摘要:

Within the elite Drysdale breed of sheep, an incidence of 26.3 % of chromosome polymorphism, among a total of 327 animals studied cytogenetically, is described. Sheep were found which were both heterozygous, 2n = 53, and homozygous, 2n = 52, for a Robertsonian-type translocation. Pedigree examination of one flock suggests that the translocation chromosome had been present in some sheep of the Drysdale breed for several generations and probably since its formation. The long arms of the translocation chromosome are believed to incorporate a different acrocentric chromosome from that seen in the previously described Massey I translocation. Tentatively, the translocation has been named the Massey III translocation, and the implications of this high level of chromosome polymorphism are discussed in respect to the likely effects of impaired fertility and alternatively hybrid vigor. Two sheep which were translocation heterozygotes were found with varying degrees of segmental aplasia of their genitalia.

ISSN:1424-8581    

DOI:10.1159/000130194

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

Vandeleuria o. oleracea, a rodent, has an odd diploid number of chromosomes (2n = 29) in somatic and germ cells of males as well as in somatic cells of females. The odd element, which is constantly present in both sexes, is a member of a sex-chromosome complex, for it forms a characteristic sex heterotrivalent during male meiosis. In both somatic and germ cells of the male, an X1X2Y multiple sex-chromosome complex is present. In the female, only somatic cells have been studied, and in these an X1X1X2complex is found. The relative length of the presumptive X1 is 3.3 ± 0.06% and of the X2, 2.1 ± 0.08% of the haploid complemen

ISSN:1424-8581    

DOI:10.1159/000130195

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

The Algerian hedgehog (Aethechinus) has a diploid chromosome number of 48, similar to the European hedgehog species (Erinaceus) and to the long-eared Asiatic hedgehog. There are, however, differences in the size and structure of individual chromosomes. As compared with the European hedgehogs, which display three large blocks of distally located autosomal constitutive heterochromatin, there are only two such segments in the Algerian hedgehog. They are characterized by the following properties, of which some may apply to constitutive heterochromatin in general: heteropyknosis, late DNA replication, chromocenter formation, nucleolus-organizing capacity in the interphase nucleus, and asynchrony in the process of meiotic pairing. Deviating from findings in other species, the heterochromatic segments in the hedgehog fail to stain strongly following the conventional G- and C-banding techniques and do not show bright fluorescence after QM staining. However, when the preparations are subjected to extreme conditions of denaturation and reassociation, the heterochromatin shows marked C-banding. The different response to these dyes and to these staining techniques of various chromosomes and animal species may indicate the existence of several types of constitutive heterochromatin.

ISSN:1424-8581    

DOI:10.1159/000130196

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

A cytogenetic analysis of two anuran species, Xenopus laevis laevis and Xenopus muelleri, was performed. The diploid number of chromosomes in both species was 2n = 36. The two karyotypes, arranged according to size of chromosome and centromere position, showed no pronounced differences. However, the chromosomes which had a secondary constriction were different. In X. laevis this constriction (nucleolar organizer) was found on one pair of acrocentric chromosomes only, the pair showing association in about 50% of the metaphases. In X. muelleri, on the other hand, two distinct pairs of submetacentric chromosomes contained secondary constrictions. Neither of these two chromosome pairs was morphologically similar to the constriction-bearing chromosomes of X. laevis. Association similar to that in X. laevis was found in one pair only, the one with a terminal constriction. In neither of the two species was there any evidence of sex-chromosome heteromorphism.

ISSN:1424-8581    

DOI:10.1159/000130197

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

Karyotypes of allopatric Egyptian and Israeli mole rats (Spalax ehrenbergi) suggest that these populations share common ancestry. Palaeontological data (faunal and climate) provide evidence that the two populations have been separated for 10,000 to 25,000 years. The combined evidence implies chromosomal stability since isolation and constitutes the best estimate for length of karyotype stability known for mammals.

ISSN:1424-8581    

DOI:10.1159/000130198

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

The karyotype of the pig (Sus scrofa domestica) was characterized by means of quinacrine mustard staining and fluorescence microscopy. The material examined consisted of 15 pigs of the Danish Landrace, five boars and 10 sows, representing five boar lines and eight sow strains. Previously it had been possible to identify only six pairs of chromosomes and the Y chromosome among the 38 chromosomes of the pig. With the present method it was possible to identify both autosomes and sex chromosomes with great reliability. Fluorescence variants were not demonstrable.

ISSN:1424-8581    

DOI:10.1159/000130199

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

The C-band and G-band patterns of Microtus agrestis metaphase chromosomes are described. The C-band pattern reveals constitutive heterochromatin as uniformly intenselystained areas but cannot aid in identifying autosomal pairs. The G-bands revealed by a heat renaturation method (ASG) were compared with those revealed by treatment with three proteolytic enzymes. All procedures yield apparently the same specific pattern of crossbands on the autosomes, and each autosomal pair can therefore be identified by its characteristic pattern. The constitutive heterochromatin of the sex chromosomes stains uniformly with the heat renaturation method but is subdivided into regions with different staining intensities with each enzyme treatment. A G-band karyotype for Microtus agrestis metaphase chromosomes is presented.

ISSN:1424-8581    

DOI:10.1159/000130200

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

The chromosomes of the Chinese hamster established cell line CHEF-125 were studied by quinacrine fluorescence, acetic-saline-Giemsa staining, and a technique for localizing constitutive heterochromatin. The modal chromosome number was 22, but there were, in approximately equal proportions, two karyotypes with 22 chromosomes which differed by one chromosome only. Thirteen of the 22 chromosomes were normal ones and could be divided into five pairs of homologs and three in the haploid status. One chromosome was deficient for part of the short arm but otherwise normal, and one chromosome had an additional, unidentified segment. Of the seven new chromosomes, five were not identified, but two had sections of heterochromatin of the type and extent found in the sex chromosomes of the normal complement. One of these was composed in part of the long arm of the X chromosome.

ISSN:1424-8581    

DOI:10.1159/000130201

出版商:S. Karger AG    

年代:1972

数据来源: Karger