Roswitha Gamperl

Genome size and heterochromatin variation in rodents

Nuclear DNA amounts are determined in 16 species and the C-banding patterns for 19 species of rodents. A list of rodent DNA amounts is compiled. The fraction of heterochromatin in the genome is determined as the length of C-banded chromosome material relative to the total karyotype length. Among all rodents, heterochromatin amounts tend to be larger in the larger genomes. However, this relationship is not exact and does not hold true for individual genera. In general the notion of a basic rodent genome of defined size to which various amounts of heterochromatin have been added is untenable.

Studies on sex chromosomes of four hamster species: Cricetus cricetus, Cricetulus griseus, Mesocricetus auratus, and Phodopus sungorus

In this paper, we present an analysis of the sex chromosomes of four hamster species after application of different staining techniques. The mitotic X chromosomes show a striking similarity in G-banding pattern but rather great differences in their C-banding patterns. A presumably homologous euchromatic segment that exhibits two distinct G-bands appears in the X chromosome of each species. The Y chromosome of Cricetus cricetus is in contrast to those of the other species, because it reveals a relatively well-differentiated G- and C-banding pattern. In meiotic metaphase I, interstitial chiasmata can be found in the sex bivalents of Cricetus cricetus and Cricetulus griseus, whereas the gonosomes of Mesocricetus auratus and Phodopus sungorus sungorus are terminally associated. The regions that are involved in pairing or association are always heterochromatic.

A comparative analysis of the karyotypes of Cricetus cricetus and Cricetulus griseus

This study presents a comparison of the mitotic chromosomes of the two species of hamsters Cricetus cricetus (European hamster) and Cricetulus griseus (Chinese hamster), which have the same chromosome number of 2n=22. — G-banding procedure reveals striking similarities in both karyotypes and gives the possibility to analyse structural changes so that two examples for Robertsonian rearrangement can be observed. — A remarkable kind of difference between the two karyotypes becomes obvious after C-banding procedure. While Cricetus cricetus shows a large amount of predominantly centromeric heterochromatin, in Cricetulus griseus C-bands are less conspicuous, and a few chromosomes do not exhibit any centromeric heterochromatin at all.

Comparison of Chromosome Banding Patterns in Five Members of Cricetinae with Comments on Possible Relationships

SUMMARYFive species of Cricetinae were investigated with regard to chromosome banding pattern homology. The strikingly coincident G-banding patterns present in Cricetus cricetus and Cricetulus griseus could not be found in the other species. Only Phodopus sungorus shows a still considerable number of homologous segments of chromosomes. The C-banded karyotypes reveal fundamental differences in amount and distribution of heterochromatin. The highest amounts of heterochromatin are found in Cricetus cricetus and Mesocricetus auratus, the lowest amount is shown by Mystromys albicaudatus. The karyotype of Cricetus cricetus is characterized by large blocks of centromeric heterochromatin, that of Mesocricetus auratus by totally heterochromatic short arms of many chromosomes. Cricetulus griseus and Phodopus sungorus possess several pairs of chromosomes without distinct centromeric heterochromatin. Each autosome of Mystromys albicaudatus reveals a small amount of heterochromatin in the centromeric region; two pairs...

Clonal chromosome aberrations in a case of cutaneous T-cell lymphoma

Cytogenetic analysis was performed on peripheral blood and on a skin infiltration from a patient with cutaneous T-cell lymphoma. The blood cells revealed no chromosome abnormalities; whereas, besides normal cells, the skin lesion yielded on aberrant clone with the following abnormalities: trisomies 8 and 17, a deletion of the short arm of chromosome 11, and formation of one marker chromosome with possible involvement of chromosome #14.

Comparative study of G- and C-banded chromosomes of Gerbillus campestris and Meriones unguiculatus (Rodentia, Gerbillinae)

Recently members of the genera Gerbillus and Meriones have repeatedly been the subject of karyological studies. Both genera comprise many species that reveal great interand intraspecific variability (Matthey, 1953; Nadler & Lay, 1967; Vorontsov & Korobitsina, 1970; Wahrman & Gourevitz, 1972; Hermann, 1973; Lay & Nadler, 1975; Lay et al., 1975; Korobitsina & Korablev, 1978). In most studies, only conventional staining techniques have been applied, but as banding techniques can provide us with much more information on chromosomal homologies or chromosomal rearrangements, it seems desirable to accumulate more data on banded karyotypes to elucidate taxonomic and phylogenetic relationships. The present paper compares the Gand C-banded mitotic chromosomes of two species of Gerbillinae, Gerbillus campestris and Meriones unguiculatus. Additionally, first meiotic metaphase of Meriones unguiculatus was analysed by use of the C-staining technique.

Karyological studies on European rats

The genus Rattus is a very common group of rodents with a great number of species mainly distributed in Asia. Only R. rattus and R. norvegicus originally distributed in Southeast Asia migrated to Europe and from there to other parts of the world (Yosida, 1973; Yosida et al., 1974). Chromosomes of Rattus species have been studied by many investigators and, therefore, a great deal of information exists about karyotype evolution in rats. The chromosome number of R. norvegicus has been reported to be 42 all over the world (Kral, 1971; Schnedl & Schnedl, 1972; Thust, 1972; Unakul & Hsu, 1972; Gallimore & Richardson, 1973; Mori et al., 1973; Yosida & Sagai, 1973; Yasnova & Gileva, 1976). All subspecies of R. rattus distributed outside of Asia have a diploid chromosome number of 38 (Bianchi et al., 1969; Capanna & Civitelli, 1971a, b; Davies & Baker, 1971; Raman & Sharma, 1972; Reig et al., 1972; Patton & Myers, 1974; Niethammer, 1975). In Asia, however, black rats with 38, 42 and the transient type with 40 chromosomes were found (Yong, 1971; Yosida. et al., 1971; Raman & Sharma, 1972; Yosida et al., 1972; Lakhotia et al., 1973; Mori et al., 1973; Yosida, 1973; Yosida & Sagai, 1973; Niethammer, 1975). Karyological differences in rats are mainly caused by pericentric in~zersions of chromosomes nos. 1, 9, and 13 and Robertsonian fusions between the acrocentric pairs 4 + 7 and 11 + 12 (Yosida & Sagai, 1972; Yosida, 1977a). Variation of constitutive heterochromatin as revealed by C-banding procedure has been reported by Yosida (1975) and Yosida & Sagai (1975) to be a further mechanism of chromosome evolution in rats. In order to study these evolutionary trends in European rats, a detailed analysis of Gbands and, especially C-bands was carried out in several populations of /L rattus rattus (Austria, Switzerland) and R. norvegicus (Austria). In addition, I obtained some individuals of R. rattus flavipectus from Hongkong, so that a direct comparison between the karyotypes of Asian and European rats became possible.

New observations on the karyotype of the Djungarian hamster, Phodopus sungorus.

In this paper, the C-banding pattern of the karyotype of Phodopus sungorus is presented and polymorphism is taken into consideration.

Chromosome abnormalities in bovine papillomavirus type 1-transformed Syrian hamster cells before and after tumor formation

Syrian hamster embryonic fibroblasts transformed by infection with bovine papillomavirus type 1 cause tumors when inoculated into hamsters. Chromosome examinations revealed several abnormal clones in the transformed fibroblasts and a variety of additional markers in three tumors. Only one aberration, trisomy 11, was present in each cell. The extra chromosome #11, thus, is considered to be essential for tumor formation in this model system.