Growth and Antioxidant-Related Effects of the Reestablished Ascorbic Acid Pathway in Zebrafish () by Genomic Integration of L-Gulonolactone Oxidase From Cloudy Catshark ().

Loss of L-gulonolactone oxidase (), which catalyzes the last step of the ascorbic acid (AA) biosynthesis pathway, results in a complete lack of AA in several Osteichthyes fish species, including zebrafish. In this study, , the active gene from cloudy catshark () was cloned into zebrafish using the Gateway cloning method. The resulting fish were analyzed for the effects of a reestablished AA pathway. Fluorescent microscopy and PCR were used to analyze the integration of the construct into the zebrafish genome. Catalytic activity of sGULO, AA production, growth-related characteristics, and gene expression were investigated to evaluate the effects of AA production in fish. The mCherry fluorescent protein indicated the proper integration and expression of the construct in zebrafish. The gene was ubiquitously expressed in all the studied tissues and the enzyme activity indicated an increased AA production in fish. The growth of fish was also increased, and antioxidant system analysis suggests that reactive oxygen species production was reduced in fish compared with wild type. Expression of the AA transporter was significantly downregulated in homozygous fish. These results collectively indicate the effects of reestablished AA synthesis in zebrafish.