Cellulose Biosynthesis Inhibitors: Comparative Effect on Bean Cell Cultures

The variety of bioassays developed to evaluate different inhibition responses for cellulose biosynthesis inhibitors makes it difficult to compare the results obtained. This work aims (i) to test a single inhibitory assay for comparing active concentrations of a set of putative cellulose biosynthesis inhibitors and (ii) to characterize their effect on cell wall polysaccharides biosynthesis following a short-term exposure. For the first aim, dose-response curves for inhibition of dry-weight increase following a 30 days exposure of bean callus-cultured cells to these inhibitors were obtained. The compound concentration capable of inhibiting dry weight increase by 50% compared to control (I50) ranged from subnanomolar (CGA 325′615) to nanomolar (AE F150944, flupoxam, triazofenamide and oxaziclomefone) and micromolar (dichlobenil, quinclorac and compound 1) concentrations. In order to gain a better understanding of the effect of the putative inhibitors on cell wall polysaccharides biosynthesis, the [14C]glucose incorporation into cell wall fractions was determined after a 20 h exposure of cell suspensions to each inhibitor at their I50 value. All the inhibitors tested decreased glucose incorporation into cellulose with the exception of quinclorac, which increased it. In some herbicide treatments, reduction in the incorporation into cellulose was accompanied by an increase in the incorporation into other fractions. In order to appreciate the effect of the inhibitors on cell wall partitioning, a cluster and Principal Component Analysis (PCA) based on the relative contribution of [14C]glucose incorporation into the different cell wall fractions were performed, and three groups of compounds were identified. The first group included quinclorac, which increased glucose incorporation into cellulose; the second group consisted of compound 1, CGA 325′615, oxaziclomefone and AE F150944, which decreased the relative glucose incorporation into cellulose but increased it into tightly-bound cellulose fractions; and the third group, comprising flupoxam, triazofenamide and dichlobenil, decreased the relative glucose incorporation into cellulose and increased it into a pectin rich fraction

Consequences of dewatering cement mortars incorporated with ground Bayburt stone

The detrimental effects of the rapid dewatering of cement mortars due to the interaction of wet mortar and brick substrate at the freshly mixed state in masonry construction are often addressed in the literature. The desorptivity and hence very high water releasing ability of cement mortars result in a great water loss during dewatering that significantly affects the fresh and hardened state properties of the end product. The paper therefore investigates the possible role of ground Bayburt stone incorporation in cement mortars on dewatering characteristics and the consequences of this effect at the hardened state properties of these mortars in construction practice. The paper begins with the measurement of the parameters of water transport kinetics and individually reports the effect of dewatering on the mechanical properties and durability characteristic of cement mortars incorporated with ground Bayburt stones. The results reported in this paper strongly suggest that ground Bayburt stone incorporation in cement mortars significantly compensate the degree of dewatering, and this vital feature does not only decreases the influence of dewatering on mechanical properties but also results in an enhanced durability characteristics of cement mortars