The Experts below are selected from a list of 12624 Experts worldwide ranked by ideXlab platform
Yun Tian - One of the best experts on this subject based on the ideXlab platform.
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cell death in a harmful Algal Bloom causing species alexandrium tamarense upon an algicidal bacterium induction
Applied Microbiology and Biotechnology, 2014Co-Authors: Huajun Zhang, Jinglin Lv, Yun Jin-peng, Xinli An, Su Zhang, Hong Xu, Yun Tian, Wei Zheng, Jun Zhang, Tianling ZhengAbstract:Harmful Algal Blooms occur throughout the world, destroying aquatic ecosystems and threatening human health. The culture supernatant of the marine algicidal bacteria DHQ25 was able to lysis dinoflagellate Alexandrium tamarense. Loss of photosynthetic pigments, accompanied by a decline in Photosystem II (PSII) photochemical efficien- cy (Fv/Fm), in A. tamarense was detected under bacterial supernatant stress. Transmission electron microscope analysis showed obvious morphological modifications of chloroplast dismantling as a part of the algicidal process. The PSII elec- tron transport chain was seriously blocked, with its reaction center damaged. This damage was detected in a relative tran- scriptional level of psb Aa ndpsbD genes, which encode the D1 and D2 proteins in the PSII reaction center. And the block in the electron transport chain of PSII might generate exces- sive reactive oxygen species (ROS) which could destroy the membrane system and pigment synthesis and activated enzy- mic antioxidant systems including superoxide dismutase (SOD) and catalase (CAT). This study indicated that marine bacteria with indirect algicidal activity played an important role in the changes of photosynthetic process in a harmful Algal Bloom species.
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a marine algicidal actinomycete and its active substance against the harmful Algal Bloom species phaeocystis globosa
Applied Microbiology and Biotechnology, 2013Co-Authors: Xiaowei Zheng, Hui Wang, Bangzhou Zhang, Jinlong Zhang, Liping Huang, Xinyi Li, Yanyan Zhou, Xiaoru Yang, Jianqiang Su, Yun TianAbstract:A strain O4-6, which had pronounced algicidal effects to the harmful Algal Bloom causing alga Phaeocystis globosa, was isolated from mangrove sediments in the Yunxiao Mangrove National Nature Reserve, Fujian, China. Based on the 16S rRNA gene sequence and morphological characteristics, the isolate was found to be phylogenetically related to the genus Streptomyces and identified as Streptomyces malaysiensis O4-6. Heat stability, pH tolerance, molecular weight range and aqueous solubility were tested to characterize the algicidal compound secreted from O4-6. Results showed that the algicidal activity of this compound was not heat stable and not affected by pH changes. Residue extracted from the supernatant of O4-6 fermentation broth by ethyl acetate, was purified by Sephadex LH-20 column and silica gel column chromatography before further structure determination. Chemical structure of the responsible compound, named NIG355, was illustrated based on quadrupole time-of-flight mass spectrometry (Q-TOF-MS) and nuclear magnetic resonance (NMR) spectra. And this compound showed a stronger algicidal activity compared with other reported algicides. Furthermore, this article represents the first report of an algicide against P. globosa, and the compound may be potentially used as a bio-agent for controlling harmful Algal Blooms.
Corina P. D. Brussaard - One of the best experts on this subject based on the ideXlab platform.
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Characterization of different viruses infecting the marine harmful Algal Bloom species Phaeocystis globosa.
Virology, 2005Co-Authors: Anne-claire Baudoux, Corina P. D. BrussaardAbstract:Abstract Twelve lytic viruses (PgV) infecting the marine unicellular eukaryotic harmful Algal Bloom species Phaeocystis globosa were isolated from the southern North Sea in 2000–2001 and partially characterized. All PgV isolates shared common phenotypic features with other Algal viruses belonging to the family Phycodnaviridae and could be categorized in four different groups. Two main groups (PgV Group I and II) were discriminated based on particle size (150 and 100 nm respectively), genome size (466 and 177 kb) and structural protein composition. The lytic cycle showed a latent period of 10 h for PgV Group I and latent periods of 12 h and 16 h for PgV Group IIA and IIB. Host specificity and temperature sensitivity finally defined a fourth group (PgV Group IIC). Our results imply that viral infection plays an important role not only in P. globosa dynamics but also in the diversity of both host and virus community.
Cynthia A Heil - One of the best experts on this subject based on the ideXlab platform.
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brevetoxicosis red tides and marine mammal mortalities
Nature, 2005Co-Authors: Leanne J Flewelling, Daniel G Baden, Jerome Naar, Jay P Abbott, Nelio B Barros, Gregory D Bossart, Marieyasmine D Bottein, Daniel G Hammond, Elsa M Haubold, Cynthia A HeilAbstract:Unexpected brevetoxin vectors may account for deaths long after or remote from an Algal Bloom.
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red tides and marine mammal mortalities
Nature, 2005Co-Authors: Leanne J Flewelling, Daniel G Baden, Jerome Naar, Jay P Abbott, Nelio B Barros, Gregory D Bossart, Marieyasmine D Bottein, Daniel G Hammond, Elsa M Haubold, Cynthia A HeilAbstract:Unexpected brevetoxin vectors may account for deaths long after or remote from an Algal Bloom.
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prorocentrum minimum pavillard schiller a review of a harmful Algal Bloom species of growing worldwide importance
Harmful Algae, 2005Co-Authors: Cynthia A Heil, Patricia M Glibert, Chunlei FanAbstract:Prorocentrum minimum (Pavillard) Schiller, a common, neritic, Bloom-forming dinoflagellate, is the cause of harmful Blooms in many estuarine and coastal environments. Among harmful Algal Bloom species, P. minimum is important for the following reasons: it is widely distributed geographically in temperate and subtropical waters; it is potentially harmful to humans via shellfish poisoning; it has detrimental effects at both the organismal and environmental levels; Blooms appear to be undergoing a geographical expansion over the past several decades; and, a relationship appears to exist between Blooms of this species and increasing coastal eutrophication. Although shellfish toxicity with associated human impacts has been attributed to P. minimum Blooms from a variety of coastal environments (Japan; France; Norway; Netherlands; New York, USA), only clones isolated from the Mediterranean coast of France, and shellfish exposed to P. minimum Blooms in this area, have been shown to contain a water soluble neurotoxic component which killed mice. Detrimental ecosystem effects associated with Blooms range from fish and zoobenthic mortalities to shellfish aquaculture mortalities, attributable to both indirect biomass effects (e.g., low dissolved oxygen) and toxic effects. P. minimum Blooms generally occur under conditions of high temperatures and incident irradiances and low to moderate salinities in coastal and estuarine environments often characterized as eutrophic, although they have been found under widely varying salinities and temperatures if other factors are conducive for growth. The physiological flexibility of P. minimum in response to changing environmental parameters (e.g., light, temperature, salinity) as well as its ability to utilize both inorganic and organic nitrogen, phosphorus, and carbon nutrient sources, suggest that increasing Blooms of this species are a response to increasing coastal eutrophication.
Jonghyeob Kim - One of the best experts on this subject based on the ideXlab platform.
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recolonization of zostera marina following destruction caused by a red tide Algal Bloom the role of new shoot recruitment from seed banks
Marine Ecology Progress Series, 2007Co-Authors: Kunseop Lee, Jungim Park, Young Kyun Kim, Sang Rul Park, Jonghyeob KimAbstract:Harmful microAlgal Blooms such as red-tide or brown-tide events lead to abrupt light reductions and consequently cause immediate damage to seagrass beds. Because red tide Algal Blooms usually occur unexpectedly, seagrass responses to the microAlgal Blooms have rarely been documented. A red tide caused by a dense Bloom of Heterosigma akashiwo, a noxious red-tide-caus- ing alga of temperate and subtropical waters, occurred at a study site on the south coast of Korea in late May 2002. Because the red-tide event occurred on an eelgrass bed where seagrass monitoring was being conducted, pre-event conditions were well documented. Nearly all eelgrass shoots disap- peared rapidly because of the reduction in light caused by the Algal Bloom. Additionally, a thick layer of mucilaginous material secreted from Algal cysts suffocated eelgrass plants for weeks, directly caus- ing eelgrass death. Eelgrass seedlings were found in the die-off area from December 2002; <1 yr after its destruction, the site was completely re-established by seedling recruitment via germination from the seed bank. Seedling mortality was very low. Seedlings grew exponentially during the spring, and their fast growth also contributed to rapid eelgrass recolonization. During the second year of recolo- nization, asexual reproduction through lateral shoot production by rhizome elongation and branch- ing played the main role in the persistence and growth of the eelgrass bed. Seed density in the seed bank varied seasonally, increasing to a maximum after seed release and decreasing to nearly zero after seed germination. Many more seedlings were found and nearly all seedlings established suc- cessfully in the first year after the Bloom, when no adult eelgrass shoots were observed, suggesting significant effects of shoot density on rates of seed germination and seedling establishment. This was a unique opportunity to examine eelgrass responses to dense microAlgal Blooms, which provided valuable information on the die-off process caused by red tide and the natural recolonization of sea- grass after its destruction.
Koki Mukai - One of the best experts on this subject based on the ideXlab platform.
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effects of light and hydrogen peroxide on gene expression of newly identified antioxidant enzymes in the harmful Algal Bloom species chattonella marina
European Journal of Phycology, 2019Co-Authors: Koki Mukai, Yohei Shimasaki, Xuchun Qiu, Mst Ruhina Margia Khanam, Yoko Katounoki, Kun Chen, Yuji OshimaAbstract:Antioxidant enzymes are essential proteins that maintain cell proliferation potential by protecting against oxidative stress. They are present in many organisms including harmful Algal Bloom (HAB) ...
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Effects of light and hydrogen peroxide on gene expression of newly identified antioxidant enzymes in the harmful Algal Bloom species Chattonella marina
2019Co-Authors: Koki Mukai, Yohei Shimasaki, Xuchun Qiu, Yoko Kato-unoki, Mst Ruhina Margia Khanam, Kun Chen, Yuji OshimaAbstract:Antioxidant enzymes are essential proteins that maintain cell proliferation potential by protecting against oxidative stress. They are present in many organisms including harmful Algal Bloom (HAB) species. We previously identified the antioxidant enzyme 2-Cys peroxiredoxin (PRX) in the raphidophyte Chattonella marina. This enzyme specifically decomposes a hydrogen peroxide (H2O2). PRX is the only antioxidant enzyme so far identified in C. marina. This study used mRNA-seq, using Trinity assemble and blastx for annotation, to identify a further five antioxidant enzymes from C. marina: Cu Zn superoxide dismutase (Cu/Zn-SOD), glutathione peroxidase (GPX), catalase (CAT), ascorbate peroxidase (APX) and thioredoxin (TRX). In the gene expression analysis of six enzymes (Cu/Zn-SOD, GPX, CAT, APX, TRX and PRX) using light-acclimated (100 μmol photons m−2 s−1) C. marina cells, only PRX gene expression levels were significantly increased by strong light irradiation (1000 μmol photons m−2 s−1). H2O2 concentration and scavenging activity were also increased and significantly positively correlated with PRX gene expression levels. In dark-acclimated cells, expression levels of all antioxidant enzymes except APX were significantly increased by light irradiation (100 μmol photons m−2 s−1). Expression decreased the following day, with the exception of PRX expression. With the exception of CAT, gene expression of antioxidant enzymes was not significantly induced by artificial H2O2 treatment, although average gene expression levels were slightly increased in some enzymes. Thus, we suggest that light is the main trigger of gene expression, but the resultant oxidative stress is also a possible factor affecting the gene expression of antioxidant enzymes in C. marina.
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Gene structure and cDNA sequence of 2-Cys peroxiredoxin in the harmful Algal Bloom species Chattonella marina and its gene transcription under different light intensities
European Journal of Phycology, 2017Co-Authors: Koki Mukai, Yohei Shimasaki, Ayano Teramoto, Xuchun Qiu, Yoko Kato-unoki, Jae Man Lee, Naohiro Mizoguchi, Mst Ruhina Margia Khanam, Hina Satone, Tsuneyuki TatsukeAbstract:ABSTRACTWe investigated the gene structure and predicted amino acid sequence of the antioxidant enzyme 2-Cys peroxiredoxin (2-Cys Prx) in the raphidophyte Chattonella marina, which is a harmful Algal Bloom (HAB) species. The open reading frame of 2-Cys Prx was 585 bp long and encoded a protein consisting of 195 amino acids. The putative amino acid sequence contained two cysteine residues located at the 49th and 170th amino acid positions from the N-terminal methionine residue. The sequence also possessed 2-Cys Prx characteristic motifs, F (FFYPLDFTFVCPTEI) and EVCP. The position of the 2-Cys Prx gene relative to several others (ycf59 – 2-CysPrx – rpl35 – rpl20) was the same as that found in the chloroplast genome in the raphidophyte Heterosigma akashiwo. Upstream of the 2-Cys Prx gene, possible TATA and GGA motifs recognized by nuclear-encoded plastid RNA polymerase (NEP), and a possible -10 box and -35 box recognized by plastid-encoded plastid RNA polymerase (PEP) were observed. We measured the transcrip...
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Gene structure and cDNA sequence of 2-Cys peroxiredoxin in the harmful Algal Bloom species Chattonella marina and its gene transcription under different light intensities
2017Co-Authors: Koki Mukai, Yohei Shimasaki, Ayano Teramoto, Xuchun Qiu, Yoko Kato-unoki, Jae Man Lee, Naohiro Mizoguchi, Mst Ruhina Margia Khanam, Hina Satone, Tsuneyuki TatsukeAbstract:We investigated the gene structure and predicted amino acid sequence of the antioxidant enzyme 2-Cys peroxiredoxin (2-Cys Prx) in the raphidophyte Chattonella marina, which is a harmful Algal Bloom (HAB) species. The open reading frame of 2-Cys Prx was 585 bp long and encoded a protein consisting of 195 amino acids. The putative amino acid sequence contained two cysteine residues located at the 49th and 170th amino acid positions from the N-terminal methionine residue. The sequence also possessed 2-Cys Prx characteristic motifs, F (FFYPLDFTFVCPTEI) and EVCP. The position of the 2-Cys Prx gene relative to several others (ycf59 – 2-CysPrx – rpl35 – rpl20) was the same as that found in the chloroplast genome in the raphidophyte Heterosigma akashiwo. Upstream of the 2-Cys Prx gene, possible TATA and GGA motifs recognized by nuclear-encoded plastid RNA polymerase (NEP), and a possible -10 box and -35 box recognized by plastid-encoded plastid RNA polymerase (PEP) were observed. We measured the transcript levels of 2-Cys Prx in C. marina cells grown under three different light intensities (0, 100, 1000 µmol photons m–2 s–1, 14-h light/8-h dark photoperiod) by quantitative PCR. The 2-Cys Prx transcript level in cells grown under the highest light intensity on day 3 was threefold that on day 0 but two lower light intensities resulted in relatively stable transcription levels. The 2-Cys Prx transcript level was significantly positively related to the H2O2 concentration per cell and the H2O2 scavenging activity per cell. These results suggest that C. marina 2-Cys Prx functions in the chloroplast and its transcription could be regulated by both NEP and PEP. Moreover, the 2-Cys Prx transcript level might increase to remove excessive H2O2 produced under strong light conditions in order to maintain cell proliferation activity.