Characterization of the Interaction between the Chlamydial Adhesin OmcB and the Human Host Cell

In a previous study, we reported that the OmcB protein from Chlamydia pneumoniae mediates adhesion of the infectious elementary body to human HEp-2 cells by interacting with heparin/heparan sulfate-like glycosaminoglycans (GAGs) via basic amino acids located in the first of a pair of XBBXBX heparin-binding motifs (K. Moelleken and J. H. Hegemann, Mol. Microbiol. 67:403–419, 2008). In the present study, we show that the basic amino acid at position 57 (arginine) in the first XBBXBX motif, the basic amino acid at position 61 (arginine) in the second motif, and another amino acid (lysine 69) C terminal to it play key roles in the interaction. In addition, we show that discrimination between heparin-dependent and -independent adhesion by C. trachomatis OmcBs is entirely dependent on three variable amino acids in the so-called variable domain C terminal to the conserved XBBXBX motif. Here, the predicted conformational change in the secondary structure induced by the proline at position 66 seems to be crucial for heparin recognition. Finally, we performed neutralization experiments using different anti-heparan sulfate antibodies to gain insight into the nature of the GAGs recognized by OmcB. The results suggest that C. trachomatis serovar L2 OmcB interacts with 6-O-sulfated domains of heparan sulfate, while C. pneumoniae OmcB apparently interacts with domains of heparan sulfate harboring a diverse subset of O-sulfations.     

The diet of Little Owls Athene noctua in Gloucestershire,England

Capsule Little Owls take a wide variety of food, most of which is made up of earthworms, but also includes bats.     

Provisioning with cereal grain depresses the body condition of insectivorous Yellowhammer Emberiza citrinella nestlings

Capsule The body condition of nestling Yellowhammers was negatively correlated with the amount of cereal grain in the diet. This supports the hypothesis that cereal grain is an inferior nestling food relative to invertebrates. Cereal grain is frequently provisioned to nestlings in a range of bunting species breeding on farmland, suggesting that invertebrates may be limiting in these habitats.     

Shadow enhancers flanking the HoxB cluster direct dynamic Hox expression in early heart and endoderm development

The products of Hox genes function in assigning positional identity along the anterior–posterior body axis during animal development. In mouse embryos, Hox genes located at the 3′ end of HoxA and HoxB complexes are expressed in nested patterns in the progenitors of the secondary heart field during early cardiogenesis and the combined activities of both of these clusters are required for proper looping of the heart. Using Hox bacterial artificial chromosomes (BACs), transposon reporters, and transgenic analyses in mice, we present the identification of several novel enhancers flanking the HoxB complex which can work over a long range to mediate dynamic reporter expression in the endoderm and embryonic heart during development. These enhancers respond to exogenously added retinoic acid and we have identified two retinoic acid response elements (RAREs) within these control modules that play a role in potentiating their regulatory activity. Deletion analysis in HoxB BAC reporters reveals that these control modules, spread throughout the flanking intergenic region, have regulatory activities that overlap with other local enhancers. This suggests that they function as shadow enhancers to modulate the expression of genes from the HoxB complex during cardiac development. Regulatory analysis of the HoxA complex reveals that it also has enhancers in the 3′ flanking region which contain RAREs and have the potential to modulate expression in endoderm and heart tissues. Together, the similarities in their location, enhancer output, and dependence on retinoid signaling suggest that a conserved cis-regulatory cassette located in the 3′ proximal regions adjacent to the HoxA and HoxB complexes evolved to modulate Hox gene expression during mammalian cardiac and endoderm development. This suggests a common regulatory mechanism, whereby the conserved control modules act over a long range on multiple Hox genes to generate nested patterns of HoxA and HoxB expression during cardiogenesis.     

Benzoic acid and specific 2-oxo acids activate hepatic efflux of glutamate at OAT2

The liver is the principal source of glutamate in blood plasma. Recently we have discovered that efflux of glutamate from hepatocytes is catalyzed by the transporter OAT2 (human gene symbol SLC22A7). Organic anion transporter 2 (OAT2) is an integral membrane protein of the sinusoidal membrane domain; it is primarily expressed in liver and much less in kidney, both in rats and humans. Many years ago, Häussinger and coworkers have demonstrated in isolated perfused rat liver that benzoic acid or specific 2-oxo acid analogs of amino acids like e.g. 2-oxo-4-methyl-pentanoate (‘2-oxo-leucine’) strongly stimulate release of glutamate (up to 7-fold); ‘2-oxo-valine’ and the corresponding amino acids were without effect. The molecular mechanism of efflux stimulation has remained unclear. In the present study, OAT2 from human and rat were heterologously expressed in 293 cells. Addition of 1 mmol/l benzoic acid to the external medium increased OAT2-specific efflux of glutamate up to 20-fold; ‘2-oxo-leucine’ was also effective, but not ‘2-oxo-valine’. Similar effects were seen for efflux of radiolabeled orotic acid. Expression of OAT2 did not increase uptake of benzoic acid; thus, benzoic acid is no substrate, and trans-stimulation can be excluded. Instead, further experiments suggest that increased efflux of glutamate is caused by direct interaction of benzoic acid and specific 2-oxo acids with OAT2. We propose that stimulators bind to a distinct extracellular site and thereby accelerate relocation of the empty substrate binding site to the intracellular face. Increased glutamate efflux at OAT2 could be the main benefit of benzoate treatment in patients with urea cycle defects.     

Design and synthesis of MMP inhibitors with appended fluorescent tags for imaging and visualization of matrix metalloproteinase enzymes

We describe the synthesis, MMP-2 and 9 potency, and in vitro evaluation of a series of α-sulfone hydroxmate MMP inhibitors conjugated to a series of dyes with different absorption/emission lamina maxima’s that can be used to visualize tumors.     

Design,synthesis and structure–activity relationships of zwitterionic spirocyclic compounds as potent CCR1 antagonists

A series of zwitterionic spirocyclic compounds were synthesised. In vitro data revealed that these compounds were potent CCR1 antagonists. In particular, 2, 4, 11 and 20 inhibited CCR1 mediated chemotaxis of THP-1 cells in a functional assay.