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Volume 51 (1976)
- Issue 6 Pages 377-
- Issue 5 Pages 297-
- Issue 4 Pages 223-
- Issue 3 Pages 149-
- Issue 2 Pages 71-
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Volume 51, Issue 5
Displaying 1-7 of 7 articles from this issue
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HITOSHI ASAMI, NOBUMICHI INOMATA, MASASUKE OKAMOTO1976 Volume 51 Issue 5 Pages 297-303
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSChromosome number was examined in eight strains of the callus cells in Secale cereale L. with and without B-chromosome.
Variation of chromosome number was small without B-chromosome and was large with B-chromosomes (one, two and four B-chromosomes).
Selective functions might exist in B-chromosome of callus cells in Secale cereale L.View full abstractDownload PDF (1892K) -
II. FECUNDITY AND MORTALITYSEIDO OHNISNI1976 Volume 51 Issue 5 Pages 305-314
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSBy using homozygous or heterozygous flies of two strains of Drosophila melanogaster, the effect on fecundity (egg production) of adult density and fluctuating temperature were investigated. The results indicated that: (1) Fecundity was strongly influenced by adult density and by the temperature condition, i.e., egg production was lower in the higher density and under the fluctuating temperature (a 20°C-30°C cycle per day) in both strains. (2) The mean number of eggs laid by heterozygous flies was larger than that laid by homozygous flies. However, the decrease in oviposition under the fluctuating temperature was more pronounced for heterozygous flies than for homozygous ones of both strains. (3) In order to examine the change of the daily egg production, the regression coefficients of mean number of eggs on day and the (c)-values were estimated under various conditions. The (c)-value and the absolute value of the regression coefficient were larger for homozygous flies, in the crowded condition and under the constant temperature than for heterozygous ones, in the uncrowded conditions and under the fluctuating one, respectively. (4) Mortality was related to the coefficient of regression of daily egg production on time. Therefore, mortality (longevity) can be predicted from this coefficient. Also, mortality was different between the sexes, and the difference was affected by temperature. (5) The effect of the fluctuating temperature on fecundity and mortality was similar to that of fluctuating light on them. Some problems arising from the results were discussed.View full abstractDownload PDF (1004K) -
MASANAO MICHINOMAE1976 Volume 51 Issue 5 Pages 315-326
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe aspects of degeneration in the Bar eye discs at various developmental stages of Drosophila melanogaster was elucidated microscopically and biochemically. Acid phphosatase was identified histochemically in lysosomes or their derivertives in the degenerating area of the 85-95 hour eye discs. The enzyme reaction appeared to localize selectively in the single membrane-bounded structure or myelin-like figure. The cell debris probably resulting from the resolving process, fail to demonstrate any enzyme activity at the prepupal stage.
Biochemical data indicated that the maximum activities of acid phosphatase were shown in eye discs at the 95-hour stage. This is in contrast to the weak acid phosphatase activity detected in eye discs of prepupal stage. However, whole larval homogenates showed maximum value of acid phosphatase activity at the same stage and the post embrionic development. This causal association of increased enzyme activity and histochemical observation in the resolving process of the eye discs suggests that the process of degeneration may be mediated by the lysosome activity, either by the formation of lysosomes or by the synthesis of hydrolytic enzymes. These lysosomes or activities of lysosomal lytic enzyme were reduced by treatment with acetamide. These data suggest that acetamide may act to inhibit the formation of lysosome or the synthesis of hydrolytic enzyme in the Bar eye discs.View full abstractDownload PDF (2992K) -
II. SEED INVIABILITY INDUCED BY THE ALIEN CYTOPLASMSSEIICHI TSUJI, MINORU MURATA1976 Volume 51 Issue 5 Pages 327-336
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSIn order to clarify the specific nucleo-cytoplasmic interactions between the D genome chromosomes in common wheat and the Ae. squarrosa, Ae. cylindrica and Ae. crassa cytoplasms, we produced three aneuploid series of the D genome chromosomes, i. e., ditelosomics, monosomics and nullitetrasomics, of Triticum aestivum L. cv. Chinese Spring with the above three cytoplasms. And, the seed fertilities of these lines were investigated.
Seven ditelosomic lines with the squarrosa cytoplasm had high fertilities. However, ditelo-2Dα and -7DS with the crassa cytoplasm showed highly reduced fertilities. Their fertility reduction was mainly due to pistillody.
We produced 18 monosomics of the D genome chromosomes with the three alien cytoplasms, except mono-5D with the squarrosa cytoplasm and mono-2D and -5D with the crassa cytoplasm. Every monosomic line had high seed fertility, although several lines showed slight reduction when compared with the corresponding normal monosomic lines.
By backcrossing the three cytoplasm substitution lines with nullitetrasomics, we attempted to obtain the nullitetrasomics with the alien cytoplasm. As a result, twelve lines, which were all fertile, were obtained. However, chromosomal segregations were biased particularly in the crosses between mono-1D tri-1A plants with the three alien cytoplasms (_??_) and the normal nulli-1D tetra-1A's (_??_), and none of nulli-1D tri-1A's and nulli-1D tetra-1A's was obtained. Furthermore, mono-1D tri-1A's with these cytoplasms showed extreme reduction of seed fertility when pollinated by nulli-1D, while normal seed fertility by the disomic. Ditelo-1DL plants with those alien cytoplasms were normally fertile. Taking all these results in consideration, we concluded that the viability gene(s) against the three alien cytoplasms is located on the long arm of the 1D chromosome of common wheat.View full abstractDownload PDF (918K) -
HOMARE KUWANA, SACHIKO IMAEDA1976 Volume 51 Issue 5 Pages 337-345
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSAcetate-requiring mutant strain 163 was investigated and compared with suc mutants. Growth and enzyme characteristics of the strain are similar to those of suc mutants. It is probable from genetic analyses that strain 163 carries a paracentric inversion near the mating type locus, between leu-4 and suc genes on the left arm of the first linkage group. The gene suc seems to be separated into two parts by the inversion, and this may be the reason for the acetate requirement and the similarity of strain 163 to suc mutants. Revertants were obtained from strain 163. All six revertants proved to be due to suppressor mutations. At least two different suppressor genes are involved. All the revertants produced spheroplasts and yeast-like morphology when they were cultivated with vigorous aeration in medium without acetate, while they showed normal mycelial structure in medium with acetate.View full abstractDownload PDF (1233K) -
YOSHIHISA FUJIO1976 Volume 51 Issue 5 Pages 347-354
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSHomozygous Cp/Cp embryos produced by the Cp (WL-G) strain all die by the 10th day of incubation. Expression of the lethal action of the CP gene was examined in crosses of various breeds with the Cp (WL-G) strain. The F1 heterozygous Cp/+chickens obtained by crossing the Nagoya and Silkie breeds with the CP (WL-G) strain produced high percentages of viable homozygous CP/CP embryos. However, crosses of the Brown Leghorn, Black Minorca, and New Hampshire with the Cp (WL-G) strain did not produce homozygous CP/CP embryos.
The Cp (NG-A) and Cp (NG-N) strains produce viable homozygous Cp/Cp embryos. Two reciprocal crosses of these strains with the CP (WL-G) strain showed different percentages of viable Cp/Cp embryos, indicating that expression of the Cp gene depended on the maternal genetic constitution. Results on two reciprocal crosses of the NG-N strain with the Cp (WL-G) strain suggested that the maternal genetic constitution appearing in viable homozygous Cp/Cp embryos was brought about by dominant and autosomal genes. Expression of the Cp gene also depended on the period of egg laying, suggesting that some substance(s) lowering the lethal action of the Cp gene was introduced into the cytoplasm of the eggs by the mother hens.View full abstractDownload PDF (1069K) -
MASATOSHI NEI, SHOZO YOKOYAMA1976 Volume 51 Issue 5 Pages 355-369
Published: 1976
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe effects of random fluctuation of selection intensity on the expected number of heterozygous codons, average heterozygosity, and the relationship between gene frequency and heterozygosity are studied, assuming that the fluctuation of selection intensity is a random noise. In small populations these effects are relatively small, and the genetic variability in a population is determined mainly by the mutation rate and population size. In large populations, however, even a small amount of random fluctuation reduces the genetic variability to a considerable extent. A formula for the expected number of segregating codons per locus is also worked out. Roughly speaking, the effect of random fluctuation of selection intensity on this parameter is similar to that on the expected number of heterozygous codons per locus. In addition to the above studies, mathematical models of random fluctuation of selection intensity in diffusion approximations are discussed. It is shown that data on molecular evolution and polymorphism are more consistent with the predictions from the hypothesis that temporal fluctuation of selection intensity is a “random noise” than those from the alternative hypothesis that it is a “stabilizing factor for gene frequency.”View full abstractDownload PDF (1374K)
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