CLONING AND TISSUE EXPRESSION OF FOUR WNT GENES IN YELLOW CATFISH PELTEOBAGRUS FULVIDRACO AND THEIR RESPONSE TO COPPER EXPOSURE

Four full length Wnt cDNA sequences, designated Wnt5a, Wnt5b, Wnt7a and Wnt9b, were amplified by RT-PCR and RACE approaches from yellow catfish Pelteobagrus fulvidraco. The validated cDNAs of Wnt5a, Wnt5b, Wnt7a and Wnt9b were 1984, 2905, 2158 and 1622 bp in length, encoding peptides of 375, 375, 350 and 358 amino acid residues, respectively. The amino acid alignment and phylogenetic analysis revealed that Wnt sequences were relatively conserved among different vertebrates. All Wnt mRNAs were expressed in tested tissues (brain, spleen, kidney, gill, heart, muscle, mesenteric fat, liver and ovary) but with variable levels. Cu exposure for 28 days highly induced Wnt7a mRNA levels only at 30 μg Cu/L group. Cu exposure had no impact on mRNA levels of Wnt5a, Wnt5b and Wnt9b at day 28. On 56-day Cu exposure, mRNA levels of Wnt5b were not lowest at 60 μg Cu/L group and Wnt9b were the highest at 30 μg Cu/L group. Wnt5a and Wnt7a showed no significant differences among three groups. The present study indicated that functional differentiation exists in members of Wnt family, and some members may mediate the effect of Cu exposure on ovary development of yellow catfish.