scholarly journals sxtA-Based Quantitative Molecular Assay To Identify Saxitoxin-Producing Harmful Algal Blooms in Marine Waters

2011 ◽  
Vol 77 (19) ◽  
pp. 7050-7057 ◽  
Author(s):  
Shauna A. Murray ◽  
Maria Wiese ◽  
Anke Stüken ◽  
Steve Brett ◽  
Ralf Kellmann ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Harmful Algal Bloom ◽  
Effective Means ◽  
Molecular Genetic ◽  
Alexandrium Tamarense ◽  
Alexandrium Catenella ◽  
Content Type ◽  
Eukaryotic Phytoplankton ◽  
Novel Method

ABSTRACTThe recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal bloomsin situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the genesxtAthat encodes a unique enzyme putatively involved in thesxtpathway in marine dinoflagellates,sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producingAlexandriumandGymnodinium catenatumand was not detected in the non-STX-producingAlexandriumspecies, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However,sxtA4was also detected in the non-STX-producing strain ofAlexandrium tamarense, Tasmanian ribotype. We investigated the copy number ofsxtA4in three strains ofAlexandrium catenellaand found it to be relatively constant among strains. Using our novel method, we detected and quantifiedsxtA4in three environmental blooms ofAlexandrium catenellathat led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring.

scholarly journals Deep Learning for Simulating Harmful Algal Blooms Using Ocean Numerical Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Sang-Soo Baek ◽  
JongCheol Pyo ◽  
Yong Sung Kwon ◽  
Seong-Jun Chun ◽  
Seung Ho Baek ◽  
...  
Keyword(s):  
Deep Learning ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Effective Means ◽  
Ocean Model ◽  
Alexandrium Catenella ◽  
The Public ◽  
Global Issue ◽  
Simulated Distribution ◽  
Classification And Regression

In several countries, the public health and fishery industries have suffered from harmful algal blooms (HABs) that have escalated to become a global issue. Though computational modeling offers an effective means to understand and mitigate the adverse effects of HABs, it is challenging to design models that adequately reflect the complexity of HAB dynamics. This paper presents a method involving the application of deep learning to an ocean model for simulating blooms of Alexandrium catenella. The classification and regression convolutional neural network (CNN) models are used for simulating the blooms. The classification CNN determines the bloom initiation while the regression CNN estimates the bloom density. GoogleNet and Resnet 101 are identified as the best structures for the classification and regression CNNs, respectively. The corresponding accuracy and root means square error values are determined as 96.8% and 1.20 [log(cells L–1)], respectively. The results obtained in this study reveal the simulated distribution to follow the Alexandrium catenella bloom. Moreover, Grad-CAM identifies that the salinity and temperature contributed to the initiation of the bloom whereas NH4-N influenced the growth of the bloom.

scholarly journals Bacilysin from Bacillus amyloliquefaciens FZB42 Has Specific Bactericidal Activity against Harmful Algal Bloom Species

2014 ◽  
Vol 80 (24) ◽  
pp. 7512-7520 ◽  
Author(s):  
Liming Wu ◽  
Huijun Wu ◽  
Lina Chen ◽  
Shanshan Xie ◽  
Haoyu Zang ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Bacillus Amyloliquefaciens ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Harmful Algal Bloom ◽  
Algal Cell ◽  
Algal Species ◽  
Inhibitory Effect ◽  
Cell Organelle ◽  
Content Type

ABSTRACTHarmful algal blooms, caused by massive and exceptional overgrowth of microalgae and cyanobacteria, are a serious environmental problem worldwide.In the present study, we looked forBacillusstrains with sufficiently strong anticyanobacterial activity to be used as biocontrol agents. Among 24 strains,Bacillus amyloliquefaciensFZB42 showed the strongest bactericidal activity againstMicrocystis aeruginosa, with a kill rate of 98.78%. The synthesis of the anticyanobacterial substance did not depend on Sfp, an enzyme that catalyzes a necessary processing step in the nonribosomal synthesis of lipopeptides and polyketides, but was associated with thearogene cluster that is involved in the synthesis of thesfp-independent antibiotic bacilysin. Disruption ofbacB, the gene in the cluster responsible for synthesizing bacilysin, or supplementation with the antagonistN-acetylglucosamine abolished the inhibitory effect, but this was restored when bacilysin synthesis was complemented. Bacilysin caused apparent changes in the algal cell wall and cell organelle membranes, and this resulted in cell lysis. Meanwhile, there was downregulated expression ofglmS,psbA1,mcyB, andftsZ—genes involved in peptidoglycan synthesis, photosynthesis, microcystin synthesis, and cell division, respectively. In addition, bacilysin suppressed the growth of other harmful algal species. In summary, bacilysin produced byB. amyloliquefaciensFZB42 has anticyanobacterial activity and thus could be developed as a biocontrol agent to mitigate the effects of harmful algal blooms.

Using Fundamental Optical Property Sensors for Characterization of Biogeochemical Materials and Processes in Marine Waters

2008 ◽  
Vol 42 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Casey Moore
Keyword(s):  
Optical Properties ◽  
Optical Property ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Natural Waters ◽  
Harmful Algal Bloom ◽  
Light Level ◽  
Ecosystem Dynamics ◽  
Wide Range ◽  
Biogeochemical Parameters

Over the past ten years, efforts to characterize the optical properties of Earth's natural waters have largely merged with the need to better understand underlying biological and chemical processes. Fundamental optical properties such as light level, absorption, scattering and fluorescence are now being utilized with increasing effectiveness to specify particulate and dissolved in-water components in a wide range of applications, including detection of harmful algal blooms, studying ecosystem dynamics, monitoring the effect of industrial and agricultural pollutants, and understanding carbon sequestration processes in the oceans. A diverse offering of commercial optical sensing products capable for research, routine measurements, and in some cases, operational monitoring are now available. These technologies have provided the scientific community with a set of tools for developing, testing, and placing into practice analytical and semi-analytical methods to infer specific biogeochemical parameters and processes. As a result, new, more specialized sensors are now emerging. New sensors couple basic optical property measurements with processing algorithms to provide specific indicators for Harmful Algal Bloom (HAB) identification, carbon products, nutrients, and particle size distributions. The basic measurement methods are described and examples of devices incorporating them are provided to illustrate their use in modern oceanographic research and monitoring.

scholarly journals The Southeast Alaska Tribal Ocean Research (SEATOR) Partnership: Addressing Data Gaps in Harmful Algal Bloom Monitoring and Shellfish Safety in Southeast Alaska

Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 407 ◽  
Author(s):  
John R. Harley ◽  
Kari Lanphier ◽  
Esther G. Kennedy ◽  
Tod A. Leighfield ◽  
Allison Bidlack ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Harmful Algal Bloom ◽  
Sea Surface ◽  
Southeast Alaska ◽  
Paralytic Shellfish Toxins ◽  
Tribal Governments ◽  
Salinity Data

Many communities in Southeast Alaska harvest shellfish such as mussels and clams as an important part of a subsistence or traditional diet. Harmful algal blooms (HABs) of phytoplankton such as Alexandrium spp. produce toxins that can accumulate in shellfish tissues to concentrations that can pose a hazard for human health. Since 2013, several tribal governments and communities have pooled resources to form the Southeast Alaska Tribal Ocean Research (SEATOR) network, with the goal of minimizing risks to seafood harvest and enhancing food security. SEATOR monitors toxin concentrations in shellfish and collects and consolidates data on environmental variables that may be important predictors of toxin levels such as sea surface temperature and salinity. Data from SEATOR are publicly available and are encouraged to be used for the development and testing of predictive algorithms that could improve seafood risk assessment in Southeast Alaska. To date, more than 1700 shellfish samples have been analyzed for paralytic shellfish toxins (PSTs) in more than 20 locations, with potentially lethal concentrations observed in blue mussels (Mytilus trossulus) and butter clams (Saxidomus gigantea). Concentrations of PSTs exhibit seasonality in some species, and observations of Alexandrium are correlated to sea surface temperature and salinity; however, concentrations above the threshold of concern have been found in all months, and substantial variation in concentrations of PSTs remain unexplained.

scholarly journals Mapping the Distribution of Cysts from the Toxic Dinoflagellate Cochlodinium polykrikoides in Bloom-Prone Estuaries by a Novel FluorescenceIn SituHybridization Assay

2015 ◽  
Vol 82 (4) ◽  
pp. 1114-1125 ◽  
Author(s):  
Theresa K. Hattenrath-Lehmann ◽  
Yu Zhen ◽  
Ryan B. Wallace ◽  
Ying-Zhong Tang ◽  
Christopher J. Gobler
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Large Subunit ◽  
Cross Reactivity ◽  
Epifluorescence Microscopy ◽  
Lsu Rdna ◽  
Cochlodinium Polykrikoides ◽  
Content Type ◽  
Ecosystem Studies ◽  
Resting Cysts

ABSTRACTCochlodinium polykrikoidesis a cosmopolitan dinoflagellate that is notorious for causing fish-killing harmful algal blooms (HABs) across North America and Asia. While recent laboratory and ecosystem studies have definitively demonstrated thatCochlodiniumforms resting cysts that may play a key role in the dynamics of its HABs, uncertainties regarding cyst morphology and detection have prohibited even a rudimentary understanding of the distribution ofC. polykrikoidescysts in coastal ecosystems. Here, we report on the development of a fluorescencein situhybridization (FISH) assay using oligonucleotide probes specific for the large subunit (LSU) ribosomal DNA (rDNA) ofC. polykrikoides. The LSU rDNA-targeted FISH assay was used with epifluorescence microscopy and was iteratively refined to maximize the fluorescent reaction withC. polykrikoidesand minimize cross-reactivity. The final LSU rDNA-targeted FISH assay was found to quantitatively recover cysts made by North American isolates ofC. polykrikoidesbut not cysts formed by other common cyst-forming dinoflagellates. The method was then applied to identify and mapC. polykrikoidescysts across bloom-prone estuaries. Annual cyst and vegetative cell surveys revealed that elevated densities ofC. polykrikoidescysts (>100 cm−3) during the spring of a given year were spatially consistent with regions of dense blooms the prior summer. The identity of cysts in sediments was confirmed via independent amplification ofC. polykrikoidesrDNA. This study mappedC. polykrikoidescysts in a natural marine setting and indicates that the excystment of cysts formed by this harmful alga may play a key role in the development of HABs of this species.

scholarly journals Genomic Insights into Processes Driving the Infection of Alexandrium tamarense by the Parasitoid Amoebophrya sp.

2014 ◽  
Vol 13 (11) ◽  
pp. 1439-1449 ◽  
Author(s):  
Yameng Lu ◽  
Sylke Wohlrab ◽  
Gernot Glöckner ◽  
Laure Guillou ◽  
Uwe John
Keyword(s):  
Harmful Algal Bloom ◽  
Alexandrium Tamarense ◽  
Host Recognition ◽  
Maturation Stage ◽  
Infection Cycle ◽  
Data Set ◽  
Content Type ◽  
Infection Dynamics ◽  
Final Maturation ◽  
Phase Signal

ABSTRACTThe regulatory circuits during infection of dinoflagellates by their parasites are largely unknown on the molecular level. Here we provide molecular insights into these infection dynamics.Alexandrium tamarenseis one of the most prominent harmful algal bloom dinoflagellates. Its pathogen, the dinoflagellate parasitoidAmoebophryasp., has been observed to infect and control the blooms of this species. We generated a data set of transcripts from three time points (0, 6, and 96 h) during the infection of this parasite-host system. Assembly of all transcript data from the parasitoid (>900,000 reads/313 Mbp with 454/Roche next-generation sequencing [NGS]) yielded 14,455 contigs, to which we mapped the raw transcript reads of each time point of the infection cycle. We show that particular surface lectins are expressed at the beginning of the infection cycle which likely mediate the attachment to the host cell. In a later phase, signal transduction-related genes together with transmembrane transport and cytoskeleton proteins point to a high integration of processes involved in host recognition, adhesion, and invasion. At the final maturation stage, cell division- and proliferation-related genes were highly expressed, reflecting the fast cell growth and nuclear division of the parasitoid. Our molecular insights into dinoflagellate parasitoid interactions point to general mechanisms also known from other eukaryotic parasites, especially from the Alveolata. These similarities indicate the presence of fundamental processes of parasitoid infection that have remained stable throughout evolution within different phyla.

Growth performance of Alexandrium catenella from the Chilean fjords under different environmental drivers: plasticity as a response to a highly variable environment

2020 ◽  
Vol 42 (2) ◽  
pp. 119-134 ◽  
Author(s):  
Javier Paredes-Mella ◽  
Daniel Varela ◽  
Pamela Fernández ◽  
Oscar Espinoza-González
Keyword(s):  
Light Intensity ◽  
Growth Performance ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Optimal Growth ◽  
N:P Ratio ◽  
Environmental Drivers ◽  
Growth Responses ◽  
Variable Environment ◽  
Alexandrium Catenella

Abstract Alexandrium catenella, the main species associated with harmful algal blooms, has progressively increased its distribution through one of the most extensive and highly variable fjord systems in the world. In order to understand this successful expansion, we evaluated the effects of different salinities, light intensity, temperatures, nitrogen (N) forms and nitrogen/phosphate (N:P) ratio levels on the growth performance, using clones isolated from different locations across its wide geographic distribution. Results showed that the growth responses were plastic and, in some cases, different reaction norms among clones were observed. Despite plasticity, the optimal growth of A. catenella (i.e. highest growth rate and highest maximal cells density) was reached within a narrow thermal range (12–15°C), while salinity (20–30 PSU) and light intensity (20–120 μmol m−2 s−1) ranges were wider. These results are partially consistent with the highest cell densities recorded in the field. Furthermore, optimal growth was reached using reduced forms of nitrogen (i.e. urea and NH4+) and in unbalanced N:P ratios (18:1 and 30:1). These characteristics likely allow A. catenella to grow in highly variable environmental conditions and might partly explain the recent expansion of this species.

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