AUTHOR=Zeng Xianyuan , Lyu Liang , Zhao Dousha , Zhong Jinying , Feng Yan , Wan Haifu , Li Chunyang , Zhang Ziping , Wang Yilei 

TITLE=dLp/HDL-BGBP and MTP Cloning and Expression Profiles During Embryonic Development in the Mud Crab Scylla paramamosain

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.717751

DOI=10.3389/fphys.2021.717751

ISSN=1664-042X

ABSTRACT=<p>Lipids are the main energy source for embryonic development in oviparous animals. Prior to the utilization and catabolism, lipids are primarily transported from the yolk sac to embryonic tissues. In the present study, cDNA encoding a circulatory large lipid transfer protein (LLTP) superfamily member, the precursor of large discoidal lipoprotein (dLp) and high-density lipoprotein/β-1,3-glucan-binding protein (HDL-BGBP), named <italic>dLp/HDL-BGBP</italic> of 14,787 bp in length, was cloned from the mud crab <italic>Scylla paramamosain</italic>. <italic>dLp/HDL-BGBP</italic> was predicted to encode a 4,831 amino acids (aa) protein that was the precursor of dLp and HDL-BGBP, which were both detected in hemolymph by liquid chromatography–mass spectrometry (LC-MS/MS) analysis. For the intracellular LLTP, three <italic>microsomal triglyceride transfer protein</italic> (<italic>MTP</italic>) cDNAs of 2,905, 2,897, and 3,088 bp in length were cloned from the mud crab and were predicted to encode MTP-A of 881 aa, MTP-B of 889 aa, and MTP-C of 919 aa, respectively, which were different merely in the N-terminal region and shared an identical sequence of 866 aa. During embryonic development, the expression level of <italic>dLp/HDL-BGBP</italic> consecutively increased from the early appendage formation stage to the eye pigment-formation stage, which indicated that HDL-BGBP is probably the scaffolding protein for yolk lipid. For the <italic>MTP</italic> gene, <italic>MTP-C</italic> accounted for ~70% of <italic>MTP</italic> mRNA from the blastocyst stage to the nauplius stage, as well as the pre-hatching stage; <italic>MTP-C</italic> and <italic>MTP-A</italic> expression levels were comparable from the early appendage formation stage to the late eye pigment-formation stage; <italic>MTP-A</italic> was extremely low in blastocyst and gastrula stages; <italic>MTP-B</italic> was expressed at a relatively low-level throughout embryo development. The variations in the expression profiles among <italic>MTP</italic> transcripts suggested that <italic>MTP</italic> might play roles in the lipid droplet maturation and lipoprotein assembly during embryonic development.</p>