Document Detail

Characterisation of repeated sequences from microdissected B chromosomes of Crepis capillaris.
MedLine Citation:
PMID:  8585988     Owner:  NLM     Status:  MEDLINE    
The B chromosome of Crepis capillaris was isolated from the standard chromosomes by microdissection, and the chromosomal DNA amplified using the degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). The PCR product was cloned and a B-specific library created and characterised. Southern and in situ hybridisation analyses of the DOP-PCR product from microdissected B chromosomes confirmed that the B chromosome is composed mainly of sequences also present in the A chromosomes but lacks the main repeated DNA families located in the A-chromosomal heterochromatin. From 100 clones analysed, 12% of the generated B-chromosomal library was shown to be composed of dispersed repeats located in both the A and B chromosomes. No B-specific repeated sequence was detected. One of the most abundant repeated DNAs within the library, the family B134, was further characterised. Repeating units show a sequence similarity range from 69% to 90% and are characterised by their richness in (CA)n repeats. In situ hybridisation revealed that members of this family are dispersed throughout the A and B chromosomes but are more concentrated in the pericentromeric heterochromatin of the B, indicating that the molecular organization of B heterochromatin is different from that of the A chromosomes. Compared with the A chromosomes, the Bs contain about 20,000 copies per micron more of the B134 sequence. This indicates that B134 was amplified on the B chromosome after its origin. The B134 sequences in the B chromosomes have also diverged from those on the A chromosomes. Although the DNA composition of A and B chromosomes is similar, Bs are evolving separately from A chromosomes at the molecular level.
M Jamilena; M Garrido-Ramos; M Ruiz Rejón; C Ruiz Rejón; J S Parker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Chromosoma     Volume:  104     ISSN:  0009-5915     ISO Abbreviation:  Chromosoma     Publication Date:  1995 Nov 
Date Detail:
Created Date:  1996-03-28     Completed Date:  1996-03-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985138R     Medline TA:  Chromosoma     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  113-20     Citation Subset:  IM    
Department of Botany, School of Plant Sciences, University of Reading, Reading RG6 2AS, UK.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/U26693;  U26694;  U26695;  U26696;  U26829
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MeSH Terms
Base Sequence
Blotting, Southern
Chromosomes / chemistry*
Cloning, Molecular
DNA Primers
DNA, Plant / chemistry
In Situ Hybridization, Fluorescence
Molecular Sequence Data
Plants / genetics*
Polymerase Chain Reaction / methods*
Repetitive Sequences, Nucleic Acid*
Sequence Homology, Nucleic Acid
Reg. No./Substance:
0/DNA Primers; 0/DNA, Plant; 0/Heterochromatin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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