The presence of 12β-deoxydecarbamoylsaxitoxin in the Japanese toxic dinoflagellate Alexandrium determined by simultaneous analysis for paralytic shellfish toxins using HILIC-LC–MS/MS

A differential screening study using high-resolution (HR)-hydrophilic interaction chromatography (HILIC)-electrospray ionization (ESI)–quadrupole time-of-flight mass spectrometry (Q-TOF MS) was conducted to identify saxitoxin (STX) analogues in the marine dinoflagellate toxic sub-clone Alexandrium tamarense Axat-2 and the non-toxic sub-clone UAT-014-009 derived from the same Japanese isolate. One unknown compound was identified only in the toxic sub-clone and was found to have the molecular formula C₉H₁₆N₆O₂. This structure differed from that of decarbamoyl STX (dcSTX; C₉H₁₆N₆O₃) by the loss of a single oxygen. A 12-deoxy-dcSTX standard (a mixture of 12α- and β-deoxy-dcSTX) was chemically prepared from dcSTX by reduction with sodium borohydride. The unknown compound in the toxic strain of A. tamarense was identified as 12β-deoxy-dcSTX by comparison of its HR-HILIC-LC–MS retention time and HR–MS/MS spectrum with those of the chemically prepared standard, and the identification was confirmed by high-sensitivity HPLC analysis with post-column fluorescent derivatization. Moreover, two Japanese isolates of A. catenella showing toxin profiles different from that of A. tamarense were also found to contain 12β-deoxy-dcSTX. Previously, 12β-deoxy-dcSTX was isolated from the freshwater cyanobacterium Lyngbya wollei, which produces a unique set of STX analogues. This study is the first evidence of the presence of 12β-deoxy-dcSTX in marine dinoflagellates.     

Effects of calcium channel blockers and DCMU on motility and the photophobic response of Gyrodinium dorsum

The effects of the calcium channel blockers, verapamil, diltiazem and lanthanum ions and the Ca²⁺ dependency on motility as well as the photophobic response (stop-response) of Gyrodinium dorsum were studied. At Ca²⁺ concentrations below 10^-3 M, motility was inhibited. La³⁺ inhibits the stop-response, in contrast to verapamil and diltiazem. The only calcium channel blocker that increased the amount of non-motile cells was verapamil. The results indicate that motility are Ca²⁺ dependent and that the stop-responses of G. dorsum could be affected by extracellular Ca²⁺. Effects of the photosythesis inhibitor (DCMU) on the stop-response was also determined. With background light of different wavelength (614, 658 and 686 nm) the stop-response increased. DCMU inhibited this effect of background light. Negative results with the monoclonal antibody Pea-25 directed to phytochrome and the results with DCMU, indicate that the stop-response of G. dorsum is coupled to photosynthesis rather than to a phytochrome-like pigment. Oxygen evolution, but not cell movement, was completely inhibited by 10^-6 M DCMU.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-methylurea - DILT diltiazem - DMSO dimethylsulfoxide - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis - VER verapamil     

Toxicity and isolation of the cyanobacterium Nodularia spumigena from the southern Baltic Sea in 1986

Three water bloom samples were collected in August 1986 from the southern Baltic Sea. Acute toxicity of the samples was determined by mouse bioassay and the toxins were further studied by HPLC. The bloom samples contained equal amounts of cyanobacteria Nodularia spumigena and Aphanizomenon flos-aquae and were hepatotoxic. Two hepatotoxic Nodularia spumigena strains were isolated from the samples. The isolates produce a toxic peak indistinguishable from the bloom material in the HPLC analysis. The toxicity of the fractions was verified by mouse bioassay. Thus the toxicity of the bloom samples was in all likelihood caused by Nodularia spumigena.     

The distribution and temporal dynamics of the estuarine macroalgal community of San Francisco Bay

Long-term sampling of intertidal macroalgae along permanently marked transects within San Francisco Bay has shown a marked decline in overall species number along the estuarine gradient from the ocean to the river, presumably as a result of decreasing salinity and a progressive lack of hard substrata in the upstream direction. Green algae penetrated further landward than either brown or red species. Seasonally, macroalgal species diversity is lowest during the winter-spring months when salinity, temperature, and irradiance are at yearly minima. Macroalgal abundance as measured by percent cover was maximum during the late spring near the mouth of the estuary and during late summer towards the head. The seasonal increase in algal abundance is related to increasing salinity, temperature, and light availability to the bottom. The summer increase in irradiance is due to the longer photoperiod, increased frequency of day-time low tides, and reduced levels of suspended sediments. The aperiodic occurrence of algal blooms in San Pablo Bay may be caused by a combination of physical factors which are ultimately associated with the river inflow. A hypothesis based on interannual differences in river inflow and the contribution of phytoplankton to nutrient cycles in the benthos is presented to explain the occurrence of nuisance algal blooms.     

Some cytochemical studies on the cell surface ofAmphidinium carterae (Dinophyceae)

Summary The surface coat of the dinoflagellateAmphidinium carterae Hulburt was examined by fluorescence and transmission electron microscopy, using various fluorochromes and cationic dyes. The overall results showed cell-surface reactions typical of acid mucopolysaccharides. The cationic dye staining revealed an outer fine fibrillar layer (15–70 nm thick) overlying a dense anionic coat (40–60 nm thick) which appeared to thicken progressively with age. In general, the structure of the amphiesmal vesicles was similar to that previously described by other investigators. However, an acidic mucopolysaccharide layer was observed on the inner surface of these vesicles. Each of these structures is traversed by 1–3 pores and at least 2 types of extrusomes are formed, the spindle trichocysts and the mucocysts. Cell to cell adhesion through the surface coat was frequently observed. Evidence was also obtained for internalization of all the surface-coat markers used.This investigation forms part of a doctoral thesis submitted by the first author to the University of British Columbia, Vancouver, B.C.     

武汉东湖浮游植物各种成份分析与沉淀物中浮游植物活体碳、氮、磷的测定

本实验调查了武汉东湖浮游植物水华的各种成份以及水柱沉淀物内叶绿素α含量,根据碳与叶绿素α关系,给定了一回归方程,并计算出沉淀物中藻类活体相应的碳、氮、磷含量。从平均数值看,武汉东湖浮游植物水华的C,N,P含量分别为39.30,7.98及0.94(％);其干湿比为0.20,碳、氮比为5.10,碳、磷比为46.54,碳与叶绿素α之比则为133.32。 1983年东湖水柱沉淀物中浮游植物活体叶绿素α下沉量平均每天每平方米为43.8675微克(Ⅰ站)及35.5881微克(Ⅱ站)。利用东湖浮游植物水华各种成份含量及其各种比率计算出的东湖水柱沉淀物中浮游植物活体碳、氮、磷量,按顺序每天每平方米分别为2.53,0.50,0.05毫克(Ⅰ站)及2.09,0.41,0.04毫克(Ⅱ站)。     

Comparison of Suitability of Great Bay, New Jersey, and Parsonage Creek, New York, for Alexandrium tamarense

ABSTRACT. Alexandrium tamarense (Lebour) Balech (= Gonyaulax tamarensis Lebour) has been widely distributed and occasionally abundant in coastal waters of Long Island, New York in recent years. However, the distribution on the New Jersey coast has been sparse and this fact cannot be explained by this dinoflagellate's ability to migrate, or by its nutritional and physiological characteristics, or by the region's general suitability for phytoplankton. Therefore, the possibility that New Jersey coastal waters might be chemically exclusionary for A. tamarense seemed worth exploring. In a limited approach, we tested for water quality detrimental to the species in one New Jersey site (Great Bay) with a series of annual assays. Parsonage Creek, Long Island, New York, was assayed for comparison; this creek is assumed to have had at least marginal suitablity for A. tamarense , based on its reported long-term presence. Results provide tentative support for our working hypothesis, i.e. Great Bay chemical water quality is generally unfavorable for A. tamarense. Inhibition of A. tamarense growth, or culture decline, occurred in both assay series, but was substantially greater in Great Bay water. Inimical water quality was the most important factor distinguishing the two sites. Chelation with EDTA had greatest overall benefit in Great Bay assays, suggesting that lower availability of a natural chelator in the bay could be a secondary factor. Assay metal response is problematic, but we believe it permits speculation that essential metals could be partially limiting to A. tamarense in Great Bay, but would not be a critical regulator.     

Long-term changes in Noctiluca scintillans blooms along the Chinese coast from 1933 to 2020

Noctiluca scintillans is one of the most common harmful algal species and widely known due to its bioluminescence. In this study, the spatial distribution, seasonal variations, and long-term trends of N. scintillans blooms in China and the related drivers were analyzed and discussed. From 1933 to 2020, a total of 265 events of N. scintillans blooms were recorded in Chinese coastal waters, with a total duration of 1052 days. The first N. scintillans bloom occurred in Zhejiang in 1933, and only three events were recorded before 1980. From 1981 to 2020, N. scintillans caused harmful algal blooms (HABs) almost every year, both the average duration and the proportion of multiphase HABs showed an increasing trend. 1986–1992, 2002–2004, and 2009–2016 were the three peak periods with a frequency of no less than five events of N. scintillans blooms per year. In terms of spatial distribution, N. scintillans blooms spread from the Southeast China Sea to the Bohai Sea after 2000, Guangdong, Fujian, and Hebei were the three provinces with the highest numbers of recorded events of N. scintillans blooms. Moreover, 86.8% of the events of N. scintillans blooms occurred in spring (March, April, and May) and summer (June, July, and August). Among environmental factors, the dissolved inorganic phosphate, dissolved silicate and chemical oxygen demand were significantly correlated with the cell density of N. scintillans during N. scintillans blooms, and most of N. scintillans blooms were recorded in the temperature range of 18.0–25.0°C. Precipitation, hydrodynamics, water temperature, and food availability might be the main factors affecting the spatial–temporal distribution of N. scintillans blooms along the Chinese coast.     

The biology ofChlamydomyxa montana: Ultrastructure of the cyst

Summary Cells ofChlamydomyxa montana Lankester photosynthesize within a cyst under bright light and ingest diatoms in an excysted amoeboid form during periods of low light intensity. Cyst cell walls are partially comprised of cellulose and vary in thickness. The cells are multinucleate and intracellular bacteria are closely associated with the nuclei. A pair of centrioles is also present adjacent to individual nuclei. Chloroplasts are numerous and thylakoids are generally organized into bands of three. No endoplasmic reticulum was found surrounding the plastids, nor was a complete girdling lamella ever observed within.C. montana chloroplasts appear to be its own but this protist does not precisely fit into an algal class.