Comparative genome structure, secondary metabolite, and effector coding capacity across Cochliobolus pathogens.

The genomes of five Cochliobolus heterostrophus strains, two Cochliobolus sativus strains, three additional Cochliobolus species (Cochliobolus victoriae, Cochliobolus carbonum, Cochliobolus miyabeanus), and closely related Setosphaeria turcica were sequenced at the Joint Genome Institute (JGI). The datasets were used to identify SNPs between strains and species, unique genomic regions, core secondary metabolism genes, and small secreted protein (SSP) candidate effector encoding genes with a view towards pinpointing structural elements and gene content associated with specificity of these closely related fungi to different cereal hosts. Whole-genome alignment shows that three to five percent of each genome differs between strains of the same species, while a quarter of each genome differs between species. On average, SNP counts among field isolates of the same C. heterostrophus species are more than 25× higher than those between inbred lines and 50× lower than SNPs between Cochliobolus species. The suites of nonribosomal peptide synthetase (NRPS), polyketide synthase (PKS), and SSP-encoding genes are astoundingly diverse among species but remarkably conserved among isolates of the same species, whether inbred or field strains, except for defining examples that map to unique genomic regions. Functional analysis of several strain-unique PKSs and NRPSs reveal a strong correlation with a role in virulence

Behaviour of current in gas discharge system between parallel-plane electrodes

WOS: 000074798600010The current-voltage characteristics of a gas discharge system in parallel-plane geometry are studied. The gas discharge system with a photosensitive semiconductor cathode have been studied in a wide range of the gas pressures p (21.3 - 1013 hPa), inter-electrode distances d (10 mu m - 5 mm), and conductivities of the semiconductor. Gallium arsenide (10(7) - 10(8) Omega cm) has been used as the semiconducting cathode. The cathode was irradiated on the back-side with light in a particular wavelength range that was used to control the photoconductivity of the material. The semiconductor material was found to "stabilize" the discharge. When the current is increased above the stable limit, breakdown or small current oscillations begin. The filamentation was primary due to the formation of a space charge of positive ions in the discharge gap which changed the discharge from the Townsend to the glow type

VISUALIZATION OF ELECTRICAL INHOMOGENEITIES IN HIGH-OHMIC SEMICONDUCTOR PLATES BY AN IONIZATION-TYPE PHOTOGRAPHIC SYSTEM

A device for rapid visualization of electrical and spatial inhomegeneities of a semi-insulating GaAs (rho greater-than-or-equal-to 10(6) OMEGA cm) is described. This visualizer is a modification of the ionization type photographic system in which a semiconducting plate is placed between transparent plane parallel electrodes in the gas discharge cell. The gas discharge gaps are formed between free surfaces of the semiconductor and electrodes. When a voltage is applied to the electrodes a discharge luminescence glows in the gap under uniform infrared illumination of the semiconductor. The uniformity of glowing over the semiconductor area is determined by electrical homogeneity and infrared absorptivity of the material. The main discharge glow patterns on both sides and after chemical etching are similar, which reflects the fact that the structural defects are continuous within the plate. The observed patterns give information about EL2 centres in the GaAs semiconductor. Technical data of the ionization-type visualizer of electrical inhomogeneities in a semiconducting plate are given

The rapid visualization of resistivity inhomogeneities in high-resistivity semiconductor films

This paper describes for the first time an application of an ionization type semiconductor photographic system using a chalcopyrite-type semiconductor (CuInSe2) copper-indium-diselenide film as a target for rapid visulization of resistivity inhomogeneities. The CuInSe2 semiconductor films with a resistivity of 10(7) Omega cm (thickness 0.25 mu m) in a planar gas discharge cell, have been studied. A measurement is realized by recording the spatial distribution of the gas discharge radiation intensity between two parallel electrodes. A gas discharge gap has been formed by a dielectric separator with thicknesses ranging from 40 to 60 mu m. A discharge has been realized in air at pressures from 760-60 Torr. The assessment of the resistivity inhomogeneities is then based on an analysis of the discharge radiation, visualized by a photograph taken through the SnO2 film

Spatial stabilization of Townsend and glow discharges with a semiconducting cathode

The physical processes determining the functions of an ionization system and especially the discharge stabilization by the distributed resistance of a semiconducting cathode in such a system are studied. The current-voltage (I-U) characteristics of the system with a semiconducting GaAs cathode are obtained experimentally as functions of the gap pressure P (16-760 Torr) and inter-electrode distance d (10 mu m to 5 mm), which are varied for the first time over very wide ranges. The experiments showed that the presence of the distributed resistance affects the passage of the discharge current so that the discharge glows uniformly throughout the cathode surface and is not divided into separate filaments. The loss of stability was primarily due to the formation of a space charge of positive ions in the discharge gap which changed the discharge from the Townsend to the glow type

The ionization type semiconductor photographic system based on high-resistivity polymeric cathode

A device for detecting inhomogeneities in high-resistivity poly(N-vinylimidazole) polymeric semiconductor film of large diameter (40-60 mm) is described. A measurement of homogeneity is realized by recording the spatial distribution of the gas discharge glow intensity between two parallel electrodes. The polymeric films with a resistivity of 10(6)-10(8) Omega cm (thickness 40-80 mu m) in a planar gas discharge cell, have been studied. A gas discharge gap has been formed by a dielectric separator with the thicknesses ranging from 15 to 25 mu m. A discharge has been realized in air at pressures from 60-760 Torr. The possibilities of the visualization have been evaluated, i.e. a local change of the resistance inhomogeneity is determined by a local change of discharge glow intensity the resolution of which is determined by method of its recording

ENHANCEMENT OF THE RESOLUTION OF A SEMICONDUCTOR PHOTOGRAPHIC SYSTEM IN A MAGNETIC-FIELD

A method is described for enhancing the resolution R of a semiconductor photographic system by subjecting it to a homogenous magnetic field. Bi has been chosen as the photographic plate, since it has a large value of the cathode sputtering coefficient which is important in the formation of image by charged particle flux. A considerable increase of the resolution is observed when the applied magnetic field is parallel to the electric field between the electrodes. Effect of the magnetic field on the I - V characteristic of the system is discussed