Molecular identification and ultrastructural and phylogenetic studies of cyanobacteria from association with the white sea hydroid Dynamena pumila (L., 1758).

Three new cyanobacterial strains, that have been previously purified from the hydroid Dynamena pumila (L., 1758), isolated from the White Sea, were studied using scanning and transmission electron microscopy methods and were characterized by using almost complete sequence of the 16S rRNA gene, internal transcribed spacer 16S-23S rRNA, and part of the gene for 23S rRNA. The full nucleotide sequences of the rRNA gene clusters were deposited to GenBank (HM064496.1, GU265558.1, JQ259187.1). Comparison of rRNA gene cluster sequences of Synechococcus cyanobacterium 1Dp66E-1, Oscillatoriales cyanobacterium 2Dp86E, and Nostoc sp. 10Dp66E with all sequences present at the GenBank shows that these cyanobacterial strains do not have 100% identity with any organisms investigated previously. Furthermore, for the first time heterotrophic bacterium, associated with Nostoc sp. 10Dp66E, was identified as a member of the new phylum Gemmatimonadetes, genus of Gemmatimonas (GenBank accession number is JX437625.1). Phylogenetic analysis showed that cyanobacterium Synechococcus sp. 1Dp66E-1 forms the unique branch and belongs to a cluster of Synechococcus, including freshwater and sea strains. Oscillatoriales cyanobacterium 2Dp86E belongs to a cluster of Leptolyngbya strains. Isolate Nostoc sp. 10Dp66E forms unique branch and belongs to a cluster of the genus Nostoc, with the closest relative of Nostoc commune isolates.

Hydrogen peroxide inhibits photosynthetic electron transport in cells of cyanobacteria.

The effect of H2O2 on photosynthetic O2 evolution and photosynthetic electron transfer in cells of cyanobacteria Anabaena variabilis and Anacystis nidulans was studied. The following experiments were performed: 1) directly testing the effect of exogenous H2O2; 2) testing the effect of intracellular H2O2 generated with the use of methyl viologen (MV); 3) testing the effect of inhibiting intracellular H2O2 decomposition by salicylic acid (SA) and 3-amino-1,2,4-triazole (AT). H2O2 inhibited photosynthetic O2 evolution and light-induced reduction of p-benzoquinone (BQ) + ferricyanide (FeCy) in the Hill reaction. The I50 value for H2O2 was ~0.75 mM. Photosynthetic electron transfer in the cells treated with H2O2 was not maintained by H2O2, NH2OH, 1,5-diphenylcarbazide, tetraphenylboron, or butylated hydroxytoluene added as artificial electron donors for Photosystem (PS) II. The H2O --> CO2, H2O --> MV (involving PSII and PSI) and H2O --> BQ + FeCy (chiefly dependent on PSII) electron transfer reactions were inhibited upon incubation of the cells with MV, SA, or AT. The N,N,N,N-tetramethyl-p-phenylenediamine --> MV (chiefly dependent on PSI) electron transfer was inhibited by SA and AT but was resistant to MV. The results show that H2O2 inhibits photosynthetic electron transfer. It is unlikely that H2O2 could be a physiological electron donor in oxygenic photosynthesis.

Lag phase of CO2-dependent O2 evolution by illuminated Anabaena variabilis cells.

The steady-state rate of CO2-dependent O2 evolution by Anabaena variabilis cells in response to illumination was established after a lag phase. The lag phase was shortened (1) in cells incubated with glucose as an oxidizable substrate and (2) upon an increase in light intensity. The lag phase was absent during electron transfer from H2O to p-benzoquinone (in combination with ferricyanide) involving Photosystem II. A lag was observed during electron transfer from H2O to methyl viologen involving Photosystems II and I, but not for electron transfer from N,N,N',N'-tetramethyl-p-phenylenediamine (in combination with ascorbate) to methyl viologen involving only Photosystem I. The lag phases of the light-induced H2O --> CO2 and H2O --> methyl viologen electron transfer reactions showed the same temperature dependences at 10-30 degrees C. The lag was prevented by 3-(3,4-dichlorophenyl)-1,1-dimethylurea at concentrations that caused partial inhibition of photosynthetic O2 evolution. Retardation of cell respiration by a combination of CN- and benzylhydroxamate shortened the lag phase of the H2O --> methyl viologen electron transfer. It is concluded that the lag phase is associated with the electron transfer step between Photosystem II and Photosystem I common for the photosynthetic and respiratory chains and is due to the stimulation of cell respiration during the initial period of illumination as a consequence of an increase in the reduced plastoquinone pool and to subsequent retardation of respiration resulting from the transition of the electron transfer chain to the competitive pathway involving Photosystem I.

Hydrogen peroxide inhibits the growth of cyanobacteria.

H2O2 at concentrations of 10(-5)-10(-4) M suppresses phototrophic growth of Anacystis nidulans and Anabaena variabilis in dialysis culture. The growth of the cyanobacteria resumed after a long adaptation period. In batch cultures, the growth of A. nidulans and A. variabilis was suppressed after one-time addition of 10(-2)and 10(-3)-10(-2) M H2O2, respectively. Inducing intracellular H2O2 formation by adding methylviologen, vitamin K3, or phenazine methosulfate suppresses the growth of both cyanobacteria. The catalase inhibitor salicylic acid suppresses the growth of A. nidulans and A. variabilis at a concentration of 5.10(-3) M. The data suggest an inhibitory effect of H2O2 on the growth of the cyanobacteria. H2O2 is unlikely to serve as an electron donor during photosynthesis.

[Intolerance to cow's milk]. / K voprosu o neperenosimosti korov'ego moloka

The authors report results of allergological history, of passive haemagglutination reaction, lymphocytes blast transformation and leucocytes migration inhibition tests in 100 patients suffering from affections involving the gastro-intestinal tract. Control investigations were carried out in 20 practically healthy individuals. From these results the authors conclude that the data of the allergological history and clinical symptoms of the cow milk intolerance are determined, above all, by the immuno-allergic mechanisms, this being confirmed by the results of the "in vitro" methods characterizing the humoral and cellular types of the immunological reactivity.