摘要:

Heterochromatic regions in chromosomes of man, mainly at the centromeric areas, can be demonstrated with consistency using a special staining procedure. This procedure includes treatments of cytological preparations with HCl, RNase, NaOH (denaturing DNA), and renaturing DNA in a saline citrate solution at 65°C. The heterochromatic regions can be observed after staining with Giemsa. These regions are believed to be composed of constitutive heterochromatin. Facultative heterochromatin regions, e.g., the repressed X in female cells, do not respond to this series of treatments

ISSN:1424-8581    

DOI:10.1159/000130130

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

In a female infant exhibiting cleft palate, hydrocephalus communicans, vitium cordis congenitum, and other anomalies, chromosome analysis revealed a C/D translocation. According to its replication pattern, the translocation chromosome comprised almost a whole X and the long arm of a chromosome 15. In accordance with the Lyon-hypothesis, in a number of the cells the translocated X, Xt, or the normal X, Xn, was the late-replicating chromosome. In a few cells both Xt and Xn were late labeled, which was interpreted as perhaps the result of somatic segregation. In some of the cells showing a late-replicating Xt, the autosomal segment, which is normally early replicating, was labeled; this observation was interpreted as a position effect. The genetic material lost comprised the product of the reciprocal translocation, consisting of the centromeric region of chromosome 15 and the telomeric region of the long arm of the X. The severe clinical anomalies of the patient were ascribed to the inactivation of the translocated autosomal segment observed in a part of the examined cells.

ISSN:1424-8581    

DOI:10.1159/000130131

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The Venezuelan vole mouse, Akodon urichi venezuelensis, is a small South American cricetid which can be reared in the laboratory. Their somatic chromosomes have been morphologically and statistically investigated. The chromosome number is 2n = 18. The eight pairs of autosomes are metacentric; four pairs are similar in size and arm ratio, but the others are easy to identify. In males there is an XY sex-chromosome pair; the X is a submetacentric and duplicate type. Polymorphism has been found in the small-sized Y chromosome; in two out of six individuals it was an acrocentric and in the remaining four, a fully telocentric chromosome. In the females, the two X chromosomes are slightly heteromorphic; there is an X! quite similar to the male X chromosome and a longer X2, which differs also from the X1 in arm ratio. The risk of reversals of order in similar chromosomes is discussed.

ISSN:1424-8581    

DOI:10.1159/000130132

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

In 0- to 2-day-old bandicoots (Perameles nasuta and Isoodon obesulus) both sex chromosomes were retained in all skin and gut cells examined. Elimination of one X chromosome had occurred in some spleen cells and in all liver cells examined in a 10-day-old female P. nasuta. In a 24-day-old male I. macrourus the Y chromosome was absent in all (three only) spleen cells examined and in more than half of the liver cells. Both X chromosomes were present in all corneal cells of a 55-day-old female I. macrourus, but in the same animal only one X was present in all spleen and bone-marrow cells examined. Sex-chromosome elimination in bandicoot tissues occurred at much later stages of morphogenesis than does the appearance of sex-chromatin bodies in the cells of eutherian mammal embryos. Thus sex-chromosome inactivation probably occurs much later in bandicoots than it does in eutherian mammals.

ISSN:1424-8581    

DOI:10.1159/000130133

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The chromosomes of 344 early chick embryos (16 to 18 h of incubation) were examined. These embryos were derived from two related lines of broiler-type stock, a line selected for rapid growth rate and a companion line that had been random bred as controls. Of the 344 embryos examined, 282 were obtained from the rapid growth line and 62 from the random-bred controls. A high frequency, 38 of 344, or 11.0%, of these embryos were found to be either entirely or partially composed of cells with abnormal karyotypes. The frequencies of these abnormal embryos in the two lines were 36 of 282(12.7%) in the rapid growth line and 2 of 62 (3.2%) in the control line. Abnormalities observed included: one case of a trisomic/monosomic mosaic involving chromosome No. 1, two haploid embryos, four triploid embryos, four haploid/triploid mosaics, seven haploid/diploid mosaics, sixteen diploid/tetraploid mosaics, one haploid/ diploid/tetraploid mosaic, one haploid/diploid/tetraploid/octaploid mosaic, one diploid/ tetraploid mosaic which also involved sex-chromosome aneuploidy (2A/4A with ZZW/ZZZZWW), and one case of chromosomal rearrangement. Examination of the pedigrees of the abnormal embryos revealed that several mating pairs had produced a number of embryos with similar abnormalities.

ISSN:1424-8581    

DOI:10.1159/000130134

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Seven populations of wild sheep (Ovis ammon) were studied in northern Iran. Analysis of 34 individuals demonstrated that the eastern populations possess a 2n = 58, including 1 pair of metacentric and 27 pairs of acrocentric autosomes. The 2n for the three western localities is 54, characterized by 3 pairs of metacentric and 23 pairs of acrocentric autosomes. In two intermediate localities animals with the following diploid numbers were collected: 2n = 54, identical to western locality animals; 2n = 55, containing five metacentric autosomes; 2n = 56, containing four metacentric autosomes; 2n = 57, with three metacentric autosomes; 2n = 58, identical to the eastern two localities. The X and Y chromosomes are a large acrocentric and a small biarmed chromosome, respectively, in every specimen. The taxonomy of Iranian wild sheep and several evolutionary factors are considered in the light of these chromosomal data. The nonconformity of currently accepted theories on the origins of domestic sheep with the karyological data now available for wild palaearctic and domestic sheep is discussed.

ISSN:1424-8581    

DOI:10.1159/000130135

出版商:S. Karger AG    

年代:1971

数据来源: Karger