Identification and characterization of ABCC gene family and their roles in the response to intraperitoneal injection of microcystin-LR in liver of silver carp (Hypophthalmichthys molitrix)

Silver carp (Hypophthalmichthys molitrix) is a widely distributed food resource and phytoplankton predator in China, which has been used to control algal blooms. Silver carp is quite resistant to microcystins (MCs), which are typical hepatotoxins generated by toxic algae. ATP-Binding Cassette, Subfamily C (ABCC) transporter are critical detoxification genes that could export toxic substances out of the cell, and with regard to ABCC transporters in H. molitrix, current studies are limited. In order to investigate the roles of ABCC genes in excretion of MCs, the full-length transcriptome of silver carp was analyzed to screen a total of nine ABCC transporter genes, which were expressed ubiquitously in silver carp tissues, especially in the liver. Furthermore, microcystin-LR (MC-LR) intraperitoneal injection was performed, and the results showed that, except abcc2, abcc10 and abcc12, the expression of other ABCC genes increased rapidly within 1 h and then began to decline after 6 h. Among these five genes, abcc3 and abcc9 exhibited the most pronounced response, indicating that these two were the most preeminent detoxification genes of microcystin in ABCC genes family in silver carp. Meanwhile, the activities of glutathione-S-transferase (GST) were increased significantly, while the content of glutathione (GSH) demonstrated a dramatic decrease, implying that GST catalyzed binding of GSH and MC-LR, and then excreted through ABCC transporters. The findings of this study will be useful in further investigating the fundamental characteristics of silver carp and provide new insights into the potential function of ABCC genes in the detoxication of MC-LR.

Automated summary

Silver carp, a widely distributed phytoplankton predator in China, has been found to be resistant to microcystins (MCs), hepatotoxins generated by toxic algae. This study analyzed the full-length transcriptome of silver carp and identified nine ABCC transporter genes that play a role in the excretion of MCs. Among these genes, abcc3 and abcc9 showed the most significant response, indicating their prominent detoxification function in silver carp. The study also found that glutathione-S-transferase (GST) activity increased significantly while the glutathione (GSH) content decreased, suggesting that GST catalyzes the binding of GSH and MC-LR for excretion through ABCC transporters.