Connecting genes, coexpression modules, and molecular signatures to environmental stress phenotypes in plants

<p>Abstract</p> <p>Background</p> <p>One of the eminent opportunities afforded by modern genomic technologies is the potential to provide a mechanistic understanding of the processes by which genetic change translates to phenotypic variation and the resultant appearance of distinct physiological traits. Indeed much progress has been made in this area, particularly in biomedicine where functional genomic information can be used to determine the physiological state (e.g., diagnosis) and predict phenotypic outcome (e.g., patient survival). Ecology currently lacks an analogous approach where genomic information can be used to diagnose the presence of a given physiological state (e.g., stress response) and then predict likely phenotypic outcomes (e.g., stress duration and tolerance, fitness).</p> <p>Results</p> <p>Here, we demonstrate that a compendium of genomic signatures can be used to classify the plant abiotic stress phenotype in <it>Arabidopsis </it>according to the architecture of the transcriptome, and then be linked with gene coexpression network analysis to determine the underlying genes governing the phenotypic response. Using this approach, we confirm the existence of known stress responsive pathways and marker genes, report a common abiotic stress responsive transcriptome and relate phenotypic classification to stress duration.</p> <p>Conclusion</p> <p>Linking genomic signatures to gene coexpression analysis provides a unique method of relating an observed plant phenotype to changes in gene expression that underlie that phenotype. Such information is critical to current and future investigations in plant biology and, in particular, to evolutionary ecology, where a mechanistic understanding of adaptive physiological responses to abiotic stress can provide researchers with a tool of great predictive value in understanding species and population level adaptation to climate change.</p

SEPARATION OF THE COHERENT AND INCOHERENT SCATTERING OF C2Cl6 BY POLARIZATION ANALYSIS

Dans la diffusion des neutrons par C2Cl6, la contribution incohérente à la largeur quasiélastique donne des informations sur le mouvement réorientationnel des molécules à partir de la diffusion des atomes individuels. La diffusion cohérente contient par contre des effets d'interférence. L'analyse de polarisation permet de distinguer entre la diffusion cohérente et la diffusion de spin incohérente. S'il est possible de moduler la polarisation du faisceau incident, on peut effectuer une expérience en temps de vol à haute résolution, avec analyse de polarisation. Sur le diffractomètre D7, nous avons utilisé huit détecteurs avec analyseur à supermiroir de section efficace de 10 x 5 cm2 et un polariseur à supermiroir. Un flipper de Mezei fonctionnant avec une séquence de pulses pseudostatistiques et un second polariseur, génère le faisceau modulé de neutrons dans un état de spin donné. Les résultats montrent qu'il est possible de séparer les contributions cohérente et incohérente. Une analyse des résultats de temps de vol permet de déterminer les temps de relaxation des mouvements moléculaires.In neutron scattering by C2Cl6 the incoherent contribution to the quasi-elastic linewidth gives information on the reorientational motion of the molecules by scattering on individual atoms. The coherent scattering contains in contrast also interference effects. With polarisation analysis it is possible to distinguish between coherent and spin incoherent scattering. If it is possible to modulate the polarisation of the incoming beam one can perform high resolution TOF experiments simultaneously with polarisation analysis. On the diffractometer D7 we use 8 detectors with supermirror analysers of 10 x 5 cm2 cross-section and a supermirror polariser. A Mezei flipper supplied with a pseudostatistical pulse sequence and a second polariser generate the modulated neutron beam of one spin state. The results show that it is possible to separate the coherent and incoherent scattering peak. An analysis of the TOF data gives the relaxation times of the molecular motion

57 Fe NCR of Fe phases in “magnetic cassiterites”

A pyralspite garnet from an anomalously magnetic concentrate of a pegmatitic cassiterite ore has been investigated using 57 Fe nuclear gamma-ray resonance spectroscopy. The quadrupole splitting and isomer shift values of 3.6 mm/s and 1.4 mm/s, respectively, are among the largest observed for Fe 2+ ions and indicate a very low covalency of the dodecahedral Fe 2+ — O 2 -bonds. These data support the more recent and lower value (10.2–10.1 kcal/ mole) of White and Moore (1972) for the CFSE of the dodecahedral Fe 2+ ion and suggest that the CFSE should be a useful approximation to the site preference energy of Fe 2+ for this site.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47320/1/410_2004_Article_BF00372603.pd