| 1. |
- Alheim, Katarina, et al.
(författare)
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Identification of a functional glucocorticoid response element in the promoter of the cylcin-dependant kinase inhibitor p57(Kip2)
- 2003
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Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 30:3, s. 359-368
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Tidskriftsartikel (refereegranskat)abstract
- Glucocorticoids are known regulators of the cell cycle, normally exerting an anti-proliferative effect. We have previously shown that glucocorticoids stimulate expression of p57(Kip2), a member of the Cip/Kip family of cyclin-dependent kinase inhibitors which, in some cell types, may account for the anti-proliferative responses seen after glucocorticoid treatment. The induction of p57(Kip2) involves primary transcriptional effects where no de novo protein synthesis is necessary, suggesting a direct interaction of the glucocorticoid receptor with the p57(Kip2) gene. In this study we have identified a functional glucocorticoid response element (GRE), located 5 kilo bases (kb) upstream of the transcription start site in the human P57(Kip2) promoter. This GRE was functional also when isolated, suggesting a direct transcriptional effect of the glucocorticoid receptor. Furthermore, mutation of this GRE abolished glucocorticoid induction of the reporter gene, whereas mutation of a nearby Sp1 site did not. Using electrophoretic mobility shift assays, we have shown that the -5 kb p57(Kip2) promoter GRE was able to compete with a well-known GRE for glucocorticoid receptor binding. Sequence comparisons with the mouse genome showed that this GRE is highly conserved, further strengthening the biological importance of this site. All these data emphasize the involvement of this GRE in the glucocorticoid-mediated induction of p57(Kip2) expression.
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| 2. |
- Carlsson, J, et al.
(författare)
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Kin-biased distribution in brown trout : an effect of redd location or kin recognition?
- 2004
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 92:2, s. 53-60
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Tidskriftsartikel (refereegranskat)abstract
- A wide range of animals have been reported to show kin-biased behaviours, such as reduced aggressiveness and increased food sharing among relatives. However, less is known about whether wild animals also associate with relatives under natural conditions, which is a prerequisite to facilitate kin-biased behaviours and hence kin selection. We tested, by means of microsatellite polymorphism, correlations between pair-wise relatedness and pair-wise metric distance in wild brown trout ( Salmo trutta L.) under natural conditions in two streams. Our data show that young-of-the-year as well as older trout found close together also had a higher genetic relatedness in one of the two streams, whereas no relationship was found in the other stream. Very few half and full siblings were found in the second stream and under these conditions it is unlikely that kin-biased behaviours will receive positive selection. We discuss the underlying mechanisms for the observed structure and we specifically address the issue of whether the grouping of related individuals could reflect dispersal from the same spawning redds, or if it reflects active association with relatives, possibly conferring kin-selected advantages.
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| 3. |
- Dinnétz, Patrik, et al.
(författare)
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Population viability analysis of Saxifraga cotyledon, a perennial plant with semelparous rosettes
- 2002
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Ingår i: Plant Ecology. - 1385-0237 .- 1573-5052. ; 159:1, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- The aim with this study was to analyse the population dynamics of Saxifraga cotyledon, a rare, long lived herb, with semelparous rosettes. In Sweden, S. cotyledon grows in fragmented habitats at high altitude and is classified as vulnerable according to the IUCN system. From a five year demographical study we estimated population growth rates and extinction risks for one small and one large subpopulation. In the small subpopulation deterministic matrix simulations showed large variation, with two transitions projecting negative and two projecting positive population growth. The large subpopulation also showed large variation, but all yearly transitions projected positive population growth. In both subpopulations survival and growth contributed more than twice as much to population growth rates than did sexual reproduction, vegetative reproduction and the seed bank all taken together. In stochastic simulations the maximum likelihood growth estimator was larger than 1 for both subpopulations. None of the two subpopulations suffer from high extinction rates and although the effect of demographic stochasticity increase extinction risk in small populations it is enough with 70 individuals for a viable population of S. cotyledon. Hence, for the studied population of S. cotyledon, rareness per se is not a good indicator of vulnerability.
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