scholarly journals Transcriptional Responses of Flavin-Containing Monooxygenase Genes in Scallops Exposed to PST-Producing Dinoflagellates Implying Their Involvements in Detoxification

2021 ◽  
Vol 8 ◽  
Author(s):  
Lingling Kong ◽  
Pingping Liu ◽  
Moli Li ◽  
Huizhen Wang ◽  
Jiaoxia Shi ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Chlamys Farreri ◽  
Transcriptional Responses ◽  
Patinopecten Yessoensis ◽  
Alexandrium Catenella ◽  
Paralytic Shellfish Toxins ◽  
Paralytic Shellfish ◽  
Genome Screening ◽  
Trochophore Stage

Flavin-containing monooxygenase (FMO) is one of the most prominent xenobiotic metabolic enzymes. It can catalyze the conversion of heteroatom-containing chemicals to polar, readily excretable metabolites and is considered an efficient detoxification system for xenobiotics. Bivalves can accumulate paralytic shellfish toxins (PSTs) produced by dinoflagellates, especially during outbreaks of harmful algal blooms. Exploring FMO genes in bivalves may contribute to a better understanding of the adaptation of these species and the mechanisms of PSTs bioavailability. Therefore, through genome screening, we examined the expansion of FMO genes in two scallops (Patinopecten yessoensis and Chlamys farreri) and found a new subfamily (FMO_like). Our expression analyses revealed that, in both scallops, members of the FMO_N-oxide and FMO_like subfamilies were mainly expressed from the D-stage larvae to juveniles, whereas the FMO_GS-OX subfamily genes were mainly expressed at and prior to the trochophore stage. In adult organs, higher expressions of FMOs were observed in the kidney and hepatopancreas than in other organs. After exposure to PST-producing algae, expression changes in FMOs occurred in hepatopancreas and kidney of both scallops, with more members being up-regulated in hepatopancreas than in kidney for Alexandrium catenella exposure, while more up-regulated FMOs were found in kidney than in hepatopancreas of C. farreri exposed to A. minutum. Our findings suggest the adaptive functional diversity of scallop FMO genes in coping with the toxicity of PST-producing algae.

scholarly journals Electrophysiological Evaluation of Pacific Oyster (Crassostrea gigas) Sensitivity to Saxitoxin and Tetrodotoxin

Marine Drugs ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. 380
Author(s):  
Floriane Boullot ◽  
Caroline Fabioux ◽  
Hélène Hégaret ◽  
Pierre Boudry ◽  
Philippe Soudant ◽  
...  
Keyword(s):  
Crassostrea Gigas ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Alexandrium Minutum ◽  
Paralytic Shellfish Toxins ◽  
Pacific Oysters ◽  
Paralytic Shellfish ◽  
Good Potential ◽  
First Time ◽  
Micromolar Range

Pacific oysters (Crassostrea gigas) may bio-accumulate high levels of paralytic shellfish toxins (PST) during harmful algal blooms of the genus Alexandrium. These blooms regularly occur in coastal waters, affecting oyster health and marketability. The aim of our study was to analyse the PST-sensitivity of nerves of Pacific oysters in relation with toxin bio-accumulation. The results show that C. gigas nerves have micromolar range of saxitoxin (STX) sensitivity, thus providing intermediate STX sensitivity compared to other bivalve species. However, theses nerves were much less sensitive to tetrodotoxin. The STX-sensitivity of compound nerve action potential (CNAP) recorded from oysters experimentally fed with Alexandrium minutum (toxic-alga-exposed oysters), or Tisochrysis lutea, a non-toxic microalga (control oysters), revealed that oysters could be separated into STX-resistant and STX-sensitive categories, regardless of the diet. Moreover, the percentage of toxin-sensitive nerves was lower, and the STX concentration necessary to inhibit 50% of CNAP higher, in recently toxic-alga-exposed oysters than in control bivalves. However, no obvious correlation was observed between nerve sensitivity to STX and the STX content in oyster digestive glands. None of the nerves isolated from wild and farmed oysters was detected to be sensitive to tetrodotoxin. In conclusion, this study highlights the good potential of cerebrovisceral nerves of Pacific oysters for electrophysiological and pharmacological studies. In addition, this study shows, for the first time, that C. gigas nerves have micromolar range of STX sensitivity. The STX sensitivity decreases, at least temporary, upon recent oyster exposure to dinoflagellates producing PST under natural, but not experimental environment.

scholarly journals Paralytic Shellfish Toxins (PST)-Transforming Enzymes: A Review

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 344
Author(s):  
Mariana I. C. Raposo ◽  
Maria Teresa S. R. Gomes ◽  
Maria João Botelho ◽  
Alisa Rudnitskaya
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Paralytic Shellfish Poisoning ◽  
Shellfish Poisoning ◽  
Practical Applications ◽  
Drug Candidates ◽  
Shellfish Toxins ◽  
Paralytic Shellfish Toxins ◽  
Voltage Gated Sodium Channels ◽  
Paralytic Shellfish

Paralytic shellfish toxins (PSTs) are a group of toxins that cause paralytic shellfish poisoning through blockage of voltage-gated sodium channels. PSTs are produced by prokaryotic freshwater cyanobacteria and eukaryotic marine dinoflagellates. Proliferation of toxic algae species can lead to harmful algal blooms, during which seafood accumulate high levels of PSTs, posing a health threat to consumers. The existence of PST-transforming enzymes was first remarked due to the divergence of PST profiles and concentrations between contaminated bivalves and toxigenic organisms. Later, several enzymes involved in PST transformation, synthesis and elimination have been identified. The knowledge of PST-transforming enzymes is necessary for understanding the processes of toxin accumulation and depuration in mollusk bivalves. Furthermore, PST-transforming enzymes facilitate the obtainment of pure analogues of toxins as in natural sources they are present in a mixture. Pure compounds are of interest for the development of drug candidates and as analytical reference materials. PST-transforming enzymes can also be employed for the development of analytical tools for toxin detection. This review summarizes the PST-transforming enzymes identified so far in living organisms from bacteria to humans, with special emphasis on bivalves, cyanobacteria and dinoflagellates, and discusses enzymes’ biological functions and potential practical applications.

scholarly journals The effect of iron on Chilean Alexandrium catenella growth and paralytic shellfish toxin production as related to algal blooms

BioMetals ◽  
2021 ◽  
Author(s):  
Kyoko Yarimizu ◽  
Jorge I. Mardones ◽  
Javier Paredes-Mella ◽  
Luis Norambuena-Subiabre ◽  
Carl J. Carrano ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Culture Media ◽  
Iron Concentration ◽  
Toxin Production ◽  
Southern Chile ◽  
Alexandrium Catenella ◽  
Paralytic Shellfish Toxin ◽  
Paralytic Shellfish ◽  
Shellfish Toxin

AbstractThe dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms (HABs) worldwide. Blooms of this species have repeatedly brought severe ecological and economic impacts to Chile, especially in the southern region, where the shellfish and salmon industries are world-famous. The mechanisms of such HABs have been intensively studied but are still unclear. Nutrient overloading is one of the often-discussed drivers for HABs. The present study used the A. catenella strain isolated from southern Chile to investigate how iron conditions could affect their growth and toxin production as related to HAB. Our results showed that an optimum concentration of iron was pivotal for proper A. catenella growth. Thus, while excess iron exerted a toxic effect, low iron media led to iron insufficiency and growth inhibition. In addition, the study shows that the degree of paralytic shellfish toxin production by A. catenella varied depending on the iron concentration in the culture media. The A. catenella strain from southern Chile produced GTX1-4 exclusively in the fmol cell−1 scale. Based on these findings, we suggest that including iron and paralytic shellfish toxin measurements in the fields can improve the current HAB monitoring and contribute to an understanding of A. catenella bloom dynamics in Chile.

scholarly journals Predator lipids induce paralytic shellfish toxins in bloom-forming algae

2015 ◽  
Vol 112 (20) ◽  
pp. 6395-6400 ◽  
Author(s):  
Erik Selander ◽  
Julia Kubanek ◽  
Mats Hamberg ◽  
Mats X. Andersson ◽  
Gunnar Cervin ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Large Scale ◽  
Fold Increase ◽  
Grazing Pressure ◽  
Alexandrium Minutum ◽  
Shellfish Toxins ◽  
Paralytic Shellfish Toxins ◽  
Paralytic Shellfish ◽  
Species Specific

Interactions among microscopic planktonic organisms underpin the functioning of open ocean ecosystems. With few exceptions, these organisms lack advanced eyes and thus rely largely on chemical sensing to perceive their surroundings. However, few of the signaling molecules involved in interactions among marine plankton have been identified. We report a group of eight small molecules released by copepods, the most abundant zooplankton in the sea, which play a central role in food webs and biogeochemical cycles. The compounds, named copepodamides, are polar lipids connecting taurine via an amide to isoprenoid fatty acid conjugate of varying composition. The bloom-forming dinoflagellate Alexandrium minutum responds to pico- to nanomolar concentrations of copepodamides with up to a 20-fold increase in production of paralytic shellfish toxins. Different copepod species exude distinct copepodamide blends that contribute to the species-specific defensive responses observed in phytoplankton. The signaling system described here has far reaching implications for marine ecosystems by redirecting grazing pressure and facilitating the formation of large scale harmful algal blooms.

scholarly journals New markers for qPCR detection of the dinoflagellate Alexandrium catenella in Chile

2021 ◽  
Author(s):  
Javiera Espinoza ◽  
Kyoko Yarimizu ◽  
Satoshi Nagai ◽  
Oscar Espinoza Gonzalez ◽  
Leonardo Guzman ◽  
...  
Keyword(s):  
Early Detection ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Primary Source ◽  
Paralytic Shellfish Poisoning ◽  
Distribution Range ◽  
Shellfish Poisoning ◽  
Alexandrium Catenella ◽  
Monitoring Programs ◽  
Paralytic Shellfish

Alexandrium catenella (Whedon & Kofoid) is a dinoflagellate known as a primary source of paralytic shellfish poisoning in Chile. The distribution range of harmful algal blooms generated by this species has extended during the last decades, and the frequency of these events has increased. In this work, we developed TaqMan markers from Chilean strains that can be used to identify and quantify through qPCR, which can be implemented in monitoring programs for the early detection of this species.

scholarly journals Change in Paralytic Shellfish Toxins in the Mussel Mytilus galloprovincialis Depending on Dynamics of Harmful Alexandrium catenella (Group I) in the Geoje Coast (South Korea) during Bloom Season

Toxins ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 442
Author(s):  
Seung Ho Baek ◽  
Jung Min Choi ◽  
Minji Lee ◽  
Bum Soo Park ◽  
Yuchengmin Zhang ◽  
...  
Keyword(s):  
Human Consumption ◽  
Nakdong River ◽  
Alexandrium Catenella ◽  
Low Salinity ◽  
Shellfish Toxins ◽  
Paralytic Shellfish Toxins ◽  
Group I ◽  
Paralytic Shellfish ◽  
High Nutrient ◽  
The Nakdong River

Paralytic shellfish toxins (PSTs) produced by Alexandrium catenella (formerly A. tamarense) in Korean coastal waters caused the deaths of four people (in 1986 and 1996) who consumed contaminated mussels (Mytilus edulis). This led to more detailed consideration of the risks of PST outbreaks and incidents in Korea, including the introduction of shellfish collection bans. In this study, we investigated the relationships between A. catenella population dynamics and PST accumulation in the mussel M. galloprovincialis. Discharges from the Nakdong River affect the environmental conditions along the Geoje coast, resulting in low salinity and high nutrient levels that trigger blooms of A. catenella. At the toxin peak on 24 April 2017, the toxins detected in A. catenella cells were C1, gonyautoxin (GTX)1 and GTX2, whereas the concentrations of PSTs in M. galloprovincialis were high and in the order of GTX4 > GTX1 > GTX3 > saxitoxin (STX) > GTX2 > neoSTX > decarbamoylgonyautoxin (dcGTX)2 > dc GTX3. The PST level in mussels was also high. At 15 °C, the PSTs are constantly found to be higher (10-fold higher in 2017 and 30-fold higher in 2018) than safe levels for human consumption (80 μg STX diHCl equivalents 100 g−1).

scholarly journals Saxitoxin and tetrodotoxin bioavailability increases in future oceans

2019 ◽  
Author(s):  
C.C. Roggatz ◽  
N. Fletcher ◽  
D.M. Benoit ◽  
A.C. Algar ◽  
A. Doroff ◽  
...  
Keyword(s):  
Species Interactions ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Paralytic Shellfish Poisoning ◽  
Ecosystem Stability ◽  
Shellfish Poisoning ◽  
Marine Life ◽  
Paralytic Shellfish ◽  
Water Ph ◽  
Ph Increase

Increasing atmospheric levels of carbon dioxide are largely absorbed by the world’s oceans, decreasing surface water pH1. In combination with increasing ocean temperatures, these changes have been identified as a major sustainability threat to future marine life2. Interactions between marine organisms are known to depend on biomolecules, but the influence of oceanic pH on their bioavailability and functionality remains unexplored. Here we show that global change significantly impacts two ecological keystone molecules3 in the ocean, the paralytic toxins saxitoxin (STX) and tetrodotoxin (TTX). Increasing temperatures and declining pH increase the abundance of the toxic forms of these two neurotoxins in the water. Our geospatial global model highlights where this increased toxicity could intensify the devastating impact of harmful algal blooms on ecosystems in the future, for example through an increased incidence of paralytic shellfish poisoning (PSP). We also use these results to calculate future saxitoxin toxicity levels in Alaskan clams, Saxidomus gigantea, showing critical exceedance of limits save for consumption. Our findings for TTX and STX exemplarily highlight potential consequences of changing pH and temperature on chemicals dissolved in the sea. This reveals major implications not only for ecotoxicology, but also for chemical signals mediating species interactions such as foraging, reproduction, or predation in the ocean with unexplored consequences for ecosystem stability and ecosystem services.

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.

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