Recipient Organization
CLEMSON UNIVERSITY
(N/A)
CLEMSON,SC 29634
Performing Department
Animal & Veterinary Sciences
Non Technical Summary
Successful reproduction of livestock is critical for the economic livelihood of farmers and affects the consumer cost of meat and other animal products [1]. In vitro-production of embryos is one of many assisted reproductive technologies having a positive impact on cattle production systems. In vitro-production of embryos has several advantages over the recovery of in vivo-derived embryos, but in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC) procedures still have room for improvement. In the cattle system, in vitro production of blastocyst (the embryonic developmental stage that is commonly transferred into a recipient cow to obtain a pregnancy) has plateaued at around 40%; however, the in vivo embryonic development rate is in the range of 85 to 95%. Among the many steps for in vitro embryo production, oocyte cytoplasmic maturation is a critical factor determining the success of subsequent embryo development (oocyte is the ovum or "egg") [2-5]. In this project, we propose to use light stimulation to enhance oocyte cytoplasmic maturation. Based on reports in other cells and tissues [6], the light wavelength, time, and frequency of exposure may have different effects on cells, ranging from null, to stimulating, to detrimental. We will test different light protocols during oocyte maturation, and measure the subsequent changes in blastocyst production. A significant increase in blastocyst production will make the in vitro production system more efficient, reducing costs for cattle producers and their customers. In the process, we will also increase our understanding of the basic physiology of the oocyte, the maturation process and the effects of photostimulation in general.1. USDA/NIFA Animal Reproduction Program home page: https://nifa.usda.gov/program/animal-reproduction2. Farin PW, Slenning BD, Britt JH. Estimates of pregnancy outcomes based on selection of bovine embryos produced in vivo or in vitro. Theriogenology 1999; 52:659-670.3. Pomar FJ, Teerds KJ, Kidson A, Colenbrander B, Tharasanit T, Aguilar B, Roelen BA. Differences in the incidence of apoptosis between in vivo and in vitro produced blastocysts of farm animal species: a comparative study. Theriogenology 2005; 63:2254-2268.4. Rizos D, Clemente M, Bermejo-Alvarez P, de La Fuente J, Lonergan P, Gutierrez-Adan A. Consequences of in vitro culture conditions on embryo development and quality. Reproduction in Domestic Animals 2008; 43 Suppl 4:44-50.5. Rizos D, Fair T, Papadopoulos S, Boland MP, Lonergan P. Developmental, qualitative, and ultrastructural differences between ovine and bovine embryos produced in vivo or in vitro. Molecular Reproduction and Development 2002; 62:320-327.6. Karu, TI, Mitochondrial signaling in mammalian cells activated by red and near-IR radiation. Photochemistry and Photobiology 2008; 84:1091-1099
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Understand the biology of gamete development, fertilization and embryogenesis including the underlying cellular and molecular mechanisms.
Refine methods to produce animals by genetic engineering or genome editing for the improvement of livestock production efficiency and development of human biomedical models.
Project Methods
Abattoir-derived ovaries will be used. Follicles 2-6 mm in diameter will be aspirated. Oocytes with compact cumulus and homogeneous cytoplasm will be selected; oocytes/well will be placed in in vitro maturation medium (IVM) and incubated at 38.5 ºC in 5% CO2 in air with high humidity. Different photostimulation regimes will be used to affect the oocyte metabolic state, aiming to enhance cytoplasmic maturation rates and subsequent embryonic development. Control (no light exposure) and treatment oocytes will be fertilized with different bulls to address sire to sire variability. Standard in vitro embryo production techniques will follow (separation of cumulus cells and in vitro culture for up to 8 days, changing media every 48 h). Each experiment will be repeated 4 to 6 times. Evaluation: Cleavage and blastocyst rates will be compared between control and treatment groups. Possible bull interactions will be included in the statistical analysis.