A new phenothiazine structural scaffold as inhibitors of bacterial quorum sensing in Vibrio harveyi

Quorum sensing has attracted much attention due to its involvement in pathologically relevant events such as biofilm formation, virulence factor production, and sporulation. Inhibitors of quorum sensing are important research tools and potential therapeutic agents. In this paper, we describe a phenothiazine structural scaffold as a new type of quorum sensing inhibitors with IC₅₀ values in the single digit micro molar range in Vibrio harveyi.     

Genetic characterization of asymmetric reciprocal hybridization between the flatfishes <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> and <Emphasis Type="Italic">Paralichthys dentatus</Emphasis>

Interspecific reciprocal crosses between the two flatfishes Paralichthys olivaceus and P. dentatus yielded hybrids with different viabilities. Specifically, the hybrids of P. olivaceus female and P. dentatus male (HI) were found to be viable, while the reciprocal hybrids from P. dentatus female and P. olivaceus male (HII) were completely inviable. All the HII individuals showed morphological deformities and died before first feeding. The chromosome analysis showed that HI individuals had the same chromosome number as parents. However, two chromosomes were missing in HII offspring indicating that the latter were aneuploids. Genomic inheritance from the parents to F₁ progeny was also examined by amplified fragment length polymorphism (AFLP) analyses, and the results showed differences between reciprocal hybrids. Almost all AFLP bands (97.71%) observed in parents were passed on to HI individuals. In contrast, only 86.64% of the AFLP bands from parents were scored in HII individuals. Frequency of lost parental bands was thus significantly higher in HII than that in HI and intraspecific crosses, which was probably associated with chromosomal elimination. In addition, higher segregation distortions were found in hybrids than in controls, although these differences were not significant. The present study indicates that chromosomal elimination and loss of AFLP loci occurred in inviable HII individuals, while such genomic changes were not found in viable HI individuals. Possible implications of such difference on genomic changes for asymmetric viability in reciprocal hybrids are discussed.     

Ypsilandrosides C-G, five new spirostanol saponins from Ypsilandra thibetica

A further phytochemical investigation on the whole plants of Ypsilandra thibetica yielded one sapogenin and 12 spirostanol saponins. Five of these are new compounds, designated as ypsilandrosides C-G (2–6). Their structures were determined by detailed spectroscopic analysis, including extensive 1D and 2D NMR data, and by the result of a hydrolytic reaction. Compounds 2–5 were rare steroidal saponins that an apiofuranosyl unit was directly linked at C-3 of the aglycone. Selected spirostanol saponins (2–6, 9) were tested for their cytotoxic activities against K562, SPC-A-1, BGC-823, Eca-109, and AGS cell lines. Compounds 6 and 9 showed moderate inhibitory activity against all five cell lines. The antifungal properties of the new spirostanol saponins (2–6) against Candida albicans were also determined.     

Cloning, expression and characterization of a new agarase-encoding gene from marine Pseudoalteromonas sp.

Τhe β-agarase gene agaA, cloned from a marine bacterium, Pseudoalteromonas sp. CY24, consists of 1,359 nucleotides encoding 453 amino acids in a sequence corresponding to a catalytic domain of glycosyl hydrolase family 16 (GH16) and a carbohydrate-binding module type 13 (CBM13). The recombinant enzyme is an endo-type agarase that hydrolyzes β-1,4-linkages of agarose, yielding neoagarotetraose and neoagarohexaose as the predominant products. In two cleavage patterns, AgaA digested the smallest substrate, neoagarooctaose, into neoagarobiose, neoagarotetraose and neoagarohexaose. Site directed mutation was performed to investigate the differences between AgaA and AgaD of Vibrio sp. PO-303, identifying residues V₁₀₉VTS₁₁₂ as playing a key role in the enzyme reaction.     

Bibliography

Water-soluble polysaccharides isolated from the roots of Panax ginseng C. A. Meyer were completely fractionated into two neutral fractions (WGPN and WGPA-N) and six acidic fractions (WGPA-1-RG, WGPA-2-RG, WGPA-1-HG, WGPA-2-HG, WGPA-3-HG and WGPA-4-HG) by a combination of ethanol precipitation, ion-exchange and gel permeation chromatographies. The analytical results showed that WGPN was a starch-like glucan; WGPA-N was a mixture of starch-like glucan and arabinogalactan; WGPA-1-RG and WGPA-2-RG were composed of major neutral sugars and minor acidic sugars that belong to the type-I rhamnogalacturonan (RG-I)-rich pectins, while fractions WGPA-1-HG to WGPA-4-HG were mainly composed of galacturonic acid (GalA, 62.4–92.1%) and have been identified to be homogalacturonan (HG)-rich pectins with different degrees of methyl-esterification, ranging from 0% to 30%. High performance gel permeation chromatography (HPGPC) showed that the six acidic fractions were homogenous, with molecular weights approximately ranging from 3.5 × 10³ to 1.1 × 10⁵. Lymphocyte proliferation assays showed that both the neutral polysaccharides and acidic polysaccharides were potent B and T cell stimulators.     

PQR转运体基因赋予大肠杆菌BL21百草枯抗性

前期研究中成功地分离了2个对百草枯具有高度抗性的土壤细菌SPQ03和SPQ14.本研究从这两个菌分别克隆了基因PnPQR和OaPQR,二者ORF全长均为1 233 bp,编码410个氨基酸残基,含有11个跨膜区(TMS),属于非典型的主要易化超家族(major facilitator superfamily, MFS).立体结构分析表明,蛋白的N端和C端分别由5个和6个由α-螺旋组成的跨膜区.只有P151L和P154V两个氨基酸不同.将两个基因在大肠杆菌BL21菌株中异源表达,能提高大肠杆菌对百草枯的抗性,但不能提高其对过氧化氢的抗性.     

Novel SNP of the goatprolactin gene (PRL) associated with cashmere traits

Concentrations of the single-chain polypeptide hormone prolactin (PRL) are associated with wool or cashmere traits, and its seasonal changes may determine patterns of enzymatic activity and may affect cashmere fibre growth and moult. So, thePRL gene is a potential candidate gene for cashmere traits in marker-assisted selection (MAS). In this paper, we report a novel missense single-nucleotide polymorphism (SNP) within the goatPRL gene in 1367 individuals by PCR-SSCP (polymerase chain reaction with single-strand conformation polymorphism) analysis and DNA sequencing. The novel X76049:g.576C>A mutation is confirmed byEco24I PCR-RFLP (restriction fragment length polymorphism) analysis and causes a missense codon (Pro176Thr). The frequencies of allele C varied from 0.79 to 0.93 in 9 analysed goat populations. C allele was correlated with higher fibre length (P = 0.014).     

IRSp53和MIM同源结构域IMD相互作用蛋白质的鉴定

IRSp53(胰岛素受体酪氨酸激酶底物)和MIM(肿瘤转移消失蛋白)的同源结构域(IMD结构域)在IR-Sp53/MIM家族调控肌动蛋白动态变化的过程中起重要作用.IMD结构域具有使肌动蛋白纤维成束的活性,与小分子GTPase家族Racl也存在相互作用.然而,IMD结构域是否存在其它相互作用蛋白并不清楚.本研究利用GST pull down技术结合质谱分析从大鼠小脑中筛选IMD结构域的相互作用蛋白,得到了几个候选蛋白.其中,神经发育中下调蛋白NEDD9与IRSp53及MIM在小脑中存在类似的分布,体外实验进一步证明了两者之间的相互作用,暗示NEDD9是一种新的IMD结构域相互作用蛋白质.     

Posttranslational Elevation of Cell Wall Invertase Activity by Silencing Its Inhibitor in Tomato Delays Leaf Senescence and Increases Seed Weight and Fruit Hexose Level

Invertase plays multiple pivotal roles in plant development. Thus, its activity must be tightly regulated in vivo. Emerging evidence suggests that a group of small proteins that inhibit invertase activity in vitro appears to exist in a wide variety of plants. However, little is known regarding their roles in planta. Here, we examined the function of INVINH1, a putative invertase inhibitor, in tomato (Solanum lycopersicum). Expression of a INVINH1:green fluorescent protein fusion revealed its apoplasmic localization. Ectopic overexpression of INVINH1 in Arabidopsis thaliana specifically reduced cell wall invertase activity. By contrast, silencing its expression in tomato significantly increased the activity of cell wall invertase without altering activities of cytoplasmic and vacuolar invertases. Elevation of cell wall invertase activity in RNA interference transgenic tomato led to (1) a prolonged leaf life span involving in a blockage of abscisic acid–induced senescence and (2) an increase in seed weight and fruit hexose level, which is likely achieved through enhanced sucrose hydrolysis in the apoplasm of the fruit vasculature. This assertion is based on (1) coexpression of INVINH1 and a fruit-specific cell wall invertase Lin5 in phloem parenchyma cells of young fruit, including the placenta regions connecting developing seeds; (2) a physical interaction between INVINH1 and Lin5 in vivo; and (3) a symplasmic discontinuity at the interface between placenta and seeds. Together, the results demonstrate that INVINH1 encodes a protein that specifically inhibits the activity of cell wall invertase and regulates leaf senescence and seed and fruit development in tomato by limiting the invertase activity in planta.