All issues
Successor
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 4
Displaying 1-9 of 9 articles from this issue
- |<
- <
- 1
- >
- >|
-
GENTARO ITAGAKI1970 Volume 45 Issue 4 Pages 239-254
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe change of each spermatogenetic cell population in mice from 6 hours to 14 weeks after irradiation of 1000R was investigated quantitatively and histologically, directing particular attention to the difference in X-ray sensitivity of spermatogonia.
The decrease in spermatogenetic cell populations after irradiation occurs according to the order of their developmental stages showing the higher sensitivity of spermatogonia to X-rays: spermatogonia begin to decrease with a high incidence of necrosis at 12 hours after irradiation and show a remarkable loss at the 3rd day. At the 12th day spermatocytes have disappeared completely. The depletion of spermatids and spermatozoa occurs respectively at the 3rd and the 4th week showing their resistance to X-rays of high dosages.
The present studies, in comparing the sensitivity of spermatogonia, indicate that intermediate and type B cells are more sensitive to radiation than type A cells. Further, it seems to support the view that a few spermatogonia of type A showing heterogeneous sensitivity survive after irradiation and repopulate new spermatogenetic cell elements.
Although a large number of spermatogonia degenerate immediately after irradiation showing necrosis, some spermatocytes become abnormal spermatids, as revealed by signet-ring cells, multinucleated cells and unusual size of nuclei, suggesting the formation of abnormal spermatozoa.
An occurrence of Sertoli cells and interstitial cells in considerable numbers in severely damaged testes, suggested their high resistance to X-rays. Their apparent increase seems to be a relative increase due to the shrinkage of seminiferous tubules accompanying with the depletion of the tubular constituents.
The rate of decrease of the tubule-diameter after irradiation depends on the radiation dose. From this fact, the tubule-diameter curve may play a role of comparing radiation effects.View full abstractDownload PDF (3651K) -
MASAHIDE KURITA, YUZO KUROKI1970 Volume 45 Issue 4 Pages 255-260
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSA cytological study was made mainly on the Y-chromosomes in connection with chromocenters in Rumex acetosa L. At mid-prophase in somatic cells, the Y1-chromosome was found to consist of two different segments besides the centromere: one is derived from the chromocenter, another is euchromatic, but different in condensation from the euchromatic part of the X-chromosome and also of the autosomes. The Y2 has sometimes a dim or hyaline small segment at the distal end of the long arm besides those two segments as found in the Y1. Furthermore, at mid-prophase the Y-chromosomes are, on the whole, more darkly stained than any other chromosome. Then, the Y's can be said to be entirely heteropycnotic at this stage, in spite of showing a partial heteropycnosis at early prophase and interphase where the distal part of the short arm revealed itself as a chromocenter.View full abstractDownload PDF (1250K) -
AKIRA UCHIDA, KOHTA SUDA1970 Volume 45 Issue 4 Pages 261-268
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSA temperature sensitive mutant of Saccharomyces cerevisiae was isolated with partially defective respiratory activity at high temperature. The respiratory activity of the mutant was reduced to approximately 1/4 of the parental strain after grown at 30°C, and it could be improved to be normal after grown at 20°C. Spectrophotometric analysis showed that the mutant could synthesize only small amounts of cytochromes b and a at 30°C. Genetic analyses revealed that two gene mutations for the respiratory activity of the mutant were involved.View full abstractDownload PDF (715K) -
ISOJI MIWA, KOICHI HIWATASHI1970 Volume 45 Issue 4 Pages 269-275
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe length of immaturity in Paramecium caudatum was investigated counting the fissions exactly in daily isolation culture in depression slides and the following results were confirmed.
(1) The length of immaturity depends upon the times of fissions rather than days when temperature limits the fission rate.
(2) Mitomycin C shortens the length of immaturity about 10 fissions.
(3) The maturity in the clones determined to mating type V appears about 10 fissions earlier than those determined to mating type VI.View full abstractDownload PDF (753K) -
YASUO OHTA1970 Volume 45 Issue 4 Pages 277-283
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSInoculation experiments with various viruses were performed with Capsicum annuum L. Plants were used with known cytoplasmic and genotypic characters concerning pollen fertility (Table 1). The results with a set of three F1 hybrids, having identical genotypes for pollen fertility and identical genetic backgrounds, have revealed that it is the cytoplasm which is primarily responsible for the reduction of pollen fertility after infection by specific viruses.
Progeny tests have provided more evidence (Tables 2 and 3) indicating that pollen fertility in plants having (S) cytoplasm and Rfrf genotype, and should be pollen fertile, was reduced following infection with specific viruses.
It is concluded that a certain interaction between specific viruses and a particular cytoplasm (S) is responsible for the reduced pollen fertility. In other words, the specific cytoplasm (S) modifies the action of Rf-gene by interacting with specific viruses.
Since it is evident that a cytoplasmic entity reacts in this way with specific viruses, its nature and origin were discussed, and the following speculation was proposed. A cytoplasmic entity for male sterility in Capsicum could have originated from an exogeneous virus in the course of evolution followed by the loss of infectivity. Then it may be supposed to have arrived at a state of a kind of plasmon or plasmid of RNA nature.View full abstractDownload PDF (654K) -
KATSUMI ISONO1970 Volume 45 Issue 4 Pages 285-291
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDNA was extracted from Bacillus stearothermophilus, strain BS-1, a derivative of ATCC 12980, by shaking cells with a mixture of chloroform and iso-amylalcohol in the presence of sodium deoxycholate and partially purified by the treatment with RNase A. This DNA preparation was shown to induce genetic transformation of the amylase-deficient mutants which were made competent by culturing cells in a semi-defined medium devised by the author specifically for this bacterial species.View full abstractDownload PDF (721K) -
KAZUYOSHI KIRITANI, NORIKO INUZUKA1970 Volume 45 Issue 4 Pages 293-304
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSSeven isoleucine, valine and leucine requiring mutants were isolated after treatment of Salmonella typhimurium LT-2 with nitrosoguanidine. Growth of six strains is stimulated by pantothenate. The mutant strains are classified into two groups. Mutants of group 1 have deficiency in activity of the α, β-dihydroxyacid dehydratase, and deficiency or alteration in the branched-chain-amino-acid aminotransferase. Group 1 is divided into polarity mutants, KA2, KA12 and KA13, and nonpolar mutants, KA1 and KA21, as judged by activities of the threonine dehydratase and the α, β-dihydroxyacid dehydratase. Activity of the reductoisomerase in the KA21 strain is also low. Mutants of group 2, KA6 and KA19, are deficient in activity of the α, β-dihydroxyacid dehydratase and show low valine permeability. The branched-chain-amino-acid aminoransferase of KA19 is also altered. The mutational site in each of the mutants is located in the ilv cluster. The evidence indicates that limited synthesis of α-ketoisovalerate is responsible for the multiple requirements of bacteria.View full abstractDownload PDF (1048K) -
T. S. DHILLON1970 Volume 45 Issue 4 Pages 305-312
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSAutotetraploidy was induced in Phlox drummondii by treatment of shoot apices of seedlings with 0.5% emulsion of colchicine in lanolin. Autotetraploid plants were found to show gigantism, both at the cellular level as well as the organ level. Pollen mother cells of autotetraploid plants showed predominantly bivalents and quadrivalents. Although pollen abortion in autotetraploids was only slight, seed set of such plants was markedly reduced. Possible mechanisms for the reduced seed set are discussed.View full abstractDownload PDF (1151K) -
YUH H. NAKANISHI, SHUNSAKU UTSUMI, I-MIN LIU1970 Volume 45 Issue 4 Pages 313-315
Published: 1970
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSDownload PDF (1015K)
- |<
- <
- 1
- >
- >|