Nature of B chromosomes in the harvest mouse Reithrodontomys megalotis by fluorescence in situ hybridization (FISH)

Authors: Peppers, John; Wiggins, Lara; Baker, Robert

Source: Chromosome Research, Volume 5, Number 7, November 1997 , pp. 475-479(5)

Publisher: Springer

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Abstract:

Using fluorescence in situ hybridization, we examined the characteristics of two types of B chromosomes in harvest mice of the genus Reithrodontomys. B chromosomes were interrogated with rDNA, telomeric repeat, LINE element and centromeric heterochromatin probes. The two types of B chromosomes share the following features: (a) telomeres present on the ends of both arms; (b) hybridization to LINE probes; (c) absence of hybridization to the ribosomal gene probes; (d) C-band-positive centromeric regions; and (e) euchromatic arms. They differ as follows: (a) the larger B element hybridizes to the centromeric heterochromatin (pMeg-1) probe whereas the smaller B element does not; (b) the amount of C-band-positive material is reduced in the smaller B chromosome relative to that present on the larger B chromosome; and (c) the smaller element is reduced in size by about a third. It is concluded that the larger B chromosome arose as a leftover centromere from centric fusion, whereas the smaller element has a different origin — perhaps as an intact fragment or as an amplified region from the A chromosomes. The presence of euchromatic regions on B chromosomes may account for their survival in the karyotype.

Keywords: B chromosomes; centric fusion; fluorescence in situ hybridization; Reithrodontomys

Document Type: Research article

DOI: http://dx.doi.org/10.1023/A:1018421114607

Affiliations: 1: Email: bjjap@ttacs.ttu.edu

Publication date: 1997-11-01