A conserved domain of previously unknown function in Gap1 mediates protein-protein interaction and is required for biogenesis of a serine-rich streptococcal adhesin

Fap1-like serine-rich proteins are a new family of bacterial adhesins found in a variety of streptococci and staphylococci that have been implicated in bacterial pathogenesis. A gene cluster encoding glycosyltransferases and accessory Sec components is required for Fap1 glycosylation and biogenesis in Streptococcus parasanguinis. Here we report that the glycosylation-associated protein, Gap1, contributes to glycosylation and biogenesis of Fap1 by interacting with another glycosylation-associated protein, Gap3. Gap1 shares structural homology with glycosyltransferases. The gap1 mutant, like the gap3 mutant, produced an aberrantly glycosylated Fap1 precursor and failed to produce mature Fap1, suggesting that Gap1 and Gap3 might function in concert in the Fap1 glycosylation and biogenesis. Indeed, Gap1 interacted with Gap3 in vitro and in vivo. A Gap1 N-terminal motif, within a highly conserved domain of unknown function (DUF1975) identified in many bacterial glycosyltransferases, was required for the Gap1-Gap3 interaction. Deletion of one, four and nine amino acids within the conserved motif gradually inhibited the Gap1-Gap3 interaction and diminished production of mature Fap1 and concurrently increased production of the Fap1 precursor. Consequently, bacterial adhesion to an in vitro tooth model was also reduced. These data demonstrate that the Gap1-Gap3 interaction is required for Fap1 biogenesis and Fap1-dependent bacterial adhesion.     

Maize growth responses to soil microbes and soil properties after fertilization with different green manures

The use of green manures in agriculture can provide nutrients, affect soil microbial communities, and be a more sustainable management practice. The activities of soil microbes can effect crop growth, but the extent of this effect on yield remains unclear. We investigated soil bacterial communities and soil properties under four different green manure fertilization regimes (Vicia villosa, common vetch, milk vetch, and radish) and determined the effects of these regimes on maize growth. Milk vetch showed the greatest potential for improving crop productivity and increased maize yield by 31.3 %. This change might be related to changes in soil microbes and soil properties. The entire soil bacterial community and physicochemical properties differed significantly among treatments, and there were significant correlations between soil bacteria, soil properties, and maize yield. In particular, abundance of the phyla Acidobacteria and Verrucomicrobia was positively correlated with maize yield, while Proteobacteria and Chloroflexi were negatively correlated with yield. These data suggest that the variation of maize yield was related to differences in soil bacteria. The results also indicate that soil pH, alkali solution nitrogen, and available potassium were the key environmental factors shaping soil bacterial communities and determining maize yields. Both soil properties and soil microbes might be useful as indicators of soil quality and potential crop yield.

     

不同波段电磁辐射致大鼠睾丸支持细胞的损伤效应

为探讨不同波段电磁辐射对大鼠睾丸支持细胞(Sertoli细胞)损伤效应的异同.将原代培养的Sertoli细胞经场强6×104V/m的电磁脉冲(electromagnetic pulse,EMP)、平均功率密度为100mW/cm2的S-波段高功率微波(S-band high power microwave,S-HPM)和...     

ANP/NPRA Inhibits Epithelial-Mesenchymal Transition of Airway by Targeting Smad3 in Asthma

International Journal of Peptide Research and Therapeutics - Atrial natriuretic peptide (ANP) has a protective effect on allergic disorders of airway. It could inhibit transforming growth factor...     

人乳头瘤病毒6b型晚期蛋白L_2免疫反应表位的确定

人乳头瘤病毒（ＨＰＶ）含有２个晚期开放读码框（ＯＲＦ）,Ｌ＿２ＯＲＦ编码的蛋白具有型特异性。本研究用能表达产生完整ＨＰＶ６ｂＬ＿２蛋白的质粒ｐ６ｂＬ＿２ＮＸ,采取核酸外切酶Ⅲ定向连续次级克隆的方法,制备了一系列一端逐渐删切的ＤＮＡ片段,诱生一组从Ｃ端至Ｎ瑞依次减少的Ｌ＿２蛋白与相应血清作免疫印迹实验,最小的仍保持阳性反应的多肽即含有抗原表位,实验结果ＨＰＶ６ｂＬ＿２蛋白的核酸编码区位于５４８１－５５０６之间,其相应氨基酸序列是ＥＰＧＩＮＰＴＱ。     

Inhibition of apoptosis and caspase-3 in vascular smooth muscle cells by plasminogen activator inhibitor type-1

Increased expression of plasminogen activator inhibitor type 1 (PAI-1) is associated with decreased apoptosis of neoplastic cells. We sought to determine whether PAI-1 alters apoptosis in vascular smooth muscle cells (VSMC) and, if so, by what mechanisms. A twofold increase in the expression of PAI-1 was induced in VSMC from transgenic mice with the use of the SM-22alpha gene promoter (SM22-PAI+). Cultured VSMC from SM22-PAI+ mice were more resistant to apoptosis induced by tumor necrosis factor plus phorbol myristate acetate or palmitic acid compared with VSMC from negative control littermates. Both wild type (WT) and a stable active mutant form of PAI-1 (Active) inhibited caspase-3 amidolytic activity in cell lysates while a serpin-defective mutant (Mut) PAI-1 did not. Similarly, both WT and Active PAI-1 decreased amidolytic activity of purified caspase-3, whereas Mut PAI-1 did not. WT but not Mut PAI-1 decreased the cleavage of poly-[ADP-ribose]-polymerase (PARP), the physiological substrate of caspase-3. Noncovalent physical interaction between caspase-3 and PAI-1 was demonstrable with the use of both qualitative and quantitative in vitro binding assays. High affinity binding was eliminated by mutations that block PAI-1 serpin activity. Accordingly, attenuated apoptosis resulting from elevated expression of PAI-1 by VSMC may be attributable, at least in part, to reversible inhibition of caspase-3 by active PAI-1.     

Fully Solution‐Processed TCO‐Free Semitransparent Perovskite Solar Cells for Tandem and Flexible Applications

Semitransparent perovskite solar cells (st‐PSCs) have received remarkable interest in recent years because of their great potential in applications for solar window, tandem solar cells, and flexible photovoltaics. However, all reported st‐PSCs require expensive transparent conducting oxides (TCOs) or metal‐based thin films made by vacuum deposition, which is not cost effective for large‐scale fabrication: the cost of TCOs is estimated to occupy ≈75% of the manufacturing cost of PSCs. To address this critical challenge, this study reports a low‐temperature and vacuum‐free strategy for the fabrication of highly efficient TCO‐free st‐PSCs. The TCO‐free st‐PSC on glass exhibits 13.9% power conversion efficiency (PCE), and the four‐terminal tandem cell made with the st‐PSC top cell and c‐Si bottom cell shows an overall PCE of 19.2%. Due to the low processing temperature, the fabrication of flexible st‐PSCs is demonstrated on polyethylene terephthalate and polyimide, which show excellent stability under repeated bending or even crumbing.     

肝素对成纤维细胞促增殖作用的研究

应用核仁组成区相关嗜银蛋白（ＡｇＮＯＲｓ）染色和抗Ⅲ型胶原以及抗５－溴脱氧尿苷单抗免疫组化技术,观察了肝素对体外培养的ＮＩＨ／３Ｔ３成纤维细胞增殖的影响,发现：（１）肝素能促使成纤维细胞数量增加,如０．１ｍｇ／Ｌ浓度的肝素在培养第３天成纤维细胞数量相当于对照值的１．３倍;（２）对成纤维细胞ＡｇＮＯＲｓ的合成显示出明显的促进作用,如０．２ｍｇ／Ｌ浓度的肝素培养第３天,其ＡｇＮＯＲｓ数量为对照值的２．７倍;（３）进一步分析肝素对成纤维细胞ＤＮＡ和Ⅲ型胶原合成的影响,结果表明,加入０．２ｍｇ／Ｌ肝素培养第３天,Ｓ期成纤维细胞和Ⅲ型胶原阳性细胞数分别为对照值的２．７倍和１．８倍。上述实验结果为探讨肥大细胞分秘的活性介质参与器官纤维化作用的机理进而采取相应的对抗措施提供了依据     

Fluorescence resonance energy transfer between two quantum dots with immunocomplexes of antigen and antibody as a bridge.

In this study, 573 nm quantum dots (QDs)-rabbit IgG-goat anti-rabbit IgG-638 nm QDs immunocomplexes were prepared, utilizing antigen-antibody interaction. 573 nm-emitting QDs were conjugated to antigen (rabbit IgG) and 638 nm-emitting QDs were conjugated to antibody (goat anti-rabbit IgG) via electrostatic/hydrophilic self-assembly, respectively. The mutual affinity of the antigen and antibody brought two kinds of QDs close enough to result in fluorescence resonance energy transfer (FRET) between them; the luminescence emission of 573 nm QDs was quenched, while that of 638 nm QDs was enhanced. The luminescence emission of 573 nm QDs could be recovered when the immunocomplexes were exposed to the unlabelled rabbit IgG antigen. The FRET efficiency (E) and the distance between the donor and the acceptor were calculated.