Plasma yolk precursor dynamics during egg production by female greater scaup (Aythya marila): Characterization and indices of reproductive state.
We characterized dynamics of the plasma yolk precursors vitellogenin (VTG), very-low-density lipoprotein (total VLDL-TG), and VLDL particle size distribution during egg production by female greater scaup (order: Anseriformes, Aythya marila). We also evaluated VTG and total VLDL-TG as physiological indices of reproductive state. Mean (+/-1 SE) plasma concentrations of VTG and total VLDL-TG for females with nondeveloped ovaries were 0.58 +/- 0.05 microg Zn mL(-1) and 3.75 +/- 0.29 mmol TG L(-1), respectively. Yolk precursor concentrations increased rapidly to maximum levels in association with small increases in ovary mass during rapid follicle growth. Mean concentrations of VTG and total VLDL-TG for females with a full ovarian follicle hierarchy were 3.38 +/- 0.40 microg Zn mL(-1) and 7.31 +/- 2.56 mmol TG L(-1), respectively. Concentrations of VTG and total VLDL remained elevated throughout the laying cycle and decreased markedly by 3 d into incubation. Individual reproductive state (non-egg producing vs. egg producing) was more accurately identified by plasma profiles of VTG (90%) than by those of total VLDL-TG (74%). Greater scaup VLDL particle sizes during egg production were within the range for predicted yolk-targeted VLDL size (25-44 nm). We conclude that plasma profiles of VTG and total VLDL-TG can be used as nonlethal, physiological indices of reproductive state in greater scaup and should be of great utility to a variety of evolutionary, ecological, and applied conservation studies of reproduction in waterfowl.
Gorman
Kristen B
KB
Centre for Wildlife Ecology, Simon Fraser University, Burnaby, British Columbia, Canada. kgorman@alumni.sfu.ca
Esler
Daniel
D
Walzem
Rosemary L
RL
Williams
Tony D
TD
D000818:Animals; D046090:Anseriformes / Q000378:metabolism / Q000502:physiology*; D004530:Egg Yolk / Q000378:metabolism; D005260:Female; D008079:Lipoproteins, VLDL / Q000097:blood / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism / Q000502:physiology*; D010063:Ovum / Q000378:metabolism / Q000502:physiology*; D010316:Particle Size; D012621:Seasons; D014280:Triglycerides / Q000097:blood / Q000378:metabolism; D014819:Vitellogenins / Q000097:blood / Q000378:metabolism*
D008079:Lipoproteins, VLDL; D014280:Triglycerides; D014819:Vitellogenins