Cloning of the functional domains of the ultraspiracle (USP) gene in the blood sucking bug Rhodnius prolixus
Angelica Nakamura1; Renata Stiebler1,2; Daniel Rodrigues Furtado1; Francisco Bastos Oliveira1; Isabel Caetano de Abreu da Silva1; Hatisaburo Masuda1; Eliane Fialho2; Marcelo Rosado Fantappie1; Marcus Fernandes de Oliveira1
1 - Instituto de Bioquímica Médica/CCS/UFRJ; 2 - Instituto de Nutrição Josué de Castro/CCS/UFRJ
Many of highly prevalent diseases in the world such as malaria, dengue fever and Chagas disease are transmited by hematophagous insects. One of the main strategies developed to reduce the spread of these diseases is based on the control of vector population through the use of insecticides. Several juvenile hormone (JH) analogs have already been synthesized aiming their use as insecticides since JH regulates many events in insects such as embryogenesis, moult and immune response. These effects are mediated by a class of nuclear receptors named ultraspiracle (USP) which are orthologs of the vertebrate retinoic acid receptors, controlling the expression of target genes. Here, we cloned and analyzed a partial sequence of the blood sucking insect Rhodnius prolixus USP (RpUSP) gene. This sequence, of 879 bp length, was obtained from a cDNA library of anterior midgut in TriplEx2 vector and comprises both the DNA binding domain (DBD) of 64 aminoacids and the ligand binding domain (LBD), with 155 aminoacids. Analysis of the in silico translated sequence show that the predicted RpUSP protein has high similarity with the orthologues from the Locusta-Blattella-Melipona group than to the Amblyomma-Aedes-Drosophila group. RT-PCR experiments reveled the presence of USP in salivary glands, fat body and ovaries and a semi-quantitative RT-PCR indicated that this gene is more expressed in ovaries than in fat body and salivary glands. Moreover, expression of USP in fat bodies increased during blood digestion. Previous data from our group indicate that injection of 4th instar nymphs with putative USP ligands, such as 9cis-retinoic acid, caused morphological aberrations upon moulting. So, we injected 120 pmoles of 9-cis retinoic acid or JH in the hemocoel of R. prolixus females, which resulted in an increase of USP expression. Thus, the results presented here show that an authentic USP is coded in R. prolixus and suggest that some of the USP functions in this insect may depend on ligand binding.
Financial support: CNPq, FUJB, Faperj, TWAS.
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