The induction of tumour cell adhesiveness and intercellular junctions by a glycoprotein of rat ascites hepatoma cell surface

Rat ascites hepatoma AH109A cells (present as a free form in vivo) can aggregate and then develop well-defined tripartite junctional complexes, including intermediate junctions, desmosomes and focal tight junctions, on incubation with a glycoprotein separated from rat ascites hepatoma AH136B cells (forming cell islnds in vivo). The development of binding structures was strongly inhibited by actinomycin D. AH109A cells or rat ascites hepatoma YS cells (present as a free form in vivo) previously treated with the glycoprotein for 24 h, when inoculated i.p., proliferated as free cells in the ascitic fluid, like the untreated cells. AH109A cells actively proliferating in the skin do not form any junctional complexes. The reason for the failure of island formation by AH109A cells or YS cells in vivo is discussed.

Release of chymotrypsin-like esterase from isolated rat peritoneal mast cells by arginine-rich calf thymus histone

Release of chymotrypsin-like esterase from isolated rat peritoneal mast cells by arginine-rich and lysine-rich calf thymus histones was investigated. The arginine-rich histone released the esterase, but the lysine-rich histone did not release the esterase from the mast cells. The isolated mast cells spontaneously released the esterase gradually. The chymotrypsin-like esterase released from the mast cells is considered to digest the destructed material in tissues in a state of chronic destruction, such as chronically inflamed tissues and malignant tumours.

Studies on lipase from Mucor javanicus. I. Purification and properties

1. Lipase produced by a mold, Mucor javanicus, was purified about 180-fold from the ethanol precipitate of the culture filtrate. Purification was achieved by acid precipitation followed by gel filtrations on Sephadex G-200 (at low ionic strength) and Sephadex G-75 (at a high ionic strength). The purified enzyme preparation showed unusual behavior on polyacrylamide gel electrophoresis. The molecular weight was estimated to be 21 000. The enzyme had a positional specificity towards the position 1 and 3 of triacylglycerols. 2. Lipase in the crude preparation takes an aggregated form. aggregated form was achieved by raising the ionic strength of the medium. 3. The purified lipase preparation from Mucor javanicus exhibits phospholipase A1 activity, hydrolyzing the carboxyl ester at the 1-position of phosphatidylcholine. This activity seems to be due to the action of the lipase itself and not due to any other specific phospholipases.

A rapid modified gas chromatographic assay for esterase activity

A rapid modified procedure for the gas chromatogrpahic determination of esterase activity was studied. Aliphatic esters such as ethyl n-butyrate, n-propul n-butyrate, n-butyl n-butyrate and n-amyl n-butyrate were used as substrates and acetone was chosen as the most suitable solvent for dissolving the substrates in order to avoid alcoholysis. The enzyme reaction was started in a mixture of 0.03 M phosphate buffer, pH 7.90, containing an adequals, an aliquot of the reaction solutionwas injected directly on to a gas chromatograph and the alcohols produced were separated.

An electron microscopic study of tumour cell adhesiveness induced by aggregation promoting factor from rat ascites hepatoma cells

A substance capable of inducing tumour cell aggregation, which is supposed to be a glycoprotein showing noncytotoxicity, was separated from rat ascites hepatoma cells and partially purified by chromatography. Adhesiveness of rat ascites hepatoma cells induced by this substance was characterized by gradual development of known binding structures during a period of 24 h after contact with the substance; simple apposition and intermediate junctions developed in the early stage, and desmosomes and focal tight junctions in the later stage. It was assumed that the substance might be involved in the development of such binding structures as a triggering mechanism of tumour cell adhesiveness.