| Apostichopus japonicus belongs to Echinodermata,Mainly distributed in the west coast of the north Pacific Ocean,in Japan,Korea and Russian far east offshore distribution,with high nutritional value.With the rapid development of market demand and aquaculture industry,sea cucumbers of different varieties and strains enter the aquaculture and consumption market.“Russian red sea cucumber”(Apostichopus japonicus)is a geographical distant species of local sea cucumber.Because it grows slowly and is slightly smaller,it is believed that it can accumulate more nutrients in the body,and the market price is higher than that of domestic common cultured sea cucumber.At present,“Russian red sea cucumber” has been introduced into domestic farming.In order to better understand the growth status of “Russian red sea cucumber”and whether the nutritional components of “Russian red sea cucumber” strain are different from the conventional cultured species in the same breeding environment,this study compared the growth data of two sea cucumbers in different periods.The quality indexes of important components such as crude protein,crude polysaccharide,fatty acid and crude saponin were measured and compared with the same breeding environment sea cucumber.In order to understand the genetic characteristics of “Russian red sea cucumber”,this study sequenced the mitochondrial genome of “Russian red sea cucumber”,and analyzed the composition of its mitochondrial genome and its phylogenetic relationship,which provided a basis for the study of mitochondrial genome of sea cucumber.The main research results are as follows:Comparing the growth data of “Russian red sea cucumber” and common sea cucumber,it was found that the body weight and the body length of “Russian red sea cucumber” in seedling stage has an advantage,and the survival rate is higher than that of common sea cucumber.The body length of “Russian red sea cucumber”,which is 1year old,is relatively lower than that of common sea cucumber in the same samplingtime;the two sea cucumbers have little change in the number of thorns,the thorn number of “Russian red sea cucumber” is relatively higher than that of common sea cucumber,the peeling rate during the period is also relatively higher than that of common sea cucumbers.It is speculated that there is an advantage in the number of thorns and body wall thickness;the survival rate varies little,and the survival rate of“Russian red sea cucumber” in each period is higher than that of common sea cucumber;The increasing trend of the weight gain rate of the two sea cucumbers is the same.The weight gain rate of common sea cucumbers at each sampling time was significantly higher than that of “Russian red sea cucumber”.The weight of “Russian red sea cucumber” was relatively lower than that of common sea cucumbers in each period.Based on the growth data of this study,it was found that the “Russian red sea cucumber” had the growth advantage at the seedling stage.The “Russian red sea cucumber” of the 1 year old had no growth advantage in terms of body weight,body length and weight gain rate,but the number of thorns,survival rate and the peeling rate shows a certain growth advantage.The crude protein,crude saponin and crude fat content of “Russian red sea cucumber” in the general nutrient composition were significantly higher than that of common sea cucumber(P<0.05),and there was no difference between crude polysaccharide and ash content.The content of Mg,Ca,Mn,Zn,Sr and Se in “Russian red sea cucumber” was significantly lower than that of common sea cucumber(P<0.05),the contents of harmful elements Cr,Cd,Pb,As and Al in“Russian red sea cucumber”were significantly lower than those of common sea cucumber(P<0.05),the content of Fe in “Russian red sea cucumber” was significantly higher than that of common sea cucumber(P<0.05),and there was no significant difference in Cr content.17 kinds of amino acids were detected in two sea cucumbers,and the 14 amino acids content of“Russian red sea cucumber ”was significantly higher than that of common sea cucumber(P<0.05).The total amino acid,essential amino acid and medicinal amino acid content of “Russian red sea cucumber” were significantly higher than that of common sea cucumber.The fatty acid composition of the two sea cucumbers was the same,and 27 fatty acids were detected.The content of unsaturated fatty acids was higher than that of saturated fatty acids,and the content of polyunsaturated fatty acids was significantly higher than that of monounsaturated fatty acids(P<0.05).The content of unsaturatedfatty acids and polyunsaturated fatty acids in “Russian red sea cucumber” was significantly higher than that of sea cucumber(P<0.05).“Russian red sea cucumber”has a slightly higher sensory score than common sea cucumber.According to the comprehensive evaluation,under the same farming conditions,the nutrients of the two sea cucumbers are similar,and the quality of “Russian red sea cucumber” is better than common sea cucumber.The results showed that the mitochondrial genome of “Russian red sea cucumber”is 16111 bp in length,and contained 37 genes,including 22 tRNA,2 rRNA(l-rRNA,s-rRNA)and 13 protein-coding genes.There were 24 gene spacing and 5 gene overlap regions;Both the protein-coding gene and the full-sequence pair base exhibit A and T bias;the highest frequency of amino acid coding is Ser,followed by Leu;the codon was complete,except ND1 with GTG as the starting codon,the others with ATN as the starting codon.Most of the termination codons are TAA,but the termination codons of ND2 and ND4 are TTG and TAG,respectively;The length of tRNA ranges from 66 to72 bp,two genes are duplicated,and 21 genes can predict their clover structure.The length and position of l-rRNA and s-rRNA are different,and the use of bases is similar;the gene arrangement of the protein-coding gene is the same as that of four sea urchins in the family Echinoidea,and shares two gene models with the families of Ophiuroidea.The genetic distance analysis showed that the “Russian red sea cucumber” was the closest to the Apostichopus japonicus from three habitats.Blast analysis showed that“Russian red sea cucumber” had the highest homology with Apostichopus japonicus.The phylogenetic tree was constructed based on the maximum likelihood method based on amino acid and nucleotide sequence,which provided a theoretical basis for the subsequent genetic research of “Russian red sea cucumber”. |
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