摘要:

Chromosome analysis was made on somatic cells in culture derived by necropsy from the ear and the peritoneum of a sex-chromatin positive male tortoiseshell domestic cat. A mixture of triploid (57, XXY) and normal diploid female (38 XX) cells was found in cultures of both tissue origins. The chimerism † probably existed in the cat and did not arise during in vitro cultivation. Several mechanisms for the origin of this particular chimera are suggested, including double fertilization and fusion of various types of fertilized or unfertilized meiotic products. It is postulated that the sex-linked allelic genes for the black and yellow coat color in cats follow Mendelian inheritance and that the tortoiseshell phenotype possibly is due to genetic inactivation of either X-chromosome in a heterozygous female. It is further suggested that a male tortoiseshell cat can possess an XXY sex chromosome constitution and be heterozygous for the sex-linked coat-color genes, but other types of sex chromosome anomalies and mosaicism can give rise to the same phenotype in males. The karyotype of the normal domestic cat (Felts domestica) is presented. Most, if not all, of the chromosomes can be identified. Certain similarities of karyotypes among members of Felidae are note

ISSN:1424-8581    

DOI:10.1159/000129794

出版商:S. Karger AG    

年代:1964

数据来源: Karger

摘要:

The 13 somatic chromosomes of a male marsupial rat-kangaroo (Potorous tridactylis apicalis) are described and measurements are given. Each of the five pairs of autosomes and the three unpaired sex chromosomes are morphologically distinct. During pachytene there are five autosomal bivalents and one sex-chromosome trivalent. In early subcultutes of muscle fibroblasts a large proportion of the cells were polyploid and there were a number of cells with extra and/or missing Y chromosomes. Because of the simplicity of its karyotype, this mammal should prove extremely useful in studies of chromosome evolution in cultured cells and experimental studies involving changes in chromosome number and structure.

ISSN:1424-8581    

DOI:10.1159/000129795

出版商:S. Karger AG    

年代:1964

数据来源: Karger

摘要:

Cytogenetic analyses of 6 unrelated 13–15/21 translocation mongols, 6 unrelated 21–22/21 translocation mongols and almost all of their parents and sibs have been carried out. Parents carrying the translocation chromosome were found in 2 of the 13–15/21 families, but not in any of the 21–22/21 families (one father could not be tested). Mean parental ages for either type of translocation mongol were not significantly different from those for the general population. No translocation mongol had a translocation mongol relative but 4 of the 12 translocation patients had a mongol relative of the standard trisomic type. In an unselected group of 96 mongols 2 were of the translocation type

ISSN:1424-8581    

DOI:10.1159/000129796

出版商:S. Karger AG    

年代:1964

数据来源: Karger

摘要:

The relationship between growth-rate changes and chromosomal changes during serial passage of adult human fibroblasts was examined. The phase of rapid growth in vitro is followed by a phase of progressively declining growth rate and finally, by a phase of cellular degeneration. The declining growth phase is associated with a rising level of tetraploid metaphases. In the degenerating phase, the tetraploid level increases further and aneuploid cells first appear. SV40-infection of cultured fibroblasts in the declining growth phase results in rapid and extensive chromosome alterations in the first few days following infection. Chromosome alterations in cultures 1 to 7 days after infection were examined in detail. There is a sharp increase in tetraploid metaphases due, in part, to endoreduplication. An increased frequency of breaks was seen within 2 days, and dicentric chromosomes were common by the 4th day. The normally occurring secondary constrictions became more pronounced and a member of the 6-X group, thought to be the late-replicating X chromosome, appeared to be preferentially lost. Telomeric associations involving most members of the complement were frequently encountered; evidence is presented indicating that these associations can lead to the formation of dicentric chromosomes. The telomeres of the long arm of chromosome 4 (or 5) in this cell strain were most often involved in dicentric formation. The rapid response of the several areas of relatively inert chromatin suggests an early viral effect on this material. The relationship, if any, between these early chromosome changes and the changes in the physiology of viral transformed cells remains to be elucidated.

ISSN:1424-8581    

DOI:10.1159/000129797

出版商:S. Karger AG    

年代:1964

数据来源: Karger

摘要:

Nuclear sizes were measured in 1000 cells each of four human fibroblast cultures, two of which were of normal XX-, and two of normal XY-karyotype. In the XX-cultures, the nuclei containing a Barr body were significantly smaller than those lacking a Barr body. The difference in size was of the order of 6%. It is suggested that the smaller nuclear size is partly a direct effect of the condensation of one X-chromosome and partly an indirect effect, Barr bodies being present mainly at those stages of the mitotic cycle when the nucleus is not at its maximum size.

ISSN:1424-8581    

DOI:10.1159/000129798

出版商:S. Karger AG    

年代:1964

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000129799

出版商:S. Karger AG    

年代:1964

数据来源: Karger