Spatial expression of silk genes in aquatic moths

Silk is used by many species of the order Lepidoptera to assist in mobility and protection during earlier life stages and spinning the pupal cocoon in the final lifestage. Silk is produced by silk glands, which consist of three sections (anterior, middle, and posterior) based on their structure and function. Silk fibers consist of a core of the structural protein fibroin, expressed within the posterior silk gland, and a coating of supporting proteins including sericins, expressed in the middle silk gland. Finally, silk is assembled in the anterior silk gland. Silk production is unique to each species' needs, resulting in differences in the size and shape of the silk glands and in the number and composition of sericins present. In our study, we focus on two species of the family Crambidae that have an aquatic lifestyle and are distributed across the southeastern United States: Samea multiplicalis and Elophila obliteralis. S. multiplicalis generates extensive trails of silk on top of aquatic plants, while E. obliteralis is more cryptic and lives between small leaf cuttings held together by silk. We hypothesize that they have specific adaptations in their silk gene expression to aid their aquatic lifestyle. We dissected their larval silk glands to reveal the spatial expression patterns of sericins and other silk genes using in situ hybridization chain reaction (HCR). Our study will determine which sericins are expressed in the different regions of the silk glands, and will inform us on the unique characteristics of aquatic silks.