One consequence of global climate change is a shift in the seasonal distribution of medically and economically important insect species. As temperatures increase many species are emerging earlier in the spring and producing more generations per year, thus having a bigger impact on human well being. Knowing how insects coordinate their seasonal development with appropriate seasons for growth and development is critical for predicting changes in seasonal distribution of key insect species. Much of the year is unsuitable for continuous development and during this time many insects enter a period of dormancy known as diapause. Diapause allows insects to "escape" from predictable periods of harsh environmental conditions. Characterized by arrested development and reduced metabolism, diapause significantly increases an insect?s lifespan in addition to providing protection from environmental extremes. The aim of this research is to further our understanding of the molecular basis of diapause by examining the regulatory role of microRNAs (miRNAs) in initiating and maintaining diapause in the flesh fly, Sarcophaga bullata. miRNAs are small RNA fragments that post-transcriptionally regulate gene expression. They represent one type of epigenetic mechanism that can change the phenotype (i.e., morphological or physiological attributes) of an organism without changing the underlying DNA sequence. These small RNAs appear to be essential for diapause because genes that encode components of the miRNA processing machinery are more highly expressed in diapausing S. bullata pupae than in their non-diapause counterparts. miRNAs are known to regulate biological processes that are important for establishing and maintaining diapause, including developmental timing, metabolism, and stress-resistance. These studies will also provide new information about the maternal inheritance of miRNAs and the influence of maternal history on the expression and activity of miRNAs. In S. bullata a maternal effect prevents diapause in offspring of females that have gone through diapause. Maternal effects commonly regulate diapause in insects, especially in Diptera, but little is known about how such maternal effects are regulated by miRNAs or any other factor. Together, this research is expected to provide entirely new information about the regulation of diapause and the seasonal patterns of insects that are a consequence of diapause. Understanding how miRNAs regulate the maternal block of diapause in the female?s progeny may provide new tools to manipulate the diapause response and, ultimately, control population outbreaks of insect pests. In addition to providing new information about how diapause is regulated, this research will generate some of the first miRNA sequences for a non-Drosophila fly. We anticipate that the new miRNA sequences will help provide a foundation for future studies on the evolution of insect miRNA sequences and establish a framework for understanding the ecological relevance of these small RNAs in the adaptations of animals to an ever-changing environment. This research will provide training for a postdoctoral researcher, and graduate and undergraduate students. It will also enable members of the laboratory to continue their outreach programs with local elementary schools, high schools and public libraries in the Columbus area.
