Allan Cembella

Verified

Allan verified their affiliation via an institutional email.

Learn more

Verified

Allan verified their affiliation via an institutional email.

Learn more

• PhD
• Professor Emeritus at Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Members of the benthic marine dinoflagellate genus Amphidinium produce a variety of bioactive compounds, exhibiting potent cytotoxicity in cell assays. Crude methanolic extracts from three genetically distinct cultured strains of A. eilatiense J.J. Lee were screened for cytotoxicity against three human breast and four lung cancer cell lines to eval...

The composition of marine phytoplankton communities and environmental factors influencing their dynamics establish the trophic state of coastal ecosystems. The spatial distribution of the microphytoplankton community in Acapulco Bay, Mexico, was determined during two climatic seasons (dry and rainy). Dinoflagellates constituted the dominant group o...

Invitation to contribute to this special issue

Interactions between bacterial microbiota and epibenthic species of the dinoflagellate Prorocentrum may define the onset and persistence of benthic harmful algal blooms (bHABs). Chemical ecological interactions within the dinoflagellate phycosphere potentially involve a complex variety of organic molecules, metabolites, and toxins, including undefi...

Mass mortality events (MMEs) are defined as the death of large numbers of fish over a short period of time. These events can result in catastrophic losses to the Atlantic salmon aquaculture industry and the local economy. However, they are challenging to understand because of their relative infrequency and the high number of potential factors invol...

The genus Amphidinium Clap. & J. Lachm. comprises a high diversity of planktonic and benthic (epiphytic and sand-dwelling) dinoflagellates from marine and freshwater ecosystems. High morphological plasticity and vaguely defined genus characteristics (e.g., a small epicone size) have complicated the clear delineation of species boundaries. Although...

Globally, there are 3 400 to 4 000 described species of marine microalgae but only 1 to 2 percent are considered to be harmful. Harmful algal blooms (HABs) have significant impacts on food safety and security through contamination or mass mortalities of aquatic organisms. The impacts and mass mortalities of marine species caused by harmful algae ar...

Background: Mexican studies on marine benthic dinoflagellates (MBD) began in 1942 from the offshore region of Oaxaca, based on water column samples. Subsequently, in ten Mexican maritime states, both epibenthos and plankton samples have been collected, species have been cultured, and field and laboratory studies have been carried out. Goals: The o...

The marine dinoflagellate Alexandrium Halim represents perhaps the most significant and intensively studied genus with respect to species diversity, life history strategies, toxigenicity, biogeographical distribution, and global magnitude and consequences harmful algal blooms (HABs). The socioeconomic impacts, environmental and human health risks,...

Epibenthic dinoflagellates occur globally and include many toxin-producing species of concern to human health and benthic ecosystem function. Such benthic harmful algal blooms (BHABs) have been well described from tropical and sub-tropical coastal environments, but assessments from north temperate waters, e.g., northern Europe, and polar regions ar...

Many benthic dinoflagellates produce polyketide-derived polyether toxins responsible for diverse seafood poisoning syndromes, such as diarrhetic shellfish poisoning and ciguatera fish poisoning. In Mexico, bHAB events have received recent public health and scientific attention, but many species lack molecular identification, and phylogeographic and...

Members of the Prorocentrum lima species complex (PLSC) are most frequently found in high cell abundance in the tropics and sub-tropics and are almost invariably toxigenic. Epiphytic and planktonic bacteria are known to co-occur with such toxigenic Prorocentrum but reciprocal allelochemical interactions with the dinoflagellate microbiome have been...

A bloom of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway during May and June 2019 was the most harmful algal event ever recorded in the region, causing massive mortalities of farmed salmon. Accordingly, oceanographic and biodiversity aspects of the bloom were studied in unprecedented detail, based on metabarcoding and...

The marine dinoflagellate genus Prorocentrum Ehrenberg comprises many species occupying primarily benthic or epiphytic habitats, particularly in tropical and sub-tropical waters. Despite concerted efforts to establish phylogenetic associations, there remain unresolved issues in defining morphospecies and membership in species complexes. The study d...

Naturally occurring neurotoxins belonging to two structurally distinct groups of guanidinium alkaloids known collectively as saxitoxins (STXs) and tetrodotoxins (TTXs) share a high affinity and ion flux blockage capacity for voltage-gated sodium ion channels (Nav). Both toxin groups are produced by marine microorganisms and widely distributed among...

Benthic dinoflagellates produce a wide array of bioactive compounds, primarily polyketides, that cause toxic effects on human consumers of seafood and perhaps mediate species interactions in the benthic microenvironment. This study assesses toxic and other bioactive effects of the benthic dinoflagellate Amphidinium operculatum (strain AA60) in two...

Bacterial diversity was explored among field samples and cultured isolates from coral reefs within the Veracruz Reef System. Bacterioplankton and bacteriobenthos were characterized by pyrosequencing 16S rRNA genes. Identified sequences belonged to the kingdom Bacteria and classified into 33 phyla. Proteobacteria (likely SAR11 clade) dominated in co...

Harmful algal blooms (HAB) are recurrent phenomena in northern Europe along the coasts of the Baltic Sea, Kattegat-Skagerrak, eastern North Sea, Norwegian Sea and the Barents Sea. These HABs have caused occasional massive losses for the aquaculture industry and have chronically affected socioeconomic interests in several ways. This status review gi...

The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area fro...

The productive but highly exposed coastline of the southern Benguela eastern boundary upwelling system offers limited natural environment for aquaculture. Saldanha Bay located on the west coast of South Africa is one of the few embayments on the coastline that provides a productive and relatively sheltered environment suitable for the cultivation o...

The dinoflagellate genus Prorocentrum is globally represented by a wide variety of species found upon benthic and/or epiphytic substrates. Many epibenthic Prorocentrum species produce lipophilic polyether toxins, some of which act as potent protein phosphatase inhibitors and tumor-promoters associated with Diarrheic Shellfish Poisoning (DSP). Most...

Climate change alters environmental conditions that are expected to have a profound effect on the biodiversity, community composition, and metabolic processes of microeukaryotic plankton in Arctic and Subarctic coastal waters. The molecular biodiversity [large subunit (LSU) rRNA gene] of three plankton size-fractions (micro-, nano-, and picoplankto...

Many benthic dinoflagellates are known or suspected producers of lipophilic polyether phycotoxins, particularly in tropical and subtropical coastal zones. These toxins are responsible for diverse intoxication events of marine fauna and human consumers of seafood, but most notably in humans, they cause toxin syndromes known as diarrhetic shellfish p...

Spirolides are polyether cyclic imines considered as “fast acting toxins.” Long-term human health consequences of spirolide ingestion are uncertain, and hence regulatory limits for human consumption have not been established. Nevertheless, monitoring these toxins in shellfish is essential because they can interfere with detection by mouse bioassay...

The marine dinoflagellate Lingulodinium polyedra is a toxigenic species capable of forming high magnitude and occasionally harmful algal blooms (HABs), particularly in temperate coastal waters throughout the world. Three cultured isolates of L. polyedra from a fjord system on the Skagerrak coast of Sweden were analyzed for their growth characterist...

Fact sheets present information on distribution, toxicity and morphology for the following harmful algal species: Alexandrium, Amphidomataceae, Aureococcus anophagefferens & Aureoumbra lagunensis, Ceratium furca, Chattonella marina, Cochlodinium, Cyanobacteria, Dinophysis acuminata, Fibrocapsa japonica, Gambierdiscus and Gymnodinium catenatum. The...

This fact sheet presents information on distribution, toxicity and morphology for the following harmful algal species: Alexandrium.

This fact sheet presents information on distribution, toxicity and morphology for the following harmful algal species: Gymnodinium catenatum.

Coastal systems partially surrounded by land such as coastal embayments, estuaries and fjords have characteristics that affect the development of harmful algal blooms. These include stronger links between the water column and bottom sediments, a limited exchange with offshore waters and greater cell retention. Sub-mesoscale and high-frequency proce...

The recently established diatom genus Shionodiscus is characterized as possessing a labiate process on the valve face and strutted processes with long internal and reduced, or no, external extensions. Many Thalassiosira species with these features were transferred to this new genus, as well as some with short internal, strutted process extensions....

Neurotoxins belonging to the group of saxitoxin (STX) and tetrodotoxin (TTX) analogs are guanidinium alkaloids that share a common high affinity Q1 Q2 and ion flux blockage capacity for voltage-gated sodium ion channels (Nav). Members of the STX group, also known as paralytic shellfish toxins (PST), are produced among three genera of marine dinof...

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the detection and quantitation of karlotoxins in the selected reaction monitoring (SRM) mode. This novel method was based upon the analysis of purified karlotoxins (KcTx-1, KmTx-2, 44-oxo-KmTx-2, KmTx-5), one amphidinol (AM-18), and unpurified extracts of bulk cult...

Guanidinium toxins, such as saxitoxin (STX), tetrodotoxin (TTX) and their analogs, are naturally occurring alkaloids with divergent evolutionary origins and biogeographical distribution, but which share the common chemical feature of guanidinium moieties. These guanidinium groups confer high biological activity with high affinity and ion flux block...

The chain-forming marine dinoflagellate Gymnodinium catenatum Graham has a remarkable capacity to produce a wide array of neurotoxic alkaloids associated with Paralytic Shellfish Poisoning (PSP). More than a decade ago, a completely new group of benzoyl saxitoxin analogs produced exclusively by this species was discovered, but the exact structural...

In the Argentine Sea, blooms of toxigenic dinoflagellates of the Alexandrium tamarense species complex have led to fish and bird mortalities and human deaths as a consequence of paralytic shellfish poisoning (PSP). Yet little is known about the occurrence of other toxigenic species of the genus Alexandrium, or of their toxin composition beyond coas...

Harmful algal blooms (HABs) are natural phenomena that result from the interplay of biological, chemical, physical, and sedimentary processes occurring at different temporal and spatial scales. This paper provides an integrated description of HAB dynamics occurring at the mesoscale (10–100 km, sensu Haury et al., 1978) in confined and semi-confined...

Arctic regions have experienced pronounced biological and biophysical transformations as a result of global change processes over the last several decades. Current hypotheses propose an elevated impact of those environmental changes on the biodiversity, community composition and metabolic processes of species. The effects on ecosystem function and...

Proceedings of OECD Symposium on Aquatic Biotechnology and Food Safety

Saxitoxin (STX) and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav), impeding passage of Na+ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of s...

Populations of the toxigenic marine dinoflagellate Alexandrium are composed of multiple genotypes that display phenotypic variation for traits known to influence top-down processes, such as the ability to lyse co-occurring competitors and prospective grazers. We performed a detailed molecular analysis of species interactions to determine how differ...

The bloom-forming dinoflagellate Alexandrium fundyense has been extensively studied due its toxin-producing capabilities and consequent impacts on human health and eco- nomies. This study investigated the prevalence of resting cysts of A. fundyense in western Green- land and Iceland, to assess the historical presence and magnitude of bloom populati...

The third leg MSM21/3 of the MARIA S. MERIAN cruise, known under the acronym ARCHEMHAB, was a component of the Core Research Project on Harmful Algal Blooms in Fjords and Coastal Embayments within the SCOR|IOC program GEOHAB. This field campaign extended previous work in the North Atlantic and North Sea, in a comparative study of the west coasts of...

Bioinformatics, simulations for toxicity

Background Unicellular dinoflagellates are an important group of primary producers within the marine plankton community. Many of these species are capable of forming harmful algae blooms (HABs) and of producing potent phycotoxins, thereby causing deleterious impacts on their environment and posing a threat to human health. The recently discovered t...

The paralytic shellfish toxin (PST) profiles of Gymnodinium catenatum Graham have been reported for several isolates from the Pacific coast of Mexico cultured under different laboratory conditions, as well as from natural populations. Up to 15 saxitoxin analogues occurred and the quantity of each toxin depended on the growth phase and culture condi...

A unialgal culture of a Pseudo-nitzschia species dominant in the plankton of Algoa Bay in the spring of 2012 was established by isolation of clonal chains of cells. Identification of the species as Pseudo-nitzschia multiseries was based on frustule morphometrics provided by light and scanning electron microscopy, and confirmed by phylogenetic analy...

Different environmental nitrogen sources play selective roles in the development of cyanobacterial blooms and noxious effects are often exacerbated when toxic cyanobacteria are dominant. Cylindrospermopsis raciborskii CS-505 (heterocystous, nitrogen fixing) and Raphidiopsis brookii D9 (non-N2 fixing) produce the nitrogenous toxins cylindrospermopsi...

Alfacs and Fangar bays are semi-enclosed embayments in the Ebro Delta system, where sustainable shellfish aquaculture requires harmful algal bloom (HAB) surveillance at the appropriate spatio-temporal scale. We therefore deployed a hyperspectral light-field observational system in Alfacs Bay, in late spring through summer over two successive years....

The surveillance of harmful algal blooms (HABs) in aquatic environments is a crucial component in monitoring and mitigation of adverse effects caused by accumulation of high biomass of algal cells and/or associated toxins. The high diversity among HABs necessitates observational approaches that cover a broad spectrum of temporal and spatial scales....

Harmful algal blooms (HABs) are characterized by proliferation of algae, causing harmful effects to aquatic ecosystems or to human health. High taxonomic diversity and multiple phylogenetic origins complicate identification of common ecological and evolutionary strategies and thus predictions on global change consequences. Variation estimates revea...

From the German Bight along Jutland to the western Skagerrak, we found representatives of almost all groups of phycotoxins known to occur in North Sea plankton. Identification was by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in plankton size fractions, with domoic acid and 20-me G the most abundant toxins. The dominance o...

Two oceanographic surveys for toxigenic phytoplankton in the South and North Atlantic Ocean, including the adjacent Irminger Sea and the Arctic coasts of Greenland and Iceland, were conducted for analysis of putative toxic microalgal species and their respective toxins. During both expeditions, plankton was sampled by phytoplankton net (20 µm mesh)...

Molecular methods provide promising tools for routine detection and quantification of toxic microalgae in plankton samples. To this end, novel TaqMan minor groove binding probes and primers targeting the small (SSU) or large (LSU) ribosomal subunit (rRNA) were developed for two species of the marine dinoflagellate genus Alexandrium (A. minutum, A....

We analysed the molecular and morphological features of strains of Chattonella subsalsa isolated from the western Adriatic coast (Mediterranean Sea), with the aim of confirming their classification and elucidating their phylogenetic positions within the Raphidophyceae. We sequenced parts of the ribosomal operon, including the small subunit (SSU), t...

Molecular probes were developed for the dinoflagellate genus Azadinium to discriminate among three taxa difficult to differentiate by light microscopy. This genus contains azaspiracid toxin-producing Azadinium spinosum, but also non-toxigenic species. Quantitative polymerase chain reaction (qPCR) and fluorescence in situ hybridization (FISH) assays...

The variability of toxigenic phytoplankton and the consequent uptake and loss of toxins by the mussel Choromytilus meridionalis was investigated in the southern Benguela at the event scale (3–10 days) in response to the upwelling–downwelling cycle. Phytoplankton and mussel samples were collected daily (20 March–11 April 2007) from a mooring station...

Bivalve suspension-feeding can produce horizontal gradients of particulate suspended matter, or seston, which may impair bivalve growth among other impacts to the coastal ecosystem. We proposed a method to assess the concentration of seston at different locations along a shellfish farm by means of measurements of the depth-averaged diffuse attenuat...

Detection of paralytic shellfish poisoning (PSP) toxins in scallops from the west coast of Greenland exceeding the 800 μg toxin/kg shellfish limit led to an investigation with the aim of finding the responsible organism(s). Three strains of Alexandrium Halim were established from single cell isolations. Morphological identification of the strains a...

The ichthyotoxic and mixotrophic prymnesiophyte Prymnesium parvum is known to produce dense virtually monospecific blooms in marine coastal, brackish, and inshore waters. Fish-killing Pyrmnesium blooms are often associated with macronutrient imbalanced conditions based upon shifts in ambient nitrogen (N):phosphorus (P) ratios. We therefore investig...

The dinoflagellate genus Alexandrium is one of the major harmful algal bloom (HAB) genera with respect to the diversity, magnitude and consequences of blooms. The ability of Alexandrium to colonize multiple habitats and to persist over large regions through time is testimony to the adaptability and resilience of this group of species. Three differe...

The public health, tourism, fisheries, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past few decades. This has led to heightened scientific and regulatory attention, and the development of many new technologies and approaches for research and management. This, in turn, is leading to significant paradigm shifts...

The public health, tourism, fisheries, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past few decades. This has led to heightened scientific and regulatory attention, and the development of many new technologies and approaches for research and management. This, in turn, is leading to significant paradigm shifts...

Fosmid library contig list with annotations. (XLS)

Gel electrophoresis of restriction digested fosmid clones. (XLS)

Overview of stop codon usages in dinoflgellate and other chromalveolates. (XLS)

The complete SL-containing EST sets of A. ostenfeldii , A. minutum , A. catenella and A. tamarense . (FAS)

BAC library contig list with annotations. (XLS)

Overview of RepeatMasker results of A. ostenfeldii genomic sequences (BAC and fosmid data combined). (TIF)

Alignment of repeat motif 1, 3, and 4. (XLS)

Overview of RepeatMasker results of one completely sequenced fosmid clone. (TIF)

Many dinoflagellate species are notorious for the toxins they produce and ecological and human health consequences associated with harmful algal blooms (HABs). Dinoflagellates are particularly refractory to genomic analysis due to the enormous genome size, lack of knowledge about their DNA composition and structure, and peculiarities of gene regula...

The toxigenic marine dinoflagellate Alexandrium minutum forms toxic blooms causing paralytic shellfish poisoning (PSP), primarily in coastal waters, throughout the world. We examined effects on physiology and gene expression patterns associated with growth and nutrient starvation in a toxic strain of A. minutum. Bloom-relevant factors, including gr...