The changes in lipid and fatty acid profiles of devil stinger Inimicus japonicas during the development of embryo and yolk-sac larvae

Abstract

wild-caught broodstocks of devil stinger Inimicus japonicas were induced with LHRH-A3 to spawn and the fertilized eggs were incubated artificially in seawater with salinity 29 at 20 ℃.The lipid compositions and fatty acid profiles of the embryos(blastula stage to tail-bud stage)and yolk-sac larvae[newly hatched,1 day post hatching(DPH),2 DPH,3 DPH(unfed)]were investigated.The results indicated that the total lipid content of devil stinger decreased from 13.85% of the blastula stage embryos to 11.66% of 3 DPH larvae.Polar lipid accounted for 72.20%-75.39% of total lipid during the early development.There was no significant difference in total lipid and polar lipid contents during embryogenesis.The total lipid and polar lipid contents declined significantly during the development of yolk-sac larvae.The neutral lipid content first increased,then decreased significantly during embryogenesis and kept stable during the development of yolk-sac larvae.DHA(22∶ 6n-3),16∶ 0,ARA(20∶ 4n-6),EPA(20∶ 5n-3),18∶ 0 and 18∶ 1n-9 were the dominant fatty acids in total lipid of embryos as well as of yolk-sac larvae.The contents(mg/gDW)of DHA,ARA and EPA in total lipid as well as in polar lipid declined significantly during the early development of the devil stinger.There was sharp declining in contents of DHA and ARA in total lipid as well as in polar lipid when the embryo developed from blastula stage to tail-bud stage.The EPA and DHA contents in neutral lipid first increased,then decreased during the early development and the peak appeared at newly-hatched larvae stage and 2 DPH larvae respectively.The ARA content in neutral lipid increased step by step during the early development.DHA and ARA to EPA,saturated fatty acids(SFAs)and poly-unsaturated fatty acids(PUFAs)to mono-unsaturated fatty acids(MUFAs)as well as N-6 PUFA to N-3PUFA were preferentially utilized in total lipid during the early embryonic development.While EPA to DHA and EPA to ARA in total lipid were preferentially utilized during the later embryogenesis and development of yolk-sac larvae.Among the SFAs,16∶ 0 to 18∶ 0 was preferentially utilized during the whole early development.Among the MUFAs,16∶ 1 to 18∶ 1 was preferentially utilized during the later embryogenesis and development of yolk-sac larvae.It was therefore suggested that DHA,EPA and ARA in polar lipid could be transferred into neutral lipid during the early development of devil stinger.And the preferential utilization of some fatty acids depended on the lipid class and the development stage of the embryo and yolk-sac larvae.