Influence of microcystin on the phagocytosis of haemocytes in crayfish (Procambarus clarkii)

In this experiment, a new method was used for observing the phagocytosis of haemocytes in Procambarus clarkia.Escherichia coli were used as phagocytic source, which could express enhanced green fluorescent protein. The haemocytes of crayfish were exposed to different concentrations of microcystin (MC) for 4 h. Then, the dynamic changes of phagocytosis of haemocytes were explored.Combined with fluorescence inverted microscope, author could intuitively and accurately observe the phagocytic cells and the whole phagocytosis process. The result showed that the phagocytosis percentage of haemocytes had no significant differences in each group. The percentage of phagocytosis in the blank group (L-15 haemocytes nutrient solution + methanol) presented an upward trend compared to the control group (L-15 haemocytes nutrient solution). The phagocytosis percentage of experimental group 1 (L-15 haemocytes nutrient solution+1 μg/L MC-LR), experimental group 2 (L-15 haemocytes nutrient solution+10 μg/L MC-LR), experimental group 3 (L-15haemocytes nutrient solution+100 μg/L MC-LR) and experimental group 4 (L-15 haemocytes nutrient solution+1000 μg/L MC-LR)showed a downtrend; and there was a certain dose effect. The phagocytic index had an significant differences between the control group and other groups; in which there were significant differences between the control group and experimental group 1, experimental group 2 and experimental group 3. While the control group and four experimental groups had no significant difference, there were also no significant differences between each experimental group. It demonstrated that the enhanced green fluorescent protein in E. coli could express stably and sustainably. We could intuitively and accurately observe the phagocytic cells and the whole phagocytosis process, draw the phagocytic percentage and the phagocytic index quickly and accurately. After MC-LR exposure, the phagocytic index of the crayfish haemocytes significantly reduced. Thereby the crayfish immunity was affected.