Development of transposon-vector-systems in insects.

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Transformation techniques are most important to analyze gene functions in model organisms, e. g. a mutant is transformed with a wild-type gene or a modified one. In insects, effective method for transformation had not been developed except for Drosophila. Using a transposable element, P-element, Drosophila can be transformed with high efficiency. Another advantage of this method is that tha most transgene is inserted with single copy and it eases to analyze given gene functions.The aim of this project is to develop transformation system using transposable elements. The materials used in this study are : Drosophila melanogaster, a mosquito species (Aedes albopictus) and the silkworm (Bombyx mori). Some species of mosquito are known as vectors for diseases, e. g. malaria, dengue. The silk worm is a useful insect not only for the textiles but also for the production of biomolecules from fibroin-gland. Therefore, an effetive transformation systems were desired in these species.Electroporat … More ion method is now widely used to transform organisms from bacteria to mammals. We tried to aply this method to insects using Drosophila embryos. In preliminary experiment with a cloned alpha-amylase gene as a reporter gene, the amylase activity was detected in the third instar larvae. Using P-element vector and a helper, however, no transformant was obtained out of 3000 embryos.To apply an eye color gene as a transformation marker, eye color mutations of Aedes albopictus were induced by Ethyl methan sulfonate (EMS). Until now, two mutations were identified. One is brown eye1 located on the sex-chromosome and anther is brown eye2 located on an autosome.Bm1 is a kind of SINE element of Bombyx mori. We had determined the complete sequences of fifteen of complete Bm1.1 elements. Sequence comparisons and a phylogenetic tree showed that they are classified into three groups. These results suggest that Bm1 was originated from tree ancestral elements and dispersed in the genome by reverse-transcription. Less