Arginine residues in domain V have a central role for bacteria-binding activity of macrophage scavenger receptor MARCO

MARCO is a bacteria-binding macrophage-specific scavenger receptor that plays a role in innate immune response. MARCO has short intracellular and transmembrane domains, as well as a large extracellular domain composed of a spacer domain, a long collagenous domain, and a C-terminal scavenger receptor cysteine-rich domain (SRCR), domain V. As yet, no specific function has been assigned to the SRCR domain of scavenger receptors. In the present study, we generated several human and mouse MARCO variants with deletions or single amino acid substitutions and localized the primary bacteria-binding region to domain V. Furthermore, analysis of the MARCO variants containing only portions of domain V demonstrated a crucial role for an arginine-rich segment for this function. More precisely, the motif RXR was identified as an essential element for high-affinity bacterial binding. The results indicate that the binding properties of MARCO differ from those of the other class A scavenger receptors, SR-A and SRCL, whose ligand-binding function has been localized to the collagenous domain.     

Infection of Acanthamoeba castellanii with Mycobacterium bovis and M. bovis BCG and survival of M. bovis within the amoebae

Survival of Mycobacterium bovis after ingestion by protozoa would provide an environmental reservoir for infection of cattle. We have shown that M. bovis survived ingestion by Acanthamoeba castellanii. In contrast, two strains of M. bovis BCG did not survive well within Acanthamoeba.     

Inhibition of nicotinoprotein (NAD+-containing) alcohol dehydrogenase by trans-4-(N,N-dimethylamino)-cinnamaldehyde binding to the active site

Ethanol oxidation by nicotinoprotein alcohol dehydrogenase (np-ADH) from the bacterium Amycolatopsis methanolica is inhibited by trans-4-(N,N-dimethylamino)-cinnamaldehyde through direct binding to the catalytic zinc ion in a substrate-like geometry. This binding is accompanied by a characteristic red shift of the aldehyde absorbance from 398 nm to 467 nm. Np-ADH is structurally related to mammalian ADH class I, and a model of np-ADH shows how the cinnamaldehyde derivative can be accommodated in the active site of the nicotinoprotein, correlating the structural and enzymological data.     

Molecular characterization of UV-treated sugar beet somaclones using RFLP markers

Sugar beet plants regenerated from UV-treated calluses were examined by restriction fragment length polymorphism (RFLP) analysis to determine the extent of somaclonal variation occurring at the DNA level. In total, 50 random sugar beet DNA sequences were used to screen 42 somaclones for genetic alterations. Three polymorphisms were detected among the 7 644 alleles analysed. From these data a mutation frequency of 0.03 ± 0.02% per allele was estimated. This frequency is in agreement with similar studies of somaclonal DNA variation using molecular markers and lies in the upper range of the spontaneous gene mutation frequencies found in plants. The two probegenotype combinations showing independent polymorphisms, were further analysed using the restriction enzymes Bam HI, Eco RI, Eco RV and Hind III. Both polymorphisms are likely to result from structural rearrangements rather than from point mutations. Differences in methylation among 10 of the investigated somaclones were tested for by comparing Hpa II and Msp I generated RFLP patterns. The somaclones showed extensive methylation, but no differences in their degree of methylation. Cytological analysis revealed 34 diploid, 8 tetraploid, but no aneuploid plants.     

Hook Proteins: Association with Alzheimer Pathology and Regulatory Role of Hook3 in Amyloid Beta Generation

Defects in intracellular transport are implicated in the pathogenesis of Alzheimer’s disease (AD). Hook proteins are a family of cytoplasmic linker proteins that participate in endosomal transport. In this study we show that Hook1 and Hook3 are expressed in neurons while Hook2 is predominantly expressed in astrocytes. Furthermore, Hook proteins are associated with pathological hallmarks in AD; Hook1 and Hook3 are localized to tau aggregates and Hook2 to glial components within amyloid plaques. Additionally, the expression of Hook3 is reduced in AD. Modelling of Hook3 deficiency in cultured cells leads to slowing of endosomal transport and increases β-amyloid production. We propose that Hook3 plays a role in pathogenic events exacerbating AD.     

Decline in Coronary Mortality in Sweden between 1986 and 2002: Comparing Contributions from Primary and Secondary Prevention

BackgroundThe relative importance of risk factor reduction in healthy people (primary prevention) versus that in patients with coronary heart disease (secondary prevention) has been debated. We aimed to quantify the contribution of the two.MethodologyWe used the previously validated IMPACT model to estimate contributions from primary prevention (reducing risk factors in the population, particularly smoking, cholesterol and systolic blood pressure) and from secondary prevention (reducing risk factors in coronary heart disease patients) in the Swedish population.ConclusionsThe largest effects on mortality came from primary prevention, giving markedly larger mortality reductions than secondary prevention.     

Genus-Wide Comparative Genomics of Malassezia Delineates Its Phylogeny,Physiology, and Niche Adaptation on Human Skin

Malassezia is a unique lipophilic genus in class Malasseziomycetes in Ustilaginomycotina, (Basidiomycota, fungi) that otherwise consists almost exclusively of plant pathogens. Malassezia are typically isolated from warm-blooded animals, are dominant members of the human skin mycobiome and are associated with common skin disorders. To characterize the genetic basis of the unique phenotypes of Malassezia spp., we sequenced the genomes of all 14 accepted species and used comparative genomics against a broad panel of fungal genomes to comprehensively identify distinct features that define the Malassezia gene repertoire: gene gain and loss; selection signatures; and lineage-specific gene family expansions. Our analysis revealed key gene gain events (64) with a single gene conserved across all Malassezia but absent in all other sequenced Basidiomycota. These likely horizontally transferred genes provide intriguing gain-of-function events and prime candidates to explain the emergence of Malassezia. A larger set of genes (741) were lost, with enrichment for glycosyl hydrolases and carbohydrate metabolism, concordant with adaptation to skin’s carbohydrate-deficient environment. Gene family analysis revealed extensive turnover and underlined the importance of secretory lipases, phospholipases, aspartyl proteases, and other peptidases. Combining genomic analysis with a re-evaluation of culture characteristics, we establish the likely lipid-dependence of all Malassezia. Our phylogenetic analysis sheds new light on the relationship between Malassezia and other members of Ustilaginomycotina, as well as phylogenetic lineages within the genus. Overall, our study provides a unique genomic resource for understanding Malassezia niche-specificity and potential virulence, as well as their abundance and distribution in the environment and on human skin.