LXX. A potentiometer for thermocouple measurements

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A Systems Biology Approach Identifies a R2R3 MYB Gene Subfamily with Distinct and Overlapping Functions in Regulation of Aliphatic Glucosinolates

BACKGROUND: Glucosinolates are natural metabolites in the order Brassicales that defend plants against both herbivores and pathogens and can attract specialized insects. Knowledge about the genes controlling glucosinolate regulation is limited. Here, we identify three R2R3 MYB transcription factors regulating aliphatic glucosinolate biosynthesis in Arabidopsis by combining several systems biology tools. METHODOLOGY/PRINCIPAL FINDINGS: MYB28 was identified as a candidate regulator of aliphatic glucosinolates based on its co-localization within a genomic region controlling variation both in aliphatic glucosinolate content (metabolite QTL) and in transcript level for genes involved in the biosynthesis of aliphatic glucosinolates (expression QTL), as well as its co-expression with genes in aliphatic glucosinolate biosynthesis. A phylogenetic analysis with the R2R3 motif of MYB28 showed that it and two homologues, MYB29 and MYB76, were members of an Arabidopsis-specific clade that included three characterized regulators of indole glucosinolates. Over-expression of the individual MYB genes showed that they all had the capacity to increase the production of aliphatic glucosinolates in leaves and seeds and induce gene expression of aliphatic biosynthetic genes within leaves. Analysis of leaves and seeds of single knockout mutants showed that mutants of MYB29 and MYB76 have reductions in only short-chained aliphatic glucosinolates whereas a mutant in MYB28 has reductions in both short- and long-chained aliphatic glucosinolates. Furthermore, analysis of a double knockout in MYB28 and MYB29 identified an emergent property of the system since the absence of aliphatic glucosinolates in these plants could not be predicted by the chemotype of the single knockouts. CONCLUSIONS/SIGNIFICANCE: It seems that these cruciferous-specific MYB regulatory genes have evolved both overlapping and specific regulatory capacities. This provides a unique system within which to study the evolution of MYB regulatory factors and their downstream targets

Ein algebraisches Turbulenzmodell fuer Aestuare

Available from TIB Hannover: RO2460(30)+a-b / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Ein Algebrisches Turbulenzmodel für Ästuare

The density distribution within a fluid is of great importance for flow and transport phenomena in geophysical computational fluid dynamics. All turbulent exchange processes are influenced by buoyancy effects and must be adequately considered in numerical models. Parameterizations of the vertical eddy viscosity and eddy diffusivity are presented for application in estuarine simulations. This model is implemented in a 2D vertically structured finite difference scheme. The algebraic turbulence model is based on the mixing length assumption and damping functions. Schematic test cases and a long term simulation of three months for a salt wedge estuary show that this is an adequate parameterization of the turbulent exchange processes. Without any change of coefficients the model is applied to a well mixed estuary giving equally satisfactory results. A comparison of commonly used mixing length approaches for homogeneous and stratified flows shows differences near the surface which modify the flow field considerably and consequently effect the advective transport of scalar quantities. Simulations of laboratory experiments corroborate a mixing length formulation for the eddy viscosity which can be derived from free surface flow conditions assuming the logarithmic velocity profile and a linear shear stress distribution. The applied damping functions depend on the gradient Richardson number and comply with limiting conditions which are derived from energy redistribution considerations. The coefficients of these functions are determined from data of the atmospheric layer which is an environment quite different from the intended area of application, so as to avoid any system specific calibration. A comparison of model runs in a case-study of the Trave estuary demonstrates that constant eddy coefficients lead to systematic errors even within short simulation periods. With the algebraic turbulence model presented in this study simulations of estuaries which are primarily characterized by an equilibrium of horizontal advection and vertical diffusion reproduce even complex transport processes with sufficient accuracy

On Financiers' Profits

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