The Response Of C-type And G-type Lysozyme In Large Yellow Croaker (Larimichthys Crocea) To Vibrio Anguillarum

Large yellow croaker(Larimichthys crocea),which belongs to the bony fish,is a famous economic native species in China Seas.But with the higher density and intensively aquaculture mode,Large yellow croaker aquaculture have various diseases every year.So studies on the immune factors affecting resistance to diseases were carried out to understand their relationship with disease resistance,which will provide the theoretical base for molecular breeding of Large yellow croaker.In this thesis,the Large yellow croaker c-type and g-type lysozyme genes were identificated and characterized,the full length of c-type and g-type lysozyme genes ORF were identificated,respectively.The expression of the mRNA was examined by FQRT-PCR.The study's main results were as follows:1.The large yellow croaker full genome sequencing sketches was used for two lysozyme gene CDNAs sequences and related software were used to analyze them: c-type and g-type lysozyme gene CDNA complete length is 763bp(XM-010753143.1)?879bp(XM-010740410.1),respectively.Encoded amino acids respectively is 111 aa ?193aa.The relationship for c-type lysozyme between the fish and the mammal is closer,for g-type lysozyme,the fish is closer to the bird.2.In this study,real time PCR method was used to investigate the two genes expression patterns in various tissues of healthy fish.The mRNA expressions of c-type and g-type lysozyme were all expressed in wide range of adult tissues,with the highest level of expression of these genes detected in the intestine.3.Two Large yellow croaker genes expression patterns in various tissues of healthy fish after challenge with Vibrio anguillarum by Real time PCR method:In liver,spleen and kidney tissues,c-type lysozyme expression in treatment group was lower than those in the control group,but infection for Vibrio after 6h,c-type lysozyme is significantly increased in the kidney.The g-type lysozyme expression in treatment group is increased at first and then decreased in liver,spleen and kidney tissues,but they have peaks in different time.Inliver,the expression for g-type lysozyme with Vibrio treatment reached a high peak at12 h,but the expression with ploy(I:C)treatment is at 24 h.In spleen,the expression with two experimental groups reached peaks is at 36 h.In kidney,with Vibrio and ploy(I:C)treatment,the expression for g-type lysozyme reached peak are in 36 h and 48 h,respectively.Bacterial challenge experiments showed that the levels of g-type lysozyme gene expression was up-regulated in three tissues of adult large yellow croaker.The c-type lysozyme gene expression was under to the control group.The results showed that g-type lysozyme gene expression was influenced by bacterial stress and it may play an important role in immunity mechanisms,and c-type lysozyme gene may play an important role in digestion.This study will further our understanding of the function of c-type and g-type lysozyme genes and the molecular mechanism of innate immunity in teleosts.