[Formation of giant and ultramicroscopic forms of Nostoc muscorum CALU 304 during cocultivation with Rauwolfia tissues]. / Obrazovanie gigantskikh i ultramikroform Nostoc muscorum CALU 304 pri vzaimodeistvii s kul'tiviruemymi tkaniami rauvol'fii.

The study of heteromorphic Nostoc muscorum CALU 304 cells, whose formation was induced by 6- to 7-week cocultivation with the Rauwolfia callus tissues under unfavorable conditions, revealed the occurrence of giant cell forms (GCFs) with a volume which was 35-210 times greater than that of standard cyanobacterial cells. Some GCFs had an impaired structure of the murein layer of the cell wall, which resulted in the degree of impairment of the cell wall ranging from the mere loss of its rigidity to its profound degeneration with the retention of only small peptidoglycan fragments. An analysis of thin sections showed that all GCFs had enlarged nucleoids. The photosynthetic membranes of spheroplast-like GCFs formed vesicles with the contents analogous to that of nucleoids (DNA strands and ribosomes). About 60% of the vesicles had a size exceeding 300 nm. With the degradation of GCFs, the vesicles appeared in the intercellular slimy matrix. It is suggested that the vesicles are analogous to elementary bodies, which are the minimal and likely primary reproductive elements of L-forms. The data obtained in this study indicate that such L-forms may be produced in the populations of the cyanobionts of natural and model syncyanoses. Along with the other known cyanobacterial forms induced by macrosymbionts, L-forms may represent specific adaptive cell forms generated in response to the action of plant symbionts.

[Characteristics of infection of plants and their cultured tissue with cyanobacterial-bacterial symbiotic associations]. / Osobennosti infitsirovaniia rastenii i ikh kul'tiviruemykh tkanei assotsiativnymi tsianobakterial'no-bakterial'nymi kompleksami mikrosimbiontov.

The infection of tobacco, nightshade, rice plants, and their tissue cultures with the cyanobacteria-bacteria symbiotic associations (CBSA) isolated from natural syncyanoses (the ferns Azolla pinnata and Azolla sp. and the cycad Encephalartos ferox) was studied. The inoculation of the intact plants or their cuttings with CBSA led to the colonization of the plant roots, stems, and leaves by cyanobacteria and their bacterial symbionts (referred to as satellite bacteria, SB). The sites of the long-term contact of plant organs with cyanobacteria were characterized by the formation of copious slime. On the roots of infected plants, one could observe the callus growth of cortical parenchyma cells and the formation of pseudonodules, in which SB cells gradually accumulated. In mixed cultures of plant callus tissues and the CBSA isolated from the ferns A. pinnata and Azolla sp., the callus tissue specifically influenced the growth of the CBSA components, causing (depending on the plant species and strain) either their balanced growth, or their cyclic growth, or the predominant growth of one of the CBSA components (either cyanobacteria or satellite bacteria). This phenomenon is proposed to be used for the dissociation of stable multicomponent natural symbiotic complexes and the selection of their particular components.

[Features of cyanobacterial-bacterial complexes of microsymbionts of plant syncyanoses]. / Osobennosti tsianobakterial'no-bakterial'nykh kompleksov mikrosimbiontov rastitel'nykh sintsianozov.

The morphology and ultrastructure of associative microsymbiont complexes (AMC) isolated from the ferns Azolla pinnata and Azolla sp. and the apogeotropic roots of the cycad Cycas revoluta were studied. The composition of the AMC obtained includes the cyanobionts (symbiotic cyanobacteria) and satellite bacteria (SB). It was found that two types of cyanobacteria that substantially differ in their morphological organization are likely present as cyanobionts in the coralloids of C. revoluta. The isolated cyanobiont strains exhibited the morphological traits and regularities of development typical of the genus Nostoc; they were characterized by the ability of their cells to divide in mutually perpendicular planes. When isolating AMC from different morphological zones of C. revoluta apogeotropic roots, SB growth was revealed only around the pieces corresponding to the coralloid apical zone. No AMC components were revealed around the segments of the basal growth zone. Pure cyanobiont cultures were obtained from the AMC of C. revoluta coralloids. The AMC isolated from the ferns A. pinnata and Azolla sp. are characterized by obligate mutual dependence of the partners (the cyanobiont and SB).

[Electron microscopic study of dark and photo-oxidative degradation of the blue-green alga Anabaena variabilis]. / Elektronno-mikroskopicheskoe izuchenie temnovoi i fotookislitel'noi degradatsii sine-zelenoi vodorosli Anabaena variabilis

Changes in the cell ultrastructure were studied during incubation of the obligate phototrophic blue-green alga Anabaena variabilis in the dark for a long time. The cells lost viability though their cell wall and cytoplasmic membrane were preserved; however, certain regions of the mureine layer were thickened in some cells. The membranes of the photosynthetic apparatus separate forming intrathylakoid spaces and the cytoplasm density decreases revealing phycobilisomes. During incubation in the dark for a long time, polyglucoside alpha-granules in the cytoplasm disappear, polyhedral bodies are preserved, and numerous large granules of average electron density and unknown nature appear. Transfer of the culture from the dark to the light when the cells are losing their viability results in intensive destruction of the thylakoids. Loss of viability by the cells of Anabaena variabilis in the dark is supposed to be due to irreversible damages of the membranes of the photosynthetic apparatus in these conditions.

[Photodestruction of the blue-green alga Anabaena variablis]. / Fotodestruktsiia sine-zelenoi vodorosl Anabaena variablis

The effect of light on the cells was studied with the obligate phototrophic blue-green alga Anabaena variabilis after its incubation in the dark. Incubation of the alga in the dark during two weeks was not essential for the cell reproduction systems in the light. Incubation in the dark during 3-4 weeks caused damages in the systems which were however reversible and repaired in the light. Longer incubation of the cells in the dark results in irreversible damages of the systems protecting them from photooxidation which may be the main factor preventing growth of the cells in the light.

[Metabolism and destruction of the blue-green alga Anabaena variablis in the dark]. / Metabolism i destruktsiia sine-zelenoi vodorosli Anabaena variablis v temnote

Anabaena variabilis remains viable in the dark, which is accompanied with intensive utilization of the reserve polysaccharide by the cells. The content of protein and RNA increases in the cells and incomplete cellular division occurs at the beginning of the culture incubation in the dark. Destruction of the intracellular protein and RNA begins before all the reserve polysaccharide has been utilized. During the whole period of incubation of the alga in the dark, structural integrity of the cells is preserved though the intracellular components are destroyed. Further incubation in the dark results in a complete lysis of the culture. Destruction in the intact cells does not involve DNA whose total content in the culture decreases only by the beginning of lytic processes.

[Comparative study of the functions of the spheroplasts and cells of the blue-green alga Anabaena variabilis]. / Sravitel'now izuchenie funktsii sferoplastov i kletok sine-zelenoi vodorosli Anabaena variabilis

The effect of light was studied with the spheroplasts of the blue-green alga Anabaena variabilis. Contrary to the intact cells, the spheroplasts did not synthesize nucleic acids and pigments in the light. These components of the spheroplasts were decomposed in the light, and the remaining chlorophyll was incapable of luminescence. The rate of oxygen uptake increased upon the incubation of the spheroplasts in the light. Changes of the functions induced by lysozyme in the cells of A. variabilis are irreversible, contrary to those which are caused by the incubation in the darkness and can be restored if the cells are transferred into the light.

[Electron microscopic and biochemical study of spheroplasts of the blue-green alga Anabaena variabilis]. / Elektronno-mikroskopicheskoe i biodhimicheskoe izuchenie sferoplastov sine-zelenoi vodorosli Anabaena variabilis

Electron microscopy of the spheroplasts of the blue-green alga Anabaena variabilis revealed damages induced by lysozyme. Biochemical analysis confirmed the data of electron microscopy that the spheroplasts had lost partly the cytoplasmic content of the cells. DNA was preserved in the spheroplasts though the nucleoid was not detected by electron microscopy.