Cloning and characterisation of polymorphic heterochromatic segments of Brachycome dichromosomatica.
After selective enrichment and differential hybridisation of Cot-1 DNA fractions of plants with and without polymorphic heterochromatic segments, a repetitive sequence (called Bds1) specific to the polymorphic chromosome segments of Brachycome dichromosomatica (Brachyscome dichromosomatica) was isolated. A single repeat unit of Bds1 is 92 bp long and is organised in tandem arrays at three different polymorphic segment sites on the chromosomes of cytodeme A2. Although all three sites showed extensive polymorphism between plants, the karyotypes of all analysed mitotic root cells were stable within a single plant. Electron microscopy revealed heavily condensed chromatin structures at the most obvious polymorphic site. The mechanisms that generate and maintain the observed chromosome structure polymorphisms are discussed.
Houben
A
A
Department of Genetics, University of Adelaide, South Australia, Australia. andreas.houben@adelaide.edu.au
Wanner
G
G
Hanson
L
L
Verlin
D
D
Leach
C R
CR
Timmis
J N
JN
D001483:Base Sequence; D015139:Blotting, Southern; D027682:Cation Transport Proteins; D003001:Cloning, Molecular; D020732:Cytogenetic Analysis; D017931:DNA Primers / Q000737:chemistry; D018744:DNA, Plant / Q000032:analysis* / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D018628:Gene Dosage; D006570:Heterochromatin / Q000648:ultrastructure*; D017404:In Situ Hybridization, Fluorescence; D026901:Membrane Transport Proteins; D008677:Metaphase / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D015183:Restriction Mapping; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
C076223:COT1 protein, S cerevisiae; D027682:Cation Transport Proteins; D017931:DNA Primers; D018744:DNA, Plant; D005656:Fungal Proteins; D006570:Heterochromatin; D026901:Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins