All issues
Successor
Volume 56 (1981)
- Issue 6 Pages 565-
- Issue 5 Pages 447-
- Issue 4 Pages 349-
- Issue 3 Pages 241-
- Issue 2 Pages 105-
- Issue 1 Pages 1-
Volume 56, Issue 4
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Sumiyo ENDO, Nobuo TAKAGI1981 Volume 56 Issue 4 Pages 349-356
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSWe examined the replication behavior of the X chromosome in diploid 8.5- and 9.5-day parthenogenetic LT/Sv mouse embryos showing growth retardation and morphological anomalies. A single late replicating X chromosome was found in the extraembryonic as well as in the embryonic regions. However, the frequency of cells with a late replicating X was significantly lower in the extraembryonic region of the parthenotes than in that of normally fertilized embryos.View full abstractDownload PDF (403K) -
Motoe KATOH, Noriho TANAKA, Shigeo IWAHARA1981 Volume 56 Issue 4 Pages 357-363
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSEvidence that MC-induced dominant lethal mutations in early spermatids are attributable to chromosome aberrations was obtained through cytogenetic analysis of first-cleavage metaphases. Male mice were intravenously injected with 5mg/kg of mitomycin C (MC). These males were serially mated with females during 6 weeks after treatment. Chromosome slides were prepared from eggs collected from the ampulla. The maximum frequencies of chromosome aberrations in male pronuclei in the eggs were obtained in early spermatid stages. A close correlation between the frequency of eggs with chromosome aberrations and that of dominant lethal mutations at the same dose was observed.View full abstractDownload PDF (476K) -
Yoshitaka OBARA, Takeshi MIYAI1981 Volume 56 Issue 4 Pages 365-371
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSChromosomes of the Ryukyu house shrew Suncus murinus riukiuanus, were studied in 4 laboratory-bred specimens. While the autosomal constitution was almost identical with that of the Ryukyu house shrew so far reported, the sex chromosomes remarkably differed in size and morphology from those of reported cases. Three different types of the X chromosomes were distinguished: (1) a metacentric one, (2) a submetacentric one smaller than the first type, and (3) a metacentric one which was equal in size to that of the second type. The Y was represented by a medium-sized metacentric element. C-banding revealed that the amount and distribution of constitutive hetero-chromatin (C-heterochromatin) in the sex chromosomes were different from those hitherto reported. The possible participation of C-heterochromatin in the sex chromosome variation in Suncus murinus is discussed.View full abstractDownload PDF (783K) -
I. The amount of heterozygosityTsuneyuki YAMAZAKI1981 Volume 56 Issue 4 Pages 373-383
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSThe amount of genetic variability expected in natural populations is different for diploid and haploid organisms under most selection models: diploid organisms are expected to be more polymorphic. I examined several natural Japanese populations of haploid moss, Conocephalum conicum by starch gel electrophoresis. Seven enzyme loci out of 11 examined turned out to be polymorphic. The average heterozygosity at the 11 loci was 0.167. This value is almost identical to those obtained in diploid organisms of various sources. Moreover, abundant genic variability was found within a local population, indicating the prevalence of sexual reproduction in natural populations of this species. The equality of genic variability between diploid and haploid organisms is most easily explained by the selective neutrality of allozyme polymorphisms, though other possibilities are not excluded from the present data alone.View full abstractDownload PDF (407K) -
IV. Genetic analyses in hexaploid wheatKozo NISHIKAWA, Yoshihiko FURUTA, Yasuhiko NINA, Toshihiko YAMADA1981 Volume 56 Issue 4 Pages 385-395
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSConventional gene analysis, monosomic analysis and telocentric method of mapping were carried out with respect to α-amylase zymogram variations of germinating seed of hexaploid wheat. The gene for Band 1(Amy 6D1) was located on 6DL with the recombination value of 11.9±2.8(%) from the centromere. Its minor allele, Amy 6D1M and null allele, Amy 6D1° were also detected in spelta duhamelianum, and Prelude, respectively. The locus for Band 2 was polymorphic, there being two alleles, Amy 6A1 and Amy 6A1M, for Band 2 major and minor, respectively. The gene for Band 3, Amy 6B1, was on 6BL with the recombination value of 19.4±3.8(%) from the centromere. On this locus, there were two other alleles, Amy 6B14′, and Amy 6B1° for Band 4′ and absence of both Band 3 and 4′, respectively. On the same chromosome was another α-amylase locus having two alleles, Amy 6B2 for Band 10 and its null allele, Amy 6B2°, distant from Amy 6B1 by the recombination value of 20.6±2.2(%). There were two alleles, Amy 4 and Amy 4M for Band 4 major and minor. Amy 7B2 for Band 14 was detected on 7B in addition to Amy 7B1 for Band 15.View full abstractDownload PDF (442K) -
Masaaki IHARA, Toru ENDO1981 Volume 56 Issue 4 Pages 397-407
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSEndosperm alcohol dehydrogenase (ADH) was investigated electrophoretically in T. kamtschaticum Pall. (2n=10; K1K1), T. tschonoskii Maxim. (2n=20; K2K2TT), T. smallii Maxim. (2n=20; SSUU) and their F1 hybrids. Main electrophoretic phenotypes so far detected are composed of fast, slow and intermediately moving bands. We denote them for convenience as F, S and H bands, respectively. T, kamtschaticum shows only F band; T, tschonoskii has two visible and one concealed S bands, viz., the main slowest band (S1), a hybrid band (S2) and slightly faster but concealed band (S3); T. smallii reveals all three main bands or FS pattern. All the F1 progeny of interspecific crosses exhibit the FS pattern. We assign the following alleles for respective ADH isozymes of each entity: AdhF′(K) in T. kamtschaticum, Adhs1(T) and AdhS2(T) in T. tschonoskii and AdhF′(S) and AdhS(S) in T. smallii. In vitro dissociation-recombination experiment demonstrates that these isozymes are dimers. These isozymes exhibit substrate specificity for alcohols with -CH2OH radical remarkably, viz., the highest activity for ethanol and n-propyl alcohol but inert for isopropyl alcohol and so forth.View full abstractDownload PDF (582K) -
Sadao ICHIKAWA, Catarina S. TAKAHASHI, Chizu NAGASHIMA-ISHII1981 Volume 56 Issue 4 Pages 409-423
Published: 1981
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSTwo triploid clones (KU 7 and KU 9) of Tradescantia heterozygous for flower color were exposed to 1 to 42.3R of gamma rays or the scattering radiation in the gamma field of the Institute of Radiation . Breeding. Occurrence of somatic pink mutations in the stamen hairs was investigated 10 to 16 (or 14) days after irradiation. The mutation frequency was found to increase linearly with increasing gamma-ray exposure in the both clones, and the frequencies of 0.437 and 0.468 pink mutant events per 103 hairs per R were determined for KU 7 and KU 9, respectively. When the data collected in the present study were analyzed together with those obtained in earlier experiments in the gamma field, linear relationships of the somatic mutation frequency with gamma-ray (2.1 to 201.6R) and scattering radiation (0.72 to 57.6R) exposures were confirmed. Scattering radiation was found to have a genetical efficiency more than two times higher than that of gamma rays. Variation of spontaneous mutation frequency observed in the present study and in earlier studies was inversely correlated to temperature variation.View full abstractDownload PDF (641K)
- |<
- <
- 1
- >
- >|