Magic traits in speciation: 'magic' but not rare?

Speciation with gene flow is greatly facilitated when traits subject to divergent selection also contribute to non-random mating. Such traits have been called 'magic traits', which could be interpreted to imply that they are rare, special, or unrealistic. Here, we question this assumption by illustrating that magic traits can be produced by a variety of mechanisms, including ones in which reproductive isolation arises as an automatic by-product of adaptive divergence. We also draw upon the theoretical literature to explore whether magic traits have a unique role in speciation or can be mimicked in their effects by physically linked trait-complexes. We conclude that magic traits are more frequent than previously perceived, but further work is needed to clarify their importance.     

Immune cross-reactivity in celiac disease: anti-gliadin antibodies bind to neuronal synapsin I

Celiac disease is an immune-mediated disorder triggered by ingestion of wheat gliadin and related proteins in genetically susceptible individuals. In addition to the characteristic enteropathy, celiac disease is associated with various extraintestinal manifestations, including neurologic complications such as neuropathy, ataxia, seizures, and neurobehavioral changes. The cause of the neurologic manifestations is unknown, but autoimmunity resulting from molecular mimicry between gliadin and nervous system proteins has been proposed to play a role. In this study, we sought to investigate the immune reactivity of the anti-gliadin Ab response toward neural proteins. We characterized the binding of affinity-purified anti-gliadin Abs from immunized animals to brain proteins by one- and two-dimensional gel electrophoresis, immunoblotting, and peptide mass mapping. The major immunoreactive protein was identified as synapsin I. Anti-gliadin Abs from patients with celiac disease also bound to the protein. Such cross-reactivity may provide clues into the pathogenic mechanism of the neurologic deficits that are associated with gluten sensitivity.     

Protein-liposome conjugates using cysteine-lipids and native chemical ligation

Liposomes have become popular drug delivery vehicles and have more recently also been applied as contrast agents for molecular imaging. Most current methods for functionalization of liposomes with targeting proteins rely on reactions of amine or thiol groups at the protein exterior, which generally result in nonspecific conjugation at multiple sites on the protein. In this study, we present native chemical ligation (NCL) as a general method to covalently couple recombinant proteins in a highly specific and chemoselective way to liposomes containing cysteine-functionalized phospholipids. A cysteine-functionalized phospholipid (Cys-PEG-DSPE) was prepared and shown to readily react with the MESNA thioester of EYFP, which was used as a model protein. Characterization of the EYFP-liposomes using fluorescence spectroscopy showed full retention of the fluorescent properties of conjugated EYFP and provides a lower limit of 120 proteins per liposome. The general applicability of NCL was further tested using CNA35, a collagen-binding protein recently applied in fluorescent imaging of collagen. NCL of CNA35 thioester yielded liposomes containing approximately 100 copies of CNA35 per liposome. The CNA35-liposomes were shown to be fully functional and bind collagen with a 150-fold higher affinity compared to CNA35. Our results show that NCL is an attractive addition to existing conjugation methods that allows direct, covalent, and highly specific coupling of recombinant proteins to liposomes and other lipid-based assemblies.     

New driver for lipid synthesis

Cholesterol regulates activation of sterol regulatory element-binding protein (SREBP) through a classic feedback loop. Walker et al. (2011) extend the regulatory inputs governing SREBP activity to include an independent loop modulated by phosphatidylcholine (PC) and cellular methylation capacity. These findings suggest a link between lipid synthesis and cellular pathways involved in methylation.     

Chlamydia trachomatis: identification of susceptibility markers for ocular and sexually transmitted infection by immunogenetics

The aim of this review is to present a concise overview of all data available on the immunogenetics of Chlamydia trachomatis infections, both sexually transmitted urogenital and ocular infections. Currently, candidate gene approaches are used to identify genes related to the susceptibility to and severity of C. trachomatis infections. The main focus in the review will be on data obtained by the study of human cohorts.