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Adult Pseudocalanus elongatus have been kept in the laboratory, and fed with a variety of algal grazing media. The survival under conditions of starvation has also been determined, and in this respect, the overwintering generation has been found to differ from other generations.Isochrysis galbana, Phaeodactylum tricornutum, Gymnodinium veneficum, G. vitiligo, Chlamydomonas sp. and C. coccoides have been found to be satisfactory foods for Pseudocalanus elongatusDicrateria inornata, Nitzschia gotlandica, Amphidinium sp., Chlorella stigmatophora and Dunaliella tertiolecta were found to be unsatisfactory foods for Pseudocalanus elongatus.

The effects of DDT (2,2-bis-( p -chlorophenyl)-1, 1, 1-trichloroethane) on the growth of seven marine phytoplankters, representative of five algal divisions, were studied. At a concentration of 80 parts per billion (0.23 μm) DDT, growth of Dunaliella tertiolecta was unaffected, and there was slight, if any, influence on the development of Cyclotella nana, Thalassiosira fluviatilis, Amphidinium carteri, Coccolithus huxleyi , and Porphyridium sp. Skeletonema costatum exhibited a 9 day lag before cell division commenced, the rate of growth subsequently being the same as in the control (no DDT). A further inoculation of this culture of S. costatum into 80 parts per billion DDT gave another 9-day lag before initiation of normal growth. The ability of marine phytoplankton to metabolize DDT varied. DDE (2,2-bis-( p -chlorophenyl)-1, 1-dichloroethylene) was the only significant hexane-soluble metabolite detected. It occurred in cells of S. costatum, C. nana, T. fluviatilis and D. tertiolecta . Maximum degree of conversion was 7.5% and was based on the total DDT found in the cell-water system of 9-day D. tertiolecta cultures. The total amount of DDT recovered from cultures in 2- to 3-week experiments ranged from 63.5% for T. fluviatilis to 90.7% for S. costatum . The amount of DDT found associated with the cells, collected by centrifugation, in the cell-water system ranged from 70.8 to 99.5%. Chloroplast particles were isolated from a “resistant” species, D. tertiolecta . Noncyclic electron flow, as measured by ferricyanide reduction, was inhibited by DDT and DDE, and could explain growth inhibition in other phytoplankters. Fifty percent inhibition occurred at 20 μm DDT. Sensitivity of phytoplankton to toxic hydrophobic chlorinated hydrocarbons may be dependent upon penetration of the molecules to active sites within membranes.

Fructose diphosphate aldolase activity was examined in acetone powders and cell-free extracts of 15 photoautotrophically grown marine planktonic species belonging to 6 algal divisions as follows: Chlorophyta: Tetraselmis maculata, Dunaliella tertiolecta; Chrysophyta: Monochrysis lutheri, Isochrysis galbana, Prymnesium parvum, Coccolithus huxleyi; Bacillariophyta: Phaeodactylum tricornutum, Skeletonema costatum, Cyclotella nana; Cryptophyta: Cryptomonas sp., Rhodomonas lens, Hemiselmis virescens; Pyrrophyta: Amphidinium carteri; Cyanophyta: Anacystis marina, Agmenellum quadruplicatum. Indications of the types of aldolase (Rutter's classes) present in each alga were obtained from comparative studies of the effects of pH and of the following reagents on the activity: ethylenediamine tetraacetate, dithiothreitol, p-chloromercuriphenyl sulfonate. Type I (higher plant-animal type) aldolase only was indicated in the 2 chlorophytes, in I chrys-ophyte (M. lutheri), and in 1 bacillariophyte (P. tricornutum), while the remaining algae appeared to contain either exclusively or principally Type II (bacterial-fungal type) aldolase. The evolutionary implications of these findings are discussed.

Thirty-one species of marine unicellular algae in pure culture were tested for survival in darkness at 20 C in seawater buffered at pH 7.6–7.8 and enriched with nitrate, orthophosphate, silicate, vitamins (B12, thiamin, biotin), and trace-metal ions (chelated with ethylenediamine tetraacetate). None of the species showed any significant growth in darkness but six species [including two cyanophytes, two chlorophytes (Nannochloris oculata, Tetraselmis maculata), one rhodophyte (Porphyridium cruentum), and one diatom (Phaeodactylum tricornutum)] resumed growth in light after 24 weeks in darkness (the maximum period tested). Another chlorophyte survived 18 weeks, two chrysomonads and one cryptomonad 12–14 weeks, and most other algae (including ten diatoms) 6–8 weeks of darkness. Skeletonema costatum, Hemiselmis virescens, Coccolithus huxleyi, and Amphidinium carteri showed the lowest survival potential ranging from one to three weeks. The observed darkness-survival may have ecological relevance to th...

A relatively rapid and sensitive method for the bioassay of seawater for dissolved biotin is described. The uptake of 14CO2 by cells of Amphidinium carteri in 2 h following a 94-h preincubation under carefully controlled conditions is proportional to biotin concentrations in seawater. Cell numbers can also be used to measure response to vitamin concentrations but the incubation time is extended to 144 or 168 h. The range of biotin concentrations capable of being assayed is 0.2–6.0 ng/l. These amounts are considerably less than those previously described.

A B S T R A C T The nucleus of the mesocaryotic dinoflagellate has unusually distinctive features as seen under the light and electron microscope. An electron microscope study of 7 species has demonstrated two kinds of dinoflagellate nuclei. One type, characteristic of Amphidinium and most other dinoflagellates and called here the dinocaryotic type, is distinguished by the presence of discrete chromosomes visible throughout the entire cell cycle. The other type, found in vegetative cells of Noctiluca and called here the nocticaryotic type, is characteristically devoid of evident chromosomes at least during interphase. Questions are raised regarding the distinction between the nucleoplasm, chromosomes, and nucleolus of dinoflagellates. As the Heliozoa and Radiolariahave typically eucaroytic nuclei, they should not be considered as part of the Mesocaryota, as has been previously suggested. THE CLASSIFICATION of all living organisms into two kingdoms is based on type of nuclear organization. Organisms with a well defined nucleus, containing chromosomes enveloped by a distinct nuclear envelope, are currently placed in the kindom Eucaryota. Organisms without discrete chromosomes and without a nuclear envelope are classified as belonging to the kingdom Procaryota. Bacteria and blue-green algae are considered procaryotic, whereas all other organisms

The biological and economic importance of the marine Dinoflagellata, as well as the unique taxonomic position of the group, call for a thorough investigation of their metabolic relations. As a preliminary to the wider problem presented by the planktonic genera, the shore-living forms are being studied with a view to determining their metabolic processes and the physical and biological factors which influence their relation to the general nexus of living forms in the tidal area. The present report deals with salinity as a determining factor in the distribution and photosynthetic activity of Amphidinium herdmani , Kofoid, one of the more abundant dinoflagellates in the Port Erin area. It is shown, experimentally, that the organisms, suspended in water and exposed to diffuse daylight, are capable of assimilating free carbon dioxide, at all salinities, from that of normal sea-water down to practically fresh-water. The rate of assimilation, however, is low when the salinity lies outside an optimal range (4 to 8 per mille), and it is possible that under these conditions Amphidinium may function, facultatively, as a heterotrophic organism. Determinations made upon samples of interstitial water, taken on the beach, demonstrate that salinity is a factor--there are doubtless others--in the distribution of Amphidinium , and that the strongly discoloured areas, where it is present in great profusion, are characterised by salinities lying within the optimal range indicated above.

1. The photosynthetic pigments of the brown symbiotic algae (zooxanthellae) isolated from five tridacnid clams and nine corals were found to be identical with the pigments of the dinoflagellate Amphidinium. Identifications were carried out by two-dimensional paper chromatography and by absorption spectrophotometry. Both zooxanthellae and dinoflagellates contained cholorphylls a and c, β-carotene, peridinin, neo-peridinin, dinoxanthin, neo-dinoxanthin, diadinoxanthin, and three minor xanthophyll fractions not previously described.2. Peridinin, crystallized from Tridacna gigas, or isolated by paper chromatography from Tridacna crocea, Pocillopora or the dinoflagellate Amphidinium, showed similar absorption characteristics in different solvents. The extinction coefficient of crystalline peridinin in acetone was E1 cm1% 1340.3. Clam zooxanthellae (and the dinoflagellates Amphidinium and Gymnodinium) contained a much higher proportion of chlorophyll c than coral zooxanthellae.4. No chlorophyll decomposition pr...

The taxonomic status of several well known species belonging to the genus Amphidinium (Dinophyceae) has been re-examined. Studies in culture and observations on the micro-anatomy of these organisms suggest that the number of species can be reduced to two, A. klebsii and A. carterae. They may be distinguished on the basis of fundamental differences in chloroplast morphology.

The occurrence of harmful epiphytic dinoflagellates is of concern to scientists, the aquaculture industry, and government due to their toxicity not only to marine organisms but also to humans. There have been no studies on the abundance of the epiphytic dinoflagellates in Korean waters. We explored the presence of epiphytic dinoflagellates in the coastal waters off Jeju Island, southwestern Korea. Furthermore, we measured the abundance of epiphytic dinoflagellates on the thalli of 24 different macroalgae, collected from five different locations in October 2009. Five epiphytic dinoflagellate genera Amphidinium, Coolia, Gambierdiscus, Ostreopsis, and Prorocentrum were found. These five genera were observed on the thalli of the macroalgae Chordaria flagelliformis, Martensia sp., Padina arborescens, and Sargassum sp., while none were observed exceptionally on Codium fragile. The abundance of Ostreopsis spp. was highest on Derbesia sp. (8,660 cells/g wet weight), while that of Gambierdiscus spp. was highest on Martensia sp. (4,870 cells/g-ww). The maximum abundances of Amphidinium spp., Coolia spp., and Prorocentrum spp. were 410, 710, and 300 cells/g-ww, respectively. The maximum abundance of Coolia spp., Gambierdiscus spp., and Ostreopsis spp. obtained in the present study was lower than for other locations reported in literature. The results of the present study suggest that the presence and abundance of epiphytic dinoflagellates may be related to the macroalgal species of the coastal waters of Jeju Island.

The dinoflagellate, Amphidinium wigrense, contains triple membrane-bound bodies we have termed "blue-green chloroplasts." We believe these chloroplasts were derived from a cryptomonad endosymbiont similar to that present in another blue-green dinoflagellate, Gymnodinium acidotum. These dinoflagellates provide evidence that a chloroplast has evolved from an endosymbiotic eukaryote.

Solitary radiolarians (Spongodrymus sp.) in laboratory cultures consumed 14C-labeled Amphidinium carteri and Coccolithus huxleyi more than Isochrysis galbana or Thalassiosira fluviatilis. The ratio of A. carteri protein consumed per unit time to the amount of Artemia sp. nauplius protein consumed (P/Z) was 6.7×10-2 indicating that these omnivorous radiolarians tend to consume more zooplankton protein than phytoplankton protein.

A population of the sand-dwelling dinoflagellate Amphidinium herdmaniae Kofoid & Swezy is described from the intertidal zone of Port Erin beach, Isle of Man. The population shows strong vertical migrations within the sand, which correlate with the tidal cycle. The control of timing of the migrations appears to be endogenous, but this control is weak, and is easily modified by environmental conditions in both the field and the laboratory. The modifying effects of rainfall and variations in light intensity are described. The migratory behaviour of the dinoflagellate is compared with that of the motile diatoms amongst which it occurs.

The mortality rate of female calanoid copepods Temora longicornis and Pseudocalanus elongatus was measured in relation to the concentration of different algae as a food source. Female copepods were fed either good-quality food (Rhodomonas sp.) or nutritionally poor food (Dunaliella sp., Amphidinium sp., Chrysochromulina polylepis and Synechococcus sp.) in high (>300 µg C l -1 ) or low (

Absolute stereochemistry of amphidinolides G and H, potent cytotoxic 27- and 26-membered macrolides, respectively, isolated from a marine dinoflagellate Amphidinium sp., was determined by X-ray diffraction analysis, synthesis of a degradation product, and chemical interconversion. Six new macrolides, amphidinolides H2~H5, G2, G3, and W, have been isolated from a marine dinoflagellate Amphidinium sp. (strain Y-42), and the structures were elucidated by 2D NMR data and chemical means. The structure-activity relationship of amphidinolide H-type macrolides for cytotoxicity was examined. The biosynthetic origins of amphidinolides B, C, H, J, T1, and W were investigated on the basis of 13C NMR data of 13C-enriched samples obtained by feeding experiments with [1-13C], [2-13C], and [1,2-13C2] sodium acetates in cultures of the dinoflagellates. Five novel long-chain polyhydroxyl compounds, colopsinols A~E, were obtained from the Amphidinium sp. (strain Y-5).

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Amphidinium lacustre Stein, non sensu auctt. was identified by reference to original descriptions, which differ significantly from later interpretations. Mixed cultures containing A. lacustre, cryptomonads, Spermatozopsis exsultans Korshikov, and small chlorelloid cells were examined for feeding events. The dinoflagellate ingested the cytoplasm of cryptomonads, leaving the periplast, and completely ingested Spermatozopsis and chlorelloid cells. A peduncle was used in the initial stages of prey capture, although it was not visible during food uptake. The ultrastructure of A. lacustre was typical of unarmored dinoflagellates. A single pusule per cell, consisting of one long, convoluted tube, opened directly into one of the flagellar canals. An eyespot was present, composed of presumably crystalline, vesicle-contained units, similar to those of Gymnodinium natalense Horiguchi et Pienaar. The main components of the flagellar apparatus resembled those of other Amphidinium species, but differences were noted. The transverse basal body overlapped the proximal end of the longitudinal one at an angle of about 120°. Three connectives were distinguished between basal bodies, one of which consisted of radiating fibers linking individual triplets of the longitudinal basal body to one triplet of the transverse. Some flagellar apparatus components were closely associated to a vesicle and to a mitochondrion. A ventral ridge extended from the (incomplete) longitudinal striated collar to the peduncular striated collar. The peduncle was supported by a single strand of microtubules, which were surrounded by numerous vesicles with electron-opaque contents.

Evidence from partial large-subunit (LSU) rDNA sequencing has been combined with ultrastructure, including details of the flagellar apparatus, in a number of phototrophic dinoflagellates, with the aim of trying to solve some of the most pressing taxonomic problems and to contribute to an improved understanding of the phylogeny within the group. Special attention has been paid to the unarmoured (naked) genera, many of which were described during the 1800s or early 1900s and whose taxonomy is artificial and misleading. This is particularly unsatisfactory because many of the species cause extensive plankton blooms, fish kills and other harmful events. Our studies have indicated that the path of the so-called apical groove (acrobase) is of particular importance for the taxonomy of the unarmoured genera of dinoflagellates. Features presently used to characterize many of the genera, such as the relative size of the epicone and hypocone, are misleading. Our data have resulted in the splitting of the large genus Gymnodinium into four genera. The fish-killing species are confined to two genera, Karenia G. Hansen & Moestrup gen. nov. and Karlodinium J. Larsen gen. nov. The paralytic shellfish poisoning-producing species Gymnodinium catenatum is retained within Gymnodinium, together with a number of harmless species. The fourth genus, Akashiwo G. Hansen & Moestrup gen. nov., presently comprises only the large nontoxic species previously known as Gymnodinium sanguineum. The genus Gyrodinium is redefined. The genus Amphidinium is artificial, but more data are needed before redescription of the genus can be made with any confidence. Within the armoured dinoflagellates, LSU and previously published small-subunit rDNA data show the Gonyaulacales to be a natural group. Peridiniella catenata, sometimes included in the Gonyaulacales based on gross morphology, falls outside this order both genetically and ultrastructurally. Based on the DNA data, the genus Peridinium appears to be artificial. Ultrastructure as well as gene sequences confirm that the genus Heterocapsa is unusual, since it includes both apparently unarmoured species (but with very thin plates) and armoured species.

Colopsinols D (1) and E (2), two new polyhydroxyl linear carbon chain compounds, have been isolated from the cultured marine dinoflagellate Amphidinium sp. The structures of 1 and 2 were elucidated on the basis of two-dimensional NMR and FAB-MS/MS data.

WE have seen groups of small (4–5 mm long) grey flies belonging to the species Lipochaeta slossonae Coquillett, 1896, standing, shaking and apparently feeding, or flying for short distances on stretches of wet sandy beach in La Jolla, California and San Felipe, Mexico. When undisturbed, they walked sideways or stood and shook their bodies, diagonally forward and downward, and backwards and upwards, at an estimated frequency of 5 s−1. We guessed that they were fluidising the wet sand under their feet and thereby loosening some of the interstitial microflora which could then be sucked up as a kind of soup. This was confirmed by laboratory examination of the guts of several specimens, which contained the remains of large numbers of cells of dinoflagellates and diatoms. (The species of dinoflagellates were unfortunately unidentifiable since there were no cell wall remains, but they probably belonged to the genus Amphidinium, which comprises some of the commonest unarmoured interstitial dinoflagellates on this beach. The diatom species, however, could be readily identified by their silica walls. There were at least 10 genera, all typical of the marine interstitial community, including various species of Navicula, Nitzschia, Pinnularia and Amphora.)

IN the course of an investigation into the nature of the soluble carbohydrate materials released by phytoplankton into their culture medium1, we found that media from cultures of Amphidinium carteri, a dinoflagellate, showed a distinctly blue reaction with N-ethyl carbazole, rather than the usual purple-red colour. The material causing the blue reaction could be removed by dialysis, which also removed the fishy odour characteristic of old cultures of this organism. The dialysate displayed the usual carbohydrate colour reaction.

A VARIED and interesting field of investigation awaits the microscopist who will make a detailed examination of the minute fauna, and flora of apparently barren sands on the seashore. To-day, on landing at the island of Oronsay at low tide, the otherwise pure white sand was seen to be coloured pink in one area, for an extent of several yards, green a little further up the beach, and golden-brown in small patches here and there. On examining samples with the microscope the brown colour was found to be due to living diatoms (not dinoflagellates in this case), naviculoid forms like Caloneis; the pink is formed of amorphous masses of fine granules in a jelly loosely adhering to the sand-grains, and may perhaps prove to be bacteria in a zoogloea state, while the green is caused by patches of a very simple alga (? a Coccophycid) made up of groups of rounded green ceils in a single layer on the sand-grains. I have kept samples of all the organisms and will submit them to a botanist for more precise identification. No Amphidinium patches were present so far as I could see. The variety of organisms present in the one little bay, the extraordinary abundance in each patch, and the brightness of the colour produced on the white sand were very striking, and seemed worthy of note.

Some physiological and pharmacological effects of cell extracts fromAmphidinium carteri cultures are described. Mice and fish were killed by injection of extracts from lyophilized cells concentrated by centrifugation.

The dinoflagellates are a group of microorganisms found commonly, but not exclusively, in samples of marine plankton. The number of their individuals and species varies considerably in both space and time, and relatively few studies have been made up to the present on the causes underlying such fluctuations. Observations on their nutritional requirements as deduced from laboratory culture, are believed to have an important bearing on these aspects. Unfortunately, little thorough work has been undertaken in this field. Sweeney (1951) provided a comprehensive resume of the laboratory culture of marine dinoflagellates as well as a valuable contribution on the factors stimulating the population growth of pure cultures of Gymnodinium splendens. A number of other species have also been grown in laboratory culture (Barker, 1935; Braarud, 1945; King, 1950) but to the author's knowledge the successful mass culture of Amphidinium has not been previously attained.

BIOLOGICAL readers of NATURE will perhaps recollect the record of the finding of the dinoflagellate, Amphidinium operculatum (previously unknown in Britain), on the beach at Port Erin a couple of years ago. Since then it has been present in great abundance at Port Erin on many occasions; Mr. R. D. Laurie has found it at Hoylake, near Liverpool, two of our young Liverpool zoologists (R. J. Daniel and J. E. Hamilton) now at the Belmullet Whaling Station, co. Mayo, inform me that they have noticed it on the shores of Blacksod Bay, and now I have to-day found it here in abundance, staining slightly in patches and streaks the beautiful white shell-sands of Iona.

Microalgae have received growing interest for their capacity to produce bioactive metabolites. This study aimed at characterising the antimicrobial potential of the marine dinoflagellate Amphidinium carterae strain LACW11, isolated from the west of Ireland. Amphidinolides have been identified as cytotoxic polyoxygenated polyketides produced by several Amphidinium species. Phylogenetic inference assigned our strain to Amphidinium carterae subclade III, along with isolates interspersed in different geographic regions. A two-stage extraction and fractionation process of the biomass was carried out. Extracts obtained after stage-1 were tested for bioactivity against bacterial ATCC strains of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa. The stage-2 solid phase extraction provided 16 fractions, which were tested against S. aureus and E. faecalis. Fractions I, J and K yielded minimum inhibitory concentrations between 16 μg/mL and 256 μg/mL for both Gram-positive. A targeted metabolomic approach using UHPLC-HRMS/MS analysis applied on fractions G to J evidenced the presence of amphidinol type compounds AM-A, AM-B, AM-22 and a new derivative dehydroAM-A, with characteristic masses of m/z 1361, 1463, 1667 and 1343, respectively. Combining the results of the biological assays with the targeted metabolomic approach, we could conclude that AM-A and the new derivative dehydroAM-A are responsible for the detected antimicrobial bioactivity.