The possibility of ascorbate biosynthesis in early development of Persian sturgeon

In the present study, for the first time in a primitive fish species, the possibility of ascorbate biosynthesis during early development of Persian sturgeon was investigated via the evaluation of mRNA expression and GULO enzyme activity. The results showed that GULO gene is expressed in all developmental time-points of Persian sturgeon from eyed eggs (embryonic stage) to juvenile fish in both mRNA and protein levels. This suggests that: (i) Persian sturgeon can synthesize ascorbate; (ii) The ascorbate synthesis probably starts already before hatching. The mRNA expression of GULO was highest at embryonic stage (two days before hatching; P<0.05) and started to decline from hatching of larvae to the rest of developmental time-points. The GULO activity was detected in all developmental time-points of Persian sturgeon. However, Statistical analysis of the results indicated that the observed changes in the GULO activities were not significant (P>0.05). Our results suggest that some parts of vitamin C requirement must be fulfilled by endogenous formation of ascorbic acid during early larval development stages of sturgeon fish.