Development in culture of the diatomChaetoceros salsugineus from the Sea of Japan

The development of the diatomChaetoceros salsugineus from Amurskii Bay in the Sea of Japan was investigated in laboratory culture. It is shown that the intraspecific taxaC. salsugineus f.salsugineus, C. salsugineus f.curtus, andC. salsugineus f.solitarius correspond to particular stages in the development of this species in culture. Problems of the taxonomy and biology of this species are discussed. It is assumed that the life cycle ofC. salsugineus includes a benthic stage represented by resting cells.     

Effects of selenium on growth and ultrastructure of the marine unicellular alga <Emphasis Type="Italic">Dunaliella salina</Emphasis> (Chlorophyta)

This study examines the effects of selenium in concentrations of 0.01, 0.5, 1, 5, and 10 mg/liter on the growth and ultrastructure of the microalga Dunaliella salina. Selenium in concentrations of 0.01 and 0.5 mg/liter stimulated cell population growth, while the number of ultrastructural alterations was the same as in the control cells. At a selenium concentrations of 1 mg/liter, cell population growth slightly decreased by the end of the experiment, and there was some increase in the number of cells with damaged organoids and in the number of completely destroyed cells. As well, the excretory function of cell vacuoles was suppressed, and the autophagic activity of these vacuoles was activated to destroy the cytoplasm and nucleus. Concentrations of 5 and 10 mg/liter were toxic to D. salina, suppressing cell population growth and promoting extensive destructive changes. The threshold concentration of selenium for D. salina was 1 mg/liter, which is 1000 times greater than the maximum permissible concentration (MPC). The fact that the microalga was able to survive for several days in this concentration is indicative of its high resistance to selenium.     

The influence of ultra-low temperatures on marine microalgal cells

The development of cryopreservation methods for microalgae opens great prospects for marine biotechnology and aims to establish a bank of cryopreserved cultures. Eight of ten marine microalgae species used in this study (the diatoms, green, red, and golden algae), including five previously untested species, were successfully recovered after freezing to ultra-low temperatures (?196 °C) using penetrating (dimethyl sulfoxide, glycerol, and ethylene glycol) and non-penetrating (trehalose and polyvinylpyrrolidone) cryoprotectants. We found that ethylene glycol in combination with trehalose possessed the most effective cryoprotective activity among the algae cryoprotectants tested. However, the chief factor for the successful preservation of microalgal cells during freeze–thawing was shown to be the cooling rate. Cooling was performed in two ways: step or fast droplet freezing. The droplet freezing described here was effective only for cryopreserving green algae, whereas step freezing was optimal for all other algal species. Three diatoms of the genus Attheya were successfully cryopreserved for the first time, but none of the tested protocols had a positive result for the diatoms belonging to Pseudo-nitzschia. The failure may be explained rather by peculiarities in the cell wall composition (higher content of silica and fewer organic components) than by the specific (long and thin) shape of these cells. The pigment content in all of the studied species tended to decrease after thawing as compared with unfrozen cells and increase significantly during cell recovery. Cryosensitivity of marine algae depended on the differences in natural intrinsic characteristics rather than their taxonomic position.     

The development of Porphyridium purpureum (Bory de Saint-Vincent) Drew et Ross, 1965 (Rhodophyta) from Amursky Bay,Sea of Japan,in a laboratory culture

The growth of the microscopic red alga Porphyridium purpureum was experimentally studied in different culture media and at various levels of water salinity. The ability of this species to recover after cryopreservation was analyzed. It was revealed that the growth rate and generation time of P. purpureum during the exponential growth phase did not significantly differ between cultures on f medium and those on Goldberg’s medium. The species has been found to withstand salinity variations ranging from 8 to 32 vol %. Cryopreservation of P. purpureum cells using three-step freezing with trehalose as a cryoprotectant showed that the dynamics of cell density after thawing insignificantly differed from the control ones.     

The Morphological,Genetic and Physiological Characteristics of a Benthic Dinoflagellate of the Genus <Emphasis Type="Italic">Ostreopsis</Emphasis> Isolated from Coastal Waters of the Northwestern Sea of Japan

A previous molecular-genetic analysis of clonal cultures and single cells of Ostreopsis spp. that were isolated from Peter the Great Bay (the Sea of Japan) revealed three different genotypes according to the nucleotide sequences of ribosomal DNA (rDNA). Of these, Ostreopsis sp. 1 was earlier found only off the coast of Japan and described as being the most common and highly toxic. We have obtained further molecular evidence and have studied the morphological features of cells from one of the Ostreopsis strains with this genotype and some aspects of its growth at salinities of 24, 28, and 32‰. The results showed that in cells from the Russian coast of the Sea of Japan, the third apical (3') and the third precingular (3") plates do not adjoin one another, being separated by the elongated second apical (2') plate. Cells of Ostreopsis sp. 1 from the Russian coast are significantly larger than Ostreopsis sp. 1 cells with the same genotype from the coast of Japan. Salinity did not have a substantial effect on the growth of Ostreopsis sp. 1. The growth rate varied from 0.24 to 0.35 divisions per day, with maximum values at a salinity of 24‰. When salinity decreased to 24‰, the exponential growth phase was significantly extended and the maximum cell concentration doubled.     

Biotesting of water quality in Peter the Great Bay with the use of the microalga Dunaliella salina and embryos and larvae of the sea urchin Scaphechinus mirabilis

Comparative biotesting was performed using embryos and larvae of the sea urchin Scaphechinus mirabilis and the microalga Dunaliella salina. These two species were taken as test organisms for estimating water quality in areas of various anthropogenic loads. Seawater from Nakhodka and Vostok bays, as well as from the southwestern part of Peter the Great Bay (Sea of Japan) near the Tumen River mouth, was tested. Water from Vostok and Nakhodka bays had a harmful effect on embryonic and larval development of the sea urchin. The algal culture kept in the water of Vostok Bay was depressed throughout the experiment, while development of the alga in the water from Nakhodka Bay hardly differed from the control but was unstable. Water from the southwestern part of Peter the Great Bay did not have any significant harmful effect on both test organisms. Embryos and larvae of the sea urchin S. mirabilis were several orders more sensitive to salinity changes and content of toxic agents; they responded more readily to changes in water quality than D. salina cells. Correspondingly, embryos and larvae of the sea urchin S. mirabilis were found to be a preferable test organism for assessment of pollution in various marine environments.     

The morphology,development, and state of the photosynthetic apparatus of the diatom <Emphasis Type="Italic">Attheya ussurensis</Emphasis> Stonik,Orlova et Crawford, 2006 (Bacillariophyta) in long-term culture

The development of the marine benthic diatom Attheya ussurensis (Bacillariophyta) isolated from Ussuriisky Bay (Sea of Japan) was examined in laboratory culture. It was found that the development of A. ussurensis was characterized by a short lag phase or its absence and high growth rates (about 1.7 divisions per day) during the exponential phase. Resting cells were formed during the stationary growth phase. Morphological and ultrastructural changes in the cells of A. ussurensis during its life cycle are described based on light and electron microscopic observations. Resting cells retained their photosynthetic activity when stored in the dark for a long period of time (up to 1 year) at a temperature of 4–6°C. After 30, 60, 90, 120, 150, and 180 days of storage under such conditions, the culture of A. ussurensis was capable of regeneration due to the existence of the resting cell stage in the life cycle of the microalga.     

Content of photosynthetic pigments, growth, and cell size of microalga Phaeodactylum tricornutum in the copper-polluted environment

Effects of copper at concentrations of 0.13 and 0.25 mg/l on content of photosynthetic pigments, growth, size characteristics, and cell shape of Phaeodactylum tricornutum (Bacillariophyta) microalga were studied. The inhibitory effect of copper on growth parameters was shown to become stronger with increasing concentration of copper in the growth medium. In spite of considerable retardation of cell growth, the concentrations examined had no effect on the content of photosynthetic pigments though affected some morphometric parameters.     

<Emphasis Type="Italic">Dunaliella salina</Emphasis> (Chlorophyta) as a Test-Object for Assessment of Detergent Pollution of a Marine Environment

The dynamics of the number of the microalga Dunaliella salina, depending on the age of the matrix culture, the number of cells, and the time of toxicant administration in the culture medium and on oxygen production as a parameter of the functional condition of the dunaliella, was studied in solutions of sodium dodecylsulfate (SDS) containing 0.1, 1, and 10 mg/l of the detergent. The parameters at which the application of the considered test-object allowed determination of the most exact information on the environment quality and toxicity of substances were determined. It was shown that the SDS in concentrations of 0.1 and 1 mg/l did not affect significantly the growth of the microalga, and an inhibiting effect was recorded at a toxicant content of 10 mg/l.Original Russian Text Copyright ¢ 2005 by Biologiya Morya, Markina, Aizdaicher.     

Influence of laundry detergents on the abundance dynamics and physiological state of the benthic microalga <Emphasis Type="Italic">Attheya ussurensis</Emphasis> (Bacillariophyta) in laboratory culture

This study examines the influence of the detergents “Obychnyi poroshok” and “Ariel” (at 0.1, 1, and 10 mg/l) on the growth and physiological state of the benthic marine microalga Attheya ussurensis. Cell number, growth rate, and oxygen productivity turned out to be the most sensitive characteristics for evaluation of toxic effects, while the pH of the culture medium and the contents of chlorophyll a and carotenoids were more tolerant to detergent. Toxicants in concentrations of 0.1 and 1 mg/l had a weak inhibitory effect on the microalga A. ussurensis; at 10 mg/l, the detergent Ariel exerted a greater inhibitory effect on the microalga than Obychnyi poroshok did.