Preliminary Study On Immune Function Of Hemocyanin From White Shrimp Litopenaeus Vannamei

This article studied the effects of phosphatidyl serine (PS) and pathogens onsynthesis and phenol oxidase (PO) activity of hemocyanin from white shrimpLitopenaeus vannamei. It included two section. One centered on effects of PS onsynthesis and PO activity of hemocyanin from Litopenaeus vannamei, and the otherfocused on influences of two different bacteria on synthesis and PO activity ofhemocyanin from Litopenaeus vannamei. The main results were as follows:1Effects of PS on synthesis and PO activity of hemocyanin from LitopenaeusvannameiThe results indicated that0.25,0.5,1μg PS had a significant effect on hemocyaninconcentration, expressions of hemocyanin subunits (p75and p77) and mRNA, totalhemocyte count (THC), pro-phenol oxidase (pro-PO), PO, hemocyanin-derived PO(Hd-PO), antibacterial and bacteriolytic activities (P<0.05), while control group didnot have a significant change. Hemocyanin concentration declined slightly during6hours after PS injection and had a peak change from6thhour to36thhour with climaxat24thhour; expression of p75, p77and hemocyanin mRNA had peak changes during36hours, all reached their top value at12thhour. THC and pro-PO activity bothdeclined during12hours with minimum at12thhour; PO activity had a peak changeduring48hours with its peak at12thhour; Hd-PO activity had a peak change in36hours with its peak at12thhour. Antibacterial and bacteriolytic activities had peakchanges during36and48hours with their climaxes at12thand24thhour, respectively.This proved that PS could activate Hd-PO and cause some immune parameters tochange with significant time dose effect. PS made hemocyanin concentration declinein short time and then initiated the mechanism of hemocyanin synthesis, confirming that PS is an elicitor of Hd-PO and an immune stimulus of Litopenaeus vannamei, andlaid theoretical foundation on immune activity of hemocyanin in Litopenaeusvannamei.2Effects of Vibro harveyi and Staphyloccocus aureus on synthesis and PO activityof hemocyanin from Litopenaeus vannameiThe results showed that V. harveyi (×10~5cells/mL,×10~6cells/mL) and S. aureuswith high concentration (×10~6cells/mL) could significantly affect hemocyaninconcentration, expressions of p75, p77and hemocyanin mRNA, PO, Hd-PO,antibacterial and bacteriolytic activities (P<0.05), and control group had no significanteffect. During48hours: Hemocyanin concentration fluctuated with minimum at12thhour; expressions of p75, p77and hemocyanin mRNA all reached their peak at24thhour. PO and Hd-PO activities both climbed to climax at24thhour; antibacterial andbacteriolytic activities reached their peaks at12thand24thhour, respectively.S. aureus with low concentration (×10~5cells/mL) only affected significantlyantibacterial and bacteriolytic activities (P<0.05), with maximums at12thhour forantibacterial activity and24thhour for bacteriolytic activities. All treatments did nothad significant effects on expression of hemocyte antibacterial peptides penaedin1/2.The results demonstrated that shrimp started hemocyanin synthesis under invasionof pathogen V. harveyi and induced expression of hemocyanin gene. The hemocyaninnewly synthesized mainly acted as PO (i.e. Hd-PO) and participated in immunedefense, further improving immune regulation of pro-PO activating system in shrimphemolymph. Non-pathogen S. aureus with high concentration (×10~6cells/mL) had asame effect.