Germline transformation of the major African malaria vector, Anopheles gambiae, was achieved using the piggyBac transposable element marked with the enhanced green fluorescent protein (EGFP) injected into mosquito embryos. Two G1 generation male mosquitoes expressing EGFP were identified among 34 143 larvae screened. Genomic Southern data and sequencing of the piggyBac insertion boundaries showed that these two males arose from one piggyBac insertion event in the injected G0 embryos. Genetic cross data suggest that the insertion site of the element either resulted in, or is tightly linked to, a recessive lethal. This was demonstrated by a deficiency in the number of EGFP-expressing offspring from inbred crosses but expected ratios in outcrosses to non-transformed individuals and failure to establish a pure-breeding line. The insertion was weakly linked to the collarless locus on chromosome 2 and was shown by in situ hybridization to be located in division 28D of that chromosome. Particularly high levels of expression were observed uniformly in salivary glands and, in most individuals, in the anterior stomach. An improvement in the injection technique at the end of the studies resulted in increased G0 hatching, transient expression and EGFP-expression rates among G1 progeny.

Several cDNA clones with similarity to alpha-amylases have been characterized from a library made from adult female salivary gland RNA isolated from the vector mosquito, Aedes aegypti. The corresponding gene, designated Amylase I (Amy I), is expressed specifically in the proximal-lateral lobes of the adult female salivary gland, a pattern overlapping that of another gene, Mal I, involved in carbohydrate metabolism. The deduced amino acid sequence of Amy I indicates that this gene encodes a protein, approximate M(r) = 81,500, that appears to be a novel member of the amylase gene family. The mosquito protein contains a putative signal peptide for secretion and several consensus sites for asparagine-linked glycosylation. The Amy I protein shows significant similarity to invertebrate and vertebrate amylases including the conservation of four reactive and substrate binding sites. However, the amino-terminal region of the Amy-I protein is unique to the mosquito. Similarity with the Drosophila melanogaster protein is evident only after the first 260 amino acids in the mosquito sequence. The identification of this gene and its expression pattern adds to the observed relationship between spatial-specific gene expression in the female salivary glands and the specific feeding mode of the adult mosquito.

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The sequence and tissue expression of the gene encoding a peptide hormone Aea-HP-I, known to inhibit host-seeking behavior, has been characterized for the yellowfever mosquito, Aedes aegypti (L.). The open reading frame reveals a prepropeptide that would be processed into three identical peptides. The gene contains four short introns and exists as a single genomic copy. Transcripts of the gene were present in the brain, terminal ganglion, and midgut of adults, and in females, its expression profile differed for each tissue before and during a reproductive cycle. Peptides resulting from this expression were identified in the female tissues by immunoassays. Numerous neurosecretory cells and neurons in the nervous system were immunostained by an Aea-HP-I antiserum. Hundreds of endocrine cells were stained similarly in the midgut, thus contributing to the 10 times greater amount of immunoreactive peptide in an abdomen than in a head, as determined with an Aea-HP-I radioimmunoassay. Based on these results, neurosecretory cells and midgut endocrine cells are likely sources of Aea-HPs shown to reach highest hemolymph titer at the same time as host seeking is inhibited in female Ae. aegypti during a reproductive cycle.