Ovulation-inducing factor: a protein component of llama seminal plasma.
BACKGROUND
Previously, we documented the presence of ovulation-inducing factor (OIF) in the seminal plasma of llamas and alpacas. The purpose of the study was to define the biochemical characteristics of the molecule(s) in seminal plasma responsible for inducing ovulation.


METHODS
In Experiment 1, llama seminal plasma was centrifuged using filtration devices with nominal molecular mass cut-offs of 30, 10 and 5 kDa. Female llamas (n = 9 per group) were treated i.m. with whole seminal plasma (positive control), phosphate-buffered saline (negative control), or the fraction of seminal plasma equal or higher than 30 kDa, 10 to 30 kDa, 5 to 10 kDa, or < 5 kDa. In Experiment 2, female llamas (n = 7 per group) were given an i.m. dose of seminal plasma treated previously by: 1) enzymatic digestion with proteinase-K, 2) incubation with charcoal-dextran, 3) heating to 65 degrees C, or 4) untreated (control). In Experiment 3, female llamas (n = 10 per group) were given an i.m. dose of pronase-treated or non-treated (control) seminal plasma. In all experiments, llamas were examined by transrectal ultrasonography to detect ovulation and CL formation. Ovulation rate was compared among groups by Fisher's exact test and follicle and CL diameters were compared among groups by analyses of variance or student's t-tests.


RESULTS
In Experiment 1, all llamas in the equal or higher than 30 kDa and positive control groups ovulated (9/9 in each), but none ovulated in the other groups (P < 0.001). In Experiment 2, ovulations were detected in all llamas in each treatment group; i.e., respective treatments of seminal plasma failed to inactivate the ovulation-inducing factor. In Experiment 3, ovulations were detected in 0/10 llamas given pronase-treated seminal plasma and in 9/10 controls (P < 0.01).


CONCLUSIONS
We conclude that ovulation-inducing factor (OIF) in llama seminal plasma is a protein molecule that is resistant to heat and enzymatic digestion with proteinase K, and has a molecular mass of approximately equal or higher than 30 kDa.
Ratto
Marcelo H
MH
Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada.
Huanca
Wilfredo
W
Adams
Gregg P
GP
D000818:Animals; D002161:Camelids, New World / Q000502:physiology*; D048429:Cell Size / Q000187:drug effects; D005591:Chemical Fractionation / Q000379:methods; D005260:Female; D008297:Male; D008970:Molecular Weight; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology; D010062:Ovulation Induction / Q000379:methods*; D029589:Seminal Plasma Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology* / Q000502:physiology*
D029589:Seminal Plasma Proteins
Front Neuroendocrinol. 2000 Jul;21(3):220-62
10882541
Theriogenology. 2006 Sep 15;66(5):1102-6
16630652
J Reprod Fertil. 1995 Nov;105(2):247-52
8568767
J Endocrinol. 1969 Dec;45(4):505-13
5366111
Biol Reprod. 2005 Sep;73(3):452-7
15888733
FEBS Lett. 1986 Mar 3;197(1-2):105-10
3512298
Endocr Rev. 1986 Feb;7(1):95-105
3007081
J Reprod Fertil. 1985 Jul;74(2):335-9
3900379
Anim Reprod Sci. 2006 Feb;91(3-4):299-306
15896931
Theriogenology. 2003 Dec;60(9):1645-56
14580647
Vet Res Commun. 2004 Apr;28(3):235-45
15074769
Fertil Steril. 1985 Apr;43(4):617-20
3886437
Nature. 1970 Aug 15;227(5259):680-5
5432063
J Reprod Fertil. 1985 Jul;74(2):341-6
4045809
Reprod Biol Endocrinol. 2005 Jul 14;3:29
16018817
Anim Reprod Sci. 1999 Jan 8;54(3):203-10
10066107
J Reprod Fertil Suppl. 1975 Apr;(22):165-207
810583
Biol Reprod. 1989 Sep;41(3):551-8
2686763
J Reprod Fertil. 1980 May;59(1):237-41
7190608
Biol Reprod. 1985 Sep;33(2):370-4
3899202
Theriogenology. 2001 Jun 1;55(9):1863-79
11414491
J Reprod Fertil Suppl. 1990;40:117-31
2192032
Biochem J. 1994 Sep 1;302 ( Pt 2):595-600
8093013
J Reprod Fertil. 1970 Jul;22(2):261-7
5464117