Functional analysis of ABCG2 gene in pigment transport of Neocaridina denticulata sinensis

Many strains of Neocaridina denticulata sinensis (cherry shrimp) possess vivid body colors.However, the molecular underpinnings of these various body colors are scarcely understood. To study the role of the ABCG2 gene in the pigmentation of cherry shrimp, four strains (red, yellow, blue, and wild strains) were sampled. The sequence and expression pattern of ABCG2in tissues and embryos were analyzed, and the distribution of ABCG2 was also explored via WFISH (whole mount flurescence in situ hybridization). And further, RNA interference (RNAi) was used to explore the role of ABCG2 in body color deposition. The results showed that the ABCG2 sequence contained the conserved motif of Walker A, Walker B, Q-loop, d-loop, and H-loop. In tissues, ABCG2 was highly expressed in the epidermis of the four strains. During development stages, it was first expressed at the cleavage stage, then decreased at the gastrula stage, with the lowest expression at the pre-nauplius stage. From the metanauplius stage, its expression level was significantly upregulated until it reached the highest level at the membrane-zoea stage. WFISH showed that ABCG2 was first expressed at the cleavage stage in all four strains, and its distribution was similar from the cleavage stage to the before-zoea stage. The strongest positive signals were observed at the membrane-zoea stage, which was consistent with the qPCR results. Moreover, at the membrane-zoea stage, the positive signals of the four strains were mainly distributed in the compound eye and appendages. RNAi knockdown of ABCG2 encumbered the development of compound eye pigment cells (CEPCs) and erythrophores. It had effects on the expressions of other genes related to body color. These results suggest that ABCG2 is involved in the development of compound eye and the proliferation of erythrophores. This study provides new ideas for the cultivation of novel body colors in cherry shrimp at the molecular level.