The effect of pH on biological activity of plant cytotoxin cauloside C

The effect of plant carboxyl-containing glycoside cauloside C upon eucaryotic cells has been studied. The glycoside interacts with cells as a pH-dependent cytotoxin and increases K+ leakage and Ca2+ uptake with strong action in acidic media Cell viability after glycoside action at acidic pH may be recovered by the shift of medium pH from 5.6 to 7.4. Directed transport of low molecular weight effectors such as cAMP and Ca2+ to human embryo fibroblasts under the action of cauloside C has been demonstrated. Calcium uptake is accompanied by about a twofold stimulation of fibroblast proliferation in serum-free medium. The manifestation of the effect depends on the strictly determined time of the 'open' state of the membrane permeability (2 min) and upon concentration of glycoside in the medium (1 ng/ml) Cauloside C-stimulated Ca-transport is not blocked by Ca-channel blockers such as verapamil, diltiasem, and nitrendipine (all at a concentration of 1 x 10(-6) M) but these blockers inhibit cauloside C-stimulated proliferation of fibroblasts. We conclude that stimulation of fibroblast proliferation is caused by activation of membrane associated Ca-channels at the expense of calcium, incorporated into cells with cauloside C. The use of cauloside C as a new biochemical tool for cell permeabilisation is suggested.     

Structure of the nervous system in the tornaria larva of<Emphasis Type="Italic"> Balanoglossus proterogonius</Emphasis> (Hemichordata: Enteropneusta) and its phylogenetic implications

The tornaria larva of hemichordates occupies a central position in phylogenetic discussions on the relationships between Echinodermata, Hemichordata, and Chordata. Dipleurula-type larvae (tornaria and echinoderm larvae) are considered to be primary in the life cycle and thus provide a model for the ancestral animal common to all three taxa (the theory of W. Garstang). If the similarities between tornaria and the larvae in Echinodermata result from homology, their nervous systems should be basically similar as well. The present study utilizes anti-serotonin and FMRFamide antisera together with laser scanning microscopy, and transmission electron microscopy, to describe in detail the nervous system of the tornaria of Balanoglossus proterogonius. Serotonin immunoreactive neurons were found in the apical and esophageal ganglia, and in the stomach epithelium. FMRFamide immunoreactive neurons, probably sensory in nature, were detected in the apical ganglion and in the equatorial region of the stomach epithelium. At the ultrastructural level, the apical organ consists of a columnar epithelium of monociliated cells and includes a pair of symmetrical eyespots. The apical ganglion is located at its base and has a well-developed neuropil. Different types of neurons are described in the apical organ, esophagus, and stomach. Comparison with larvae in Echinodermata shows several significant differences in the way the larval nervous system is organized. This calls into question the homology between tornariae and echinoderm larvae. The possibility of convergence between the two larval types is discussed.     

Differential susceptibility to oxidative stress of two scleractinian corals: antioxidant functioning of mycosporine-glycine

This study examined the importance of mycosporine-glycine (Myc-Gly) as a functional antioxidant in the thermal-stress susceptibility of two scleractinian corals, Platygyra ryukyuensis and Stylophora pistillata. Photochemical efficiency of PSII (F_v/F_m), activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), and composition and abundance of mycosporine-like amino acids (MAAs) in the coral tissue and in symbiotic zooxanthellae were analyzed during 12-h exposure to high temperature (33 °C). After 6- and 12-h exposures at 33 °C, S. pistillata showed a significantly more pronounced decline in F_v/F_m compared to P. ryukyuensis. A 6-h exposure at 33 °C induced a significant increase in the activities of SOD and CAT in both host and zooxanthellae components of S. pistillata while in P. ryukyuensis a significant increase was observed only in the CAT activity of zooxanthellae. After 12-h exposure, the SOD activity of P. ryukyuensis was unaffected in the coral tissue but slightly increased in zooxanthellae, whereas the CAT activity in the coral tissue showed a 2.5-fold increase. The total activity of antioxidant enzymes was significantly higher in S. pistillata than in P. ryukyuensis, suggesting that P. ryukyuensis is less sensitive to oxidative stress than S. pistillata. This differential susceptibility of the corals is consistent with a 20-fold higher initial concentration of Myc-Gly in P. ryukyuensis compared to S. pistillata. In the coral tissue and zooxanthellae of both species investigated, the first 6 h of exposure to thermal stress induced a pronounced reduction in the abundance of Myc-Gly but not in other MAAs. When exposure was prolonged to 12 h, the Myc-Gly pool continued to decrease in P. ryukyuensis and was completely depleted in S. pistillata. The delay in the onset of oxidative stress in P. ryukyuensis and the dramatic increase in the activities of the antioxidant enzymes in S. pistillata, which contains low concentrations of Myc-Gly suggest that Myc-Gly provides rapid protection against oxidative stress before the antioxidant enzymes are induced. These findings strongly suggest that Myc-Gly is functioning as a biological antioxidant in the coral tissue and zooxanthellae and demonstrate its importance in the survival of reef-building corals under thermal stress.     

Selective resorption in nutritive phagocytes of the sea urchin Anthocidaris crassispina

Phagocytic resorption during spermatogenesis was studied in the sea urchin Anthocidaris crassispina. Nutritive phagocytes in gonad absorbed both waste sperm cells and residual bodies discarded from maturing spermatids, and these materials were subsequently compartmented in heterophagosomes. Based on 180 heterophagosomes examined by transmission electron microscopy, over 99% of heterophagosomes contained either residual bodies or sperm cells only. Simultaneous resorption of sperm cells and residual bodies in a heterophagosome was uncommon, with only approximately 0.56% occurrence, suggesting that heterophagosomes have a selective resorption ability in nutritive phagocytes.     

Effective Size of Subpopulations in Early-Run Sockeye Salmon Oncorhynchus nerkafrom Azabach'e Lake (Kamchatka): The Effect of Density on Variance of Reproductive Success

Using Parensky's approach for estimating the number of breeding pairs, we determined effective subpopulation size N _e in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka) in 1977 through 1981. On average (over years and populations), biased sex ratio decreased N _e by 7% as compared to the number of fish on the spawning sites (N _i). High density reduced the N _e/N _i ratio by 62–66% because some fish were excluded from spawning. Dominance polygyny as compared to monogamy and random union of gametes could reduce N _e by about 17%.     

Subsurface Musculature of Spiny-Headed Worms (Acanthocephala) and Its Role in Formation of Intercellular Matrix

Published and original data on the organization and ultrastructure of the subsurface (cutaneous) musculature, basal plate, and intercellular matrix of acanthocephalans (spiny-headed worms) were analyzed and reviewed. Similar to flatworms, the basal plate and the intercellular matrix of acanthocephalans proved to be derived from the cutaneous musculature. Specific structure of acanthocephalan cutaneous muscles (the lacunar system, nuclear secretion, specific block arrangement of myofilaments, etc.) allows us to consider it as a special kind of smooth muscle tissue.     

Strategies and methodology of marine diodiversity studies

This paper reviews major global and regional international approaches to inventory and monitoring of biological diversity. The current strategy of studying marine biodiversity is outlined. We also discuss the methodology of marine biota inventory at the regional level within the framework of the long-term biodiversity studies in the West and North Pacific Ocean that are undertaken by the international institutions Census of Marine Life, DIWPA, and NaGISA. The paper also contains data on the biological diversity of Russian Far East seas.     

Divergence of mitochondrial DNA in a population of sockeye salmon (Oncorhynchus nerka Walbaum) from Azabache'e lake (Kamchatka)

Variability of three PCR-amplified mtDNA regions was examined in five populations of sockeye salmon from Azabach'e Lake. Eighteen haplotypes were detected in 144 fish. Significant differences were found between seasonal races of sockeye salmon spawning in the lake. The short time of independent divergence between the seasonal races indicates that these races formed independently in each spawning region. No difference in mtDNA between lake samples of early sockeye salmon (subisolates) was revealed, which confirms the existence of gene flow between them. A high level of differences between the sockeye salmon spawning in the lake and spawning in the tributaries of the lake, the Bushuev and Lotnaya rivers, suggests that there were no migration between them during many generations and that the nature of spawning grounds (lake or river) is essential for within species differentiation in this species.     

Morphology of the Respiratory Trees in the Holothurians Apostichopus japonicus and Cucumaria japonica

The morphology of the respiratory trees in the holothurians Apostichopus japonicus and Cucumaria japonica was studied using histochemical and electron microscopic techniques. The epithelium of the respiratory tree cavity in A. japonicus consists of columnar cells about 17–20 m high. In C. japonica, this epithelium is composed of two cell types: bulbous cells embedded in the connective tissue layer and secretory cells; cells are 1–12 m high. A characteristic feature of cells of the respiratory tree cavity epithelium in these species is the presence of numerous phagosomes and coated vesicles in the apical cytoplasm. The cell surface has many microvilli and a single cilium. Cells of the coelomic epithelium contain vacuoles in the apical part and myofibrils in the basal region; the thickness of this epithelium in A. japonicus and C. japonica is 9–16 and 10–30 m, respectively. Based on the different structure of the respiratory trees and the absence of hemocytes in A. japonicus, it is suggested that the holothurian species studied have different routes of oxygen transport from the environment to the internal organs.     

Effect of a culturing method and growth phase on composition of lipopolysaccharides in Yersinia pseudotuberculosis

The effects of the culturing method (suspension cultures in a liquid nutrient broth or colonies on a solid agarized medium) and the growth phase on the lypopolysaccharide (LPS) composition of Yersinia pseudotuberculosis (O:Ib serovar, strain KS 3058) grown in cold (5 degrees C) were studied. The amount the LPS synthesized by cells depended on the bacteria growth phase for both media. The LPS acylation degree was constant, whereas the length of the O-specific polysaccharide chain varied with the culture age and achieved maximum in the stationary growth phase for both media. The bacteria culturing on the nutrient agar stimulated more intensive synthesis of LPS, which were extracted more easily, had longer polysaccharide O-chains, and were more toxic than LPS of the bacteria cultured in the liquid medium. It was proposed that the culturing of Yersinia pseudotuberculosis in cold as colonies on the agar surface causes an increase in the bacterial virulence.