3 NOVEL FAMILIES OF MINIATURE INVERTED-REPEAT TRANSPOSABLE ELEMENTS ARE ASSOCIATED WITH GENES OF THE YELLOW-FEVER MOSQUITO, AEDES-AEGYPTI

Three novel families of transposable elements, Wukong, Wujin, and Wune ng, are described in the yellow fever mosquito, Aedes aegypti. Their c opy numbers range from 2,100 to 3,000 per haploid genome. There are hi gh degrees of sequence similarity within each family, and many structu ral but not sequence similarities between families. The common structu ral characteristics include small size, no coding potential, terminal inverted repeats, potential to form a stable secondary structure, A+T richness, and putative 2- to 4-bp At-T-biased specific target sites. E vidence of previous mobility is presented for the Wukong elements. Ele ments of these three families are associated with 7 of 16 fully or par tially sequenced Ae. aegypti genes. Characteristics of these mosquito elements indicate strong similarities to the miniature inverted-repeat transposable elements (MITEs) recently found to be associated with pl ant genes. MITE-like elements have also been reported in two species o f Xenopus and in Homo sapiens. This characterization of multiple famil ies of highly repetitive MITE-like elements in an invertebrate extends the range of these elements in eukaryotic genomes. A hypothesis is pr esented relating genome size and organization to the presence of highl y reiterated MITE families. The association of MITE-like elements with Ae. aegypti genes shows the same bias toward noncoding regions as in plants. This association has potentially important implications for th e evolution of gene regulation.