From germinating pollen of lily, two types of villins, P-115-ABP and P-135-ABP, have been identified biochemically. Ca(2+)-CaM-dependent actin-filament binding and bundling activities have been demonstrated for both villins previously. Here, we examined the effects of lily villins on the polymerization and depolymerization of actin. P-115-ABP and P-135-ABP present in a crude protein extract prepared from germinating pollen bound to a DNase I affinity column in a Ca(2+)-dependent manner. Purified P-135-ABP reduced the lag period that precedes actin filament polymerization from monomers in the presence of either Ca(2+) or Ca(2+)-CaM. These results indicated that P-135-ABP can form a complex with G-actin in the presence of Ca(2+) and this complex acts as a nucleus for polymerization of actin filaments. However, the nucleation activity of P-135-ABP is probably not relevant in vivo because the assembly of G-actin saturated with profilin, a situation that mimics conditions found in pollen, was not accelerated in the presence of P-135-ABP. P-135-ABP also enhanced the depolymerization of actin filaments during dilution-mediated disassembly. Growth from filament barbed ends in the presence of Ca(2+)-CaM was also prevented, consistent with filament capping activity. These results suggested that lily villin is involved not only in the arrangement of actin filaments into bundles in the basal and shank region of the pollen tube, but also in regulating and modulating actin dynamics through its capping and depolymerization (or fragmentation) activities in the apical region of the pollen tube, where there is a relatively high concentration of Ca(2+).
In this work, the authors have studied a method for the improvement of the generating efficiency of a gas-turbine combined-cycle system (GTCC) using by-product gas (pretreated blast-furnace gas). The generating efficiency of by-product-gas-fired GTCC is 7 % lower than that of LNG-fired GTCC at a combustion temperature of 1623 K. The generating efficiency of the gas-separation energy was improved by +5.5 % (η=48.8→54.3 %) by removing CO 2 and N 2 from the blast-furnace gas. If this innovative system were applied to steelworks around the world, the potential electricity generation would be 69 billion kWh/year. This would mean a reduction of Δ56 million t-CO 2 /year.Key Words : Gas Turbine Combined Cycle, Gas Separation, Simulation, Blast Furnace Gas, Generating Efficiency
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