Synthesis and Characterization of Reversible Chemosensory Polymers: Modulation of Sensitivity through the Attachment of Novel Imidazole Pendants

Three novel electron donor–acceptor conjugated polymers ( P1 – P3 ) bearing various imidazole pendants have been synthesized. Their excellent photophysical and electrochemical properties make them suitable transduction materials for chemosensing applications. Indeed, polymers P1 – P3 have been found to show remarkable sensing capabilities towards H⁺ and Fe²⁺ in semi‐aqueous solutions. Upon titration with H⁺, polymers P1 and P2 showed hypsochromic shifts of their absorptions and photoluminescence (PL) maxima with enhanced fluorescence intensities. However, P3 showed diminished absorption and fluorescence intensities under similar conditions due to static quenching. The anomalous behavior of P3 compared with P1 and P2 has been clarified in terms of electronic distributions through computational analysis. Furthermore, P3 (K_SV=1.03×10⁷) showed a superior sensing ability towards Fe²⁺ compared with P1 (K_SV=2.01×10⁶) and P2 (K_SV=4.12×10⁶) due to its improved molecular wire effect. Correspondingly, the fluorescence lifetime of P3 was greatly decreased (almost 11‐fold) compared to those of polymers P1 (4.6‐fold) and P2 (6.2‐fold) in the presence of Fe²⁺. By means of a fluorescence on‐off‐on approach, chemosensing reversibilities in protonation–deprotonation and metallation–demetallation have been achieved by employing triethylamine (TEA) and the disodium salt of ethylenediaminetetraacetic acid (Na₂‐EDTA)/phenanthroline, respectively, as suitable counter ligands. ¹H NMR titrations have revealed the unique behavior of P3 compared with P1 and P2 . To the best of our knowledge, there have been no previous reports of Fe²⁺ sensors based on single imidazole receptors conjugated to a main‐chain polymer showing such a diverse sensitivity pattern depending on their attached substituents.     

The new sideway of CNTF signal transduction pathway

The action of ciliary neurotrophic factor (CNTF) on intercellular free Ca²⁺ concentrations [Ca²⁺]_i induced by glutamate (Glu) in primary cultured hippocampal neurons were detected with Fura2/AM, a Ca²⁺-sensitive fluorophore, and the morphological influence of G-protein on it was objected. Glu could induce rapid increase of [Ca²⁺]_i in hippocampal neurons. CNTF had no significant action on [Ca²⁺]_i in resting hippocampal neurons. However, after incubation of CNTF for 5 min, the increase of [Ca²⁺]_i in hippocampal neurons rapidly induced by Glu was inhibited. Pretussis toxin (PTX)-sensitive G protein could block the action. These results indicate that a new non-genomic rapid sideway might exist in the upper stream of CNTF signal transduction pathway, which was related to Ca²⁺ signal transduction. Keywords:     

视黄素受体介导的视黄素（retinoids）抗癌作用

对近年来视黄素受体介导视黄素抗癌作用机理的研究进展作一综述,主要有：1）视黄素受体;2）视黄素受体与细胞生长;3）视黄素受体与孤生受体的的相关性;4）视黄素受体对AP-1活性的抑制作用;5）视黄素受体介导的信号转导途径。通过研究,对于探讨视黄素受体的功能、阐明视黄素的抗癌机理、合成更多的受体选择性视黄素具有重要的现实意义。     

Two-Component Signal Transduction Systems in the Cyanobacterium Synechocystis sp. PCC 6803

Introduction Rapid adaptation to environmental challenges is vitally important for bacterial survival and growth. One way in which bacteria control their response to changing environmental conditions is through the mechanism of two-component signal transd…     

植物体细胞胚胎发生的理论研究

把体细胞胚胎发生现象看作开展生物学理论研究的良好模型，介绍了运用细胞生物学和分子生物学的原理与技术进行研究的成果，特别是体细胞胚胎发生相关基因的研究进展。     

LDH参与的机械-光信号转换体系的吸收光谱研究

用紫外-可见分光光度法研究了乳酸脱氢酶(LDH)参与的,以NADH与DPIP.,O₂为主体的机械-光信号振荡转换体系。LDH的酶催化作用使此振荡体系的信号转换效率大大提高,在无乳酸情况下,当DPIP.和NADH的摩尔比为1∶4.5时的平均循环周期由108 min缩短为34 min;在乳酸存在下,此体系的平均循环周期由108 min缩短为29 min。推测LDH的促进作用主要是通过对NADH的活化实现的,其次是通过酶促乳酸脱氢作用补充体系中的NADH获得的。结果说明,酶的催化作用在某些双底物之一存在的反应情况下,也会明显表现出来。     

Synthesis of caged myo-inositol 1,3,4,5-tetrakisphosphate

The total synthesis of an enantiomerically pure Ins(1,3,4,5)P₄ derivative equipped with a photosensitive nitroveratryl group at the 3-O-phosphate is reported.     

植物微丝骨架研究进展

文章就植物花粉管、保卫细胞中微丝骨架以及微丝骨架与信号转导的一些研究进展作了简要介绍 .