Pseudo-nitzschia in New Zealand and the role of DNA probes and immunoassays in refining marine biotoxin monitoring programmes

Domoic acid (DA) was first detected in shellfish in New Zealand after the implementation of a comprehensive biotoxin monitoring programme for amnesic, paralytic, diarrhetic and neurotoxic shellfish toxins, following a suspected neurotoxic shellfish poisoning (NSP) event in early 1993. Both phytoplankton monitoring and shellfish flesh testing programmes have led to an extensive database which has helped link species of Pseudo-nitzschia to specific DA outbreaks. In 1994, P. pungens and P. turgidula were associated with DA contamination of shellfish, and cultured isolates of these species proved to be toxin producers. During 1996 the use of species-specific ribosomal RNA (rRNA)-targeted oligonucleotide probes and DA immunoassays led to the discovery of toxin production by P. fraudulenta, and showed the nontoxic P. heimii to be a major bloom former. Pseudo-nitzschia delicatissima, P. pseudodelicatissima and P. multiseries, also identified using rRNA-targeted probes, have been linked to DA contamination of New Zealand shellfish; P. australis is the main cause of DA in scallops. The relative amnesic shellfish poisoning (ASP) risk associated with different species, largely determined by DA immunoassays of cultured isolates, is now used by some regulators to refine risk assessments. Species identification is therefore vital so that shellfish growers, and health and industry officials, can make safe and economically sound harvesting decisions. The development and field trialling of DNA probes is proving invaluable in this context.     

Biosynthesis of domoic acid by the diatom Pseudo-nitzschia multiseries

The biosynthesis of the neurotoxin domoic acid (DA) in the diatom Pseudo-nitzschia multiseries was investigated using 13C- and 14C-labelled precursors. The labelling pattern determined by NMR spectroscopy following incorporation of [1,2-13C2]-acetate showed enrichment of every carbon of DA. The enrichment levels were consistent with a biosynthetic pathway involving two different intermediate precursor units. Addition of labelled acetate either early or late during exponential growth gave similar patterns and levels of incorporation. Analysis of the labelling pattern indicated that DA is biosynthesised by condensation of an isoprenoid intermediate with another intermediate derived from the tricarboxylic acid (TCA) cycle. The absence of deuterium at C2 in DA following incorporation of [2-13C, 2H3]-acetate is consistent with alpha-ketoglutarate or a derivative as the TCA cycle-derived intermediate. The different incorporation efficiencies of acetate into the putative precursor intermediates suggest that either each unit is biosynthesized in a different part of the diatom cell, or that the isoprene chain is not assembled by the usual acetate-mevalonate pathway. The latter proposal is supported by the complete absence of deuterium retention in the isoprenoid-derived portion following incorporation of [2-13C, 2H3]-acetate.     

Inorganic carbon acquisition in potentially toxic and non-toxic diatoms: the effect of pH-induced changes in seawater carbonate chemistry

The effects of pH-induced changes in seawater carbonate chemistry on inorganic carbon (C(i)) acquisition and domoic acid (DA) production were studied in two potentially toxic diatom species, Pseudo-nitzschia multiseries and Nitzschia navis-varingica, and the non-toxic Stellarima stellaris. In vivo activities of carbonic anhydrase (CA), photosynthetic O(2) evolution and CO(2) and HCO(3)(-) uptake rates were measured by membrane inlet MS in cells acclimated to low (7.9) and high pH (8.4 or 8.9). Species-specific differences in the mode of carbon acquisition were found. While extracellular carbonic anhydrase (eCA) activities increased with pH in P. multiseries and S. stellaris, N. navis-varingica exhibited low eCA activities independent of pH. Half-saturation concentrations (K(1/2)) for photosynthetic O(2) evolution, which were highest in S. stellaris and lowest in P. multiseries, generally decreased with increasing pH. In terms of carbon source, all species took up both CO(2) and HCO(3)(-). K(1/2) values for inorganic carbon uptake decreased with increasing pH in two species, while in N. navis-varingica apparent affinities did not change. While the contribution of HCO(3)(-) to net fixation was more than 85% in S. stellaris, it was about 55% in P. multiseries and only approximately 30% in N. navis-varingica. The intracellular content of DA increased in P. multiseries and N. navis-varingica with increasing pH. Based on our data, we propose a novel role for eCA acting as C(i)-recycling mechanism. With regard to pH-dependence of growth, the 'HCO(3)(-) user' S. stellaris was as sensitive as the 'CO(2) user' N. navis-varingica. The suggested relationship between DA and carbon acquisition/C(i) limitation could not be confirmed.     

CHANGES IN DOMOIC ACID PRODUCTION AND CELLULAR CHEMICAL COMPOSITION OF THE TOXIGENIC DIATOM PSEUDO-NITZSCHIA MULTISERIES UNDER PHOSPHATE LIMITATION1

Production of domoic acid (DA), a neurotoxin, by the diatom Pseudo-nitzschia multiseries (previously Nitzschia pungens f. multiseries) Hasle and its cellular chemical composition were studied in phosphate-limited chemostat continuous cultures and in subsequent batch cultures. Under steady-state chemostat conditions, DA production increased from 0.01 to 0.26 pg DA · cell^?1· d^?1 as the growth rate decreased. When the nutrient supply was discontinued (to produce a batch culture), DA production was enhanced by a factor of ca. 3. DA production was temporarily suspended upon addition of phosphate to the batch cultures but resumed 1 d later at a higher rate coincident with the decline of phosphate uptake. In both steady-state continuous culture and batch culture, more DA was produced when alkaline phosphatase activity (APA) was high. The association of high DA production with high levels of APA and high cellular N:P ratios strongly suggests that phosphate limitation enhances DA production. Also, DA production was high when other primary metabolism (e.g. uptake of carbon, nitrogen, phosphorus and silicon, and cell division) was low, but chlorophyll a and adenosine triphosphate were generally high. This suggests that the synthesis of DA requires a substantial amount of biogenic energy.     

PSEUDO-NITZSCHIA SPECIES (BACILLARIOPHYCEAE) IN LOUISIANA COASTAL WATERS: MOLECULAR PROBE FIELD TRIALS, GENETIC VARIABILITY, AND DOMOIC ACID ANALYSES

An 18-month field survey of the Pseudo-nitzschia population present in Louisiana coastal waters was conducted comparing species abundance estimates by novel fluorescent molecular probes (16S large subunit rDNA oligonucleotide sequences) with traditional electron and differential-interference light microscopy. While the probe and microscopic analyses agreed on the presence or absence of four common Pseudo-nitzschia species ( P. multiseries (Hasle) Hasle, P. pseudodelicatissima (Hasle) Hasle, P. delicatissima (P.T. Cleve) Heiden, and P. pungens (Grunow) Hasle in 66% of the samples analyzed, the probes gave conflicting results with the microscopic methods in the remaining 34% of the samples. The majority of the discrepancies appear to be because of genetic variation within the Pseudo-nitzschia population, especially in P. pseudodelicatissima, indicating that the Monterey Bay Pseudo-nitzschia spp. may not be appropriate reference strains for distinguishing Louisiana Pseudo-nitzschia spp. Additionally, P. pseudodelicatissima has been associated with domoic acid (DA) activity in three field samples, at levels up to 22 times higher than the highest value given inother published reports of DA production by this species. The contemporaneous existence of multiple strains of P. pseudodelicatissima (toxic and non-toxic) presents new challenges to the study of the ecophysiology and population dynamics of this bloom-forming species.     

GROWTH AND DOMOIC ACID PRODUCTION BY PSEUDO‐NITZSCHIA SERIATA (BACILLARIOPHYCEAE) UNDER PHOSPHATE AND SILICATE LIMITATION1

Pseudo‐nitzschia seriata (Cleve) H. Peragallo isolated from Scottish west coast waters was studied in batch culture with phosphate (P) or silicate (Si) as the yield‐limiting nutrient at 15°C. This species produced the neurotoxin domoic acid (DA) when either nutrient was limiting but produced more when stressed by Si limitation during the stationary phase. Under P‐limiting conditions, exponential growth stopped after P was reduced to a low threshold concentration. Under Si‐limiting conditions, fast exponential growth was followed by a period of slower exponential growth, until Si became exhausted. A stationary phase was observed in the P‐limited but not the Si‐limited cultures, the latter showing a rapid decrease in cell density after the second exponential growth phase. Si‐limited cultures exhibited a further period of active metabolism (as indicated by increases in chl and carbon per cell) late in the experiment, presumably fueled by regenerated Si. DA production was low in exponential phase under both conditions. In P‐limited cultures, most DA was produced during the immediate postexponential phase, with little or no new DA produced during later cell senescence. In contrast, although a substantial amount of DA was produced during the slower exponential phase of the Si‐limited cultures, DA production was even greater near the end of the experiment, coincident with the period of chl synthesis and increase in carbon biomass. Comparison of the magnitude of toxin production in the two nutrient regimes indicated a greater threat of P. seriata‐generated amnesic shellfish poisoning events under Si rather than P nutrient limitation.     

DOMOIC ACID PRODUCTION IN NITZSCHIA SP. (BACILLARIOPHYCEAE) ISOLATED FROM A SHRIMP-CULTURE POND IN DO SON, VIETNAM

Domoic acid (DA), a neuroexcitatory amino acid, was detected in batch culture of the newly recognized species Nitzschia navis-varingica Lundholm et Moestrup . The production of DA by this diatom was confirmed by electrospray ionization mass spectrometry. The diatom was collected from a shrimp-culture pond in Do Son, Vietnam. The production of DA (1.7 pg·cell ^{− 1}) is within the levels reported for Pseudo-nitzschia multiseries (Hasle) Hasle. The DA production started during the late exponential growth phase and reached a maximum during the early stationary growth phase. Maximum DA levels in the axenic culture decreased to about half that of the nonaxenic culture (0.9 pg·cell ^{− 1} vs. 1.7 pg·cell ^{− 1}), suggesting that DA production by the new species is influenced by bacteria.     

THE UBIQUITOUS PRESENCE OF CHLOROPHYLL D IN RED ALGAE FROM THE MONTEREY PENINSULA

Domoic acid (DA) is a neurotoxic amino acid produced by several members of the diatom genus Pseudo-nitzschia. Trophic transfer of DA up the food chain has been implicated in the deaths of 100's of marine birds and marine mammals along the central California Coast. The physiological function of DA in Pseudo-nitzschia spp. has not been defined, although some evidence indicates that elevated metal concentrations can induce DA accumulation (Subba RAO et al. , 1998, P.S.Z.N. Mar. Ecol. 19:31). Although California coastal waters have experienced a decline in several heavy metals from 1977–1990, copper concentrations have increased by as much as 25% (Stephenson, M. D. & Leonard, G. H., 1994, Mar. Poll. Bull. 28:148). Many algae produce chelators, including amino acids, in response to toxic [Cu²+] (Wu et al. 1998, J. Phycol. 34: 113). Domoic acid, a tricarboxylic acid, has 4 functional groups that may readily form chelation complexes with transition metals like copper. Copper enrichment experiments indicate that while Cu²+ is toxic to Pseudo-nitzschia multiseries at total [Cu] greater than 16.1μM (pCu 6.0), intracellular DA accumulation increases up to this point with no decline in growth rates relative to cultures grown in standard enriched seawater. These data suggest that DA may be accumulated by P. multiseries to mitigate the toxicity of elevated [Cu²+]. Chemiluminescence will be used to quantify the binding affinity (expressed as conditional stability constants, Kc) of DA for Cu²+. Defining the Cu-DA dose response relationship in Pseudo-nitzschia can facilitate prediction of future toxic bloom events.     

DNA PROBES AND A RECEPTOR-BINDING ASSAY FOR DETECTION OF PSEUDO-NITZSCHIA (BACILLARIOPHYCEAE) SPECIES AND DOMOIC ACID ACTIVITY IN CULTURED AND NATURAL SAMPLES

Large-subunit ribosomal RNA-targeted probes for Pseudo-nitzschia australis Frenguelli, P. multiseries (Hasle) Hasle, P. pseudodelicatissima (Hasle) Hasle, and P. pungens (Grunow) Hasle were applied to cultured and natural samples using whole-cell and sandwich hybridization. Testing of the latter method is emphasized here, and technique refinements that took place during 1996–1997 are documented. Application of the sandwich hybridization test showed that the signal intensity obtained for a given number of target cells remained constant as batch cultures of these organisms progressed from active through stationary growth phases. This suggests that cellular rRNA content for each target species remained relatively stable despite changes in growth state. Application of whole-cell and sandwich hybridization assays to natural samples showed that both methods could be used to detect wild P. australis, P. pseudodelicatissima, and to a lesser degree P. multiseries, but detection of P. pungens was prone to error. A receptor-binding assay for domoic acid (DA) enabled detection of this toxin activity associated with a particulate fraction of the plankton and provided a context in which to view results of the rRNA probe tests. In one case, the probe for P. australis cross-reacted with P. cf. delicatissima. The sample that contained the latter species also contained a low amount of DA activity. Under certain field conditions, results of whole-cell and sandwich hybridization tests disagreed. Detailed analysis of selected field samples illustrates how such situations arose. Collectively, the rRNA probe and toxin analyses suggest that manifestation of DA in the environment is possible in the absence of readily recognizable intact cells.     

INFLUENCE OF PHOSPHORUS LIMITATION ON TOXICITY AND PHOTOSYNTHESIS OF ALEXANDRIUM MINUTUM (DINOPHYCEAE) MONITORED BY IN‐LINE DETECTION OF VARIABLE CHLOROPHYLL FLUORESCENCE1

The effects of phosphorus (P) limitation on growth, toxicity, and variable chl fluorescence of Alexandrium minutum were examined in batch culture experiments. Cell division was greatly impaired in P‐limited cultures, but P spiking of these cultures after 9 days stimulated high levels of cell division equivalent to P‐replete cultures. The cellular concentration of paralytic shellfish toxins was consistent over the growth cycle of control cultures from lag phase into logarithmic growth phase, with toxins repeatedly lost to daughter cells during division. The low level of cell division in P‐limited cultures resulted in a 10‐fold increase of cellular toxin compared with controls, but this dropped upon P spiking due to increased rates of cell division. The history of phosphorus supply had an important effect on toxin concentration, with the P‐limited and the P‐spiked cultures showing values 2‐fold higher than the P‐replete cultures. Toxin profiles of the A. minutum strain used in these experiments were dominated by the N₁‐hydroxy toxins, gonyautoxins (GTX) GTX1 and GTX4, which were approximately 40 times more abundant than their analogues, GTX2 and GTX3, in P‐limited cultures. The dominance of the N₁‐hydroxy toxins increased significantly in control cultures as they advanced through logarithmic growth. In‐line measurements of the variable chl fluorescence of light‐adapted cells indicated consistent photochemical efficiency under P‐replete conditions. P limitation induced a drop in fluorescence‐based photochemical efficiency that was reversible by P spiking. There was an inverse linear relationship between in‐line fluorescence and cell toxin quota (r = ?0.88). Monitoring fluorescence in‐line may be valuable in managing efficient biotechnological production of toxins.     

High CO2 and silicate limitation synergistically increase the toxicity of Pseudo-nitzschia fraudulenta

Anthropogenic CO(2) is progressively acidifying the ocean, but the responses of harmful algal bloom species that produce toxins that can bioaccumulate remain virtually unknown. The neurotoxin domoic acid is produced by the globally-distributed diatom genus Pseudo-nitzschia. This toxin is responsible for amnesic shellfish poisoning, which can result in illness or death in humans and regularly causes mass mortalities of marine mammals and birds. Domoic acid production by Pseudo-nitzschia cells is known to be regulated by nutrient availability, but potential interactions with increasing seawater CO(2) concentrations are poorly understood. Here we present experiments measuring domoic acid production by acclimatized cultures of Pseudo-nitzschia fraudulenta that demonstrate a strong synergism between projected future CO(2) levels (765 ppm) and silicate-limited growth, which greatly increases cellular toxicity relative to growth under modern atmospheric (360 ppm) or pre-industrial (200 ppm) CO(2) conditions. Cellular Si:C ratios decrease with increasing CO(2), in a trend opposite to that seen for domoic acid production. The coastal California upwelling system where this species was isolated currently exhibits rapidly increasing levels of anthropogenic acidification, as well as widespread episodic silicate limitation of diatom growth. Our results suggest that the current ecosystem and human health impacts of toxic Pseudo-nitzschia blooms could be greatly exacerbated by future ocean acidification and 'carbon fertilization' of the coastal ocean.     

Coupling of saxitoxin biosynthesis to the G1 phase of the cell cycle in the dinoflagellate Alexandrin fundyense: temperature and nutrient effects

The correlation between changes in length of the different cell cycle stages and the toxicity of Alexandrium fundyense Balech was studied in semi-continuous cultures. Growth rates ranging from 0.031 d(-1) to 0.36 d(-1) were established at different temperatures or levels of phosphate limitation. In all treatments, G1 was the phase with the longest duration. Decrease in growth rate was associated with an increase in duration of the different cell cycle stages. Toxin content was always directly correlated to the duration of the G1 phase. In both the temperature treatments and the phosphate limitation experiments, toxin production rates remained constant for the respective range of conditions, implying that the variations in toxin content observed were a result of increasing periods of biosynthetic activity. Toxin accumulation was directly correlated to protein biosynthesis in all temperature treatments. In contrast, toxin content showed little correlation with protein content as phosphate limitation increased. Significant differences in toxin composition were observed between the temperature and phosphate treatments. Total concentrations of GTX II and III and C I and II were significantly higher in the phosphate-limited cultures, while the levels of STX, NEO and gonyautoxins I and IV remained virtually unchanged. We conclude that toxin biosynthesis in A. fundyense is coupled to the G1 phase of the cell cycle, that toxin synthesis is not down-regulated by phosphate deprivation and that interconversions among saxitoxin derivatives are influenced by the availability of phosphate.     

Acclimation of the Marine Diatom Pseudo-nitzschia australis to Different Salinity Conditions: Effects on Growth,Photosynthetic Activity,and Domoic Acid Content1

Toxic Pseudo-nitzschia australis strains isolated from French coastal waters were studied to investigate their capacity to adapt to different salinities. Their acclimation to different salinity conditions (10, 20, 30, 35, and 40) was studied on growth, photosynthetic capacity, cell biovolume, and domoic acid (DA) content. The strains showed an ability to acclimate to a salinity range from 20 to 40, with optimal growth rates between salinities 30 and 40. The highest cell biovolume was observed at the lowest salinity 20 and was associated with the lowest growth rate. Salinity did not affect the photosynthetic activity; F_v/F_m values and the pigment contents remained high with no significant difference among salinities. An enhanced production of zeaxanthin was, however, observed in the late stationary and decline phases in all cultures except for those acclimated to salinity 20. In terms of cellular toxin content, DA concentrations were 2 to 3-fold higher at the lowest salinity (20) than at the other salinities and were combined with a low amount of dissolved DA. The fact that P. australis accumulate more DA per cell in less saline waters, illustrates that climate-related changes in salinity may affect Pseudo-nitzschia physiology through direct effects on growth, physiology, and toxin content.     

中国沿海新报道的三种产毒拟菱形藻

为了明确我国海域拟菱形藻属(Pseudo-nitzschia)物种的产毒特征, 从中国沿海建立了15个拟菱形藻单克隆培养株系, 利用高效液相色谱-质谱联用法对其多莫酸特征进行检测, 在10个株系中检测到多莫酸。结合光学显微镜下的群体特征和透射电镜下的超微形态学特征, 以及基于核糖体转录间隔区的分子系统学数据, 确认上述10个产毒株系分别隶属于3个物种:尖细拟菱形藻P. cuspidata、伪柔弱拟菱形藻P. pseudodelicatissima、伪善拟菱形藻P. fraudulenta, 其中伪善拟菱形藻是我国的新记录种。建立尖细拟菱形藻的11个尖细拟菱形藻株系, 其中3个株系未检出多莫酸, 其余8个株系有检出, 单细胞产毒水平为0.4—5.5 fg。建立伪柔弱拟菱形藻株系2个, 1个未检出多莫酸, 另1个株系的单细胞产毒量为1 fg。建立伪善拟菱形藻株系2个, 纯种培养株系均未检出多莫酸。利用卤虫(Artemia salina)对部分藻株进行混培诱导, 其中尖细拟菱形藻(MC4049)和伪柔弱拟菱形藻(MC3015)的产毒水平略有下降, 单细胞产毒水平分别由2、1 fg降至0.2、0.4 fg, 而伪善拟菱形藻(MC4074)的产毒能力则有显著改变, 单细胞产毒水平由未检出上升至17.5 fg。研究丰富了我国产毒拟菱形藻的物种多样性, 明确了其物种信息和产毒水平, 可为后续深入研究提供基础数据。     

Factors controlling the production of domoic acid by Pseudo-nitzschia (Bacillariophyceae): A model study

A mechanistic model has been developed to explore the factors controlling the production of domoic acid (DA) by the pennate diatom Pseudo-nitzschia. The idealized model allows consideration of the uncoupling between photosynthesis and growth, while DA production has been set as a secondary metabolism sharing common precursors with growth. Under growth limitation, these precursors can accumulate, resulting in an increased DA production. The model was first evaluated based on its ability to simulate the observed DA production by either silicon (Si) or phosphorus (P) limited batch cultures of Pseudo-nitzschia available in the literature. Sensitivity tests were further performed to explore how the ambient nutrients and the light regime (intensity and photoperiod length) are possibly directing the Pseudo-nitzschia toxicity. The general pattern that emerged is that excess light, in combination with Si or P limitation, favours DA production, provided nitrogen (N) is sufficient. Model simulations with varying nutrient stocks supporting Pseudo-nitzschia blooms under non-limiting light suggest two potential ways for nutrients to control DA production. First, N excess in comparison to available Si and P relieves DA production from its limitation by N, an absolute requirement of the DA molecule. Second, increased nutrient stocks amplify the DA production phase of the blooms (in addition to enhancing Pseudo-nitzschia biomass) which leads to an even more toxigenic bloom. Simulations investigating the light regime suggest a light threshold below which an important delay in DA production could be expected in Pseudo-nitzschia cultures. In the natural environment, the monitoring of light conditions during Pseudo-nitzschia blooms might help to anticipate the magnitude of the toxic event. Pseudo-nitzschia toxicity is indeed linked to the excess of primary carbon that accumulates during photosynthesis under growth limitation by nutrients.     

PSEUDO-NITZSCHIA PUNGENS AND P. MULTISERIES (BACILLARIOPHYCEAE): NOMENCLATURAL HISTORY,MORPHOLOGY, AND DISTRIBUTION1

Pseudo-nitzschia pungens f: multiseries is raised in rank from form to species based on morphological, physiological, and genetic features. Distinctive details of the valve face striae, the valve mantle, and the girdle of P. pungens and P. multiseries are outlined. The nomenclatural history and the distribution of the two species and their relationship to other species of the genus are discussed.     

Time-scale dynamics of proteome predicts the central carbon metabolism involved in triterpenoid accumulation responsive to nitrogen limitation in Ganoderma lucidum

Central carbon metabolism describes the integration of transport pathway of main carbon sources inside the cell. Nitrogen (N) limitation is a favorable approach to stimulate ganoderic triterpenoid (GT) accumulation in Ganoderma lucidum. In this study, the dynamic regulation of metabolism reassignment towards GT biosynthesis responsive to N limitation was investigated by iTRAQ-based proteome. Physiological data suggested that N limitation slightly affected cell growth but significantly enhanced GT contents in the initial 20 days. From day 10, the protein contents were halted by prolonged N limitation duration. Proteomics-based investigations revealed that the carbon skeletons integrated into GT precursors were regenerated by glycolysis and the tricarboxylic acid (TCA) cycle. Cells strategically reserved nitrogen by barely incorporating it into TCA cycle intermediates to form amino acids, and enzymes involved in protein degradation were up regulated. Furthermore, regulation of proteins in response to abiotic stress and oxidation– reduction processes played a critical role in maintaining cellular homeostasis. These findings indicated that the flux of carbon into GT following N deficiency was a consequence of the remodeling of intermediate metabolism in TCA cycle and glycolysis reactions. This study provides a rationale for genetic engineering of G. lucidum, which may enable synchronized biomass and GT synthesis.     

大亚湾水域并基拟菱形藻的种类鉴定和产毒特征分析

为了丰富我国海域拟菱形藻(Pseudo-nitzschia Peragallo)的物种多样性, 并澄清其产毒特征, 研究从广东大亚湾海域分离并建立了一株拟菱形藻的单克隆培养株系MC298, 通过光学显微镜下的群体特征和透射电镜下的超微形态特征观察, 结合基于核糖体转录间隔区(Internal Transcribed Spacer, ITS)的分子系统学数据, 以及基于ITS2转录RNA的二级结构分析, 鉴定到我国拟菱形藻属的1个新记录种: 并基拟菱形藻P. decipiens Lundholm & Moestrup。研究对其形态学特征进行了较为详细地描述, 并与相似种进行了比较, 还对其ITS2-RNA的特有标志结构进行了阐述。同时, 利用高效液相色谱-质谱联用法(Liquid chromatography tandem mass spectrometry, LC-MS/MS)对该藻株的产毒特征进行了检测, 结果未检测到DA的存在。研究不仅丰富了我国拟菱形藻属的物种多样性, 也可为拟菱形藻的产毒特征研究提供基础数据。