Cloning and expression of Hoxc6 gene from Pampus argenteus and its relationship with pelvic fin absence.

Hoxc6 gene can be described as having roles in axial patterning in early embryogenesis, and in at least some species, having a contribution to limb positioning. In this study, we cloned and characterised Pampus argenteus Hoxc6. The highly conserved HOXC6 protein sequence contains a homeodomain and a low-complexity region. Expression of Hoxc6 mRNA was measured at different developmental stages and in different tissues by real-time PCR (p < 0.05), and was high during eye capsule and brain differentiation stages, but low in 7 and 13-day-old larvae. Hoxc6 mRNA was more abundant in fin tissue than brain and eye tissues. Western blotting showed that HOXC6 protein levels were high at embryonic stages, but decreased significantly in 7, 13, 16 and 19-day-old larvae, and levels were essentially consistent with those of mRNA measured by real-time PCR in different tissues. In situ hybridisation showed that the Hoxc6 transcript was strongly expressed in the whole brain and anterior part of the body axis in 1-day-old larvae, but in the hindbrain, pectoral fin, mandible and hypothetical pelvic fin region in 7, 13, 16 and 19-day-old organisms. These results clarify the expression and localisation characteristics of Hoxc6 gene in P. argenteus, and provide a theoretical basis for the molecular mechanism of pelvic fin loss in silver pomfret.