15 research outputs found

    Cortical evidence for negative search templates

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    A “target template”, specifying target features, is thought to benefit visual search performance. Setting up a “negative template”, specifying distractor features, should improve distractor inhibition and also benefit target detection. In the current fMRI study, subjects were required to search for a target among distractors enclosed in coloured circles. Before search, one of three colour cues appeared: a positive cue indicating the target will appear in the same colour, a negative cue indicating only distractors will appear in the same colour, or a neutral cue indicating that the same colour will not appear in the search display. fMRI results revealed down-regulation of neural processing in large parts of visual cortex following negative compared to positive cues. We further found a general attention inhibition mechanism in SPL/precuneus for neutral cues compared to positive and negative cues. These results suggest a cortical distinction between target templates, negative templates, and task-irrelevant distractor inhibition

    Dandruff-associated Malassezia genomes reveal convergent and divergent virulence traits shared with plant and human fungal pathogens

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    Fungi in the genus Malassezia are ubiquitous skin residents of humans and other warm-blooded animals. Malassezia are involved in disorders including dandruff and seborrheic dermatitis, which together affect >50% of humans. Despite the importance of Malassezia in common skin diseases, remarkably little is known at the molecular level. We describe the genome, secretory proteome, and expression of selected genes of Malassezia globosa. Further, we report a comparative survey of the genome and secretory proteome of Malassezia restricta, a close relative implicated in similar skin disorders. Adaptation to the skin environment and associated pathogenicity may be due to unique metabolic limitations and capabilities. For example, the lipid dependence of M. globosa can be explained by the apparent absence of a fatty acid synthase gene. The inability to synthesize fatty acids may be complemented by the presence of multiple secreted lipases to aid in harvesting host lipids. In addition, an abundance of genes encoding secreted hydrolases (e.g., lipases, phospholipases, aspartyl proteases, and acid sphingomyelinases) was found in the M. globosa genome. In contrast, the phylogenetically closely related plant pathogen Ustilago maydis encodes a different arsenal of extracellular hydrolases with more copies of glycosyl hydrolase genes. M. globosa shares a similar arsenal of extracellular hydrolases with the phylogenetically distant human pathogen, Candida albicans, which occupies a similar niche, indicating the importance of host-specific adaptation. The M. globosa genome sequence also revealed the presence of mating-type genes, providing an indication that Malassezia may be capable of sex.
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