Dissertation > Biological Sciences > Molecular Biology > Genetic engineering (genetic engineering)

Study on Gene Expression and Function of Chitinase and Chitin Synthase in the Silkworm, Bombyx Mori

Author KongLingZuo
Tutor XuShiQing;SiMaYangHu
School Suzhou University
Course Special Economic Animal Feeding
Keywords Silkworm Chitinase gene Chitin synthase gene Expression Function
Type Master's thesis
Year 2010
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Chitin insects and other arthropods, nematodes and fungi specific to an important class of biological polymers, support insect epidermis, trachea, and intestinal epithelial Peritrophic the film cuticle. Chitin metabolism dependent on two kinds of chitin synthase and chitin-degrading enzyme and organism development to adapt to the strict chitin synthesis and degradation of coordination. Insect growth and metamorphosis strictly dependent on the structural changes in the ability of the chitin-containing tissues and organs, control of insects and other invertebrates chitin synthesis and degradation, it is possible to achieve its growth and development, and even control of life. Therefore, the control of chitin synthesis and degradation of specific new insecticides and fungicides. More than 60% of agricultural pests belonging to Lepidoptera, safe and efficient control method has great practical significance. This article relies on silkworm genome database resources, the use of molecular cloning, RACE, bio-informatics, RNAi and other technical means, the lepidopteran insect model silkworm chitin synthase homologous gene BmChsA in BmChsB and chitinase gene BmChi- The h and BmCht study, the main results are as follows: (1) for the first time in Silkworm cloned cDNA fragment the chitin synthase of homologous genes BmChsA and BmChsB, 4943bp, 3055bp. Findings of the temporal and spatial expression the the BmChsA gene specificity the larvae head and body wall tissue expression, and BmChsB gene expression in intestinal tissue; raised during the molting period BmChsA level of gene expression, while the level of gene expression in BmChsB down. RNAi studies found that age sleep silkworms injection of 5 ug / head BmChsA of gene dsRNA or siRNA injection after 36 h, respectively, a 10% and 40% of individuals with abnormal molt. Larvae molt abnormal performance of individual smaller, semi-molt and molt three. Molting the abnormal larvae epidermis BmChsA level of gene transcription was also significantly down-regulated siRNA treatment effect was significantly better than the dsRNA processing. The 4 instar silkworm injected silkworm the chitinase BmChi-h gene and BmCht of gene 5μg dsRNA / head, no phenotypic abnormalities individual. 3. 4 instar silkworm Bombyx mori injection of 20-hydroxy ecdysteroids the ketone (20E), 12 h after the old epidermal necrolysis, new epidermal renewable phenomenon molting precursor, 36h, 60h some individuals have completed molting, compared with the control group, and juvenoid Methoprene processing silkworm early 36h, the Methoprene smear treated 4th instar larvae of the silkworm growth and development with the control no significant difference. 4 instar silkworm silkworm hormone treatment gene expression profiles found, 20E significantly increase the level of the larvae head and epidermal the chitinase gene BmChi-h and BmCht of expression, short-term suppression chitin synthase gene BmChsA the The expression level of BmChsB this inhibition to be restored after 30h after treatment. The Methoprene processing expression of chitin synthase gene BmChsA BmChsB, suggesting metabolic regulation mechanisms may differ. 5 different exogenous hormone-induced physiological conditions, the a Bombyx mori head and body wall chitinase the gene BmChi-h gene and BmCht gene maintain a very similar trend, indicating that these two genes in the silkworm body plays very similar effects. Silkworm chitin synthase BmChsA in the the larvae head and body wall specific expression BmChsB specific expression in the body wall;, BmChsA level of gene expression has been than BmChsB gene in the silkworm 4th instar larval body wall, but 4L-60 h larvae close to sleep, the expression of BmChsB gene is Methoprene treatment suppression, 20E, almost at the same time significantly improve the 4L-36 h after the larval body wall BmChsA gene and BmChsB gene's expression level, the silkworm BmChsA with BmChsB gene by hormone regulation changes , speculate Drosophila fruit flies CHS-1 and CHS-2, the adjustment mode is similar to the same regulatory mechanism.

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