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- Zhang, X P, et al.
(författare)
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Mutagenesis and computer modelling approach to study determinants for recognition of signal peptides by the mitochondrial processing peptidase
- 2001
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Ingår i: The Plant Journal. - 0960-7412 .- 1365-313X. ; 27:5, s. 427-438
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Tidskriftsartikel (refereegranskat)abstract
- Determinants for the recognition of a mitochondrial presequence by the mitochondrial processing peptidase (MPP) have been investigated using mutagenesis and bioinformatics approaches. All plant mitochondrial presequences with a cleavage site that was confirmed by experimental studies can be grouped into three classes. Two major classes contain an arginine residue at position -2 or -3, and the third class does not have any conserved arginines. Sequence logos revealed loosely conserved cleavage motifs for the first two classes but no significant amino acid conservation for the third class. Investigation of processing determinants for a class III precursor, Nicotiana plumbaginifolia F(1)beta precursor of ATP synthase (pF(1)beta), was performed using a series of pF(1)beta presequence mutants and mutant presequence peptides derived from the C-terminal portion of the presequence. Replacement of -2 Gln by Arg inhibited processing, whereas replacement of either the most proximally located -5 Arg or -15 Arg by Leu had only a low inhibitory effect. The C-terminal portion of the pF(1)beta presequence forms a helix-turn-helix structure. Mutations disturbing or prolonging the helical element upstream of the cleavage site inhibited processing significantly. Structural models of potato MPP and the C-terminal pF(1)beta presequence peptide were built by homology modelling and empirical conformational energy search methods, respectively. Molecular docking of the pF(1)beta presequence peptide to the MPP model suggested binding of the peptide to the negatively charged binding cleft formed by the alpha -MPP and beta -MPP subunits in close proximity to the H111XXE114H115X(116-190)E191 proteolytic active site on beta -MPP. Our results show for the first time that the amino acid at the -2 position, even if not an arginine, as well as structural properties of the C-terminal portion of the presequence are important determinants for the processing of a class III precursor by MPP.
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- 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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- Eriksson, Malin, et al.
(författare)
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I stand on my own two feet but need someone who really cares : Social networks and social capital among unaccompanied minors for becoming established in Swedish society
- 2019
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Ingår i: The Journal of Refugee Studies. - : Oxford University Press. - 0951-6328 .- 1471-6925. ; 32:3, s. 372-396
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Tidskriftsartikel (refereegranskat)abstract
- Settling in a new host country as an unaccompanied minor holds a lot of challenges such as adaptation of new social norms, learning a new language and understanding a new culture. Social networks may foster good conditions for settlement in the host community but little is known about the availability, quality and significance of social networks for unaccompanied minors (UM) in Sweden. The aim of this qualitative grounded-theory situational study was to explore experiences of social networks among UM and the significance of those networks for becoming established in Sweden, based on data from in-depth interviews with 11 young persons. Unaccompanied young persons were broadly found to be involved in three different kinds of networks: professional carers, like-ethnic friends and ‘Swedes’ in general. Networks with professionals (i.e. linking social capital) were perceived as both a secure base and a source of rejection, and could either facilitate or obstruct the establishment. Supporting networks with like-ethnic friends (bonding social capital) proved to be the most available and important resource for becoming established, while access to networks with Swedes (bridging social capital) was in general low but still perceived as important for becoming established, not least for reducing language and cultural barriers.
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