Uninjected Embryos Research Articles

Abnormal development and dye coupling produced by antisense RNA to gap junction protein in mouse preimplantation embryos.

Antisense RNA to the 27/32-kDa rat liver gap junction (GJ) protein was used to explore the role of GJs in preimplantation embryos. When all blastomeres of two- and four-cell embryos were injected with GJ antisense RNA, the percentage of embryos compacted at 60 hr of development was reduced to less than 20%, while 90% of uninjected embryos and 75% of embryos injected with an unrelated RNA were compacted. When most cells of compacted eight-cell embryos were injected with the GJ antisense RNA, 20% of the embryos were decompacted and only 5% had developed to the blastocyst stage at 90 hr, when blastulation had occurred in 90% of the control embryos. When antisense RNA was injected in one blastomere of four-cell embryos, 40% of the embryos presented a large cell that was not included in the compacted embryo at the time of compaction, and an additional 30% of the embryos had two smaller, excluded blastomeres. These excluded cells were identified as the injected cell with a rhodamine-conjugated dextran marker. To assess effects on junctional communication, one blastomere of some embryos was injected with Lucifer yellow, a GJ-penetrating dye, at various times after a blastomere was injected with antisense RNA. The dye was visible in the whole cell mass of control embryos, but it was excluded from a portion of experimental embryos when the delay between the RNA and the Lucifer yellow injections was 1 hr or longer.

Nuclear and cytoplasmic mitotic cycles continue in Drosophila embryos in which DNA synthesis is inhibited with aphidicolin.

We have microinjected aphidicolin, a specific inhibitor of DNA polymerase alpha, into syncytial Drosophila embryos. This treatment inhibits DNA synthesis and, as a consequence, nuclear replication. We demonstrate that under these conditions several cycles of both centrosome replication and cortical budding continue, although the cycles have a longer periodicity than is normally found. As in uninjected embryos, when the cortical buds are present, the embryos have nuclei containing decondensed chromatin surrounded by nuclear membranes as judged by bright annular staining with an anti-lamin antibody. As the buds recede, the unreplicated chromatin condenses and lamin staining becomes weak and diffuse. Thus, both cytoplasmic and nuclear aspects of the mitotic cycle continue following the inhibition of DNA replication in the Drosophila embryo.

The effects of low dosages of trichloroethylene on chick development

This study reports the effects of low dosages of trichloroethylene (TCE) (1–25 μmol/egg) on chick development when embryos were exposed directly to TCE on days 1 and 2 and examined at day 14 of embryogenesis. The results indicate that in terms of embryotoxicity, growth defects and morphological anomalies, the treated embryos differed significantly from the controls. The low doses of TCE tested produced 50% mortalities. Survivors in all instances exhibited these developmental defects: evisceration; Subcutaneous edema; light pigmentation of the epidermis; beak malformation; club foot and patchy feathering. The incidence of these malformations varied depending on the day of exposure to TCE except for embryos treated with 1 μ mol. Irrespective of the day of injection or concentration, the highest proportion of malformations were those of light pigmentation and edema. Neither controls (uninjected embryos, O) nor sham controls (mineral oil injected embryos OMO) exhibited any malformations. Differences in measurements of crown-rump (CR), leg, wing, toe and beak lengths between treated embryos and controls were significant at the P < 0.05 level of confidence. However, there was no significant difference between the weights of livers of treated embryos and controls nor was any pathology noted for the livers. The embryotoxicity of TCE is decribed by comparing the average percentage of deaths caused by all concentrations of TCE injected on both days 1 and 2 of embryogenesis. For TCE injected embryos of this average was 2.5 times higher than the average for sham controls and 6 times higher than for uninjected controls.

On the development of the prevertebral (thoracic) duct in turtles as indicated by a study of injected and uninjected embryos

On the development of the prevertebral (thoracic) duct in turtles as indicated by a study of injected and uninjected embryos