| 1. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 2. |
- Davies, Melvyn B, et al.
(författare)
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Is our Sun a singleton?
- 2008
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Ingår i: Physica Scripta. - 0031-8949. ; T130
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Tidskriftsartikel (refereegranskat)abstract
- All stars are formed in some form of cluster or association. These environments can have a much higher number density of stars than the field of the galaxy. Such crowded places are hostile environments: a large fraction of initially single stars will undergo close encounters with other stars or exchange into binaries. We describe how such close encounters and exchange encounters will affect the properties of a planetary system around a single star. We define singletons as single stars which have never suffered close encounters with other stars or spent time within a binary system. It may be that planetary systems similar to our own solar system can only survive around singletons. Close encounters or the presence of a stellar companion will perturb the planetary system, leading to strong planet-planet interactions, often leaving planets on tighter and more eccentric orbits. Thus, planetary systems which initially resembled our own solar system may later more closely resemble the observed exoplanetary systems.
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| 3. |
- Davies, Melvyn B, et al.
(författare)
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The MODEST questions: Challenges and future directions in stellar cluster research
- 2006
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Ingår i: New Astronomy. - : Elsevier BV. - 1384-1092 .- 1384-1076. ; 12:3, s. 201-214
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Forskningsöversikt (refereegranskat)abstract
- We present a review of some of the current major challenges in stellar cluster research, including young clusters, globular clusters, and galactic nuclei. Topics considered include: primordial mass segregation and runaway mergers, expulsion of gas from clusters, the production of stellar exotica seen in some clusters (e.g., blue stragglers and extreme horizontal-branch stars), binary populations within clusters, the black-hole population within stellar clusters, the final parsec problem, stellar dynamics around a massive black hole, and stellar collisions. The Modest Questions posed here are the outcome of discussions which took place at the Modest-6A workshop held in Lund, Sweden, in December, 2005. Modest-6A was organised as part of the activities of the Modest Collaboration (see www.manybody.org for further details).
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| 4. |
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| 5. |
- Mackey, A D, et al.
(författare)
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Black holes and core expansion in massive star clusters
- 2008
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 0035-8711. ; 386:1, s. 65-95
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Forskningsöversikt (refereegranskat)abstract
- In this study we present the results from realistic N-body modelling of massive star clusters in the Magellanic Clouds. We have computed eight simulations with N similar to 10(5) particles; six of these were evolved for at least a Hubble time. The aim of this modelling is to examine in detail the possibility of large-scale core expansion in massive star clusters, and search for a viable dynamical origin for the radius-age trend observed for such objects in the Magellanic Clouds. We identify two physical processes which can lead to significant and prolonged cluster core expansion - mass-loss due to rapid stellar evolution in a primordially mass-segregated cluster, and heating due to a retained population of stellar mass black holes, formed in the supernova explosions of the most massive cluster stars. These two processes operate over different time-scales and during different periods of a cluster's life. The former occurs only at early times and cannot drive core expansion for longer than a few hundred Myr, while the latter typically does not begin until several hundred Myr have passed, but can result in core expansion lasting for many Gyr. We investigate the behaviour of each of these expansion mechanisms under different circumstances - in clusters with varying degrees of primordial mass segregation, and in clusters with varying black hole retention fractions. In combination, the two processes can lead to a wide variety of evolutionary paths on the radius-age plane, which fully cover the observed cluster distribution and hence define a dynamical origin for the radius-age trend in the Magellanic Clouds. We discuss in some detail the implications of core expansion for various aspects of globular cluster research, as well as the possibility of observationally inferring the presence of a significant population of stellar mass black holes in a cluster.
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| 6. |
- Mackey, A.D., et al.
(författare)
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The effect of stellar-mass black holes on the structural evolution of massive star clusters
- 2007
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 1745-3925 .- 1745-3933. ; 379, s. 40-44
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of realistic N-body modelling of massive star clusters in the Magellanic Clouds, aimed at investigating a dynamical origin for the radius-age trend observed in these systems. We find that stellar-mass black holes, formed in the supernova explosions of the most massive cluster stars, can constitute a dynamically important population. If a significant ensemble is retained (here we assume complete retention), these objects rapidly form a dense core where interactions are common, resulting in the scattering of black holes into the cluster halo, and the ejection of black holes from the cluster. These two processes heat the stellar component, resulting in prolonged core expansion of a magnitude matching the observations. Significant core evolution is also observed in Magellanic Cloud clusters at early times. We find that this does not result from the action of black holes, but can be reproduced by the effects of mass-loss due to rapid stellar evolution in a primordially mass-segregated cluster.
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| 7. |
- Mackey, Abigail L., et al.
(författare)
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The influence of anti-inflammatory medication on exercise-induced myogenic precursor cell responses in humans
- 2007
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 103:2, s. 425-431
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Tidskriftsartikel (refereegranskat)abstract
- The consumption of nonsteroidal anti-inflammatory drugs (NSAIDs) is widespread among athletes when faced with muscle soreness or injury, but the effects of NSAIDs on satellite cell activity in humans are unknown. To investigate this, 14 healthy male endurance athletes (mean peak oxygen consumption 62 ml x kg(-1) x min(-1)) volunteered for the study, which involved running 36 km. They were divided into two groups and received either 100 mg indomethacin per day or placebo. Muscle biopsies collected before the run and on days 1, 3, and 8 afterward were analyzed for satellite cells by immunohistochemistry with the aid of neural cell adhesion molecule (NCAM) and fetal antigen-1 (FA1) antibodies. Muscle biopsies were also collected from untrained individuals for comparison. Compared with preexercise levels, a 27% increase in the number of NCAM+ cells was observed on day 8 postexercise in the placebo group (P < 0.05), while levels remained similar at all time points in the NSAID group. No change was seen in the proportion of FA1+ cells, although lower levels were found in the muscle of endurance-trained athletes compared with untrained individuals (P < 0.05). These results suggest that ingestion of anti-inflammatory drugs attenuates the exercise-induced increase in satellite cell number, supporting the role of the cyclooxygenase pathway in satellite cell activity.
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| 8. |
- Malmberg, Daniel, et al.
(författare)
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Is our Sun a Singleton?
- 2008
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Ingår i: Proceedings of the International Astronomical Union. ; 246, s. 273-274
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Konferensbidrag (refereegranskat)
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| 9. |
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| 10. |
- Richards, Stephen, et al.
(författare)
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The genome of the model beetle and pest Tribolium castaneum.
- 2008
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Ingår i: Nature. - 1476-4687. ; 452:7190, s. 949-55
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Tidskriftsartikel (refereegranskat)abstract
- Tribolium castaneum is a representative of earth’s most numerous eukaryotic order, a powerful model organism for the study of generalized insect development, and also an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved an ability to interact with a diverse chemical environment as evidenced by large expansions in odorant and gustatory receptors, as well as p450 and other detoxification enzymes. Developmental patterns in Tribolium are more representative of other arthropods than those found in Drosophila, a fact represented in gene content and function. For one, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, and some are expressed in the growth zone crucial for axial elongation in short germ development. Systemic RNAi in T. castaneum appears to use mechanisms distinct from those found in C. elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.
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