Aedes aegypti dopa decarboxylase: gene structure and regulation

Abstract

Dopa decarboxylase converts L-dopa to dopamine, a precursor molecule for diverse biological activities in insects including neurotransmission and a variety of tanning reactions required for development, reproduction and defence against parasites. Herein, we report the cloning and sequencing of the Aedes aegypti Ddc gene, including 2.1 kb of the upstream promoter region. The transcribed region of the gene spans more than 16 kb and contains five exons. In situ hybridization localizes the blood-meal-induced ovarian transcription of this gene to the follicular epithelial cells surrounding individual oocytes. Ovary tissue transcription of Ddc is increased in response to injection of 20-hydroxyecdysone to levels equal to those observed for blood-fed controls, however coinjection with the translational inhibitor cycloheximide negates the effect, indicating an indirect regulatory role for this hormone. Clusters of putative ecdysone-responsive elements and zinc-finger binding domains for the products of Broad-Complex gene family are identified in the 5'-promoter region. These elements are discussed in the context of common insect Ddc regulatory mechanisms.

Dopamine and octopamine regulate 20‐hydroxyecdysone level in vivo in Drosophila

“…This leads to a decrease in JH degradation in both (Rauschenbach et al, 2004a; Gruntenko et al, 2005a,b;Karpova et al, 2005). The effect of 20E on the metabolism of biogenic amines has also been shown in other insect species (Hiruma et al, 1985;Hiruma and Riddiford, 1990;Ferdig et al, 2000;Lehman et al, 2000;Mesce, 2002;Zufelato et al, 2004). However, in the available literature we found no research into the effects of biogenic amines on 20E levels in insects in vivo.…”

Gene expression profiling during early response to injury and microbial challenges in the silkworm, Bombyx mori

“…Because DDC is primarily detected in ovaries and DCE is constitutively expressed in adult mosquitoes (Johnson et al, 2001), it was not surprising that no change in the transcript abundance was detected. Besides playing a role in defense against pathogen infection and wound healing, the melanization-related genes, such as PPO, DDC, and DCE, also have diverse biological activities in cuticle sclerotization, neurotransmission, reproduction, and a variety of tanning reactions required for metamorphosis (Ferdig et al, 2000). These genes would have a relatively high expression level when compared to PAH, which participates in the rate-limiting step (Johnson et al, 2003), and a further increase of the concentration became unnecessary (Zou et al, 2005).…”

20‐hydroxyecdysone and juvenile hormone influence tyrosine hydroxylase activity in Drosophila females under normal and heat stress conditions

“…Thus, it was demonstrated that a rise in 20E titre changes expression of the dopa decarboxylase (Ddc) gene in larvae of Manduca sexta (Hiruma and Riddiford, 1990) and females of Aedes aegypti (Ferdig et al, 2000) and expression of the prophenoloxidase gene in pupae of Apis mellifera (Zufelato et al, 2004). The effect of JH on the expression of the Ddc gene has been found in larvae of Manduca sexta (Hiruma and Riddiford, 1990).…”