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Volume 63 (1988)
- Issue 6 Pages 501-
- Issue 5 Pages 413-
- Issue 4 Pages 283-
- Issue 3 Pages 217-
- Issue 2 Pages 113-
- Issue 1 Pages 1-
Volume 63, Issue 3
Displaying 1-7 of 7 articles from this issue
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James F. Crow1988 Volume 63 Issue 3 Pages 217-218
Published: 1988
Released on J-STAGE: July 25, 2006
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Takayoshi USDA, Ryozo SATO, Jindo KOBAYASHI1988 Volume 63 Issue 3 Pages 219-226
Published: 1988
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSSilver-banded karyotypes of the rainbow trout Salmo gairdneri, the brook trout Salvelinus fontinalis, and their hybrids were described. Diploid-type and triploid-type hybrids were obtained. Triploid-type hybrids had two maternal genomes of the rainbow trout and one paternal genome of the brook trout. The rainbow trout had one pair of M or SM with Ag-NORs near the satellite. In the brook trout, Ag-NORs were observed in four pairs of chromosomes, but each cell had different number of chromosomes with Ag-NORs. In all observed cells of triploid-type hybrids, Ag-NORs originated from the brook trout were not recognized, whereas those from the rainbow trout were found.View full abstractDownload PDF (1106K) -
I. Microevolution of male recombination determinants in experimental populationsSetsuko YAMAOKA, Osamu YAMAGUCHI1988 Volume 63 Issue 3 Pages 227-236
Published: 1988
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSFive natural populations of D. melanogaster in Japan were surveyed for male recombination frequency in terms of the quantities of the mean and variance after crossing with cn bw females. The experimental condition enabled P-M system hybrid dysgenesis to take place. The means were not so different from one another, but there was a vast variation in the variances between them. Using one of these populations, two additional experimental populations were started, and the male recombination frequencies were monitored for 30 generations. Both the means and variances decreased in value at 25°C. The regression line was Y=-0.000030X+0.001706 on generation for the mean values, and was Y=-0.000098X+0.005068 for the standard deviations in the cage population. There was no correlation between the means or the standard deviations and the copy numbers of the members of P element family as a whole. The experimental results indicate that the complete P transposable elements still retained in population were decreased in frequency and replaced by its degenerative nonautonomous forms.View full abstractDownload PDF (447K) -
I. Mutations near the anticodon cause mischargingFumiaki YAMAO, Hachiro INOKUCHI, Haruo OZEKI1988 Volume 63 Issue 3 Pages 237-249
Published: 1988
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSIn order to select the mischarging mutants of Su+2 glutamine tRNA, auxotrophic amber mutants of E. coli K12 which cannot be suppressed particularly by Su+2 were screened. By utilizing these mutants, cysam235 and metam3, several tens of mischarging mutants of Su+2 were isolated, as those conferring altered suppression patterns for a set of tester amber mutants of bacteria and phages. Nucleotide sequence analysis revealed that the mutation sites were found to be exclusively at Ψ37 residue located at the 3′-end of anticodon loop, changing it to either A37 or C37. These mutants were obtained as those suppressing cysam235, and not metam3. From these, secondary mutants were selected. In these mutants suppression patterns were further altered by the additional base substitutions, capable of suppressing metam3. Such mutants were obtained exclusively from A37 and not from C37 mutant tRNA. Additional mutations to A37 were found to be either A29 or C38, which are located at the lowermost two base pairs in anticodon stem. The mischarging sites in Su+2 glutamine tRNA locate in the newly detected region of tRNA, differing from the previous case of Su+3 tyrosine or Su+7 tryptophan tRNAs. Implication of this finding is discussed on L-shaped tRNA molecule in relation to aminoacyl-tRNA synthetase recognition. Suppression patterns given by the double-mutants, A37A29 and A37C38, were consistent with the observation that the mutant tRNAs interact with tryptophanyl-tRNA synthetase.View full abstractDownload PDF (931K) -
II. Amino acid specificities of the mutant tRNAsFumiaki YAMAO, Hachiro INOKUCHI, Jennifer NORMANLY, John ABELSON, Haru ...1988 Volume 63 Issue 3 Pages 251-258
Published: 1988
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSAmong the mischarging mutants isolated from strains with Su+2 glutamine tRNA, two double-mutants, A37A29 and A37C38, have been suggested to insert tryptophan at the UAG amber mutation site as determined by the suppression patterns of a set of tester mutants of bacteria and phages (Yamao et al., 1988). In this paper, we screened temperature sensitive mutants of E. coli in which the mischarging suppression was abolished even at the permissive temperature. Four such mutants were obtained and they were identified as the mutants of a structural gene for tryptophanyl-tRNA synthetase (trpS). Authentic trpS mutations, such as trpS5 or trpS18, also restricted the mischarging suppression. These results strongly support the previous prediction that the mutant tRNAs of Su+2, A37A29 and A37C38, are capable of interacting with tryptophanyl-tRNA synthetase and being misaminoacylated with tryptophan in vivo. However, in an assay to determine the specificity of the mutant glutamin tRNAs, we detected predominantly glutamine, but not any other amino acid, being inserted at an amber codon in vivo to any significant degree. We conclude that the mutant tRNAs still accept mostly glutamine, but can accept tryptophan in an extent for mischarging suppression. Since the amber suppressors of Su+7 tryptophan tRNA and the mischarging mutants of Su+3 tyrosine tRNA are charged with glutamine, structural similarity among the tRNAs for glutamine, tryptophan and tyrosine is discussed.View full abstractDownload PDF (399K) -
Yasuo UKAI1988 Volume 63 Issue 3 Pages 259-265
Published: 1988
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSStatistical tests on the distribution of the number of chiasmata per chromosome, collected from literatures, showed that they can be approximated by binomial distributions with one obligatory chiasma, i.e., B(N-1, p). N is proportional to the average number of chiasmata, while p is nearly constant for the species tested.View full abstractDownload PDF (216K) -
Kenji TANIGUCHI, Ryuso TANAKA, Naoto ASHITANI, Hideki MIYAGAWA1988 Volume 63 Issue 3 Pages 267-272
Published: 1988
Released on J-STAGE: July 25, 2006
JOURNAL FREE ACCESSShoot primordia of annual Haplopappus gracilis (2n=4) propagating vegetatively in vitro provided a new possibility for freeze preservation. The method of freeze preservation was as follows. Subcultured shoot primordia were precultured in an MS medium supplemented with 5% DMSO for 3 days. They were cooled at a velocity of -0.5°C/min down to -40°C in a programming freezer, and then stored in liquid nitrogen immediately. The frozen shoot primordia were thawed quickly in a water bath at 37°C, and recultured. The recovered shoot primordia were highly stable in the chromosome number and karyotype, which were the same as in the original plant and in the control shoot primordia without the freezing treatment. In comparison with a method using shoot tips, the above method is advantageous of being possible to store a large number of pieces of shoot primordia more easily, and also to mass-propagate plantlets clonally.View full abstractDownload PDF (463K)
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