Certain phenolic compounds represent a distinct class of Photosystem (PS) II Q(B) site inhibitors. In this paper, we report a detailed study of the effects of 2,4,6-trinitrophenol (TNP) and other phenolic inhibitors, bromoxynil and dinoseb, on PS II energetics. In intact PS II, phenolic inhibitors bound to only 90-95% of Q(B) sites even at saturating concentrations. The remaining PS II reaction...

It has been estimated that 375,000 tons of pesticides are used for agriculture annually in the Midwest area of the United States, where approximately 65% of this total is used for production of corn and soybean crops (Clark et al., 1999). Within the Mississippi River Basin, greater than 100,000 tons of herbicides are used annually (Clark et al., 1999). Triazine herbicides (e.g. atrazine) and sy...

A biosensor for the detection of triazine- and phenylurea-type herbicides was constructed using isolated Photosystem II (PS II) complexes as a biosensing element. PSII isolated from the thermophilic cyanobacterium Synechococcus elongatus was immobilized on the surface of a screen-printed sensor composed of a graphite working electrode and Ag/AgCl reference electrode deposited on a polymeric sub...

It is said that there are more than 5800 kinds of weeds, which significantly do harm to the agricultural production and weed control has always been an important issue in agrochemical practice. Chemical agents, that is herbicides, are used widely in the world in protecting crops from undue competition from weeds. The main chemical classes of herbicides(Tadeo et al., 2000) include bipiridilium c...

The effect of the external pH in the range of 5.5 to 8.0 on the activity of three PSII herbicides (diuron, atrazine and dinoseb) was studied in isolated thylakoid membranes by means of prompt and delayed fluorescence induction kinetics. Well-expressed pH dependence was established for prompt fluorescence parameters (Fv/Fm, Fi/Fm) as well as for delayed fluorescence parameters (I1, I2). Two type...

Weekly composite air samples were collected from early April through to mid-September 1995 at three paired urban and agricultural sites along the Mississippi River region of the Midwestern United States. The paired sampling sites were located in Mississippi, Iowa, and Minnesota. A background site, removed from dense urban and agricultural areas, was located on the shore of Lake Superior in Mich...

The number of pesticides used in agriculture is increasing steadily, leading to contamination of soil and drinking water. Herein, we present a microfluidic platform to detect the extent of contamination in soil samples. A microchip capillary electrophoresis system with in-channel electrodes was fabricated for label-free electroanalytical detection of triazine herbicides. The sample mixture cont...