Gene expression, oocyte nuclear maturation and developmental competence of bovine oocytes and embryos produced after in vivo and in vitro heat shock

Abstract

Three assays were performed. In assay 1, oocytes harvested during the winter months were subjected to kinetic heat shock by stressing the oocytes at 39.5°C (HS1) or at 40.5°C (HS2) for either 6, 12, 18 or 24 h and then matured at control temperature (38.5°C). The nuclear maturation rates (NMR) of all oocytes were recorded after 24 h. In assay 2, oocytes collected year-round maturated, were implanted via in vitro fertilization (IVF) and developed for 9 days. Gene expression analysis was performed on target genes (Cx43, CDH1, DNMT1, HSPA14) with reference to the two housekeeping genes (GAPDH and SDHA) in embryos. Similarly, in assay 3, genetic analysis was performed on the embryos produced from heat-stressed oocytes (from HS1 and HS2). In assay 1, the duration of heat stress resulted in a significant decline in NMR (P < 0.05) with HS1 for maturated oocytes at 86.4 ± 4.3; 65.5 ± 0.7; 51.3 ± 0.9; 38.1 ± 1.9 and 36.3 ± 0.9, for control, 6 h, 12 h, 18 h and 24 h, respectively. For assays 2 and 3, results demonstrated that DNMT1, Cx43 and HSPA14 were down-regulated in the embryos produced in the warm with respect to the cold months (P < 0.05). A constant up- and down-regulation of DNMT1 and HSPA14 genes were observed in both HS-treated samples. Also, an inconsistent pattern of gene expression was observed in Cx43 and CDH1 genes (P < 0.05). Targeted gene expression was aberrant in embryo development, which can provide evidence on early embryo arrest and slowed embryo development.

Heat stress on oocyte or zygote compromises embryo development, impairs interferon tau production and increases reactive oxygen species and oxidative stress in bovine embryos produced in vitro

“…Some studies presented a decrease in cleavage and blastocyst rates; however, the embryos were subjected to immediately change of temperature, without adapting period. (Pavani et al, 2016;Sakatani, Yamanaka, Balboula, Takenouchi, & Takahashi, 2015;Sugiyama, McGowan, Kafi, Phillips, & Young, 2003;Yamanaka et al, 2018). Our results have shown that HS during oocyte maturation, fertilization and/or embryo Trophoblastic cells produce IFNT, which is essential for maternal recognition of pregnancy (Spencer, Johnson, Bazer, & Burghardt, 2004), it is also a good marker for embryonic health (Roberts, Chen, Ezashi, & Walker, 2008).…”

Developmental and molecular responses of buffalo (Bubalus bubalis) cumulus–oocyte complex maturedin vitrounder heat shock conditions

“…Furthermore, heat stress during the summer induced a decrease in oocyte function as a result of a series of cellular alterations affecting nuclear and cytoplasmic compartments of the oocyte (Paula-Lopes et al ., 2012). Therefore many studies have been carried out on bovine oocytes related to heat stress to find the cause behind these catastrophic effects on oocyte competency (Payton et al ., 2004; Ju et al ., 2005; Roth & Hansen, 2005; Paula-Lopes et al ., 2008; Nabenishi et al ., 2012; Maya-Soriano et al ., 2013, Pavani et al ., 2016). To date, the availability of published data on the effect of heat stress on bubaline oocytes and embryos has been very limited (Khairy et al ., 2007; Yadav et al ., 2013, Abdoon et al ., 2014; Ashraf et al ., 2014, 2016; Sadeesh et al ., 2016) and there is no literature available investigating the mechanisms by which heat shock can cause such catastrophic effects on buffalo COCs.…”

Mitochondrial-related consequences of heat stress exposure during bovine oocyte maturation persist in early embryo development

“…Regarding embryos from heat-stressed oocytes, Pavani et al . [ 14 ] reported differential abundance in Cx43, DNMT1, HSPA14.…”