%0 Journal Article
%T Rhythmic expression of the cycle gene in a hematophagous insect vector
%A Antonio CA Meireles-Filho
%A Paulo R Amoretty
%A Nataly A Souza
%A Charalambos P Kyriacou
%A Alexandre A Peixoto
%J BMC Molecular Biology
%D 2006
%I BioMed Central
%R 10.1186/1471-2199-7-38
%X Here we describe the sequence, genomic organization and circadian expression of cycle in the crepuscular/nocturnal hematophagous sandfly Lutzomyia longipalpis, the main vector of visceral leishmaniasis in the Americas. Deduced amino acid sequence revealed that sandfly cycle has a C-terminal transactivation domain highly conserved among eukaryotes but absent in D. melanogaster. Moreover, an alternative form of the transcript was also identified. Interestingly, while cycle expression in Drosophila and other Diptera is constitutive, in sandflies it is rhythmic in males and female heads but constitutive in the female body. Blood-feeding, which causes down-regulation of period and timeless in this species, does not affect cycle expression.Sequence and expression analysis of cycle in L. longipalpis show interesting differences compared to Drosophila suggesting that hematophagous vector species might present interesting new models to study the molecular control of insect circadian clocks.A diversity of organisms, ranging from bacteria to humans, shows circadian rhythms in physiology and behavior that are controlled by endogenous oscillators. In mammals and flies, the core clocks are generated by two negative feedback loops that are interconnected to the same two positive basic helix-loop-helix (bHLH)/PAS-containing transcription factors CLOCK (CLK) and CYCLE (CYC) (also called BMAL1)(reviewed in [1,2]).In D. melanogaster, CLK and CYC form a heterodimer that binds to upstream E-box sequences (CACGTG) in period (per) and timeless (tim), which in turn control their own expression by negatively regulating CLK/CYC mediated activation [1,2]. In the second loop, the products of vrille (vri) and PAR domain protein 1 epsilon (Pdp1ŠĆ), which are also activated by CLK/CYC, regulate Clk transcription by competing for the same site in its promoter. Whereas VRI represses Clk production just after lights off, PDP1ŠĆ activates it in the middle of the night, separating the phases of Clk tran
%U http://www.biomedcentral.com/1471-2199/7/38