An expression of calpain and caspase-1 as well as the concomitant ultrastructural alterations were investigated during necrosis of the mouse Ehrlich ascites carcinoma. The calpain expression was registered at 0 h and 1 h although caspase-1 did not induce any signals during these time periods. The rise of the cytoplasmic lytic zones contacted by calpain antibodies was identified as a morphologic event corresponding to the expression of calpain. Lytic zone's distribution followed by the appearance of the calpain/caspase-1 clusters assigned for lysis of the Golgi vesicles and ER. Also, the microapocrine secretion of the vesicles containing the calpain/caspase-1 clusters was detected. Further, the lysis of the plasma membrane occurred due to progression of intracellular lysis. Rupture of the plasma membrane resulted in the termination of secretion and dissemination of cell contents. The nuclei still had their normal shape. Nuclear lysis continued to rise with intranuclear lytic zones, of which the progression was accompanied with the presence of calpain/caspase-1 clusters. The data contribute to the concept of the initial role of calpain for tumor cell destruction, provide first evidence of the calpain/caspase-1 pathway in tumor cells, and highlight microapocrine secretion as a possible tumor cell death signalling mechanism.

It was shown that tobacco leaf treatment with 100 mM H2O2 increased their content of endogenous H2O2 and activities of catalase and hydrolases (acid phosphatase, proteases, and RNase) and also caused various changes in the cell structure. In this case, programmed cell death (PCD) occurred in some cells, which was observed as chromatin condensation, cytoplasm collapse, etc. In the meantime, many cells displayed organelle activation rather than PCD. It is suggested that cells that undergo H2O2-dependent PCD release signaling molecules inducing protective mechanisms against oxidative stress in neighboring cells not exhibiting PCD.

It was shown that tobacco leaf treatment with 100 mM H₂0₂ increased their content ofendogenous H₂0₂ and activities of catalase and hydrolases (acid phosphatase, proteases, and RNase) and also caused'various chang- es in the cell structure. In this case, programmed cell death (PCD) occurred in some cells, which was ob- served as chromatin condensation, cytoplasm collapse, etc. In the meantime, many cells displayed organelle activation rather than PCD. It is suggested that cells that undergo H₂0₂-dependent PCD release signaling molecules inducing protective mechanisms against oxidative stress in neighboring cells not exhibiting PCD.

The present work reveals the effect of kappa-, lambda- and kappa/beta-carrageenans on the immune modulation and supramolecular structure of lipopolysaccharide (LPS). The kappa/beta carrageenan was able to increase the synthesis of anti-inflammatory interleukin-10 (IL-10) in vitro, and at low concentrations, their activity in the mixture with LPS was higher than that of LPS alone. Kappa-carrageenan significantly inhibited LPS-induced upregulation of reactive oxygen species (ROS). The activation of cells by kappa-carrageenan occurs through TLR4 receptor specific for LPS. Carrageenans reduced (kappa-) or completely inhibited (lambda-) collagen-induced platelet aggregation and decreased their aggregation activity caused by cooperative effect of LPS and collagen. The transformation of ultrastructure of LPS by action of kappa- and kappa/beta-carrageenans is observed. Moreover, carrageenans changed both the sizes and ζ- potentials of the LPS.

It is shown that κ/ß-carrageenan obtained from red marine alga Tichocarpus crinitus possesses antiviral activity against Tobacco mosaic virus (TMV). Two days after inoculation of Nicotiana tabacum L. cv. ‘Samsun’ detached leaves with a mixture of TMV (1 μ/ml) and carrageenan (1 mg/ml), the infectivity and virus content in the leaves as well as the intracellular accumulation of virus particles were significantly inhibited in comparison with leaves inoculated with TMV only. The carrageenan applied 24 h prior to inoculation with TMV also exhibited the antiviral effects but to a lower degree than when the virus and polysaccharide were inoculated together. As the infection developed, the inhibitory effects of carrageenan decreased. Treatment of the leaves with carrageenan affected the formation of TMV-specific intracellular inclusions (granular and tubule) known to consist of the virus-encoded protein components of the viral replicase. A characteristic of the infection development in the presence of carrageenan, 4 days after infection of the leaves with TMV, was the predominant formation in cells of granular inclusions famous to appear at early stages of TMV multiplication. At the same time, cells of the leaves inoculated with TMV alone contained for the most part tubule inclusions considered to arise from granular ones on the advanced infection stages. Taken together, our observations indicate that the κ/ß-carrageenan inhibits TMV infection in detached tobacco leaves at early stages.

Formation of germinal granules during oogenesis was studied in sea cucumbers, Apostichopus japonicus, Selenka, 1867, using transmission electron microscopy. It was found that within the early oogenesis mitochondria interact with a Balbiani body, gradually become immersed into its substance and transformed into electron-dense structures, which are similar to the germinal granules of metazoans. In late oogenesis, formed germinal granules lose their contacts with a Balbiani body and are localized in the cortical portion of the oocyte, near the cell membrane. Vestigial mitochondrial cristae are a typical feature of germinal granules. The obtained data suggest that the process of transformation of mitochondria into germinal granules is one of the functions of the Balbiani body, whose role still remains unexplained.

The effect of chitosan on the development of infection caused by Tobacco mosaic virus (TMV) in leaves of Nicotiana tabacum L. cv. Samsun has been studied. It was shown that the infectivity and viral coat protein content in leaves inoculated with a mixture of TMV (2 μg/mL) and chitosan (1 mg/mL) were lower in the early period of infection (3 days after inoculation), by 63% and 66% respectively, than in leaves inoculated with TMV only. Treatment of leaves with chitosan 24 h before inoculation with TMV also caused the antiviral effects, but these were less apparent than when the virus and polysaccharide were applied simultaneously. The inhibitory effects of the agent decreased as the infection progressed. Inoculation of leaves with TMV together with chitosan considerably enhanced the activity of hydrolases (proteases, RNases) in the leaves, in comparison with leaves inoculated with TMV alone. Electron microscope assays of phosphotungstic acid (PTA)-stained suspensions from infected tobacco leaves showed that, in addition to the normal TMV particles (18 nm in diameter, 300 nm long), these suspensions contained abnormal (swollen, "thin" and "short") virions. The highest number of abnormal virions was found in suspensions from leaves inoculated with a mixture of TMV and chitosan. Immuno-electron microscopy showed that "thin" virus particles, in contrast to the particles of normal diameter, lost the ability to bind to specific antiserum. It seems that the chitosan-induced activation of hydrolases stimulates the intracellular degradation of TMV particles and hence hydrolase activation may be considered to be one of the polysaccharide-mediated cellular defense mechanisms that limit virus accumulation in cells.

The effect of 20 cyclopentane β,β′-triketones and their sodium salts on the development of infections caused by tobacco mosaic virus (TMV) in leaves of tobacco (Nicotiana tabacum L. cv. Xanthi-nc) has been studied. It has been shown that the strongest antiviral effect is produced by sodium salts of 2-acetyl-4,7-dithio-2,3,4,5,6,7-hexahydro-1H-inden-1,3-dione, 2-acetyl-4-oxa-7-thio-2,3,4,5,6,7-hexahydro-1H-inden-1,3-dione, and 2-acetyl-4,5-didodecylthiocyclopent-4-en-1,3-dione. These compounds at a concentration of 2 mg/mL decrease the number of local TMV-induced necroses formed on inoculated tobacco leaves by 98% and have no toxic effect on leaf tissues.

Modern ideas on the biogenesis of plant peroxisomes, their involvement in the production and detoxification of reactive oxygen species, and the role in the processes they mediate are discussed. The data on the proliferation and degradation of these organelles in the cell during the oxidative stress and on their involvement in the generation of signaling molecules are considered.

The physicochemical properties and morphology of κ, κ/β, κ/ι, and λ-carrageenans from red algae of the families Gigartinaceae and Tichocarpaceae were analyzed and compared. The highest molecular weights (527 kDa) and negative electrokinetic potentials (–36.4 mV) were obtained for x -carrageenan, which had the conformation of a disordered coil whereas fine threads of κ and κ/β-carrageenans formed long fibrils of width up to 16 nm that were more heterogeneous in the latter instance whereas κ/ι-carrageenan formed a fibrous network structure.

The activity of hydrolases (protease, RNase) in uninfected and tobacco mosaic virus-infected tobacco leaves of the Samsun variety, untreated and treated with disodium salt of 2-acetyl-4-hydroxycarbonyl-methylthio-5-chlorocyclopent-4-en-1,3-dione (DS), was determined. It was shown that treatment of leaves with this compound significantly increased the activity of hydrolases in them compared to untreated leaves. In infected leaves treated with DS one day before infection, along with an increased level of hydrolases, one revealed more viral particles exposed to destructive changes in infected, rather than untreated, leaves. It is assumed that the DS-caused activation of hydrolases promotes the destruction of viral particles and is therefore one of the cell defense mechanisms induced by this compound that prevents the intracellular accumulation of virus.

In young systemically infected leaves of Datura stramonium L., a severe strain of Potato virus X (PVX) accumulated to a lower degree than a mild strain. Infected leaves had increased protease and RNase activities in comparison with those of healthy controls. The highest hydrolase activities were found in leaves infected with the severe strain. Negative-staining electron microscopy of dips from the infected leaves indicated that PVX virions underwent destructive changes, which resulted in the appearance of abnormal (swollen and thin') particles. Immuno-electron microscopic assays showed that thin PVX particles, in contrast to those of normal diameter, lost the ability to bind with specific antiserum. The relative number of thin virions in leaves infected with the severe PVX strain was considerably higher than in leaves infected with the mild strain. This shows that a correlation exists between increased protease activity and intracellular destruction of virions. In abnormal virions, the viral RNA appears to be available for RNase attack. Therefore, it seems that high RNase activity together with increased generation of abnormal virions in the leaves infected with the severe strain promote inactivation of the viral RNA with RNase. We suppose that the enhanced hydrolase activities in the leaves infected with severe PVX strain, on the one hand, limit viral accumulation and thus play a defensive role and, on the other hand, cause considerable intracellular pathological changes resulting in severe symptoms.