RESUMEN
The zona pellucida (ZP) plays an important role in both the fertilization and embryonic development. For the successful handling of early stage blastomeres for differentiation analysis, the production of identical twins or quadruplets, nuclear transfer or gene introduction requires the removal of the ZP (ZPR). Although single use of either acidic Tyrode's solution or pronase are commonly used for ZPR, long-term exposure to these agents can result in the inhibition of development with the collapse of the three-dimensional blastomere structure. Here, we demonstrate the benefits of using a two-step combined ZPR method, which relies upon a customized well-of-well (cWOW) system with smaller well size, on developmental competence and the quality of the zona free (ZF) mouse embryos. We first isolated 2-cell embryos using acid Tyrode's solution and then cultured these embryos using either commercially available or cWOW, which had a smaller microwell size. The rate of blastocyst was significantly increased by use of cWOW when compared to other culture systems. Then we evaluated the use of a two-step ZPR protocol, relying on acid Tyrode's solution and proteinase K, and subsequent culture in the cWOW system. Although acid Tyrode's solution treatment alone reduced ZPR time, blastomere morphology became wrinkled, significant decrease in blastocyst rate associated with increased number of apoptotic cells and increased expression of apoptosis-related genes were observed. Using proteinase K alone increased ZPR time and significantly decreased the blastocyst rate, but did not induce an increase in apoptotic cell number or apoptosis-related gene expression. In contrast, two-step method significantly reduced ZPR time and improved blastocyst rate by increasing the total number of cells in these wells an reducing the number of apoptotic cells in these experiments. These results suggest that the two-step ZPR protocol is beneficial for reducing the toxic effects of zona removal on ZF embryo development and quality when combined with a suitable culture system.
Asunto(s)
Blastocisto/fisiología , Blastómeros/fisiología , Técnicas de Cultivo de Embriones/métodos , Desarrollo Embrionario/fisiología , Zona Pelúcida/fisiología , Animales , Apoptosis/genética , Blastocisto/citología , Blastómeros/citología , Fragmentación del ADN , Endopeptidasa K/metabolismo , Femenino , Etiquetado Corte-Fin in Situ/métodos , Soluciones Isotónicas/química , Masculino , Ratones Endogámicos ICR , Microscopía Fluorescente/métodosRESUMEN
Chemical modification is the most popular and efficacious approach to improve dispersion stability for commercial carbon blacks in organic media. Even though this method has been used successfully in liquid systems, there have been few reports of chemical modification of carbon black in non-liquid-phase systems. In the present work, a simple non-liquid-phase approach to preparing modified carbon black with high dispersibility and stability in polar organic media from an industrial carbon black, N220, is reported. The treatment was carried out in a rheology mixer by blending carbon black with a low-molecular-weight organic compound, 3,9-bis-(1,1-dimethyl-2[beta-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl)-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80), under proper conditions. The modified carbon black had a smaller particle size than the original carbon black, as proven by dynamic light scattering and transmission electron microscopy, and it could be dispersed facilely in acetone to form a stable suspension. Time-of-flight secondary ion mass spectroscopy was used to detect the chemical presence of AO-80 fragments on the surface of the modified carbon black and consequently the modification mechanism.