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Curry E, Philpott ME, Wojtusik J, Haffey WD, Wyder MA, Greis KD, Roth TL. Label-Free Quantification (LFQ) of Fecal Proteins for Potential Pregnancy Detection in Polar Bears. Life (Basel) 2022; 12:life12060796. [PMID: 35743827 PMCID: PMC9225558 DOI: 10.3390/life12060796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 11/28/2022] Open
Abstract
Reliable pregnancy diagnostics would be beneficial for monitoring polar bear (Ursus maritimus) populations both in situ and ex situ, but currently there is no method of non-invasive pregnancy detection in this species. Recent reports in several carnivore species described the identification of fecal proteins that may serve as pregnancy biomarkers; however, repeatability has been limited. The objective of the current analysis was to utilize an unbiased, antibody-free, label-free method for the identification and quantification of fecal proteins to determine if differences associated with pregnancy are detectable in polar bears. Protein was extracted from fecal samples (n = 48) obtained from parturient (n = 6) and non-parturient (n = 6) profiles each at four timepoints: pre-breeding season, embryonic diapause, early placental pregnancy, and mid-placental pregnancy. Protein was prepared and analyzed on the Thermo Orbitrap Eclipse nanoLC-MS/MS system. A total of 312 proteins was identified and quantified; however, coefficients of variation (CV) were high for both abundance ratio variability (384.8 ± 61.0% SEM) and within group variability (86.8 ± 1.5%). Results of this study suggest that the inconsistencies in specific protein concentrations revealed previously by antibody-based assays may not be due to that methodology’s limitations, but rather, are reflective of true variation that exists among samples.
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Affiliation(s)
- Erin Curry
- Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, Cincinnati, OH 45220, USA; (M.E.P.); (J.W.); (T.L.R.)
- Correspondence:
| | - Megan E. Philpott
- Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, Cincinnati, OH 45220, USA; (M.E.P.); (J.W.); (T.L.R.)
| | - Jessye Wojtusik
- Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, Cincinnati, OH 45220, USA; (M.E.P.); (J.W.); (T.L.R.)
- Department of Reproductive Sciences, Omaha’s Henry Doorly Zoo and Aquarium, Omaha, NE 68107, USA
| | - Wendy D. Haffey
- UC Proteomics Laboratory, Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (W.D.H.); (M.A.W.); (K.D.G.)
| | - Michael A. Wyder
- UC Proteomics Laboratory, Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (W.D.H.); (M.A.W.); (K.D.G.)
| | - Kenneth D. Greis
- UC Proteomics Laboratory, Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (W.D.H.); (M.A.W.); (K.D.G.)
| | - Terri L. Roth
- Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, Cincinnati, OH 45220, USA; (M.E.P.); (J.W.); (T.L.R.)
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