Effects of cadmium stress on the expression of C-type lectin gene and some physiological indexes of Pinctada fucata martensii
[Objective]To clarify the immune response mechanism of Pinctada fucata martensii to cadmium stress,which could provide theoretical basis for enriching the immunological studies of shellfish.[Method]Using 2-year-old P.fucata martensii as the research material,2 C-type lectin(CTL)genes(PmCTL1 and PmCTL4)of P.fucata martensii were cloned through the RACE technique,and real-time fluorescence quantitative PCR was used to detect the expression of the 2 genes in various tissues of P.fucata martensii.P.fucata martensii were stressed with a 4.0 mg/L cadmium chloride(CdCl2)solution,and the hepatopancreas and hemolymph tissues were collected at 0,3,6,12,24 and 48 h after stress to detect the expression of PmCTL1 and PmCTL4 genes in the hepatopancreas and the activity changes of serum acid phos-phatase(ACP),catalase(CAT)and superoxide dismutase(SOD).At the same time,a 21 d stress experiment was con-ducted with a 0.5 mg/L cadmium chloride solution,and the changes in the hepatosomatic index(HSI)of P.fucata marten-sii were observed and statistically analyzed.[Result]The full-length cDNA sequences of the cloned PmCTL1 and PmCTL4 genes were 853 and 1113 bp respectively,and the corresponding encoded proteins each contained 1 typical CRD domain CRD.The CRD domains all had 6 conserved cysteines and showed high similarity to those of other mollusks.The PmCTL1 and PmCTL4 genes were expressed in various tissues of P.fucata martensii,including the hepatopancreas,go-nads,adductor muscle,gills and mantle,but they exhibited different tissue expression patterns.The relative expression levels of PmCTL1 and PmCTL4 genes in the hepatopancreas showed a clear fluctuating trend over time with cadmium stress.At 6 h of cadmium stress,the relative expression levels of both were at their lowest.The PmCTL1 gene reached its highest value at 3 h of cadmium stress[approximately as 3.23 times as that of pre-cadmium stress(0 h)],and the PmCTL4 gene reached its highest value at 12 h of cadmium stress[approximately as 2.03 times as that of pre-cadmium stress(0 h)].The serum ACP activity of P.fucata martensii reached its peak at 24 h of cadmium stress,CAT activity peaked at 6 h of cadmium stress,and SOD activity peaked at 3 h of cadmium stress.The HSI of P.fucata martensii gradually decreased over time with the progression of cadmium stress.[Conclusion]Under cadmium stress,P.fucata martensii experiences obvious immune stress.The PmCTL1 and PmCTL4 genes,as well as serum ACP,CAT and SOD,all respond to cadmium stress.This indicates that CTL and serum enzymes play important roles in the detoxification process of cadmium in shellfish,with the primary activity occurring in the hepatopancreas tissue.
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维普
