Recurrent allopolyploidizations diversify ecophysiological traits in marsh orchids (Dactylorhiza majalis s.l.).

Whole-genome duplication has shaped the evolution of angiosperms and other organisms, and is important for many crops. Structural reorganization of chromosomes and repatterning of gene expression are frequently observed in allopolyploids, with physiological and ecological consequences. Recurrent origins from different parental populations are widespread among polyploids, resulting in an array of lineages that provide excellent models to uncover mechanisms of adaptation to divergent environments in early phases of polyploid evolution. We integrate here transcriptomic and ecophysiological comparative studies to show that sibling allopolyploid marsh orchid species (Dactylorhiza, Orchidaceae) occur in different habitats (low nutrient fens vs. meadows with mesic soils) and are characterized by a complex suite of intertwined, pronounced ecophysiological differences between them. We uncover distinct features in leaf elemental chemistry, light-harvesting, photoprotection, nutrient transport and stomata activity of the two sibling allopolyploids, which appear to match their specific ecologies, in particular soil chemistry differences at their native sites. We argue that the phenotypic divergence between the sibling allopolyploids has a clear genetic basis, generating ecological barriers that maintain distinct, independent lineages, despite pervasive interspecific gene flow. This suggests that recurrent origins of polyploids bring about a long-term potential to trigger and maintain functional and ecological diversity in marsh orchids and other groups

Genetic differentiation and admixture between sibling allopolyploids in the Dactylorhiza majalis complex

Allopolyploidization often happens recurrently, but the evolutionary significance of its iterative nature is not yet fully understood. Of particular interest are the gene flow dynamics and the mechanisms that allow young sibling polyploids to remain distinct while sharing the same ploidy, heritage and overlapping distribution areas. By using eight highly variable nuclear microsatellites, newly reported here, we investigate the patterns of divergence and gene flow between 386 polyploid and 42 diploid individuals, representing the sibling allopolyploids Dactylorhiza majalis s.s. and D. traunsteineri s.l. and their parents at localities across Europe. We make use in our inference of the distinct distribution ranges of the polyploids, including areas in which they are sympatric (that is, the Alps) or allopatric (for example, Pyrenees with D. majalis only and Britain with D. traunsteineri only). Our results show a phylogeographic signal, but no clear genetic differentiation between the allopolyploids, despite the visible phenotypic divergence between them. The results indicate that gene flow between sibling Dactylorhiza allopolyploids is frequent in sympatry, with potential implications for the genetic patterns across their entire distribution range. Limited interploidal introgression is also evidenced, in particular between D. incarnata and D. traunsteineri. Altogether the allopolyploid genomes appear to be porous for introgression from related diploids and polyploids. We conclude that the observed phenotypic divergence between D. majalis and D. traunsteineri is maintained by strong divergent selection on specific genomic areas with strong penetrance, but which are short enough to remain undetected by genotyping dispersed neutral markers.UE FWF; P22260UE: Y66

Minority cytotypes in European populations of the Gymnadenia conopsea complex (Orchidaceae) greatly increase intraspecific and intrapopulation diversity

Background and Aims Patterns of ploidy variation among and within populations can provide valuable insights into the evolutionary mechanisms shaping the dynamics of plant systems showing ploidy diversity. Whereas data on majority ploidies are, by definition, often sufficiently extensive, much less is known about the incidence and evolutionary role of minority cytotypes. Methods Ploidy and proportions of endoreplicated genome were determined using DAPI (4',6-diamidino-2-phenylindole) flow cytometry in 6150 Gymnadenia plants (fragrant orchids) collected from 141 populations in 17 European countries. All widely recognized European species, and several taxa of less certain taxonomic status were sampled within Gymnadenia conopsea sensu lato. Key Results Most Gymnadenia populations were taxonomically and/or ploidy heterogeneous. Two majority (2x and 4x) and three minority (3x, 5x and 6x) cytotypes were identified. Evolution largely proceeded at the diploid level, whereas tetraploids were much more geographically and taxonomically restricted. Although minority ploidies constituted <2 % of the individuals sampled, they were found in 35 % of populations across the entire area investigated. The amount of nuclear DNA, together with the level of progressively partial endoreplication, separated all Gymnadenia species currently widely recognized in Europe. Conclusions Despite their low frequency, minority cytotypes substantially increase intraspecific and intrapopulation ploidy diversity estimates for fragrant orchids. The cytogenetic structure of Gymnadenia populations is remarkably dynamic and shaped by multiple evolutionary mechanisms, including both the ongoing production of unreduced gametes and heteroploid hybridization. Overall, it is likely that the level of ploidy heterogeneity experienced by most plant species/populations is currently underestimated; intensive sampling is necessary to obtain a holistic pictur

PDGF and PDGF receptors in glioma

The family of platelet-derived growth factors (PDGFs) plays a number of critical roles in normal embryonic development, cellular differentiation, and response to tissue damage. Not surprisingly, as it is a multi-faceted regulatory system, numerous pathological conditions are associated with aberrant activity of the PDGFs and their receptors. As we and others have shown, human gliomas, especially glioblastoma, express all PDGF ligands and both the two cell surface receptors, PDGFR-α and -β. The cellular distribution of these proteins in tumors indicates that glial tumor cells are stimulated via PDGF/PDGFR-α autocrine and paracrine loops, while tumor vessels are stimulated via the PDGFR-β. Here we summarize the initial discoveries on the role of PDGF and PDGF receptors in gliomas and provide a brief overview of what is known in this field

Evolution of polyploids in the European orchid genus Nigritella: Evidence from allozyme data

The orchid genus Nigritella constitutes a polyploid complex which is widespread in mountain regions in Europe. Diploid members of the genus have sexual reproduction, whereas polyploid members are characterised by agamospermy. We used allozyme data to estimate levels of variation at different hierarchical levels and to describe the evolution of polyploids. - The variation patterns at allozyme loci agree with the mode of reproduction. Thus, populations of diploid species are variable, whereas populations of polyploid species contain one or two multilocus genotypes. The two tetraploids N. widderi and N. miniata contained two different multilocus genotypes each, indicating either multiple origins, or else sexual recombination or mutation at the tetraploid level. - The two tetraploids N. nigra subsp. austriaca and N. nigra subsp. iberica are closely related to the triploid N. nigra subsp. nigra, and they may have evolved by hybridization of this triploid and a diploid species. - In agreement with previous data, allozyme data confirm that the tetraploid apomict Gymnigritella runei is formed by fusion of an unreduced gamete from N. nigra subsp. nigra with a normal, haploid gamete from Gymnadenia conopsea. - The multilocus genotype found in Nigritella archiducis-joannis was identical to one multilocus genotype found in N. widderi, indicating that they may have evolved from a similar set of parental taxa. The pentaploid N. buschmanniae may be derived by hybridization of N. widderi with a sexual diploid species. - The multilocus genotype found in N. widderi was identical to one of the multilocus genotypes found in N. miniata, indicating a close relationship of these taxa as well. - The polyploid species investigated appear to combine divergent genomes and are likely to be derived by allopolyploidization. They all contain alleles that are rare or absent from present-day diploids, indicating that the polyploid taxa are derived from extinct ancestors and that they may have evolved at least before the last glaciation. - A comparison with two species of Gymnadenia, G. conopsea and G. odoratissima, revealed that Gymnadenia and Nigritella are more divergent from each other than species within each genus, which agrees with the view that the genera are sister groups

MANAGING MANDATED ADOPTION: PRE-DEPLOYMENT ATTITUDES AND BELIEFS IN THE CONTEXT OF CRITICAL CARE

This research develops and tests a theoretical model on the impact of antecedents on technology adoption developing valuable insight into influencing levels of attitudes and expectations prior to deployment of a mandated to use system. Two stages during the pre-deployment phase of a mission-critical, mandated system are studied. Results are reported from a two cross-sections field study of 263 and 185 users (physicians, nurses and nurse affiliates) at Critical Care departments of two hospitals implementing a Patient Data Management System. The results indicate that prior to deployment, Trust is the most important predictor of attitudes and expectations. The proposed model explains a relatively large amount of the variance, (64% and 69%) in attitude and (57% and 47%) in expectations before and after training in system use, respectively