The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
David A. Caron - One of the best experts on this subject based on the ideXlab platform.
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Effects of temperature on growth rate and gross growth efficiency of an Antarctic bacterivorous protist
The ISME Journal, 2009Co-Authors: Julie M Rose, Neil M Vora, Peter D Countway, Rebecca J Gast, David A. CaronAbstract:The effects of temperature on the growth rate and gross growth efficiency (GGE) of the heterotrophic nanoflagellate, Paraphysomonas imperforata , cultured from the Ross Sea, Antarctica were investigated using five experimental temperatures (range=0–20 °C). This bacterivorous protist exhibited measurable growth over the temperature range examined, although temperature exerted a significant effect on its growth rate. There was no evidence for an effect of temperature on GGE. The growth rates and GGE of our Antarctic P. imperforata isolate were compared to values reported for other cultures of species from this genus. A wide range of growth efficiencies have been reported for different strains of Paraphysomonas spp., but our estimates were comparable to mean/median values reported in the literature. The growth rates of our Antarctic P. imperforata were similar to rates obtained for an Arctic conspecific at low temperatures (0–5 °C), among the highest reported rates for any Paraphysomonas species at intermediate temperatures (10–15 °C) and similar to rates reported for temperate congeners and conspecifics at 20 °C. Q _10 values of 15, 2.2, 3.6 and 0.93 were calculated for growth rates at 5 °C intervals between 0 and 20 °C, respectively. Results indicated that our Antarctic P. imperforata grew at rates comparable to other polar isolates at ambient polar temperatures, but these low temperatures may be outside the physiological optimum for the isolate.
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Effects of temperature on growth rate and gross growth efficiency of an Antarctic bacterivorous protist.
The ISME journal, 2008Co-Authors: Julie M Rose, Neil M Vora, Peter D Countway, Rebecca J Gast, David A. CaronAbstract:The effects of temperature on the growth rate and gross growth efficiency (GGE) of the heterotrophic nanoflagellate, Paraphysomonas imperforata, cultured from the Ross Sea, Antarctica were investigated using five experimental temperatures (range=0-20 degrees C). This bacterivorous protist exhibited measurable growth over the temperature range examined, although temperature exerted a significant effect on its growth rate. There was no evidence for an effect of temperature on GGE. The growth rates and GGE of our Antarctic P. imperforata isolate were compared to values reported for other cultures of species from this genus. A wide range of growth efficiencies have been reported for different strains of Paraphysomonas spp., but our estimates were comparable to mean/median values reported in the literature. The growth rates of our Antarctic P. imperforata were similar to rates obtained for an Arctic conspecific at low temperatures (0-5 degrees C), among the highest reported rates for any Paraphysomonas species at intermediate temperatures (10-15 degrees C) and similar to rates reported for temperate congeners and conspecifics at 20 degrees C. Q(10) values of 15, 2.2, 3.6 and 0.93 were calculated for growth rates at 5 degrees C intervals between 0 and 20 degrees C, respectively. Results indicated that our Antarctic P. imperforata grew at rates comparable to other polar isolates at ambient polar temperatures, but these low temperatures may be outside the physiological optimum for the isolate.
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Identification of heterotrophic nanoflagellates by restriction fragment length polymorphism analysis of small subunit ribosomal DNA.
The Journal of eukaryotic microbiology, 2001Co-Authors: Ee Lin Lim, Mark R. Dennett, David A. CaronAbstract:Thirty clones derived from twenty isolates of heterotrophic nanoflagellates originating from a variety of marine and freshwater environments were examined by restriction fragment length polymorphism analysis of small subunit ribosomal RNA genes amplified by the polymerase chain reaction (riboprinting). The data were compared with light and electron microscopical identification of the isolates. On morphological criteria, sixteen of the thirty clones belonged to the genus Paraphysomonas De Saedeleer, seven to the genus Spumella Cienkowski, four to the genus Pteridomonas Penard and three to the genus Cafeteria Fenchel and Patterson. Among these taxa, eleven ribotypes were detected by analysis with the restriction enzymes Hinf I, Hae III, Sau3A I, and Msp I. Differentiation of nanoflagellate taxa by the riboprinting method supported taxonomic classification based on morphology at the generic and species level. The utility of the method for discriminating the 'naked' flagellates and for confirming the identity of polymorphic forms among species of Paraphysomonas is demonstrated.
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MOLECULAR PHYLOGENETIC ANALYSIS OF THE HETEROTROPHIC CHRYSOPHYTE GENUS Paraphysomonas (CHRYSOPHYCEAE), AND THE DESIGN OF RRNA-TARGETED OLIGONUCLEOTIDE PROBES FOR TWO SPECIES
Journal of Phycology, 1999Co-Authors: David A. Caron, Mark R. Dennett, Rebecca J Gast, Ee Lin Lim, Carol Kosman, Edward F. DelongAbstract:Nanoflagellate protists are algae and protozoa (2‐ 20 mm in size) that play important ecological roles in freshwater and marine microbial communities as primary producers and as consumers of prokaryotic and eukaryotic prey. There is little biogeographical information for most of these minute protists despite their significant role in aquatic food webs. In addition, the evolutionary relationships among some of these species and their affinities to other protistan taxa are unclear. These circumstances are largely a consequence of the fact that small protists possess few readily apparent morphological features on which to base taxonomic and phylogenetic schemes and with which to identify them in natural assemblages. As an alternative approach for addressing these issues, we sequenced the small-subunit ribosomal RNA genes of four species of the colorless chrysophyte genus Paraphysomonas. A phylogenetic analysis based on that sequence information was performed, and oligonucleotide probes for two commonly occurring species of Paraphysomonas were designed and tested. Phylogenetic analyses of these four species confirmed the affinity of the genus Paraphysomonas with other chrysophyte species. High sequence similarity among three of the species (P. imperforata Lucas, P. bandaiensis Takahashi, and P. foraminifera Lucas) supported a previous phylogenetic grouping of these species based on the morphology of the scales produced by these species. In particular, sequence similarity between P. imperforata and P. foraminifera indicated that this speciation was a recent evolutionary event. However, a fourth species (P. vestita (Stokes) de Saedeleer) possessing similar scale morphology to P. bandaiensis, P. imperforata, and P. foraminifera showed considerable sequence dissimilarity in comparison to these latter three species. Oligonucleotide probes were successfully designed for the species P. imperforata and P. bandaiensis and applied together with a recently de
Koenraad Muylaert - One of the best experts on this subject based on the ideXlab platform.
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low doses of the quaternary ammonium salt cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Bert Deruyck, Thi Kim Hue Nguyen, Ramasamy Praveenkumar, Koenraad MuylaertAbstract:Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p < 0.05) in microalgal productivity. However, doses exceeding 5 μM also negatively affected microalgal growth. The optimal dose of CTAB that resulted in complete eradication of the grazers with minimum impact on microalgal productivity was 3 μM for Brachionus, 2 μM for Sterkiella and 3 μM for Paraphysomonas. Thus, being a readily available chemical, CTAB has the potential to be used as a fast-acting, low-cost control agent against a range of frequently occurring grazer types in large-scale microalgal cultures.
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Low doses of the quaternary ammonium salt Cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
Algal Research, 2019Co-Authors: Bert Deruyck, Thi Kim Hue Nguyen, Ramasamy Praveenkumar, Koenraad MuylaertAbstract:Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p
Thi Kim Hue Nguyen - One of the best experts on this subject based on the ideXlab platform.
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low doses of the quaternary ammonium salt cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Bert Deruyck, Thi Kim Hue Nguyen, Ramasamy Praveenkumar, Koenraad MuylaertAbstract:Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p < 0.05) in microalgal productivity. However, doses exceeding 5 μM also negatively affected microalgal growth. The optimal dose of CTAB that resulted in complete eradication of the grazers with minimum impact on microalgal productivity was 3 μM for Brachionus, 2 μM for Sterkiella and 3 μM for Paraphysomonas. Thus, being a readily available chemical, CTAB has the potential to be used as a fast-acting, low-cost control agent against a range of frequently occurring grazer types in large-scale microalgal cultures.
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Low doses of the quaternary ammonium salt Cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
'Elsevier BV', 2019Co-Authors: Deruyck Bert, Thi Kim Hue Nguyen, Praveenkumar Ramasamy, Muylaert KoenraadAbstract:© 2019 Elsevier B.V. Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p < 0.05) in microalgal productivity. However, doses exceeding 5 μM also negatively affected microalgal growth. The optimal dose of CTAB that resulted in complete eradication of the grazers with minimum impact on microalgal productivity was 3 μM for Brachionus, 2 μM for Sterkiella and 3 μM for Paraphysomonas. Thus, being a readily available chemical, CTAB has the potential to be used as a fast-acting, low-cost control agent against a range of frequently occurring grazer types in large-scale microalgal cultures.status: publishe
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Low doses of the quaternary ammonium salt Cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
Algal Research, 2019Co-Authors: Bert Deruyck, Thi Kim Hue Nguyen, Ramasamy Praveenkumar, Koenraad MuylaertAbstract:Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p
Ramasamy Praveenkumar - One of the best experts on this subject based on the ideXlab platform.
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low doses of the quaternary ammonium salt cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Bert Deruyck, Thi Kim Hue Nguyen, Ramasamy Praveenkumar, Koenraad MuylaertAbstract:Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p < 0.05) in microalgal productivity. However, doses exceeding 5 μM also negatively affected microalgal growth. The optimal dose of CTAB that resulted in complete eradication of the grazers with minimum impact on microalgal productivity was 3 μM for Brachionus, 2 μM for Sterkiella and 3 μM for Paraphysomonas. Thus, being a readily available chemical, CTAB has the potential to be used as a fast-acting, low-cost control agent against a range of frequently occurring grazer types in large-scale microalgal cultures.
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Low doses of the quaternary ammonium salt Cetyltrimethylammonium bromide can be used as a pesticide to control grazers in microalgal cultures
Algal Research, 2019Co-Authors: Bert Deruyck, Thi Kim Hue Nguyen, Ramasamy Praveenkumar, Koenraad MuylaertAbstract:Contamination of large-scale microalgal cultures by grazers can cause huge losses in biomass productivity. Here we propose the use of a quaternary ammonium salt cetyltrimethylammonium bromide (CTAB) to eradicate three types of commonly occurring grazers in microalgal cultures: the rotifer Brachionus, the ciliate Sterkiella and the flagellate Paraphysomonas. Low, premicellar doses (≤3 μM) of CTAB rapidly eradicated (within 1–2 d) all three tested grazers from microalgal cultures without significant losses (p
Erik Von Alert - One of the best experts on this subject based on the ideXlab platform.
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Fatty acid composition of the heterotrophic nanoflagellate Paraphysomonas sp. : influence of diet and de novo synthesis
Aquatic Biology, 2010Co-Authors: Alexandre Bec, Dominik Martin-creuzburg, Erik Von AlertAbstract:We compared the relative importance of dietary factors versus de novo synthesis in determining the polyunsaturated fatty acid (PUFA) composition of the heterotrophic nanoflagellate Paraphysomonas sp. The flagellate was fed with different mutants of the picocyanobacterial strain Synechocystis PCC6803, which differ in their capability to synthesize specific PUFAs. The desA, desB, and desD genes of Synechocystis PCC6803 encode lipid desaturases at the Δ12, Δ15, and Δ6 positions of 18C fatty acids (FAs), respectively. Thus, the use of desA–, desB–, desD–, and desA–/des D– mutants of Synechocystis PCC6803 as food sources permitted us to provide the heterotrophic flagellate with decreasing levels of unsaturated FAs. In each treatment, Paraphysomonas sp. exhibited the same FA composition pattern, i.e. high levels of 16:0 and 18:1, and significant amounts of 18C PUFAs and long-chain PUFAs such as 20:4(n-6), 20:5(n-3), and 22:6(n-3), which indicated that Paraphysomonas sp. is capable of synthesizing these PUFAs de novo. Results also showed that dietary 18C PUFAs seem to be preferentially accumulated in Paraphysomonas sp. lipids. This demonstrates that heterotrophic protists could play a key role in transferring essential compounds from primary producers to metazoan consumers.
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Trophic upgrading of autotrophic picoplankton by the heterotrophic nanoflagellate Paraphysomonas sp
Limnology and Oceanography, 2006Co-Authors: Alexandre Bec, Dominik Martin-creuzburg, Erik Von AlertAbstract:We investigated whether trophic repackaging of autotrophic picoplankton by phagotrophic protists is associated with an improvement in food quality for the metazooplankton Daphnia magna (i.e., whether trophic upgrading occurs in this system). The nutritional value of the autotrophic species Microcystis aeruginosa PCC7806, Synechococcus sp. strain BO8809, Synechococcus elongatus SAG 89.79, and Choricystis minor KR1988/ 8, and of the heterotrophic nanoflagellate Paraphysomonas sp. grown on these different picoplanktonic species was evaluated in standardized growth experiments with D. magna. In order to investigate the functional role of the flagellate in the simplified autotrophic picoplankton-Daphnia food chain, Paraphysomonas sp. was grown on the different picoplanktonic organisms and subsequently separated from the food items before being fed to D. magna. The presence of Paraphysomonas sp. as an intermediary trophic step enhanced somatic growth and reproduction of D. magna. Supplementation of Synechococcus sp. with lipids from Paraphysomonas sp. (grown on Synechococcus sp.) revealed that trophic upgrading of autotrophic picoplankton is due to the additional lipids present in the flagellate. Paraphysomonas sp. synthesized polyunsaturated fatty acids and sterols de novo, which most likely explains the trophic upgrading. Paraphysomonas sp. also improved the food quality of M. aeruginosa PCC7806, which is toxic for D. magna. The heterotrophic flagellate Paraphysomonas sp. is capable of trophically upgrading a poor quality food source not only by producing essential lipids, but also by detoxifying the cyanobacterial food organism.
