The Regulatory Mechanism Of Signaling Pathways On Insect Wing Development

Wing is one of the most important organs required for insect survival. To study the developmental mechanisms of wing helps us to solve the problems including insect evolution, organ development and pest control.As a holometabolous insect, Drosophila melanogaster is an important model to study many biological issues. The adult wing of Drosophila comes from the larval wing disc, which undergoes a complecated developmental process including cell proliferation, cell morphogenesis and cell fate differentiation. During the development, the wing disc is divided into anterior/posterior (A/P) compartments and dorsal/ventral (D/V) compartments by A/P compartment boundary and D/V compartment boundary, respectively. The cells in each compartment derive from different cell lineages, but there are no morphological changes in the boundary cells. It is still unknown how the boundary cell morphogy is regulataed.As a transcription factor, optomotor blind (omb) is a target of Decapentaplegic (Dpp) signaling pathway to regulate the wing disc development. When omb is lost, the morphology of A/P compartment boundary cells is changed. The cells are shorter along their apical-basal axis and form a fold along the A/P compartment boundary. It suggests that omb suppresses the A/P fold formation, and as a consequence, the adult wing is normal. Many signaling pathways play an essential role in cell morphogenesis, such as Hedgehog (Hh), Dpp, Wingless (Wg), Notch (N), Hippo (Hpo), and c-Jun N-terminal Kinase (JNK). In this study, we systematically studied which signaling is invloved in the Omb regulated A/P compartment boundary cell morphogenesis and disected the molecular mechanism of boundary cell morphogenesis in Drosophila wing discs.By using abundant genetic tools and manipulating gene expression levels, we detected the cell morphology, cell death, and transcription level of relevant genes after immunostaining. We found that:(1) Loss of omb activated N/Wg signaling which was required for A/P fold formation.(2) JNK pathway, which is downstream of N/Wg signaling, induced A/P fold formation.(3) Yki signaling, which is downstream of both N/Wg and Hippo pathways, was activated in A/P fold cells and promoted cell survival which was required for the A/P fold formation. In addition, Yki is parallel to JNK pathway. These results demonstrate that omb regulted A/P boundary morphogenesis is mediated by a comprehensive regulation of several signaling pathways including N/Wg-JNK and N/Wg-Yki.Another part of this thesis is about the transcriptome analysis of Locusta migratori. Locust is one of the main agriculrual pests in China. Because of the migration potential, the locust invasion is very severe when it is broadly happened. We hope to find more genes relevant to wing development in locust using transcriptome assay and provide more gene information for studying the green control of locust invasion. Meanwhile, we compared the transcriptomes of incomplete holometabolous locust and holometabolous corn borer to find the difference of regulatory genes in wing development. We used the fifth instar nymph of locust wing disc to constructed the cDNA library and got the transcriptome information by high-throughput sequencing. Then we compared our results with published transcriptome of corn borer and found that a lot of wing development related genes were conserved in these two insects. We performed further analysis of the expression profile using RT-PCR and constructed the phylogenetic trees. These data provide us many hints to follow up the study of locust wing development.