Environmental reprogramming of the expression of protein kinase CK2β subunit in fish

Interleukin-8 (IL-8) is considered as the major polymorphonuclear neutrophils (PMNs) chemoattractant cytokine in lung diseases such as asthma and adult respiratory distress syndrome (ARDS). However, controversial results were obtained regarding the involvement of IL-8 in the pathogenesis of pneumonia. This study examines the role of IL-8 in the recruitment and activation of PMNs in the lung of pneumonia patients. The interesting aspect of this study is that it is a site- specific analysis of the infected and uninfected lungs of the same patient. The level of IL-8 mRNA, protein and myeloperoxidase present in the cells of the bronchioalveolar lavages (BALs) taken from the areas of known pneumonic consolidations on chest X-ray (infected lung) are compared with the BALs obtained from areas of no obvious infiltrate (non-infected lung). The results obtained from the infected and non-infected lungs of pneumonic patients were further compared with that of a control group of non-smoking patients. The level of IL-8 mRNA and protein were determined by RT-PCR and ELISA respectively. There was a significant increase in the level of IL-8 mRNA in the infected lung as compared to its level in the non-infected lung (p < 0.001). In correlation with the increase in mRNA, IL-8 protein concentrations in BAL fluids from the infected lung were 6 fold higher than those taken from the non-infected lung (p < 0.0001). This pattern was also consistent with MPO activity in the BALs (4.5 fold more MPO activity in the infected lung as compared to that of the non-infected lung), indicating that IL-8 is directly implicated in neutrophil accumulation that follows acute respiratory infection. The results of the present study, therefore, indicate the involvement of IL-8 in the pathogenesis of pneumonia.     

胆固醇7,8位脱氢酶的表达及催化活性研究

果蝇的neverland基因是胆固醇7,8位脱氢的重要酶基因。为了探究其在胆固醇脱氢反应中的催化机制,将neverland分别克隆至表达载体p IEx-6及p XY212,再转染导入S2细胞并电转化到S.cerevisiae W303-1A中表达。Western blot结果证实NVD蛋白在重组S2细胞及S.cerevisiae W303-1A中实现了表达。胆固醇转化实验经HPLC分析发现,重组S2细胞可以将胆固醇转化为7-脱氢胆固醇,而重组S.cerevisiae W303-1A并不能实现胆固醇的7,8位脱氢。此外,在重组S.cerevisiae W303-1A和S2细胞的破碎液共同转化胆固醇及NVD体外转化实验中也未发现产物7-脱氢胆固醇的生成。实验结果显示,neverland基因在S2细胞中具有生物活性而在S.cerevisiae中没有生物活性,表明它在胆固醇脱氢时需要其它的伴侣蛋白协助,实验结果为进一步研究其催化机制提供了理论基础。     

亲环素AtCYP1 RNA干涉载体的构建及对拟南芥发育的影响

根据拟南芥AtCYP1基因序列设计特异引物,以拟南芥总DNA为模板,扩增AtCYP1基因中344 bp转录本,插入表达载体PTCK303,构建目的基因RNA干扰载体Ubi::AtCYP1i。利用改良的农杆菌浸染技术获得拟南芥RNAi转基因株系,RT-PCR分析结果表明转基因株系中AtCYP1基因的表达量低于野生型,表型观察结果表明RNAi转基因纯合株系抽苔时间比野生型晚3.32 d,抽苔叶片数较野生型多2.49片,其开花时间、结出第一个种荚的时间、株高等方面也与野生型存在明显差异。此结果说明AtCYP1可能参与了拟南芥的早花发育过程,为进一步研究其在植物生长发育中的功能奠定了基础。     

A Novel Mechanism for Binding of Galactose-terminated Glycans by the C-type Carbohydrate Recognition Domain in Blood Dendritic Cell Antigen 2

Blood dendritic cell antigen 2 (BDCA-2; also designated CLEC4C or CD303) is uniquely expressed on plasmacytoid dendritic cells. Stimulation of BDCA-2 with antibodies leads to an anti-inflammatory response in these cells, but the natural ligands for the receptor are not known. The C-type carbohydrate recognition domain in the extracellular portion of BDCA-2 contains a signature motif typical of C-type animal lectins that bind mannose, glucose, or GlcNAc, yet it has been reported that BDCA-2 binds selectively to galactose-terminated, biantennary N-linked glycans. A combination of glycan array analysis and binding competition studies with monosaccharides and natural and synthetic oligosaccharides have been used to define the binding epitope for BDCA-2 as the trisaccharide Galβ1–3/4GlcNAcβ1–2Man. X-ray crystallography and mutagenesis studies show that mannose is ligated to the conserved Ca²⁺ in the primary binding site that is characteristic of C-type carbohydrate recognition domains, and the GlcNAc and galactose residues make additional interactions in a wide, shallow groove adjacent to the primary binding site. As predicted from these studies, BDCA-2 binds to IgG, which bears galactose-terminated glycans that are not commonly found attached to other serum glycoproteins. Thus, BDCA-2 has the potential to serve as a previously unrecognized immunoglobulin Fc receptor.     

Intact B-cell activity is essential for complete expression of experimental allergic encephalomyelitis in Lewis rats

The mechanisms of the inhibitory effect of the serum thymic factor (FTS) on allograft immunity have been studied on both cellular and humoral immune responses of skin allografted mice. FTS-induced suppression of allogeneic skin graft rejection was correlated with a transient diminution of in vivo alloreactive CTL production in the spleen, whereas the generation of allo-anti-H-2 antibodies was not affected. The involvement of suppressor cells in the effect of FTS was supported by the observation that irradiated spleen cells from FTS-treated recipients (bearing a 9-day allograft) suppressed the in vitro CTL generation.     

Elevated Proton Leak of the Intermediate OH in Cytochrome c Oxidase

The kinetics of the formation and relaxation of transmembrane electric potential (Δψ) during the complete single turnover of CcO was studied in the bovine heart mitochondrial and the aa₃-type Paracoccus denitrificans enzymes incorporated into proteoliposome membrane. The real-time Δψ kinetics was followed by the direct electrometry technique. The prompt oxidation of CcO and formation of the activated, oxidized (O_H) state of the enzyme leaves the enzyme trapped in the open state that provides an internal leak for protons and thus facilitates dissipation of Δψ (τ^app ≤ 0.5-0.8 s). By contrast, when the enzyme in the O_H state is rapidly re-reduced by sequential electron delivery, Δψ dissipates much slower (τ^app > 3 s). In P. denitrificans CcO proteoliposomes the accelerated Δψ dissipation is slowed down by a mutational block of the proton conductance through the D-, but not K-channel. We concluded that in contrast to the other intermediates the O_H state of CcO is vulnerable to the elevated internal proton leak that proceeds via the D-channel.     

Role of specific residues in coenzyme binding, charge-transfer complex formation, and catalysis in Anabaena ferredoxin NADP-reductase

Two transient charge-transfer complexes (CTC) form prior and upon hydride transfer (HT) in the reversible reaction of the FAD-dependent ferredoxin-NADP⁺ reductase (FNR) with NADP⁺/H, FNR_ox-NADPH (CTC-1), and FNR_rd-NADP⁺ (CTC-2). Spectral properties of both CTCs, as well as the corresponding interconversion HT rates, are here reported for several Anabaena FNR site-directed mutants. The need for an adequate initial interaction between the 2′P-AMP portion of NADP⁺/H and FNR that provides subsequent conformational changes leading to CTC formation is further confirmed. Stronger interactions between the isoalloxazine and nicotinamide rings might relate with faster HT processes, but exceptions are found upon distortion of the active centre. Thus, within the analyzed FNR variants, there is no strict correlation between the stability of the transient CTCs formation and the rate of the subsequent HT. Kinetic isotope effects suggest that, while in the WT, vibrational enhanced modulation of the active site contributes to the tunnel probability of HT; complexes of some of the active site mutants with the coenzyme hardly allow the relative movement of isoalloxazine and nicotinamide rings along the HT reaction. The architecture of the WT FNR active site precisely contributes to reduce the stacking probability between the isoalloxazine and nicotinamide rings in the catalytically competent complex, modulating the angle and distance between the N5 of the FAD isoalloxazine and the C4 of the coenzyme nicotinamide to values that ensure efficient HT processes.     

长效油菜素内酯TS303和二氢茉莉酸丙酯协同提高大豆光合能力

研究了长效油菜素内酯TS303、二氢茉莉酸丙酯(PDJ)及二者复配对大豆光合作用的影响及作用机理。试验结果表明：(1)0.01~1 mg·L^-1 TS303浸种促进大豆干物质积累, 以0.1 mg·L^-1的浓度效果最好, TS303对干物质在地上部和根之间的分配没有明显的影响, 1～10 mg·L^-1 PDJ浸种促进干物质积累, 以5 mg·L^-1增幅最大,50和100 mg·L^-1则抑制干物质积累,1～100 mg·L^-1 PDJ均促进同化物质向根系分配;(2)0.1 mg·L^-1 TS303和5 mg·L^-1 PDJ能增加大豆光合叶面积及净光合速率, 增强光合能力, 二者混合使用表现出协同效应;(3)0.1 mg·L^-1 TS303和5 mg·L^-1 PDJ及二者复配增加叶绿素含量和提高PSⅡ的实际光转化效率 (ФPSⅡ), 二者对ФPSⅡ的提高途径不同, TS303增加光合淬灭(qP)而对有效光转化效率(Fv′/Fm′)影响不大, PDJ增加Fv′/Fm而对qP影响不大;(4)0.1 mg·L^-1 TS303和5 mg·L^-1 PDJ及二者复配增加大豆气孔导度、碳酸酐酶活性、RuBPCase含量和活性, 增强CO₂转运和固定能力;(5)0.1 mg·L^-1 TS303和5 mg·L^-1 PDJ及二者复配增加叶片中蔗糖的含量, 提高蔗糖/淀粉比率, 加快同化物质的转运, 增加根中淀粉含量。总体上, TS303在光能转化和CO₂固定方面效果好于PDJ, 而PDJ促进同化物质运出效果好于TS303, 这可能是二者协同提高大豆光合能力的原因。