| Chinese sea cone Nassarius variciferus is an economically important small snail mainly distributed in the northern coast of China.In the previous study,our research found that the Chinese sea cone has the advantages of high protein,low fat and rich polyunsaturated fatty acids.However,wild resources of which have declined dramatically due to overfishing and environmental destruction.In this study,the first transcriptome dataset of N.variciferus was obtained by performing de novo RNA sequencing.Moreover,the morphological characteristics of feeding,mating,breeding and early development were described in detail,which provided theoretical and scientific basis for thet development of full artificial seedling technology.The main findings are as follows:(1)Behavioral research video shows that the feeding of fish by N.variciferus has priority over shellfish and crustaceans,has the characteristics of cluster mating.When laying eggs,the N.variciferus are produced in the form of egg capsules.The egg capsules are white oval,with a maximum diameter of 1.38 mm and an average length of 1.1±0.23 mm.The egg capsules is rough around and smooth in the middle,consisting of a membranous base and a calcareous crown.The number of embryos in the N.variciferus egg capsules is in the range of 16 to 85.At the temperature of 20±2 ? and the salinity of 30±4,March,April,November and December are the peaks spawning of N.variciferus,and less in January and February.In November and December,the number of egg capsules laid is more than 20,000,and in March and April,the number of egg capsules can reach 40,000.The number of egg capsules produced by large-scale snails was significantly different from that of medium-sized and small-sized snails(P<0.05).The difference of the length of the egg capsules between the large and medium specifications was not significant(P>0.05),However,the difference in egg capsules produced by large,medium comparison with small sizes was significant(P<0.05).(2)The process of embryonic and larva development of N.variciferus endured the following stages: zygote,embryo cleavage,blastula,gastrula,trochophore,D-larvae,and finally juvenile.At a temperature of 20 ± 2 ?and a salinity of 30±4,the fertilized egg releases the second polar body at 110 min,then begins to divide.Forming two equal-sized blastomeres stage at 4.5 h.After 6-7 h,the second meridian is split,and the split surface is perpendicular to the first cleavage plane,forming 4-cell stage.When it reaches the eight-cell stage,the embryo reaches the gastrula at 19 h and reaches the membrane after one day.The trochophore larvae developed to the veliger larvae in 5 days.It took 20 days to develop to juvenile.(3)A total of 186,487 unigenes were identified from the mature Female and male glands,with an average length of 344 bp.Potential genes and their functions were annotated by analysis of public databases.Genes encoding gonad development in N.variciferus,including those sex differentiation,gonadal differential gene,as well as other related important genes,are described.In addition,a total of 155,984 SSRs and 333,354 SNPs were selected.The first transcriptomic investigation of N.variciferus may provide comprehensive sequence resources for sea snails study.Additionally,the data generated here will contribute to the identification of biomarkers for sea snail,and may help in understanding the gonadal development. |
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