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FtsZ was identified in bacteria as the first protein to localize mid-cell prior to division and homologs have been found in many plant species. Bacterial studies demonstrated that FtsZ forms a ring structure that is dynamically exchanged with a soluble pool of FtsZ. Our previous work established that Arabidopsis FtsZ1 and FtsZ2-1 are capable of in vitro self-assembly into two distinct filament types, termed type-I and type-II and noted the presence of filament precursor molecules which prompted this investigation. Using a combination of electron microscopy, gel chromatography and native PAGE revealed that (i) prior to FtsZ assembly initiation the pool consists solely of dimers and (ii) during assembly of the Arabidopsis FtsZ type-II filaments the most common intermediate between the dimer and filament state is a tetramer. Three-dimensional reconstructions of the observed dimer and tetramer suggest these oligomeric forms may represent consecutive steps in type-II filament assembly and a mechanism is proposed, which is expanded to include FtsZ assembly into type-I filaments. Finally, the results permit a discussion of the oligomeric nature of the soluble pool in plants., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Protein detection is a common yet time-intensive task in many laboratories. Here we report a protocol that makes use of cold microwave technology to reduce the total processing time to less than 1 h with dot and Western blot applications while yielding lower background noise at similar signal strength when compared with conventional protocols. With dot blots, the time savings was accompanied by a decrease in reagent use. With Western blots, the visibility of prestained markers was maintained, in stark contrast to conventional procedures. Experiments kept at a constant temperature of 21 degrees C support the existence of a microwave radiation effect, whereas an additional thermal effect is noted when the temperature is increased to 37 degrees C from ambient. Microwave-assisted dot blotting is suggested as an effective way of facilitating large-scale screening of expressed proteins.

Immunofluorescence labeling, using a monoclonal antibody developed against actin, revealed the relative abundance and rearrangements of F-actin arrays which occur in cells of the maize root apex as they make the developmental transition from proliferative growth in the meristem to a non-proliferative state in more mature root parts, and during the concomitant process of tissue differentiation. Cells in both the root cap and the quiescent center are depleted of F-actin, whereas it is abundant in cells of the central cylinder but less so in the cortex. The cortical cytoplasm associated with the endwalls of both mitotic and postomitotic cells is characterized by a more intense reactivity to the actin antibody than the longitudinal side walls. A major change in F-actin arrangement occurs in the transitional growth region interpolated between the meristem and the zone of rapid cell elongation. The location and nature of these F-actin rearrangements within the root suggest that the F-actin system might be involved in generating a force associated with the developmental transition of cells from their slow near-isotropic mode of growth close to the base of the meristem, to rapid anisotropic growth which is characteristic of the zone of cell elongation. This attraction notion was strongly supported using specific inhibitors of F-actin and myosin.