Identification of functional genes involved in Cd2+ response of Chinese surf clam (Mactra chinensis) through transcriptome sequencing

• Totally 39.9 M raw reads and 56,712 unigenes were obtained.
• 21,305 unigenes were annotated.
• Conducted an acute test of Cd2+.
• Six selected function genes were linked to Cd2+exposure.
• This study enriched the molecule genetics data of Mactra chinensis.

The Chinese surf clam Mactra chinensis is an economically important bivalve species in the coastal waters of Liaoning and Shandong Province, China. In this study, we carried out transcriptome sequencing to develop molecular resources for M. chinensis and conducted an acute test of Cd2+ stimulation through quantitative real-time PCR (qRT-PCR) to analyze the relative expression of six functional genes. A total of 100,839 transcripts and 56,712 unigenes were obtained from 39.9 million filtered reads and 21,305 unigenes were annotated by hitting against NCBI database. According to the results of qRT-PCR, heat shock protein 22 (Hsp22) and cytochrome P450 (CYP450(2C31)) were inhibited in the low concentration, and induced in the high concentration of Cd2+; thioredoxin peroxidase (TPx-A) was at normal level in low concentration, but induced in high concentration of Cd2+; glutathione peroxidase A (GPA), glutathione peroxidase 1 (GPA1) and Mn superoxide dismutase gene (MnSOD) were down-regulated when exposed to any treatment groups. Expression levels of the six functional genes following Cd2+ exposure indicated that these genes were linked to environmental stress. Moreover, the present work enriched the molecule genetic data of M. chinensis.