Role of Bacterial Communities in the Natural Suppression of Rhizoctonia solani Bare Patch Disease of Wheat (Triticum aestivum L.)

Rhizoctonia bare patch and root rot disease of wheat, caused by Rhizoctonia solani AG-8, develops as distinct patches of stunted plants and limits the yield of direct-seeded (no-till) wheat in the Pacific Northwest of the United States. At the site of a long-term cropping systems study near Ritzville, WA, a decline in Rhizoctonia patch disease was observed over an 11-year period. Bacterial communities from bulk and rhizosphere soil of plants from inside the patches, outside the patches, and recovered patches were analyzed by using pyrosequencing with primers designed for 16S rRNA. Taxa in the class Acidobacteria and the genus Gemmatimonas were found at higher frequencies in the rhizosphere of healthy plants outside the patches than in that of diseased plants from inside the patches. Dyella and Acidobacteria subgroup Gp7 were found at higher frequencies in recovered patches. Chitinophaga, Pedobacter, Oxalobacteriaceae (Duganella and Massilia), and Chyseobacterium were found at higher frequencies in the rhizosphere of diseased plants from inside the patches. For selected taxa, trends were validated by quantitative PCR (qPCR), and observed shifts of frequencies in the rhizosphere over time were duplicated in cycling experiments in the greenhouse that involved successive plantings of wheat in Rhizoctonia-inoculated soil. Chryseobacterium soldanellicola was isolated from the rhizosphere inside the patches and exhibited significant antagonism against R. solani AG-8 in vitro and in greenhouse tests. In conclusion, we identified novel bacterial taxa that respond to conditions affecting bare patch disease symptoms and that may be involved in suppression of Rhizoctonia root rot and bare batch disease.     

Polyamine derivatives as inhibitors of trypanothione reductase and assessment of their trypanocidal activities

Trypanothione reductase (TR) occurs exclusively in trypanosomes and leishmania, which are the etiological agents of many diseases. TR plays a vital role in the antioxidant defenses of these parasites and inhibitors of TR have potential as antitrypanosomal agents. We describe the syntheses of several spermine and spermidine derivatives and the inhibiting effects of these compounds on T. cruzi TR. All of the inhibiting compounds displayed competitive inhibition of TR-mediated reduction of trypanothione disulfide. The three most effective compounds studied were N⁴,N⁸-bis(3-phenylpropyl)spermine (12), N⁴,N⁸-bis(2-naphthylmethyl)spermine (14), and N¹,N⁸-bis(2-naphthylmethyl)spermidine (21), with K_i values of 3.5, 5.5 and 9.5 μM, respectively. Compounds 12, 14, and 21 were found to be potent trypanocides in vitro with IC₅₀ values ranging from 0.19 to 0.83 μM against four T. brucei ssp. strains. However, these compounds did not prolong the lives of mice infected with trypanosomes. This work indicates that certain polyamine derivatives which target a unique pathway in Trypanosomatidae have potential as antitrypanosomal agents.     

A comparison of the inhibitory effects of somatostatin-14, -25, and -28 on motility of the guinea pig ileum

A number of studies have suggested that somatostatin-14 (SS-14) and somatostatin-28 (SS-28) exhibit a similar spectrum of biological activities but have different potencies. In the present study the effects of SS-14, SS-28, and somatostatin-25 on electrically induced contractions of the guinea pig ileum have been compared. All three peptides exhibited equipotent inhibitory effects. Inhibition was obtained at a threshold concentration less than 10(-10) M, with maximal inhibition at 10(-7) M and IC50 values of 6.0-6.5 X 10(-10) M. The N-terminal 14 amino acid fragment of SS-28 had no effect either on motility, when added alone, or on the actions of SS-28, suggesting that this region of the molecule is not critical for biological activity.     

Retroviral-mediated gene transfer of the leukocyte integrin CD18 subunit

Children with leukocyte adherence deficiency (LAD) exhibit heterogeneous defects in the leukocyte integrin CD18 subunit that prevent surface expression of functional CD11/CD18 leukocyte integrin adherence complexes. We used a retroviral vector, designated LCD18SN, to transfer the CD18 cDNA into K562 human myeloid leukemia cells and into EBV B-cells from a child with LAD. Transfer of the LCD18SN retroviral construct, which expresses the CD18 cDNA from the Moloney Murine leukemia virus (MoMLV) long terminal repeat (LTR), into K562 cells resulted in relatively high levels of CD18 mRNA and intracellular protein. Retroviral-mediated gene transfer of CD18 into LAD EBV B-cells resulted in low, but readily measurable, levels of surface expression of the CD11a/CD18 complex in these previously deficient lymphocytes. The reconstitution of surface expression of the CD11a/CD18 complex by gene transfer of the CD18 cDNA into LAD EBV B-cells indicates that this syndrome represents a candidate disorder for gene therapy.     

Integrating across neuroimaging modalities boosts prediction accuracy of cognitive ability

Variation in cognitive ability arises from subtle differences in underlying neural architecture. Understanding and predicting individual variability in cognition from the differences in brain networks requires harnessing the unique variance captured by different neuroimaging modalities. Here we adopted a multi-level machine learning approach that combines diffusion, functional, and structural MRI data from the Human Connectome Project (N = 1050) to provide unitary prediction models of various cognitive abilities: global cognitive function, fluid intelligence, crystallized intelligence, impulsivity, spatial orientation, verbal episodic memory and sustained attention. Out-of-sample predictions of each cognitive score were first generated using a sparsity-constrained principal component regression on individual neuroimaging modalities. These individual predictions were then aggregated and submitted to a LASSO estimator that removed redundant variability across channels. This stacked prediction led to a significant improvement in accuracy, relative to the best single modality predictions (approximately 1% to more than 3% boost in variance explained), across a majority of the cognitive abilities tested. Further analysis found that diffusion and brain surface properties contribute the most to the predictive power. Our findings establish a lower bound to predict individual differences in cognition using multiple neuroimaging measures of brain architecture, both structural and functional, quantify the relative predictive power of the different imaging modalities, and reveal how each modality provides unique and complementary information about individual differences in cognitive function.     

Calpains mediate integrin attachment complex maintenance of adult muscle in Caenorhabditis elegans

Two components of integrin containing attachment complexes, UNC-97/PINCH and UNC-112/MIG-2/Kindlin-2, were recently identified as negative regulators of muscle protein degradation and as having decreased mRNA levels in response to spaceflight. Integrin complexes transmit force between the inside and outside of muscle cells and signal changes in muscle size in response to force and, perhaps, disuse. We therefore investigated the effects of acute decreases in expression of the genes encoding these multi-protein complexes. We find that in fully developed adult Caenorhabditis elegans muscle, RNAi against genes encoding core, and peripheral, members of these complexes induces protein degradation, myofibrillar and mitochondrial dystrophies, and a movement defect. Genetic disruption of Z-line- or M-line-specific complex members is sufficient to induce these defects. We confirmed that defects occur in temperature-sensitive mutants for two of the genes: unc-52, which encodes the extra-cellular ligand Perlecan, and unc-112, which encodes the intracellular component Kindlin-2. These results demonstrate that integrin containing attachment complexes, as a whole, are required for proper maintenance of adult muscle. These defects, and collapse of arrayed attachment complexes into ball like structures, are blocked when DIM-1 levels are reduced. Degradation is also blocked by RNAi or drugs targeting calpains, implying that disruption of integrin containing complexes results in calpain activation. In wild-type animals, either during development or in adults, RNAi against calpain genes results in integrin muscle attachment disruptions and consequent sub-cellular defects. These results demonstrate that calpains are required for proper assembly and maintenance of integrin attachment complexes. Taken together our data provide in vivo evidence that a calpain-based molecular repair mechanism exists for dealing with attachment complex disruption in adult muscle. Since C. elegans lacks satellite cells, this mechanism is intrinsic to the muscles and raises the question if such a mechanism also exists in higher metazoans.     

Recovery of Sugars from Ionic Liquid Biomass Liquor by Solvent Extraction

The dissolution of biomass into ionic liquids (ILs) has been shown to be a promising alternative biomass pretreatment technology, facilitating faster breakdown of cellulose through the disruption of lignin and the decrystallization of cellulose. Both biological and chemical catalysis have been employed to enhance the conversion of IL-treated biomass polysaccharides into monomeric sugars. However, biomass-dissolving ILs, sugar monomers, and smaller carbohydrate oligomers are all soluble in water. This reduces the overall sugar content in the recovered solid biomass and complicates the recovery and recycle of the IL. Near-complete recovery of the IL and the holocellulose is essential for an IL-based pretreatment technology to be economically feasible. To address this, a solvent extraction technique, based on the chemical affinity of boronates such as phenylboronic acid and naphthalene-2-boronic acid for sugars, was applied to the extraction of glucose, xylose, and cellobiose from aqueous mixtures of 1-ethyl-3-methylimidazolium acetate. It was shown that boronate complexes could extract up to 90% of mono- and disaccharides from aqueous IL solutions, 100% IL systems, and hydrolysates of corn stover containing IL. The use of boronate complexes shows significant potential as a way to recover sugars at several stages in ionic liquid biomass pretreatment processes, delivering a concentrated solution of fermentable sugars, minimizing toxic byproducts, and facilitating ionic liquid cleanup and recycle.