All issues
Volume 27, Issue 2
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Ohtsura NIWA1987 Volume 27 Issue 2 Pages 53-59
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSTranscription of polyoma, SV40 and Moloney leukemia virus genomes is suppressed in undifferentiated teratocarcinoma cells. This suppression is due to a celluar factor (or factors) present in the stem cells of the early developmental stage of embryogenesis. Inhibition of transcription involves sequence specific interaction of the factor to viral enhancers. The repressor-like factor thus revealed from the study of virus infection of undifferentiated stem cells, seems to play an important role in the maintenance of the undifferentiated state of cells. A variety of host cellular genes may be regulated by this factor.View full abstractDownload PDF (1491K) -
Hatsuho UEDAIRA, Shun-ichi KIDOKORO, Akiyoshi WADA1987 Volume 27 Issue 2 Pages 60-66
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSRecent developments of differential adiabatic scanning microcalorimetry have been permitted the precise measurements of the slight changes in heat capacity of the dilute protein solution which is caused by the transition of the higher order protein structure. As the most important feature of the calorimetry is the direct observation of thermodynamic functions, it is an effective measurement for the thermal stability and fluctuation of protein molecule. In this article, a brief review on the basic principle of the calorimetry and new statistical thermodynamic methods for the calorimetry data analysis, by which thermodynamic characteristics of globular proteins have been well recognized, is presented. Cold denaturation and multistate transition of protein molecule are mentioned.View full abstractDownload PDF (1474K) -
Satoru FUJIME1987 Volume 27 Issue 2 Pages 67-70
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSA method of dynamic light scattering is discussed with special emphasis on rotational and bending motions of linear macromolecules in suspension. Recent results on tobacco mosaic virus and bacteriophage fd are briefly reviewed as examples studied by the method.View full abstractDownload PDF (854K) -
Masashi SUZUKI1987 Volume 27 Issue 2 Pages 71-74
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSIn this review I have described our current view about the mode of packaging of DNA in house cricket (Gryllus bimaculatus) spermatids. DNA is oriented as the helix axis of it is parallel to the long axis of the nucleus. About two hundred and forty DNA fibers are bundled into one unit, 300Å fiber. More than two hundred 300Å fibers are packed also parallel in one nucleus. In mature cells histones have been replaced by another kind of protein (Mr=17, 000), which is not so basic as they. This mode of packaging of DNA cannot be the nucleosome structure. The packaging ratio (the ratio of the volume of DNA to that of the nucleus) of this system is about 1 and shows effectiveness much higher than that of solenoid structure in the nucleosome theory but similar to that of the packaging of DNA in λ phage head.View full abstractDownload PDF (1431K) -
Teruko Taketo-Hosotani1987 Volume 27 Issue 2 Pages 75-83
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe sex of an individual is determined at fertilization by the combination of sex chromosomes, e.g., XX or XY in mammals. Morphological sex differences become evident during the organization of gonadal primordia into ovaries or testes. Consequently, fetal testes produce hormones which are responsible for the development of the male phenotype. The absence of male hormones results in the development of the females phenotype. It has been proposed that a male dominant, histocompatibility-Y (H-Y) antigen
determines testicular differentiation, based on the finding that individuals with testest are H-Y antigen positive regardless of their sex karyotype. Recently, this hypothesis has been challenged bý the finding of several exceptions, e.g., development of ovaries in the presence of H-Y antigen, and testes in its absence.
A testis-determining gene (Tdy or TDF) has been thought to occur on the Y chromosome. Over 100 Y-specific DNA fragments have been examined with only one possible candidate for the Tdy gene. In addition to the Tdy gene, at least two autosomal genes (tda-1 and Tas) appear to be involved in testis determination. It has been suggested that gonadal sex determination may also be influenced by environmental factors.
Fetal rat and mouse ovaries develop testicular structures (ovotestes) after transplantation into various sites of adult host animals. This finding suggests that XX gonadal primordial cells can differentiate into testicular cells. Electron microscopic examinations have revealed that testicular structures of mouse ovotestes are comparable to those of the genetic male. Furthermore, it has been shown that ovotestes produce hormones and glycoproteins characteristic of normal neontal testes. These results provide strong evidence for sex reversal by transplantation. The study of the factors involved in the induction of ovotestis development should aid better understanding of the mechanism of gonadal sex determination.View full abstractDownload PDF (1029K) -
[in Japanese], [in Japanese]1987 Volume 27 Issue 2 Pages 84-86
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSDownload PDF (138K) -
[in Japanese], [in Japanese], [in Japanese]1987 Volume 27 Issue 2 Pages 87-90
Published: March 25, 1987
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSDownload PDF (817K)
- |<
- <
- 1
- >
- >|