title: Molecular characterization of putative yolk processing enzymes and their expression during oogenesis and embryogenesis in rainbow trout (Oncorhynchus mykiss).
abstract: Vitellogenin is the major yolk protein precursor in fish, but little is known about its processing pathway in the oocyte, nor about mobilization of yolk proteins during embryogenesis. In this study we cloned three putative yolk processing enzymes; specifically, cathepsin B and L, and lipoprotein lipase (LPL), from the rainbow trout ovary and determined their patterns of gene expression, together with cathepsin D, during oogenesis and embryogenesis using reverse transcription-polymerase chain reaction. The approximate sizes of both cathepsin B and cathepsin L transcripts were estimated as 1.7-1.8 kilobases by Northern blot analysis. Cathepsin D mRNA and cathepsin L mRNA were expressed constitutively throughout vitellogenesis and embryogenesis, showing the highest levels of expression at around fertilization. Cathepsin B and LPL were expressed exclusively during oogenesis. Quantitatively, expression of cathepsin D mRNA was higher than cathepsin B, cathepsin L, and LPL mRNA throughout the period studied. The different patterns of expression for these genes during oogenesis and embryogenesis signify specific temporal roles in yolk protein processing.
authors.affiliation: School of Biological Sciences, University of Exeter, Exeter EX4 4PS, United Kingdom.
authors.forename: J Y
authors.initials: JY
authors.lastname: Kwon
authors.forename: F
authors.initials: F
authors.lastname: Prat
authors.forename: C
authors.initials: C
authors.lastname: Randall
authors.forename: C R
authors.initials: CR
authors.lastname: Tyler
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002401:Cathepsin B / Q000737:chemistry / Q000235:genetics*; D002402:Cathepsin D / Q000235:genetics; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases; D004530:Egg Yolk / Q000378:metabolism; D005260:Female; D005306:Fertilization; D015870:Gene Expression; D008071:Lipoprotein Lipase / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000196:embryology*; D009866:Oogenesis; D010053:Ovary / Q000737:chemistry; D011498:Protein Precursors / Q000737:chemistry; D012333:RNA, Messenger / Q000032:analysis / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014818:Vitellogenesis
chemical_list: D011498:Protein Precursors; D012333:RNA, Messenger; D008071:Lipoprotein Lipase; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L; D002402:Cathepsin D