pH sensitive polymer systems can be utilized as smart nanocarriers to deliver hydrophobic drugs specifically to solid tumors or to acidosis-affected rheumatic joints. In this study, a poly(L-aspartic acid-graftimidazole)-block-poly(ethylene glycol) (P(Asp-g-Im)-PEG) block copolymer was synthesized as a pH sensitive nanocarrier targeting acidic pH environments. The polypeptide P(Asp), which was used as a backbone for the hydrophobic block, was synthesized by ring opening polymerization with N-carboxylanhydride (NCA) of β-benzyl-aspartic acid. PEG was included as the hydrophilic block and the polymer was functionalized with imidazole groups to confer pH sensitivity. The prepared P(Asp-g-Im)-PEG is zwitterionic with a pI 6.5; 60% of the available carboxyl groups of P(Asp)-PEG were substituted by imidazole groups. Furthermore, the potentiometric titration curve of P(Asp-g-Im)-PEG demonstrated a broad buffer zone. The micelles prepared from P(Asp-g-Im)-PEG showed pH dependent critical micelle concentrations (CMC), particle sizes, zeta potentials, and morphologies.

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A lectin from the hemolymph of purse crab, Philyra pisum, was found to have anti-proliferative activity on human lung cancer cells by our laboratory. In this study, P. pisum lectin (PPL) was molecularly characterized including molecular mass, amino acid sequences, amino acid composition, and the effects of metal ions, temperature, and pH on the activity. W e found that PPL showed mitogenic activity on human lymphocytes and BALB/c mouse splenocytes. The mitogenic activity (maximum stimulation index, SI=9.57±0.59) of PPL on human lymphocytes was higher than that of a standard well-known plant mitogen, concanavalin A (maximum SI=8.80±0.59). The mitogenic activity mediated by PPL is required for optimum dosing, and higher or lower concentrations caused decreases in mitogenic response. PPL also induced mitogenic activity on mouse splenocytes, however, the maximum SI (1.77±0.09) on mouse splenocytes of PPL was lower than that (2.14±0.15) of concanavalin A. In conclusion, PPL is a metal ion-dependent monomer lectin with mitogenic activity, and could be used as a lymphocyte or splenocyte stimulator.

Compost has been widely used in order to promote vegetation growth in post-harvested and burned soils. The effects on soil microorganisms were scarcely known, so we performed the microbial analyses in a wildfire area of the Taebaek Mountains, Korea, during field surveys from May to September 2007. Using culture-dependent and -independent methods, we found that compost used in burned soils influenced a greater impact on soil fungi than bacteria. Compost-treated soils contained higher levels of antifungal strains in the genera Bacillus and Burkholderia than non-treated soils. When the antifungal activity of Burkholderia sp. strain O1a_RA002, which had been isolated from a compost-treated soil, was tested for the growth inhibition of bacteria and fungi isolated from burned soils, the membrane-filtered culture supernatant inhibited 19/37 fungal strains including soil fungi, Eupenicillium spp. and Devriesia americana; plant pathogens, Polyschema larviformis and Massaria platani; an animal pathogen, Mortierella verticillata; and an unidentified Ascomycota. However, this organism only inhibited 11/151 bacterial strains tested. These patterns were compatible with the culture-independent DGGE results, suggesting that the compost used in burned soils had a greater impact on soil fungi than bacteria through the promotion of the growth of antifungal bacteria. Our findings indicate that compost used in burned soils is effective in restoring soil conditions to a state closer to those of nearby unburned forest soils at the early stage of secondary succession.