| 1. |
- Acciari, V. A., et al.
(författare)
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Radio Imaging of the Very-High-Energy gamma-Ray Emission Region in the Central Engine of a Radio Galaxy
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 325:5939, s. 444-448
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Tidskriftsartikel (refereegranskat)abstract
- The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.
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| 2. |
- Bargholtz, Chr., et al.
(författare)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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| 3. |
- Delaney, Joseph R, et al.
(författare)
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Cooperative control of Drosophila immune responses by the JNK and NF-kappaB signaling pathways.
- 2006
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Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 25:13, s. 3068-77
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Tidskriftsartikel (refereegranskat)abstract
- Jun N-terminal kinase (JNK) signaling is a highly conserved pathway that controls both cytoskeletal remodeling and transcriptional regulation in response to a wide variety of signals. Despite the importance of JNK in the mammalian immune response, and various suggestions of its importance in Drosophila immunity, the actual contribution of JNK signaling in the Drosophila immune response has been unclear. Drosophila TAK1 has been implicated in the NF-kappaB/Relish-mediated activation of antimicrobial peptide genes. However, we demonstrate that Relish activation is intact in dTAK1 mutant animals, and that the immune response in these mutant animals was rescued by overexpression of a downstream JNKK. The expression of a JNK inhibitor and induction of JNK loss-of-function clones in immune responsive tissue revealed a general requirement for JNK signaling in the expression of antimicrobial peptides. Our data indicate that dTAK1 is not required for Relish activation, but instead is required in JNK signaling for antimicrobial peptide gene expression.
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| 4. |
- James, Timothy Y., et al.
(författare)
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Evolutionary significance of imbalanced nuclear ratios within heterokaryons of the basidiomycete fungus Heterobasidion parviporum
- 2008
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 62:9, s. 2279-2296
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Tidskriftsartikel (refereegranskat)abstract
- Many fungi have heterokaryotic life stages in which genetically different nuclei inhabit the same cell. In basidiomycetes, the heterokaryon is the product of mating and represents a genomic union very similar to a diploid thallus, yet the maintenance of unfused nuclei suggests a more complex association of the two genomes relative to diploidy. In species with variable numbers of nuclei per heterokaryotic cell, nuclear ratios within a mycelium may possibly become imbalanced (differ from 1:1) due to nuclear competition. In this study, heterokaryons of the basidiomycete Heterobasidion parviporum were examined to determine the effects of genotype and environment on nuclear ratios within vegetative mycelia. The data reveal that nuclear ratios are frequently imbalanced, generally stable over time, and genetically determined. The nuclear ratios were affected by environment, but the observed nuclear ratios did not follow the expectations of strong selection acting on a population of nuclei. Instead, these ratios were largely driven by genetic effects and epigenetic effects. Finally, the data suggest that nuclear ratio imbalance also affects both gene transcription and growth rate, implying that heterokaryotic basidiomycetes are not functionally equivalent to diploid individuals and have a higher potential for genotypic and phenotypic variation.
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| 5. |
- James, Timothy Y, et al.
(författare)
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Trikaryon formation and nuclear selection in pairings between heterokaryons and homokaryons of the root rot pathogen Heterobasidion parviporum
- 2009
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Ingår i: Mycological Research. - : Elsevier BV. - 0953-7562 .- 1469-8102. ; 113:5, s. 583-590
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Tidskriftsartikel (refereegranskat)abstract
- Pairings between heterokaryons and homokaryons of Agaricomycete fungi (he-ho pairings) can lead to either heterokaryotization of the homokaryon or displacement of the homokaryotic nucleus through migration of nuclei from the heterokaryon into the homokaryon. in species of Agaricomycetes with multinucleate cells (> 2 nuclei per cell), he-ho pairings could result in the stable or transient formation of a hypha with three genetically different nuclei (trikaryons). in this study, he-ho pairings were conducted using the multinucleate Agaricomycete Heterobasidion parviporum to determine whether trikaryons can be formed in the laboratory and whether nuclear genotype affects migration and heterokaryon formation. Nuclei were tracked by genotyping the heterokaryotic mycelium using nucleus-specific microsatellite markers. The data indicated that certain nuclear combinations were favored, and that nuclei from some strains had a higher rate of migration. A high percentage of trikaryons (19 %) displaying three microsatellite alleles per locus were identified among subcultures of the he-ho pairings. Using hyphal tip and conidial isolation, we verified that nuclei of three different mating types can inhabit the same mycelium, and one of the trikaryotic strains was judged to be semi-stable over multiple sub-culturing steps, with some hyphal tips that retained three alleles and others that reduced to two alleles per locus. These results demonstrate that nuclear competition and selection are possible outcomes of heterokaryon-homokaryon interactions in H. parviporum and confirm that ratios of component nuclei in heterokaryons are not strictly 1:1. The high rate of trikaryon formation in this study suggests that fungi with multinucleate cells may have the potential for greater genetic diversity and recombination relative to dikaryotic fungi.
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