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Oocyte responses to heat stress

Grant number: 17/13082-6
Support type:Scholarships in Brazil - Master
Effective date (Start): October 01, 2017
Effective date (End): February 28, 2019
Field of knowledge:Agronomical Sciences - Veterinary Medicine
Principal Investigator:Fabíola Freitas de Paula Lopes
Grantee:Lais Barbosa Latorraca
Home Institution: Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF). Universidade Federal de São Paulo (UNIFESP). Campus Diadema. Diadema , SP, Brazil

Abstract

The dairy cattle of tropical and subtropical countries, such as Brazil, are subject to adverse environmental conditions, like heat stress. The negative effect of heat stress on fertility is multifactorial affecting follicular growth, oocyte and pre-implantation embryonic development, among others. Special attention has been given to the oocyte due to the high susceptibility of this cell to elevated temperature, reducing fertilization capacity and subsequent embryonic development. The effects of heat stress on cattle reproduction are well characterized, but little has been elucidated on the cellular response to these conditions. A new line of research has the endoplasmic reticulum (ER) as the target of study, since many of the pathways activated by cellular stress converge their response to ER, activating the unfolded protein response (UPR) in order to restore cellular homeostasis. The hypothesis of this project is that exposure of cumulus-oocyte complexes (COCs) to heat shock during in vitro maturation (IVM) compromises the function of ER and oocyte developmental competence. To test this hypothesis, experiments will be carried out to determine whether heat shock induces ER stress and reorganization as well as oocyte protein synthesis. In addition, this project aims to determine the role of oocyte ER stress on fertilization and embryonic developmental kinetics of bovine oocytes submitted to heat shock during IVM.Key words: heat shock, endoplasmic reticulum stress, bovine oocyte.