[mRNA for the plasminogen activator of the urokinase type: translation in oocytes of Xenopus laevis]. / mRNK aktivatora plazminogena urokinaznogo tipa: transliatsiia v ootsitakh Xenopus laevis.

Poly(A)+-RNA from human kidney and human embryonal lung fibroblasts fractionated by sucrose gradient centrifugation was translated in Xenopus oocytes. Assay for plasminogen-dependent fibrinolytic activity detected synthesis of secreted plasminogen activator and revealed the active fraction of poly(A)+-RNA with a sedimentation coefficient of approximately 23S. Translation products of the active fraction were immunoadsorbed by antiurokinase monoclonal antibodies immobilized on sepharose. Gel electrophoretic analysis of the protein products showed that the 23S fraction of poly(A)+-RNA from human kidney contains mRNA for single-chain urokinase-type plasminogen activator with apparent molecular weight of approximately 50 kDa.

[Non-specific RNA degradation in the presence of magnesium ions]. / Nespetsificheskaia degradatsiia RNK v prisutstvii ionov magniia.

RNA degradation catalyzed by Mg2+ was studied under the conditions of reverse transcriptase reaction. Agarose gel electrophoresis in 6 M urea was employed to follow the reaction. Natural ribosomal of poly(A)+ RNA as well as synthetic poly(rA) are equally accessible for degradation. Neither an RNAase nor alkali alone is responsible for the degradation. The reaction rate is directly proportional to Mg2+ concentration in the range of 1 to 10 mM, doesn't depend upon RNA concentration and enhances approximately 50 fold upon increasing of pH value from 7.5 to 9.0. It was concluded that the Mg2+ catalyzed degradation reaction is an unspecific one in respect to the primary structure of RNA. The results obtained are useful to optimize the conditions for the reverse transcriptase reaction.

[Isolation and characteristics of urokinase-type plasminogen activator from a culture of human embryo lung fibroblasts]. / Vydelenie i kharakteristika aktivatora plazminogena urokinaznogo tipa iz kul'tury legochnykh fibroblastov émbriona cheloveka.

Plasminogen activator from conditioned medium of human embryonal lung fibroblasts was purified by phosphocellulose P11 chromatography, followed by p-aminobenzamidine-agarose chromatography. Two forms of plasminogen activators were separated by chromatography on the heparin-sepharose. The high molecular weight form (53 kDa) with specific activity 130 000 IU/mg consists of two polypeptide chains (31 kDa and 20 kDa) and exhibits strong affinity for fibrin-celite, lysine-sepharose and heparin-sepharose. The low molecular weight form (32 kDa, 190 000 IU/mg) also binds to these sorbents, but more weakly, and its properties are very similar to those of low molecular weight urokinase. Activity of both forms of plasminogen activators are inhibited by monoclonal antibodies against urokinase. A number of enzymological chromatographic and immunological properties indicates, that the plasminogen activator from lung fibroblasts is of urokinase type.

[Effect of tetanus toxin on K+ and Na+ concentration in synaptosomes]. / Vliianie stolbniachnogo toksina na soderzhanie K+ i Na+ v sinaptosomakh.

A study was made of the effect of tetanus toxin (TT) in doses of 20-1000 MLD (for rats) on synaptosomes isolated from the rat brain cortex. TT produced a decrease in K+ content in synaptosomes. The effect depended on the dose of TT (I50=22 MLD). The content of Na+ remained unchanged. The action of TT depended on the time and the maximal effect was seen upon 60 minutes of incubation. TT inactivated by boiling or by antitoxin did not affect K+ content in synaptosomes. An increase of K+ concentration up to 17 mM in an incubation medium led to an increase in K+ content in TT-poisoned synaptosomes but not in the control ones. Possible changes in membrane electrogenesis in nerve terminals caused by TT are discussed.