Localization of Associative Cyanobacteria on the Roots of Epiphytic Orchids

This work is the first study of the localization of phototrophic microorganisms in the rhizoplane and velamen of epiphytic orchids, namely, on the aerial and substrate roots of Acampe papillosa and Dendrobium moschatum and on the aerial roots of Phalaenopsis amabilis and Dendrobium phalaenopsis. The composition of the bacterial community on the plant roots depended on the conditions of plant growth. Under conditions simulating the climate of moist tropical forests, the aerial roots proved to be populated with phototrophic microorganisms, among which cyanobacteria predominated. Interlaced fungal hyphae and filamentous cyanobacteria formed a sheath on the surface of the aerial roots. The nitrogen-fixing capacity of the sheath of the aerial roots was studied on the example of P. amabilis.     

The characterization of lectins from the thripartite lichen <Emphasis Type="Italic">Peltigera aphthosa</Emphasis> (L.) Willd.

Agglutinin from Pemtigera aphthosa (L.) Willd. was isolated and its characteristics were obtained. It is a glycoprotein lectin with D-galactose specificity. Lectin concentration decreases from the apical parts of the thallus to its basal region. Finer differences in the agglutinating activity of different parts of the thallus reflect physiological differences in certain areas and their role in the functioning of lichen symbiosis.     

Erratum to: Characteristics of Vacuolar Inclusions in Coelastrella rubescens Namsu R1 Green Microalgae Cells in Low- and High-Intensity Light

Russian Journal of Plant Physiology - Under the growth experiment, the effect of zinc deficiency in the substrate on a number of growth of barley parameters, the state of the photosynthetic...     

Bioluminescent Toxicity Assay of Polyethylenimine-Based Sorbents

Applied Biochemistry and Microbiology - The toxicity of polyethylenimine-based sorbents and their extracts was evaluated, and their effect on the bioluminescence of Photobacterium phosphoreum...     

Microbial Complexes Occurring on the Apogeotropic Roots and in the Rhizosphere of Cycad Plants

The microbial complexes of soil, the rhizosphere, and the rhizoplane of the apogeotropic (coralloid) roots of cycad plants were comparatively studied. The aseptically prepared homogenates of the surface-sterilized coralloid roots did not contain bacterial microsymbiont, indicating that in the root tissues the symbiosis is a two-component one (plant–cyanobacteria). At the same time, associated bacteria belonging to different taxonomic groups were detected in increasing amounts in the cycad rhizoplane, rhizosphere, and the surrounding soil. The bacterial communities found in the cycad rhizoplane and the surrounding soil were dominated by bacteria from the genus Bacillus. The saprotrophic bacteria and fungi colonizing the cycad rhizosphere and rhizoplane were dominated by microorganisms capable of degrading the plant cell walls. The local degradation of the cell wall was actually observed on the micrographs of the thin sections of cycad roots in the form of channels through which symbiotic cyanobacterial filaments can penetrate into the cortical parenchyma.     

Experimental lichenology

Experimental methods in lichenology are summarized, the most attention being paid to the synthetic and cultural methods. Synthetic methods are based on the several stages: induction of dissociation of the natural lichen thallus to the monocultures of symbionts, culturing of these symbionts, and subsequent resynthesis under controlled conditions. Synthesis of the model association is based on monocultures of one of the symbionts and free-living organisms. These methods allow studying specificity and selectivity of interactions among symbionts, morphogenesis of the lichen thallus, and the role of minor components of the symbiotic system. Cultural methods involve development of dedifferentiated cell aggregates of lichen thallus ("lichen tissue cultures") on the solid and liquid media. At present, the methods of maintenance of lichen tissue cultures on the solid medium are worked out only. However, the lichen tissue cultures on the liquid medium are much more interesting because this method can be introduced in biotechnology. Cultural methods allow to achieve lichen biomass that contain specific lichen compounds. Induction of morphogenesis in lichen tissue cultures is possible.     

Melafen action on the growth of cyanobacteria and green microalgae cultured in stress conditions

Melafen stimulating effect on cell growth of cyanobacteria Synechococcus sp. PCC 6301 cultures amounted to 30–45% at 1000 lx illumination. The melafen effect decreased when cell cultures were exposed at the illumination of the saturation range (4000 lx). Growth rate and biomass increase of Anabaena variabilis, as well as the observed melafen stimulating effect, were higher on nitrogen-free medium compared to a nitrogen-containing one by 20–25%. We conclude that melafen activates photosynthetic processes and, probably, stimulates fixation of the atmospheric nitrogen in the cells. Opposite to the stimulating effect of melafen, ions of the heavy metal Cd²⁺ inhibited both biomass increase and the average number of the cells in the cyanobacteria A. variabilis colonies. The melafen added to the medium together with the Cd²⁺ ions decreased their negative effect. The other heavy metal ions, Cu²⁺, inhibited the growth of the cyanobacteria Synechococcus sp. PCC 6301 and green microalgae Chlorella vulgaris but had a stimulation effect on carbohydrate excretion by the cell cultures. Again, the melafen decreased the toxic effect of Cu²⁺ in this case. We suppose that melafen has an antistress activity at heavy metal ions presence and reduces their toxic effect on growth of phototrophic microorganisms.     

Associations between the White Sea invertebrates and oxygen-evolving phototrophic microorganisms

Eleven species of White Sea invertebrates (sponges, actinians, hydroids, polychaetes, and nudibranch mollusks) were tested for the presence of associated oxygen-evolving phototrophic microorganisms (OPM) (microalgae and cyanobacteria). Two main approaches were applied: (a) light and electron microscopy of intact samples and fixed preparations of invertebrates, and (b) isolation of microorganisms from samples of invertebrates after mild surface sterilization. The obtained results lead to conclusions on the formation of multicomponent associations by White Sea invertebrates and OPM based on the following data: (1) isolation of 27 cultures of OPM from eight species of invertebrates (sponges, hydroids, polychaete trochophore larva), (2) specificity of association between epibiontic communities of microorganisms and macroorganisms within the same biotope, and (3) spatial integration of micro- and macropartners resulting in the formation of morphological structures within the interorganismic contact zones.     

Accumulation of pyrophosphate and other energy-rich phosphorus compounds under various conditions of yeast growth

In the cells of hybrid yeast strain Saccharomyces N.C.Y.C. 644 SU₃ (Karlsberg collection), a large amount of pyrophosphate (30–300 mol/g of dry weight) accumulates whatever the aeration conditions and the content of glucose in the medium. The content of pyrophosphate is 10–1000 times higher than that of ATP. At the early and mid-exponential growth phases two maxima of pyrophosphate accumulation are observable. The periods of maximal pyrophosphate accumulation in yeast coincide with those of the minimal content of polymeric acid-soluble polyphosphates and intense budding. In the light of the data obtained, the question is discussed as to the relationship between the metabolism of pyrophosphates and acid-soluble polyphosphates in yeast.     

Dichroic ratio as the characteristic of the functional condition of the system

The principal deviation between parameters of spectral characteristics of surface structures and whole cells of unicellular algae Dunaliella tertiolecta and Tetraselmis viridis before and after influence of electromagnetic field (EMF) has been determined. It was found that the dichroic ratio can characterize the degree of adaptation of the culture to changing conditions of the environment.