226 research outputs found

    Expression of the \u3cem\u3eDistalless-B\u3c/em\u3e gene in \u3cem\u3eCiona\u3c/em\u3e is regulated by a pan-ectodermal enhancer module

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    The Ci-Dll-B gene is an early regulator of ectodermal development in the ascidian Ciona intestinalis (Imai et al., 2006). Ci-Dll-B is located in a convergently transcribed bigene cluster with a tandem duplicate, Ci-Dll-A. This clustered genomic arrangement is the same as those of the homologous vertebrate Dlx genes, which are also arranged in convergently transcribed bigene clusters. Sequence analysis of the C. intestinalis Dll-A-B cluster reveals a 378 bp region upstream of Ci-Dll-B, termed B1, which is highly conserved with the corresponding region from the congener Ciona savignyi. The B1 element is necessary and sufficient to drive expression of a lacZ reporter gene in a pattern mimicking the endogenous expression of Ci-Dll-B at gastrula stages. This expression pattern which is specific to the entire animal hemisphere is activated preferentially in posterior, or b-lineage, cells by a central portion of B1. Expression in anterior, or a-lineage cells, can be activated by this central portion in combination with the distal part of B1. Anterior expression can also be activated by the central part of B1 plus both the proximal part of B1 and non-conserved sequence upstream of B1. Thus, cis-regulation of early Ci-Dll-B expression is activated by a required submodule in the center of B1, driving posterior expression, which works in combination with redundant submodules that respond to differentially localized anterior factors to produce the total animal hemisphere expression pattern. Interestingly, the intergenic region of the cluster, which is important for expression of the Dlx genes in vertebrates, does not have a specific activating function in the reporter genes tested, but acts as an attenuator in combination with upstream sequences

    Evolutionary, ecological and biotechnological perspectives on plasmids resident in the human gut mobile metagenome

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    Numerous mobile genetic elements (MGE) are associated with the human gut microbiota and collectively referred to as the gut mobile metagenome. The role of this flexible gene pool in development and functioning of the gut microbial community remains largely unexplored, yet recent evidence suggests that at least some MGE comprising this fraction of the gut microbiome reflect the co-evolution of host and microbe in the gastro-intestinal tract. In conjunction, the high level of novel gene content typical of MGE coupled with their predicted high diversity, suggests that the mobile metagenome constitutes an immense and largely unexplored gene-space likely to encode many novel activities with potential biotechnological or pharmaceutical value, as well as being important to the development and functioning of the gut microbiota. Of the various types of MGE that comprise the gut mobile metagenome, plasmids are of particular importance since these elements are often capable of autonomous transfer between disparate bacterial species, and are known to encode accessory functions that increase bacterial fitness in a given environment facilitating bacterial adaptation. In this article current knowledge regarding plasmids resident in the human gut mobile metagenome is reviewed, and available strategies to access and characterize this portion of the gut microbiome are described. The relative merits of these methods and their present as well as prospective impact on our understanding of the human gut microbiota is discussed

    Salmonella-Induced Mucosal Lectin RegIIIβ Kills Competing Gut Microbiota

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    Intestinal inflammation induces alterations of the gut microbiota and promotes overgrowth of the enteric pathogen Salmonella enterica by largely unknown mechanisms. Here, we identified a host factor involved in this process. Specifically, the C-type lectin RegIIIβ is strongly upregulated during mucosal infection and released into the gut lumen. In vitro, RegIIIβ kills diverse commensal gut bacteria but not Salmonella enterica subspecies I serovar Typhimurium (S. Typhimurium). Protection of the pathogen was attributable to its specific cell envelope structure. Co-infection experiments with an avirulent S. Typhimurium mutant and a RegIIIβ-sensitive commensal E. coli strain demonstrated that feeding of RegIIIβ was sufficient for suppressing commensals in the absence of all other changes inflicted by mucosal disease. These data suggest that RegIIIβ production by the host can promote S. Typhimurium infection by eliminating inhibitory gut microbiota

    Introduction—Food Security and Food Waste Reduction: A Social Innovation Approach to Current Social, Environmental, and Political Concerns

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    This chapter presents the research rationale underpinning the book. It addresses the intertwining challenges of food security and surplus food management, discussing recent data and literature. It also presents how social innovation is conceptualized in the book as the theoretical framework to analyse partnerships between business and non-profit organisations in managing food surplus. The methodology of the research is also detailed, along with the book structure

    A longitudinal analysis of motivation profiles at work

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    This paper examines the multidimensional nature of workplace motivation and the importance of a continuum structure in self-determination theory through application of complementary variable- and person-centered approaches. This approach is taken to simultaneously model the complexity of motivation and highlight interactions between motivational factors. Additionally, this study represents an initial test of the temporal stability of work motivation profiles. A sample of 510 full-time employees were recruited from a range of occupations. Results support the central importance of a general factor representing self-determination as the most influential factor in an employee’s motivation profile. However, smaller effects associated with the motivation subscales, especially identified regulation, were also noticed. Importantly, motivation profiles were found to be highly stable over the 4-month duration of this study. Results lend support to the theoretical position that while general self-determination is an essential component of motivation, it alone does not fully describe an employee’s motivation
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