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Volume 68 (1993)
- Issue 6 Pages 521-
- Issue 5 Pages 353-
- Issue 4 Pages 243-
- Issue 3 Pages 167-
- Issue 2 Pages 83-
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Volume 68, Issue 4
Displaying 1-7 of 7 articles from this issue
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ARTICLES
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Tsutomu KISHI, Kin-ichiro MIURA, Kouji MATSUMOTO, Hideo HIROKAWA1993 Volume 68 Issue 4 Pages 243-255
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSTwo different expression systems of genes of primer proteins (pE for phage M2, and p3 for φ29) were constructed to study the protein primed DNA replication of Bacillus phages M2 and φ29. In one system, expression of the genes was under the control of the inducible spac promoter, whereas in the other system, the expression was under the control of the constitutive promoter in plasmid pUB110. Complementation tests in vivo were performed between the primer proteins expressed by these systems and mutant phages having suppressor sensitive mutations in the genes of the primer proteins. The phages M2 susE and φ29 sus3 were complemented by pE and p3 expressed by the systems, respectively. However, the complementation and apparent phage DNA synthesis were not detected in the combinations between susE of phage M2 and p3 of phage φ29, and vice versa. Although pE and p3 proteins exhibited structurally and functionally similar characteristics, these proteins showed species specificity in the protein primed DNA replication of bacteriophages M2 and φ29.
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Jai Pal GUPTA, Tadashi AOTSUKA, Akemi INABA, Osamu KITAGAWA1993 Volume 68 Issue 4 Pages 257-264
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSDrosophila bipectinata and D. malerkotliana are members of the bipectinata species complex of the ananassae subgroup in the melanogaster species group of Drosophila. The mtDNA from 18 isofemale strains of these species was analyzed, using 13 restriction endonucleases. Altogether, eight mtDNA haplotypes were detected, of which the haplotype 1B was shared by the two species. Restriction cleavage map of mtDNA of these species was constructed. The net nucleotide substitutions per site calculated between these species was found to be 0.0002. This value appeared to be relatively much lower than expected at the interspecific level, even lower than that reported between two subspecies of Drosophila despite both being good species. This extreme closeness of their mtDNAs is discussed in the light of recent findings.
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Junpei ISHIGURO, Nozomi YAMADA1993 Volume 68 Issue 4 Pages 265-276
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSThe cps8 mutation which confers supersensitivity to a spindle poison, Isopropyl N-3-chlorophenyl carbamate (CIPC), in the fission yeast Schizosaccharomyces pombe was investigated. The cps8 mutant accumulated enlarged multinucleate cells in the stationary phase under normal growth conditions. The mutant was highly lethal at 36.5°C in a fresh growth medium but not in a saline solution where the cell cycle ceases quickly. Lethality at high temperature was significantly suppressed by cdc1 or nda2 mutation which blocks nuclear division, but not by hydroxyurea treatment or cdc22 mutation which blocks DNA synthesis. A cdc10 cps8 double mutant remained lethal to high temperature, suggesting this double mutant to bypass the requirement for cdc10+ indispensable for the cell cycle start in a wild-type cell. After being transferred to a fresh medium at 36.5°C, the multinucleate cells rapidly divided with aberrant nuclear segregation. Thus, cps8 mutation allows cells to undergo mitosis without DNA replication at the restrictive temperature. The cps8 gene was mapped on the left arm of chromosome II closely linked to but distinct from cdc2 locus.
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Sadao ICHIKAWA, Akihiko YAMAGUCHI, Mikiko OKUMURA1993 Volume 68 Issue 4 Pages 277-292
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSYoung inflorescences of Tradescantia clones KU 27 and BNL 4430, the both of which are blue/pink heterozygotes and have been demonstrated to be highly sensitive to alkylating agents, were exposed either to aqueous solutions of methyl methanesulfonate (MMS) for 16hr alone (at 0.005 to 0.02% for KU 27 and at 0.005% for BNL 4430) or to acute 150 kVp X rays alone (161 to 531 mGy for KU 27 and 501 to 976 mGy for BNL 4430), or in combinations (134 to 448 mGy for KU 27 and 458 to 865mGy for BNL 4430 after the 0.005% MMS treatment). The induced somatic pink mutation frequencies per hair-cell division were studied and compared, and clone BNL 4430 was found to be nearly two times more sensitive to MMS than clone KU 27, while the X-ray-induced mutation frequencies in the latter was about 1.5 times higher than those in the former. The lower sensitivity to MMS of clone KU 27 (as compared with BNL 4430) was nevertheless about 5.6 times higher as compared with the responses of clone BNL 02 to MMS reported earlier, proving the high sensitivities of the two clones used in the present study. Clear synergistic effects of MMS and X rays were observed in the both clones, indicating that the mechanisms of inducing mutations are common at least in part between MMS and X rays.
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Minoru IKEDA, Akihiro KIJIMA, Yoshihisa FUJIO1993 Volume 68 Issue 4 Pages 293-302
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSNei's (1972) genetic distance were estimated among 21 populations of the common freshwater shrimp Paratya compressa improvisa, living in the northern part of Japan. The estimates were based on examination of 18 enzyme loci by starch-gel electrophoresis. These shrimp populations were genetically classified into three geographic groups on the basis of predominating alleles typical for two loci Fdp-1 and Fdp-2. The "Kanto group" consisted of individuals having Fdp-1a and Fdp-2c, the "Japan Sea group" having Fdp-1b and Fdp-2a, and the "Pacific Ocean group" having Fdp-1b and Fdp-2c. Nei's genetic distance among the three different geographic groups, varied from 0.0572 to 0.2136. Average genetic distances were 0.1001 between Pacific Ocean and Japan Sea groups, 0.0851 between Pacific Ocean and Kanto groups, and 0.1990 between Japan Sea and Kanto groups. These values of genetic distance among the three groups are comparable with those among different subspecies.
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Ohmi OHNISHI1993 Volume 68 Issue 4 Pages 303-316
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSAllozyme variability at 19 loci affecting 12 enzymes was analyzed electrophoretically in 21 populations from Europe and six populations from the silk road. Most of the populations were polymorphic at seven loci, Dia-2, Got-2, Mdh-1, Mdh-3, Pgm-1, Pgm-2 and Sdh-1. As compared with Chinese populations, European populations have completely lost variability at Adh and 6-Pgdh-1. Populations from southern Europe have less variability than those from other parts of Europe. They have lost variability at Pgm-2 and have a greatly reduced frequency of the F allele at Mdh-1; occasionally, however, they show an increase in the frequency of the U allele at the Got-2 locus. Southern European populations show an increase in the det allele and in grey colored varieties. As a group, European populations show the smallest genetic distance with populations from the silk road and northern China. Combining these genetic findings with written documents and archeological evidence, I conclude that European buckwheat came from northern China via the silk road, and that it changed in many respects within the last 500 years.
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Ohmi OHNISHI1993 Volume 68 Issue 4 Pages 317-326
Published: 1993
Released on J-STAGE: December 03, 2004
JOURNAL FREE ACCESSBy adding data on allozyme variability in 35 populations from southern and central China, I completed a worldwide survey of allozyme variability in common buckwheat. The following remarks were born out from the survey. (1) At all loci, allele frequency does not vary so much among the populations from a wide range of Asian countries. (2) Most of the evolutionary events which might occur during the spread of buckwheat cultivation are the losses of variant alleles by random drift. (3) Drastic changes of gene frequency have been observed only in marginal populations, in Kumaun, Garwhal hills and Kashmir in India and in southern Europe. (4) Cultivated buckwheat has more genetic variability than the natural populations of the wild ancestor. Large population size and complete panmixis of a population and enough migration between populations may be responsible for observation (1) and may also have led to the accumulation of variant alleles in cultivated populations, i.e. observation (4). Random drift, such as founder effect, took place only in marginal populations, accounting for observations (2) and (3). Buckwheat provides an example that contradicts Vavilov's assertion; it says that the center of genetic diversity of a cultivated plant is the place of its origin. Buckwheat is apparently monocentric, but the pattern of variation suggests domestication over a wide area, instead of progressive decline in diversity from the center of origin to the periphery. The structure of buckwheat populations and their mating system are mainly responsible for this unexpected result.
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