Rebecca A Mosher
Work Summary
Dr. Mosher studies methylation of DNA in plants and how these epigenetic marks are transmitted from parent to offspring.
Dr. Mosher studies methylation of DNA in plants and how these epigenetic marks are transmitted from parent to offspring.
This preprint has been reviewed and is currently being revised for publication at Plant Journal.
PMID: 21511999;PMCID: PMC3131103;Abstract:
The fission yeast clade - comprising Schizosaccharomyces pombe, S. octosporus, S. cryophilus, and S. japonicus - occupies the basal branch of Ascomycete fungi and is an important model of eukaryote biology. A comparative annotation of these genomes identified a near extinction of transposons and the associated innovation of transposon-free centromeres. Expression analysis established that meiotic genes are subject to antisense transcription during vegetative growth, which suggests a mechanism for their tight regulation. In addition, trans-acting regulators control new genes within the context of expanded functional modules for meiosis and stress response. Differences in gene content and regulation also explain why, unlike the budding yeast of Saccharomycotina, fission yeasts cannot use ethanol as a primary carbon source. These analyses elucidate the genome structure and gene regulation of fission yeast and provide tools for investigation across the Schizosaccharomyces clade.
In plants, the most abundant class of small RNAs are 24-nucleotide short interfering (si)RNA. These siRNAs are produced at thousands of discrete genomic locations through the action of the plant-specific DNA-dependent RNA polymerase IV (Pol IV). Pol IV-dependent siRNAs catalyze repressive DNA methylation on transposable elements and other repetitive sequences, but might trigger diverse chromatin modifications at distinct genomic locations, such as DNA demethylation or histone modification. Pol IV-dependent siRNAs are expressed abundantly, and sometimes exclusively, in the developing endosperm, where they are produced from only the maternal chromosomes. The biological role of Pol IV-dependent siRNAs is unclear, but might involve interaction between different genomes or alleles, or stabilizing and buffering the genome from genetic and epigenetic modifications.