In vivo staining of mouse preimplantation embryos with Hoechst 33342

Effect of different parthenogenetic activation methods on the developmental competence of in vitro matured porcine oocytes

The aim of this study was to investigate the effect of electrical pulse, ethanol, and ionomycin combined with cycloheximide (CHX), cytochalasin B (CB), and 6-dimethylaminopurine (6-DMAP) on parthenogenetic developmental competence of in vitro matured porcine oocytes. In experiment 1, oocytes were treated with direct current electrical pulse (DC pulse) and then incubated in the NCSU-23 medium supplemented with CHX, 6-DMAP, CB + CHX, and CB + 6-DMAP for 6 h, respectively. The rate of blastocyst development in DC pulse + CB + 6-DMAP group was significantly higher than those in other groups (42.4% vs 23.9% approximately 35.8%; P < 0.05); however, there were no differences in both of the cleavage rate and the cell number of blastocysts among four groups. In experiment 2, oocytes were treated with NCSU-23 medium containing 20 muM ionomycin for 40 min and then incubated in the NCSU-23 medium supplemented with CHX, 6-DMAP, CB + CHX and CB + 6-DMAP for 6 h, respectively. The rates of cleavage and blastocyst development in ionomycin + 6-DMAP group were higher than those obtained in other groups (66.2% vs 46.3% approximately 57.3%; 22.3% vs 7.4% approximately 16.1%; P < 0.05). In experiment 3, the activation effects of ethanol combined with 6-DMAP, CHX, CB + 6-DMAP and CB + CHX were investigated. The rates of cleavage and blastocyst development in ethanol + CB + 6-DMAP group were significantly higher than those in other groups (55.5% vs 42% approximately 46.2%; 18.0% vs 7.1% approximately 11.9%; P < 0.05). In experiment 4, the optimal activation protocols in each group plus DC pulse + ionomycin + 6-DMAP were compared. The results showed the rates of cleavage in DC pulse + CB + 6-DMAP group and ionomycin + 6-DMAP were higher than those in ethanol + CB + 6-DMAP and DC pulse + ionomycin + 6-DMAP (73.8-74.4% vs 56.5-57.5%; P < 0.05), but the blastocyst development only in DC pulse + CB + 6-DMAP group was significantly higher than that in other groups (34.1% vs 13.4% approximately 22.3%; P < 0.05). Total cell number of blastocysts in the group of DC pulse + ionomycin + 6-DMAP was higher than that in other groups (34.1 vs 25.3-27.2; P < 0.05). In conclusion, DC pulse, ethanol, CB, and 6-DMAP all affected the parthenogenesis of porcine oocytes matured in vitro, but their combination of DC pulse + CB + 6-DMAP showed the best result in both of cleavage and blastocyst development.

Mapping of surrogate markers of cellular components and structures using laser desorption/ionization mass spectrometry

Laser desorption/ionization mass spectrometry (LDI-MS) has been used to assess the potential of using surrogate markers, bound to cellular structures containing nucleic acids, to image or map the position of these structures within biological samples. In this study, organic dyes were used as markers because of their established use in the histochemical marking of nucleic acids, and also because they are amenable to LDI-MS. Eight cationic dyes were tested and all could be desorbed from nucleic acid samples without additional matrix after specifically binding to these molecules. Methylene Blue was the best of these based on its sensitivity to detection by LDI-MS and the fact that it can be washed from the tissue in areas where it was not specifically bound to provide low-intensity background signals. Experiments are reported which characterize the M(+) ion signal obtained from Methylene Blue with regard to sensitivity, reproducibility and possible use for quantitation. This dye was used to map (with a lateral resolution of 25 microm) several nucleic acid-containing samples spotted on prepared surfaces, and to image the location of nucleic acids in two model tissues, retinal vertical sections and thyroid whole mount sections.

Activation of mouse oocytes, fertilization and development of mouse embryos in vitro after staining with trypan blue or fluorescein diacetate

The influence of vital staining with trypan blue or fluorescein diacetate on the fertilization of mouse oocytes and the developmental potential of mouse embryos was assessed. Neither stain induced spontaneous activation in mouse oocytes, nor did they impair the in vitro development and implantation of mouse zygotes, two-cell embryos, stressed morulae or blastocysts. However, fertilization and subsequent development of mouse oocytes have been shown to be reduced by vital staining.

Effects of a DNA-specific fluorochrome, Hoechst 33258, on mouse sperm motility and fertilizing capacity

DNA specific fluorochrome (Hoechst 33342 and 33258) as non-toxic stains, have been widely used to measure cell density and proliferation, detect sperm-egg fusion, and observe the development of pre-implantation embryos. It has been reported that Hoechst 33342 at a concentration of 10 micrograms ml-1 had significant inhibition on embryo cleavage. In this study, we incubated B6D2F1 mouse sperm and eggs with different concentrations of Hoechst 33258, 0, 1.0, 10.0, 20.0, 100 micrograms ml-1. We found that: (1) 100 micrograms ml-1 of H-33258 significantly decreased the sperm motility at 90 min and 4 h. (P less than 0.05), (2) 20 micrograms ml-1 and 100 micrograms ml-1 of Hoechst 33258 significantly inhibited mouse fertilization in vitro (P less than 0.05), and (3) 1.0 micrograms ml-1 and 10.0 micrograms ml-1 Hoechst 33258 had no effect on fertilization rate. But when we pre-incubated sperm at 10 micrograms ml-1 Hoechst 33258 for 90 min, and inseminated oocytes in the medium with same concentration of Hoechst 33258, the embryo cleavage was significantly inhibited.