Gulo Acts as a de novo Marker for Pronephric Tubules in Xenopus laevis

Backgrounds/Aims: Vitamin C is an antioxidant and acts as a cofactor for several key enzymatic catalytic reactions in animals. Amphibians produce vitamin C in their kidneys, as opposed to mammals that produce vitamin C in their liver. Gulo serves as a crucial enzyme for vitamin C synthesis in mammals, but the characteristics and localization of its homologous genes during kidney development in Xenopus laevis, an amphibian, remains unknown. Methods: We aligned amino acid sequences of Gulo across different species by using bioinformatics methods and detected patterns of expression for Gulo during kidney development by using RT-PCR and in situ hybridization. Results: We identified a new site on the X. laevis genome, LOC495407. Sequence alignment analysis indicated this fragment is highly conserved and homologous to gulo genes in mammals. RT-PCR and in situ hybridization results reveal that X. laevis gulo is maternally expressed during the early stages of embryonic development, particularly, in the tubules of the pronephros from the middle tail-bud stage and onward in embryos. Conclusion: Gulo is a novel specific marker for pronephros tubules in X. laevis, and may be used as a potential marker for kidney development studies and disease diagnosis in mammals