Identification of aquaporin-1a gene transcript in Cyprinus carpio (Linnaeus, 1758) and its expression during reproduction

Aquaporins (AQPs) are a family of membranebound proteins that facilitate the hydration of cells. The identification of the AQP1a gene in common carp (Cyprinus carpio) from mRNA transcript and its expression analysis during reproduction was performed to study its role in gonad cell hydration. The AQP1a gene transcript was partially amplified using gene-specific primers and the amino acid sequence was predicted. Based on the partial transcript sequence, a phylogenetic tree was prepared using the MEGA4 software which suggested that the AQP1a gene of common carp is closely related to that of Danio rerio. Differential tissue expression was analysed using real-time PCR which indicated that the expression of AQP1a was significantly higher in the eye, kidney, and liver with 32.98±1.33 folds higher in the eye when compared to the testis. In both the male and female gonads, the highest expressions were observed after 6h of synthetic hormone injection in comparison to gonads belonging to the individual without any injection. However, the gene expression declines gradually in 12h and 24h post-injection. Expression analysis of gonad during different phases of reproduction suggests that there is a significant increment of AQP1a expression from the resting phase to the pre-spawning phase and from pre-spawning to spawning phase in the case of male gonad. However, there was no significant difference in expression during the resting and pre-spawning phase in the female gonad, although expression was significantly higher during the spawning phase. Key words Aquaporin; Gonad; Reproduction: Common carp; gene expression