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Certain plant growth-promoting rhizobacteria (PGPR), in the absence of physical contact with a plant stimulate growth via volatile organic compound (VOC) emissions, through largely unknown mechanisms. To probe how PGPR VOCs trigger growth in plants, RNA transcript levels of Arabidopsis seedlings exposed to Bacillus subtilus (strain GB03) were examined using(More)
Cellulose is a major component of the extracellular matrices formed during development of the social amoeba, Dictyostelium discoideum. We isolated insertional mutants that failed to accumulate cellulose and had no cellulose synthase activity at any stage of development. Development proceeded normally in the null mutants up to the beginning of stalk(More)
Mechanical forces between cells have a principal role in the organization of animal tissues. Adherens junctions are an important component of these tissues, connecting cells through their actin cytoskeleton and allowing the assembly of tensile structures. At least one adherens junction protein, beta-catenin, also acts as a signalling molecule, directly(More)
Cotton (Gossypium hirsutum) provides the world's dominant renewable textile fiber, and cotton fiber is valued as a research model because of its extensive elongation and secondary wall thickening. Previously, it was assumed that fibers elongated as individual cells. In contrast, observation by cryo-field emission-scanning electron microscopy of cotton(More)
Prestalk cells of Dictyostelium discoideum contribute cellulose to two distinct structures, the stalk tube and the stalk cell wall, during culmination. This paper demonstrates by freeze fracture electron microscopy that two distinct types of intramembrane particle aggregates, which can be characterized as cellulose microfibril terminal complexes, occur in(More)
We have found a predator-prey association between the social amoeba Dictyostelium discoideum and the free soil living nematode Caenorhabditis elegans. C. elegans feeds on the amoebae and multiplies indefinitely when amoebae are the sole food source. In an environment created from soil, D. discoideum grows and develops, but not in the presence of C. elegans.(More)
The synthesis of crystalline cellulose microfibrils in plants is a highly coordinated process that occurs at the interface of the cortex, plasma membrane, and cell wall. There is evidence that cellulose biogenesis is facilitated by the interaction of several proteins, but the details are just beginning to be understood. In particular, sucrose synthase,(More)
Methods for cryogenic fixation, freeze substitution, and embedding were developed to preserve the cellular structure and protein localization of secondary-wall-stage cotton (Gossypium hirsutum L.) fibers accurately for the first time. Perturbation by specimen handling was minimized by freezing fibers still attached to a seed fragment within 2 min after(More)
Aardvark (Aar) is a Dictyostelium beta-catenin homologue with both cytoskeletal and signal transduction roles during development. Here, we show that loss of aar causes a novel phenotype where multiple stalks appear during late development. Ectopic stalks are preceded by misexpression of the stalk marker ST-lacZ in the surrounding tissue. This process does(More)
PURPOSE Although silicone hydrogel materials have produced many corneal health benefits to patients wearing contact lenses, bacteria that cause acute red eye or corneal ulcers are still a concern. A coating that inhibits bacterial colonization while not adversely affecting the cornea should improve the safety of contact lens wear. A covalent selenium (Se)(More)