Expression Study of Pluripotency Marker Genes in Gold Fish, Carassius auratrus

Abstract

Aquarium fishes, like medaka, zebrafish and goldfish offer an excellent model to conduct studies on molecular mechanisms of embryonic developmental pathways, patterns of genes involved in pluripotency and cell fate decision. To determine the possible candidate gene as an ideal pluripotency marker in goldfish, the comparative study on quantitative expression of a set of genes were conducted in the mid-blastula derived inner cell mass (ICM) and adult somatic cells. Present work explored the expression pattern of four standard pluripotency genes i.e. Nanog, Oct4, Sox and Pou2 in blastocytes (ICM) as well as somatic tissues of kidney, liver, heart, brain, muscle and mature gonads of goldfish using RT-qPCR. Absolute copy number of mRNA transcripts was calculated for each gene in every tissue. Significantly high (P<0.05) mRNA transcript number of all the genes was recorded in ICM, compared to other somatic tissues. Maternally inherited genes like Nanog, Pou2 and Oct4 were found to be highly expressive in ICM as well as in oocytes. The expression profile showed that Nanog andOct4 could belong to similar group where expression is limited to ICM and gonads whereas Pou2expressing in almost all the tissues, including ICM and adult gonads. Because of the low expression level in ICM than in the ovary, Sox2 exhibited expression in several somatic tissues apart from the gonad. Therefore these genes could be characterized as stem cell marker but not a pure pluripotency marker. The results showed that although all the genes compared in this study can be considered as stem cell markers but Nanog gene could be employed as a pure pluripotency marker for ES cell lines from goldfish.