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

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.

The Big Society and the conjunction of crises: Justifying welfare reform and undermining social housing

This article considers the idea of the ‘Big Society’ as part of a long-standing debate about the regulation of housing. Situating the concept within governance theory, the article considers how the idea of the Big Society was used by the UK coalition government to justify a radical restructuring of welfare provision. The fundamental rationale for this transformation was that the UK was forced to respond to a conjunction of crises in morality, the state, ideology and economics. Representing a fundamental departure from earlier attempts at welfare reform, the government has undertaken a reform programme which has had a severe effect on the social housing sector. The article argues that the result has been a combination of libertarianism and authoritarianism, alongside an intentionally more destructive combination of stigmatization and fatalism. The consequence is to undermine the principle of social housing which will not only prove detrimental for residents but raises significant dilemmas for those working in the housing sector.