Transgene design to silence Aa-dcr2 in the midgut of bloodfed females and molecular characterization of transgenic mosquito lines. A) Five hundred base-pair (bp) cDNAs in sense and anti-sense orientations corresponding to a portion of Aa-dcr2 were used for the inverted repeat (IR) construction. Sense and anti-sense cDNA fragments of Aa-dcr2 were separated by the small intron of the Aa-sialonkinin I gene and placed downstream of the Aa-carboxypeptidase A promoter. A transcription termination signal derived from SV40 was added downstream of the IR construct. Numbers below the diagram indicate sizes in bp. Abbreviations: ma. left, ma. right = left, right arms of the Mos1 Mariner transposable element (TE); AeCPA promoter = promoter region of the Ae. aegypti carboxypeptidase A gene; dcr2 = cDNA fragments corresponding to the Aa-dcr2 gene; i = minor intron of the Ae. aegypti sialokinin I gene; svA = transcription termination signal derived from the SV40 virus; EGFP = green fluorescent protein marker; 3xP3 = eye tissue-specific promoter. B) Percentage of midgut-specific silencing of Aa-dcr2 mRNA among nine different transgenic Ae. aegypti lines at 1 day pbm. Aa-dcr2 expression levels in midguts of bloodfed females were normalized for gene expression levels of sugarfed females of the lines at the same time point. Bloodmeals were obtained from mice. Each sample consisted of total RNA from a pool of 20 midguts.
Khoo et al. BMC Microbiology 2010 10:130 doi:10.1186/1471-2180-10-130