Abstract：
This study aimed to evaluate the effect of chemical gasification and HEPES as alternative systems to pH control during in vitro maturation on bovine oocytes competence. Groups of 20 bovine cumulus oocytes complexes (COCs) were randomly distributed and cultured for 24 h in one of the following experimental groups: (i) chemical reaction (ChRG) system: CO2 generated from sodium bicarbonate and citric acid reaction (ii) culture media TCM-HEPES (HEPES-G); and (iii) control group (CNTG) in conventional incubator. After in vitro maturation (IVM), the COCs were in vitro fertilized (IVF), and in vitro cultivated (IVC) in a conventional incubator. We evaluated oocyte nuclear maturation, cleavage and blastocyst rates, in addition to the relative mRNA expression of BAX, BMP-15, AREG and EREG genes in oocytes and cumulus cells. The proportion of oocytes in metaphase II was higher in CNTG and ChRG (77.57% and 77.06%) than in the HEPES-G (65.32%; p = .0408 and .0492, respectively). The blastocyst production was similar between CNTG and ChRG (26.20% and 28.47%; p = .4232) and lower (p = .001) in the HEPES-G (18.71%). The relative mRNA expression of BAX gene in cumulus cells was significantly higher (p = .0190) in the HEPES-G compared to the CNTG. Additionally, the relative mRNA expression of BMP-15 gene was lower (p = .03) in oocytes from HEPES-G compared to the CNTG. In conclusion, inadequate atmosphere control has a detrimental effect on oocyte maturation. Yet, the use of chemical gasification can be an efficient alternative to bovine COCs cultivation.
摘要：
本研究旨在评估化学气化和HEPES作为体外成熟过程中pH控制的替代系统对牛卵母细胞能力的影响。将20种牛卵丘卵母细胞复合物（COCs）随机分配并在以下实验组之一中培养24h：（i）化学反应（ChRG）系统：碳酸氢钠和柠檬酸反应产生的CO2（ii）培养基TCM-HEPES（HEPES-G）；（iii）常规培养箱中的对照组（CNTG）。体外成熟（IVM）后，COCs进行了体外受精（IVF），并在常规培养箱中进行体外培养(IVC)。我们评估了卵母细胞的核成熟,卵裂和胚泡率，除了BAX的相对mRNA表达，卵母细胞和卵丘细胞中的BMP-15、AREG和EREG基因。CNTG和ChRG中中期II的卵母细胞比例（77.57％和77.06％）高于HEPES-G（65.32％；p=.0408和.0492）。CNTG和ChRG之间的胚泡产生相似（26.20％和28.47％；p=.4232），而HEPES-G（18.71％）更低（p=.001）。与CNTG相比，HEPES-G中卵丘细胞中BAX基因的相对mRNA表达明显更高（p=0.0190）。此外,与CNTG相比，HEPES-G卵母细胞中BMP-15基因的相对mRNA表达较低（p=0.03）。总之,不充分的气氛控制对卵母细胞成熟有不利影响。然而，使用化学气化可以有效替代牛COCs培养。
