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Accumulation of considerable amounts of viral particles has been demonstrated in parenchymal cells of young leaves in tobacco cultivar Samsun systemically infected with any of studied tobacco mosaic virus (TMV) strains isolated from pepper (TMV-p), tomato (TMV-t), and eggplant (TMV-e). Abnormal (swollen and thin) virions were found, which points to their destruction. Cell infection with all studied strains was accompanied by the activation of the lysosomal compartment manifested as formation of nascent dictyosomes, elements of smooth endoplasmic reticulum, cytoplasmic vacuoles, various vesicles, invaginated mitochondria, and multivesicular bodies. The studied viral strains could be arranged in the following sequence according to the degree of lysosomal compartment stimulation and induction of intracellular lytic processes mediating the destruction of viral particles and cell structures: TMV-p > TMV-e > TMV-t.

The effect of fucoidan from the brown alga Fucus evanescens on the spread of infection induced by tobacco mosaic virus (TMV) was investigated in the leaves of tobacco (Nicotiana tabacum L.) of two cultivars (Ksanti-nk and Samsun). In the leaves of cv. Ksanti-nk inoculated with a mixture of TMV preparation (2 μg/ml) and fucoidan (1 mg/ml), the number of local necrotic lesions induced by the virus decreased by more than 90% as compared with the leaves inoculated with the virus alone. In tobacco leaves of cv. Samsun, virulence and the concentration of the virus 3 days after inoculation with the same mixture of TMV and fucoidan were by 62 and 66%, respectively, lower than in the leaves inoculated with TMV alone. As the infection spread, the inhibitory effect of fucoidan decreased. When the leaves were treated with fucoidan before and after the inoculation with TMV, its antiviral activity was less pronounced than when a mixture of the virus and the polysaccharide was used as inoculum. Electron microscopic investigation of TMV mixed with fucoidan often showed agglutinated virions. The highest virulence of the mixture (TMV preparation, 12 μg/ml, plus fucoidan, 1 mg/ml) was observed upon its twofold dilution, and after that it decreased. It was concluded that, when the leaves were inoculated with the mixture of TMV and fucoidan, the latter affected not only the plant but the virus as well. Treatment of tobacco leaves, cv. Ksanti-nk, with actinomycin D (10 μg/ml) 24 h before the inoculation with TMV almost completely suppressed the effect of fucoidan, indicating that fucoidan acted at a gene level.

SummaryTo highlight the ultrastructural features of transformation occurring with germplasm-related structures (GPRS), the spermatogenic cells of Xenopus laevis were studied by transmission electron microscopy and quantitative analysis. It was determined that in spermatogonia and spermatocytes, the compact germinal granules underwent fragmentation into particles comparable with inter-mitochondrial cement (IMC). Fragments of IMC agglutinated some cell mitochondria and resulted in the creation of mitochondrial clusters. Clustered mitochondria responded with loss of their membranes that occurred by the twisting of membranous protrusions around themselves until multi-layered membranes were formed. The mitochondrial affinity of multi-layered membranes was proven by an immunopositive test for mitochondrial dihydrolipoamide acetyltransferase. As a consequence of mitochondrial membrane twisting, the naked mitochondrial cores appeared and presumably underwent dispersion, which is the terminal stage of GPRS transformation. As no GPRS were observed in spermatids and sperm, it was assumed that these structures are functionally assigned to early stages of meiotic differentiation.

Difficulties in characterization of spermatozoa of the Metazoa are now related to insufficiency of the traditional terms “primitive spermatozoon,” “modified spermatozoon,” and “aberrant spermatozoon” introduced by G. Retzius and A. Franzen for description of intermediate forms discovered in the 20th century. In this respect, some authors propose to reject the Retzius' and Franzen's terms and turn to the terminological system of G. Rouse and B. Jamieson, the terms of which (“ectaquaspermatosoa,” “entaquaspermatozoa,” and “introspermatozoa”) determine specific features of insemination, but do not reflect the structure of spermatozoa. The assertion of “helplessness” of the traditional structural Retzius' and Franzen's terms is unfounded. Their preservation is desirable if one wishes to preserve the comparative-morphological approach to the characterization of male gametes of the Metazoa. The terms “primitive spermatozoon,” “modified spermatozoon,” and “aberrant spermatozoon” will become more universal if the method of their combined utilization is applied.

The ultrastructural mechanism of postspawning sperm resorption in the testes of the sea urchin Strongylocentrotus nudus is described. Two types of phagosomes (containing sperm and containing residual bodies) are formed in the cytoplasm of nutritive phagocytes. The phagosomes fuse with electron-dense globules, and their contents are gradually destroyed. Afterward, phagosomes are transformed into electron-transparent vacuoles, which are finally compressed by the surrounding cytoplasm.

The process of the destruction of nonreleased spermatozoa was studied using TEM in the postspawning gonads of the chum salmon Oncorhynchus keta and the pointhead flounder Cleisthenes herzensteini, as representatives of monocyclic and polycyclic fishes respectively. It was shown that in both species residual sperm cells are destroyed through fragmentation of chromatin and the entire cell. It is supposed that the process of destruction in this case is connected with autolytic disintegration known in some multicellular animals, but never described for Teleostei.

The process of resorption of spermatozoa is described in the testes of the starfish Asterina pectinifera. It is shown that the mode of resorption of the male gametes in this species is different from that in the starfish Asterias vulgaris (see Walker [17, 18]), A. amurensis, and Aphelasterias japonica (see Kas’yanov et al.

Summary The interaction between chromatoid bodies and mitochondria in neoblasts of the asexually reproducing planarian Girardia (Dugesia) tigrina, as well as in oogonial cells of the spontaneously sexualized individual G. tigrina, was studied using transmission electron microscopy. Mitochondria-chromatoid body complexes (chromatoid bodies surrounded by several mitochondria) are typical of planarian neoblasts and oogonia. In many mitochondria contacting the chromatoid bodies in gonial cells, the outer mitochondrial membrane disappeared, and release of the mitochondrial matrix was observed. The mitochondial derivatives devoid of an outer membrane and initially containing cristae of the inner mitochondrial membrane apparently were integrated with the material of chromatoid bodies. These findings agree with our previous ultrastructural data on sea urchin, fish and holothurian gonial cells and also with the molecular evidence provided by other authors for the presence of mitochondrial ribosomal RNA in germline...

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.

It was found that in the Graafian oocytes of laboratory mice Mus musculus the population of electron-dense bodies contains two patterns of structures. One of these, designated as cortical granules, originated from the Golgi complex and was surrounded by a membrane. The other was discovered as cristae-containing mitochondrial derivatives lacked an outer membrane. It was found that the mitochondrial derivatives underwent progressive condensation and transformed into electron-dense bodies similar to germinal bodies of metazoan animals. Based on examination of Graafian follicle oocytes from 5 female individuals, about 15% of electron-dense bodies were cortical granules. However, about 85% of electron-dense bodies were condensing mitochondrial derivatives transforming into electron-dense bodies.

The ultrastructural mechanisms of waste-sperm phagocytosis and postspawning shrinkage were studied for accessory cells (nutritive phagocytes; NPs) of the sea urchin Anthocidaris crassispina. Sperm cells were phagocytosed by NPs; they penetrated into the cytoplasm of the NPs inside heterophagosomes formed by an invagination of the cell membrane. Single-sperm-containing heterophagosomes aggregated to form large multisperm heterophagosomes that were accompanied by cytoplasmic vesicles and lipids. Two types of vesicle, viz., Golgi-complex-derived electron-dense vesicles ("zymogen granules") and smooth-endoplasmic-reticulum-derived electron-lucent vesicles, were incorporated within multisperm heterophagosomes. Completed multisperm heterophagosomes were transformed into electron-dense remnant bodies, the content of which underwent destruction, resulting in "empty" vacuoles inside the remnant body. The "empty" vacuoles were then compressed by the surrounding cytoplasm. Shrinkage of NPs occurred upon completion of sperm degeneration in gonad tubules. This process was undertaken by structures termed cell-size-reducing autolysosomes, which performed two types of autolysis, and resulted in the formation of "cheese-hole"-like vacuoles in the cytoplasm of NPs. Subsequent cytoplasmic compression of these vacuoles was required for the reduction in size of NPs, an essential event for remodeling the cell for the next gametogenetic cycle.

Certain physicochemical properties of glycoglycerolipids from marine alga Laminaria japonica (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol) and their ability to be incorporated into immunostimulating complexes (ISCOMs) used for delivery of microbial and tumor antigens in vesicular form were comparatively described. These glycolipids proved to considerably differ by fatty acid composition, degree of unsaturation, and phase transition temperatures. Production of modified ISCOMs through incorporation of these glycolipids into the vesicle instead of the glycolipid component was demonstrated. Preliminary data demonstrated no significant increase in immune response to Yersinia pseudotuberculosis porin in the modified (with monogalactosyldiacylglycerol) and classical (with phosphatidylcholine) ISCOMs as compared to pure porin.

Some physicochemical properties of glycoglycerolipids (monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol) from the sea algae Laminaria japonica, as well as their ability to become incorporate into immunostimulating complexes (ISCOMs), used as a delivery system of microbial and tumor antigens in vesicular form, were studied. These glycolipids were found to differ essentially in fatty acid composition, unsaturation index and thermotropic behavior. The possibility of ISCOM modification by embedding the glycolipids studied instead of a phospholipid component in vesicles was shown. A preliminary research of the immunogenicity of the pore-forming protein from Yersinia pseudotuberculosis in modified (by monogalactosyldiacylglycerol) and typical (egg phosphatidylcholine) ISCOMs did not reveal a significant enhancement of immune response in comparison with that of isolated protein.

The process of sperm development in Phoronopsis harmeri was studied by electron microscopy. Developing spermatogenical cells are aggregated around the capillaries of the haemal plexus. The spermatogonia, which are situated around the capillary walls of the caeca, are remarkable for the presence of germ-line vesicles and contain their centrioles near the cell membrane. The spermatocytes and spermatids are flagellated cells arranged in clusters. During spermiogenesis the basal body/flagellum complex migrates to the apical pole of the spermatid. The acrosome-like structure arises from material produced by the Golgi complex. It lacks a surrounding membrane and has a fibrillar content. The nucleus elongates and the condensation of chromatin is caused by an activation of 'initiation centres'. The late spermatid and the spermatozoon appear as two-armed 'V'-shaped cells in which one arm contains the nucleus and posteriorly located mitochondria, and the other one is the axoneme. Spermatogenesis of P. harmeri is an interesting example of gamete differentiation where advanced sperm structure is combined with a plesiomorphic pattern of sperm development characterized as 'flagellate spermatogenesis'.

It is established that the central area of TMV-induced local lesions developed in detached Datura stramonium leaves, along with the completely collapsed cells (types I and II), contains cells (type III) conserving to a certain degree integrity of their structural components. A characteristic of the type III cells was the accumulation of considerable amount of virus and formation of TMV-specific granular and tubular inclusions. The study of lesion development showed that a proportion of the collapsed cells and cells of type III did not essentially change in the period up from 3 to 5 days after infection of the leaves. These data suggest that the disease development in cells of type III does not lead to a hypersensitive response and is very similar to that in the systemically infected cells.

Adult sea urchins, Anthocidaris crassispina, were exposed to 0.1 and 10 mgL(-1) phenol for 4 weeks. Abnormal sperm development was clearly evident in phenol-treated sea urchins, although no mortality was found throughout the exposure period. Occurrences of multinucleate sperm cells (including spermatocytes to spermatozoa) showed a significant increase from 0.07% in the control to 10.7% and 43.3% in the 0.1- and 10-mgL(-1) treatments, respectively (P

The development of male gametes (spermacia) in the red alga Gracilaria verrucosa has been studied using methods of transmission electron microscopy. Early spermatangia located along the wall of the conceptacle show an elongated shape in the thin sections. In the central part of the electron-dense cytoplasm of these cells there is a nucleus; numerous fibrous vesicles are arranged in the periphery. During the process of differentiation, the spermatangia become more rounded in shape and a large spermatangial vesicle is developed. The subsequent development of spermatium is accompanied by polarization of the spermatangium and the subsequent excretion of the spermatangial vesicle. The spermatia are oval cells containing a nucleus and fibrous vesicles. The process of differentiation of male gametes in G. verrucosa does not differ from that in five species of the genus Gracilaria, where it has already been studied. However, any conclusions about the degree of similarity between the spermatia in all the studied species can be made only after a detailed comparative analysis of the ultrastructural characteristics of these gametes.

When tobacco mosaic virus (TMV) and potato virus X (PVX) pre­pa­ra­tions were mixed with the sap from the halo zone (HZ) tissues surround­ing homologous virus-induced local lesions in Datura stramonium and Gomphrena globosa leaves, respectively, and the mixtures were incubated for 18 h at 37 °C, the virus particles underwent destruction. Under the electron microscope abnormal (swollen and “thin”) virions were observed in the incubated virus preparations negatively stained with phospho­tung­stic acid. Sometimes the TMV particles were “cut” across into fragments. Treatment of the virus preparations with the sap from the healthy leaves or HZ surrounding heterologous virus-induced local lesions may cause certain destructive changes of virus particles but to a far lesser extent than treatment with the sap from the homologous virus-induced HZ. Possible mechanisms of destruction of the virus particles are discussed.

Background:Injury to the mesothelial layer of the peritoneal membrane during peritoneal dialysis (PD) is implicated in loss of ultrafiltration capacity, but there are no validated biomarkers for me...

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.

Summary The phenomenon of “flagellate spermatogenesis” typically known among marine invertebrates with “primitive” sperm and external or external-internal fertilization is discussed. It is suggested that “flagella bearing” in early germinative cells might be explained by plesiomorphic similarity between these cells and flagellate somatic epithelial cells. The early germ cells of more apomorphic multicellular animals using internal fertilization with “modified” and “aberrant” sperm typically have no flagella and this organelle, as the sperm tail, first appears in spermatids. It is speculated that the “flagellate” pattern typifies the basal level and that the transition between “flagellate” and “specialized” spermatogenesis constitutes a significant step in evolution.

Literature data on the structure and origin of material of the germ cell line determinants and on the presence of products of nuclear and mitochondrial genomes in the structured germ determinants (nuage) are reviewed. The personal data, obtained on spermatogenic cells of sea urchin and of other marine invertebrates, evidence the transformation of the mitochondrial matrix into the nuage material. The presence of matrix structures of mitochondrial origin in the germ plasm, which ensure reproduction and the function of the structured macromolecular complex of germ determinants relatively independent from the nuclear genome, is suggested.

132 The bivalve mollusk Mactra chinensis Philippi, 1847 is of significant commercial importance in the Asian–Pacific area; therefore, it is studied by malacol� ogists intensely. On the basis of morphological data, researchers suggested a divergence of this species in the Sea of Japan. As a consequence of the divergence, the southern and northern populations have already appeared which are different in the shape, color, and the shell pattern. For example, in the South Korean part of the Sea of Japan, the Mactra shell is described as faintly colored, yellowish, without any brown rays, while in the Russian part of the Sea of Japan, there is

Summary During spermiogenesis in the sea urchins Diadema setosum and Salmacis bicolor, two pattems of flagellum development were shown. For both species a significant proportion of spermatids examined possessed an axoneme that remained associated with the nucleus during development, and this results in the formation of sperm cells with an anteriorly directed flagellum, whereas the majority of spermatids gave rise to sperm cells with a posterior flagellum which is typical of multicellular animals. The morphology of D. setosum and S. bicolor sperm cells was generally similar to that of other echinoids.

The process of sperm development in the sea urchin Anthocidaris crassispina was studied by light and electron microscopy. Similar to other echinoids studied, a single flagellum, striated rootlet and nuage-like materials were present in spermatogonia of A. crassispina. Spermatocytes near the diplotene stage showed intracellular localization of the axoneme which appeared to be a retracted flagellum prior to cell division. Fibrous filaments were associated with a proximal centriole in spermatocytes and spermatids and might be involved in movement of the proximal centriole. An acrosomal vesicle was developed and a residual body was formed in spermatids. The special development patterns in A. crassispina attributed to the presence of two patterns of tail development and two patterns of mitochondrial development during spermiogenesis. These four lines of spermiogenesis resulted in the formation of four morphological types of sperm cell, i.e. sperms with: (1) a symmetrical midpiece and posterior tail, (2) an asymmetrical midpiece and posterior tail, (3) a symmetrical midpiece and bent tail and (4) an asymmetrical midpiece and bent tail. Sperm cells with bent tails (type 3+4) were probably still at the late spermatid stage because results of scanning electron microscopy demonstrated gradual detachment and eventual straightening of the bent tail, and their percentage occurrence in the sperm population decreased significantly (P

Spermatogenesis and sperm structure of the nemertine wormProcephalothrix sp. were studied by transmission electron microscopy. It is shown that a flagellum and proacrosomal vesicles are common in spermatogonia and spermatocytes as in spermatogenesis of a number of marine invertebrates with external fertilization. Originally, the animals were collected asProcephalothrix spiralis but they were found to have a type of spermatozoon different from that ofP. spiralis as described by Turbeville & Ruppert (1985). The re-identification of the material collected in the Japan Sea has shown that the features are characteristic, ofP. spiralis (Coe, 1930). This finding suggests thatP. spiralis shows variations in different parts of the world.

Accessory cells were studied in early spermatogenesis of flatfishes Glyptocephalus stelleri and Pleuronectes pinnifasciatus using transmission electron microscopy. The morphological organization of accessory cells in G. stelleri was similar to that of Sertoli cells. In P. pinnifasciatus, these cells had morphological organization, which had not been previously described.

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.

Effect of chitosan on the mesophyll cell ultrastucture and activity of hydrolases in leaves of tobacco cv. Samsun was studied. It was shown that, in many cells, chitosan treatment stimulated the protein-synthesizing apparatus (nucleolus dimension and amount of both mitochondria and rough endoplasmic reticulum membranes increased) and, at the same time, caused some activation of lytic compartment expressed in the stimulation of the formation of dictyosomes, smooth ER elements and cytoplasmic vacuoles, which are all prominent constituents of this compartment. In biochemical experiments, it was established that chitosan substantially enhanced activity of hydrolases (acid phosphatase, RNase, proteases) in the leaves as compared to untreated leaves. In some cells chitosan treatment caused considerable destructive changes (condensation of nuclear chromatin, collapse of cytoplasm and so on) that can be classified as a result of programmed cell death development.

The relationships between germinal bodies and mitochondria were studied in the holothurian Apostichopus japonicus and the flounder Pleuronectes asper using TEM. In the gonial cells of both species the mitochondria are arranged around germinal bodies and are in contact with the latter. A gradual disappearance of the outer membrane is found in the mitochondria that interact with the germinal substance. Later on, dispersion of the globules of the mitochondrial matrix containing mitochondrial cristae occurs. It is supposed that the substance of the mitochondrial matrix takes part in the development and functioning of the germinal plasm in both invertebrates and vertebrates.

Summary In the holothurian, Cucumaria japonica, deep invaginations of the germinal epithelium of the testis are formed during the period of active spermatogenesis (January-February) but are reduced in prespawning animals (August). The invaginations contain basal lamina which envelope the testis and separate the haemal sinus from the gonad lumen. They are lined with germinal epithelium. Nurse cells are not present within regions of the germinal epithelium associated with invaginations of the lamina. These regions are invested by spermatogenic cells only.

Summary The structure of the spermatozoon and spermatogenesis of Discinisca tenuis (Inarticulata) and Kraussina rubra (Articulata) are described by transmission electron microscopy. The spermatozoon of D. tenuis has a similar morphology to that of other inarticulate brachiopods. The head (about 1.9 μm long) is composed of a nucleus which is invaginated anteriorly and posteriorly, the anterior invagination partially housing the pyriform acrosome. The acrosome is differentiated internally and is separated from the nucleus by subacrosomal material. The mid-piece is composed of a ring of four or five spherical mitochondria which surround the proximal and distal centrioles which are arranged orthogonally. By contrast the spermatozoon of K. rubra has a head which is 2 μm long × 1.1 μm in diameter. The nucleus which is rounded anteriorly is capped by a small (0.5 μm diameter) disc-shaped acrosome. The mid-piece has a single ring-shaped mitochondrion which surrounds the centrioles which are almost in line with ea...

Influence of chitosan on the accumulation and state of tobacco mosaic virus (TMV) in the mesophyll cells of Nicotiana tabacum L. var Samsun leaves in early period of infection development (3 days after infection of leaves) has been studied. The virus accumulated in the cells of the leaves treated for 24 h before infection with chitosan to a lesser degree than in the control cells. The chitosan affected the formation of TMV-specific granular and tubular inclusions which are known to consist of the viral replicase components. Three days after infection of the leaves treated with the chitosan, a typical sign of the infection development was the predominant formation of granular inclusions which are known to appear at the early stages of TMV replication. The infected cells of the leaves untreated with chitosan contained mainly tubular inclusions which had been shown previously to be formed from granular ones at the last stages of the infection process. This indicates that chitosan treatment of the leaves leads to a delay of the development of infection. In phosphotungstic acid-stained suspensions obtained from the infected leaves, abnormal (swollen and "thin") TMV particles were observed along with normal ones. The appearance of abnormal virus particles seems to be caused by virus-induced activation of intracellular lytic processes. The most lytic activity in the infected cells as well as the highest number of abnormal viral particles was observed under the chitosan action. Therefore, it appears that chitosan-mediated stimulation of lytic processes causing destruction of TMV particles may be one of the protective mechanisms limiting virus accumulation in cells.

Ultrastructural examination of tobacco mosaic virus-induced local lesions developing in leaves of Datura stramonium plants demonstrated that, in the central area of the lesions, the cell response to viral invasion was not uniform. Most cells exhibited an acute hypersensitive reaction and underwent rapid and complete necrosis. However, some cells, despite considerable virus accumulation and immediate contact with completely collapsed cells, maintained a certain degree of structural integrity. Analysis performed showed that the proportion of collapsed and uncollapsed cells in the lesion centre 3 to 5 days after infection did not change essentially. These data suggest that the absence of hypersensitive response in some cells in the lesion centre is not due to an early stage of infection but is likely caused by cell tolerance of the virus.

Enzymatic (the action of lysozyme) and chemical (hydrogen peroxide) hydrolysis of chitosans with various degree ofacetylation (DA)--25, 17, and 1.5%--was performed. Purification and fractioning of the hydrolysis products were performed using dialysis, ultrafiltration, and gel-penetrating chromatography Low-molecular (LM) derivatives of the polysaccharide with molecular masses from 17 to 2 kDa were obtained. The study of their antiviral activity against the tobacco mosaic virus (TMV) showed that these samples inhibited the formation of local necroses induced by the virus for 50-90%. The antiviral activity of the LM chitosans significantly increased with the lowering of their polymerization degree. Furthermore, the products of the enzymatic hydrolysis possessed higher activity than the chitosan samples obtained as a result of chemical hydrolysis. It was revealed that the exhibition of the antiviral activity weakly depended on the degree of acetylation of the samples.

The effect of kappa/beta-carrageenan from red alda Tichocarpus crinitus on the development of a potato virus X (PVX) infection in the leaves of Datura stramonium L. has been studied. The treatment of leaves with carrageenan stimulates a protein synthesis in the cells, causing an increase in the size of nucleoli and in the number of mitochondria and membranes of the granular endoplasmic reticulum. At the same time, such treatment slightly stimulates lytic processes, causing an increase in the number of agranular endoplasmic reticulum cisterns, dictyosomes, and cytoplasmic vacuoles and the formation of cytoplasmic zones, transparent to electron microscopy. The carrageenan-induced stimulation of lytic processes results in the destruction of viral particles and can be considered as one of the defense mechanisms, preventing the intracellular accumulation of viruses. The carrageenan-stimulated formation of PVX-specific laminar structures, able to bind viral particles and, therefore, prevent their intracellular translocation and reproduction, represents another carrageenan-induced mechanism of the antiviral defense in plant cells.

The effect of disodium salt of 2-acetyl-4-hydroxycarbonylmethylthio-5-chlorocyclopent-4-en-1,3-dione on development of the infection caused by tobacco mosaic virus in the leaves of two Nicotiana tabacum L. cultivars--an oversensitive cultivar Xanthi-nc and systemically affected Samsun--was studied. The results suggest that this compound interferes with reproduction of the virus. This antiviral displayed the highest activity when applied in a mixture with the virus, presumably due to its action on both the plant and the virus.

Spermatogenesis in the silversides Oncorhynchus kisutch and cherry salmon O. masou, was investigated by transmission electron microscopy. It has been shown that male germ cells of both species had no difference in dimensional and ultrastructural parameters. The characteristic feature of spermatogonia was the presence of germ determinant substance, a cytoplasmic barker of sex line cells. Primary and secondary spermatocytes, as well as early spermatids were arranged in clusters consisted of synchronously developing cells. The spermiogenesis was peculiar in arising of electron-lucent vesicle which formed a structural complex with apical dense part of nuclear envelope. This complex has clear similarity with unformed spermatid acrosomes in many Metazoa and has been termed by the authors as an acrosome-like structure (AS). Disappearance of AS occurring at the final stage of the spermiogenesis allows considering AS as a temporary existing structure recapitulating the ancestral morphotype of salmonid sperm. Spermatozoa of both species are typical acrosome lacking cells which are characteristic of many representatives of Teleostei having external fertilization.

Influence of fucoidan from brown alga Fucus evanescens C. Ag. on the development of infection induced by potato virus X (PVX) in Datura stramonium leaves was studied. It as been shown that 24 h after the treatment of the leaves with fucoidan and following infection of them with PVX the accumulation of virus particles in infected cells during early infection period was substantially less than that in untreated control. Using ultrastructure-morphometric analysis, it has been established that fucoidan treatment increases at protein-synthesizing capability of cells (nucleolus dimension, amount of mitochondria and rough endoplasmic reticulum membranes become increased). At the same time, the fucoidan treatment causes some activation of lytic compartment which leads to destruction of virus particles and, therefore, might be considered as one of fucoidan-dependent protective mechanisms limiting virus accumulation in cells. Fucoidan stimulation of the formation of PVX-specific laminated structures capable of virus particles binding is possibly another induced antiviral cell mechanism, preventing from virus reproduction and transposition.

The influence of kappa/beta-carrageenan from red marine alga Tichocarpus crinitus on the development of tobacco mosaic virus (TMV) infection in Xanthi-nc tobacco leaves was studied. It was shown that the number of necrotic lesions on the leaves inoculated with the mixture of TMV (2 microg/ml) and carrageenan (1 mg/ml) was reduced by 87%, compared to the leaves inoculated with the virus only. The suppression of virus infection was also observed when leaves were treated with carrageenan 24 h before or 24 h after leaf inoculation with TMV; however, in these cases, suppression was less evident than after inoculation with the virus-polysaccharide mixture. It is supposed that the antiviral activity of carrageenan applied together with TMV may be explained by its action not only on the plant but also on the virus itself. The inhibitory effect of carrageenan pretreatment can be explained by its favorable effect on tissue resistance to infection. The suppression of this resistance by actinomycin D indicates that carrageenan functions via its action on the cell genome.

The influence of cyclopentane beta,beta'-triketones on the ultrastructure of root cap meristematic cells of Cucumis sativus L. under inhibition of root growth by these compounds was studied. It was shown that treatment of the seedlings by these substances at the concentration of 100 microg/ml caused, on the one hand, stimulation of protein-synthesizing apparatus (increase in the nucleolus size and in the number of mitochondria and rough endoplasmic reticulum membranes) and, on the other hand, stimulation of lytic processes. The fact that the used compounds, causing inhibition of the seedling growth, do not suppress but stimulate protein-synthesizing activity of the cells, according to existing concept, testifies to the compound-mediated induction of the cell resistance to unfavourable factors. Consequently, these compounds, in contrast with growth inhibitors suppressing cell metabolism completely, possess properties peculiar to retardants, growth inhibitors valuable for crop production.

The fragmentation of the biologically active 1,3;1,6-beta-D-glucan Antivir by endo-1,3-beta-D-glucanase LIV from crystalline styles of the marine mollusk Spisula sachalinensis was carried out. It was found that low molecular mass oligomers possessing a stabilizing effect on membranes and anti-viral activity against tobacco mosaic virus appeared in the process of enzymatic hydrolysis of Antivir. Biological activity of 1,3;1,6-beta-D-glucooligo- and polysaccharides was found to be associated with molecular mass (polymerization degree (n) not less than 14) and with presence of intralinked beta-1,6-connected monosaccharide residues. Probably, decrease in molecular mass is compensated by increase in number of intralinked beta-1,6-connected monosaccharide residues.

The yolk germinal granules in oocytes and embryonic cells of Apostichopus japonicus were studied by transmission electron microscopy. Analysis of the features of synthesis and utilization of yolk granules made it possible to reveal ultrastructural criteria to distinguish between granules of the forming and utilized yolk, and germinal granules. Based on these findings, the authors suppose that identification of germ plasm elements in oocytes and embryonic cells of A. japonicus is quite possible with ultrastructural analysis only, and does not require utilizing molecular markers.

A comparative study was made of the ultrastructure of parenchyma leaf cells of different soybean varieties systemically infected with soybean mosaic virus (SMV). It has been shown that virus accumulation and formation of virus-specific cylindrical inclusions (CIs) occur in the infected cells, in addition to intracellular changes showing stimulation of lytic processes, such as activation of smooth endoplasmic reticulum and Golgi apparatus, formation of cytoplasmic vacuoles, cytosegresomes, myelin-like bodies, different disturbances in the structure of cell organelles. Many infected cells demonstrated microbodies with invagination in which cylindrical inclusions were often found showing signs of destruction. It is suggested that such microbodies possess autophagic activity towards CIs. A possible relation of the observed virus-induced ultrastructural cell changes with the degree of SMV affection of investigated varieties is discussed

Difficulties in characterization of spermatozoa of the Metazoa are now related to insufficiency of the traditional terms "primitive spermatozoon", "modified spermatozoon", and "aberrant spermatozoon" introduced by G. Retzius and A. Franzen for description of intermediate forms discovered in the 20th century. In this respect, some authors propose to reject the Retzius' and Franzen's terms and turn to the terminological system of D. Rouse and B. Jamieson, the terms of which ("ectaquaspermatosoa", "entaquaspermatozoa", and "introspermatozoa") determine specific features of insemination, but do not reflect the structure of spermatozoa. The assertion of "helplessness" of the traditional structural Retzius' and Franzen's terms is unfounded. Their preservation is desirable if one wishes to preserve the comparative-morphological approach to the characterization of male gametes of the Metazoa. The terms "primitive spermatozoon", "modified spermatozoon", and "aberrant spermatozoon" will become more universal if the method of their combined utilization is applied.