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The psychrophilic freshwater alga Hydrurus foetidus (Villars) Trevisan has previously resisted laboratory culturing in liquid media. We investigated the use of microbiological techniques adapted to specific requirement for low temperature and high turbulence of the alga. We found that successful culturing required cleaning steps, where pieces of the alga were dissected out and plated on agar under cold conditions. From here, unialgal colonies could be isolated and inoculated into liquid media under appropriate conditions. Turbulence, created by a laboratory shaker, is critical. Sufficient light (30-100 µmol m s) and low temperature (here 2-3°C) are necessary. This rather common but highly under-investigated freshwater alga has potential for basic and applied research when available as laboratory cultures. [ABSTRACT FROM AUTHOR]

The cryptomonads is a well-defined lineage of unicellular eukaryotes, composed of several marine and freshwater groups. However, the evolutionary relationships among these groups are unclear due to conflicting inferences between morphological and molecular phylogenies. Here, we have inferred the evolutionary relationships among marine and freshwater species in order to better understand the importance of the marine–freshwater boundary on the historical diversification patterns of cryptomonads. We have constructed improved molecular phylogenies by taking into account rate variation both across sites and across sequences (covarion substitutions), and by analysing the vast majority of publicly available cryptomonad 18S rRNA sequences and related environmental phylotypes. The resulting phylogenies included 55 sequences, and revealed two novel freshwater cryptomonad clades (CRY1 and CRY2) and a large hidden diversity of cryptomonads. CRY1 was placed deeply within the cryptomonad phylogeny together with all the major freshwater lineages (i.e. Goniomonas and Cryptomonas), while CRY2 was placed within a lineage of marine species identified as Plagioselmis-like with the aid of a new sequence generated from a cultured species. The inferred phylogenies suggest only few successful marine–freshwater transitions over the history of cryptomonads. Most of the transitions seem to have occurred from marine to fresh waters, but re-colonizations of marine habitats have also taken place. This implies that the differences in the biogeophysical conditions between marine and fresh waters constitute a substantial barrier for the cross-colonization of these environments by cryptomonads. [ABSTRACT FROM AUTHOR]

Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophytes, diatoms, cryptophytes, and prasinophytes. Their major plastid type with the accessory pigment peridinin is found in the vast majority of photosynthetic species. Some species of dinoflagellates have other aberrantly pigmented plastids. We sequenced the nuclear small subunit (SSU) ribosomal RNA (rRNA) gene of the “green” dinoflagellate Gymnodinium chlorophorum and show that it is sister to Lepidodinium viride, indicating that their common ancestor obtained the prasinophyte (or other green alga) plastid in one event. As the placement of dinoflagellate species that acquired green algal or haptophyte plastids is unclear from small and large subunit (LSU) rRNA trees, we tested the usefulness of the heat shock protein (Hsp) 90 gene for dinoflagellate phylogeny by sequencing it from four species with aberrant plastids ( G. chlorophorum, Karlodinium micrum, Karenia brevis, and Karenia mikimotoi) plus Alexandrium tamarense, and constructing phylogenetic trees for Hsp90 and rRNAs, separately and together. Analyses of the Hsp90 and concatenated data suggest an ancestral origin of the peridinin-containing plastid, and two independent replacements of the peridinin plastid soon after the early radiation of the dinoflagellates. Thus, the Hsp90 gene seems to be a promising phylogenetic marker for dinoflagellate phylogeny. [ABSTRACT FROM AUTHOR]

Studies polysaccharides from three edible species of Nostoc (cyanobacteria) with different colony morphologies. Comparison of monosaccharide compositions and viscosities of polysaccharides from field colonies and suspension cultures; Isolation of excreted extracellular polymeric substances from the media in which the suspension cultures were grown; Main monosaccharides of the field colony polysaccharides from the three species.

A silicon requirement for growth is demonstrated for an alga other than a diatom. Concentrations of less than 1 μM silicate greatly decreased the growth rate of Synura petersenii Korshikov and caused morphological changes. Half of maximum growth rate (μ[submax] = 1.12 divisions/day) appeared at a concentration of only 0.23 μM silicate. Germanium dioxide inhibited growth considerably; the degree of inhibition varying from non to almost 100% depending upon both Si and Ge concentrations. The amount of silicon deposited in the external scales of S. petersenii is comparable per unit area to that of diatoms. S. petersenii is able to deplete the medium of silicate to very low levels. The feasibility of batch culture techniques for this kind of work is discussed briefly. [ABSTRACT FROM AUTHOR]

Examines the structure of extracellular polysaccharides produced by the Hindak strain of a soil Cryptomonas species. Presence of fucose, rhamnose, xylose, mannose, glucose, galactose, galacturonic acid, glucuronic acid, and traces of 3-O-methyl galactose; Degree of branching.