| 51. |
|
|
| 52. |
- Los, Marek Jan, et al.
(författare)
-
Requirement of an Ice/Ced-3 Protease for Fas/Apo-1-Mediated Apoptosis
- 1995
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 375:6526, s. 81-83
-
Tidskriftsartikel (refereegranskat)abstract
- THE Fas/APO-1 receptor is one of the major regulators of apoptosis(1-7). We report here that Fas/APO-1-mediated apoptosis requires the activation of a new class of cysteine proteases, including interleukin-1 beta-converting enzyme (ICE)(8-10) which are homologous to the product of the Caenorhabditis elegans cell-death gene ced-3 (refs 11, 12). Triggering of Fas/APO-1 rapidly stimulated the proteolytic activity of ICE. Overexpression of ICE, achieved by electroporation and microinjection, strongly potentiated Fas/APO-1-mediated cell death. In addition, inhibition of ICE activity by protease inhibitors, as well as by transient expression of the pox virus-derived serpin inhibitor CrmA or an antisense ICE construct, substantially suppressed Fas/APO-1-triggered cell death. We conclude that activation of ICE or an ICE-related protease is a critical event in Fas/APO-1-mediated cell death.
|
|
| 53. |
- Lundström, Ingemar, et al.
(författare)
-
Artificial 'olfactory' images from a chemical sensor using a light-pulse technique
- 1991
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 352:6330, s. 47-50
-
Tidskriftsartikel (refereegranskat)abstract
- THERE is much interest in the use of chemical sensor arrays, in conjunction with pattern-recognition routines, for developing artificial olfactory devices-electronic noses-which can characterize the chemical composition of gas mixtures 1-5. Here we describe a technique that uses a continuous sensing surface and a detection method involving a scanning pulsed light source, to generate images that represent a fingerprint of the gases detected. The detector is a large-area field-effect device with a number of different catalytic metals constituting the detecting surface (the devices active gate) 6,7. A pulsed light beam scanned across this surface generates a photocapacitive current that varies with the value of the surface potential 8,9. A continuous sensing surface of this type provides information that would require an array of hundreds of discrete sensors. The technique also provides a new means of studying the coupling between the electronic properties of catalytic metals and chemical reactions taking place on their surfaces.
|
|
| 54. |
|
|
| 55. |
- Magnusson, PKE, et al.
(författare)
-
Genetic link to cervical tumours
- 1999
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 400:6739, s. 29-30
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 56. |
- Marcaide, J. M., et al.
(författare)
-
Discovery of shell-like radio-structure in SN1993J
- 1995
-
Ingår i: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 373:6509, s. 44-45
-
Tidskriftsartikel (refereegranskat)abstract
- SUPERNOVA explosions are poorly understood, partly because of difficulties in modelling them theoretically(1), and partly because there have been no supernovae observed in our Galaxy since the invention of the telescope. But the recent discovery(2) of supernova SN1993J in the nearby galaxy M81 offers an opportunity to investigate the evolution of the remnant, and its interaction with the surrounding interstellar medium, at high resolution. Here we present radio observations of SN1993J, made using very-long-baseline interferometry, which show the development of a shell structure. This 8-month-old radio shell is the youngest ever discovered in a supernova. The data suggest that the supernova explosion and the expanding shell of the remnant have nearly spherical symmetry, with small deviations where some parts of the shell are brighter than others. If these deviations arise because of variations in the density of the shell, this may reconcile earlier reports of symmetric radio emission(3) with the observed optical asymmetry(4,5), as the density variations could easily cause the latter. We infer that the radio emission is generated at the interface(6-9), where the surrounding gas is shocked by the ejecta.
|
|
| 57. |
|
|
| 58. |
- Novak, R, et al.
(författare)
-
Emergence of vancomycin tolerance in Streptococcus pneumoniae.
- 1999
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 399:6736, s. 590-593
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae, the pneumococcus, is the most common cause of sepsis and meningitis. Multiple-antibiotic-resistant strains are widespread, and vancomycin is the antibiotic of last resort. Emergence of vancomycin resistance in this community-acquired bacterium would be catastrophic. Antibiotic tolerance, the ability of bacteria to survive but not grow in the presence of antibiotics, is a precursor phenotype to resistance. Here we show that loss of function of the VncS histidine kinase of a two-component sensor-regulator system in S. pneumoniae produced tolerance to vancomycin and other classes of antibiotic. Bacterial two-component systems monitor environmental parameters through a sensor histidine-kinase/phosphatase, which phosphorylates/dephosphorylates a response regulator that in turn mediates changes in gene expression. These results indicate that signal transduction is critical for the bactericidal activity of antibiotics. Experimental meningitis caused by the vncS mutant failed to respond to vancomycin. Clinical isolates tolerant to vancomycin were identified and DNA sequencing revealed nucleotide alterations in vncS. We conclude that broad antibiotic tolerance of S. pneumoniae has emerged in the community by a molecular mechanism that eliminates sensitivity to the current cornerstone of therapy, vancomycin.
|
|
| 59. |
- Näsholm, Torgny, et al.
(författare)
-
Boreal forest plants take up organic nitrogen
- 1998
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 392:6679, s. 914-916
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Plant growth in the boreal forest, the largest terrestrial biome, is generally limited by the availability of nitrogen. The presumed cause of this limitation is slow mineralization of soil organic nitrogen1,2. Here we demonstrate, to our knowledge for the first time, the uptake of organic nitrogen in the field by the trees Pinus sylvestris and Picea abies, the dwarf shrub Vaccinium myrtillus and the grass Deschampsia flexuosa. These results show that these plants, irrespective of their different types of root–fungal associations (mycorrhiza), bypass nitrogen mineralization. A trace of the amino acid glycine, labelled with the stable isotopes 13C and 15N, was injected into the organic (mor) layer of an old successional boreal coniferous forest. Ratios of 13C:15N in the roots showed that at least 91, 64 and 42% of the nitrogen from the absorbed glycine was taken up in intact glycine by the dwarf shrub, the grass and the trees, respectively. Rates of glycine uptake were similar to those of 15N-ammonium. Our data indicate that organic nitrogen is important for these different plants, even when they are competing with each other and with non-symbiotic microorganisms. This has major implications for our understanding of the effects of nitrogen deposition, global warming and intensified forestry.
|
|
| 60. |
|
|
