微生物在镉污染土壤修复中的应用及其作用机理

土壤中镉（Cd）含量的超标导致了土壤生态系统的恶性发展,微生物作为土壤中的常见组分之一在缓解土壤镉污染中展现出巨大潜力。本文总结了微生物、微生物-植物和微生物-生物炭在镉污染土壤修复中的应用并阐述了相关的作用机理。芽孢杆菌（Bacillus）、不动杆菌（Acinetobacter）、荧光假单胞菌（Pseudomonas fluorescence）、丛枝菌根真菌（arbuscular mycorrhizal fungi,AMF）等微生物可以通过吸附、矿化、沉淀、溶解等方式改变镉的生物有效性,从而达到缓解镉污染的目的。pH值、温度、微生物生物量、镉初始浓度以及时间等对微生物降低镉的生物有效性方面有着显著的影响。假单胞菌、伯克霍尔德菌（Burkholderia）、黄杆菌（flavobacterium）等微生物可以通过促生、活化等作用促进超富集植物对Cd²⁺的吸收。生物炭作为一种土壤改良剂,其独有的理化性质可以作为微生物的庇护所。微生物-生物炭联合使用与单用生物炭相比可以进一步促进镉的残渣态的增加,降低土壤中有效态的比例。     

Comparative Transcriptome Analyses Reveal Genes Related to Spine Development in Cucumber (<i>Cucumis sativus</i>)

Fruit spine is an important quality trait of cucumber. To better understand the molecular basis of cucumber spine development and function, RNA-Seq was performed to identify differentially expressed genes (DEGs) in fruit spines of different development stages, namely, 8 days before anthesis (SpBA8), anthesis (SpA) and 8 days after anthesis (SpAA8). Stage-wise comparisons obtained 2,259 (SpBA8 vs. SpA), 4,551 (SpA vs. SpAA8), and 5,290 (SpBA8 vs. SpAA8) DEGs. All the DEGs were classified into eight expression clusters by trend analysis. Among these DEGs, in addition to the Mict, Tril, CsTTG1, CsMYB6, NS, and Tu genes that have been reported to regulate fruit spine formation, we found that the CsHDG11, CsSCL8, CsSPL8, CsZFP6 and CsZFP8 may also be involved in spine development in cucumber. Our study provides a theoretical basis for further research on molecular mechanisms of spine development in cucumber.     

非编码小RNA对细菌毒力及耐药性的调控作用研究进展

近年来的研究发现,细菌非编码小RNA (small non-coding RNA, sRNA)对其不同生理进程起到了重要的调控作用。随着大量sRNA被发现并鉴定,细菌sRNA的功能被逐步阐明,其可在转录后水平广泛调控细菌的生理代谢、毒力及耐药性等。本文综述了sRNA对细菌毒力和耐药性调控作用的研究进展,对揭示细菌转录后水平毒力及耐药性调控机制具有一定意义。     

pH对生物合成超声分子影像探针气囊充放气的调控

气囊（gas vesicles,GVs）是一种存在于蓝藻及古菌等微生物中调节浮力的类细胞器纳米结构,由蛋白质外壳包裹气体组成。近年来的研究表明,气囊具有作为超声分子影像探针的潜力。然而,气囊的充放气机制并不明确,限制了生物合成超声分子影像探针的保存和气体更换。本研究发现环境pH值是调节气囊充放气的一个重要因素。其不仅可以调节藻细胞内的气囊充放气进而使微囊藻呈现不同的漂浮状态,还可对提纯的气囊充放气进行体外调节,且该调节过程可逆。该机制的阐明为生物合成超声分子影像探针的大规模生产和保存,特别对气囊中的气体进行更换以满足不同的诊疗需求提供了技术支持,助力生物合成超声造影剂在疾病诊疗中的应用。     

Picroside III,an Active Ingredient of Picrorhiza scrophulariiflora,Ameliorates Experimental Colitis by Protecting Intestinal Barrier Integrity

This study aims to explore the protective effects of Picroside III, an active ingredient of Picrorhiza scrophulariiflora, on the intestinal epithelial barrier in tumor necrosis factor-α (TNF-α) induced Caco-2 cells and dextran sulfate sodium (DSS) induced colitis in mice. Results show that Picroside III significantly alleviated clinical signs of colitis including body weight loss, disease activity index increase, colon shortening, and colon tissue damage. It also increased claudin-3, ZO-1 and occludin expressions and decreased claudin-2 expression in the colon tissues of mice with colitis. In vitro, Picroside III also significantly promoted wound healing, decreased the permeability of cell monolayer, upregulated the expressions of claudin-3, ZO-1 and occludin and downregulated the expression of claudin-2 in TNF-α treated Caco-2 cells. Mechanism studies show that Picroside III significantly promoted AMP-activated protein kinase (AMPK) phosphorylation in vitro and in vivo, and blockade with AMPK could significantly attenuate the upregulation of Picroside III in ZO-1 and occludin expressions and the downregulation of claudin-2 expression in TNF-α treated Caco-2 cells. In conclusion, this study demonstrates that Picroside III attenuated DSS-induced colitis by promoting colonic mucosal wound healing and epithelial barrier function recovery via the activation of AMPK.     

Immunogenicity of the Shigella flexneri Serotype Y (SFL124) Vaccine Strain Expressing Cloned Glucosyl Transferase Gene of Converting Bacteriophage SfX

The glucosyl transferase gene (gtr) from bacteriophage phage X (SfX) caused partial conversion of serotype Y (group antigen 3, 4) to X (group antigen 7, 8) when introduced into a candidate vaccine strain of Shigella flexneri serotype Y (SFL124). The gtr gene caused conversion of O-antigens but did not eliminate the adsorption of the corresponding phage SfX. The hybrid strain expressing both group antigens 7, 8 and 3, 4 showed 75% protection when immunized guinea pigs were challenged with a wild-type S. flexneri serotype X strain. No protection was observed against serotype Y challenge, although group antigen 3, 4 was detected in the LPS of the hybrid strain. This suggests the importance of O-antigen immunity in the host defense against shigellosis.     

UPRE-lac Z为报告基因评价酵母UPR响应初步研究 *

目的: 未折叠蛋白质反应UPR是酵母最重要蛋白质质量控制机制之一,研究UPR响应规律有助于优化异源蛋白分泌途径合成和应对酸醇等胁迫因子的细胞自我保护。方法: 选择实验室菌株W303-1A和工业菌株An-a,以UPRE启动子控制下的Lac Z为报告基因,利用CRISPR/Cas9技术构建得到指示菌株W303-1A (leu 2::UPRE-lac Z)和An-a (leu 2::UPRE- lac Z),分别简称WZ和AZ。结果: 生长曲线测定显示WZ和AZ与亲本菌株的生长接近;添加下述试剂孵育4h后测定β-半乳糖苷酶酶活:1μg/ml衣霉素、8%(v/v)乙醇、0.3%(v/v)乙酸、5%(v/v)乙醇+0.1%(v/v)乙酸;菌株AZ的比酶活分别是对照值的8.2、26.4、1.1和7.9倍,而菌株WZ则分别为12.6、2.4、1.0和1.0倍;进一步以YEplac195为载体表达β-葡萄糖苷酶,AZ和WZ转化子在2%纤维二糖中生长24h的β-葡萄糖苷酶酶活值分别为0.35和6.12U/ml,相应的LacZ则分别为对照值的3.1和5.4倍。结论: 两个菌株显示了在抑制物和异源蛋白表达UPR响应和调控能力上的显著差异,为其改造利用提供了方向;研究也为分析抑制物耐受性和异源蛋白表达关键制约因素、优化酵母ER和UPR信号通路的调控奠定了初步方法基础。     

cDNA for the carboxyl-terminal region of a rat intestinal mucin-like peptide.

When subjected to thiol reduction, purified intestinal mucins have been shown to undergo a decrease in molecular mass and to liberate a 118-kDa glycopeptide (Roberton, A. M., Mantle, M., Fahim, R. E. F., Specian, R., Bennick, A., Kawagishi, S., Sherman, P., and Forstner, J. F. (1989) Biochem. J. 261, 637-647). The latter has been called a putative "link" component because it is assumed to be important for disulfide bond-mediated mucin polymerization. Controversy exists as to whether the putative link is an integral mucin component or a separate mucin-associated glycopeptide. In the present study both NH2-terminal and internal amino acid sequences of the 118-kDa glycopeptide of rat intestinal mucin were used to generate opposing oligonucleotide primers for polymerase chain reaction. A specific 1.2-kilobase (kb) product was obtained, from which a 0.5-kb HindIII fragment was used as a probe to screen a lambda ZAP II cDNA library of rat intestine. A 2.6-kb cDNA (designated MLP 2677) was sequenced and revealed an open reading frame of 2.5 kb encoding 837 amino acids. The deduced amino acid sequence showed that the putative link peptide is equivalent to the carboxyl-terminal 689 amino acids of a larger peptide. Northern blots revealed a mRNA size of approximately 9 kb. Computer searches revealed no sequence homology with other proteins, but similarities were seen in the alignment of cysteine residues in the link and in several domains of human von Willebrand factor, as well as cysteine-rich areas of bovine and porcine submaxillary mucins and a frog skin mucin designated FIM-B.1. In keeping with earlier demonstrations of the presence of mannose in the 118-kDa glycopeptide, there were several (13) consensus sequences for attachment of N-linked oligosaccharides within the link domain. Further sequencing of MLP 2677 in a direction 5' to the codon specifying the NH2-terminal proline of the link has revealed a coding region for 148 amino acids, including a unique 75-amino acid domain rich in cysteine and proline, and a region containing 4.5-variable tandem repeats (each 11-12 amino acids) rich in serine, threonine, and proline. The presence of mucin-like tandem repeats suggests that the entire cysteine-rich link peptide represents the carboxyl-terminal region (75.5 kDa) of a mucin-like peptide (MLP). The latter is estimated to have a molecular mass of approximately 300 kDa.