Drosophila cohesins DSA1 and Drad21 persist and colocalize along the centromeric heterochromatin during mitosis

Sister chromatid cohesion in eukaryotes is maintained mainly by a conserved multiprotein complex termed cohesin. Drad21 and DSA1 are the Drosophila homologues of the yeast Scc1 and Scc3 cohesin subunits, respectively. We recently identified a Drosophila mitotic cohesin complex composed of Drad21/DSA1/DSMC1/DSMC3. Here we study the contribution of this complex to sister chromatid cohesion using immunofluorescence microscopy to analyze cell cycle chromosomal localization of DSA1 and Drad21 in S2 cells. We observed that DSA1 and Drad21 colocalize during all cell cycle stages in cultured cells. Both proteins remain in the centromere until metaphase, colocalizing at the centromere pairing domain that extends along the entire heterochromatin; the centromeric cohesion protein MEI-S332 is nonetheless reported in a distinct centromere domain. These results provide strong evidence that DSA1 and Drad21 are partners in a cohesin complex involved in the maintenance of sister chromatid arm and centromeric cohesion during mitosis in Drosophila.     

Beiträge zur bakteriensymbiose der ameisen

Ohne Zusammenfassung     

Distribution patterns of the ΔF508 mutation in the CFTR gene on CF-linked marker haplotypes in the German population

Summary We have measured the frequency of the ΔF508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its association with cystic fibrosis (CF)-linked marker haplotypes in the German population. Based on the analysis of 400 CF chromosomes, the frequency of the ΔF508 mutation is estimated to be 77.3%, the vast majority being associated with marker haplotype KM19-XV2c 2 1. Our data further suggest the presence of another frequent CF mutation associated with this marker haplotype.     

Functional characterization of polysaccharide utilization loci in the marine Bacteroidetes ‘Gramella forsetii' KT0803

Members of the phylum Bacteroidetes are abundant in many marine ecosystems and are known to have a pivotal role in the mineralization of complex organic substrates such as polysaccharides and proteins. We studied the decomposition of the algal glycans laminarin and alginate by ‘Gramella forsetii'' KT0803, a bacteroidetal isolate from North Sea surface waters. A combined application of isotope labeling, subcellular protein fractionation and quantitative proteomics revealed two large polysaccharide utilization loci (PULs) that were specifically induced, one by alginate and the other by laminarin. These regulons comprised genes of surface-exposed proteins such as oligomer transporters, substrate-binding proteins, carbohydrate-active enzymes and hypothetical proteins. Besides, several glycan-specific TonB-dependent receptors and SusD-like substrate-binding proteins were expressed also in the absence of polysaccharide substrates, suggesting an anticipatory sensing function. Genes for the utilization of the beta-1,3-glucan laminarin were found to be co-regulated with genes for glucose and alpha-1,4-glucan utilization, which was not the case for the non-glucan alginate. Strong syntenies of the PULs of ‘G. forsetii'' with similar loci in other Bacteroidetes indicate that the specific response mechanisms of ‘G. forsetii'' to changes in polysaccharide availability likely apply to other Bacteroidetes. Our results can thus contribute to an improved understanding of the ecological niches of marine Bacteroidetes and their roles in the polysaccharide decomposition part of carbon cycling in marine ecosystems.     

Genetic Control of Obesity and Gut Microbiota Composition in Response to High-Fat,High-Sucrose Diet in Mice

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Highlights? Detailed analysis of diet-induced obesity in more than 100 inbred mouse strains ? Identification of 11 genetic loci associated with obesity and dietary responsiveness ? Significant overlap between mouse loci with human GWAS loci for obesity ? Strain-specific shifts in gut microbiota composition in response to dietary intervention     

HIF-1α activation results in actin cytoskeleton reorganization and modulation of Rac-1 signaling in endothelial cells

Background

Increasing structural and biochemical evidence suggests that post-translational methionine oxidation of proteins is not just a result of cellular damage but may provide the cell with information on the cellular oxidative status. In addition, oxidation of methionine residues in key regulatory proteins, such as calmodulin, does influence cellular homeostasis. Previous findings also indicate that oxidation of methionine residues in signaling molecules may have a role in stress responses since these specific structural modifications can in turn change biological activities of proteins.

Findings

Here we use tandem mass spectrometry-based proteomics to show that treatment of Arabidopsis thaliana cells with a non-oxidative signaling molecule, the cell-permeant second messenger analogue, 8-bromo-3,5-cyclic guanosine monophosphate (8-Br-cGMP), results in a time-dependent increase in the content of oxidised methionine residues. Interestingly, the group of proteins affected by cGMP-dependent methionine oxidation is functionally enriched for stress response proteins. Furthermore, we also noted distinct signatures in the frequency of amino acids flanking oxidised and un-oxidised methionine residues on both the C- and N-terminus.

Conclusions

Given both a structural and functional bias in methionine oxidation events in response to a signaling molecule, we propose that these are indicative of a specific role of such post-translational modifications in the direct or indirect regulation of cellular responses. The mechanisms that determine the specificity of the modifications remain to be elucidated.     

Pteridine Nucleosides—New Versatile Building Blocks in Oligonucleotide Synthesis

Abstract

Chemical syntheses of 1-(2-deoxy-β-D-ribofuranosyl)lumazines and isopterins as well as 8-(2-deoxy-β-D-ribofuranosyl)-4-amino-7(8H)pteridones and -isoxanthopterins have been developed to make the structural analogs of the naturally occurring 2′-deoxyribonucleosides in the pteridine series available. The corresponding phosphoramidites have been used in machine-aided solid-support syntheses leading to new types of fluorescence labeled oligonucleotides. The effects of the various fluorophors on duplex formation and as labels for enzyme reactions is demonstrated.     

Imaging of specific activation of photodynamic molecular beacons in breast cancer vertebral metastases

Breast cancer is the second leading cause of cancer-related death in women. Approximately 85% of patients with advanced cases will develop spinal metastases. The vertebral column is the most common site of breast cancer metastases, where overexpression of matrix metalloproteinases (MMPs) promotes the spread of cancer. Current therapies have significant limitations due to the high associated risk of damaging the spinal cord. An attractive alternative is photodynamic therapy providing noninvasive and site-selective treatment. However, current photosensitizers are limited by their nonspecific accumulation. Photodynamic molecular beacons (PP(MMP)B), activated by MMPs, offer another level of PDT selectivity and image-guidance preserving criticial tissues, specifically the spinal cord. Metastatic human breast carcinoma cells, MT-1, were used to model the metastatic behavior of spinal lesions. In vitro and in vivo evidence demonstrates MMP specific activation of PP(MMP)B in MT-1 cells. Using a clinically relevant metastatic model, fluorescent imaging establishes the specific activation of PP(MMP)B by vertebral metastases versus normal tissue (i.e., spinal cord) demonstrating the specificity of these beacons. Here, we validate that the metastasis-selective mechanism of PP(MMP)Bs can specifically image breast cancer vertebral metastases, thereby differentiating tumor and healthy tissue.