The stealth episome: suppression of gene expression on the excised genomic island PPHGI-1 from Pseudomonas syringae pv. phaseolicola

Pseudomonas syringae pv. phaseolicola is the causative agent of halo blight in the common bean, Phaseolus vulgaris. P. syringae pv. phaseolicola race 4 strain 1302A contains the avirulence gene avrPphB (syn. hopAR1), which resides on PPHGI-1, a 106 kb genomic island. Loss of PPHGI-1 from P. syringae pv. phaseolicola 1302A following exposure to the hypersensitive resistance response (HR) leads to the evolution of strains with altered virulence. Here we have used fluorescent protein reporter systems to gain insight into the mobility of PPHGI-1. Confocal imaging of dual-labelled P. syringae pv. phaseolicola 1302A strain, F532 (dsRFP in chromosome and eGFP in PPHGI-1), revealed loss of PPHGI-1::eGFP encoded fluorescence during plant infection and when grown in vitro on extracted leaf apoplastic fluids. Fluorescence-activated cell sorting (FACS) of fluorescent and non-fluorescent PPHGI-1::eGFP F532 populations showed that cells lost fluorescence not only when the GI was deleted, but also when it had excised and was present as a circular episome. In addition to reduced expression of eGFP, quantitative PCR on sub-populations separated by FACS showed that transcription of other genes on PPHGI-1 (avrPphB and xerC) was also greatly reduced in F532 cells harbouring the excised PPHGI-1::eGFP episome. Our results show how virulence determinants located on mobile pathogenicity islands may be hidden from detection by host surveillance systems through the suppression of gene expression in the episomal state

Closer look at the flight dynamics of wings with non-elliptic lift distributions

Prandtl’s alternative solution for wings with minimum induced drag opens another route for improving aircraft performance especially at the conceptual design phase. In this work, the lateral-directional characteristics of such wings are studied for a glider use case from a per-spective that focuses on pro verse yaw and handling qualities. The authors propose an aileron design methodology that ensures roll authority and proverse yaw characteristics. The resultsshow that these conditions cannot be satisfied by a conventional Elliptic configuration, whereaswings with non-elliptic distributions provide several solutions. Non-linear flight dynamic mod-els of the configurations that provided maximum proverse yaw were assessed in an engineering simulator and compared against the baseline Elliptic case. Proverse yaw was observed in thesimulation data and pilot feedback indicated improved handling qualities in the non-elliptic cases. However, the inherent directional instability combined with other lateral-directional coupling effects masked the observations from the pilot’s perspective

Die sittlich-religiösen Ideale der Bektaschi-Mönche: nach Mehmet Hilmi

Donated by Klaus KreiserReprinted from in : Der neue Orient, 191

Die sittlich-religiösen Ideale der Bektaschi-Mönche: nach Mehmet Hilmi

Donated by Klaus Kreise