This project is a collaborative, integrated biochemical/genetic study of chitin metabolism in a pest species (red flour beetle) that is economically important, has a completely sequenced genome, and has a well-developed genetic toolkit for functional genomic follow-through. Chitin, a structural carbohydrate polymer, is an essential component of the insect cuticle (the equivalent of the skin) and also found in the lining of the midgut. Since chitin is not present in higher animals or plants, chitin metabolism represents an insect-selective target that can be exploited for specific control of pest insects without harm to those that are deemed beneficial. The recent completion of the sequencing of the beetle genome funded by NSF-NHGRI has enabled the identification of most if not all of the genes from this insect, which are important for chitin synthesis, modification and turnover. The functions of each of these genes will be analyzed by the technique of RNA interference (RNAi), which results in specific down-regulation of the products of selected genes. The morphological, physiological and developmental effects of RNAi experiments targeted towards individual genes of chitin metabolism will be determined and compared with the effects of selected "chitin inhibitors," which are commercially utilized for insect control. The proteins encoded by these target genes will also be purified and the effects of chitin inhibitors on their activities will be confirmed. The knowledge obtained from these studies will help identify novel target physiological processes for insect pest control purposes. This project will also help train post-graduate, graduate and undergraduate students in the field of insect functional genomics at an EPSCOR institution. Undergraduate students from underrepresented minorities and women will be encouraged to participate in our research both during the academic year and summer months. In particular, attempts will be made to recruit students from minority institutions utilizing the ongoing SUROP, McNair and NSF-REU programs.
Intellectual merit The major objective of this grant was to identify and characterize several genes encoding proteins that are essential for the synthesis and turnover of a major component of the insect cuticle (equivalent of human skin), namely chitin. The chitin and other components in the cuticle protect the insect from mechanical injury and predation. Without chitin insects will lose the rigidity of the cuticle and will be susceptible to environmental stresses and to other predators and insect pests. Because chitin is absent in animals and plants, it is an attractive target for selective insect control. Our research has identified several genes that control the synthesis of chitin and its dissolution. Some of the proteins have critical roles in organizing the chitin in the cuticle. Loss of the function of many of these genes leads to defects in molting, loss of fertility and mortality of the insects. We have identified some genes that appear to be useful targets for development of selective insecticides. We have published 15 research publications in major journals in our discipline. Broader impacts We have trained one research associate, five graduate students and several undergraduate students during this grant. The research training received in our laboratory has benefitted them to advance in their careers. The research associate has accepted a faculty position in a major university this year. Our graduate students have joined major research institutions to carry out post-doctoral research. Many of the undergraduate students are now pursuing careers in science. We are maintaining colonies of beetles with different genetic traits that are used by high school teachers as tools for their genetic courses. Every year, we train several scientists from many institutions in methodologies for beetle manipulations and gene inactivation strategies. Our work has identified several ideal target genes that affect insect development and viability. These findings may pave the way for developing plants that are resistant to selective pest insects in the near term. In the longer term, these strategies may be applied to control other insects such as mosquitoes that carry vectors causing human and animal diseases.
