Design of liposome to improve encapsulation efficiency of gelonin and its effect on immunoreactivity and ribosome inactivating property

Gelonin, purified from the seeds of Gelonium multiflorum, using cation-exchange and gel-filtration chromatography was characterised for its purity, homogeneity and molecular weight by reverse-phase HPLC (RP-HPLC) and SDS-PAGE analysis. The HPLC purified gelonin was used for entrapment studies in the liposomes. Liposomes were prepared by reverse phase evaporation (REV) technique using three different types of lipid composition in the same molar ratio. The method resulted in 75–80% entrapment efficiency of gelonin in the liposomes. Entrapped and unentrapped gelonin was characterized for physico-chemical, immunochemical and biological properties. The immunoreactivity of entrapped gelonin was fully preserved but the ribosome-inactivating property was slightly inhibited. The method involved mild conditions, highly reproducible and the liposomes produced appeared to be stable for several months. It has important implications in the development of cell type specific cytotoxic agents where a chemical cross-linking is involved which significantly inhibits both immunoreactivity and ribosome-inactivating ability of the toxin.     

Chromosomal anomalies induced by the organic phosphate pesticide guthion in Chinese hamster cells

Chromosomal anomalies associated with the use of the organic phosphate pesticide guthion were investigated in Chinese hamster cells (line CHO-K1). Most commonly observed were chromatid breaks and exchanges. Infrequently, mild failure of condensation, despiralization, secondary constriction, gaps, pulverization, ring and dicentric chromosomes were noted. The mean number of chromosome breaks per cell was significantly higher in treated cells than in control cells. Autoradiographic studies revealed that while higher dosages of the chemical (80–120 μg/ml) arrested cells and prevented their movement out of S phase, a lower dosage (60 μg/ml) caused a progression delay. In relation to the relative length of no. 1 and no. 2 chromosomes, no apparent difference existed in the incidence of total breaks between them. However, significant differences in the nonrandom distribution of breaks in no. 1 and no. 2 chromosomes indicated linear differentiation of breakage susceptibility along the chromosomes. An increased concentration of breaks was observed in the long arms of both no. 1 and no. 2 chromosomes. The experimental results suggest that guthion, as well as inducing chromosomal anomalies, may produce a viable mutant.     

Effect of carbohydrates on the growth ofRhizoctonia solani Kühn

The growth OfRhizoctonia solani in different carbohydrates was studied. The rate of growth of the fungus was traced by taking the dry weights of mycelia obtained from the carbohydrate medium at regular intervals and shifts in the pH were recorded. Different carbohydrate sources had different effects on the growth of the organism. The exoenzymes from the organism were capable of cleaving carbohydrates irrespective of whether the fungus grew in them or not.     

A model for formulation of protein assay.

The principle of the protein assay using the reaction of an alkaline copper-protein complex with the Folin-Ciocalteu phenol reagent has been investigated. In contrast to the long-established Lowry method, a stable and rapid protein assay is developed without a buffering agent in alkaline copper solution. In the absence of a buffering agent, the reaction pH drops relatively rapidly and moves the reaction toward a more stable pH. When the reaction of alkaline copper-protein complex with Folin-Ciocalteu reagent is started at around pH 11.7, the reaction color absorbance reaches a plateau in approximately 10 min and remains stable to allow a reliable measurement of the absorbance. In the absence of the buffering agent sodium carbonate, the alkaline copper solution is also stable for months. The principle of the protein assay is presented as a model that can be used to formulate protein assays of desired specification.     

Oil palm (Elaeis guineensis) protoplasts: isolation, culture and microcallus formation

Procedures are deseribed for the efficient isolation of protoplasts from a variety of oil palm (Elaeis guineensis Jacq.) tissues. Various factors including donor source, composition of enzyme mixture and culture medium affected the yield and viability of the protoplasts Polyembryogenic cultures of oil palm were the most suitable starting material in terms of yield, viability and metabolic competence. Pectolyase Y-23 in association with cellulase and hemicellulase was required for the efficient release of protoplasts from the oil palm tissues. Limited cell division to form microcallus was observed at very low frequency (<0.01%) when glutathione and catalase were incorporated in the culture medium.Abbreviations 2,4-d dichlorophenoxyacetic acid - DTT dithiothreitol - MES 2[N-morpholino] ethanesulphonic acid - NAA 1-naphthalene acetic acid - PVP polyvinylpyrrolidone     

Tetracyclines modulate cytosolic Ca2+ responses in the osteoclast associated with “Ca2+ receptor” activation

We report the effects of tetracycline analogues on cytosolic Ca²⁺ transients resulting from application of ionic nickel (Ni²⁺), a potent surrogate agonist of the osteoclast Ca²⁺ receptor. Preincubation with minocycline (1 mg/l) or a chemically modified tetracycline, 4-dedimethyl-aminotetracycline (CMT-1) (1 or 10 mg/l), resulted in a significant attenuation of the magnitude of the cytosolic [Ca²⁺] response to an application of 5 mM-[Ni²⁺]. Preincubation with doxycycline (1 or 10 mg/l) failed to produce similar results. In addition, application of minocycline alone (0.1–100 mg/l) resulted in a 3.5-fold elevation of cytosolic [Ca²⁺]. The results suggest a novel action of tetracyclines on the osteoclast Ca²⁺ receptor.