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The review deals with analysis of the possibility of the use of genes of inhibitors of proteolytic enzymes of plants to increase plant tolerance to insect pests and phytopathogens. The idea of using protease inhibitors for plant defense is strongly supported, first, by their wide distribution in plant tissues and high activity towards various proteolytic enzymes of insects, bacteria and fungi. The results obtained for the last years indicate that the genetic engineering approach is perspective for solving of this kind of problems. The main losses and advantages of the discussed approach are also considered. The described approach for increase of plant tolerance to insects and pathogens has few advantages as compared to traditional ones and belongs to ecologically pure technologies.

A new procedure for isolation of purified nuclear fraction from the cells of the phytoflagellatum Astasia longa has been developed. The resulting preparations were characterized in terms of their chemical composition. A method of isolation to total histone preparations from the nuclear fractions of A. longa based on the metabolic peculiarities of the phytoflagellatum has been developed. Pure histone fractions were obtained by intensive disruption and thorough washing of the nuclear fraction from the non-histone proteins with weak solutions of salts. The intensive proteolysis of the histones in the course of washing was stopped by an addition of the specific inhibitors of proteinases--phenylmethylsulfanylfluoride and pCMB (pH 7,8--8,0). The use of NaHSO3 or boiling of the nuclear fraction to suppress the histone proteolysis were found to be ineffective. Extraction of the histones by 1 M CaCl2 appeared more productive than the use of mineral acids solutions. The total histone preparation isolated under optimal conditions was found in the chromatin in amounts equivalent to those of DNA; its amino acid composition was typical for histones. During polyacrylamide gel electrophoresis in an acidic system in the presence of urea the histones produced four main bands, whereas in the presence of DS-Na--five bands. In terms of the amino acid composition and electrophoretic properties in different systems the histones of A. longa are similar but not identical to calf thymus histones.

A preparation of total histones has been isolated for the first time from the purified fractions of T. lewisi cell nuclei and characterized in terms of its chemical composition and RNA-polymerase activity. A special attention during the isolation procedure was given to the repression of proteolytic degradation of the histones. The amount of protein in the chromatin is equivalent to that of DNA. The amino acid composition and heterogeneity of the protein during polyacrylamide gel electrophoresis in an acid system and in the presence of sodium dodecyl sulfate are typical for histones. Using two-dimensional electrophoresis, differential staining of electrophoregrams and ion-exchange chromatography on CM-cellulose the total preparation has been found to be made up of five fractions: two -- arginine-rich (one of them identical to histone H4, the other being similar to histone H3 from calf thymus); two -- moderately lysine-rich fractions, slightly differing in their properties from histones H2A and H2B from calf thymus, and one specific fraction with mol. weight of 16 000 and an extremely high positive charge. The above methods in combination with specific extraction have been used to demonstrate the absence of a typical lysine histone in the preparation, which is correlated with the absence of typical methaphase chromosomes during mitosis in T. lewisi.