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- Howe, B., et al.
(author)
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Growth and physical properties of epitaxial metastable Hf1 - xAlxN alloys deposited on MgO(001) by ultrahigh vacuum reactive magnetron sputtering
- 2007
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In: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 202:4-7, s. 809-814
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Journal article (peer-reviewed)abstract
- Epitaxial metastable Hf1 - xAlxN alloys with 0 ≤ x ≤ 0.50 were grown on MgO(001) substrates at 600 °C by ultrahigh vacuum reactive magnetron sputtering from Hf and Al targets in 90% Ar + 10% N2 discharges at 7 mTorr. X-Ray diffraction and cross-sectional transmission electron microscopy show that Hf1 - xAlxN alloys are single crystals with the B1-NaCl structure. Rutherford backscattering spectroscopy investigations reveal that all films are slightly overstochiometric with N / (Hf + Al) = 1.05 ± 0.05. The relaxed lattice parameter decreased linearly from 0.4519 nm with x = 0 to 0.4438 nm with x = 0.50, compared to 0.4320 nm expected from the linear Vegard's rule. We find a metastable single phase field that is remarkably broad given the large lattice mismatch (≃ 9%) between the two alloy components. Alloying HfN with AlN leads to an increase in hardness (≃ 30% to 32.4 ± 0.7 GPa), as well as nanostructured compositional modulations due to the onset of spinodal decomposition. © 2007 Elsevier B.V. All rights reserved.
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- Kikuta, H, et al.
(author)
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Genomic regulatory blocks encompass multiple neighboring genes and maintain conserved synteny in vertebrates
- 2007
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In: Genome research. - : Cold Spring Harbor Laboratory. - 1088-9051. ; 17:5, s. 545-555
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Journal article (peer-reviewed)abstract
- We report evidence for a mechanism for the maintenance of long-range conserved synteny across vertebrate genomes. We found the largest mammal-teleost conserved chromosomal segments to be spanned by highly conserved noncoding elements (HCNEs), their developmental regulatory target genes, and phylogenetically and functionally unrelated “bystander” genes. Bystander genes are not specifically under the control of the regulatory elements that drive the target genes and are expressed in patterns that are different from those of the target genes. Reporter insertions distal to zebrafish developmental regulatory genes pax6.1/2, rx3, id1, and fgf8 and miRNA genes mirn9-1 and mirn9-5 recapitulate the expression patterns of these genes even if located inside or beyond bystander genes, suggesting that the regulatory domain of a developmental regulatory gene can extend into and beyond adjacent transcriptional units. We termed these chromosomal segments genomic regulatory blocks (GRBs). After whole genome duplication in teleosts, GRBs, including HCNEs and target genes, were often maintained in both copies, while bystander genes were typically lost from one GRB, strongly suggesting that evolutionary pressure acts to keep the single-copy GRBs of higher vertebrates intact. We show that loss of bystander genes and other mutational events suffered by duplicated GRBs in teleost genomes permits target gene identification and HCNE/target gene assignment. These findings explain the absence of evolutionary breakpoints from large vertebrate chromosomal segments and will aid in the recognition of position effect mutations within human GRBs.
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| 6. |
- Laurie, K. L., et al.
(author)
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Cell-specific and efficient expression in mouse and human B cells by a novel hybrid immunoglobulin promoter in a lentiviral vector
- 2007
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In: Gene Therapy. - : Springer Science and Business Media LLC. - 0969-7128 .- 1476-5462. ; 14:23, s. 1623-1631
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Journal article (peer-reviewed)abstract
- The expression of genes specifically in B cells is of great interest in both experimental immunology as well as in future clinical gene therapy. We have constructed a novel enhanced B cell-specific promoter (Igk- E) consisting of an immunoglobulin kappa (Igk) minimal promoter combined with an intronic enhancer sequence and a 30 enhancer sequence from Ig genes. The Igk- E promoter was cloned into a lentiviral vector and used to control expression of enhanced green fluorescent protein (eGFP). Transduction of murine B-cell lymphoma cell lines and activated primary splenic B cells, with IgK-E-eGFP lentivirus, resulted in expression of eGFP, as analysed by flow cytometry, whereas expression in non-B cells was absent. The specificity of the promoter was further examined by transducing Lin bone marrow with Igk-E-eGFP lentivirus and reconstituting lethally irradiated mice. After 16 weeks flow cytometry of lymphoid tissues revealed eGFP expression by CD19(+) cells, but not by CD3(+), CD11b(+), CD11c(+) or Gr-1(+) cells. CD19(+) cells were comprised of both marginal zone B cells and recirculating follicular B cells. Activated human peripheral mononuclear cells were also transduced with Igk-E-eGFP lentivirus under conditions of selective B-cell activation. The Igk-E promoter was able to drive expression of eGFP only in CD19(+) cells, while eGFP was expressed by both spleen focus forming virus and cytomegalovirus constitutive promoters in CD19(+) and CD3(+) lymphocytes. These data demonstrate that in these conditions the Igk-E promoter is cell specific and controls efficient expression of a reporter protein in mouse and human B cells in the context of a lentiviral vector.
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