scholarly journals Biosynthesis of the neurotoxin domoic acid in a bloom-forming diatom

Science ◽  
2018 ◽  
Vol 361 (6409) ◽  
pp. 1356-1358 ◽  
Author(s):  
John K. Brunson ◽  
Shaun M. K. McKinnie ◽  
Jonathan R. Chekan ◽  
John P. McCrow ◽  
Zachary D. Miles ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Gene Cluster ◽  
Molecular Basis ◽  
Harmful Algal Blooms ◽  
Transcriptome Sequencing ◽  
Algal Blooms ◽  
Domoic Acid ◽  
Genetic Basis ◽  
Toxin Production ◽  
Growth Conditions

Oceanic harmful algal blooms of Pseudo-nitzschia diatoms produce the potent mammalian neurotoxin domoic acid (DA). Despite decades of research, the molecular basis for its biosynthesis is not known. By using growth conditions known to induce DA production in Pseudo-nitzschia multiseries, we implemented transcriptome sequencing in order to identify DA biosynthesis genes that colocalize in a genomic four-gene cluster. We biochemically investigated the recombinant DA biosynthetic enzymes and linked their mechanisms to the construction of DA’s diagnostic pyrrolidine skeleton, establishing a model for DA biosynthesis. Knowledge of the genetic basis for toxin production provides an orthogonal approach to bloom monitoring and enables study of environmental factors that drive oceanic DA production.

Pathology of Domoic Acid Toxicity in California Sea Lions (Zalophus californianus)

2005 ◽  
Vol 42 (2) ◽  
pp. 184-191 ◽  
Author(s):  
P. A. Silvagni ◽  
L. J. Lowenstine ◽  
T. Spraker ◽  
T. P. Lipscomb ◽  
F. M. D. Gulland
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Domoic Acid ◽  
Pyramidal Cells ◽  
Granular Cell ◽  
Zalophus Californianus ◽  
California Sea Lions ◽  
Neuronal Necrosis ◽  
Hydropic Degeneration ◽  
Sea Lions

Over 100 free-ranging adult California sea lions ( Zalophus californianus) and one Northern fur seal ( Callorhinus ursinus), predominantly adult females, were intoxicated by domoic acid (DA) during three harmful algal blooms between 1998 and 2000 in central and northern California coastal waters. The vector prey item was Northern anchovy ( Engraulis mordax) and the primary DA-producing algal diatom was Psuedonitzschia australis. Postmortem examination revealed gross and histologic findings that were distinctive and aided in diagnosis. A total of 109 sea lions were examined, dying between 1 day and 10 months after admission to a marine mammal rehabilitation center. Persistent seizures with obtundation were the main clinical findings. Frequent gross findings in animals dying acutely consisted of piriform lobe malacia, myocardial pallor, bronchopneumonia, and complications related to pregnancy. Gross findings in animals dying months after intoxication included bilateral hippocampal atrophy. Histologic observations implicated limbic system seizure injury consistent with excitotoxin exposure. Peracutely, there was microvesicular hydropic degeneration within the neuropil of the hippocampus, amygdala, pyriform lobe, and other limbic structures. Acutely, there was ischemic neuronal necrosis, particularly apparent in the granular cells of the dentate gyrus and the pyramidal cells within the hippocampus cornu ammonis (CA) sectors CA4, CA3, and CA1. Dentate granular cell necrosis has not been reported in human or experimental animal DA toxicity and may be unique to sea lions. Chronically, there was gliosis, mild nonsuppurative inflammation, and loss of laminar organization in affected areas.

scholarly journals Understanding the Differences in the Growth and Toxin Production of Anatoxin-Producing Cuspidothrix issatschenkoi Cultured with Inorganic and Organic N Sources from a New Perspective: Carbon/Nitrogen Metabolic Balance

Toxins ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 724
Author(s):  
Siyi Tao ◽  
Suqin Wang ◽  
Lirong Song ◽  
Nanqin Gan
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Nitrogen Sources ◽  
Dry Weight ◽  
Toxin Production ◽  
Organic N ◽  
Control Group ◽  
Metabolic Balance ◽  
N Sources ◽  
Inorganic And Organic

Cyanotoxins are the underlying cause of the threat that globally pervasive Cyanobacteria Harmful algal blooms (CyanoHABs) pose to humans. Major attention has been focused on the cyanobacterial hepatotoxin microcystins (MCs); however, there is a dearth of studies on cyanobacterial neurotoxin anatoxins. In this study, we explored how an anatoxin-producing Cuspidothrix issatschenkoi strain responded to culture with inorganic and organic nitrogen sources in terms of growth and anatoxins production. The results of our study revealed that ʟ- alanine could greatly boost cell growth, and was associated with the highest cell productivity, while urea significantly stimulated anatoxin production with the maximum anatoxin yield reaching 25.86 μg/mg dry weight, which was 1.56-fold higher than that in the control group (BG11). To further understand whether the carbon/nitrogen balance in C. issatschenkoi would affect anatoxin production, we explored growth and toxin production in response to different carbon/nitrogen ratios (C/N). Anatoxin production was mildly promoted when the C/N ratio was within low range, and significantly inhibited when the C/N ratio was within high range, showing approximately a three-fold difference. Furthermore, the transcriptional profile revealed that anaC gene expression was significantly up-regulated over 2–24 h when the C/N ratio was increased, and was significantly down-regulated after 96 h. Overall, our results further enriched the evidence that urea can stimulate cyanotoxin production, and ʟ-alanine could boost C. issatschenkoi proliferation, thus providing information for better management of aquatic systems. Moreover, by focusing on the intracellular C/N metabolic balance, this study explained the anatoxin production dynamics in C. issatschenkoi in response to different N sources.

Viewpoints of Dominant Environmental Factors Influencing Algal Blooms

2011 ◽  
Vol 66-68 ◽  
pp. 155-159
Author(s):  
Di Guan ◽  
Da Wen Gao ◽  
Nan Qi Ren ◽  
Yi Fan Li
Keyword(s):  
Environmental Factors ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Meteorological Factors ◽  
Chlorophyll Concentration ◽  
Phytoplankton Growth ◽  
High Biomass ◽  
Coupling Effects ◽  
Factors Influencing

Harmful algal blooms (HABs) are generally known as excessive phytoplankton growth or rapidly concentrate to high biomass. This study summarized the situation of HABs in China, and discussed possible dominant factors stimulating algal blooms by analyzing several actual HABs cases. It was manifested nutrients may affect algae concentration principally, but such impact tended to decease with degradation of background water. Meanwhile the hydrological and meteorological factors expressed greater correlation to chlorophyll concentration under multiple coupling effects of complex environmental factors. For the complex mechanisms, the determination of principle factors which stimulate excessive algal blooms effectively still need further researches, which are suggested to conduct under overall considerations on 3 scales: macro dimension, medium dimension and micro dimension.

Influence of non-nutrient environmental factors on Ulva pertusa's inhibitory effects on Heterosigma akashiwo growth

2015 ◽  
Vol 96 (5) ◽  
pp. 1041-1052
Author(s):  
Qiu Jin ◽  
Han-Gui Wu ◽  
Xin-Xin Zhang ◽  
Zhong-Lu Ke
Keyword(s):  
Environmental Factors ◽  
Growth Inhibition ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Optimal Growth ◽  
High Irradiance ◽  
Heterosigma Akashiwo ◽  
Inhibitory Influence ◽  
Single Factor ◽  
Green Macroalgae

We studied the effects of four non-nutrient environmental factors (temperature, salinity, irradiance and pH) on the growth inhibition of the macroalgae Ulva pertusa (Chlorophyta) upon the microalgae Heterosigma akashiwo (Rhaphidophyta). Experiments were conducted in single-factor incubation and various two-factor combination experiments in which temperature (10, 15, 25 and 30°C), salinity (10, 20, 30 and 40 g kg−1 water), irradiance (20, 100, 200 and 400 μmol m−2 s−1), and pH (5.5, 7, 8.5 and 10) were varied systematically. The growth rates of U. pertusa and H. akashiwo and the rate of microalgal growth inhibition were altered significantly by changing some of the non-nutrient factors in both the single-factor and the two-factor experiments. The optimal growth conditions for U. pertusa were 20–25°C, salinity of 30 g kg−1, irradiance level of 200–400 μmol m−2 s−1, and pH 8.5–10; optimal conditions for H. akashiwo growth were 25°C, 30 g kg−1, 100 μmol m−2 s−1 and pH 8.5, respectively. The growth inhibitory influence of U. pertusa on H. akashiwo was strongest at 25°C with low salinity (10 g kg−1), high irradiance (400 μmol m−2 s−1) and high alkalinity (pH = 10). The results of this study may be helpful in the development of methods for using green macroalgae to control the proliferation of microalgae in harmful algal blooms (HABs). In particular, these findings provide guidance regarding optimum levels of non-nutrient environmental factors in confined areas, such as aquaculture factories.

scholarly journals Algicidal Activity of Novel Indigenous Bacterial Strain, Paracoccus Sp., Against Harmful Algal Bloom Species, Karenia Mikimotoi

2021 ◽  
Author(s):  
Ning Ding ◽  
Wenjun Du ◽  
Yanlou Feng ◽  
Yuhao Song ◽  
Chao Wang ◽  
...  
Keyword(s):  
Bacterial Strain ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Harmful Algal Bloom ◽  
Growth Conditions ◽  
Inhibitory Effect ◽  
Algicidal Bacteria ◽  
Rrna Gene ◽  
Negative Effects ◽  
Karenia Mikimotoi

Abstract Harmful algal blooms have deleterious effects on aquatic ecosystems and human health. The application of algicidal bacteria is a promising and environmentally friendly method of preventing and eradicating harmful algal blooms. In this study, a screen for algicidal agents against harmful algal blooms was used to identify an algicidal bacterial strain isolated from a Karenia mikimotoi culture. Strain O-1 exhibited a strong inhibitory effect on harmful K. mikimotoi and was identified as a Paracoccus species via 16S rRNA gene sequence analysis. This strain killed K. mikimotoi by secreting active algicidal compounds, which were stable at temperatures of -80–121 °C, but these substances were sensitive to strongly acidic conditions. The algicidal properties of strain O-1 against K. mikimotoi were cell density- and time-dependent. No significant changes or negative effects were noted for two other Chlorophyta species, which highlighted the specificity of the studied algicidal substance. Finally, single-factor experiments revealed the optimum growth conditions of strain O-1 under different pH and temperature conditions. Strain O-1 therefore has potential as a bio-agent for reducing the biomass of harmful K. mikimotoi blooms.

scholarly journals Temporal dynamics of the phytoplankton community associated with environmental factors and harmful algal blooms in Acapulco Bay, Mexico

2021 ◽  
Vol 49 (1) ◽  
pp. 110-124
Author(s):  
Victor A. Cervantes-Urieta ◽  
Ma. Nieves Trujillo-Tapia ◽  
Juan Violante-González ◽  
Giovanni Moreno-Díaz ◽  
Agustín A. Rojas-Herrera ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Chlorophyll A ◽  
Rainy Season ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Temporal Dynamics ◽  
Harmful Algal Bloom ◽  
San Lorenzo ◽  
Diatom Genus ◽  
Physical And Chemical

The phytoplankton community's temporal variability associated with environmental factors and harmful algal blooms in Acapulco Bay was analyzed. Phytoplankton samples were taken monthly at three sites (MSL: Morro de San Lorenzo, CDO: Casa Díaz Ordaz, and PP: Playa Palmitas) over 11 months in 2018. The physical and chemical variables of surface water were measured in situ, and the composition and community structure of phytoplankton were analyzed. The physical and chemical characteristics studied varied significantly. The highest temperatures were obtained in September and October (September: 29.6 ± 3.58°C, October: 34.61 ± 1.83°C), whereas the highest salinities and chlorophyll-a concentrations occurred from February to May (salinity: 34.06 ± 0.38, chlorophyll-a: 2.73 ± 0.15 μg L-1). The highest oxygen concentrations were recorded during the rainy season (June 91.8% and December 100%). A total of 201 phytoplankton species were identified: 94 diatoms, 101 dinoflagellates, 4 cyanobacteria, and 2 silicoflagellates. Diatoms dominated during the rainy season, whereas dinoflagellates dominated during the dry season (June to December). A total of 17 harmful species were identified; four toxin-producing species included a diatom genus (Pseudonitszchia sp.) and three dinoflagellate species (Gymnodinium catenatum, Dinophysis caudata, and Phalacroma rotundata). One species that produces oxygen reactive species and hemolysis (Margalefidinium polykrikoides) caused a harmful algal bloom at the CDO and PP stations. The temperature is one of the most critical factors for its bloom in October.

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