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Volume 49 (1974)
- Issue 6 Pages 353-
- Issue 5 Pages 265-
- Issue 4 Pages 179-
- Issue 3 Pages 113-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 49, Issue 2
Displaying 1-7 of 7 articles from this issue
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HIDEO KOGA, TADAO HORIUCHI1974 Volume 49 Issue 2 Pages 57-62
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS(1) Mutants of phage λ occurred in gene cI which show clear plaque at high temperature but normal turbid plaque at low temperature, were isolated. (2) Lysogens for cItsA are induced irreversibly even at low temperature after heat treatment, and lysogens for λcItsB are induced only when the cultures are heated at a high temperature during growth. These results confirmed those of Lieb (1966) and Horiuchi and Inokuchi (1967). (3) λcItsA and λcItsB mutants were all mapped in the left and right part of gene cI, respectively, as reported by Lieb (1966). (4) Some λcItsB which are located on the right-end region of gene cI complement λcItsA for lysogenization.View full abstractDownload PDF (554K) -
NORIAKI EBITANI1974 Volume 49 Issue 2 Pages 63-70
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSOn 22 homozygous genotypes which are different in the combination of isozyme alleles at the Est-α and Est-β loci, both highly polymorphic in natural populations, two kinds of esterase activities were compared. Most of the esterase activities are controlled by these two esterase loci. The activity is highest in the genotypes which have two active alleles at both Est-α and Est-β loci. The null strain which is homozygous for silent alleles at both loci has weakest activity, a part of which may be ascribed to other genetic systems. The activity of genotypes which are homozygous for active alleles at only Est-α or Est-β locus is between these two groups. Esterase activity increases additively in proportion to the number of active alleles at each locus.View full abstractDownload PDF (758K) -
NORIAKI EBITANI1974 Volume 49 Issue 2 Pages 71-80
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSIn order to obtain further information about the mechanisms which maintain the remarkable isozyme polymorphisms at the Est-β locus of D. virilis, several components of fitness were compared among electrophoretically different genotypes. Esterase activities are statistically the same among three genotypes (BB, BD and DD) with similar genetic backgrounds.
Under near optimal culture conditions, the following components were examined separately for three genotypes: fecundity, hatchability, egg-to-adult viability and developmental time. No significant differences were observed among genotypes for any of these components.
Under competitive conditions in which two or three genotypes coexist in a culture vial, relative egg-to-adult viability of each genotype was estimated at several genotype frequency levels. Except for one case in which a rare DD genotype was more viable than abundant ones, the relative viability did not differ among coexisting genotypes and no clear and consistent evidence of frequency-dependent selection was obtained.
The results of the present experiments suggested that esterase isozyme variants are of no great adaptive significance, so far as they are at the same level of enzyme activity.View full abstractDownload PDF (1077K) -
HIKOYUKI YAMAGUCHI1974 Volume 49 Issue 2 Pages 81-85
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDormant seeds of two partially asynaptic strains, K-642 and K-648, in which 2 to 8 univalents were present at the first metaphase of meiosis, and a normal cultivar Kinmaze were irradiated with gamma rays of 0 to 30kR. The survival rate at maturity of the X1 plant was reduced to a marked extent in K-642 and K-648 compared with Kinmaze. The mean seed setting in K-648 was slightly less than in Kinmaze. The incidence of chlorophyll mutations in Kinmaze increased linearly with the radiation dose. In contrast, the mutation frequency in K-648 was found to increase more rapidly than a single power of the dose of gamma rays. Supposing that the loose association of homologous chromosomes in somatic cell is correspondent with the failure of hromosome pairing at meiosis, the results obtained in this experiment provide the evidence of a common basis for repair and recombination mechanisms even in rice.View full abstractDownload PDF (458K) -
YOSHIHISA FUJIO, TOHRU SHIBUYA1974 Volume 49 Issue 2 Pages 87-91
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe Creeper (Cp) gene from the Jitokko was introduced into the inbred strains, WL-G and NG-A, and two strains Cp (WL-G) and Cp (NG-A) were established in the gradings by successive backcrosses.
In the Cp (NG-A) strain, heterozygous parents produced the expected homozygous Cp/Cp embryos, 83.2% of which was viable on the 10th day of incubation and in the Cp (WL-G) strain viable homozygous Cp/Cp embryos were not obtained. Although the Cp (NG-A) showed high percentage of viable homozygous Cp/Cp embryos, the percentage decreased as maternal ages increased.View full abstractDownload PDF (413K) -
SEI-ICHI MATSUI1974 Volume 49 Issue 2 Pages 93-96
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (1364K) -
TAMOTSU HASHIMOTO, KENICHI MATSUBARA1974 Volume 49 Issue 2 Pages 97-101
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (533K)
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