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Distribution and concentration of maternal progesterone in the yolk of Greater Rhea eggs ( Rhea americana )
Author(s) -
Della Costa Natalia Soledad,
Navarro Joaquín Luis,
Busso Juan Manuel,
Marin Raúl Héctor,
Martella Mónica Beatriz
Publication year - 2017
Publication title -
journal of experimental zoology part a: ecological and integrative physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.834
H-Index - 11
eISSN - 2471-5646
pISSN - 2471-5638
DOI - 10.1002/jez.2073
Subject(s) - yolk , biology , population , follicular phase , steroid , yolk sac , steroid hormone , endocrinology , andrology , medicine , hormone , embryo , ecology , fishery , environmental health
Progesterone is the most concentrated maternal yolk steroid characterized to date in birds; however, no information about it is available in ratite eggs. We collected freshly laid eggs from zoo‐housed Greater Rhea females ( Rhea americana ) bred under similar rearing conditions during two breeding seasons to characterize concentration and distribution of maternal yolk progesterone. After high‐performance liquid chromatography analysis, yolk hormone was measured using a commercial electrochemiluminescence immunoassay. Progesterone concentrations were found to vary significantly among the yolk layers, supporting a follicular origin for this steroid in Greater Rhea eggs. Additionally, highly similar mean absolute yolk progesterone concentrations were detected between 2013 and 2015 breeding seasons (1,332.98 ± 82.59 and 1,313.59 ± 85.19 ng/g, respectively). These values are also comparable to those found in some domestic carinate species. Findings suggest that at population level, when rearing conditions are similar, mean absolute yolk maternal progesterone concentrations also appear bounded. Future research on the factors and mechanisms that regulate progesterone deposition in Greater Rhea eggs is needed to better understand whether its levels depend on different rearing conditions.