Genotoxicity evaluation of low doses of avermectin to hemocytes of silkworm (Bombyx mori) and response of gene expression to DNA damage

DNA damage caused by low dosage of avermectin was evaluated in hemocytes of silkworm (Bombyx mori) using the alkaline single-cell gel electrophoresis (SCGE). The fourth instar larvae of silkworm were exposed to avermectin by oral feeding with mulberry leaves treated on the three different concentrations. The hemocytes were collected at day 1, 3, 5, 7, 9 for assessment of DNA damage with tail DNA percent. Results showed that there was positive correlation between avermectin concentration and DNA damage in three tested treatments. The maximum value of tail DNA percent was observed at the third day, followed by a gradual non-linear decline. For better understanding the results of SCGE at transcription level, differentially expressed genes (DEGs) were explored in hemocytes of silkworm exposed to avermectin (1.0 μg/l) using annealing control primer (ACP)-based PCR. 15 DEGs were screened and sequenced, among which 10 genes were up-regulated, 5 genes were down-regulated. These genes were related with DNA damage or DNA damage repair of hemocytes.

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► The fourth instar larvae of silkworm are treated by three low dose of avermectin.
► DNAs of hemocytes are damaged with the appearance of comet tails.
► Differentially expressed genes screened are related to DNA damage or damage repair.