Rbodnius prolixus Malpighian tubule's aquaporin expression is modulated by 5-hydroxytryptamine

The purpose of the present study was to detect the presence of an aquaporin-like water channel, a member of the major intrinsic protein (MIP) family, in the Malpighian tubule (MT) of the hematophagous insect Rhodnius prolixus, which excrete a large bulk of fluid after a massive blood meal, and its possible regulation by 5-hydroxytryptamine (5-HT). Reverse transcription polymerose chain reaction (RT-PCR) and Southern blots of cDNA was obtained from adult R. prolixus MT poly (A)(+) RNA. Employing degenerate primers corresponding to the NPA (amino acid sequence motifs repeats Asn-Pro-Ala) highly conserved domain of amino acids sequences of all members of the MIP gene family, we were able to identify a 365-base pair PCR product. The R. prolixus MT mRNA expression of this water transporter is increased in the animal after blood meal and in tubules treated with 5-hydroxytryptamine or cAMP. The up-regulated expression of MT MIP mRNA after a blood meal is probably due to the action of 5-hydroxytryptamine via a cyclic AMP dependent pathway. Arch. Insect Biochem. Physiol. 57:133-141, 2004. (C) 2004 Wiley-Liss, Inc.