Effects of the anti-WSSV transgenic cyanobacterial oral agent on the development, reproduction, and physiology of the Daphnia magna

Abstract

Abstract Trans-vp28 gene cyanobacteria have good efficacy as oral agent against shrimp white spot syndrome virus (WSSV) infection in shrimp and have promising applications. However, environmental safety studies of transgenic cyanobacteria are still unknown. Daphnia magna is one of the most commonly used model organism to assess toxicity of wide range of pharmaceuticals. In this study, Daphnia magna was exposed to Scenedesmus obliquus (green algae), wild Synechococcus sp. PCC 7942 (cyanobacteria), transgentic Synechococcus sp. PCC 7942 (cyanobacteria). When the D. magna were exposed to cyanobacterial water environment 21 days. The results showed the body structure of D. magna in all experimental groups was intact without any abnormalities. The shedding time of D. magna in the cyanobacteria group was faster than that of D. magna in the green algae group. The mean number of eggs and the total number of eggs laid by D. magna were not significantly different in these experimental groups. In the 7-day toxicology experiment, we measured the enzyme activities of acetylcholinesterase (AchE), catalase (CAT), glutathione S-transferase (GST) and gene transcription levels of D. magna. The results showed that there were no significant differences in AchE and CAT enzyme activities of D. magna in the three cyanobacteria groups. The GST enzyme activity of D. magna in the green algae group was significantly higher than that in the cyanobacteria groups. At the same time, there was no significant difference between the cyanobacteria-transfer pRL489 vector group and the cyanobacteria-transfer vp28 group. We found no significant correlation between enzyme activity levels and gene transcription levels in each group. The transgenic cyanobacteria have limited impact on the aquatic organism D. magna.