| Stichopus japonicus was an important economic species in our country.Due to the increased in market demand and overfishing of sea cucumber resources worldwide,as well as germplasm degradation in the breeding process,which had affected the sea cucumber industry sustainable development.Therefore,developing high quality varieties and increasing breeding diversity were the driving force for the healthy development of the sea cucumber industry,as well as an important way to maintain the development of the industry.In the breeding of new strains of sea cucumbers,in additional to conventional goals such as disease resistance,stress resistance and rapid growth,body color had also become an important trait in breeding,because the body color of sea cucumbers had a significant impact on its market price.The body color of Stichopus japonicus variable,mainly green,red and black.In recent years,researchers had successfully cultivated purple and white color morphs Stichopus japonicus offspring with stable inheritance of body color.Purple and white color morphs Stichopus japonicus had broad market prospects,but there was a lack of research on the nutritional value of these two new color morphs.In the research,green,purple and white Stichopus japonicus were used as research object to analyze and compare the nutritional components of the body walls;the polysaccharides of green and purple Stichopus japonicus had been separated and purified and the biological activities of fucosylated chondroitin sulfate in the regeneration of zebrafish fin,the main results are as followed:(1)The nutrient composition in body walls of three color morphs Stichopus japonicusThe results showed that the protein content in green sea cucumbers was significantly lower than in purple and white sea cucumbers(p < 0.05),the fat content showed no significant differences(p > 0.05),and the crude polysaccharide contents in green and purple sea cucumbers were higher than in white sea cucumbers(p < 0.05).A total of 17 amino acids were determined in the sea cucumbers,with the purple and white sea cucumbers containing higher amino acid contents(almost 48%),while the contents in the green sea cucumber was almost44%.The contents of amino acids such as lysine,phenylalanine,threonine,and valine in purple and white sea cucumbers were significantly higher than in green sea cucumbers.The linoleic acid(LA),arachidonate(ARA),timnodonic acid(EPA),and docosahexaenoic acid(DHA)had higher proportions than other polyunsaturated fatty acids in the three sea cucumbers.As an important polyunsaturated fatty acid,LA in both the purple and white sea cucumbers was significantly higher than in green sea cucumbers(by almost 4.6 times,P<0.05).The ARA contents in purple and white sea cucumbers were also significantly higher than in green sea cucumbers,while the EPA and DHA contents were significantly lower(p < 0.05).Additionally,we found that iron was the highest among the microelements in all sea cucumbers,and iron was significantly lower in purple sea cucumbers than in green and white sea cucumbers.The manganese content in green sea cucumbers was significantly higher than in purple and white sea cucumbers,and chromium was significantly higher in white sea cucumbers than in green and purple sea cucumbers.Therefore,the nutritional composition of the three body color variants of sea cucumbers were quite different,and all of them have values for further development and utilization.(2)Separation and purification of Fucosylated chondroitin sulfate(FCS)The crude polysaccharides of green and purple color morphs Stichopus japonicus were extracted by the papain method and were separated and purified by DEAE-Sepharose Fast Flow anion exchange resin,the sodium chloride solution gradient elution was used and obtain3 components.After concentration,dialysis and desalination,the purity and molecular weight of polysaccharides were identified by high performance gel permeation chromatography.The results showed that the G-FCS and P-FCS both present a single peak with high purity,and the molecular weights of G-FCS and P-FCS were 19.5 k Da and 18.8 k Da,respectively.Infrared spectroscopy showed that G-FCS and P-FCS both had the structure of fucosylated chondroitin sulfate.Atomic force microscope observations showed that P-FCS polysaccharide molecules presented a slender chain-like structure,and G-FCS polysaccharide molecules presented a spherical shape.(3)Biological activities of Fucosylated chondroitin sulfate(FCS)in zebrafish fin regenerationFucosylated chondroitin sulfate(FCS)from green and purple sea cucumbers were investigated for their promotion effects on the regeneration of fin of zebrafish larvae.Zebrafish larvae were amputated at 3 days post fertilization(dpf)and then treated with 100 mg/L polysaccharides solution for 4 hours.The results showed that two FCSs had the different effects on promoting the regeneration.P-FCS increased the regrowth area of fin of zebrafish larvae at 48 hours post amputation(hpa)significantly and changed the locomotor behavior at24 hpa(p < 0.05),but G-FCS showed no significant change on regrowth area of fin(p > 0.05).The transcription levels of the genes involved in regeneration signaling pathway of fin such as wnt10 a,msx1b,fgf20 a,bmp2a,and bmp4,were up-regulate in the amputation zebrafish larvae following P-FCS treatment(p < 0.05),while G-FCS treatment changed the transcription levels of msx1 b,bmp2a,bmp2 b and bmp4(p < 0.05).Moreover,both FCSs had immunoregulatory activity,it might achieved through FCSs binding to Toll like receptors(TLRs)to activate the NF-?B signaling pathway.P-FSC promoted the expression levels of inos?tnf-??il-6?il-10 and ifn-?,and significantly increased the contents of NO and IL-1?protein.G-FCS increased the transcriptional level of il-6,and increased the content of NO,while significantly decreased the protein content of TNF-?.Furthermore,both of FCSs also exhibited significant antioxidative effects on regeneration of zebrafish larvae and increased the contents of CAT,SOD and G6PD(p < 0.05).In conclusion,this research compared the nutritional value of green,purple and white color morphs Stichopus japonicus,and also investigated the biological activities of G-FCS and P-FCS on the regeneration of zebrafish fin.This research provided a theoretical basis for the nutritional evaluation,further utilization and development of different color morphs Stichopus japonicus and also provided a reference for the study of natural regeneration and wound healing agent. |
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