The Experts below are selected from a list of 41829 Experts worldwide ranked by ideXlab platform
Tadashi Matsunaga - One of the best experts on this subject based on the ideXlab platform.
-
effect of ultraviolet a uv a light on growth Photosynthetic Activity and production of biopterin glucoside by the marine uv a resistant cyanobacterium oscillatoria sp
Biochimica et Biophysica Acta, 1995Co-Authors: Youji Wachi, Grant J Burgess, Kaori Iwamoto, Noriko Yamada, Noriyuki Nakamura, Tadashi MatsunagaAbstract:We have isolated a marine planktonic cyanobacterium Oscillatoria sp. NKBG 091600 which is resistant to ultraviolet-A (UV-A) irradiation. In response to UV-A irradiation this cyanobacterium produces high levels of a UV-A absorbing compound which was identified previously as biopterin glucoside. Here, we have investigated the effect of UV-A light intensity on growth, biopterin glucoside production and Photosynthetic Activity. Oscillatoria sp. NKBG 091600 could grow at UV-A intensities of up to 800 microW/cm2 and at 300 microW/cm2 could grow as well as in the absence of UV-A irradiation. In addition, pre-culture of cells with UV-A protected cells from UV-A induced inhibition of Photosynthetic Activity. Detection of biopterin glucoside levels in irradiated cells by HPLC demonstrated that after 10 h there was a rapid increase in biopterin glucoside content. This increase was dependent on the intensity on the intensity of the UV-A irradiation.
-
effect of ultraviolet a uv a light on growth Photosynthetic Activity and production of biopterin glucoside by the marine uv a resistant cyanobacterium oscillatoria sp
Biochimica et Biophysica Acta, 1995Co-Authors: Youji Wachi, Grant J Burgess, Kaori Iwamoto, Noriko Yamada, Noriyuki Nakamura, Tadashi MatsunagaAbstract:Abstract We have isolated a marine planktonic cyanobacterium Oscillatoria sp. NKBG 091600 which is resistant to ultraviolet-A (UV-A) irradiation. In response to UV-A irradiation this cyanobacterium produces high levels of a UV-A absorbing compound which was identified previously as biopterin glucoside. Here, we have investigated the effect of UV-A light intensity on growth, biopterin glucoside production and Photosynthetic Activity. Oscillatoria sp. NKBG 091600 could grow at UV-A intensities of up to 800 μW/cm2 and at 300 μW/cm2 could grow as well as in the absence of UV-A irradiation. In addition, pre-culture of cells with UV-A protected cells from UV-A induced inhibition of Photosynthetic Activity. Detection of biopterin glucoside levels in irradiated cells by HPLC demonstrated that after 10 h there was a rapid increase in biopterin glucoside content. This increase was dependent on the intensity of the UV-A irradiation.
Douglas Couet - One of the best experts on this subject based on the ideXlab platform.
-
effects of copper and butyltin compounds on the growth Photosynthetic Activity and toxin production of two hab dinoflagellates the planktonic alexandrium catenella and the benthic ostreopsis cf ovata
Aquatic Toxicology, 2018Co-Authors: Douglas Couet, Chrystelle Banconmontigny, Nicolas Briant, Francoise Elbaz Poulichet, Sophie Delpoux, Ons Kefidaly Yahia, Bengharbia Hela, Olivier Pringault, Mrabet CharafAbstract:Abstract Controlled laboratory experiments were conducted to test the effects of copper (Cu 2+ ) and butyltins (BuT) on the growth, Photosynthetic Activity and toxin content of two HABs (Harmful Algal Blooms) dinoflagellates, the planktonic Alexandrium catenella and the benthic Ostreopsis cf. ovata . Microalgae were exposed to increasing concentrations of Cu 2+ (10 −4 to 31 nM) or BuT (0.084 to 84 nM) for seven days. When considering the growth, EC 50 values were 0.16 (±0.09) nM and 0.03 (±0.02) nM of Cu 2+ for A. catenella and O. cf. ovata , respectively. Regarding BuT, EC 50 was 14.2 (±6) nM for O. cf. ovata , while A. catenella growth inhibition appeared at BuT concentrations ≥27 nM. Photosynthetic Activity of the studied dinoflagellates decreased with increasing Cu and BuT concentrations. For O. cf. ovata , the response of this physiological parameter to contamination was less sensitive than the biomass. Cu exposure induced the formation of temporary cysts in both organisms that could resist adverse conditions. The ovatoxin-a and -b concentrations in O. cf. ovata cells increased significantly in the presence of Cu. Altogether, the results suggest a better tolerance of the planktonic A. catenella to Cu and BuT. This could result in a differentiated selection pressure exerted by these metals on phytoplankton species in highly polluted waters. The over-production of toxins in response to Cu stress could pose supplementary health and socio-economic threats in the contaminated marine ecosystems where HABs develop.
Youji Wachi - One of the best experts on this subject based on the ideXlab platform.
-
effect of ultraviolet a uv a light on growth Photosynthetic Activity and production of biopterin glucoside by the marine uv a resistant cyanobacterium oscillatoria sp
Biochimica et Biophysica Acta, 1995Co-Authors: Youji Wachi, Grant J Burgess, Kaori Iwamoto, Noriko Yamada, Noriyuki Nakamura, Tadashi MatsunagaAbstract:We have isolated a marine planktonic cyanobacterium Oscillatoria sp. NKBG 091600 which is resistant to ultraviolet-A (UV-A) irradiation. In response to UV-A irradiation this cyanobacterium produces high levels of a UV-A absorbing compound which was identified previously as biopterin glucoside. Here, we have investigated the effect of UV-A light intensity on growth, biopterin glucoside production and Photosynthetic Activity. Oscillatoria sp. NKBG 091600 could grow at UV-A intensities of up to 800 microW/cm2 and at 300 microW/cm2 could grow as well as in the absence of UV-A irradiation. In addition, pre-culture of cells with UV-A protected cells from UV-A induced inhibition of Photosynthetic Activity. Detection of biopterin glucoside levels in irradiated cells by HPLC demonstrated that after 10 h there was a rapid increase in biopterin glucoside content. This increase was dependent on the intensity on the intensity of the UV-A irradiation.
-
effect of ultraviolet a uv a light on growth Photosynthetic Activity and production of biopterin glucoside by the marine uv a resistant cyanobacterium oscillatoria sp
Biochimica et Biophysica Acta, 1995Co-Authors: Youji Wachi, Grant J Burgess, Kaori Iwamoto, Noriko Yamada, Noriyuki Nakamura, Tadashi MatsunagaAbstract:Abstract We have isolated a marine planktonic cyanobacterium Oscillatoria sp. NKBG 091600 which is resistant to ultraviolet-A (UV-A) irradiation. In response to UV-A irradiation this cyanobacterium produces high levels of a UV-A absorbing compound which was identified previously as biopterin glucoside. Here, we have investigated the effect of UV-A light intensity on growth, biopterin glucoside production and Photosynthetic Activity. Oscillatoria sp. NKBG 091600 could grow at UV-A intensities of up to 800 μW/cm2 and at 300 μW/cm2 could grow as well as in the absence of UV-A irradiation. In addition, pre-culture of cells with UV-A protected cells from UV-A induced inhibition of Photosynthetic Activity. Detection of biopterin glucoside levels in irradiated cells by HPLC demonstrated that after 10 h there was a rapid increase in biopterin glucoside content. This increase was dependent on the intensity of the UV-A irradiation.
Mrabet Charaf - One of the best experts on this subject based on the ideXlab platform.
-
effects of copper and butyltin compounds on the growth Photosynthetic Activity and toxin production of two hab dinoflagellates the planktonic alexandrium catenella and the benthic ostreopsis cf ovata
Aquatic Toxicology, 2018Co-Authors: Douglas Couet, Chrystelle Banconmontigny, Nicolas Briant, Francoise Elbaz Poulichet, Sophie Delpoux, Ons Kefidaly Yahia, Bengharbia Hela, Olivier Pringault, Mrabet CharafAbstract:Abstract Controlled laboratory experiments were conducted to test the effects of copper (Cu 2+ ) and butyltins (BuT) on the growth, Photosynthetic Activity and toxin content of two HABs (Harmful Algal Blooms) dinoflagellates, the planktonic Alexandrium catenella and the benthic Ostreopsis cf. ovata . Microalgae were exposed to increasing concentrations of Cu 2+ (10 −4 to 31 nM) or BuT (0.084 to 84 nM) for seven days. When considering the growth, EC 50 values were 0.16 (±0.09) nM and 0.03 (±0.02) nM of Cu 2+ for A. catenella and O. cf. ovata , respectively. Regarding BuT, EC 50 was 14.2 (±6) nM for O. cf. ovata , while A. catenella growth inhibition appeared at BuT concentrations ≥27 nM. Photosynthetic Activity of the studied dinoflagellates decreased with increasing Cu and BuT concentrations. For O. cf. ovata , the response of this physiological parameter to contamination was less sensitive than the biomass. Cu exposure induced the formation of temporary cysts in both organisms that could resist adverse conditions. The ovatoxin-a and -b concentrations in O. cf. ovata cells increased significantly in the presence of Cu. Altogether, the results suggest a better tolerance of the planktonic A. catenella to Cu and BuT. This could result in a differentiated selection pressure exerted by these metals on phytoplankton species in highly polluted waters. The over-production of toxins in response to Cu stress could pose supplementary health and socio-economic threats in the contaminated marine ecosystems where HABs develop.
Arturo Elosegi - One of the best experts on this subject based on the ideXlab platform.
-
effects of sediment deposition on periphytic biomass Photosynthetic Activity and algal community structure
Science of The Total Environment, 2009Co-Authors: Oihana Izagirre, Alexandra Serra, Helena Guasch, Arturo ElosegiAbstract:Abstract Suspended solids and siltation are among the most prevalent problems in streams and rivers of the world; however, because they are often associated with other stresses such as increased nutrient concentrations or changes in channel form, their impacts on the biota and on ecosystem functioning are not fully understood. To assess the effects of pulse sediment deposition on periphyton, we applied an exponential gradient of clay concentration (from 0 to 54.7 g L − 1 ) for three days to eleven artificial indoor channels precolonized by algae (three controls + eight treatments). This resulted in a gradient of inorganic particulate matter in the bottom from two to over 200 g m − 2 . Periphytic biomass, Photosynthetic Activity and algal communities were studied during the following four weeks. High sediment loads (> 6 g L − 1 ) initially reduced algal growth but by the end of the experiment periphytic biomass was similar in all channels. Under high sediment load, algal Photosynthetic efficiency showed a quick decrease after three days of exposure, followed by a delayed increase in chlorophyll a contents. After two weeks signs of adaptation were observed, first as an increase in Photosynthetic efficiency and then as an increase in pigment concentration. Siltation led to changes in community structure; diatoms increased in high silt treatments although green algae still dominated. Overall, the accumulation of fine sediment affected periphytic biomass, Photosynthetic Activity and community composition. Periphyton adaptation reduced the initial impact, reaching almost full compensation in terms of chlorophyll a and Photosynthetic Activity; however, algal community composition did not recover within the time frame of this study. Thus, the frequent siltation pulses observed in many streams throughout the world may have an important impact on the periphyton, which would in turn affect stream ecosystem structure and functioning.