[Phagoresistance of filamentous cyanobacteria clones]. / Priroda fagorezistentnosti klonov nitchatykh tsianobacterii.

The paper deals with formation regularities of phagoresistant clones of cyanobacteria in two productive virus-cell systems: heterocyst cyanobacterium Nostoc linckia--cyanophage N-2, and mutant in heterocysts strain of Anabaena variabilis--cyanophage A-1. Frequency of spontaneous formation of phagoresistant clones of cyanobacterium N. linckia varies within 1.0-8.0 x 10(-6) per a cell, A. variabilis--5.0 x 10(-6)-7.0 x 10(-7) per cell. All the studied phagoresistant clones of N. linckia have identical morpho-cultural properties and do not differ from those of the initial culture. Phagoresistant clones of A. variabilis are presented by two groups. One of them, as to its properties, does not practically differ from the wild type culture. The second group differs considerably from the initial culture A. variabilis as to a number of characteristics--time of colonies appearance, their amount, length of trichomas, specific rate of growth and biomass accumulation. Spontaneous transfer of cyanophages to the culture liquid of clones resistant forms of cyanobacteria has not been revealed. Lysis of cells of the studied clones also was not induced under the effect of mytomycin C, thermal treatment and UV-irradiation. Cyanophage N-2 is not adsorbed by the cells of resistant cloned forms of cyanobacteria N. linckia. Only nonspecific adsorption takes place on the cells of phage-resistant clones of A. variabilis of both groups: about 20% of virions introduced in the adsorption mixture. Basing on the data obtained, it is supposed that phage-resistance of stable clones of filamentous cyanobacteria under the conditions of the given experiment is determined by the structure modification of cells receptors.

[Use of cyanobacteria for indication of toxic action of stachybotrys toxins]. / Vikorystannia tsianobakterii dlia indykatsiï toksychnoï diï stakhibotriotoksyniv.

Screening of cyanobacteria cultures for their sensitivity to the action of complex preparations of toxins from 18 strains of Stachybotrys chartarum has been carried out with the purpose to search for new test-organisms to create a reliable system of biotesting of stachibotryotoxines. In contrast to other cultures of unicell (Anacystis nidulans) and filamentous (Anabaena sp., Anabaena variabilis, Nostoc linckia, Plectonema boryanum) cyanobacteria used in the experiment, only one culture of unicell cyanobacterium Synechococcus cedrorum proved to be highly sensitive to the action of preparations of the whole group of studied mycotoxins. Their activity with respect to this culture varied within wide limits (lysis zone diameter is 11-30 mm) and for the most of strains it coincided with or exceeded this index determined with the use of other biotests. Owing to the use of Synechococcus cedrorum as test culture the authors have proved for the first time the toxicity of three strains of Stachybotrys chartarum (K15822, 14722, 14186). Basing on the data obtained the authors have determined the culture of the unicell cyanobacterium, according to the sign of high sensitivity to all the studied stachibotryotoxin preparations of solid and liquid nutrient media, as a new test-organism for detection of this group of toxins and it may be recommended for practical use. Optimal conditions for growing test-culture and biotesting of toxins have been defined.

[Activity of tricarboxylic acid cycle enzymes in cyanobacteria Spirulina platensis]. / Izuchenie aktivnosti fermentov tsikla trikarbonovykh kislot tsianobacterii Spirulina platensis.

The activity level and some physico-chemical properties of enzymes of the tricarboxylic acid cycle (TCA cycle) and the associated enzymes isocitrate lyase and glutamate dehydrogenase of cyanobacterium Spirulina platensis grown under illumination of 5000 lk in batch conditions, have been studied. High activities of most of the studied enzymes except for alpha-ketoglutarate dehydrogenase (alpha-KGDH) and succinate dehydrogenase have been estimated. In some cases the activities were by an order higher than that of similar enzymes in other cyanobacteria. This reflects the microorganism ability to synthesize intensively organic substances and first of all protein. Absence of alpha-KGDH activity proves that TCA cycle of spirulina has a limited value for energy generation and mainly performs the biosynthetic function.

[The resistance of the DNA of cyanophage LPP-3 to the action of different restriction endonucleases]. / Rezistentnost' DNK tsianofaga LPP-3 k deistviiu razlichnykh éndonukleaz restriktsii.

Data on the study of structure peculiarities of cyanophage LPP-3 DNA are presented in the work. The length of cyanophage DNA calculated by means of the enzymatic hydrolysis by restrictases is 40 +/- 3.5 thou. pairs of bases. Cyanophage LPP-3 DNA was hydrolysed by more than 50 different restrictases. As a result of screening it was found out that the great number of restrictases, which recognized hexanucleotide sequences did not hydrolyze DNA of cyanophage LPP-3. A considerable deviation of the number of the observed sites of restriction from their theoretically expected number for restrictases Hae III and Cfr 131 was established. Restrictases-isoschisomeres with different sensitivity to the methylation of the recognition sites--Msp I, Hpa II and Sau 3A, MboI and DpnI were used to check the availability of methylated bases in LPP-3 DNA. Absence of methylated adenine in the site GATC and methylated cytosine in the second position of the site CCGG were established. The results obtained permit supposing that the expressed counterselection by the sites of recognition of many restriction endonucleases takes place in cyanophage LPP-3 DNA. It is supposed that apparently, this method of protection of its genome in LPP-3 is one of most important but the inconsiderable percentage of site-specific methylation of the virus DNA cannot be completely excluded.