Premature refutation of a human-mediated marine species introduction: the case history of the marine snail <Emphasis Type="Italic">Littorina littorea</Emphasis> in the Northwestern Atlantic

The closely documented spread of the European periwinkle snail, Littorina littorea from Pictou, Nova Scotia in 1840 to New Jersey by 1870, its near absence in pre-European fossil deposits, and its close association with human mechanisms of transport from Europe, are among the clearest evidence of a human-mediated marine introduction ever reported. Genetic data were recently proposed as evidence that North American L. littorea predate European contact and thus, are not introduced. Review of these genetic data and all other data reveals that the simplest explanation of the modern occurrence of this snail in North America is by human introduction.     

RNA interference in parasitic nematodes of animals: a reality check?

RNA interference (RNAi) is widely used in Caenorhabditis elegans to identify gene function and has been adapted as a high-throughput screening method to identify genes involved in essential processes. The technique has been applied to parasitic nematodes with variable success and we believe that inconsistent outcomes preclude its use as a robust screen with which to identify potential control targets. In this article, key issues that require clarification are discussed, including the mode of delivery of double-stranded RNA to the parasite, the developmental stage targeted and, perhaps of most importance, whether the RNAi pathway (as defined by studies in C. elegans) is fully functional in some parasitic nematodes.     

Dietary contributions of the alien zebra mussel Dreissena polymorpha in British freshwater fish suggest low biological resistance to their invasion

Hydrobiologia - Native communities can resist the establishment and invasion of alien species through consumptive and/or competitive interactions. The extent of consumptive resistance from...     

Nucleosome compaction facilitates HP1γ binding to methylated H3K9

The α, β and γ isoforms of mammalian heterochromatin protein 1 (HP1) selectively bind to methylated lysine 9 of histone H3 via their chromodomains. Although the phenotypes of HP1-knockout mice are distinct for each isoform, the molecular mechanisms underlying HP1 isoform-specific function remain elusive. In the present study, we found that in contrast to HP1α, HP1γ could not bind tri-methylated H3 lysine 9 in a reconstituted tetra-nucleosomes when the nucleosomes were in an uncompacted state. The hinge region connecting HP1''s chromodomain and chromoshadow domain contributed to the distinct recognition of the nucleosomes by HP1α and HP1γ. HP1γ, but not HP1α, was strongly enhanced in selective binding to tri-methylated lysine 9 in histone H3 by the addition of Mg²⁺ or linker histone H1, which are known to induce compaction of nucleosomes. We propose that this novel property of HP1γ recognition of lysine 9 in the histone H3 tail in different nucleosome structures plays a role in reading the histone code.     

Coronavirus nsp6 proteins generate autophagosomes from the endoplasmic reticulum via an omegasome intermediate

Autophagy is a cellular response to starvation which generates autophagosomes to carry cellular organelles and long-lived proteins to lysosomes for degradation. Degradation through autophagy can provide an innate defence against virus infection, or conversely autophagosomes can promote infection by facilitating assembly of replicase proteins. We demonstrate that the avian coronavirus, Infectious Bronchitis Virus (IBV) activates autophagy. A screen of individual IBV non-structural proteins (nsps) showed that autophagy was activated by IBV nsp6. This property was shared with nsp6 of mammalian coronaviruses Mouse Hepatitis Virus, and Severe Acute Respiratory Syndrome Virus, and the equivalent nsp5-7 of the arterivirus Porcine Reproductive and Respiratory Syndrome Virus. These multiple-spanning transmembrane proteins located to the endoplasmic reticulum (ER) where they generated Atg5 and LC3II-positive vesicles, and vesicle formation was dependent on Atg5 and class III PI3 kinase. The vesicles recruited double FYVE-domain containing protein (DFCP) indicating localised concentration of phosphatidylinositol 3 phosphate, and therefore shared many features with omegasomes formed from the ER in response to starvation. Omegasomes induced by viral nsp6 matured into autophagosomes that delivered LC3 to lysosomes and therefore recruited and recycled the proteins needed for autophagosome nucleation, expansion, cellular trafficking and delivery of cargo to lysosomes. The coronavirus nsp6 proteins activated omegasome and autophagosome formation independently of starvation, but activation did not involve direct inhibition of mTOR signalling, activation of sirtuin1 or induction of ER stress.     

Identification, replication, and fine-mapping of Loci associated with adult height in individuals of african ancestry

Adult height is a classic polygenic trait of high heritability (h ² ∼0.8). More than 180 single nucleotide polymorphisms (SNPs), identified mostly in populations of European descent, are associated with height. These variants convey modest effects and explain ∼10% of the variance in height. Discovery efforts in other populations, while limited, have revealed loci for height not previously implicated in individuals of European ancestry. Here, we performed a meta-analysis of genome-wide association (GWA) results for adult height in 20,427 individuals of African ancestry with replication in up to 16,436 African Americans. We found two novel height loci (Xp22-rs12393627, P = 3.4×10⁻¹² and 2p14-rs4315565, P = 1.2×10⁻⁸). As a group, height associations discovered in European-ancestry samples replicate in individuals of African ancestry (P = 1.7×10⁻⁴ for overall replication). Fine-mapping of the European height loci in African-ancestry individuals showed an enrichment of SNPs that are associated with expression of nearby genes when compared to the index European height SNPs (P<0.01). Our results highlight the utility of genetic studies in non-European populations to understand the etiology of complex human diseases and traits.