the behaviour of neutral genetic variation at one and two loci. The equilibrium is reached very quickly in terms of cycles if the length of a cycle is long, as would be expected of the glaciation cycles. Heterozygosity and linkage disequilibrium are shown to depend on the length of time of the fragmented and admixed phases, population sizes, and number (n) of subpopulations in the fragmented phase. If the population size is small in the fragmented phase and its duration is long, the squared correlation coefficient of two loci (a measure of linkage disequilibrium) just after the admixture is approximated by 1/(n–1) for n > 1. After admixture, the correlation decays at a rate of approximately twice the recombination rate. Therefore, if post-glaciation admixture created linkage disequilibrium, we expect to observe linkage disequilibrium even between moderately linked loci, and its decay pattern along the chromosome is very different from that in a random mating population at equilibrium. This is especially true in organisms with long generation times such as trees.
Short communication
  • Ryusuke Matsuda, Julio C. M. Iehisa, Shigeo Takumi
    原稿種別: Short communication
    2012 年 87 巻 2 号 p. 137-143
    発行日: 2012年
    公開日: 2012/07/13
    ジャーナル オープンアクセス HTML
    Available information on genetically assigned molecular markers is not sufficient for efficient construction of a high-density linkage map in wheat. Here, we report on application of high resolution melting (HRM) analysis using a real-time PCR apparatus to develop single nucleotide polymorphism (SNP) markers linked to a hybrid necrosis gene, Net2, located on wheat chromosome 2D. Based on genomic information on barley chromosome 2H and wheat expressed sequence tag libraries, we selected wheat cDNA sequences presumed to be located near the Net2 chromosomal region, and then found SNPs between the parental Ae. tauschii accessions of the synthetic wheat mapping population. HRM analysis of the PCR products from F2 individuals’ DNA enabled us to assign 44.4% of the SNP-representing cDNAs to chromosome 2D despite the presence of the A and B genomes. In addition, the designed SNP markers were assigned to chromosome 2D of Ae. tauschii. The order of the assigned SNP markers in synthetic hexaploid wheat was confirmed by comparison with the markers in barley and Ae. tauschii. Thus, the SNP-genotyping method based on HRM analysis is a useful tool for development of molecular markers at target loci in wheat.
feedback
Top