RT-PCR analysis of expression of the Anopheles gambiae genes identified in this study. (A) Expression during the course of development. M, male; F, female; L1, first instar larvae; L2, second instar larvae; L3, third instar larvae; L4, fourth instar larvae; P, pupae; A, adults. (B) Male tissue expression. H, head; T, thorax; A, abdomen; Md, midgut; Mt, Malpighian tubules; Ts, testes; Ag, accessory glands. Apart from AAms, the primers used for RT-PCR were designed to span intron regions, which allows an easy recognition of the RT-PCR signal from the amplified traces of genomic DNA contaminating the RNA samples despite DNase treatment (cf. Ams products, in which the weak upper band represents the DNA amplified from a genomic template and the lower band corresponds to cDNA fragmens). The low level of signal in AAms likely originates from residues of genomic DNA, because the amplified fragment spans an exclusively exonic region. For each sample 28 amplification cycles were performed, apart from 32 cycles for AAms in dissected tissues to visualize the short transcript. S7 was amplified in 24 cycles.