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Volume 49, Issue 1
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TAKATADA KAWAHARA1974 Volume 49 Issue 1 Pages 1-9
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSBilateral asymmetry in the transverse processes (TP) of the cervical vertebrae in domestic chickens was investigated. The asymmetry was classified into two categories; directional and fluctuating. The directional asymmetry was measured by the difference between the lengths of the two TP, that is, left minus right. The fluctuating asymmetry, however, was defined as asymmetry due to chance fluctuation in the development of left and right TP and was measured by the bilateral asymmetry remaining after subtraction of the average directional asymmetry of each strain. If the degree of fluctuating asymmetry in a single bird is a, then a=|(left-right)-average(left-right)|. Since a was found not to distribute normally, it has been transformed to A=log10[(a+0.1)2]. The birds investigated were 16-month old White Leghorn females of 6 inbred, one closed and 5 F1 hybrid strains. The lengths of the left and right TP (4) of the sixth to ninth cervical vertebrae were measured.
A comparison of the differences between the directional asymmetries of the four vertebrae was found to be statistically significant, but there were no differences among strains. The left TP was usually longer than the right, the mean difference being 0.126mm. It appears that this asymmetry is directional rather than random.
Variation in fluctuating asymmetry among strains was highly significant: the F1 hybrids were less asymmetric than their inbred parents. If we assume that the fluctuating asymmetry in length of the TP's of the cervical vertebrae is a result of developmental instability in the bird, it is reasonable to expect that heterozygosity might reduce this instability. This was found in this study.
Directional and fluctuating asymmetries are positively correlated with each other (r=0.696). In other words, those vertebrae which showed high directional asymmetry had simultaneosly high fluctuating asymmetry. Correlation between body weight and TP length was estimated to be 0.789, whereas body weight was not significantly correlated with either directional or fluctuating asymmetry. It should be mentioned that neither directional nor fluctuating asymmetry is significantly correlated with TP length or with the difference between the lengths of the TP of the F1 hybrids and the corresponding mid-parental values.View full abstractDownload PDF (940K) -
TOSHIHIKO OKADA1974 Volume 49 Issue 1 Pages 11-23
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSStudies were made on mutants from a deoxyriboside-sensitive Thy- strain selected for their ability to grow on thymidine at high concentration, which still require a low concentration of thymine for growth. They were found to be divided into two groups with regard to the inducibilities of their thymidine phosphorylase and purine nucleoside phosphorylase. In one group these enzymes were inducible (inducible type) and in the other group they were not (non-inducible type). All the mutants showed lower thymidine phosphorylase activity than the parent strain. However, there were striking quantitative differences between non-inducible type strains, in the level of activity of purine nucleoside phosphorylase. The only exception was strain T429 which showed such high purine nucleoside phosphorylase activity that the enzyme seemed to be constitutive. All these thymidine-resistant mutants lacked deoxyriboaldolase. Some non- inducible type mutants also contained no phosphodeoxyribomutase, while others, as well as inducible type mutants contained this enzyme.
The gene(s) involved in the mutation causing these changes was mapped preliminary by transduction with phage Plc on a site which was closely linked to thr at the opposite side to leu where the deo-operon is present. This gene was concluded to be in the drm gene in some of the non-inducible type mutants, and not to be in the drm gene in the other non-inducible type mutants and in all inducible type thymidine-resistant utants.View full abstractDownload PDF (1247K) -
KAZUKO ITO1974 Volume 49 Issue 1 Pages 25-31
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSIn a previous study (Minamori and Ito 1971) the extrachromosomal element [delta b] was shown to induce recessive lethal, semilethal and visible mutations on 2nd chromosomes. In this study the mutagenic action of this delta to X chromosomes as examined. The frequency of recessive lethals induced was 0.08%, being four times the spontaneous mutation rate (0.02%). The difference, however, was statistically insignificant. Accordingly, the conclusion may be that [delta b] has no effective mutagenicity for X chromosomes. The differential behaviors of X and 2nd chromosome to mutagenicity of [delta b] were discussed from the aspect of natural selection.View full abstractDownload PDF (734K) -
TSUNEYUKI YAMAZAKI1974 Volume 49 Issue 1 Pages 33-36
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (293K) -
TAKASHI IKEJIMA, TAKUJI TAKEUCHI1974 Volume 49 Issue 1 Pages 37-43
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSAn attempt was made to demonstrate a change in the electrophoretic pattern of tyrosinase in the neo-natal stage in mice with different genotypes at a locus. In agouti as well as non-agouti animals, both T1 and T2 bands appeared on one or two days after birth and persisted until the 9th to 10th day after which only the T1 band remained. On the other hand, only the T1 band was observed in the yellow mice throughout the post-natal stages. It is conceivable that either of the processing steps, T1 to T2 or the nascent tyrosinase to T2 is blocked by the product of Ay gene, resulting in phaeomelanin formation.View full abstractDownload PDF (1021K) -
HISASHI YOSHIDA, HIKOYUKI YAMAGUCHI, YASUSHI TAKANO1974 Volume 49 Issue 1 Pages 45-47
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (404K) -
TOSHIDE H. YOSIDA, KAZUO MORIWAKI, TOMOKO SAGAI1974 Volume 49 Issue 1 Pages 49-52
Published: 1974
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (1098K)
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