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Molecular characterization of three forms of vitellogenin and their yolk protein products during oocyte growth and maturation in red seabream ( Pagrus major ), a marine teleost spawning pelagic eggs
Author(s) -
Sawaguchi Sayumi,
Kagawa Hirohiko,
Ohkubo Nobuyuki,
Hiramatsu Naoshi,
Sullivan Craig V.,
Matsubara Takahiro
Publication year - 2006
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.20446
Subject(s) - vitellogenin , biology , phosvitin , vitellogenesis , oocyte , yolk , vitellogenins , pagrus major , oogenesis , amino acid , biochemistry , microbiology and biotechnology , embryo , fishery , gene , enzyme , protein kinase a , fish <actinopterygii>
Full‐length cDNAs encoding three forms of vitellogenin (Vg) were obtained from a liver cDNA library of estrogen‐treated red seabream, Pagrus major . Two of the three Vg sequences had high homology with type‐A and ‐B Vgs (VgA and VgB) of other teleosts. The third red seabream Vg was classified as a type‐C or phosvitinless (Pvl) Vg due to its lack of a phosvitin (Pv) domain. Two Vg preparations (610 and 340 kDa) from blood serum of estradiol‐treated fish were biochemically characterized. Analyses of precursor‐product relationships by examination of N‐terminal amino acid sequences verified cleavage of the 610 kDa Vg into a 540 kDa lipovitellin (Lv) and a 32 kDa β′‐component. Each of these yolk preparations comprising both VgA‐ and VgB‐derived polypeptides. The 340 kDa Vg, which was immunologically verified to be a PvlVg, was accumulated by vitellogenic oocytes with no alterations to its native molecular mass. During oocyte maturation, the VgA‐ and VgB‐derived yolk proteins were differentially processed, presumably to generate a pool of free amino acids for oocyte hydration or for allocation of specific types of nutrients, amino acids, and proteins, to the developing embryo. Conversely, the 340 kDa Vg‐derived yolk protein is unlikely to contribute to oocyte hydration or diffusible nutrients since the molecule underwent only minor proteolytic nicking during oogenesis. The present study elucidates for the first time specific functions of three different forms of Vg and their product yolk proteins in a higher taxonomic group of marine teleosts that spawn pelagic eggs. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.