Study On The Mechanism Involved In Autolysis Of Sea Cucumber Guts--the Effect Of Digestive Enzymes And Expression Of Several Kinds Of Genes

Sea cucumber(Stichopus japonicus)is one of the most important echinoderm species,and is susceptible to changes in environmental condition.Under the extreme stress,it is easily subjected to autolysis,which leads to severe deterioration in sea cucumber quality during handling and storage.In this thesis,the effects of digestive enzyme inhibitors on autolysis of sea cucumber guts were studied.On the other hand,the regulation of several kinds of genes in S.japonicus guts induced by UV irradiation(58 pW/cm2,30 min)was investigated by reverse transcription-polymerase chain reaction(RT-PCR)with cytochrome b as internal control.The effects of digestive enzyme inhibitors on degree of autolysis of sea cucumber guts were investigated by using TCA-soluble oligopeptides and reducing sugar as evaluation indicators.The results indicated that different inhibitors,including pepstation,trypsin inhibitor,serine protease inhibitor,amylase inhibitor and ?-1,3-glucosidase inhibitor showed inhibitory effects on autolysis of S.japonicus guts in a certain range of concentration.These results suggest digestive enzymes,including pepsin,trypsin,serine proteases,amylase and?-1,3-glucosidase may be involved in autolysis of S.japonicus guts.Moreover,the results of gene expression study indicated that mRNA expression of several protein molecules were changed in S.japonicus guts induced by UV irradiation.Cathepsin L,cytochromen c,protease inhibitor Epill,chaperonin containing TCP1(subunit 4),calreticulin,major yolk protein,ependymin-related protein precursor and collagen alpha-2 and fibrinogen-like were significantly up-regulated(p<0.05).Other genes,such as aminin binding protein,beta-tubulin,histone H2,angiopoietin-like 7,cathepsin C,senescence-associated protein,collagen alpha-1,ELAV-like protein,MGC81823 protein 1 isoform 1,syndecan,actin,oncoprotein,basic leucine zipper and W2 domains 1 and Krueppel-like factor 2 were not affected by UV irradiation.In addition,matrix metalloproteinase-14,acetylcholinesterase and Laminin subunit were significantly down-regulated(p<0.05).These results suggest that these genes with significant expression change may be involved in UV-induced autolysis of S.japonicus guts.