| 1. |
- Clark, Andrew G., et al.
(författare)
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Evolution of genes and genomes on the Drosophila phylogeny
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
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Tidskriftsartikel (refereegranskat)abstract
- Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
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| 2. |
- Naarding, Marloes A, et al.
(författare)
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Bile salt-stimulated lipase from human milk binds DC-SIGN and inhibits human immunodeficiency virus type 1 transfer to CD4+ T cells.
- 2006
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Ingår i: Antimicrob Agents Chemother. - 0066-4804. ; 50:10, s. 3367-74
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Tidskriftsartikel (refereegranskat)abstract
- A wide range of pathogens, including human immunodeficiency virus type 1 (HIV-1), hepatitis C virus, Ebola virus, cytomegalovirus, dengue virus, Mycobacterium, Leishmania, and Helicobacter pylori, can interact with dendritic cell (DC)-specific ICAM3-grabbing nonintegrin (DC-SIGN), expressed on DCs and a subset of B cells. More specifically, the interaction of the gp120 envelope protein of HIV-1 with DC-SIGN can facilitate the transfer of virus to CD4+ T lymphocytes in trans and enhance infection. We have previously demonstrated that a multimeric LeX component in human milk binds to DC-SIGN, preventing HIV-1 from interacting with this receptor. Biochemical analysis reveals that the compound is heat resistant, trypsin sensitive, and larger than 100 kDa, indicating a specific glycoprotein as the inhibitory compound. By testing human milk from three different mothers, we found the levels of DC-SIGN binding and viral inhibition to vary between samples. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and matrix-assisted laser desorption ionization analysis, we identified bile salt-stimulated lipase (BSSL), a Lewis X (LeX)-containing glycoprotein found in human milk, to be the major variant protein between the samples. BSSL isolated from human milk bound to DC-SIGN and inhibited the transfer of HIV-1 to CD4+ T lymphocytes. Two BSSL isoforms isolated from the same human milk sample showed differences in DC-SIGN binding, illustrating that alterations in the BSSL forms explain the differences observed. These results indicate that variations in BSSL lead to alterations in LeX expression by the protein, which subsequently alters the DC-SIGN binding capacity and the inhibitory effect on HIV-1 transfer. Identifying the specific molecular interaction between the different forms may aid in the future design of antimicrobial agents.
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| 3. |
- Spijksma, Gerald I., et al.
(författare)
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Nona-coordinated MO6N3 centers M = Zr, Hf as a stable building block for the construction of heterometallic alkoxide precursors
- 2007
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693 .- 1873-3255. ; 360:6, s. 2045-2055
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Tidskriftsartikel (refereegranskat)abstract
- The modification of zirconium or hafnium alkoxides with diethanolamine, H(2)dea, leads to the formation of unique nona-coordinated M{mu-eta(3)-NH(C2H4O)(2)}(3) cores. The mechanism is used to develop a self-assembly approach to the first thermodynamically stable zirconium-titanium and hafnium-titanium precursors, Zr{mu-eta(3)-NH(C2H4O)(2)}(3)[Ti((OPr)-Pr-i)(3)](2) (1) and Hf{mu-eta(3)-NH(C2H4O)(2))(3)[Ti((OPr)-Pr-i)(3)](2) (2). Mass spectrometric characterization of these compounds demonstrates their volatility. In addition to the solution stability of these compounds the volatility makes them attractive single source precursors for MOCVD and ALD applications. These precursors are also interesting candidates for application in sol-gel synthesis of microporous materials as the stability of the core prevents self-assembly of ligands on the outer surface of the primary particles formed during the hydrolysis. A n-propoxide analog of 1 can be prepared from zirconium n-propoxide but does not yield any crystalline material. It is demonstrated that 1 can be prepared from [Zr((OPr)-Pr-n)((OPr)-Pr-i)(3) ((PrOH)-Pr-i)](2), however, with a lower yield compared to the use of zirconium isopropoxide. The single crystals obtained from systems containing zirconium isopropoxide, titanium isopropoxide and triethanolamine H(3)tea turned out to be Ti-2((OPr)-Pr-i)(2)(mu-eta(4)-NH(C2H4O)(3)}(2))(2) (4). Theoretical calculations indicate that the octacoordinate M{mu-eta(4)-N(C2H4O)(3)}(2) core, anticipated in reaction with H(3)tea, will have metal-nitrogen bonds that are too long for its stabilization. This explains why the formation of 4 is thermodynamically favored over the formation of heterometallic species.
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| 4. |
- Spijksma, Gerald I., et al.
(författare)
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The molecular composition of non-modified and acac-modified propoxide and butoxide precursors of zirconium and hafnium dioxides
- 2009
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Ingår i: Journal of Sol-Gel Science and Technology. - : Springer Science and Business Media LLC. - 0928-0707 .- 1573-4846. ; 51:1, s. 10-22
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Tidskriftsartikel (refereegranskat)abstract
- Long-term storage at 0 A degrees C of a paraffin-sealed flask with commercial 70 wt% solution of zirconium n-propoxide in n-propanol resulted in crystallization of an individual oxoalkoxide complex Zr(4)O(O(n)Pr)(14)((n)PrOH)(2) in over 20% yield. The structure of this molecule can be described as a triangular Zr(3)(mu(3)-O)(OR)(10)(ROH) core of 3 edge-sharing octahedrons with an additional Zr(OR)(4)(ROH) unit attached through a pair of (mu-OR) bridges. Mass spectrometric and (1)H NMR investigation of the commercial samples of the most broadly applied zirconium and hafnium n-propoxides and n-butoxides indicate the presence of analogous species in the commercial alkoxide precursors. The content of oxo-alkoxide species in the commercial precursors has been estimated to be similar to 20% for n-propoxide and similar to 35% for zirconium n-butoxide. A new route has been presented for synthesis of the individual crystalline mixed ligand precursor [Zr(O(n)Pr)(O(i)Pr)(3)((i)PrOH)](2), from zirconium n-propoxide. A high yield has been observed (similar to 90%), indicative of an almost complete precursor transformation. Mass spectrometry has shown that the synthesized mixed ligand precursor is dimeric, which makes it an attractive alternative to zirconium n-propoxide. Addition of 1 eq of Acetylacetone to zirconium or hafnium alkoxide precursors results in formation of dimeric [M(OR)(3)(acac)](2) in high yields. These species have limited stability (much higher for Hf than for Zr) and transform in solution into hydrolysis-insensitive M(acac)(4) through very unstable M(acac)(3)(OR) intermediates containing 7-coordinated metal centers. This transformation can be followed kinetically in hydrocarbon solvents by (1)H NMR and is noticeably accelerated by addition of parent alcohols. The obtained results clearly reveal limited applicability of EXAFS and XANES techniques for the study of such systems, especially in the context of structure prediction.
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