Isom S Clay, Prather Randall S, Rucker Iii Edmund B
Division of Animal Sciences, University of Missouri-Columbia, Columbia, MO, USA.
Reprod Fertil Dev. 2009;21(7):892-900. doi: 10.1071/RD08268.
Recently, we demonstrated that a 9-h heat shock of 42 degrees C can have marked stimulatory effects on porcine parthenogenetic embryo development if applied immediately after oocyte activation. Developmental discrepancies between heat-shocked (HS) and non-HS embryos were manifest as early as 3 h after activation, suggesting involvement of maturation promoting factor (MPF) and/or mitogen-activated protein kinase (MAPK). Analysis of cdc2 kinase activity showed that MPF inactivation occurred at similar rates in HS and control embryos upon oocyte activation. However, MAPK dephosphorylation was accelerated in HS embryos compared with controls. Okadaic acid, a protein phosphatase inhibitor, maintained MAPK activity at high levels in both non-HS and HS embryos and sensitised HS embryos to the effects of elevated temperatures. No increase in heat shock proteins was observed in pronuclear-stage HS embryos. These data suggest that the acceleration of development observed in HS porcine parthenogenetic embryos is associated with a precocious inactivation of the MAPK signalling cascade. The faster cleavage divisions observed in HS embryos may be linked physiologically to their enhanced developmental potential in vitro.
最近，我们证明，如果在卵母细胞激活后立即施加42摄氏度的9小时热休克，对猪孤雌生殖胚胎发育会有显著的刺激作用。热休克（HS）胚胎和非HS胚胎之间的发育差异早在激活后3小时就已显现，这表明成熟促进因子（MPF）和/或丝裂原活化蛋白激酶（MAPK）参与其中。对cdc2激酶活性的分析表明，卵母细胞激活后，HS胚胎和对照胚胎中MPF失活的速率相似。然而，与对照相比，HS胚胎中MAPK的去磷酸化加速。冈田酸是一种蛋白磷酸酶抑制剂，它在非HS和HS胚胎中均能使MAPK活性维持在高水平，并使HS胚胎对高温影响更加敏感。在原核期HS胚胎中未观察到热休克蛋白增加。这些数据表明，在HS猪孤雌生殖胚胎中观察到的发育加速与MAPK信号级联的过早失活有关。在HS胚胎中观察到的更快的卵裂可能在生理上与其体外增强的发育潜能相关。
