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Populations of wild boar (Sus scrofa scrofa L.) of Central Europe frequently demonstrate polymorphism in chromosome number. This phenomenon is caused by chromosome rearrangements of the centric fusion type. The presence of Robertsonian translocations in the wild boar population May lead to one of three different karyotypes: 2n=36, 2n=37 and 2n=38. The aim of the study was to analyse the karyotype of five wild boar piglets (two gilts and three boars) originating from one litter, by unknown parents. The GTG-banding technique demonstrated that one boar was characterized by karyotype 38,XY, two gilts (37,XXt.rob15;17) and one boar (37,XYt.rob15;17) were heterozygotic translocation carriers while one boar (36,XYt.rob15;17) was a homozygotic carrier for a Robertsonian translocation including chromosomes 15 and 17. Thus, in this particular litter the chromosome number polymorphism was shown. A Mendelian segregation was found of the 15;17 translocation In the piglets (1:2:1 ratio) whose parents were possibly heterozygotic carriers of 15;17 centric fusion.
The application of chromosome banding methods for plant karyosystematic studies is analyzed. The authors discuss ways of constructing C-band idiograms and interpretating the results of C-banding studies with respect to the polymorphism of heterochromatin and its histochemical differentiation. The role of quantitative changes of heterochromatin in evolution, its functional effect, and the division into dispensable and indispensable heterochromatin are presented. An overview of the recent literature on this subject is also given.
Morphology of conventionally stained and C-banded chromosomes of three plant species (Allium vineale L., Secale segetale Zhuk. and S. afganicum Vav.) was investigated. C-banding was found to shorten chromosomes more than other staining methods used. Although the arm ratio of chromosomes but whole genome composition was generally unchanged. Particular chromosomes in some metaphase plates showed, however, distinct morphological modifications. Their arm ratio was enormously altered due to very uneven shortening of both chromosome arms. The mechanisms of these changes and their significance in karyotype investigation are discussed.
Significant variability in the karyotype od P. schreberi from populations in Poland was found, contrasting with high uniformity of the chromosome number. In 58 of 60 metaphases of gametophytes originating from three populations, haploid chromosome number n = 5 was counted. In two cells n= 6 was determined. In each metaphase the total and relative chromosome lengths and the arm ratio of the chromosomes were examined, and the chromosomes were ranked for these parameters. The haploid set consists of three chromosome types: metacentric, submedian and subterminal. Their frequencies in particular metaphase plates are different. The longest (A chromosome) and the smallest are highly stable in relation to the arm ratio, representing in the majority of metaphase plates the metacentric and submedian type, respectively. The A chromosome was polymorphic in respect to total lenght and the occurrence of secondary constrictions. Karyotype varied within and between populations. Eight types of karyotype were distinguished. Factors involved in karyotype variation are discussed.
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