Rescue of oq, og and og^t mutants by injection of xanthine oxidase

Abstract

To find a rescue method for the oq mutant and to use the mutant as a host for a transgenesis in the silkworm, transplantation of fat body, testis and ovary, and injection of xanthine oxidase were performed. The mutant ovary and testis transplanted to the normal larvae became fertile. A transplantation of the normal fat body to the mutant also recovered the fertility. Since these results agree with the hypothesis that the sterility of the mutant is due to the deficiency in xanthine dehydrogenase which is produced mainly in the fat body, we examined the effect of injection of xanthine oxidase, the enzyme with the same function of xanthine dehydrogenase, in the mutant larvae. The injection changed the mutant skin color to the normal, increased the amount of uric acid and rescued the sterile mutant. In addition, the injection showed similar effect in two other oily mutants, og and og^t, which are deficient in this enzyme activity. From the results we concluded that the sterility of these mutants is caused by the deficiency of xanthine dehydrogenase activity and can be rescued by the injection of xanthine oxidase.