Low viability of manipulated or in vitro cultured embryos is caused primarily by the reduced cell number in the implanting blastocysts. In order to investigate the effect of implantation delay on embryo viability and cell number, mouse blastocysts were transferred into oviducts of day 0 pseudopregnant females. This type of transfer improved embryo survival rates, indicating that embryos retarded by in vitro culture restored their viability during 3 days of delayed implantation. Our results showed that even in the cases when the initial cell count was as low as 28.2 0.7 cells per blastocyst (vs. 60.5 f 1.4 cells in the control blastocysts, developed in vivo), implantation delay increased this number to 107.2 2 3.5 cells (control blastocysts had at this stage on average 111.0 3.7 cells). Half-blastocysts, developed from the single blastomeres of the 2-cell embryos or from experimentally produced tetraploids, had around 50 cells after 3 days of implantation delay. This indicates that the start of blastocyst dormancy is triggered during the eighth cell cycle and independent of the absolute cell number or the number of cytokineses. Implantation-delayed blastocysts, developed from the half-embryos with the doubled volume of cytoplasm, had on average 70.5 * 2.4 cells, suggesting that embryo fall into quiescence is also dependent upon the attainment of a definite nucleo-cytoplasmic ratio. We conclude that blastocyst readiness for implantation is determined by two factors: number of cell cycles and nucleo-cytoplasmic ratio.
To study an influence of mouse embryonic fibroblasts (C57Fb) transduced with baculovirus vectors (BVs), encoding genes for murine Ifn-β or human IL21, on survival and proliferation of the malignant mouse melanoma cells (B16) in vitro. Methods. Transduction of cells, construction of BVs, RNA isolation, quantitative PCR. Results. We have shown that the normal C57Fb and B16 tumor cells are sensitive to the anti-proliferative effect of IFNβ. Rapidly proliferating B16 cells were the most sensitive. BV ensured a stable expression of Ifnβ mRNA for 5 days in C57Fb/IFNβ cells. The growth of B16 cells was suppressed upon co-cultivation with C57Fb/IFNβ or C57Fb/IL21 cells. Conclusions. IFNβ and IL-21 synthesized by the mouse embryonic fibroblasts transduced with BVs carrying the Ifnβ or IL-21genes inhibited proliferation of B16 melanoma cells in vitro. K e y w o r d s: mouse embryonic fibroblasts, melanoma cells, interferon β (IFNβ), interleukin-21 (IL-21), baculovirus vector, cell transduction.
The recombinant baculovirus vector with EGFP reporter gene under the control of strong CAG promoter cassette was used for transduction of normal (HEK293) and tumor (HeLa) human cell lines. Dependence of transduction efficiency on the virus dose, time of virus incubation, temperature and cell type is shown. Transient reporter gene expression gradually diminished and was detected in single cells on the 15 th day after transduction.
Институт молекулярной биологии и генетики НАН Украины 252143, Киев, ул. Академика Заболотного, 150 Подобраны наиболее благоприятные условия гормональной стимуляции самок мышей инбредных линий ICR, СВЛ/Lac, C57BI/6J. Определен спектр оптимальных концентраций гормонов для каждой из исследованных линий мышей. Отработаны условия культивирования зигот различной линейной принадлежности в системе in vitro. Отмечено, что важным моментом, в значительной степени обеспечивающим успех культивирования зигот в системе in vitro, является стадия развития оплодотворенных яйцеклеток, характеризующаяся временем появления и морфологиче скими особенностями мужского и женского пронуклеусов.
Обзор посвящен анализу литературных данных по клонированию млекопитающих. Рассматрива ются проблемы, связанные с достижениями и ограничениями при клонировании млекопитающих: источники донорских ядер, оптимальные фазы клеточного цикла пересаживаемых ядер, методы их трансплантации, эффективность до-и постимплантационного развития клонов, дефекты их развития и связь с модификацией импринтов.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.