INFLAM – INFLAMmation in Brain and Vessels with Iron Nanoparticles and Cell Trafficking: A Multiscale Approach of Tissue Microenvironment,Iron Nanostructure and Iron Biotransformation

Background

Inflammation is a share process in atherosclerosis and stroke and is thought to be a key player in the evolution of these diseases. Ten years ago, inflammation imaging with magnetic resonance imaging (MRI) was considered very promising for both pre-clinical and clinical studies of atherosclerosis and stroke.

Nonneutral evolution of tandem repeats in the mitochondrial DNA control region of lagomorphs

The mitochondrial DNA of the European rabbit (Oryctolagus cuniculus) contains a tandem array of 153-bp repeats in the vicinity of the replication origin of the H-stand. Variation among molecules in the number of these repeats results in inter- and intraindividual length polymorphism (heteroplasmy). Generally, in an individual, one predominant molecular type is observed, the others representing a low percentage of the mtDNA content. At the tissue level, we observe a particular distribution of this polymorphism in the gonads compared with liver, kidneys, or brain, implying a relationship between the differentiation status of the cells and the types of new mtDNA molecules which appear and accumulate during lifetime. Similar tandem repeats were also found in the mtDNA noncoding region of European hares (Lepus europaeus), a cottontail (Sylvilagus floridanus), and a pika (Ochotona rufescens). The lengths and the sequences of these units evolve rapidly and in a concerted way, but the number of repeats is maintained in a narrow range, and an internal 20-bp segment is highly conserved. Constraints restrict the evolution of the primary sequence of these repeated units, the number of which is probably controlled by a stabilizing selection.      

Allosteric-type control of synaptobrevin cleavage by protect tetanus toxin light chain

Summary The light chain of tetanus neurotoxin (TeNTL chain) has been shown to be endowed with zine endopeptidase activity, selectively directed towards the Gln⁷⁶-Phe⁷⁷ bond of synaptobrevin, a vesicle-associated membrane protein critically involved in neuroexocytosis. In previous reports, truncations at the NH₂- and COOH-terminus of synaptobrevin have shown that the sequence 39–88 of synaptobrevin is the minimum substrate of TeNT, suggesting either the requirement of a well-defined three-dimensional structure of synaptobrevin or a role in the mechanism of substrate hydrolysis for residues distal from the cleavage site. In this study, the addition of NH₂- and COOH-terminal peptides of synaptobrevin, S 27–55 (S₁) and S 82–93 (S₂), to the synaptobrevin fragment S 56–81 allowed the cleavage of this latter peptide by TeNT to occur. This appears to result from an activation process mediated by the simultaneous binding of S₁ and S₂ with complementary sites present on TeNT as shown by surface plasmon resonance experiments. All these results favor an exosite-controlled hydrolysis of synaptobrevin by TeNT probably involving a conformational change of the toxin. This could accound for the high degree of substrate specificity of TeNT and, probably, botulinum neurotoxins.     

DNA binding properties of a chemically synthesized DNA binding domain of hRFX1.

The RFX DNA binding domain (DBD) is a novel highly conserved motif belonging to a large number of dimeric DNA binding proteins which have diverse regulatory functions in eukaryotic organisms, ranging from yeasts to human. To characterize this novel motif, solid phase synthesis of a 76mer polypeptide corresponding to the DBD of human hRFX1 (hRFX1/DBD), a prototypical member of the RFX family, has been optimized to yield large quantities (approximately 90 mg) of pure compound. Preliminary two-dimensional1H NMR experiments suggested the presence of helical regions in this sequence in agreement with previously reported secondary structure predictions. In gel mobility shift assays, this synthetic peptide was shown to bind in a cooperative manner the 23mer duplex oligodeoxynucleotide corresponding to the binding site of hRFX1, with a 2:1 stoichoimetry due to an inverse repeat present in the 23mer. The stoichiometry of this complex was reduced to 1:1 by decreasing the length of the DNA sequence to a 13mer oligonucleotide containing a single half-site. Surface plasmon resonance measurements were achieved using this 5'-biotylinated 13mer oligonucleotide immobilized on an avidin-coated sensor chip. Using this method an association constant (K a = 4 x 10(5)/M/s), a dissociation constant (K d = 6 x 10(-2)/s) and an equilibrium dissociation constant (K D = 153 nM) were determined for binding of hRFX1/DBD to the double-stranded 13mer oligonucleotide. In the presence of hRFX1/DBD the melting temperature of the 13mer DNA was increased by 16 degreesC, illustrating stabilization of the double-stranded conformation induced by the peptide.     

Haplotyping cryptic Adélie penguin taxa using low-cost,high-resolution melt curves

Distinguishing morphologically cryptic taxa, by definition, requires genetic data such as DNA sequences. However, DNA sequences may not be obtained easily for taxa from remote sites. Here we provide the details of a high-resolution melt-curve-based method using taxon-specific primers that can distinguish two taxa of Adélie penguins, and that will be usable in Antarctica when combined with some of the newly developed field-deployable thermal cyclers. We suggest that the wider adoption of field-deployable polymerase-chain-reaction-based techniques will enable faster assignation of haplotype to individuals in situ, and so allow the targeting of observations and sample collection to specimens relevant to the research question. Targeting individuals will also reduce the need to repeatedly handle animals and reduce the time and travel required to complete field work.     

Cryptic Exons as a Source of Increased Diversity of Ewing Tumor-Associated EWS–FLI1 Chimeric Products

In the Ewing family of tumors (EFT), the EWS gene is rearranged with members of the ets oncogene family. Variability in genomic breakpoint locations is the source of significant heterogeneity in fusion product structure. As a consequence of variably included exon sequences from the two partner genes, a variable amount of additional peptide sequence is inserted in between the minimal transforming domains. Some of this molecular diversity has recently been correlated with disparate clinical outcome. Here we report on cryptic exons found in the chimeric RNA of three EFT with different EWS-FLI1 fusions. In two tumors, the emergence of a cryptic exon from FLI1 intron 5 in the chimeric RNA was apparently unrelated to the genomic rearrangement that occurred in FLI1 introns 4 and 5, respectively. In one case, a novel exon was generated through the creation of an artificial splice acceptor site in FLI1 intron 6 by the genomic rearrangement that occurred in EWS intron 8. These results further extend the spectrum of molecular diversity in EFT.