内生真菌和内生细菌接种对雷公藤生长和次生代谢产物积累的影响

为探究内生真菌与内生细菌对雷公藤(Tripterygium wilfordii)的生长和次生代谢产物积累的相互作用,用内生真菌NS33、NS6和内生细菌LG3、LY1单独或跨界联合接种雷公藤,对雷公藤的生长和雷公藤甲素、雷公藤红素合成进行了研究。结果表明,单独或混合培养的菌株具有分泌铁载体、吲哚乙酸(IAA)和溶磷能力,对种子萌发、芽伸长和根系活力有显著促进作用。接种菌株NS33、NS6、NS6-LG3和NS6-LY1均显著促进了雷公藤组培苗的生长。单独或联合接种菌株均能显著提高雷公藤组培苗雷公藤甲素和雷公藤红素的积累,其中NS33-LG3和LG3的作用最显著。菌株NS33与LG3能够协同促进IAA的分泌、小麦幼苗根系活力和雷公藤红素的积累;菌株NS6与LY1协同提高了雷公藤组培苗的高度、质量和雷公藤红素的积累。因此,内生真菌与内生细菌联合接种对雷公藤生长和次生代谢产物积累具有一定的协同效应,显示出实际应用潜力。     

蛋白质-RNA序列结构界面偏好性及用于对接打分统计势的构建

本文对来自PDB (Protein Data Bank)数据库的蛋白质-RNA复合物结构构建了非冗余非核糖体数据库(694个结构),并对此数据库统计了蛋白质和RNA序列及二级结构的界面偏好性.结果发现,蛋白质β折叠、3_(10)-helix和RNA未配对核苷酸,尤其是未配对中空间排列不规整的核苷酸,具有显著的界面偏好性.据此,对二级结构进行归类,建立了考虑序列和二级结构信息的60×12氨基酸-核苷酸成对偏好势,并将其作为打分函数用于蛋白质-RNA对接中近天然结构的筛选.结果表明,该60×12统计势的打分成功率为65.77%,优于考虑蛋白质或RNA二级结构信息的统计势,及我们小组之前在251个结构上构建的60×8~*统计势.该工作有助于加深对蛋白质-RNA特异性识别的理解,可推动复合物结构预测的进展.     

Variability of qualitative and quantitative secondary metabolites traits among wild genetic resources of Lavandula stoechas L.

Lavandula stoechas L. (Lamiaceae) is an attractive shrub native to the Mediterranean regions used for ornamental, melliferous, aromatic and medicinal purposes. Furthermore, this species presents an increasing interest in cosmetics, perfumery and pharmaceutical industries. The variability of qualitative and quantitative metabolic traits among nine wild germplasms representing the distribution area of this species in Tunisia was undertaken. A total of 45 essential oil components were identified in the aerial parts of the studied germplasms. The main essential oil components were camphor (15.32–50.63%), fenchone (6.57–34.70%), 1,8-cineole (0.05–13.45%) and γ-gurjunene (1.10–12.15%). In addition to the well known chemotypes camphor/fenchone and camphor/1.8-cineole, a new chemotype camphor/γ-gurjunene was detected in Tunisian L. stoechas L. Six phenolic acids (quinic acid, gallic acid, p-coumaric acid, 4,5-di-O-caffeoyquinic acid, salviolinic acid and trans cinnamic acid) and five flavonoids (luteolin-7-o-glucoside, naringin, apegenin-7-o-glucoside, quercetin and kampherol) were identified in the ethanolic extracts. Salviolinic acid (46.30–615.18 μg/g) and luteolin-7-o-glucoside (5.98–38.54 μg/g) were the most abundant phenolic compounds. A high significant phytochemical variability (p ˂ 0.01) in the accumulation of volatile and phenolic secondary metabolites among the studied germplasms was recorded. The conducted multivariate (PCA) and clustering (HCA) analyses revealed different classification pattern for essential oil and phenolic compounds. The detected phytochemical polymorphism among the investigated lavender ecotypes didn't show accordance with bioclimatic and geographical areas which suggests genetic background as the main explaining factor. The detected secondary metabolites polymorphism valorises Tunisian L. stoechas L. genetic resources as valuable plant material in further breeding programs. Moreover, an urgent in situ and ex situ conservation measures are required for these wild germplasms threatened by human over-harvesting practices and the occurring dramatic changes in climatic conditions.     

Incidence and predictors of phantom shocks in implantable cardioverter defibrillator recipients

Background

Implantable cardioverter defibrillators (ICDs) are designed to deliver shocks or antitachycardia pacing (ATP) in the event of ventricular arrhythmias. During follow-up, some ICD recipients experience the sensation of ICD discharge in the absence of an actual discharge (phantom shock). The aim of this study was to evaluate the incidence and predictors of phantom shocks in ICD recipients.

Methods

Medical records of 629 consecutive patients with ischaemic or dilated cardiomyopathy and prior ICD implantation were studied.

Results

With a median follow-up of 35 months, phantom shocks were reported by 5.1 % of ICD recipients (5.7 % in the primary prevention group and 3.7 % for the secondary prevention group; p=NS). In the combined group of primary and secondary prevention, there were no significant predictors of the occurrence of phantom shocks. However, in the primary prevention group, phantom shocks were related to a history of atrial fibrillation (p=0.03) and NYHA class <III (p=0.05). In the secondary prevention group, there were no significant predictors for phantom shocks.

Conclusion

Phantom shocks occur in approximately 5 % of all ICD recipients. In primary prevention patients, a relation with a history of atrial fibrillation and NYHA class <III were significant predictors for the occurrence of phantom shocks. In the secondary prevention patients, no significant predictors were found.     

Implementation of guidelines for implantable cardioverter-defibrillator therapy in clinical practice: Which patients do benefit?

Purpose

Based on multiple large clinical trials conducted over the last decades guidelines for implantable cardioverter-defibrillator (ICD) implantations have been evolving. The increase in primary prophylactic ICD implantations challenges us to be critical towards the indications in certain patient populations.

Methods

We retrospectively collected patient characteristics and rates of appropriate and inappropriate ICD therapy, appropriate and inappropriate ICD shock and mortality of all patients who received an ICD in the University Medical Center Utrecht (UMCU) over the years 2006–2011.

Results

A total of 1075 patients were included in this analysis (74 % male, mean age 61 ± 13 years, left ventricular ejection fraction 30 ± 13 %); 61 % had a primary indication and 58 % had ischaemic heart disease. During a mean follow-up period of 31 ± 17 months, 227 of the patients (21 %) received appropriate ICD therapy (149 (14 %) patients received an appropriate ICD shock). Females, patients with a primary prophylactic indication and patients with non-ischaemic heart disease experienced significantly less ICD therapy. Only a few patients (54, 5 %) received inappropriate ICD therapy; 33 (3 %) patients received an inappropriate ICD shock. Fifty-five patients died within one year after ICD implantation and were therefore, in retrospect, not eligible for ICD implantation.

Conclusion

Our study confirms the benefit of ICD implantation in clinical practice. Nevertheless, certain patients experience less benefit than others. A more patient-tailored risk stratification based on electrophysiological parameters would be lucrative to improve clinical benefit and cost-effectiveness.     

Horizontal gene transfer in eukaryotes: The weak‐link model

The significance of horizontal gene transfer (HGT) in eukaryotic evolution remains controversial. Although many eukaryotic genes are of bacterial origin, they are often interpreted as being derived from mitochondria or plastids. Because of their fixed gene pool and gene loss, however, mitochondria and plastids alone cannot adequately explain the presence of all, or even the majority, of bacterial genes in eukaryotes. Available data indicate that no insurmountable barrier to HGT exists, even in complex multicellular eukaryotes. In addition, the discovery of both recent and ancient HGT events in all major eukaryotic groups suggests that HGT has been a regular occurrence throughout the history of eukaryotic evolution. A model of HGT is proposed that suggests both unicellular and early developmental stages as likely entry points for foreign genes into multicellular eukaryotes.     

Short-term succession of marine microbial fouling communities and the identification of primary and secondary colonizers

Microbial succession during the initial stages of marine biofouling has been rarely studied, especially in the Arabian Gulf. This study was undertaken to follow temporal shifts in biofouling communities in order to identify primary and secondary colonizers. Quantitative analysis revealed a significant increase in total biomass, coverage of macrofoulers, chlorophyll a concentrations, and bacterial counts with time. The relative abundance of the adnate diatoms increased with time, whereas it decreased in the case of the plocon diatoms. Non-metric multidimensional scaling (NMDS) ordination based on MiSeq data placed the bacterial communities in three distinct clusters, depending on the time of sampling. While the relative abundance of Alphaproteobacteria and Flavobacteriia decreased with time, suggesting their role as primary colonizers, the relative abundance of Actinobacteria and Planctomycetia increased with time, suggesting their role as secondary colonizers. Biofouling is a dynamic process that involves temporal quantitative and qualitative shifts in the micro- and macrofouling communities.     

Mechanistic Studies on Metal-pyrophosphate Hydrolysis. Structure of Tetraammine(chloroaquo)cobait(III) dichloride ([CO(NH3)4ClH20]2+•-2Cl−), an Acid Hydrolysis Product of Co(NH3)4HP2O7 and Co(NH3)4PO4

Abstract

The octahedral complex tetraammine(chloroaquo)cobalt(III) dichloride is shown to be the HCl hydrolysis product of both P¹,^2-bidentate tetraammine(pyrophosphato)cobalt(III) [CO(NH₃)₄HP₂0₇ or CoPP] and bidentate tetraammine(phosphato)cobalt(III) [Co(NH₃)₄P0₄or CoP]. The complex crystallizes in the orthorhombic space group Pna2¹ with cell dimensions α=13.033(2)Å, b=6.710(1) Å, and c=10.318(2)Å; the crystal structure was refined to a final disagreement index of 0.033. The average of the four Co-N distances is 1.944±6Å. The Co-Cl distance is 2.257(2)Å and the Co-O(W) distance is 1.971(4)Å. Both protons of the coordinated water molecule are engaged in strong hydrogen bonds to the two nonbonded chloride counterions with 0(W)-C1 distances of 3.087(6)Å and 3.123(6)Å. Each nonbonded chloride is engaged in seven hydrogen bonding interactions resulting from the high ratio of hydrogen bond donors to acceptors in the CoP structure. Cobalt bisphosphate (CoP₂) is the final enzyme hydrolysis product when CoPP is used as substrate in the yeast inorganic pyrophosphatase reaction. The bridge oxygen atom is the site of initial CoPP cleavage both, for HCl catalyzed hydrolysis as well as for enzyme catalyzed hydrolysis.