Sequence characteristics and expression analysis of <italic>FTZ</italic>-<italic>F</italic>1 gene in <italic>Chlamys farreri</italic>

Abstract

Through sequence characteristics and expression pattern analysis of <italic>FTZ</italic>-<italic>F</italic>1 gene in <italic>Chlamys farreri</italic>, this study speculated <italic>FTZ</italic>-<italic>F</italic>1 function in <italic>Chlamys farreri</italic>. The gene could not be exactly classified only by systematic evolution analysis, so sequence and expression characteristics analysis were combined, finally it was named <italic>FTZ</italic>-<italic>F</italic>1. The <italic>FTZ</italic>-<italic>F</italic>1 sequence analysis showed that the CDS (coding sequences) was 1 668 bp long, encoding 555 amino acids, including DBD (DNA binding domain) conserved region, FTZ-F1 box (FTZ-F1 box), LBD (ligand binding domain) conserved region. Multiple sequence alignment results of different species showed that conserved region of the gene was consistent with other species. The expression of <italic>FTZ</italic>-<italic>F</italic>1 in <italic>Chlamys farreri</italic> was studied by semi quantitative PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR). It showed that <italic>FTZ</italic>-<italic>F</italic>1 expression was stronger in female adductor muscle, kidney, and gill tissue, as well as the male testis, hepatopancreas, adductor muscle and kidney, the expression also existed weakly in female mantle, hepatopancreas, ovarian tissues and the male gill, mantle, the wide range of tissue expression indicated that the gene function in <italic>Chlamys farreri</italic> may be more extensive. And because the gene was expressed in gonads and liver of <italic>Chlamys farreri</italic>, we speculated that the <italic>FTZ</italic>-<italic>F</italic>1 tissue expression pattern in <italic>Chlamys farreri</italic> had the expression characteristics of <italic>NR</italic>5<italic>A</italic>2 (<italic>LRH</italic>-1/<italic>FTF</italic>) and <italic>SF</italic>-1/<italic>Ad</italic>4<italic>BP</italic> subgroup at the same time. Further study found that <italic>FTZ</italic>-<italic>F</italic>1 expressed strongly in the testis of <italic>Chlamys farreri</italic>, so its expression characteristics were believed to be more biased towards the <italic>SF</italic>-1 subgroup. The reproductive cycle of <italic>Chlamys farreri</italic> mainly included proliferation stage, growing stage and mature stage, using quantitative real-time PCR, the <italic>FTZ</italic>-<italic>F</italic>1 expression was detected in ovary and testis during the reproductive cycle. The result showed that the expression of <italic>FTZ</italic>-<italic>F</italic>1 had no significant change during the entire gonadal developmental period in ovary, but had changed during gonadal developmental in testis. At the proliferation and growth stages, there was no significant difference of <italic>FTZ</italic>-<italic>F</italic>1 expression in testis (<italic>P</italic>>0.05), while there was a significant increase (<italic>P</italic><0.05) at the mature stage in testis, the expression in mature testis was not only significantly higher than that of the other stages, but also higher than expression in ovaries during the whole gonadal development. This study suggests that <italic>FTZ</italic>-<italic>F</italic>1 plays an important role in testis at mature stage, it is speculated that <italic>FTZ</italic>-<italic>F</italic>1 may be related to the increase of testosterone content.