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Protective effects of melatonin on oocyte competence in vitro

Grant number: 14/06885-7
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): August 11, 2014
Effective date (End): January 13, 2015
Field of knowledge:Agronomical Sciences - Veterinary Medicine - Animal Reproduction
Principal researcher:Gisele Zoccal Mingoti
Grantee:Nathália Alves de Souza Rocha Frigoni
Supervisor abroad: Peter J. Hansen
Home Institution: Faculdade de Medicina Veterinária (FMVA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil
Research place: University of Florida, Gainesville (UF), United States  
Associated to the scholarship:12/10083-8 - Strategies for minimizing oxidative stress in in vitro production system of bovine embryos destined for vitrification, BP.DR


Aiming to reduce the impact of heat stress on the oocyte quality, this study will be conducted with the overall goal to evaluate the effectiveness of melatonin supplementation on bovine oocytes exposed to high temperatures on in vitro maturation. For this purpose, cumulus-oocytes complexes (COCs) will be assigned in a 2 x 6 factorial arrangement experiment with two maturation temperatures (38.5ºC or 40oC) and 6 concentrations of melatonin (0, 0.5, 1.0, 2.0, 5 and 10 nM). COCs will be placed in maturation medium containing various concentrations of melatonin and matured for either 22 h at 38.5ºC in an atmosphere of 5% CO2 (control) or 40ºC for 12 h in an atmosphere of 6% CO2 in humidified air followed by 38.5ºC in an atmosphere of 5% CO2 for 10 h. Matured oocytes will be assessed for levels of reactive oxygen species (ROS), and nuclear and cytoplasmic maturation status. After maturation, COCs will be fertilized and the resultant embryos cultured at 38.5ºC for all treatments. Endpoints will be percent of oocytes that cleave at 42-44 h post-fertilization and percent of oocytes and cleaved embryos that become blastocysts at Day 7 and 8 post-fertilization. The effects of melatonin supplementation on the oocyte competence to be fertilized and support development to the blastocyst stage will be evaluated, and also whether beneficial effects of melatonin on oocyte quality represent prevention of damage caused by heat stress. However, it should be clear that the methods of analysis, research project and work plan can be changed as needed, during the scholarship period. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ORTEGA, M. SOFIA; ROCHA-FRIGONI, NATHALIA A. S.; MINGOTI, GISELE ZOCCAL; ROTH, ZVI; HANSEN, PETER J. Modification of embryonic resistance to heat shock in cattle by melatonin and genetic variation in HSPA1L. JOURNAL OF DAIRY SCIENCE, v. 99, n. 11, p. 9152-9164, NOV 2016. Web of Science Citations: 14.

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