Distribution of Alexandrium fundyense and A. pacificum (Dinophyceae) in the Yellow Sea and Bohai Sea

Gao, Yan; Yu, Rencheng; Chen, Jianhua; Zhang, Qing‐Chun; Kong, Fan‐Zhou; Zhou, Meng

doi:10.1016/j.marpolbul.2015.05.025

Cited by 35 publications

(20 citation statements)

References 49 publications

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“…Quantitative PCR was performed using the A. pacificum specific real-time PCR assay designed by Gao et al [7] on a QuantStudio 1 real-time PCR detection system (Applied Biosystems, Foster City, CA, USA). The primers (AtIV-F and AtIV-R) and probe (AtIV-P) targeting the LSU rRNA gene [7] were synthesized and purified using HPLC (high performance liquid chromatography) (Sangon Biotechnology, Shanghai, China).…”

Section: Quantitative Pcr (Qpcr)mentioning

confidence: 99%

Dynamics of the Toxic Dinoflagellate Alexandrium pacificum in the Taiwan Strait and Its Linkages to Surrounding Populations

Liu

Zheng

Krock

et al. 2021

Water

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The dinoflagellate Alexandrium pacificum can produce paralytic shellfish toxins and is mainly distributed in the Pacific. Blooms of A. pacificum have been frequently reported in offshore areas of the East China Sea, but not along the coast. To investigate the bloom dynamics of A. pacificum and their potential origins in the Taiwan Strait, we performed intensive sampling of both water and sediments from 2017 to 2020. Ellipsoidal cysts were identified as A. pacificum and enumerated based on microscopic observation. Their abundances were quite low but there was a maximum of 9.6 cysts cm−3 in the sediment near the Minjiang River estuary in May 2020, consistent with the high cell abundance in the water column in this area. Cells of A. pacificum were examined using a quantitative polymerase chain reaction, and they appeared to be persistent in the water column across the seasons. High densities of A. pacificum (103 cells L−1) were observed near the Jiulongjiang and Minjiang River estuary in early May 2020, where high nutrients (dissolved inorganic nitrogen and phosphate), and relatively low temperatures (20–21 °C) were also recorded. Strains isolated from the East and South China Sea exhibited the highest division rate (0.63 and 0.93 divisions d−1) at 20 and 23 °C, respectively, but the strain from the Yellow Sea showed the highest division (0.40 divisions d−1) at 17–23 °C. Strains from the East and South China Sea shared similar toxin profiles dominated by the N-sulfocarbamoyl toxins C1/2, but the strain from the Yellow Sea predominantly produced the carbamoyl toxins GTX1/4 and no C1/2. Our results suggest that both cyst germination and persistent cells in the water column might contribute to the bloom formation in the Taiwan Strait. Our results also indicate that the East and South China Sea populations are connected genetically through similar toxin formation but separated from the Yellow Sea population geographically.

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Section: Quantitative Pcr (Qpcr)mentioning

confidence: 99%

Dynamics of the Toxic Dinoflagellate Alexandrium pacificum in the Taiwan Strait and Its Linkages to Surrounding Populations

Liu

Zheng

Krock

et al. 2021

Water

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“…The quantification of A. fundyense and A. pacificum organisms in the YS was previously conducted with two TaqMan-based qPCR assays (27), according to the protocols of Hosoi-Tanabe and Sako (26) and Gao et al (28), with some modifications. The primer pairs used for A. fundyense were AtI-F (5=-GCTTGGTGGGAGTGTTGCAC-3=) and AtI-R (5=-TAAGTCCAAGGAAGGAAGCATC-3=), and the TaqMan probe was AtI-P (5=-FAM-AGAGCTTTGGGCTGTGGGTGTA-TAMRA-3=) (FAM, 6-carboxyfluorescein; TAMRA, 6-carboxytetramethylrhodamine).…”

Section: Methodsmentioning

confidence: 99%

“…The field samples were quantified with the calibration curves prepared with two strains representing A. fundyense (ATLY) and A. pacificum (ACDH) (27).…”

Section: Methodsmentioning

confidence: 99%

High Specificity of a Quantitative PCR Assay Targeting a Saxitoxin Gene for Monitoring Toxic Algae Associated with Paralytic Shellfish Toxins in the Yellow Sea

Gao

Murray

et al. 2015

Appl Environ Microbiol

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The identification of core genes involved in the biosynthesis of saxitoxin (STX) offers a great opportunity to detect toxic algae associated with paralytic shellfish toxins (PST). In the Yellow Sea (YS) in China, both toxic and nontoxic Alexandrium species are present, which makes it a difficult issue to specifically monitor PST-producing toxic algae. In this study, a quantitative PCR (qPCR) assay targeting sxtA4, a domain in the sxt gene cluster that encodes a unique enzyme involved in STX biosynthesis, was applied to analyze samples collected from the YS in spring of 2012. The abundance of two toxic species within the Alexandrium tamarense species complex, i.e., A. fundyense and A. pacificum, was also determined with TaqMan-based qPCR assays, and PSTs in net-concentrated phytoplankton samples were analyzed with high-performance liquid chromatography coupled with a fluorescence detector. It was found that the distribution of the sxtA4 gene in the YS was consistent with the toxic algae and PSTs, and the quantitation results of sxtA4 correlated well with the abundance of the two toxic species (r ‫؍‬ 0.857). These results suggested that the two toxic species were major PST producers during the sampling season and that sxtA-based qPCR is a promising method to detect toxic algae associated with PSTs in the YS. The correlation between PST levels and sxtA-based qPCR results, however, was less significant (r ‫؍‬ 0.552), implying that sxtA-based qPCR is not accurate enough to reflect the toxicity of PSTproducing toxic algae. The combination of an sxtA-based qPCR assay and chemical means might be a promising method for monitoring toxic algal blooms. S axitoxin (STX) and its analogues, commonly known as paralytic shellfish toxins (PSTs), are potent neurotoxic alkaloids (1) synthesized by marine dinoflagellates in the genera Alexandrium, Gymnodinium, and Pyrodinium (2-4) and some cyanobacteria in freshwater (5-7). PSTs ingested by humans via shellfish vectors can reversibly bind to voltage-gated Na ϩ channels and inhibit the flow of sodium ions (1, 8), which leads to paralytic poisoning symptoms, including neurological numbness, tingling and burning of the lips and skin, ataxia, and fever. Severe poisoning may lead to a loss of muscular coordination and respiratory distress, which can be fatal (9).The biosynthetic pathway for STX, a compound with a complex chemical structure, remained a mystery for a long time prior to the identification of the STX synthesis genes in several cyanobacterial species (10). The identification and characterization of this set of core genes involved in STX synthesis provided the possibility of distinguishing the toxic potential of incipient blooms. A variety of genes related to toxin synthesis in cyanobacteria have been applied successfully not only in the detection, differentiation, and quantification of toxic cyanobacteria but also in studies on the regulation of toxin biosynthesis (7,(11)(12)(13)(14). In contrast, the genetic basis for STX production in dinoflagellates remains elusive, due to...

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“…Characterization of sxt genes has made the development of PST-producing strain specific qPCR assays [214,215,224,225], and studies have shown that the genomic copy numbers of sxt genes vary less compared to rRNA genes, allowing for more accurate cell density estimates [197,223,224]. These assays have been successfully trialed to indicate the presence of toxic strains in seawater [215,224,225,226], and in commercially harvested oysters [227]. The detection of the toxic strains at low concentrations in seawater, enabled by sxt gene-based qPCR assays, provides a means for early warning systems designed to detect developing harmful blooms.…”

Section: Dinoflagellate Toxinsmentioning

confidence: 99%

The Genetic Basis of Toxin Biosynthesis in Dinoflagellates

et al. 2019

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In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth rates. One factor that may play a role in their ecological success is the production of complex secondary metabolite compounds that can have anti-predator, allelopathic, or other toxic effects on marine organisms, and also cause seafood poisoning in humans. Our knowledge about the genes involved in toxin biosynthesis in dinoflagellates is currently limited due to the complex genomic features of these organisms. Most recently, the sequencing of dinoflagellate transcriptomes has provided us with valuable insights into the biosynthesis of polyketide and alkaloid-based toxin molecules in dinoflagellate species. This review synthesizes the recent progress that has been made in understanding the evolution, biosynthetic pathways, and gene regulation in dinoflagellates with the aid of transcriptomic and other molecular genetic tools, and provides a pathway for future studies of dinoflagellates in this exciting omics era.

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Distribution of Alexandrium fundyense and A. pacificum (Dinophyceae) in the Yellow Sea and Bohai Sea

Cited by 35 publications

References 49 publications

Dynamics of the Toxic Dinoflagellate Alexandrium pacificum in the Taiwan Strait and Its Linkages to Surrounding Populations

Dynamics of the Toxic Dinoflagellate Alexandrium pacificum in the Taiwan Strait and Its Linkages to Surrounding Populations

High Specificity of a Quantitative PCR Assay Targeting a Saxitoxin Gene for Monitoring Toxic Algae Associated with Paralytic Shellfish Toxins in the Yellow Sea

The Genetic Basis of Toxin Biosynthesis in Dinoflagellates

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