A girl with karyotype 46,XX,del(7) (qter→p15:)

Summary A girl with partial deletion of the short arms of one chromosome 7 is described. Among many other symptoms she has craniosynostosis. Early closure of cranio-sutures has previously been described in 2 of 3 patients with partial deletion 7. Investigation of a number of genetic marker systems shows that the HL-A, MN, AcP, and GPT loci are not located in the deleted segment.

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Zusammenfassung Es wird ein Mädchen mit teilweiser Deletion des kurzen Armes eines Chromosoms 7 beschrieben. Außer vielen anderen Symptomen hat sie eine Craniosynostose. Frühzeitiger Verschluß der Schädelnähte wurde auch bei 2 von 3 Patienten mit Deletion 7, die in der Literatur beschrieben sind, beobachtet. Untersuchung einer Reihe genetischer Markersysteme zeigt, daß die HL-A-, MN-, AcP- und GPT-loci nicht in dem deletierten Segment liegen.

     

LNA guanine and 2,6-diaminopurine. Synthesis, characterization and hybridization properties of LNA 2,6-diaminopurine containing oligonucleotides

LNA guanine and 2,6-diaminopurine (D) phosphoramidites have been synthesized as building blocks for antisense oligonucleotides (ON). The effects of incorporating LNA D into ON were investigated. As expected, LNA D containing ON showed increased affinity towards complementary DNA (Delta Tm +1.6 to +3.0 degrees C) and RNA (Delta Tm +2.6 to +4.6 degrees C) ON. To evaluate if LNA D containing ON have an enhanced mismatch sensitivity compared to their complementary LNA A containing ON thermal denaturation experiments towards singly mismatched DNA and RNA ON were undertaken. Replacing one LNA A residue with LNA D, in fully LNA modified ON, resulted in higher mismatch sensitivity towards DNA ON (Delta Delta Tm -4 to >-17 degrees C). The same trend was observed towards singly mismatched RNA ON (Delta Delta Tm D-a = -8.7 degrees C and D-g = -4.5 degrees C) however, the effect was less clearcut and LNA A showed a better mismatch sensitivity than LNA D towards cytosine (Delta Tm +5.5 degrees C).     

Thermodynamic and biological evaluation of a thrombin binding aptamer modified with several unlocked nucleic acid (UNA) monomers and a 2'-C-piperazino-UNA monomer

Thrombin binding aptamer is a DNA 15-mer which forms a G-quadruplex structure and possess promising anticoagulant properties due to specific interactions with thrombin. Herein we present the influence of a single 2'-C-piperazino-UNA residue and UNA residues incorporated in several positions on thermodynamics, kinetics and biological properties of the aptamer. 2'-C-Piperazino-UNA is characterized by more efficient stabilization of quadruplex structure in comparison to regular UNA and increases thermodynamic stability of TBA by 0.28-0.44 kcal/mol in a position depending manner with retained quadruplex topology and molecularity. The presence of UNA-U in positions U3, U7, and U12 results in the highest stabilization of G-quadruplex structure (ΔΔG(37)(°)=-1.03kcal/mol). On the contrary, the largest destabilization mounting to 1.79 kcal/mol was observed when UNA residues were placed in positions U7, G8, and U9. Kinetic studies indicate no strict correlation between thermodynamic stability of modified variants and their binding affinity to thrombin. Most of the studied variants bind thrombin, albeit with decreased affinity in reference to unmodified TBA. Thrombin time assay studies indicate three variants as being as potent as TBA in fibrin clotting inhibition.     

Exploiting the role of endogenous lymphoid-resident dendritic cells in the priming of NKT cells and CD8+ T cells to dendritic cell-based vaccines

Transfer of antigen between antigen-presenting cells (APCs) is potentially a physiologically relevant mechanism to spread antigen to cells with specialized stimulatory functions. Here we show that specific CD8+ T cell responses induced in response to intravenous administration of antigen-loaded bone marrow-derived dendritic cells (BM-DCs), were ablated in mice selectively depleted of endogenous lymphoid-resident langerin+ CD8α+ dendritic cells (DCs), suggesting that the antigen is transferred from the injected cells to resident APCs. In contrast, antigen-specific CD4+ T cells were primed predominantly by the injected BM-DCs, with only very weak contribution of resident APCs. Crucially, resident langerin+ CD8α+ DCs only contributed to the priming of CD8+ T cells in the presence of maturation stimuli such as intravenous injection of TLR ligands, or by loading the BM-DCs with the glycolipid α-galactosylceramide (α-GalCer) to recruit the adjuvant activity of activated invariant natural killer-like T (iNKT) cells. In fact, injection of α-GalCer-loaded CD1d-/- BM-DCs resulted in potent iNKT cell activation, suggesting that this glycolipid antigen can also be transferred to resident CD1d+ APCs. While iNKT cell activation per se was independent of langerin+ CD8α+ DCs, some iNKT cell-mediated activities were reduced, notably release of IL-12p70 and transactivation of NK cells. We conclude that both protein and glycolipid antigens can be exchanged between distinct DC species. These data suggest that the efficacy of DC-based vaccination strategies may be improved by the incorporation of a systemic maturation signal aimed to engage resident APCs in CD8+ T cell priming, and α-GalCer may be particularly well suited to this purpose.     

Juvenile songbirds compensate for displacement to oceanic islands during autumn migration

To what degree juvenile migrant birds are able to correct for orientation errors or wind drift is still largely unknown. We studied the orientation of passerines on the Faroe Islands far off the normal migration routes of European migrants. The ability to compensate for displacement was tested in naturally occurring vagrants presumably displaced by wind and in birds experimentally displaced 1100 km from Denmark to the Faroes. The orientation was studied in orientation cages as well as in the free-flying birds after release by tracking departures using small radio transmitters. Both the naturally displaced and the experimentally displaced birds oriented in more easterly directions on the Faroes than was observed in Denmark prior to displacement. This pattern was even more pronounced in departure directions, perhaps because of wind influence. The clear directional compensation found even in experimentally displaced birds indicates that first-year birds can also possess the ability to correct for displacement in some circumstances, possibly involving either some primitive form of true navigation, or 'sign posts', but the cues used for this are highly speculative. We also found some indications of differences between species in the reaction to displacement. Such differences might be involved in the diversity of results reported in displacement studies so far.     

Chemistry of locked nucleic acids (LNA): Design, synthesis, and bio-physical properties

Summary Preparation of LNA nucleosides requires a number of synthetic steps but very efficient procedures have been developed, as have protocols for synthesis of LNA oligonucleotides on automated DNA synthesizers. In all cases, LNA oligonucleotides have exhibited good aqueous solubility as would be expected from their close structural resemblance to the natural nucleic acids. The universality of LNA mediated high-affinity and specific hybridization has been demonstrated extensively with a large number of duplex forming LNA-oligonucleotides. Most importantly, most of the members of the LNA molecular family have been shown to exert their substantial affinity increase (i) in combination with standard DNA, RNA and contemporary analogues and (ii) whether inserted as single nucleosides in an oligonucleotide or as blocks of contiguous nucleotides, an important point. The works on TFOs is expanding the usefulness of LNA to double strand recognition and it has been demonstrated that LNA it is a promising structure for further base modifications in the pursuit of global sequence specific recognition of DNA.     

Non-enzymatic palladium recovery on microbial and synthetic surfaces

The use of microorganisms as support for reduction of dissolved Pd(II) to immobilized Pd(0) nanoparticles is an environmentally friendly approach for Pd recovery from waste. To better understand and engineer Pd(0) nanoparticle synthesis, one has to consider the mechanisms by which Pd(II) is reduced on microbial surfaces. Escherichia coli, Shewanella oneidensis, and Pseudomonas putida were used as model organisms in order to elucidate the role of microbial cells in Pd(II) reduction under acidic conditions. Pd(II) was reduced by formate under acidic conditions, and the process occurred substantially faster in the presence of cells as compared to cell-free controls. We found no difference between native (untreated) and autoclaved cells, and could demonstrate that even a non-enzymatic protein (bovine serum albumin) stimulated Pd(II) reduction as efficiently as bacterial cells. Amine groups readily interact with Pd(II), and to specifically test their role in surface-assisted Pd(II) reduction by formate, we replaced bacterial cells with polystyrene microparticles functionalized with amine or carboxyl groups. Amine-functionalized microparticles had the same effect on Pd(II) reduction as bacterial cells, and the effect could be hampered if the amine groups were blocked by acetylation. The interaction with amine groups was confirmed by infrared spectroscopy on whole cells and amine-functionalized microparticles. In conclusion, bio-supported Pd(II) reduction on microbial surfaces is possibly mediated by a non-enzymatic mechanism. We therefore suggest the use of amine-rich biomaterials rather than intact cells for Pd bio-recovery from waste.     

Modulation of fibrillation of hIAPP core fragments by chemical modification of the peptide backbone

The well-ordered cross β-strand structure found in amyloid aggregates is stabilized by many different side chain interactions, including hydrophobic interactions, electrostatic charge and the intrinsic propensity to form β-sheet structures. In addition to the side chains, backbone interactions are important because of the regular hydrogen-bonding pattern. β-Sheet breaking peptide analogs, such as those formed by N-methylation, interfere with the repetitive hydrogen bonding pattern of peptide strands. Here we test backbone contributions to fibril stability using analogs of the 6-10 residue fibril core of human islet amyloid polypeptide, a 37 amino acid peptide involved in the pathogenesis of type II diabetes. The Phe-Gly peptide bond has been replaced by a hydroxyethylene or a ketomethylene group and the nitrogen-atom has been methylated. In addition, we have prepared peptoids where the side chain is transferred to the nitrogen atom. The backbone turns out to be extremely sensitive to substitution, since only the minimally perturbed ketomethylene analog (where only one of the -NH- groups has been replaced by -CH(2)-) can elongate wildtype fibrils but cannot fibrillate on its own. The resulting fibrils displayed differences in both secondary structure and overall morphology. No analog could inhibit the fibrillation of the parent peptide, suggesting an inability to bind to existing fibril surfaces. In contrast, side chain mutations that left the backbone intact but increased backbone flexibility or removed stabilizing side-chain interactions had very small effect on fibrillation kinetics. We conclude that fibrillation is very sensitive to even small modifications of the peptide backbone.