摘要:

For the first time a case of X-trisomy (XXX-gonosome aberration) in a Fleckvieh-heifer is reported. Cytogenetic examination of leukocytes and tissue cultures from the skin of this animal gave in 100% of the examined cells the karyotype 2N = 61, XXX. Except for a pronounced kyphosis of the lumbar column, there were no clinical symptoms. Sex organs and sexual function showed nothing peculiar. The teratogram from the father of the XXX-heifer showed genetical connections in the etiology of kyphosis. It seems also that in the family line an inherent genetical disposition to meiotic disturbances, in the sense of non-disjunction, exist because recently a case of an XXY-gonosome abnormality with bilateral testicle hypoplasia (bovine hypogonadism) was registered in the second generation of the father’s bree

ISSN:1424-8581    

DOI:10.1159/000130110

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Somatic interphase nuclei of different tissues of heterogametic females of various species of snakes with a differentiated W chromosome possess a distinct, darkly stained chromocenter comparable to the characteristic mammalian sex chromatin. The absence of such a prominent body in similar tissues of homogametic males, the allocycly in the DNA replication pattern exhibited by the W, and the positive correlation between the size of the chromocenter and the size of the W in different species are the evidence from which it is concluded that the sex-chromatin body of the interphase nuclei in snakes is formed by the W chromosome of the heterogametic females. The lack of incorporation of 3H-uridine by the chromocenter indicates its inactivity. In order to distinguish this heteropycnotic body from the sex chromatin of the homogametic sex in mammals, it is suggested that it be termed “W chromatin

ISSN:1424-8581    

DOI:10.1159/000130111

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

A computer system to both measure and classify human chromosomes with good accuracy compared to manual methods is described. Using a 35-mm photomicrographic negative, the system, while measuring the chromosomes automatically, requires a human operator’s interaction for about 15% of the chromosomes. Results for an initial 45 spreads are given. Using the interactively measured arm lengths and arm areas, the system classified over 99% of the chromosomes correctly into 10 classes without any assistance; two chromosomes, or 0.1% of the initial sample, were misclassified (from group D to E). For the remaining 1%, interaction after classification was requested by the computer, and, with the information available to the operator, a correct classification can be made in these cases by him. The system uses a computer-controlled flying spot scanner connected to a medium-size general purpose computer, an IBM 360 Series, Model 30, and takes 25 min per spread. An annual capacity of 7500 analyzed spreads will be available in 1971 after installation of an RCA Spectra 70/46, operating under a multi-programmed system, in October 1970. Applications for the system may depend on cytogeneticists exploiting its advantages and avoiding the drawbacks describe

ISSN:1424-8581    

DOI:10.1159/000130112

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Whole-mount electron microscopy of metaphase mouse L-cells showed that in many cases the region of the centromere was located at one extreme end of the chromosome with no evidence for short arms of any significant size. In such telocentric chromosomes there was only a single area of chromatid association. By contrast, the region of the centromere in mouse metacentric chromosomes was much longer. When well dispersed, it was seen to consist of two distinct areas of chromatid association, each of which was comparable in length to that of the telocentric chromosomes. In the region between these two areas there was a decrease in the density of the chromatin fibers. A similar quadripartite morphology was seen in human, Chinese hamster, and sheep metacentric chromosomes. These findings are most simply interpreted by the proposal that the quadripartite centromere of the metacentric chromosomes has resulted from the fusion of two telocentric chromosomes with bipartite centromeres.

ISSN:1424-8581    

DOI:10.1159/000130113

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Half-chromatids have often been observed by light microscopy. Similar structures were looked for by electron microscopy of whole-mount preparations of mitotic cells from seven different species of mammals and birds. Of over 3000 plates examined showing all degrees of dispersion of the chromatin fibers, there was no evidence that the chromatid was made up of any subunits larger than the chromatin fiber. In an occasional specimen treated with sodium dodecyl sulfate the chromatid showed dense peripheral regions similar to the half-chromatids seen by light microscopy following trypsin treatment. However, the resolution provided by the electron microscope demonstrated that this was not a true subdivision of the chromatid. It is suggested that the observation of half-chromatids is valid but the conclusion that they represent independent portions of the chromatid, or that they provide any evidence as to the strandedness of chromosomes, is not.

ISSN:1424-8581    

DOI:10.1159/000130114

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Meiotic and histological studies have been carried out on testicular biopsies from an azoospermic human male who exhibited normal secondary sex characteristics. A failure in the formation of chiasmata during the first meiotic prophase resulted in a breakdown of the subsequent meiotic and spermatogenic processes. The few spermatozoa formed exhibited a range of DNA contents consistent with a random orientation and movement of the meiotic chromosomes. Radiation studies carried out on peripheral lymphocytes demonstrated that the patient had a reduced facility for chromosomal DNA repair. It is suggested that this defect gives an explanation for the failure of chiasma formation since chiasma formation probably involves a breakage, crossingover and repair of chromosomal DNA during the first meiotic prophase.

ISSN:1424-8581    

DOI:10.1159/000130115

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

A cell line from a female Microtus agrestis has been established in vitro, with most cells showing the normal female complement with two entire X chromosomes. Cloning of this line yielded stable cell strains, some of which showed deletions of the X chromosomes. Karyotypically, the deletions include (1) loss of the long arm of one X chromosome, (2) loss of one entire X chromosome, and (3) loss of one entire X chromosome together with loss of the long arm of the other X chromosome. In the last case, only the “functional” portion of the presumably active X chromosome remained. Radioautography has confirmed the actual loss of both constitutive and facultative heterochromatin from the X chromosomes in these clones. In addition, the parent cell line yielded a clone tolerant to 5-bromodeoxyuridine (BUdR) at 5 µg/ml. This cell strain retains thymidine kinase activity, however, as evidenced by uptake of thymidine, and by incorporation of BUdR into the

ISSN:1424-8581    

DOI:10.1159/000130116

出版商:S. Karger AG    

年代:1970

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130117

出版商:S. Karger AG    

年代:1970

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130118

出版商:S. Karger AG    

年代:1970

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130119

出版商:S. Karger AG    

年代:1970

数据来源: Karger