An extracellular transglutaminase is required for apple pollen tube growth

An extracellular form of the calcium-dependent protein-cross-linking enzyme TGase (transglutaminase) was demonstrated to be involved in the apical growth of Malus domestica pollen tube. Apple pollen TGase and its substrates were co-localized within aggregates on the pollen tube surface, as determined by indirect immunofluorescence staining and the in situ cross-linking of fluorescently labelled substrates. TGase-specific inhibitors and an anti-TGase monoclonal antibody blocked pollen tube growth, whereas incorporation of a recombinant fluorescent mammalian TGase substrate (histidine-tagged green fluorescent protein: His6-Xpr-GFP) into the growing tube wall enhanced tube length and germination, consistent with a role of TGase as a modulator of cell wall building and strengthening. The secreted pollen TGase catalysed the cross-linking of both PAs (polyamines) into proteins (released by the pollen tube) and His6-Xpr-GFP into endogenous or exogenously added substrates. A similar distribution of TGase activity was observed in planta on pollen tubes germinating inside the style, consistent with a possible additional role for TGase in the interaction between the pollen tube and the style during fertilization.

Impact of liberalization on efficiency and productivity of sugar industry in Kenya

Purpose – The data used in this study is for the period 1980-2000. Almost midway through this period (in 1992), the Kenyan government liberalized the sugar industry and the role of the market increased, while the government's role with respect to control of prices, imports and other aspects in the sector declined. This exposed the local sugar manufacturers to external competition from other sugar producers, especially from the COMESA region. This study aims to find whether there were any changes in efficiency of production between the two periods (pre and post-liberalization). Design/methodology/approach – The study utilized two methodologies to efficiency estimation: data envelopment analysis (DEA) and the stochastic frontier. DEA uses mathematical programming techniques and does not impose any functional form on the data. However, it attributes all deviation from the mean function to inefficiencies. The stochastic frontier utilizes econometric techniques. Findings – The test for structural differences in the two periods does not show any statistically significant differences between the two periods. However, both methodologies show a decline in efficiency levels from 1992, with the lowest period experienced in 1998. From then on, efficiency levels began to increase. Originality/value – To the best of the authors' knowledge, this is the first paper to use both methodologies in the sugar industry in Kenya. It is shown that in industries where the noise (error) term is minimal (such as manufacturing), the DEA and stochastic frontier give similar results.

Solid-supported boronic acid conjugates for sugar and glycopeptide recognition

The Fmoc synthetic strategy was employed to synthesise two identical combinatorial peptide libraries on a hydrophilic PEG-PS resin. One library was appended with boronic acid moieties at two positionally-fixed locations. Successful inclusion of the boronic acid units was confirmed using a novel UV fluorescent colorimetric assay employing carminic acid as the dye compound. A study of the effect had by the resin-bound peptides bearing boronic acid groups on the binding characteristics of vancomycin, a medically relevant antibiotic glycoprotein, was conducted. In all, 132 library compounds were tested for their binding affinity with vancomycin, via immobilisation of the glycopeptide onto the solid support through hydrogen bonding or complexation with the boronic acid moieties. Subsequent cleavage via acidolysis afforded vancomycin containing solutions which were quantified by growth inhibition of methicillin susceptible Staphylococcus aureus. Comparison of the diameters of the resultant zones of inhibition and those produced by vancomycin of known concentrations afforded a means of calculating the vancomycin concentration of the cleavage solutions, and thereby determining the binding affinity of vancomycin to each peptide sequence. Five peptide sequences and twenty one of the peptidyl-boronic acid sequences showed zones of inhibition, demonstrating their reversible affinity for vancomycin. Three peptide sequences showed zones of inhibition in both libraries. The presence of boronic acid was therefore shown to impart, enhance, detract and remove the affinity of vancomycin to a range of resin-bound peptide sequences.

Biodeterioration of harvested sugar cane in Jamaica

The microbiological, physical and chemical changes which occur instored, harvested sugarcane were studied in Jamaica and the United Kingdom.The degree of deterioration was proportional to time of storage, and wasrevealed by a statistically significant reduction in sucrose content.Other symptoms included a fall in pH, and increases in reducing sugars,dextran, viscosity, and microbial count. Cut cane was universally infectedwith Leuconostoc mesenteroides, which reached a maximum count of 107 to 108organisms per ml. juice within. 3 to 4 days of harvest. Counts of othermicroorganisms were generally insignificant, except for occasional lactobacilli.A new dextran-forming species was named Lactobacillus confusus.Microorganisms isolated from deteriorated cane were screened for theirability to cause deterioration of a sterile, synthetic cane juice. L. mesenteroides strains were the most deteriogenic, but attempts toreproduce the symptoms of "sour" cane by inoculation of this organism intocut cane were only partially successful. L. mesenteroides was present in the soil and the epiphytic flora of the stalk. The principal vector of infection appeared to be the cutters' machete, especially in wet weather. Cane harvested by a chopper machine deteriorated more rapidly than hand-cut whole-stalks. Economic losses due to deterioration of harvested cane were estimated to be 9.2% of the initial recoverable sugar for the 1969 crop at Frome Estate, Jamaica. Dextran content was a useful indicator of cane biodeterioration. The dextran content of mill juices was correlated with rainfall, and significant correlations were obtained between dextran content and viscosity of mill syrups and the amount of sugar lost in final molasses; it also caused the formation of elongated crystals. Attempts to control sour cane by chemical and physical methods were unsuccessful, and it was concluded that the only solution is to mill cane within 24 hours of harvest. A novel method for removal of dextran from mill juices by enzymic treatment with dextranase was developed and patented.

Aggregation and caking processes of granular materials:continuum model and simulation with application to sugar

Aggregation and caking of particles are common severe problems in many operations and processing of granular materials, where granulated sugar is an important example. Prevention of aggregation and caking of granular materials requires a good understanding of moisture migration and caking mechanisms. In this paper, the modeling of solid bridge formation between particles is introduced, based on moisture migration of atmospheric moisture into containers packed with granular materials through vapor evaporation and condensation. A model for the caking process is then developed, based on the growth of liquid bridges (during condensation), and their hardening and subsequent creation of solid bridges (during evaporation). The predicted caking strengths agree well with some available experimental data on granulated sugar under storage conditions.