We provide a mechanism for the activity of pectin methylesterase (PME), the enzyme that catalyses the essential first step in bacterial invasion of plant tissues. The complexes formed in the crystal using specifically methylated pectins, together with kinetic measurements of directed mutants, provide clear insights at atomic resolution into the specificity and the processive action of the Erwin...

Pathogens and antibiotics enter the aquatic environment via sewage effluents and may pose a health risk to wild life and humans. The aim of this study was to determine the levels of faecal bacteria, and selected antibiotic residues in raw wastewater and treated sewage effluents from three different sewage treatment plants in the Western Cape, South Africa. Sewage treatment plant 1 and 2 use old...

Sliced root tissue of the horseradish plant (Armoracia rusticana), when incubated with mannose-U-(14)C, incorporated radioactivity into peroxidase isoenzymes. Over 90% of the radioactivity in the highly purified peroxidase isoenzymes was present in the neutral sugar residues of the molecule, i.e. fucose, arabinose, xylose, mannose. When the root slices were incubated simultaneously with leucine...

The global terrestrial heterotrophic respiration is estimated at about 60 Gt C yr-1 (Schlesinger, 1991). Plant litter produced during senescence processes and plant residues left on site after harvest operations are the primary substrate for heterotrophic respiration in plant-soil ecosystems. They constitute both of aboveground and belowground plant parts. Substrate quality, together with the p...

vegetation that is allowed to naturally decompose isn’t realized by many ranchers and some range mangers. Mulch plays a critical role in soil-water relationships that is often overlooked. This, coupled with current drought conditions in the southwestern United States justifies a consideration of the importance of mulch on rangelands. Several early classic studies (reviewed in this article) reve...

Large quantities of Bacillus thuringiensis (Bt) corn plant residue are left in the field after harvest, which may have implications for the soil ecosystem. Potential impacts on soil organisms will also depend on the persistence of the Bt toxin in plant residues. Therefore, it is important to know how long the toxin persists in plant residues. In two field studies in the temperate corn-growing r...

This study was undertaken to determine the concentrations of carbofuran residues in water, soil and plant samples from selected sites in the farmlands in Kenya and to demonstrate the impact of Furadan use on the local environment. Soil, water and plant samples obtained from agricultural farmlands where the technical formulation Furadan has been used extensively showed high environmental contami...

Plant-produced glycoproteins contain N-linked glycans with plant-specific residues of β(1,2)-xylose and core α(1,3)-fucose, which do not exist in mammalian-derived proteins. Although our experience with two enzymes that are used for enzyme replacement therapy does not indicate that the plant sugar residues have deleterious effects, we made a conscious decision to eliminate these moieties from p...

The oomycete Hyaloperonospora arabidopsidis (Hpa) is the causal agent of downy mildew on the model plant Arabidopsis thaliana and has been adapted as a model system to investigate pathogen virulence strategies and plant disease resistance mechanisms. Recognition of Hpa infection occurs when plant resistance proteins (R-genes) detect the presence or activity of pathogen-derived protein effectors...

RNA Editing RNA editing is a term used to describe a diverse set of phenomena in which mRNA, rRNA, and tRNA transcripts are modified in sequence after transcription. The types of RNA editing vary from uridine (U) or cytidine (C) insertions and deletions within coding regions of mitochondrial mRNAs to the substitution of specific C residues with U residues in plant mitochondrial mRNAs or the sub...