Arabidopsis PIC30 encodes a major facilitator superfamily transporter responsible for the uptake of picolinate herbicides.

Picloram is an auxinic herbicide that is widely used for controlling broad leaf weeds. However, its mechanism of transport into plants is poorly understood. In a genetic screen for picloram resistance, we identified three Arabidopsis mutant alleles of PIC30 (PICLORAM RESISTANT30) that are specifically resistant to picolinates, but not to other auxins. PIC30 is a previously uncharacterized gene that encodes a major facilitator superfamily (MFS) transporter. Similar to most members of MFS, PIC30 contains 12 putative transmembrane domains, and PIC30-GFP fusion protein selectively localizes to the plasma membrane. In planta transport assays demonstrate that PIC30 specifically transports picloram, but not indole-3-acetic acid (IAA). Functional analysis of Xenopus laevis oocytes injected with PIC30 cRNA demonstrated PIC30 mediated transport of picloram and several anions, including nitrate and chloride. Consistent with these roles of PIC30, three allelic pic30 mutants are selectively insensitive to picolinate herbicides, while pic30-3 is also defective in chlorate (analogue of nitrate) transport and also shows reduced uptake of 15NO3- . Overexpression of PIC30 fully complements both picloram and chlorate insensitive phenotypes of pic30-3. Despite the continued use of picloram as an herbicide, a transporter for picloram was not known until now. This work provides insight into the mechanisms of plant resistance to picolinate herbicides and also shed light on the possible endogenous function of PIC30 protein.

Real-time simulation of accidental passive transport of radioactive pollutant from a proposed nuclear power plant.

Power plant's site selection is a complex task and involves through analyses of multi-disciplinary processes which are interlinked with each other. The site selection for nuclear power plants additionally requires an assessment of radiation doses to the environment and public during normal operation and in the case of an accident. This demands the problem of radioactive particles' dispersion in atmosphere to be analysed in real time for a comprehensive set of radioactive release scenarios in prevailing meteorological conditions in the plant surroundings. In this study, a local scale atmospheric dispersion problem, considering a hypothetical accidental release (1 Bq s-1of I-131) from a nuclear power plant is simulated with a combination of weather forecasting and particle dispersion codes on a multiprocessor computer system. The meteorological parameters are predicted with a weather research and forecasting (WRF) model and used in Lagrangian particle dispersion model based code FLEXPART to calculate the trajectory of released particles, and thereby, the estimation of spatial I-131 dose distribution. The concentration of particles and radiation doses were calculated for release heights of 10, 57, and 107 m and found in a reasonable agreement with the observed data and better than an earlier investigation done with regional atmospheric modelling system (RAMS) code. A comparison between the results of WRF and RAMS for various meteorological parameters revealed that better space-time predictions of wind speeds and directions by WRF had a profound effect on tracing the trajectories of particles and thereby the spatial dose distribution. The particles followed the changes in wind direction predicted by WRF that were known to prevail in the region.

S-protected thiolated hydroxyethyl cellulose (HEC): Novel mucoadhesive excipient with improved stability.

The aim of this study was the design of novel S-protected thiolated hydroxyethyl cellulose (HEC) and the assessment of its mucoadhesive properties and biodegradability compared to the corresponding unmodified polymer. Thiolated HEC was S-protected via disulfide bond formation between 6-mercaptonicotinamide (6-MNA) and the thiol substructures of the polymer. In vitro screening of mucoadhesive properties was accomplished using two different methods: rotating cylinder studies and viscosity measurements. Moreover, biodegradability of these polymers by cellulase, xylanase and lysozyme was evaluated. MTT and LDH assays were performed on Caco-2 cells to determine the cytotoxicity of S-protected thiolated HEC. Thiolated HEC displayed 280.09±1.70µmol of free thiol groups per gram polymer. S-protected thiolated HEC exhibiting 270.8±21.11µmol immobilized 6-MNA ligands per gram of polymer was shown being 2.4-fold more mucoadhesive compared to thiolated HEC. No mucoadhesion was observed in case of unmodified HEC. Results were in a good agreement with rheological studies. The presence of free thiol moieties likely caused lower degree of hydrolysis by xylanase, whereas the degradation by both enzymes cellulase and xylanase was more hampered when 6-MNA was introduced as ligand for thiol group's protection. Findings in cell viability revealed that all three conjugates were non-toxic. S-protection of thiolated hydroxyethyl cellulose improved mucoadhesive properties and provided pronounced stability towards enzymatic attack, that makes this excipient superior for non-invasive drug administration over thiolated and unmodified forms.