Alterações celulares em oócitos e embriões da espécie caprina induzidas pelo estresse térmico nas estações seca e chuvosa

Abstract

This study was divided in three stages and aimed to determine the cellular changes induced by heat stress on nuclear maturation in vitro and induction of cell death by apoptosis in goat oocytes and embryos. The ovaries of goats in the dry season and rainy season were collected in a slaughterhouse and transported to the Laboratory of Biotechnical Reproduction of UFRPE. The first stage, the cumulus oophorus complexes in goat of 12 repetitions were collected by the technique of "slicing" of the follicles from 2 to 6 mm in diameter and selected based on morphology. Divided into Group-1 (recovered) and Group-2 (in vitro matured), 25 oocytes per drop were placed in basic medium maturity (MBM). After collection of oocytes, it was determined the quality of oocytes, the enzyme activity of group II caspases with reagent PhiPhiLux-G1D2 and DNA fragmentation (TUNEL). Group-2, after maturation, were determined the stage of nuclear maturation, enzymes caspases and DNA fragmentation. In the stages of nuclear maturation stages of germinal vesicle, disruption of the germinal vesicle, metaphase I and II showed no significant difference (P > 0.05). There was no significant difference (P > 0.05) in the activity ofenzymes and caspases in DNA fragmentation of oocytes recovered and matured in vitro. The second stage, the cumulus oophorus complexes in goat were submitted to maturation, fertilization and in vitro. The percentage of cleaved oocytes was determined on day 3 (D-3) and the oocytes that developed to the stages of 8-16 cells (D-4), morulae (D-5) and blastocyst (D-8) after fertilization. The quality of blastocysts was assessed with the pigment DAPI and the determination of blastomeric positive for apoptosis by TUNEL assay. Significant difference (P < 0.05) stages of fertilization, cultivation in D-3 and morulae. No significant difference (P > 0.05) phases of maturation, growing on D-4, blastocyst and the TUNEL test. Based on these results, we concluded that the dry and rainy seasons will notinfluence the nuclear maturation in vitro apoptosis of oocytes and embryos and in vitro production of embryos in goats.