| 1. |
- Chen, J., et al.
(author)
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Generation of normal T and B lymphocytes by c-jun deficient embryonic stem cells
- 1994
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In: Immunity. - : Cell Press. - 1074-7613 .- 1097-4180. ; 1:1, s. 65-72
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Journal article (peer-reviewed)abstract
- To determine the potential roles of c-jun in lymphocyte development, we generated somatic chimeric mice by injecting homozygous c-jun mutant embryonic stem (ES) cells into blastocysts from recombination activating gene-2 (RAG-2)-deficient mice. Chimeric mice had poor restoration of thymocytes, but contained substantial numbers of mature T and B lymphocytes in the periphery. Stimulation of c-jun-/- B cells resulted in normal levels of proliferation and immunoglobulin secretion. Likewise, stimulation of c-jun-/- T cells resulted in essentially normal levels of IL-2R alpha expression, IL-2 secretion, and proliferation. We further showed that the relatively normal activation responses of the c-jun-/- T cells probably results from the fact that other members of the Jun family contribute to the bulk of the activator protein-1 (AP-1) complexes in normal T cells and, as a result, AP-1 complexes are found at relatively normal levels in c-jun-/- T cells.
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| 2. |
- Penston, M. V., et al.
(author)
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The extended narrow line region of NGC 4151. I. Emission line ratios and their implications
- 1990
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 236:1, s. 53-6262
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Journal article (peer-reviewed)abstract
- The paper presents the first results from long-slit spectra of the Seyfert galaxy NGC 4151 which give average diagnostic ratios of weak lines in the extended narrow line region (ENLR) of that galaxy and the first direct density measurement in an ENLR. These data confirm that the ENLR is kinematically undisturbed gas in the disc of the galaxy which is illuminated by an ionizing continuum stronger by a factor of 13 than a power law interpolated between observed ultraviolet and X-ray fluxes. Explanations of this apparent excess include a hot thermal continuum, time variations and an anisotropic radiation field. The authors give reasons for favouring anisotropy which might be caused by shadowing by a thick accretion disc or by relativistic beaming. Shadowing by a molecular torus is unlikely, given the absence of an infrared signal from the reradiated flux absorbed by any torus. Anisotropy would have important implications for the bolometric luminosity and nature of active galactic nuclei
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| 3. |
- Pritchard, R E, et al.
(author)
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Bonding of H-CAs pairs in AlxGa1-xAs alloys
- 1994
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 50:15, s. 10628-10636
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Journal article (peer-reviewed)abstract
- The local structure of CAs acceptors in AlxGa1-xAs has been investigated by studying the nondegenerate localized vibrational modes of H-CAs pairs with A1 symmetry, rather than those of isolated CAs impurities. Infrared absorption and Raman scattering measurements have been made on AlxGa1-xAs: 12C epilayers that (a) had been exposed to a radio-frequency hydrogen (deuterium) plasma or (b) contained hydrogen incorporated during growth. Arguments are advanced that indicate that the H(D) atom should occupy a bond-centered site between CAs and Ga atoms rather than between CAs and Al atoms at low temperatures. An ab initio local-density-functional calculation indicates that the energy is then lowered by 0.24 eV. This analysis has led to the assignment of five antisymmetric stretch modes and five symmetric (X) modes to H-CAs pairs at sites where the carbon atom that was originally unpaired had zero, one, two, three, or four Al nearest neighbors
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