552B Poster - 07. Chromatin, epigenetics and genomics
Friday April 08, 2:00 PM - 4:00 PM

Authors:
Ana Dorador; Justin Blumenstiel

Affiliation: University of Kansas

Keywords:
j. pairing/transvection; j. epigenetics

Paramutation is the phenomenon by which a silent alle can turn off a normal allele in trans in an epigenetic manner. The silenced state of the wildtype allele can persist through generations even in the absence of the original paramutagenic allele. The mechanisms underlying paramutation are poorly understood. Further, little is known about how paramutation shapes gene expression under natural conditions. In this study, we investigate a system of genic paramutation in Drosophila virilis. Previous studies have shown that maternally transmitted piRNAs that target the center divider (cdi) gene in D. virilis have the capacity to silence expression of cdi in the next generation. In addition, it has been shown that piRNAs that target cdi can be maintained in subsequent generations in the absence of the original silencing allele. However, it is not known whether this pattern of piRNA biogenesis and maternal transmission coincides with epigenetic repression of cdi expression across multiple generations. To determine if cdi piRNA biogenesis mediates paramutation, we measured the expression of cdi in the ovaries of females heterozygous for the silencing allele, as well as their daughters that lack the silencing allele.
In two independent experiments, cdi expression was quantified in 20 F1 heterozygous mothers and 20 first-generation backcross daughters, lacking the original silent allele, using RT-qPCR. Confirming previous studies, we found that heterozygous females that maternally inherited the piRNA producing allele had low expression of cdi in ovaries. We further found that the first-generation backcross daughters - lacking the paramutagenic allele – had significantly lower cdiexpression in the ovaries compared to a genotypically identical strain with no piRNAs mapping to cdi. This study thus describes a new system of paramuation in gene expression of Drosophila virilis, which can serve as a baseline for future studies that seek to understand how paramutation is regulated.