CLAVATA3, a multimeric ligand for the CLAVATA1 receptor-kinase

The CLAVATA1 (CLV1) and CLAVATA3 (CLV3) proteins form a potential receptor and ligand pair that regulates the balance between cell proliferation and differentiation at the shoot meristem of Arabidopsis. CLV1 encodes a receptor-kinase, and CLV3 encodes a predicted small, secreted polypeptide. We demonstrate that the CLV3 and CLV1 proteins coimmunoprecipitate in vivo, that yeast cells expressing CLV1 and CLV2 bind to CLV3 from plant extracts, and that binding requires CLV1 kinase activity. CLV3 only associates with the presumed active CLV1 protein complex in vivo. More than 75% of CLV3 in cauliflower extracts is bound with CLV1, consistent with hypotheses of ligand sequestration. Soluble CLV3 was found in an approximately 25-kilodalton multimeric complex.     

Stress-induced Vortex Line Helixing Avalanches in the Plastic Flow of a Smectic A Liquid Crystal

Dynamic surface force measurements of the response of a smectic A to layer normal stress exhibited time dependence for topological events in which single smectic layers were added or removed. Single layer-sized jumps in sample thickness had a rapid component of duration of approximately 1 second that produced most of the change in separation, but that was heralded by a slow precursor acceleration in separation, which began up to a few hundred seconds before. This avalanche-like dynamic signature is consistent with a relaxation mechanism based on the Glaberson-Clem-Bourdon instability of vortex lines (screw dislocations) in the smectic order parameter.     

Correlation of phytotoxin production with pathogenicity ofStreptomyces scabies isolates from scab infected potato tubers

A total of 23 isolates obtained from scab infected potato tubers representative of six sampling areas in Eastern and Central Canada and five ATCCStreptomyces strains were screened for pathogenicity on the basis of their ability to initiate scab development on aseptically cultured minitubers and plant generated tubers. The results were then correlated with any associated generation of the scab inducing phytotoxin, Thaxtomin A. In all cases a positive correlation was demonstrated between the pathogenicity of variousStreptomyces scabies isolates and their ability to produce the phytotoxin.     

Early uptake of 15N in shortgrass prairie

The early uptake ¹⁵N fertilizer in grassland was monitored by means of destructive samplings during the first two weeks after application. The predominantly litter compartments (aboveground dead, senescent and detrital roots) accounted for two-thirds of the ¹⁵N immobilization in plant parts in the first few hours after fertilization. This uptake is believed due partly to adsorption and partly to immobilization by the microorganisms associated with senescent and detrital plant parts. By 14 days, green tops and crowns accounted for 72%; live roots, 7%; and the aboveground dead and senescent and detrital roots, 21% of the total ¹⁵N uptake by the plant materials. The distribution of applied ¹⁵N between live and litter compartments was not significantly affected by rate of application.     

Effectiveness of innovative organic amendments in acid soils depends on their ability to supply P and alleviate Al and Mn toxicity in plants

Journal of Soils and Sediments - Soil acidity with high Al3+ and Mn2+ is one of the major constraints to global food production. Lime is effective to increase soil pH, but it is not always readily...