CHARACTERIZATION OF A NOVEL CDNA OBTAINED THROUGH DIFFERENTIAL-DISPLAY PCR OF PHORBOL ESTER-STIMULATED OVARIAN TISSUE FROM THE BROOK TROUT (SALVELINUS-FONTINALIS)

A cDNA (DRC1, differentially regulated clone 1) was obtained from diff erential display polymerase chain reaction (PCR) of brook trout ovaria n tissue stimulated with phorbol-12-myristate-13-acetate (PMA) and A23 187. Using 5' RACE (rapid amplification of cDNA ends), two full-length clones were obtained from DRC1 that were 425 and 660 base pairs long and contained the same open reading frame. On Northern blots, DRC1 hyb ridized with two ovarian mRNAs of 0.45 and 0.7 kb that were significan tly suppressed in the presence of PMA and/or A23187. The mRNAs were no t observed in ovaries prior to the resumption of meiosis but were pres ent during ovulation and 24 hr after ovulation. Of either trout tissue s tested by Northen blotting, the expression of DRC1-related transcrip ts also was extremely high in the liver, Based on the full-length cDNA s obtained from RACE, these mRNAs presumably encode an 88-amino-acid p rotein (DRTP1, differentially regulated trout protein 1) that is homol ogous to a gene superfamily composed of snake venom neurotoxins, a CD5 9 complement regulatory protein, Ly-6 alloantigens, and a urokinase-ty pe plasminogen activator receptor, To our knowledge, this is the first description of this type of cDNA from a nonmammalian source other tha n snake venom. In view of the sequence homology and tissue expression of DRTP1, a possible function of this protein may be to regulate the c omplement system in trout. (C) 1998 Wiley-Liss, Inc.