Equine fetal genotyping via aspiration of yolk-sac fluid at 22-28 days of gestation.
Abstract: Fetal genotyping has important applications in the horse, but currently necessitates embryo recovery and biopsy. We investigated whether fetal genotyping could be performed on yolk-sac fluid recovered from pregnant mares via transvaginal aspiration. Fluid was collected before Day 30 to provide results before establishment of the endometrial cups (Day 37). Genotyping and assessment of maternal DNA contamination was performed by analyzing histograms of PCR results for 19 loci. In Exp. 1, mares underwent yolk-sac aspiration on Days 22-28 of gestation. Fluid (0.56-1.02 mL) was recovered from five of seven mares. Four of the five mares maintained pregnancy. One pregnancy was electively terminated at Day 75; the other three mares delivered healthy foals. Extraction of DNA from the fluid sample followed by direct PCR allowed the highest rate of determination of fetal alleles. Fetal genotype was correctly determined in three samples, and for 14/19 alleles in one sample. In Exp. 2, we evaluated whether recovery of more fluid (up to 1.6 mL), and fractionation of the sample, would minimize maternal DNA contamination. One of four mares maintained pregnancy. Evaluation at informative loci showed no difference in maternal contamination among fractions. We determined that mares can maintain pregnancy after aspiration of yolk-sac fluid, and that fetal genotype can be accurately determined from the sample obtained. Further work is needed on factors affecting maintenance of pregnancy after the procedure. The ability to access the yolk sac in early pregnancy opens the door to novel potential clinical and research applications.
Copyright © 2019 Elsevier Inc. All rights reserved.
Publication Date: 2019-09-08 PubMed ID: 31574398DOI: 10.1016/j.theriogenology.2019.09.012Google Scholar: Lookup
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Summary
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This research explores a new method for horse fetal genotyping through the aspiration of yolk-sac fluid from pregnant mares between days 22-28 of gestation, circumventing the need for embryo recovery and biopsy, and revealing potential applications for both clinical and research settings.
Methodology and Experiment 1
- The research aimed to determine if horse fetal genotyping could be successfully conducted through analyzing yolk-sac fluid recovered from pregnant mares.
- This process involved transvaginal aspiration of fluid before Day 30 of gestation, a deadline set to get results prior to the development of endometrial cups on Day 37.
- Genetic analysis and inspection for maternal DNA contamination was carried out by evaluating PCR (Polymerase Chain Reaction) results for 19 loci.
- In the first experiment, yolk-sac aspiration was performed on mares during Days 22-28 of gestation.
- Out of seven mares, fluid was successfully obtained from five, with quantities ranging from 0.56 to 1.02 millilitres. Four of these five mares proceeded with their pregnancies.
- By performing direct PCR on the DNA extracted from the fluid sample, fetal genotypes were successfully identified in three samples; in a fourth, 14 out of 19 alleles were correctly determined.
Experiment 2 and Findings
- In the second experiment, an attempt was made to recover more fluid (up to 1.6 millilitres) and to divide the sample, to check if this would reduce maternal DNA contamination.
- One out of four mares managed to sustain pregnancy in these conditions.
- The evaluation revealed no significant difference in maternal contamination across the different sample fractions.
- These results suggest that mares can maintain a pregnancy following yolk-sac fluid aspiration, and fetal genotype can be accurately identified from such samples.
- Further research is needed to understand the factors influencing the maintenance of pregnancy post-procedure.
Implications
- The success of this novel approach broadens vistas for potential clinical applications and research into horse gestation and genetics.
- This technique could possibly replace more invasive procedures like embryo recovery and biopsy currently used for fetal genotyping in horses.
Cite This Article
APA
Ripley AM, Penedo MCT, Grahn RA, Martinez de Andino EV, Walbornn SR, Serafini R, Love CC, Hinrichs K.
(2019).
Equine fetal genotyping via aspiration of yolk-sac fluid at 22-28 days of gestation.
Theriogenology, 142, 34-40.
https://doi.org/10.1016/j.theriogenology.2019.09.012 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA.
- Veterinary Genetics Laboratory, University of California, Davis, CA, USA.
- Veterinary Genetics Laboratory, University of California, Davis, CA, USA.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA; Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA. Electronic address: khinrichs@cvm.tamu.edu.
MeSH Terms
- Animals
- Embryo, Mammalian
- Female
- Genotype
- Horses / genetics
- Pregnancy
- Yolk Sac
Citations
This article has been cited 1 times.- Aboelmaaty AM, Mohamed RS, Hussein HA, Mohamed RH. Fetal gender prediction by monitoring circulating steroid hormones and some biochemical parameters in maternal dromedary camels. Trop Anim Health Prod 2024 Jun 29;56(6):191.
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