Molecular characterization and functional analysis of adrenergic like receptor during larval metamorphosis in Crassostrea angulata
- 生命科学－已发表论文 
Numerous reports have associated the catecholamines with larval settlement and metamorphosis in bivalve mollusks. However, little information about the receptors during larval development is available. In this study, for the first time we clone and characterize the cDNAs designated as adrenergic-like receptor (AR(cga)) from Crassostrea angulata. The deduced protein AR(cga) has high similarity with alpha(2)-adrenergic receptor (alpha(2)-AR) from Ixodes scapularis, and includes three major domains composed of a transmembrane domain with seven transmembrane motifs, a relatively long third cytoplasmic loop and a short fourth inner terminal domain. Using a real-time PCR approach, expression profiles of the AR(cga) were analyzed in adult tissues and during larval development. In adult oyster, the AR(cga) was expressed ubiquitously, although transcript levels varied between organs; the highest mRNA level was detected in labium followed by mantle and gonad. AR(cga) expression increased during larval development and reached the highest level at eyespot larvae, and then the expressions were maintained in a high level during metamorphosis. The temporal and spatial expression profile of mRNA was examined from trochophore to eyespot larva stages by whole mount in situ hybridization. In the four stages, AR(cga) mRNA was mainly detected in the cerebral ganglion and or the apical organ, the pedal ganglion and around the heart. The ganglion differentiation was found in the early umbo-veliger larva. To evaluate the possible regulation of AR(cga) by adrenaline in the oyster metamorphosis, competent larvae were exposed to the neurotransmitter adrenaline. AR(cga) expression increased for the first 12 h after treatment and then AR(cga) mRNA level decreases gradually to the same level of untreated control group. Overall, these results suggest that AR(cga) might play a considerable role in signal transduction during the larval metamorphosis of C. angulata (C) 2012 Elsevier B.V. All rights reserved.