Diatom silicon biomineralization as an inspirational source of new approaches to silica production

The demand for new materials and products is still growing and the interest in naturally formed biopolymers and biominerals, such as chitin, calcium precipitates and silica is increasing. Photosynthesizing microalgae of the family Bacillariophyceae (diatoms) produce silica exoskeletons with a potential to be used in specific industrial or technological processes, they also are an excellent model in studies of silicon biomineralization. In contrast to geologically aged diatomaceous earth, the freshly prepared silica of cultured or harvested natural diatoms has been characterized insufficiently with respect to the properties (e.g. purity, specific surface area, porosity) required for technological and industrial application. In this contribution we summarize aspects of cellular processes that are involved in silicon biomineralization of diatoms and the current knowledge of the characterization of diatomaceous silica, following methods used for synthetically derived silica-based materials

Temporal and spatial distribution of the ichthyotoxic dinoflagellate Gyrodinium aureolum Hulburt in the St Lawrence, Canada

The occurrence of the potentially ichthyotoxic dinoflagellate Gyrodinium aureolum Hulburt is reported for the first time in the Lower Estuary and Gulf of St Lawrence. Taxonomic identification using an immunochemical tagging method suggests a close taxonomic proximity between the species found in the St Lawrence and G. aureolum present in European waters In 1993, G. aureolum was observed along the entire coast of Quebec and in offshore waters of the Gulf of St Lawrence. At the coastal stations, G. aureolum showed large week-to-week variations, but higher densities were observed during late August and early September. Bloom concentrations (10(6) cells l(-1)) were only observed in the Gaspe Current at Mont-Louis, on the north coast of the Gaspe peninsula. In the central part of the Gulf, G. aureolum was concentrated in the upper 5 m of the stations directly influenced by the freshwater run-off of the St Lawrence Estuary. Results from principal component analysis indicate that G. aureolum favors environments with high nitrogen recycling activity

Expression and targeting of a 47 kDa integral peroxisomal membrane protein of Candida boidinii in wild type and a peroxisome-deficient mutant of Hansenula polymorpha

A 47 kDa integral peroxisomal membrane protein (PMP47) of Candida boidinii was expressed in wild type (WT) and a temperature-sensitive (Ts6) peroxisome-deficient (per) mutant of Hansenula polymorpha. The subcellular location of PMP47 appeared to be dependent on the level of expression. At low expression levels PMP47 was sorted to the peroxisomal membrane; however, in Ts6 cells grown at restrictive temperatures (which lack intact peroxisomes) PMP47 was solely located in small cytosolic aggregates, together with homologous H. polymorpha PMP’s. At enhanced expression levels, however, part of the protein also became incorporated into mitochondria, both in transformed WT and Ts6 cells.