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Media type:
E-Article
Title:
Polymorphic and stable chromosomes of Sorex araneus L. differ in centromere constitution (R-banding): Evolutionary aspects
Contributor:
Halkka, Liisa;
Vakula, Nina;
Kaikusalo, Asko
Published:
Finnish Zoological and Botanical Publishing Board, formed by the Finnish Academy of Sciences, Societas Biologica Fennica Vanamo, Societas pro Fauna et Flora Fennica, and Societas Scientiarum Fennica, 1994
Published in:
Annales Zoologici Fennici, 31 (1994) 3, Seite 289-296
Language:
English
ISSN:
0003-455X;
1797-2450
Origination:
Footnote:
Description:
The karyotype of Sorex araneus L. (Mammalia, Insectivora, Soricidae) consists of the sex chromosome trivalent XY1Y2 and three stable metacentrics with chromosome arm combinations cb, fa and ut. The other twelve chromosome arms from g to r take part in extensive polymorphism with different arm combinations between races, different combinations of metacentrics and telocentrics between populations and individuals. The sex chromosomes, stable metacentrics and the poorly polymorphic arm pair j/l have moderately AT-rich centromeres. All other polymorphic chromosome arms have variable amounts of highly GC-rich centromeric heterochromatin. The GC-specific stain Chromomycin A3 (CMA) intensified with Methyl green (MG) produces a R-banding pattern with brightly fluorescent centromeric dots in polymorphic chromosomes of Sorex araneus. We developed a rapid R-band procedure with a basic buffer pretreatment (pH 8.6) followed by silver staining. This RBS-procedure first induces NOR-bands, then a succession of GC-rich cell constituents (R-bands) in the following sequence — centromeric dots — telomeric — neartelomeric — intercalary bands. This RBS-staining method is a simple tool for analysing the polymorphic chromosomes of Sorex araneus. The central role of the GC-rich centromeric heterochromatin in the evolution of the chromosomal polymorphism of Sorex araneus L. is discussed.