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This study prepared an elastic material with an infrared (IR)-transmitting property based on the structural features of algae oils. The bulk copolymerization of elemental sulfur and unsaturated hyd...

Sulfur-based polymeric materials were obtained from surplus feedstock; elemental sulfur; and sustainable algae oil, Botryococcene, via inverse vulcanization. Reactions of elemental sulfur and Botry...

Aurantiochytrium limacinum 4W-1b (AL4W-1b) is a newly discovered microalgal strain with unique features. In the present study, we investigated the effects of ethanol extracts of AL4W-1b on lipopolysaccharide- (LPS-) induced inflammatory responses in RAW264 murine macrophage cells. Pretreatment of RAW264 cells with the AL4W-1b extract significantly reduced the production of LPS-induced nitric oxide (NO) and the expression of proinflammatory cytokine genes, including tumor necrosis factor α, interleukin- (IL-) 1β, and IL-6. Treatment with the AL4W-1b extract also decreased the production of IL-1β and IL-6. These results suggest that AL4W-1b might have anti-inflammatory effects in RAW264 cells. The NF-κB inhibitor, BAY 11-7082, synergistically prevented LPS-induced NO production after pretreatment with the AL4W-1b extract. Thus, the AL4W-1b extract may affect not only the NF-κB pathway but also other inflammatory pathways. To the best of our knowledge, this is the first study to report the anti-inflammatory effects of AL4W-1b extract and its mechanism of action in LPS-stimulated murine macrophage cells.

In this study, the effects of an ethanolic extract of Aurantiochytrium mangrovei 18W-13a strain (AM18W-13a) on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264 murine macrophages were studied. Pre-treatment with the AM18W-13a extract significantly suppressed the LPS-induced production of nitric oxide and pro-inflammatory cytokines. RAW264 cells treated with the AM18W-13a extract for 1 and 24 h were subjected to DNA microarray analyses for detecting the differentially expressed genes. The treatment of RAW264 cells with the AM18W-13a extract for 24 h significantly suppressed the expression of several genes associated with inflammation or chemotaxis. Furthermore, treatment with the AM18W-13a extract for 1 h suppressed the expression of Pde4b, but induced the expression of Egr2 and Egr3 in RAW264 cells. Additionally, the AM18W-13a extract significantly enhanced the expression of certain anti-inflammatory mediators. This study is the first report of the anti-inflammatory effects of the AM18W-13a extract and its mechanism of action in LPS-stimulated murine macrophages.

The aim of the present study is to obtain bio-oil from Botyococcus (B.) Braunii residue after B. Braunii oil (Bot-oil) extraction. For this, one of a probable method is fast pyrolysis, in which the effect of zeolite catalyst was examined. From Py-GC/MS analyses at 550 °C using H-ZSM-5 (80) (Z80) catalyst, total selectivities of aromatic and aliphatic hydrocarbons accounted for 88.6%, being much higher than 35.2% without catalyst. At fast pyrolysis using reactor, the organic liquid product (bio-oil) yield was found to be above 30%, approximately 3 times higher than that of Jatropha residue. The higher heating value (HHV) of the liquid product was approximately 35–37 MJ/kg, which was close to a HHV value of crude triglyceride. The highest overall hydrocarbon yield was 24.58% at 600 °C. In order to briefly compare with fast pyrolysis, hydrothermal liquefaction (HTL) of the residues under H2 pressure conditions was tried using PtRe/SiO2–Al2O3 catalyst, which has been extremely effective for hydrocracking of B. Braunii oil into aviation-range fuel. In the HTL of the B. Braunii residue at 400 °C, the hydrocarbon yield was 36.8% which was a little higher yield than that from pyrolysis. The n-alkanes predominantly formed over aromatic hydrocarbons, due to lower temperature of 400 °C and the catalyst different from pyrolysis. Postulated scheme was presented through cracking, hydrodeoxygenation and dehydroaromatization.

Renewable green aviation and diesel-type alkanes can be produced by hydrocracking of Botryococcus braunii oil (Bot-oil) and squalane oils with Pt–Re/SiO2–Al2O3 (SA) catalysts, which are active at 310–340 °C and the weight ratio of the oil/catalyst of 10. For purified Bot-oil on Pt–3 wt % Re/SA at 330 °C, the highest aviation fuel-range hydrocarbon (C10–C15) yield of 50.2% was achieved, with diesel-range hydrocarbons (C16–C20) of 16.7% yield. The re-modified Pt/SA catalysts are also active for hydrocracking of squalane as the model compound of algae oil, and the C10–C20 hydrocarbon yield of 68.8% was obtained. The Pt–Re catalyst was found to be stable for the second regeneration cycle, even with the use of crude Bot-oil. Investigation of catalyst natures indicates that metallic Pt and Re are independently present on the surface, but synergism of these two metals could play an important role in the hydrocracking reaction. The reaction pathway involves the C–C bond scission reaction via a carbenium ion forme...

Many of the genes that control photosynthesis are carried in the chloroplast. These genes differ among species. However, evidence has yet to be reported revealing the involvement of organelle genes in the initial stages of plant speciation. To elucidate the molecular basis of aquatic plant speciation, we focused on the unique plant species Chara braunii C. C. Gmel. that inhabits both shallow and deep freshwater habitats and exhibits habitat-based dimorphism of chloroplast DNA (cpDNA). Here, we examined the "shallow" and "deep" subpopulations of C. braunii using two nuclear DNA (nDNA) markers and cpDNA. Genetic differentiation between the two subpopulations was measured in both nDNA and cpDNA regions, although phylogenetic analyses suggested nuclear gene flow between subpopulations. Neutrality tests based on Tajima's D demonstrated diversifying selection acting on organelle DNA regions. Furthermore, both "shallow" and "deep" haplotypes of cpDNA detected in cultures originating from bottom soils of three deep environments suggested that migration of oospores (dormant zygotes) between the two habitats occurs irrespective of the complete habitat-based dimorphism of cpDNA from field-collected vegetative thalli. Therefore, the two subpopulations are highly selected by their different aquatic habitats and show prezygotic isolation, which represents an initial process of speciation affected by ecologically based divergent selection of organelle genes.

To gain genetic insights into the biosynthesis of botryococcene oils in Botryococcus braunii race B, a transcriptome dataset of the BOT-22 strain containing 27,427 non-redundant sequences assembled from 209,429 complementary DNA reads was obtained via high-throughput 454 sequencing. Relatively reliable prediction of the gene product was feasible for 725 non-redundant sequences based on homology to previously characterized database sequences. Regarding the botryococcene oil biosynthesis, genes putatively associated with the mevalonate-independent isoprenoid biosynthesis pathway were retrieved, while no genes were found for the mevalonate pathway, suggesting that botryococcenes are biosynthesized through the mevalonate-independent pathway in B. braunii. All transcriptome sequences have been deposited in the GenBank/EMBL/DDBJ database.

Two strains of Raphidiopsis Fritsch et Rich were isolated from a fishpond in Wuhan city, China and rendered axenic, and characterized by a combination of morphological, physiological, biochemical and genetic methods. Morphologically the strains were identified as Raphidiopsis mediterranea Skuja (straight trichomes) and R. curvata Fritsch et Rich (coiled trichomes). These two strains demonstrated slight differences in optimal temperature range and GC content, while sharing some common characteristics including inability to grow hetertrophically, similar salinity tolerance (up to 0.78%) and an identical fatty acid composition. Cyanotoxins were not found in the strain of R. mediterranea, however, the strain of R. curvata contained both deoxycylindrospermopsin and cylindrospermopsin. Phylogenetic affiliations inferred from 16S rRNA gene sequences demonstrated that both Raphidiopsis strains clustered with Cylindrospermopsis, demonstrating their phylogenetic ties to Nostocaceae. (c) 2007 Elsevier B.V. All rights reserved.

The contents of mycosporine-like amino acids (MAAs) were compared in the two color morphs (dark-gray and brown colonies) of the tropical ascidian Didemnum molle (Herdman, 1886), which harbors the photosymbiotic prokaryote Prochloron. The colonies of each color morph were exclusively distributed in shallow reef lagoons at the different sites. Spectroscopic and chromatographic analyses showed that the Prochloron cell density and MAA concentration in the dark-gray colonies were an estimated 1.4 and 2.4 times higher, respectively, than in the brown colonies. The significant difference in MAA contents between the color morphs was primarily due to the difference in shinorine contents (p < 0.01, Mann–Whitney U-test). The high concentration of MAAs in the dark-gray colonies may provide better conditions for Prochloron cells, compared to the brown colonies with lower MAA concentrations.

The taxonomic status ofNitella comptonii (Charales, Characeae) is not well understood because this species has not been recorded since the early 20th century, and detailed examinations of fully mature individuals have not been performed. Recently, we collected fully matureN. comptonii from the Okinawa Islands in Japan. These exhibited a distinctive fertile spherical head in the axils, and their vegetative and reproductive structures were consistent with those in the original description of the species. In 1965 in his ‘A revision of the Characeae’, R. D. Wood assignedN. comptonii as a subspecies ofN. pseudoflabellata. In our study, scanning electron microscopic analysis ofN. comptonii oospores revealed that external and internal oospore morphology ofN. comptonii was clearly different from that ofN. pseudoflabellata. In addition, multiple DNA phylogeny using the concatenated sequences of the chloroplastrbcL,atpB, andpsaB genes, and nuclear 5.8S ribosomal RNA gene and internal transcribed spacer reg...

The genetic combinations between mycobionts and photobionts in Parmotrema tinctorum collected from ca. 60 km2 of the Shimizu district, of Shizuoka City in Japan was investigated based on ITS rDNA sequences. This lichen produces apothecia quite rarely, and in principle propagates vegetatively by isidia. The genetic diversity of the mycobiont comprised four types, while that of the photobiont comprised 21 types. There were 28 different combinations between mycobiont and photobiont. All the photobionts were identified as Trebouxia corticola (s. lat.), based on both molecular phylogenetic results and morphological observation of culture strains obtained in this study. Therefore, P. tinctorum is considered to be highly selective toward the photobiont. The 28 combinations from the small area represent an unexpectedly high diversity, because P. tinctorum is thought to propagate vegetatively. Four possible mechanisms to account the high genetic combinations are suggested: i.e., photobiont exchange, fusio...

Carteria palmata Suda, Nozaki & M.M. Watanabe sp. nov. from Japan has been examined by light and electron microscopy using cultured materials. The cells are nearly spherical, 16–22 µm long, and 15–21 µm wide. The chloroplast is single and stellate cup-shaped, containing a basal and palm-shaped pyrenoid without coherent starch grains. The pyrenoid matrix is traversed by reticulated chloroplast thylakoid lamellae, and there is no clear border between the pyrenoid matrix and the chloroplast stroma. In the chloroplast, many microtubule-like structures exist around the pyrenoid. A conspicuous eyespot is located in the middle to anterior surface of the chloroplast. Four contractile vacuoles are located in the anterior cytoplasm under the flagellar bases. The flagellar apparatus is arranged similarly to the Carteria group I type, which has eight connecting fibres, each interlinking two adjacent basal bodies at the distal and proximal ends. In addition to these fibres, one distal connecting fibre interli...

Twenty-six axenic strains of planktonic Anabaena with coiled trichomes belonging to 13 species were investigated by analyzing the pattern and content of their fatty acid composition, and by comparing their fatty acid composition with their morphological properties. In general, the planktonic Anabaena with coiled trichomes contained 14:0, 16:0, 16:1(cis-), 18:0, 18:1, 18:2, and 18:3(alpha) as their major fatty acid component, and were classified as Type 2 according to the Kenyon-Murata System. The Type 2 was further divided into two subtypes: Type 2A with 16:2 and 16:3, and Type 2B without 16:2 and 16:3. Among these Anabaena strains with coiled form, A. oumiana (NIES-73 and Ana Kas1) and A. eucompacta (Ana Chiba) contained Type 2B fatty acid composition, and other strains contained Type 2A. Among the strains with the latter type, A. circinalis (Ana Da) and A. curva (Ana Ao) had low levels of 18:3(alpha). Most Anabaena strains with coiled trichomes showed a strong correlation between morphological characteristics and fatty acid composition.

SUMMARY The electron microscopy of zygote formation and the early stages of zygote germination in Nephroselmis olivacea Stein are presented. Although the gametes differ behaviorally during the early stages of gamete fusion, the alga is isogamous. The minus gamete settled on the substrate, and attached with its left side. The plus gamete swam to the minus gamete, attached ventral to the right side of the minus gamete, while slightly on its left side, and plasmogamy started. No specialized organelle for gamete fusion was seen using either scanning or transmission electron microscopy. Gametic fusion was uniform; the right side of the minus gamete always fused with the ventral, slightly left side of the plus gamete, which suggests the participation of the d-rootlets of the flagellar apparatus of the two gametes. Body scales were retained throughout the entire sexual process. Before karyogamy, a network of endoplasmic reticulum developed between the nuclei. This position corresponded to the contractile vacuole of the plus gamete. Fusion proceeded as the minus gamete was drawn to the plus gamete and resulted in a hemispherical zygote. Fibrous material appeared on the cell surface, embedding the body scales to form a layer that thickened and contributed to the strong adhesion of the zygote to the substrate. During this stage, karyogamy was completed. A thick zygotic wall composed of two layers, an electron-dense outer layer and a straticulate electron-lucent inner layer developed beneath the layer of fibrous material and scales. Zygote germination was induced. After the first meiotic division, the layer of fibrous material and scales ruptured and the inner layer of the zygotic wall thinned, allowing the emergence of two germ cells. They had newly formed scales and two starch grains, but no typical pyrenoid.

Cylindrospermopsis raciborskii is a planktonic, nostocalean cyanobacterium, which produces an alkaloid heptatoxin, cylindrospermopsin. We performed morphological observations, 16S rDNA sequence analysis, PCR fingerprint analysis of short tandemly repeated repetitive (STRR) sequences, temperature tolerances and toxin analysis to characterize 24 strains of this toxic cyanobacterium isolated from Thailand and Japan. All strains shared common morphological traits characteristic of C. raciborskii and showed high 16S rDNA sequence similarity, forming a defined cluster together with the reference strains from Australia. In particular, some of the Thai strains shared 99.9% to 100% similarity with the Australian strains. Various combinations of STRR primers revealed different and unique DNA band patterns among strains of C. raciborskii. The phylogenetic tree revealed two main clusters of C. raciborskii strains, the Thai/Japan-Shinobazugaike cluster (cluster I) and the Japan-Gonoike cluster (cluster II). Cluster I was further divided into two subclusters, A (only Thai strains) and B (one Thai strain and the Japan-Shinobazugaike strains). Thus, the results from 16S rDNA and STRR analyses showed no clear geographical distinction between Japanese and Thai strains and between Thai and Australian strains. Thai strains were separated into adaptive and non-adaptive groups to low temperature (15 and 17.5 degrees C) and Japanese strains were composed of only low-temperature-adaptive ones. The toxin cylindrospermopsin was detected in some strains of cluster I-A and in one strain of cluster II. We conclude that C. raciborskii is a species that has recently begun to invade, and a species with different physiological strains or ecotypes in temperature tolerance; the toxin is synthesized without any relation to phylogenetic or genetic clusters and to geography.

Recombination has been suggested to be an important factor for the genetic variation of bacterial genes, but few studies have dealt with intragenic recombination between the same or closely related species of cyanobacteria. Here we provide strong evidence for recombination in the microcystin synthetase (mcy) gene cluster of the toxic cyanobacteria Microcystis spp. This gene cluster contains 10 genes (mcyA to J) that encode a mixed polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS) complex. mcy gene sequences were determined for four selected regions (within mcyA, D, G, and J) within the mcy gene cluster from 1 Canadian and 10 Asian toxic Microcystis and compared with previously published mcy sequences. Split decomposition analysis indicated a reticulate phylogeny of mcyA, and several potential recombination tracts of mcyA were identified by the RDP analysis and a runs test implemented in GENECONV. In contrast, no recombination was detected in the mcyD, G, and J sequences. However, discrepancies among the four mcy gene genealogies were evident from the results of independent split decomposition analyses, which were further supported by incongruence length difference (ILD) tests. Taken together, these findings suggest that both intragenic and intergenic recombination within the mcy gene cluster contributes to the genetic diversity of the mcy genes of Microcystis spp.

Toxic effects of dichloromethane and trichloroethylene on the growth of three planktonic green algae, Chlorella vulgaris NIES227, Selenastrum capricornutum NIES35, and Volvulina steinii NIES545, were examined. The two organic solvents at concentrations of up to a hundred-fold the Japanese national effluent standards did not affect the growth of the former two algae, but at just a tenth of the concentration of the standards were fatal to the latter. Even water with a relatively low concentration of pollutants, which meets the effluent standards for human health, is not necessarily harmless to the natural ecosystem.

Microsporidia are intracellular parasitic microbes, which were once thought to be among early diverging eukaryotes, mainly because they lack mitochondria. However, this evolutionary scheme has been challenged by protein-based molecular phylogenetic studies, which suggest a more recent origin of the Microsporidia which clustered Microsporidia with or within ‘true’ fungal lineages. However, most of these studies did not include sequences from basal fungal phyla ( Chytridiomycota and Zygomycota ), and unrepresentative taxon sampling could have resulted in misleading relationships being suggested. To further investigate the evolutionary origin of Microsporidia relative to Fungi we performed molecular phylogenetic analyses with newly determined RPB1 (DNA-dependent RNA polymerase II largest subunit) and EF-1α (translation elongation factor I alpha) including sequences from basal fungi. Although the phylogenetic position of Microsporidia in the EF-1α tree still might be misplaced due to the unusually high rate of sequence divergence of the microsporidian EF-1α gene, the phylogenies recovered based on these two protein sequences do not provide strong evidences for a close relationship between Microsporidia and Fungi. Moreover, we have identified within the EF-1α genes a characteristic two amino acid deletion conserved in all fungal sequences currently available, whereas this deletion is absent in microsporidian sequences. These results argue against the view of Microsporidia as highly degenerate fungi, and whether Microsporidia and Fungi are sister taxa remains unresolved.

A polyphasic approach was used to clarify the taxonomy of the water-bloom-forming oscillatorioid cyanobacteria. Seventy-five strains of oscillatorioid cyanobacteria were characterized by 16S rDNA sequence analysis, DNA base composition, DNA-DNA hybridization, fatty acid composition, phycobilin pigment composition, complementary chromatic adaptation, morphological characters, growth temperature and salinity tolerance. Phylogenetic analysis based on 16S rDNA sequences divided the strains into six groups, all of which were clearly separated from the type species of the genus Oscillatoria, Oscillatoria princeps Gomont NIVA CYA 150. Therefore, these strains should be classified into genera other than Oscillatoria. Groups I-III were closely related to one another and groups IV-VI were distinct from one another and from groups I to III. Group I was further divided into two subgroups, group I-pc, which includes strains containing only phycocyanin (PC), and group I-pe, which includes strains containing large amounts of phycoerythrin (PE) in addition to PC. This phenotypic distinction was supported by DNA-DNA hybridization studies. Based on the properties examined herein and data from traditional, botanical taxonomic studies, the groups and subgroups were classified into single species and we propose either emended or new taxonomic descriptions for Planktothrix agardhii (type strain NIES 204T), Planktothrix rubescens (type strain CCAP 1459/22T), Planktothrix pseudagardhii sp. nov. (type strain T1-8-4T), Planktothrix mougeotii (type strain TR1-5T), Planktothricoides raciborskii gen. nov., comb. nov. (type strain NIES 207T), Tychonema bourrellyi (type strain CCAP 1459/11BT) and Limnothrix redekei (type strain NIVA CYA 277/1T).

A partial list of desmids from lakes in the Experimental Lake Area, north-western Ontario, Canada, is presented with taxonomic notes. Eighty-four taxa from the genera Actinotaenium and Cosmarium are recorded. Forty-seven of these are new to the algal flora of the Province of Ontario. Light and scanning electron microscope pictorial references are given and morphological features of some species are discussed.

(2002). Killing of Microcystis by an amino acid: results of laboratory and enclosure experiments. SIL Proceedings, 1922-2010: Vol. 28, No. 2, pp. 1147-1150.

An amino acid (L-lysine) was screened against eighteen strains ofCyanophyceae, Bacillariophyceae and Chlorophyceae. OnlyMicrocystis strains (Cyanophyceae) were sensitive tolysine; other strains were not affected. Cells of sevenMicrocystis strains (106 cellsmL−1) were completely killed within 48h by lysine at concentrations between 0.6 and 5.0 mgL−1. Two Microcystis strains wereinhibited by 92 and 98 %. Similar results were obtained when lysine malonateandlysine copper were used as algicides. Microcystis specieswere killed by lysine malonate at concentrations between 0.6 and 5 mgL−1, and by lysine copper at concentrations between 0.5and 20 mg L−1.

Fifty axenic strains of planktonic Anabaena, including 24 strains of the straight form and 26 strains of the coiled form, were examined for their DNA base composition (GC content). The taxonomic value of their GC content at species level was evaluated by comparing their morphological, physiological and biochemical properties. The DNA base composition determined for all fifty strains ranged from 35.9 to 56.4 mol% GC. The straight-form strains were in the range of 35.9-56.4 mol% GC, while coiled forms were in the range of 38.1-50.3 mol% GC. In general, strains assigned to the same species showed similar DNA base composition. However, of three strains of A. affinis Lemmermann that were separated into two categories, two had 40.6-40.9 mol% GC, and the third strain 45.6 mol% GC. It is noteworthy that the DNA base composition of the newly established species A. eucompacta Li et Watanabe was 45.5 mol% GC, which differed from 39.5 mol% GC of the morphologically close species, A. compacta (Nygarrd) Hickel.

Fifty axenic strains of planktic Anabaena were determined for their physiological growth characteristics, including growth temperature range, salinity tolerance and heterotrophic ability. The taxonomic value of these physiological properties was evaluated by combining with their morphological characteristics. Except for A. affinis LEMMERMANN, all species showed good correlation between the morphological and growth temperature characteristics. A. affinis could be distinguished into two groups by temperature characteristics. An examination of salinity tolerance showed that most species could grow in salinity up to 1/5 (0.78% of salinity) or 1/3 sea-water medium (1.28% of salinity). Two species (A. solitaria and A. circinalis) grew only up to 1/10 sea-water medium (0.43% of salinity). None of planktic species ofAnabaena grew either in dark with addition of organic substances such as organic acids and sugars, or in the light with 3'-(3-4-dichlorophenyl)1', 1'-dimethyl urea (DCMU) and the above organic substances. The newly established species A. eucompacta Li et WATANABE was shown to have distinctly different temperature and salinity properties from the morphologically similar species, A. compacta (NYGAARD) HICKEL.

A strain of Raphidiopsis (Cyanobacteria) isolated from a fish pond in Wuhan, P. R. China was examined for its taxonomy and production of the alkaloidal hepatotoxins cylindrospermopsin (CYN) and deoxy-cylindrospermopsin (deoxy-CYN). Strain HB1 was identified as R. curvata Fritsch et Rich based on morphological examination of the laboratory culture. HB1 produced mainly deoxy-CYN at a concentration of 1.3 mg(.)g(-1) (dry ut cells) by HPLC and HPLC-MS/MS. CYN was also detected in trace amounts (0.56 mug(.)g(-1)). A mouse bioassay did not show lethal toxicity when tested at doses up to 1500 mg dry weight cells(.)kg(-1) body weight within 96 h, demonstrating that production of primarily deoxy CYN does not lead to significant mouse toxicity by strain BB I. The presence of deoxy-CYN and CYN in R curvata suggests that Raphidiopsis belongs to the Nostocaceae, but this requires confirmation by molecular systematic studies. Production of these cyanotoxins by Raphidiopsis adds another genus, in addition to Cylindrospemopsis, Aphanizomenon, and Umezakia, now known to produce this group of hepatotoxic cyanotoxins. This is also the first report from China of a CYN and deoxy-CYN producing cyanobacterium.

The growth and grazing characteristics of Poterioochromonas malhamensis (Pringsheim) Peterfi (= Ochromonas malhamensis Pringsheim) (ca. 8 μm) feeding on phytoplankton, including the cyanobacteria Synechococcus sp. (ca. 2 μm) and Microcystis viridis (A. Brown) Lemmermann (ca. 6 μm) and the green alga Chlorella pyrenoidosa Chick (ca. 13 μm), were investigated in laboratory experiments involving the following treatments: (1) light without added algal prey (autotrophy), (2) light with added algal prey (mixotrophy), and (3) dark with added algal prey (phagotrophy). There were significantly higher cell numbers under mixotrophic and phagotrophic growth than under autotrophic growth. With phytoplankton as food, growth rates under both mixotrophy and phagotrophy were about two or three times higher than those under autotrophy, indicating that the algal diets were readily able to support the population growth of P. malhamensis. There were no significant differences in growth rate between mixotrophic and phagotrophic cultures during exponential growth. The ingestion rate of P. malhamensis with algal prey was also similar under both continuous light and dark. Poterioochromonas malhamensis ingested on average 0.27 M. viridis cells·flagellate−1·h−1 and 0.18 C. pyrenoidosa cells·flagellate−1·h−1 in continuous light and 0.25 M. viridis cells·flagellate−1·h−1 and 0.18 C. pyrenoidosa cells·flagellate−1·h−1 in continuous dark during exponential growth. The results showed that light had no effect on the growth and ingestion rates of P. malhamensis for phagotrophy during exponential growth. However, phagotrophic populations of P. malhamensis were incapable of growth in continuous darkness for longer than 5 days. Populations of P. malhamensis showed no increase when prey was added again after 4 days in continuous darkness, indicating that light is necessary for sustained phagotrophic growth of P. malhamensis. The study suggests that P. malhamensis, which has strong tolerance for light, is light dependent for phagotrophy.

A strain of Cylindrospermopsis (Cyanobacteria) isolated from a fishpond in Thailand was examined for its taxonomy based upon morphology and 16S rRNA gene sequence. It was also examined for production of the hepatotoxic cyanotoxin called cylindrospermopsin (CYN) and deoxycylindrospermopsin (deoxy-CYN). The strain (CY-Thai) was identified as C. raciborskii (Woloszynska) Seenaya and Subba Raju based upon morphological examination which was confirmed by 16S rRNA gene sequences and phylogenetic comparisons based upon its 16S rRNA gene. The alkaloid heptatotoxin CYN was confirmed using mouse bioassay, HPLC and HPLC-MS/MS while deoxy-CYN was confirmed using HPLC-MS/MS. The mouse bioassay gave a minimum lethal dose at 250 mg dry weight cells/kg body weight within 24 h and 125 mg/kg at 72 h, with signs of poisoning the same as in literature reports for CYN. HPLC chromatographic comparison of the CY-Thai toxin with standard CYN gave the same retention time and an absorbance maximum at 262 nm. HPLC-MS/MS confirmed the presence of CYN (M+H 416) and deoxy-CYN (M+H 400). The CYN content in strain CY-Thai was estimated at 1.02 mg/g and approximately 1/10 of this amount for deoxy-CYN. This is the first report from Asia of a CYN, deoxy-CYN producing Cylindrospermopsis raciborskii.

Twenty-four axenic strains of planktonic Anabaena with straight trichomes, assigned to 7 species, were investigated by analyzing the pattern and content of their fatty acid composition and comparing their fatty acid composition with their morphological properties. In general, the fatty acids in planktonic Anabaena contained 14:0, 16:0, 16:1(cis-), 18:0, 18:1, 18:2, and 18:3(alpha) as their major components, and were classified as Type 2 according to the Kenyon-Murata system. These strains were further divided into 2 subtypes: 18 strains belonging to Type 2A, which contains 16:2 and 16:3, and 6 strains to Type 2B, which lacks 16:2 and 16:3. Fatty acid compositions of strains of A. solitaria, A. smithii, and A. kisseleviana closely corresponded to morphological properties; however, 10 strains of A. planctonica were divided into 4 clusters, and 3 strains of A. affinis into 2 clusters. These clusters should be taxonomically evaluated based on other aspects such as genetic characteristics.

The genus Synechococcus (cyanobacteria), while containing morphologically similar isolates, is polyphyletic and organisms presently classified as such require reclassification into several independent genera. Studies based on analysis of 16S rRNA gene sequences have shown that members of the genus Synechococcus are affiliated to three of seven deeply branching cyanobacterial lineages. In addition, some strains do not appear to be associated with any of these lineages and may represent novel clades. In this report, a cyanobacterial phylogeny based on 16S rDNA sequences, including 14 newly sequenced Synechococcus isolates, is presented. One newly sequenced Synechococcus strain (PCC 7902) did not have any close relatives amongst cyanobacterial isolates currently contained in 16S rDNA sequence databases and was only loosely affiliated to a cyanobacterial lineage in which no other Synechococcus strains were found. Three hot-spring Synechococcus isolates, including two that were newly sequenced in this study (PCC 6716 and PCC 6717), formed an additional cyanobacterial lineage. These results indicated that Synechococcus species are affiliated to five of eight deeply branching cyanobacterial lineages. Part of the phycocyanin (PC) gene sequence (cpc), including the intergenic spacer (IGS) between cpcB and cpcA and the corresponding flanking regions (cpcBA-IGS), was used to investigate relationships between closely related Synechococcus isolates. Previously described PCR primers did not amplify this region from the majority of strains under investigation, so a new set of primers was designed that allowed amplification and sequencing of the cpcBA-IGS and flanking regions from 38 Synechococcus species. Phylogenetic analysis of this region was largely consistent with that obtained from 16S rDNA sequence analysis and revealed a relationship between the primary PC DNA sequence and the phycobilin content of cells.

The taxonomy of Aphanizomenon flos-aquae strain NH-5, a producer of cyanotoxins, was re-evaluated by comparison with six other Aphanizomenon strains using morphological characteristics and 16S rRNA gene sequences. Strain NH-5 was concluded to be improperly identified as Aph. flos-aquae based upon (1) lack of bundle formation in the trichomes, (2) location of akinetes next to heterocytes, (3) lower similarities (less than 97.5%) in the 16S rRNA gene sequences relative to Aph. flos-aquae strains, and (4) comparison within a phylogenetic tree constructed from 16S rRNA gene sequences. The Aphanizomenon strains investigated in this study are classified to four morphological groups as described by the classical taxonomy of Komarek & Kovacik (1989). This classification was supported from the phylogenetic results of 16S rRNA gene sequences. This study also discusses the generic boundaries between Aphanizomenon and Anabaena.

Fifty (50) strains of planktic species of Anabaena (cyanobacteria), including collections from Japan and China and from different culture collections, were induced to form akinetes at low temperature (15 °C). Their morphologies were then observed and described. Fourty seven strains successfully formed akinetes and these were classified into 20 species comprising seven with straight trichomes and 13 with coiled trichomes. Three strains, which did not form akinetes, were separated into two taxonomic groups, but could not be identified to any described species. In addition, a key to the planktic species of Anabaena described in the study is presented.

The biomass, species composition and diversity of epipelic algae in two small pools of contrasting physicochemical characteristics in Miyatoko Mire were studied in 1992 (pool 3 =site B4 and pool 50 =site D2). A total of 93 species and 67 species of epipelic algae occurred at sites B4 and D2, respectively. Considerable differences were observed between the two sites in the seasonal fluctuations of species number, biomass and dominant species. At site B4, little changed with species number during April–August and markedly increased in October, while biomass was largest in April and gradually decreased during June–October. Diatoms and desmids occupied 33–82% and 15–63% of total algal biomass, respectively. At site D2, species number and biomass were small in April just after the snow-thaw, and increased in June and decreased in August and October. Diatoms occupied 90–98% of total algal biomass. The species diversity was always higher at site D2 than B4. As a result of analyses of water chemistry in the two pools, pool B4 can be recognized as a habitat experiencing high disturbance frequency. It is predicted that pools experiencing frequent disturbance will have less epipelic algal biomass and diversity.