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        검색결과 48

        41.
        2011.09 서비스 종료(열람 제한)
        In particular, maternal prostacyclin (PGI2) is critical for embryo implantation and the action of PGI2 is not mediated via its G protein-coupled membrane receptor, IP, but its nuclear receptor, peroxisome proliferator-activated receptor δ (PPARδ). Recently, several studies have shown that PGI2 enhances blastocyst development and/or hatching rate in vitro, and subsequently implantation and live birth rates in mice. However, the mechanism by which PGI2 improves preimplantation embryo development in vitro remains unclear. Using molecular, pharmacologic and genetic approaches, we show that PGI2-induced PPARδ activation accelerates blastocyst hatching in mice. mRNAs for PPARδ, RXRs (heterodimeric partners of PPARδ) and PGI2 synthase are temporally induced after zygotic gene activation and their expression reaches maximum levels at the blastocyst stage, suggesting that functional complex of PPARδ can be formed in the blastocyst. Carbaprostacyclin (cPGI, a stable analogue of PGI2) and GW501516 (a PPARδ selective agonist) significantly accelerated blastocyst hatching but did not increase total cell number of cultured blastocysts. Whereas U51605 (a PGIS inhibitor) interfered with blastocyst hatching, GW501516 restored U51605-induced retarded hatching. In contrast to improvement of blastocyst hatching by PPARδ agonists, PPAR antagonists significantly inhibited blastocyst hatching. Furthermore, deletion of PPARδ at early stages of preimplantation mouse embryos caused delay of blastocyst hatching, but did not impair blastocyst development. Taken together, PGI2-induced PPARδ activation accelerates blastocyst hatching in mice.
        47.
        1998.09 KCI 등재 서비스 종료(열람 제한)
        The conductivity test is a measure of electrolytes leakage from plant tissue. The shorter the maturation period after heading was the greater electrical conductivity (EC) of rice seed. The polymer-coated seed was not different in EC compared with non-coated seed. As soaking time of rice seed increased, EC increased gradually. The EC varied from 9.9 to 20.7~mu S cm-1g-l for control plots and from 21.3 to 41.7~mu S cm-1g-l for heat-killed seeds which were produced by autoclaving seeds at 121~circC for 20 minutes. The germination speed (the rate of 5th day) of rice seed was 94% at control plot, 83% at low temperature and 20% at high temperature. Besides, germination percentage was 95% for the control, 92% for the low temperature treatment and 39% for the high temperature treatment. The EC was negatively correlated (r=-0.771** ) with germination percentage at low temperature. Water uptake in seeds of 30, 40, 50 days after heading (DAH) was greater than that of 20 DAH. Plant height of seedlings was 9.84 cm for the control but 4.32 cm for the high temperature treatment, and the tallest for polymer-coated seed. Dry weight of seedlings was 0.841 g for the control and 0.287 g at high temperature. Besides, the polymer-coated seed was heavier than non-coated seed. The number of roots was largest from 40 to 50 DAH and polymer-coated seed, but was decreased from 20 to 30 DAH. The length of roots was 20.52 cm at control plot and 19.89 cm polymer-coated seed but 8.68 cm for the low temperature treatment and 7.28 cm for the high temperature treatment.
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