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- Bolcato-Bellemin, AL, et al.
(författare)
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Laminin alpha 5 chain is required for intestinal smooth muscle development
- 2003
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Ingår i: Developmental Biology. - 1095-564X. ; 260:2, s. 376-390
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Tidskriftsartikel (refereegranskat)abstract
- Laminins (comprised of alpha, beta, and gamma chains) are heterotrimeric glycoproteins integral to all basement membranes. The function of the lammin alpha5 chain in the developing intestine was defined by analysing laminin alpha5(-/-) mutants and by grafting experiments. We show that lammin alpha5 plays a major role in smooth muscle organisation and differentiation, as excessive folding of intestinal loops and delay in the expression of specific markers are observed in laminin alpha5(-/-) mice. In the subepithelial basement membrane, loss of alpha5 expression was paralleled by ectopic or accelerated deposition of laminin alpha2 and alpha4 chains; this may explain why no obvious defects were observed in the villous form and enterocytic differentiation. This compensation process is attributable to mesenchyme-derived molecules as assessed by chick/mouse alpha5(-/-) grafted associations. Lack of the laminin alpha5 chain was accompanied by a decrease in epithelial alpha3beta1 integrin receptor expression adjacent to the epithelia] basement membrane and of Lutheran blood group glycoprotein in the smooth muscle cells, indicating that these receptors are likely mediating interactions with laminin alpha5-containing molecules. Taken together, the data indicate that the laminin alpha5 chain is essential for normal development of the intestinal smooth muscle and point to possible mesenchyme-derived compensation to promote normal intestinal morphogenesis when laminin alpha5 is absent. (C) 2003 Elsevier Science (USA). All rights reserved.
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- Hjortswang, H I, et al.
(författare)
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KNOTTED1-like homeobox genes of a gymnosperm, Norway spruce, expressed during somatic embryogenesis
- 2002
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Ingår i: Plant physiology and biochemistry (Paris). - 0981-9428 .- 1873-2690. ; 40:10, s. 837-843
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Tidskriftsartikel (refereegranskat)abstract
- Two Norway spruce (Picea abies (L.) Karst.) genes belonging to class I of the KNOTTED1-like homeobox (KNOX) genes, HBK2 and HBK3, were cloned with PCR-based methods. The expression of these and a previously characterised related gene, HBK1, in different organs and during somatic embryogenesis was studied with RTPCR. Transcripts of all three genes were detected in stems, roots and in cone buds, but not in needles. HBK1 and HBK3 are expressed throughout development in a normal cell line with embryogenic potential and in a cell line unable to form somatic embryos. HBK2 is expressed in the normal cell line, but not in the developmentally arrested cell line. This suggests that the HBK2 gene is involved in the somatic embryo development.
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- Högberg, Karl-Anders, et al.
(författare)
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Critical factors affecting ex vitro performance of somatic embryo plants of Picea abies
- 2001
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 16:4, s. 295-304
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The potential to use somatic embryos for large-scale propagation of elite genotypes, for integration into breeding programmes and for connecting breeding and mass propagation, is receiving much attention. However, before the methods are applied it is important that the plants regenerated via somatic embryogenesis grow as expected, i.e. as seedlings or cuttings. Growth of somatic embryo plants is under a cumulative influence of a number of treatments given during the in vitro phase and during the ex vitro establishment phase. The aim of this study was to identify treatments with a negative influence on the subsequent growth of somatic embryo plants of Norway spruce (Picea abies L. Karst.). Based on the results, the time of contact with abscisic acid during somatic embryo maturation and the length of continuous light treatment (CLT) during the first growth period strongly affect the height growth during two successive growth periods. In both cases longer treatments exerted negative effects. Based on these results a new method was set up, which includes: (1) prematuration treatment of the suspension culture in a growth regulator-free medium, by which the maturation step is synchronized and contracted; and (2) a two-phase germination treatment, first on a solidified medium and then in a liquid medium. This treatment avoids extended CLT during the first growth period. Another advantage of the two-phase germination treatment is a better root-system development. Somatic embryo plants produced according to this method can be transferred directly from in vitro conditions to the greenhouse.
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- Landstrlom, L., et al.
(författare)
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In situ monitoring of size distributions and characterization of nanoparticles during W ablation in N2 atmosphere
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 94:3, s. 2011-2017
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Tidskriftsartikel (refereegranskat)abstract
- Amporphous WN0.3 nanoparticles were generated by pulsed excimer ablation of tungsten in a N2 ambient at atmospheric pressure. Size distributions and concentrations were monitored by dynamic mechanical analysis (DMA) and condensation particle counter (CPC) with different laser parameters and sport sizes. It was found that the fast desorptive part for which a thermal process for material removal was ruled out and the 'real' ablation gave rise to different types of size distributions.
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