摘要:

Potorous tridactylus and Protemnodon bicolor are marsupial species in which the sex chromosome system is XX/XY1Y2. Nearly all the long arm of the X is homologous with the Y2; the short arm of the X is unpaired in the male. During the last part of DNA synthesis in females only the short arm of one of the 2 X-chromosomes shows asynchronous synthesis of DNA. The long arm sof the X’s and homologous autosomes synthesize DNA synchronously. Some pairs of non-homologous autosomes synthesize asynchronously. The implications of this in terms of the Lyon hypothesis and the evolution of X-chromosomes are discusse

ISSN:1424-8581    

DOI:10.1159/000129857

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

An extra centric chromosome fragment was found in the karyotype of an oligospermic male and his apparently normal mother. Both karyotypes were otherwise normal and the origin of the fragment could not be determined. The possible relationship, if any, between oligospermia and the chromosomal fragment cannot be established at this time.

ISSN:1424-8581    

DOI:10.1159/000129858

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

A five-year-old mongoloid female twin was found to have the aneuploid number of 48 chromosomes. The karyotypic analysis revealed the presence of trisomy G and an additional abnormal chromosome in the smallest length range. Appropriate measurements of the chromosomes, studies of the association and satellites as well as DNA synthesis have provided certain information about the abnormal chromosome; however, its precise derivation could not be established at this time. The interest in this patient is further enhanced by the finding that she is one of twins, probably monozygotic; her twin sister is normal in all respects. Both twins have identical blood groups, Gm types and haptoglobins. Analysis of the palm and sole prints of the twins is also compatible with their monozygosity. The possible mechanism leading to the chromosomal and clinical abnormality encountered is discussed.

ISSN:1424-8581    

DOI:10.1159/000129859

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

The size of yellow and black spots in the coats of cats heterozygous for the pair of alleles controlling these colors is shown to vary in proportion to the degree of white spotting. This appears to be an example of the control of X-inactivation mosaicism of black and yellow by the autosomal locus producing the white spotting, by some mechanism as yet undescribed.

ISSN:1424-8581    

DOI:10.1159/000129860

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

Superovulation is induced in the female rodent with a priming dose of PMS followed by an ovulating dose of HCG. At proper time intervals thereafter, follicular or ductal ova can be obtained in large numbers, freed of coronal cells while in a 0.7 % sodium citrate solution and fixed in 50 % acetic acid. Freezing with dry ice and methanol permits removal of the cover slip after mild squashing and the dried preparation can then be hydrolysed with in HCL and stained with Giemsa stain. Preparations of good quality which permit examination of number and morphology of the chromosomes of ova in first or second meiotic metaphase can thus be obtained.

ISSN:1424-8581    

DOI:10.1159/000129861

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

That blood cell chimerism of dizygotic twins is accompanied by germ cell chimerism was suggested by previous demonstrations of the presence of female metaphase figures in the testis of males born twin to genetic females in cattle (Ohno et al., 1962) and the marmoset (Benirschke and Brownhill, 1963). The present findings in cattle on fetal triplets only 12 mm in crown-rump length furnishes the embryological basis for the observed phenomenon of germ cell chimerism. The liver of each triplet contained both male and female metaphase figures; cell chimerism was already established in all three. A histochemical test on alternate serial transverse sections revealed that alkaline-phosphatase-positive primordial germ cells were still in the middle of migration from the yolk sac to the developing gonadal ridges. A number of alkaline-phosphatase-positive cells were found within blood vessels, particularly within the venous sinusoids of the liver. They were interpreted to be primordial germ cells which had wandered into the blood stream.

ISSN:1424-8581    

DOI:10.1159/000129862

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

Human leukocyte cultures have been studied for the location of secondary constrictions and their frequency of occurrence. The constrictions appear most frequently in chromosomes 9 and 1, less frequently in 2, 4L, 6L, 11, 13, 16 and rarely in 3, 5L, 6S, 17, 19 and 21. In general, only one homolog bears the constriction with the exception of numbers 9 and 1. The concentration of mitotic accumulating agent appears to affect the occurrence of secondary constrictions. Cultures treated with 5-bromodeoxyuridine show many of the normally-occurring constrictions and in addition other regularly-occurring morphological markers of a similar nature.

ISSN:1424-8581    

DOI:10.1159/000129863

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

Blood leucocytes were cultured from six men before and at intervals after therapeutic irradiation of the abdomen and pelvis. There was no evidence of increased aneuploidy after exposure. By the end of radiotherapy, 32 % of metaphases showed chromosome structural aberrations (control 2 %); these declined to 8 % by the end of the follow-up (17–19 months after treatment). Cells with ‘unstable’ aberrations declined faster than ‘stable’ cells. No clones of cells were observed. Many polyploid metaphases were seen in the cultures after irradiation. There was no evidence that they were derived from circulating tumour cells or other large cells. The irradiated bone marrow was aplastic. Cells from unirradiated bone marrow had normal chromosomes. Thus, there was no evidence for the propagation of small lymphocytes (or other cells) with radiation-induced chromosome ‘markers’ in th

ISSN:1424-8581    

DOI:10.1159/000129864

出版商:S. Karger AG    

年代:1965

数据来源: Karger

摘要:

DNA replication patterns in bone marrow (somatic) and spermatogonial (gonadal) cells of the Chinese hamster were studied with autoradiographic methods. The generation time of bone marrow cells was approximately 10 h, and the G2 phase was less than 2 h. The DNA replication sequence in bone marrow cells was similar to that of somatic cells in tissue culture, i.e., the long arm of the X and the entire Y replicate in late S, but not in early S phase. The average G2 phase of the spermatogonia was approximately 6 h. Its DNA replication sequence was different from that of the somatic cells. The long arm of the X and the entire Y were not labeled in late S phase. The late labeling pattern of autosomes resembled that of the somatic cells. Since the heteropycnosis, late DNA replication, and genetic inactivation appear closely related, the DNA replication sequence of spermatogonial cells suggests that the sex chromosomes are metabolically active, at least in some stages of germ cell development.

ISSN:1424-8581    

DOI:10.1159/000129865

出版商:S. Karger AG    

年代:1965

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000129866

出版商:S. Karger AG    

年代:1965

数据来源: Karger