title: Ovulation-inducing factor: a protein component of llama seminal plasma.
abstract: 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.
authors.affiliation: Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada.
authors.forename: Marcelo H
authors.initials: MH
authors.lastname: Ratto
authors.forename: Wilfredo
authors.initials: W
authors.lastname: Huanca
authors.forename: Gregg P
authors.initials: GP
authors.lastname: Adams
mesh_terms: 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*
chemical_list: D029589:Seminal Plasma Proteins
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