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Nucleosides having an enol ester structure in the sugar portion were synthesized and their reaction with several types of electrophiles were carried out. This furnished a new method for constructing C-C bond at the 3'-position. 相似文献
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Shunsuke Yaguchi Atsuko Yamazaki Wakana Wada Yasutaka Tsuchiya Toshihiko Sato Hideo Shinagawa Yutaro Yamada Junko Yaguchi 《Development, growth & differentiation》2015,57(3):242-250
Sea urchins are model non‐chordate deuterostomes, and studying the nervous system of their embryos can aid in the understanding of the universal mechanisms of neurogenesis. However, despite the long history of sea urchin embryology research, the molecular mechanisms of their neurogenesis have not been well investigated, in part because neurons appear relatively late during embryogenesis. In this study, we used the species Temnopleurus reevesii as a new sea urchin model and investigated the detail of its development and neurogenesis during early embryogenesis. We found that the embryos of T. reevesii were tolerant of high temperatures and could be cultured successfully at 15–30°C during early embryogenesis. At 30°C, the embryos developed rapidly enough that the neurons appeared at just after 24 h. This is faster than the development of other model urchins, such as Hemicentrotus pulcherrimus or Strongylocentrotus purpuratus. In addition, the body of the embryo was highly transparent, allowing the details of the neural network to be easily captured by ordinary epifluorescent and confocal microscopy without any additional treatments. Because of its rapid development and high transparency during embryogenesis, T. reevesii may be a suitable sea urchin model for studying neurogenesis. Moreover, the males and females are easily distinguishable, and the style of early cleavages is intriguingly unusual, suggesting that this sea urchin might be a good candidate for addressing not only neurology but also cell and developmental biology. 相似文献
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Protective Effect of External Ca2+ on Elongation and the Intracellular Concentration of K+ in Intact Mung Bean Roots under High NaCl Stress 总被引:2,自引:0,他引:2
Nakamura Yoshiyuki; Tanaka Karo; Ohta Eiji; Sakata Makoto 《Plant & cell physiology》1990,31(6):815-821
The effects of Ca2+ in the external medium on intact mung beanroots under high NaCl stress were investigated. With increasingexternal concentrations of NaCl, mung bean roots showed suppressionof elongation and a decrease in the intracellular concentrationof K+. Addition of Ca2+ to the external medium alleviated theinhibition of root elongation under the high NaCl stress andmaintained a high intracellular concentration of K+ in the elongatingregion of the roots. This counter effect of Ca2+ against theNaCl stress on roots was correlated with the ratio of [Ca2+]/[Na+]2in the external medium. A value above 5.0 ? 104 mM1resulted in almost complete recovery of root elongation undervarious high concentrations of NaCl. Root elongation for 24h under NaCl stress was correlated with the extent to whichthe intracellular concentration of K+ was in excess of 10 mM.Maintenance of an adequate concentration of K+ in root cellsis essential for root elongation under salt stress. These findingsindicate that Ca2+ prevents the leakage of intracellular K+and thereby supports the elongation of roots under salt stress. (Received November 13, 1989; Accepted June 5, 1990) 相似文献
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