Effects of Temperature on Haemocyte and Granulocyte Counts and Expressions of Immunity-Related Genes in Haemocytes of Scallop Chlamys farreri After Vibrio anguillarum Infection

Abstract

Bivalve live in aquatic environment and the water temperature can affect their immunity directly. In this research, the scallop Chlamys farreri was injected with 10 ⁴ or 10 ⁷ CFU mL ⁻¹ Vibrio anguillarum and cultured at 11°C, 17°C, 23°C, and 28°C, respectively. For the control scallop, only phosphate-buffered saline (PBS) was injected. Then total haemocytes and granulocytes were measured by ELISA using monoclonal antibodies. In the meantime, expressions of six immunity-related genes, including lipopolysaccharide and β-1, 3-glucan binding protein ( CfLGBP), C-type lectin ( CfLec-2), Toll-like receptor ( CfTLR), Lysozyme ( CfLYZ), superoxide dismutase ( SOD), and phenoloxidase ( CfPO) in haemocytes were measured using quantitative real-time PCR. The results showed that total haemocytes counts in 10 ⁴ CFU mL ⁻¹ injection groups showed no differences compared to the control group at all temperatures. However, they varied significantly in 10 ⁷ CFU mL ⁻¹ injection groups at 3 h at 11°C, 6–12 h at 17°C, 3–48 h at 23°C, and 12–48 h at 28°C. Granulocytes counts in 10 ⁴ CFU mL ⁻¹ injection groups showed no variance compared to the control group at all temperatures, except for 12 h at 23°C, and 24–36 h at 28°C. They were significantly decreased in 10 ⁷ CFU mL ⁻¹ injection groups during 6–48 h at 11°C, 12–48 h at 17°C, 3–48 h at 23°C, and 3–72 h at 28°C. The expression levels of six immunity-related genes in haemocytes of 10 ⁷ CFU mL ⁻¹ injection groups were significantly higher than those of control group and 10 ⁴ CFU mL ⁻¹ injection groups at all temperatures. The results indicated that infected with high concentration of vibrios, haemocyte counts, granulocyte counts and the expressions of immunity-related genes in scallop C. farreri were significantly affected by environmental temperature.