ISSN:
1573-6849
Keywords:
chromosomal polymorphism
;
heterochromatin
;
satellite DNA
;
South American rodent
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Graomys griseoflavus is a South American phyllotine rodent widespread in Argentina that shows a high frequency of Robertsonian fusions (RFs). DNA restriction withEcoRI produced a 250-bp repeated family (EG250) specific for the genus. Southern hybridization and sequencing analysis indicate that the EG250 family is heterogeneous, comprising at least two subfamilies.In situ hybridized EG250 probe showed a centromere location in almost all chromosomes. In all karyomorphs C-banding was negative, but restriction enzyme banding (re-banding) withAluI andMboI showed centromeric blocks in the autosomes that will generate Robertsonian fusions. Thus, we found three groups of chromosomes: (a) EG250 and Re-banding negative; (b) EG250 positive and Re-banding negative; and (c) EG250 and Re-banding positive. We consider that group (b) is more the result of chromatin condensation state than that of the frequency of recognition sites for the enzymes used. Restriction enzyme blocks would appear in regions with heterochromatic EG250 subfamilies, while lack of banding would be due to decondensed EG250 subfamilies becoming an easier target for chromosomal restriction. It is suggested that heterochromatic EG250 DNA provides a favourable molecular environment for Robertsonian fusion occurrence.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00710017
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