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Volume 45 (1970)
- Issue 6 Pages 425-
- Issue 5 Pages 319-
- Issue 4 Pages 239-
- Issue 3 Pages 173-
- Issue 2 Pages 87-
- Issue 1 Pages 1-
Volume 45, Issue 2
Displaying 1-8 of 8 articles from this issue
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KENDO TSUNO1970 Volume 45 Issue 2 Pages 87-100
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS(1) Many haploid sets of second and third chromosomes were extracted from different male flies of D. melanogaster collected from a natural population in Kofu city and a cage population which was initiated with flies collected from the same natural population and has been kept for two years under a constant temperature of 25°C.
Viabilities of homozygotes for these autosomes both together (double homozygote) and also viabilities of homozygotes for each autosome separately (single homozygote) were estimated by Cy L/Pm; Ubx/Sb method.
(2) Frequencies of lethal second chromosomes in both populations did not significantly differ with each other. But those of lethal third chromosomes were quite different. The frequency of lethal third chromosomes in the natural population was significantly higher than of lethal second chromosomes. The mean viability of homozygotes for quasinormal third chromosomes in the natural population was slightly lower than that for quasinormal second chromosomes.
(3) Combinations between the two major autosomes, which were lethal, semilethal +subvital, and normal, were almost at random, but one compensatory combination was detected. And also two synthetic semilethals were found among the sets of two major autosomes extracted from the cage population.
(4) Interaction between the two major autosomes in homozygous state was examined as to viabilities of double homozygotes and some synergistic effects of deleterious genes of both autosomes were recognized in most cases. Within higher viability range, especially, a remarkable positive synergistic interaction was observed.
The regression coefficients of observed viabilities on expected ones for the two autosomes extracted from both cage and natural populations were 0.80 and 0.87, respectively. The synergistic effects on the viability of double quasinormal (subvital+normal) homozygotes were discussed.View full abstractDownload PDF (1379K) -
KAZUHIRO IWO, SOHEI KONDO1970 Volume 45 Issue 2 Pages 101-119
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSNon-filamentous (Fil-) derivatives were isolated from E. coli strain Bs-1 and its lysogenized strain Bs-1(80). These Fil- strains were 70 times more UV resistant, 1.5 times more X-ray resistant and had lower growth rate than Bs-1 and Bs-1(80). Transfer of episome F'13 resulted in complete (or partial) reversion of their characters to those of strain Bs-1 (or Bs-1(80)). Entry of episome F'13 altered the Fil- UVr phenotype of gene lon+ in wild-type K12 strains to Fil+ but UVr phenotype, and the Fil+ UVs phenotype of gene lon in filamentous K12 mutants to Fil+ but UVr phenotype, whereas it did not affect the Fil+ UVs phenotype of gene uvs in strains B and Bs-1. The following conclusions are reached. 1) Fil+ character is not necessarily correlated with UVs character. 2) Gene uvs is not identical (but probably allelic) to lon and dominant to lon+. 3) Gene lon+ is dominant to lon for radiation resistance but not so for Fil- character. 4) Fil-, UVr and slow-growing characters are induced in strain Bs-1 through genetic suppression of function of uvs by single or multiple suppressor genes. 5) Conclusion 4) may be related to the mystery why the extremely UVs strain Bs-1 was discovered by Hill (1958) in surviving colonies of heavily UV irradiated culture of strain B. 6) The newly found suppressor gene in Fil- derivatives of strain Bs-1 seems to have ability to give higher UV resistance than similar suppressor gene in B/r type strains.View full abstractDownload PDF (3373K) -
MASAHIRO ITOH, MOTOMICHI SASAKI, SAJIRO MAKINO1970 Volume 45 Issue 2 Pages 121-128
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSChromosome-number distributions in 5 species of Japanese snakes are presented in Table 1.
Elaphe climacophola, E. quadrivirgata and Natrix vibakari showed the same diploid number, 36, with an identical karyotype showing 8 pairs of macrochromosomes and 20 microchromosomes. Agkistrodon halys showed the same chromosome number, but had a slightly different karyotype explicable by pericentric inversion of the no. 6 macrochromosomes. Rhabdophis tigrinus had 40 chromosomes consisting of 8 pairs of macrochromosomes and 24 microchromosomes. Its karyotype seems to be explained by reciprocal translocation and centromeric fusion-fission mechanism in the four species.
Sexual dimorphism of the chromosomes is represented by the no. 4 (or 5) chromosomes with the ZZ/ZW mechanism, showing female heterogamety. The Z chromosome is metacentric, while the W subtelocentric. The morphological difference between them is interpreted as a result of pericentric inversion.View full abstractDownload PDF (1621K) -
YOSHIHIKO FURUTA, MASATAKE TANAKA1970 Volume 45 Issue 2 Pages 129-145
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSIn respect to the origin of the tetraploid Aegilops species, Zohary and Feldman (1962) postulated a polyphyletic origin by introgression. However, Kihara (1954) did not consider introgression as a mechanism for producing a new genome form.
In order to examine whether or not introgression occurs between tetraploid species belonging to the Polyeides section of Aegilops, cytological and morphological analyses were carried out on hybrid progenies of three ross-combinations; Ae. triaristata (CuMt), Ae. variabilis (CuSv), and Ae. biuncialis (CuMb)×Ae. columnaris (CuMc), where the Cu genome was the common buffer genome and Mt, Sv and Mb were known to form 5, 3.5 and 2 bivalents, respectively, with the Mc genome.
In the most closely related combination, Ae. triaristata×Ae. columnaris, introgression was confirmed cytologically and morphologically. Also, in the second, intermediately related combination, Ae. variabilis×Ae. columnaris, only introgression between two homologous chromosomes or chromosome segment(s) was observed. However, in the third distinctly related combination, Ae. biuncialis×Ae. columnaris, no introgression took place.
These facts suggest that introgression occurs in connection with the relationship between species and that it is one of the factors responsible for the origin of new genomes and variations in the Aegilops tetraploid species.View full abstractDownload PDF (1415K) -
TOMOTAKA SHINODA1970 Volume 45 Issue 2 Pages 147-152
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSPolymorphism of red cell adenosine deaminase has been investigated in 931 unrelated samples taken from adults collected in two different areas, Tokyo and Misima, Sizuoka Prefecture. Altogether 25 familial samples including 30 children were also tested for the enzyme types.
There was no difference in the frequencies of genes ADA1 and ADA2 either between the sexes or between the two areas, and their respective frequencies for the pooled data were 0.969 and 0.031. The familial segregation and the phenotypic distribution agreed well with the genetic hypothesis. There was no association in the distribution of these phenotypes with the ABO blood groups.View full abstractDownload PDF (684K) -
SHINJI MATSUMOTO, YOSHIKO KAGAMI-ISHI1970 Volume 45 Issue 2 Pages 153-160
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSLife times of radiosensitive strains of Escherichia coli and Saccharomyces cerevisiae have been obtained with logarithmic and stationary phase cells at various temperatures. The results of temperature dependence of mortality rate were well described by the first order chemical reaction formula (Arrhenius equation). In the case of E. coli JC 1569 b rec- and its original rec+ strains, the difference in survival curves between them appeared only in logarithmic phase cells and was described as a difference in energy independent term in the Arrhenius equation. These results have suggested that these rec+ and rec- strains have a recovery mechanism but the rec- strain could not repair the damage enough to survive during exponential growth and/or tolerate the injury for a subsequent DNA replication and growth.View full abstractDownload PDF (718K) -
YOSHIO OJIMA, SHINYA HITOTSUMACHI, MAKOTO HAYASHI1970 Volume 45 Issue 2 Pages 161-162
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (436K) -
S. RAJASEKARAN1970 Volume 45 Issue 2 Pages 163-166
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (1435K)
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