University of Westminster

About: University of Westminster is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Politics. The organization has 2944 authors who have published 8426 publications receiving 200236 citations. The organization is also known as: Westminster University & Royal Polytechnic Institution.

Identification of bacteria associated with Dinoflagellates (Dinophyceae) Alexandrium spp. using tyramide signal amplification fluorescent in situ hybridization and confocal microscopy

Abstract: In the marine environment, phytoplankton and bacterioplankton can be physically associated. Such association has recently been hypothesized to be involved in the toxicity of the dinoflagellate genus Alexandrium. However, the methods, which have been used so far to identify, localize, and quantify bacteria associated with phytoplankton, are either destructive, time consuming, or lack precision. In the present study we combined tyramide signal amplification–fluorescent in situ hybridization (TSA-FISH) with confocal microscopy to determine the physical association of dinoflagellate cells with bacteria. Dinoflagellate attached microflora was successfully identified with TSA-FISH, whereas FISH using monolabeled probes failed to detect bacteria, because of the dinoflagellate autofluorescence. Bacteria attached to entire dinoflagellates were further localized and distinguished from those attached to empty theca, by using calcofluor and DAPI, two fluorochromes that stain dinoflagellate theca and DNA, respectively. The contribution of specific bacterial taxa of attached microflora was assessed by double hybridization. Endocytoplasmic and endonuclear bacteria were successfully identified in the nonthecate dinoflagellate Gyrodinium instriatum. In contrast, intracellular bacteria were not observed in either toxic or nontoxic strains of Alexandrium spp. Finally, the method was successfully tested on natural phytoplankton assemblages, suggesting that this combination of techniques could prove a useful tool for the simultaneous identification, localization, and quantification of bacteria physically associated with dinoflagellates and more generally with phytoplankton.

Balanced mechanical forces and microtubule contribution to fibroblast contraction

Abstract: Fibroblast locomotion is thought to generate tractional forces which lead to contraction and reorganisation of collagen in tissue development and repair. A culture force monitor device (CFM) was used to measure changes in force in fibroblast populated collagen lattices, which resulted from cytoskeletal reorganisation by cytochalasin B, colchicine, vinblastine, and taxol. Microfilament disruption abolished contraction forces, microtubule disruption elicited a new peak of contraction, while taxol stabilisation of microtubules produced a gradual fall in measured force across the collagen gel. Based on these measurements, it is suggested that the cell can be viewed as an engineering structure in which residual intracellular forces, from contractile microfilaments, exert compressive loading on microtubular elements. This microtubular structure appears to act as a ''balanced space frame'' (analogous to an aeroplane chassis), maintaining cell shape and consequently storing a residual internal tension (RIT). In dermal fibroblasts this hidden RIT was up to 33% of the measurable force exerted on the collagen gel. Phenotypic differences between space frame organisation and RIT levels could explain site and pathological variations in fibroblast contraction. (C) 1996 Wiley-Liss, Inc.

Insight, grey matter and cognitive function in first-onset psychosis.

Abstract: BACKGROUND: Several studies have suggested that neuropsychological and structural brain deficits are implicated in poor insight. Few insight studies however have combined neurocognitive and structural neuroanatomical measures. AIMS: Focusing on the ability to relabel psychotic symptoms as pathological, we examined insight, brain structure and neurocognition in first-onset psychosis. METHOD: Voxel-based magnetic resonance imaging data were acquired from 82 individuals with psychosis and 91 controls assessed with a brief neuropsychological test battery. Insight was measured using the Schedule for the Assessment of Insight. RESULTS: The principal analysis showed reduced general neuropsychological function was linked to poor symptom relabelling ability. A subsequent between-psychosis group analysis found those with no symptom relabelling ability had significant global and regional grey matter deficits primarily located at the posterior cingulate gyrus and right precuneus/cuneus. CONCLUSIONS: The cingulate gyrus (as part of a midline cortical system) along with right hemisphere regions may be involved in illness and symptom self-appraisal in first-onset psychosis.