Mikrobielle Ökologie N-Acyl-L-Homoserinlacton-produzierender Bakterien in der Rhizosphäre von Tomatenpflanzen

N-Acylhomoserinlactones (AHL) are signalling molecules in gram-negative bacteria, which regulate, in a cell density dependent way, important interactive functions. This phenomenon is known as quorum-sensing. This work characterised the microbial ecology of the autoinducer (AHL) producing bacteria Serratia liquefaciens MG1 and Pseudomonas putida IsoF in the rhizosphere of tomato plants. Gfp- and rfp-tagged strains of the AHL producing wiltypes S. liquefaciens MG1 and P. putida IsoF were compared with its AHL-negative mutants, which were unable to produce AHL. Two kinds of plants cultivating systems were used: a defined axenic system and a complex soil system. The characterisation of the root colonisation behaviour was performed using confocal laserscanning microscopy (CLSM) and cell counting of bacteria. Fluorescence in situ hybridisation (FISH) and terminal restrictions fragment length polymorphism (t-RFLP)-techniques were used to examinate shifts of the bacterial population in the rhizosphere on tomato plants. The effective in situ production and spreading of AHL on tomato roots was demonstrated with P. putida IsoF using an AHL-sensor strain P. putida F117 pKR-C12. AHL was produced in effective concentrations in the rhizosphere of tomato plants and influenced the bacterial rhizosphere population. However, the AHL-production had no influence on the colonization behaviour of the AHL-producing strains S. liquefaciens MG1 and P. putida IsoF.N-Acyl-L-Homoserinlactone (AHL) sind bakterielle Signalstoffe, welche in Gram-negativen Bakterien Zelldichte-abhängig wichtige interaktive Funktionen steuern. Dieses Verhalten ist als "quorum-sensing" bekannt. In der vorliegenden Arbeit wurde der Einfluß von AHL-Produktion auf das Siedlungsverhalten der Rhizosphärenbakterien Serratia liquefaciens und Pseudomonas putida auf die Zusammensetzung der Rhizosphärenmikroflora von Tomatenpflanzen untersucht. Es wurden jeweils ein AHL-produzierender Wildtypstamm (S. liquefaciens MG1, P. putida IsoF) und eine AHL-negative Mutante (S. liquefaciens MG44, P. putida F117), deren Fähigkeit zur AHL-Produktion unterbunden war, eingesetzt. Die Stämme waren zur in situ Lokalisierung gfp- oder rfp-markiert. Zwei Pflanzensysteme wurden dabei verwendet: Tomatenpflanzen in einem axenischen, definierten System und in einem komplexen Bodensystem. Die Wurzelbesiedlungsstudien wurden am konfokalen Laser Scanning Mikroskop (CLSM) durchgeführt und die Siedlungsdichten der Inokulate anhand der Zellzahl bestimmt. Techniken der Fluoreszenz in situ Hybridisierung (FISH) und die terminale Restriktions Fragmentlängen Polymorphismus (t-RFLP) - Analyse dienten zur Untersuchung von Veränderungen in der Zusammensetzung der Rhizosphärenpopulation. Am Beispiel von P. putida IsoF konnte die Verbreitung von AHL an der Wurzel untersucht werden. AHL wurde von den untersuchten Bakterienstämmen bei der Besiedlung der Tomatenwurzel produziert und zeigte dort eine Wirkung auf die Rhizosphärenmikroflora. Auf das Siedlungsverhalten von S. liquefaciens oder P. putida hatte die AHL-Produktionjedoch keinen Einfluß

Utilizing ITS1 and ITS2 to study environmental fungal diversity using pyrosequencing

International audienceThe shorter reads generated by high-throughput sequencing has led to a focus on either the ITS1 or the ITS2 sublocus in fungal diversity analyses. Our study aimed to determine how making this choice would influence the datasets obtained and our vision of environmental fungal diversity. DNA was extracted from different environmental samples (water, sediments and soil) and the total internal transcribed spacer (ITS) locus was amplified. 454-sequencing was performed targeting both ITS1 and ITS2. No significant differences in the number of sequences, operational taxonomic units (OTUs) and in the dominant OTUs were detected but less diversity was observed in the ITS2 dataset. In the soilsamples, differences in the fungal taxonomic identification were observed, with more Basidiomycota in the ITS1 dataset and more Ascomycota in the ITS2 dataset. Only one-third of the OTUs were detected in both datasets which could be due to (1) more short sequences removed in the ITS2 dataset, (2) different taxonomic affiliation depending on the sublocus used as BLASTn query and/or (3) selectivity in how a primer amplifies the true community. Although ITS1 and ITS2 datasets led to similar results at the fungal community level, for further in-depth diversity analysis this study suggests the analysis of both ITS regions, as they provided different information and were complementary

The Alpine mountain-plain circulation: Airborne Doppler lidar measurements and numerical simulations

On summer days radiative heating of the Alps produces rising air above the mountains and a resulting inflow of air from the foreland. This leads to a horizontal transport of air from the foreland to the Alps, and a vertical transport from the boundary layer into the free troposphere above the mountains. The structure and the transports of this mountain–plain circulation in southern Germany (“Alpine pumping”) were investigated using an airborne 2-μm scanning Doppler lidar, a wind-temperature radar, dropsondes, rawinsondes, and numerical models. The measurements were part of the Vertical Transport and Orography (VERTIKATOR) campaign in summer 2002. Comparisons of dropsonde and lidar data proved that the lidar is capable of measuring the wind direction and wind speed of this weak flow toward the Alps (1–4 m s-1). The flow was up to 1500 m deep, and it extended 80 km into the Alpine foreland. Lidar data are volume measurements (horizontal resolution 5 km, vertical resolution 100 m). Therefore, they are ideal for the investigation of the flow structure and the comparison to numerical models. Even the vertical velocities measured by the lidar agreed with the mass budget calculations in terms of both sign and magnitude. The numerical simulations with the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) (mesh size 2 and 6 km) and the Local Model (LM) of the German Weather Service (mesh size 2.8 and 7 km) reproduced the general flow structure and the mass fluxes toward the Alps within 86%–144% of the observations

Assessing what prospective laboratory assistants in biochemistry and cell biology know: development and validation of the test instrument PROKLAS

Laboratory assistants in biology and medicine play a central role in the operation of laboratories in hospitals, research institutes, and industries. Their daily work routine is characterized by dealing with molecular structures/chemical substances (i.e. biochemistry) as well as cell cultures (i.e. cell biology). In both these fields of biochemistry and cell biology, laboratory assistants rely on knowledge about three laboratory tasks: responsible action, data management, and laboratory techniques. Focusing on these laboratory tasks, we developed a test instrument measuring the professional knowledge of prospective laboratory assistants (acronym: PROKLAS) about biochemistry and cell biology.We designed a paper-and-pencil test measuring the professional knowledge of laboratory assistants required to fulfill daily laboratory tasks in biochemistry and cell biology. A sample of N = 284 Vocational Education and Training (VET) students [(average age = 20.0 years (SD = 3.3)] were tested in a cross-sectional study. The sample comprised of prospective biology laboratory assistants, biological technicians, and medical laboratory technicians.Confirmatory factor analysis (CFA) indicates that the test developed allows us to measure the professional knowledge of laboratory assistants in biochemistry and cell biology as two empirically separable constructs among laboratory assistants. CFA with covariates widely confirms the validity of PROKLAS in its respective subscales. Firstly, VET-related covariates predicted biochemistry and cell biology scores of students considerably better compared to the covariates related to general secondary school. Secondly, general biological knowledge predicted biochemistry and cell biology scores of PROKLAS. Finally, VET students’ self-efficacy in laboratory tasks and their opportunities to learn laboratory tasks are positively correlated to achievement in PROKLAS. However, we found a similar relationship for self-efficacy in English too.Our analyses indicate that PROKLAS can be effectively used for summative and formative VET evaluation in assessing the professional knowledge of laboratory assistants in biochemistry and cell biology

MOESM2 of Assessing what prospective laboratory assistants in biochemistry and cell biology know: development and validation of the test instrument PROKLAS

Additional file 2. Contains the instrument PROKLAS in German

Comparison of propofol and dexmedetomidine infused overnight to treat hyperactive and mixed ICU delirium: a protocol for the Basel ProDex clinical trial

Delirium is a neurobehavioural disturbance that frequently develops particularly in the intensive care unit (ICU) population. It was first described more than half a century ago, where it was already discovered as a state that might come along with serious complications such as prolonged ICU and hospital stay, reduced quality of life and increased mortality. However, in most cases, there is still lack of proof for causal relationship. Its presence frequently remains unrecognised due to suggested predominance of the hypoactive form. Furthermore, in the general ICU population, it has been shown that the duration of delirium is associated with worse long-term cognitive function. Due to the multifactorial origin of delirium, we have several but no incontestable treatment options. Nonetheless, delirium bears a high burden for patient, family members and the medical care team.The Basel ProDex Study targets improvement of hyperactive and mixed delirium therapy in critically ill patients. We will focus on reducing the duration and severity of delirium by implementing dexmedetomidine into the treatment plan. Dexmedetomidine compared with other sedatives shows fewer side effects representing a better risk profile for delirium treatment in general. This could further contribute to higher patient safety.The aim of the BaProDex Trial is to assess the superiority of dexmedetomidine to propofol for treatment of hyperactive and mixed delirium in the ICU. We hypothesise that dexmedetomidine, compared with propofol administered at night, shortens both the duration and severity of delirium.; The Basel ProDex Study is an investigator-initiated, one-institutional, two-centre randomised controlled clinical trial for the treatment of delirium with dexmedetomidine versus propofol in 316 critically ill patients suffering from hyperactive and mixed delirium. The primary outcome measure is delirium duration in hours. Secondary outcomes include delirium-free days at day 28, death at day 28, delirium severity, amount of ventilator days, amount of rescue sedation with haloperidol, length of ICU and hospital stay, and pharmaceutical economic analysis of the treatments. Sample size was estimated to be able to show the superiority of dexmedetomidine compared with propofol regarding the duration of delirium in hours. The trial will be externally monitored according to good clinical practice (GCP) requirements. There are no interim analyses planned for this trial.; This study will be conducted in compliance with the protocol, the current version of the Declaration of Helsinki, the International Conference on Harmonization- Good Clinical Practice (ICH-GCP) or Europäische Norm International Organization for Standardization (ISO EN 14155; as far as applicable) as well as all national legal and regulatory requirements. Only the study team will have access to trial specific data. Anonymisation will be achieved by a unique patient identification code. Trial data will be archived for a minimum of 10 years after study termination. We plan to publish the data in a major peer-reviewed clinical journal.; ClinicalTrials.gov Identifier: NCT02807467 PROTOCOL VERSION: Clinical Study Protocol Version 2, 16.08.2016

Induction of systemic resistance in tomato by N-acyl-L-homoserine lactone-producing rhizosphere bacteria.

N-acyl-L-homoserine lactone (AHL) signal molecules are utilized by Gram-negative bacteria to monitor their population density (quorum sensing) and to regulate gene expression in a density-dependent manner. We show that Serratia liquefaciens MG1 and Pseudomonas putida IsoF colonize tomato roots, produce AHL in the rhizosphere and increase systemic resistance of tomato plants against the fungal leaf pathogen, Alternaria alternata. The AHL-negative mutant S. liquefaciens MG44 was less effective in reducing symptoms and A. alternata growth as compared to the wild type. Salicylic acid (SA) levels were increased in leaves when AHL-producing bacteria colonized the rhizosphere. No effects were observed when isogenic AHL-negative mutant derivatives were used in these experiments. Furthermore, macroarray and Northern blot analysis revealed that AHL molecules systemically induce SA- and ethylene-dependent defence genes (i.e. PR1a, 26 kDa acidic and 30 kDa basic chitinase). Together, these data support the view that AHL molecules play a role in the biocontrol activity of rhizobacteria through the induction of systemic resistance to pathogens

Induction of systemic resistance in tomato by N-acyl-L-homoserine lactone-producing rhizosphere bacteria

N-acyl-L-homoserine lactone (AHL) signal molecules are utilized by Gram-negative bacteria to monitor their population density (quorum sensing) and to regulate gene expression in a density-dependent manner. We show that Serratia liquefaciens MG1 and Pseudomonas putida IsoF colonize tomato roots, produce AHL in the rhizosphere and increase systemic resistance of tomato plants against the fungal leaf pathogen, Alternaria alternata. The AHL-negative mutant S. liquefaciens MG44 was less effective in reducing symptoms and A. alternata growth as compared to the wild type. Salicylic acid (SA) levels were increased in leaves when AHL-producing bacteria colonized the rhizosphere. No effects were observed when isogenic AHL-negative mutant derivatives were used in these experiments. Furthermore, macroarray and Northern blot analysis revealed that AHL molecules systemically induce SA- and ethylene-dependent defence genes (i.e. PR1a, 26 kDa acidic and 30 kDa basic chitinase). Together, these data support the view that AHL molecules play a role in the biocontrol activity of rhizobacteria through the induction of systemic resistance to pathogens