Genomic islands: tools of bacterial horizontal gene transfer and evolution

Bacterial genomes evolve through mutations, rearrangements or horizontal gene transfer. Besides the core genes encoding essential metabolic functions, bacterial genomes also harbour a number of accessory genes acquired by horizontal gene transfer that might be beneficial under certain environmental conditions. The horizontal gene transfer contributes to the diversification and adaptation of microorganisms, thus having an impact on the genome plasticity. A significant part of the horizontal gene transfer is or has been facilitated by genomic islands (GEIs). GEIs are discrete DNA segments, some of which are mobile and others which are not, or are no longer mobile, which differ among closely related strains. A number of GEIs are capable of integration into the chromosome of the host, excision, and transfer to a new host by transformation, conjugation or transduction. GEIs play a crucial role in the evolution of a broad spectrum of bacteria as they are involved in the dissemination of variable genes, including antibiotic resistance and virulence genes leading to generation of hospital ‘superbugs’, as well as catabolic genes leading to formation of new metabolic pathways. Depending on the composition of gene modules, the same type of GEIs can promote survival of pathogenic as well as environmental bacteria

Characterization of the Single Stranded DNA Binding Protein SsbB Encoded in the Gonoccocal Genetic Island

Background: Most strains of Neisseria gonorrhoeae carry a Gonococcal Genetic Island which encodes a type IV secretion system involved in the secretion of ssDNA. We characterize the GGI-encoded ssDNA binding protein, SsbB. Close homologs of SsbB are located within a conserved genetic cluster found in genetic islands of different proteobacteria. This cluster encodes DNA-processing enzymes such as the ParA and ParB partitioning proteins, the TopB topoisomerase, and four conserved hypothetical proteins. The SsbB homologs found in these clusters form a family separated from other ssDNA binding proteins. Methodology/Principal Findings: In contrast to most other SSBs, SsbB did not complement the Escherichia coli ssb deletion mutant. Purified SsbB forms a stable tetramer. Electrophoretic mobility shift assays and fluorescence titration assays, as well as atomic force microscopy demonstrate that SsbB binds ssDNA specifically with high affinity. SsbB binds single-stranded DNA with minimal binding frames for one or two SsbB tetramers of 15 and 70 nucleotides. The binding mode was independent of increasing Mg 2+ or NaCl concentrations. No role of SsbB in ssDNA secretion or DNA uptake could be identified, but SsbB strongly stimulated Topoisomerase I activity

Structure-Based Design of Non-Natural Amino Acid Inhibitors of Amyloid Fibrillation

Many globular and natively disordered proteins can convert into amyloid fibers. These fibers are associated with numerous pathologies1 as well as with normal cellular functions2,3, and frequently form during protein denaturation4,5. Inhibitors of pathological amyloid fibers could serve as leads for therapeutics, provided the inhibitors were specific enough to avoid interfering with normal processes. Here we show that computer-aided, structure-based design can yield highly specific peptide inhibitors of amyloid formation. Using known atomic structures of segments of amyloid fibers as templates, we have designed and characterized an all D-amino acid inhibitor of fibrillation of the tau protein found in Alzheimer’s disease, and a non-natural L-amino acid inhibitor of an amyloid fiber that enhances sexual transmission of HIV. Our results indicate that peptides from structure-based designs can disrupt the fibrillation of full-length proteins, including those like tau that lack fully ordered native structures.We thank M.I. Ivanova, J. Corn, T. Kortemme, D. Anderson, M.R. Sawaya, M. Phillips, S. Sambashivan, J. Park, M. Landau, Q. Zhang, R. Clubb, F. Guo, T. Yeates, J. Nowick, J. Zheng, and M.J. Thompson for discussions, HHMI, NIH, NSF, the GATES foundation, and the Joint Center for Translational Medicine for support, R. Peterson for help with NMR experiments, E. Mandelkow for providing tau constructs, R. Riek for providing amyloid beta, J. Stroud for amyloid beta preparation. Support for JK was from the Damon Runyon Cancer Research Foundation, for HWC by the Ruth L. Kirschstein National Research Service Award, for JM from the programme for junior-professors by the ministry of science, Baden-Württemberg, and for SAS by a UCLA-IGERT bioinformatics traineeship

Absorbing customer knowledge: how customer involvement enables service design success

Customers are a knowledge resource outside of the firm that can be utilized for new service success by involving them in the design process. However, existing research on the impact of customer involvement (CI) is inconclusive. Knowledge about customers’ needs and on how best to serve these needs (articulated in the service concept) is best obtained from customers themselves. However, codesign runs the risk of losing control of the service concept. This research argues that of the processes of external knowledge, acquisition (via CI), customer knowledge assimilation, and concept transformation form a capability that enables the firm to exploit customer knowledge in the form of a successful new service. Data from a survey of 126 new service projects show that the impact of CI on new service success is fully mediated by customer knowledge assimilation (the deep understanding of customers’ latent needs) and concept transformation (the modification of the service concept due to customer insights). However, its impact is more nuanced. CI exhibits an “∩”-shaped relationship with transformation, indicating there is a limit to the beneficial effect of CI. Its relationship with assimilation is “U” shaped, suggesting a problem with cognitive inertia where initial learnings are ignored. Customer knowledge assimilation directly impacts success, while concept transformation only helps success in the presence of resource slack. An evolving new service design is only beneficial if the firm has the flexibility to adapt to change

Population Structure of Pseudomonas aeruginosa from Five Mediterranean Countries: Evidence for Frequent Recombination and Epidemic Occurrence of CC235

Several studies in recent years have provided evidence that Pseudomonas aeruginosa has a non-clonal population structure punctuated by highly successful epidemic clones or clonal complexes. The role of recombination in the diversification of P. aeruginosa clones has been suggested, but not yet demonstrated using multi-locus sequence typing (MLST). Isolates of P. aeruginosa from five Mediterranean countries (n = 141) were subjected to pulsed-field gel electrophoresis (PFGE), serotyping and PCR targeting the virulence genes exoS and exoU. The occurrence of multi-resistance (≥3 antipseudomonal drugs) was analyzed with disk diffusion according to EUCAST. MLST was performed on a subset of strains (n = 110) most of them had a distinct PFGE variant. MLST data were analyzed with Bionumerics 6.0, using minimal spanning tree (MST) as well as eBURST. Measurement of clonality was assessed by the standardized index of association (IAS). Evidence of recombination was estimated by ClonalFrame as well as SplitsTree4.0. The MST analysis connected 70 sequence types, among which ST235 was by far the most common. ST235 was very frequently associated with the O11 serotype, and frequently displayed multi-resistance and the virulence genotype exoS−/exoU+. ClonalFrame linked several groups previously identified by eBURST and MST, and provided insight to the evolutionary events occurring in the population; the recombination/mutation ratio was found to be 8.4. A Neighbor-Net analysis based on the concatenated sequences revealed a complex network, providing evidence of frequent recombination. The index of association when all the strains were considered indicated a freely recombining population. P. aeruginosa isolates from the Mediterranean countries display an epidemic population structure, particularly dominated by ST235-O11, which has earlier also been coupled to the spread of ß-lactamases in many countries

eine prospektive Kohortenstudie

Objective: The Mental Adjustment to Cancer Scale (MAC scale) has evolved to a standard measure in the field of psycho-oncology. In this context an attitude called "fighting spirit" gained much attention as a coping style. Some reports suggest that coping efforts as measured by the MAC scale are predictive for survival of breast cancer patients. We explored the predictive power of the MAC scale by using a sample of patients with haematological malignancies undergoing allogenic hemopoietic stem cell transplantation (HSCT). Methods: Between 9/1999 and 12/2001 127 patients were administered the MAC scale prior to HSCT. Follow-up data of overall survival and event-free survival were obtained in December 2003 and analyzed using Cox-regression models. Results: At the time of the follow-up, 68 patients had died (overall survival), 75 patients had experienced a relapse or had died (event-free survival). We failed to find significant results for the MAC subscales with and without adjustment for prognostic factors. Conclusion: In the special situation of patients facing HSCT the MAC scale seems not to be of predictive value. In general, with respect to survival the empirical evidence is not very convincing.Zielsetzung: Die Mental Adjustment to Cancer Scale (MAC-Skala) hat sich im Feld der Psychoonkologie zu einem Standardmessinstrument entwickelt. In diesem Zusammenhang gewann ein als "fighting spirit" bezeichneter Bewältigungsstil breite Aufmerksamkeit. In manchen Studien wurde berichtet, dass mit der MAC-Skala erfasste Krankheitsverarbeitungsweisen mit späterer Überlebensdauer korreliert sind. Wir untersuchten die Vorhersagekraft der MAC-Skala in einer Stichprobe von Patienten mit hämatologischen Erkrankungen, die sich einer allogenen hämatopoietischen Stammzelltransplantation (HSZT) unterzogen. Methode: Zwischen 9/1999 und 12/2001 bearbeiteten 127 Patienten die MAC-Skala vor Durchführung der HSZT. Ein Follow-up im Hinblick auf Überlebenszeit erfolgte im Dezember 2003. Die Überlebenszeitdaten wurden mit Cox-Regressionsmodellen evaluiert. Ergebnisse: 68 Patienten waren verstorben, 75 Patienten waren verstorben oder erlitten Rezidiv. Es wurden mit und ohne Adjustierung bezüglich medizinischer Prognosefaktoren keine signifikanten Zusammenhänge einer der MAC-Subskalen mit der allgemeinen und der krankheitsfreien Überlebenszeit gefunden. Fazit: In der speziellen Situation vor HSZT scheint die MAC-Skala keinen Vorhersagewert für die Überlebenszeit zu haben. Jedoch gilt auch allgemein, dass die empirische Evidenz in dieser Hinsicht nicht überzeugend ist

Baroreceptor stimulation: Pain perception and sensory thresholds

Baroreceptor activity has been implicated in the modulation of pain. Sensory detection thresholds and pain ratings were measured in a group of 28 men during carotid baroreceptor manipulation with the PRES (phase-related external suction) neck suction technique. Brief, cardiac phase-related electrical impulses were delivered intracutaneously to the finger. The results indicate that minimum baroreceptor activity was associated with more severe pain, but had no effect on sensory detection threshold. The results are discussed in terms of the learned model of hypertension

Somatosensory stimulation during social support activities anterior cingulate and insular cortices in chronic pain patients

Our previous research has revealed that pain perception in chronic pain patients may be influenced by the presence of their significant others. Recently, it has been further shown that affective components of the neural pain network are more activated than sensory components during the experience of another’s pain in healthy controls. In the present study, we investigated whether the presence vs. absence of a patient’s significant othermay also differentially influence brain activity of the pain network in chronic pain patients. Ten female patients with fibromyalgia (aged 51.2 yrs) and nine female healthy controls (aged 55.3 yrs)were examined using fMRI when somatosensory stimulation was elicited by non-painful vibratory stimuli at the elbow and at the finger. Significantly greater activations were found in the insula, anterior cingulate cortex (ACC), and secondary somatosensory cortex (SII) in fibromyalgia patients compared to healthy controls when stimuli were applied at the elbow (one of the tender points considered by patients with fibromyalgia) in the presence of the patient’s partner; but no group differences in brain activity were observed when stimuli were applied in the absence of the patient’s partner, or when stimuli were applied at the finger.We concluded that social support froma patient’s significant other in chronic pain patients may activate both sensory and affective components of the brain network involved in pain processing