In most insects, the peritrophic matrix is thought to play a major role in food digestion and absorption. The peritrophic matrix is an acellular sheath that lines the entire intestine and is secreted by the cardia, an organ located at the Drosophila foregut/midgut junction. One aim of this proposal is to study the function of genes that encode peritrophic matrix components. Another aim is to study organogenesis of the cardia during embryonic development. Genes that are expressed specifically in the adult cardia were isolated in Dr. Jacobs-Lorena's laboratory and will be characterized to determine patterns of expression, DNA sequence, and gene function. To identify genes that play a determinative role in the genesis of the cardia, he will use a newly developed P-element/beta-galactosidase vector in a screen for genes that are expressed specifically in embryonic cardia precursor cells. These studies will be complemented by cell ablation experiments that will assess the importance of cell-cell interactions and should define the contribution of different cell types to the formation of the peritrophic matrix. %%% In insects that transmit human diseases, the peritrophic matrix interacts directly with parasites and modulates their transmission. Understanding how the organ that secretes this matrix is formed and functions will have practical implications as well as adding to our knowledge of organogenesis.
