Residues and Dissipation of the Herbicide Imazapyr after Operational Use in Irrigation Water.

Imazapyr is a herbicide that can be used in irrigation canals to control a range of aquatic weed species, however, its residual nature, combined with its phytotoxicity to crops at low concentrations, means that the water in canals must be carefully managed following imazapyr application. Residues of the herbicide imazapyr (isopropylamine salt) in irrigation water were analysed and modelled after application to irrigation canals in south-eastern Australia. A treatment program to control delta arrowhead (sagittaria; (Engelm.

Sediment Facilitates Microbial Degradation of the Herbicides Endothall Monoamine Salt and Endothall Dipotassium Salt in an Aquatic Environment.

Endothall dipotassium salt and monoamine salt are herbicide formulations used for controlling submerged aquatic macrophytes and algae in aquatic ecosystems. Microbial activity is the primary degradation pathway for endothall. To better understand what influences endothall degradation, we conducted a mesocosm experiment to (1) evaluate the effects of different water and sediment sources on degradation, and (2) determine if degradation was faster in the presence of a microbial community previously exposed to endothall.

Characterization of the extracellular matrix of Phaeodactylum tricornutum (Bacillariophyceae): structure, composition, and adhesive characteristics.

The extracellular matrix of the ovoid and fusiform morphotypes of Phaeodactylum tricornutum (Bohlin) was characterized in detail. The structural and nanophysical properties were analyzed by microscopy. Of the two morphotypes, only the ovoid form secretes adhesive mucilage; light microscopy and scanning electron microscopy images showed that the mucilage was secreted from the girdle band region of the cell as cell-substratum tethers, accumulating on the surface forming a biofilm.

Divalent cations stabilize the aggregation of sulfated in the adhesive nanofibers of the biofouling diatom Toxarium undulatum.

A species of marine diatom, Toxarium undulatum, has emerged as a problematic biofouler of contemporary environmentally benign marine coatings. Previous analyses by atomic force microscopy (AFM) showed the cell-substratum adhesive of this alga contained macromolecules with a modular protein backbone assembled into nanofibers in which the domains of the macromolecules folded and unfolded in a co-ordinated manner. In the present study, we investigated further the composition and properties of the adhesive.

Adhesive modular proteins occur in the extracellular mucilage of the motile, pennate diatom Phaeodactylum tricornutum.

This Letter reports on adhesive modular proteins recorded by atomic force microscopy on live cells from the extracellular mucilage secreted from, and deposited around, the motile form of the pennate diatom Phaeodactylum tricornutum. This is the first report of modular proteins and their supramolecular assemblies, called adhesive nanofibers (ANFs), to be found on diatoms that use adhesives not only for substratum adhesion, but as a conduit for cell motility. The permanent adhesive pads secreted by Toxarium undulatum, a sessile centric diatom, were previously shown to possess ANFs with a modular protein backbone.