| Sea cucumber,an important marine invertebrate,shows high nutritional and commercial values.However,sea cucumber possesses strong ability of autolysis,which leads to severe deterioration in its quality during processing,storage and transport.The proteins were extracted and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)durin g autolysis of sea cucumber Stichopus japonicas body wall at 4℃ and 46℃.The results showed that the protein fractions removed from sjBW were mainly noncollagenous proteins with molecular mass about 200 kDa and 44 kDa,respectively,as comparison with proteins from tilapia fish(Oreochromis niloticus).These two proteins were identified as major yolk protein(MYP)and actin,respectively,from holothurian species by liquid chromatography-mass spectrometry(LC-MS/MS)with significant scores.After 5-6h at 46℃,the noncollagenous proteins of sjBW showed great autolytic degradation.Furthermore,the effects of cysteine protease inhibitors,including E-64,iodoacetic acid,antipain and whey protein concentrate(WPC)on autolytic degradation of noncollagenous proteins of sjBW were investigated on this condition.The results indicated that the autolytic degradation of MYP and actin were inhibited by E-64,iodoacetic acid,antipain and WPC.These results suggest that cysteine proteases are involved in autolysis of sea cucumber Stichopus japonicas body wall.The regulation of several kinds of genes in S.japonicus body wall induced by UV irradiation was investigated by reverse transcription-polymerase chain reaction(RT-PCR)with cytochrome b as internal control.The total RNA from S.japonicus body wall was extracted by Trizol method.The results indicated the mRNA expressions of cathepsin C,fibrinogen-like protein A,senescence-associated protein and major yolk protein were significantly enhanced by 71.4±44.8%,27.1 ±18.4%,43.7±21.6%and 165.5± 122.7%,respectively.These results suggest these genes may be involved in autolysis of sea cucumber body wall. |
