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5 Folia Biologica

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Intra individual variation in the number of B chromosomes in the yellow-necked mouse, Apodemus flavicollis (Mammalia, Rodentia)

100%

Vujosevic M. J. V. , Blagojevic J.

Folia Biologica

2005

tom 53

nr 1-2

75-78

The yellow-necked mouse, Apodemus flavicollis, is characterized by a frequent occurrence of B chromosomes. The frequency of intra individual mosaicism of Bs was studied in 995 animals collected at six localities in Serbia. It was found that 329 (33.06%) possessed B chromosomes. Among these, 87 animals (26.44%) were mosaics. A total of 32 mosaic animals with more than one B chromosome were analyzed for distribution of Bs which was found to be quite different between groups of animals with different numbers of Bs and increases with their number. The frequency of mosaics differs between localities and ranges from 0.22 to 0.55.

B chromosomes in two fish species genus Rhamdia (Siluriformes, Pimelodidae)

100%

Fenocchio A. S. , Bertolo L. A. C. , Takahashi C. S. , Camacho J. P. M.

Folia Biologica

2000

tom 48

nr 3-4

105-109

Specimens belonging to two fish species genus Rhamdia were cytogenetically analysed from seven localities in Brazil and Argentina. In addition to the 58 chromosomes of the basic karyotype, one to five metacentric B chromosomes were observed carrying conspicuous heterochromatic blocks on the distal regions of both chromosome arms. These B chromosomes are mitotically stable and, in the two best-sampled populations in R. hilarii (Lobo and 29 reservoirs), they showed frequency distributions fitting a binomial distribution, though Bs were more frequent in the latter. The presence of B chromosomes with the same appearance in R. quelen suggests an ancient origin for these B chromosomes, presumably prior to speciation from a common ancestor.

Evidence of B-chromosomes in the karyotype of Barypeithes pellucidus Boheman 1834 (Coleoptera, Curculionidae, Entiminae) from central Europe

100%

Holecova M. , Rozek M. , Lachowska D.

Folia Biologica

2005

tom 53

nr 1-2

65-68

B-chromosomes were observed in spermatogonial mitotic metaphases, meiotic metaphases I and II of Barypeithes pellucidus from one population in Slovakia. The number of B-chromosomes ranged from one to six per cell and they paired with the sex heterochromosomes in the first meiotic metaphase and rarely with the autosomes. In metaphase I one B-chromosome was always associated with X chromosome forming a tripartite complex. The XyBp was easily recognizable as a complex of three chromosomes in a parachute association The size of the B-chromosomes was approximately the same or a little smaller than that of the y heterochromosome which was the smallest element of the regular chromosome set. Their staining intensity seems to be similar to that of the autosomes and sex chromosomes, respectively. The behaviour of B-chromosomes during mitosis and meiosis in weevils is briefly discussed.

Cytogenetic studies of Glomeris (Diplopoda: Glomeridae)

88%

Warchalowska-Sliwa E. , Maryanska-Nadachowska A. , Kania G.

2004

tom 52

nr 1-2

67-71

Karyotypes and meiosis of Glomeris hexasticha and G. connexa (Diplopoda: Glomeridae) from Poland were described using C-heterochromatin distribution and observations of the location of NORs. These species were characterized by 2n>=16 and the XY sex determination system. Differences were found in the amount of C-heterochromatin in X and Y chromosomes between the studied species. In G. hexasticha, supernumerary B chromosomes were described.

B chromosomes, translocation between B and autosomes, and C-heterochromatin polymorphism of the grasshopper Podisma sapporensis Shir. (Orthoptera, Acrididae) in Hokkaido, northern Japan

63%

Warchalowska-Sliwa E. , Bugrov A. , Tatsuta H. , Akimoto S.

Folia Biologica

2001

tom 49

nr 1-2

63-75

Seven categories of B chromosomes found in the brachypterus grasshopper Podisma sapporensis from Hokkaido populations differ in structure, size, and C-band content. The interchange between B and one autosome from M3 and sporadically M7 was observed in most of the populations examined. Such an interaction between standard and non-standard chromosomal set provides an insight into the integration of supernumerary chromosome. In addition, C-heterochromatin polymorphism was also identified in male karyotypes in some populations. These facts indicate P. sapporensis is a highly polymorphic species from the cytogenetic point of view.