巻号一覧
66 巻, 6 号
選択された号の論文の6件中1～6を表示しています
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James F. CROW1991 年 66 巻 6 号 p. 669-682
発行日: 1991年
公開日: 2006/06/10
ジャーナル フリーProfessor Mukai was my postdoctoral associate for more than two years, from June 1965 through July 1967. In this article, I discuss mainly the work done during that period.
Mukai's best known accomplishment was to demonstrate that the total deleterious mutation rate is considerably higher than was previously thought, due to the very high rate of mutation of viability-depressing polygenes. These are at least 25 times as frequent as lethals. These experiments, utilizing a mutation-accumulation scheme, were clever in design, meticulous in execution, and heroic in scope. In related experiments he showed that the typical viability-reducing mutation is deleterious in the heterozygous as well as homozygous state. From the viability experiments he was able to infer that there is strong heterozygous selection for fitness, comparable to that for lethals.
All of Mukai's research was characterized by a willingness to undertake problems that involved enormous numbers of Drosophilae and many hours of work. His ability to plan such experiments and to see that they were carried out carefully was a rare gift, one that the genetics community will sorely miss.
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Etsuko T. MATSUURA1991 年 66 巻 6 号 p. 683-700
発行日: 1991年
公開日: 2006/06/10
ジャーナル フリーPDF形式でダウンロード (2825K)
ARTICLES
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Muneo MATSUDA1991 年 66 巻 6 号 p. 701-707
発行日: 1991年
公開日: 2006/06/10
ジャーナル フリーThe frequency of recessive lethals in the 2nd chromosome was examined in two mutator stocks of Drosophila ananassae, ca and ca ; px. They are characterized respectively by possessing an extrachromosomal clastogenic mutator in males, and by the retrotransposon "tom", which induces Om mutability only in females. The frequencies of recessive lethal mutations in the 2nd chromosome among progenies from males and females of the ca ; px stock are 0.35 and 0.34 percent, respectively. Similarity of these frequencies indicates that tom does not induce recessive lethals in females. In contrast to the ca ; px stock, the frequency of recessive lethals in males of the ca mutator stock was estimated to be 1.54 percent for the 2nd chromosome. No visible mutants except Minutes were recovered. Some recessive lethals derived from ca stock males were associated with chromosomal rearrangements. Being consistent with its high rate of Minute mutation it was demonstrated that the ca clastogenic mutator also induced recessive lethals.
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Kozi OKAMOTO, Katsunori SUZUKI, Kazuo YOSHIDA1991 年 66 巻 6 号 p. 709-718
発行日: 1991年
公開日: 2006/06/10
ジャーナル フリーMitochondrial DNAs from the ascosporogenous yeasts S. exiguus, S. kluyveri and H. wingei were prepared by a new rapid method without CsCl isopycnic centrifugation. The mtDNA RFLPs were identified and clearly distinguished each species from the other. The physical maps were constructed by single and double digestion with nine restriction endonucleases. The location of rRNA genes was assigned to the maps by Southern hybridization with synthetic consensus probes. The genome sizes of these mtDNAs were estimated to be 45 kb for S. exiguus, 54kb for S. kluyveri and 27kb for H. wingei. The mtDNA RFLP analysis indicates a phylogenetic relationship among these yeasts. This indicates that S. cerevisiae is closer to H. wingei than S. kluyveri. However, the derived phylogenetic tree is completely consistent with that which was previously constructed on amino acid replacement in mating pheromones and electrophoretic karyotypes (Yoshida et al., 1989).
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Hiroyuki KANZAKI, Masaharu TAKEDA, Toshiaki KAMEYA1991 年 66 巻 6 号 p. 719-724
発行日: 1991年
公開日: 2006/06/10
ジャーナル フリー2.0kb Hind III fragment isolated from cytoplasmic male-sterile carrot mitochondria, designated PKT5, was hybridized to ORF13 which is the coding region of a unique polypeptide in maize CMS (Dewey et al., 1986). Sequence analysis indicated that PKT5 is consisted of 3 domains. Domain 1 was identical to the 5'-flanking region of atp6 in maize CMS-TURF2H3 sequence (Dewey et al., 1986). Domain 2 contained a novel ORF encoding 72 amino acids, which was extremely homologous to the amino-terminal 67 amino acids of the unique ORF13 in maize CMS. Domain 3 except an amino acid change (Ile87=ATT for Asn87=AAT), was identical to ORF25 polypeptide in maize CMS. Connective sequences of these 3 domains were also highly homologous to the maize CMS-TURF2H3 sequence. Out of 7 recombination points in maize CMS-TURF2H3 sequence, at least 4 points were conserved in PKT5 sequence.
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Ko HARADA, Shin-ichi KUSAKABE, Terumi MUKAI1991 年 66 巻 6 号 p. 725-737
発行日: 1991年
公開日: 2006/06/10
ジャーナル フリーPopulation structure concerning P element activity was investigated in two natural Drosophila populations. These populations are very different as far as in the viability spectrum is concerned. In one population, the Raleigh, United States population, genetic loads related to viability have been kept at a fairly high level. In the other population, the Nagasaki, Japan, population, the genetic loads tend to be stable at very low levels. In the Raleigh population it is estimated that on the average 4 copies of intact P elements that possess transposase activity exist in the genome. On the other hand only 0.7 complete copies are estimated to exist in the genome of the Nagasaki population. Heterogeneity in the P element copy number and significant positive linkage disequilibrium among occupied sites were detected in the Raleigh population. Our results, with some evidences which indicate that high mutation rate was caused by the P element, suggests that the large genetic loads in the Raleigh population are caused by the rapid invasion of P element in this population.
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