title: Purification and identification of a second form of vitellogenin from ascites of medaka (Oryzias latipes) treated with estrogen.
abstract: Estrogen treatment of medaka leads to accumulation of ascites, in which vitellogenin (Vg) and choriogenins (precursors to vitelline envelope) are abundant. Besides those female-specific proteins, we detected a new component in ascites that cross-reacts with antiserum against egg yolk proteins. We tentatively named it egg yolk-related protein (YRP). YRP was purified from ascites by hydroxylapatite chromatography followed by gel filtration. Purified YRP had a molecular mass of 460 kDa in intact state while 570 kDa for Vg. The molecular weight of purified YRP on SDS-PAGE under both reducing and nonreducing conditions was 130 kDa. YRP was confirmed to be a lipoglycophosphoprotein by staining with Sudan black, periodic acid-Schiff (PAS) and methyl green. Amino acid composition of YRP resembled that of Vg except for a relatively low content of serine. A specific antiserum against YRP was raised in a rabbit. Antiserum against YRP specifically immunostained its antigen but not Vg or choriogenins. YRP was detected as a female-specific protein in serum of breeding medaka. The antiserum also cross-reacted with a band at 29 kDa in egg extracts, which is not immunoreactive to antiserum against Vg. These data show that YRP is a precursor to some egg yolk proteins with differing antigenicity from Vg (Hamazaki et al. '87). We thus conclude that YRP is a second form of medaka Vg and rename YRP as Vg 2 while formerly reported Vg as Vg 1.
authors.affiliation: School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Munetaka
authors.initials: M
authors.lastname: Shimizu
authors.forename: Yumi
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Fukada
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hara
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000918:Antibody Specificity; D001202:Ascitic Fluid / Q000737:chemistry*; D015153:Blotting, Western; D004527:Egg Proteins / Q000737:chemistry / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005779:Immunodiffusion; D008297:Male; D008970:Molecular Weight; D009990:Oryzias / Q000502:physiology*; D014819:Vitellogenins / Q000031:analogs & derivatives* / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D004527:Egg Proteins; D004967:Estrogens; D014819:Vitellogenins