Analysis of B chromosome transcripts and their involvement in B chromosome nondisjunction

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Drive is the main feature of B chromosomes (Bs) in certain species of plants, especially the Gramineae, where it involves directed nondisjunction at pollen mitosis and allows the Bs to be transmitted at greater rate than Mendelian frequencies. Thus far however no gene, or nondisjunction element, on any B has yet been characterized that plays a role in B accumulation mechanisms/drive. We wish to test whether noncoding RNA is involved in the regulation of B nondisjunction. To this end Bspecific transcriptionally active high-copy repeats, which are located at the Bterminal regions (the chromosomal region which controls the process of nondisjunction), will be analyzed, together with with the hitherto uncharacterized Bspecific transcripts. In addition, we intend to analyse the process of nondisjunction at the microscopic level, in terms of differences in the chromatin composition, and centromere function between A and B chromosomes. This analysis will provide new evidence of the generation of rapid genome changes in higher eukaryotes, with particular relevance to selfish chromosomes, and will improve our knowledge of the mechanism underlying the segregation behaviour of chromosomes.