bluuebunny/crossref_metadata_2025_split huggingface dataset:
ULTRASTRUCTURE OF GLOEODINIUM MONTANUM (DINOPHYCEAE)1
Authors: Kelley Ingrid , Pfester Lois A. 
Published: October 2004

ABSTRACTThe freshwater dinoflagellate Gloeodinium montanum Klebs (1912) was examined with transmission and scanning electron microscopy. Micrographs of ultrathin sections revealed a series of membrane layers rather than the usual dinoflagellate theca in vegetative cysts and in legates. Swarmers had distinct pellicles but appeared to be devoid of thecal plates and vesicles. The organization of cysts and swarmers appeared remarkably similar. All cell types had typical dinoflagellate nuclei with condensed chromosomes. Chloraplasts had girdle lamellae. One pyrenoid per cell was also present in chloroplasts of vegetative cysts. Starch grains and oil globules were distributed throughout the cytoplasm. Large accumulation bodies and polyvesicular vacuoles were found in aging cysts. Trichocysts and flagellar hairs were absent. Two types of intra‐cellular prokaryotic organisms were discovered.
INTRACELLULAR AND EXTRACELLULAR AMINO ACID POOLS OF THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) GROWN ON UNENRICHED SEAWATER IN HIGH‐CELL‐DENSITY DIALYSIS CULTURE1
Authors: Marsot Pierre , Cembella Allan D. , Colombo Juan Carlos 
Published: October 2004

ABSTRACTThe consumption of inorganic macronutrients (NO3−+ NO2−, NH4+, and PO4−3) and the composition of intra‐ and extracellular dissolved free amino acid pools (IDFAA and EDFAA, respectively) were determined in continuous‐reservoir batch dialysis cultures of the marine diatom Phaeodactylum tricornutum Bohlin maintained on unenriched natural seawater as a growth medium. Nutrient diffusion (Nd), which equals the nutrient uptake of the culture, increased with the cell density and the age of the culture. A concentration of 6.77 × 107 cells · mL−1 was obtained in stationary phase, which coincided with the NO3−+ NO2− diffusion limit (Ndmax) of the dialysis apparatus. The Ndmax for NH4+ occurred much earlier, at the end of exponential growth, whereas Ndmax for PO4−3 was not attained during the growth cycle of the culture, even in early stationary phase. A significant depletion (77%) of the IDFAA pool during exponential phase was followed by a reestablishment–to approximately 60% of the initial level–of internal pools during linear and stationary growth phases. This recovery occurred during the illuminated portion of the photoperiod (12:12 h LD) and involved principally the amino acids GLN, GLU, β‐GLU, and ASN. The recovery of GLN and ASN levels was particularly significant, because the intracellular concentrations of these amino acids were higher at the end of the growth cycle than before. The EDFAA pool was generally dominated by the amino acids SER and GLY+THR; however, during active growth, ORN and LYS often constituted an important fraction. The EDFAA concentration increased until linear growth phase was reached, during which a higher concentration of total free amino acids was attained in darkness than under illumination. The EDFAA component diminished afterward, and in stationary phase this fraction returned to concentrations equivalent to those observed at the beginning of the growth cycle. The variations in EDFAA concentrations were expressed by a pronounced decrease in the cellular excretion of amino acids with increasing cell density. These cellular responses of Phaeodactylum tricornutum in dense culture, specifically the regulation of amino acid excretion and intracellular pool size, may affect the N‐conversion coefficient (YN). Consequently, by prolonging the linear phase of growth and reducing the concentration of autoinhibitory metabolites by diffusion, a markedly enhanced final cell density can be achieved in cultures grown on natural unenriched seawater.
GLYCOLATE‐OXIDIZING ENZYMES IN ALGAE1
Authors: Suzuki Kensaku , Iwamoto Koji , Yokoyama Shinya , Ikawa Tomoyoshi 
Published: October 2004

ABSTRACTCharacteristics of glycolate‐oxidizing enzymes in crude extracts of algal species in the Chlorophyta, Chromophyta, Prymnesiophyta, Dinophyta, Cryptophyta, and Rhodophyta were compared by measuring glycolate‐dependent O2 consumption and dichlorophenolindophenol (DCPIP) reduction under anaerobic conditions and by checking cyanide sensitivity and the stereospecificity for d‐ and l‐lactate. Glycolate dehydrogenase similar to that found in the Chlorophyceae was found only in the Prasinophyceae, which is phylogenetically close to the Chlorophyceae, and in the Cryptophyta, the phylogenetically enigmatic algae. Glycolate oxidase was found in the Chromophyta except the Bacillariophyceae and in the rhodophyte Porphyridium purpureum (Bory) Drew & Ross. No detectable activity was found in the other rhodophytes, dinoflagellates, or prymnesiophytes. Glycolate dehydrogenase in the Bacillariophyceae was not cyanide‐sensitive and had a stereospecificity for l‐lactate. Catalase activity was observed at high levels in all algae possessing glycolate oxidase, but was not detected in the Bacillariophyceae, Prasinophyceae, and Cryptophyta, which have glycolate dehydrogenase activity. High levels of d‐lactate‐dependent DCPIP‐reducing activity were observed in the raphidophyte Heterosigma akashiwo (Hada) Hada, a major constituent of red tides on the coast of Japan, and in the Bacillariophyceae, but such activity was not catalyzed by the glycolate‐oxidizing enzymes nor NAD‐dependent lactate‐oxidizing enzymes.
MORPHOLOGICAL AND GENETIC VARIATION WITHIN THE DIATOM SKELETONEMA COSTATUM (BACILLARIOPHYTA): EVIDENCE FOR A NEW SPECIES, SKELETONEMA PSEUDOCOSTATUM1
Authors: Medlin Linda K. , Elwood Hille J. , Stickel Shawn , Sogin Mitchell L. 
Published: October 2004

ABSTRACTThe nuclear gene encoding the small subunit (16S‐like) ribosomal RNA molecule was sequenced from four isolates of the marine coastal planktonic diatom Skeletonema costatum (Grev.) Cleve. Each isolate originated from a geographically separate water mass. Sufficient morphological and genetic differences were found among the four isolates to support the description of a new species, Skeletonema pseudocostatum, which corresponds to the CCAP 1077/7 and CS‐76 isolates.
INGESTION AND RETENTION OFCHROOMONASSPP. (CRYPTOPHYCEAE) BYGYMNODINIUM ACIDOTUM(DINOPHYCEAE)1
Authors: Fields Stephen D. , Rhodes Russell G. 
Published: October 2004

ABSTRACTGymnodinium acidotumNygaard, a blue‐green dinoflagellate previously shown to contain cryptophycean chloroplasts and other organelles, was observed from water and soil samples and in culture. The dinoflagellate excysts from soil samples as a mononucleated colorless cell that is positively phototactic. Colorless cells in unialgal culture remain colorless and can only be maintained less than one week whereas pigmented cells cultured unialgally grow for 10 days but then decline rapidly. Colorless cells cultured withChroomonasspp. regain chloroplasts and have been maintained in mixed cultures for nine months. Fifty‐seven percent of the dinoflagellates from mixed cultures are bi‐nucleated, and three cells have been observed possibly ingesting cryptophytes. We suggest that cryptophycean chloroplasts are retained and possibly utilized byG. acidotumfor at least ten days and then digested.
PIGMENTS, FATTY ACIDS, AND STEROLS OF THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM1
Authors: Hallegraeff Gustaaf M. , Nichols Peter D. , Volkman John K. , Blackburn Susan I. , Everitt David A. 
Published: October 2004

ABSTRACTCultures and field samples of the toxic dinoflagellate Gymnodinium catenatum Graham from Tasmania, Australia, were analyzed for pigment, fatty acid, and sterol composition. Gymnodinium catenatum contained the characteristic pigments of photosynthetic dinoflagellates, including chlorophyll a, chlorophyll c2, and the carotenoids peridinin, dinoxanthin, diadinoxanthin, diatoxanthin, and β,β‐carotene. In midlogarithmic and early stationary phase cultures, the chlorophyll a content ranged 50–72 pg · cell−1, total lipids 956–2084 pg · cell−1, total fatty acids 426–804 pg · cell−1, and total sterols 8–20 pg · cell−1. The major fatty acids (in order of decreasing abundance) were 16:0, 22:6(n‐3), and 20:5(n‐3) (collectively 65–70% of the total fatty acids), followed by 16:1(n‐7), 18:2(n‐6), and 14:0. This distribution is characteristic of most dinoflagellates, except for the low abundance (<3%) of the fatty acid 18:5(n‐3), considered by some authors to be a marker for dinoflagellates. The three major sterols were 4α‐methyl‐5α‐cholest‐7‐en‐3β‐ol, 4α,23,24‐trimethyl‐5α‐cholest‐22E‐en‐3β‐ol (the dinoflagellate sterol, dinosterol), and 4α,23,24‐trimethyl‐5α‐cholest‐7‐en‐3β‐ol. These three sterols comprised about 75% of the total sterols in both logarithmic and early stationary phase cultures, and they were also found in high proportions (22–25%) in natural dinoflagellate bloom samples. 4‐Desmethyl sterols, which are common in most microalgae, were only present in trace amounts in G. catenatum. The chemotaxonomic affinities of G. catenatum and the potential for using specific signature lipids for monitoring toxic dinoflagellate blooms are discussed.
ENTRY OF A CHLORELLA‐VIRUS INTO ITS HOST CELL1
Authors: Reisser Werner , Kapaun Edwin 
Published: October 2004

ABSTRACTThe endosymbiotic Chlorella sp. (Chlorophyceae) of Paramecium bursaria (Ciliata) can be infected by a double‐stranded DNA‐containing virus (Chlorella‐virus) that has a phagelike entry mechanism. Electron micrographs show that soon after attachment of the virus to the algal cell wall, a hole is formed through which the viral DNA enters the alga. Biochemical studies on a European Chlorella‐virus system suggest that digestion of the algal cell wall is caused by glycolytic enzymes, one of which was identified as a β‐d‐glucosidase. Enzymes are bound to the virus capsid and are activated only after or by the attachment of the virus to its cognate alga or to preparations of the algal cell wall. Common features of viral cell wall‐digesting enzymes and algal autolysins are discussed.
HETEROMORPHIC LIFE HISTORIES IN ARCTIC COCCOLITHOPHORIDS (PRYMNESIOPHYCEAE)1
Authors: Thomsen Helge Abildhauge , Østergaard Jette Buch , Hansen Lise Evald 
Published: October 2004

ABSTRACTDuring three visits to Disko Bay, West Greenland, we found four different types of prymnesiophyte flagellates with heterococcoliths from species of the generaPapposphaeraTangen andPappomonasManton and Oates in characteristic and consistent combinations with holococcoliths from species of the generaTurrisphaeraManton, Sutherland, and Oates andTrigonaspisThomsen. We conclude that several taxa previously considered to be autonomous species are, in fact, part of life histories combining hetero‐ and holococcolithophorid forms in a manner somewhat similar to that known from studies of cultured strainsof Coccolithus pelagicus(Wallich) Schiller andCrystallolithus hyalinus(Gaarder) Markali. Similarly,CalciarcusManton, Sutherland and Oates andWigwammaManton, Sutherland and Oates also may be alternate phases of a coccolithophorid life history.
MORPHOLOGY OF CIGUATERA‐CAUSING PROROCENTRUM LIMA (PYRROPHYTA) FROM WIDELY DIFFERING SITES1
Authors: Faust Maria A. 
Published: October 2004

ABSTRACTClones of ciguatoxigenic Prorocentrum lima (Ehr.) Dodge 1975 were examined from different geographical areas (Pacific and Atlantic oceans) and compared with the earliest descriptions between 1881 and 1933 and light and electron micrographs of other researchers. Surface morphology of the widely distributed clones was remarkably similar, and morphological variability of ecotypes of this species is minimal. The number of valve pores (58–85 per valve) and marginal pores (55–72 per valve) is characteristic of the species. Marginal pores are located adjacent to the intercalary band in a regular pattern, are readily distinguishable by light microscopy, and are a good criterion for identifying P. lima. The periflagellar area of P. lima is a unique taxonomic feature; however, it can only be seen with the scanning electron microscope at high magnification. The anterior periflagellar area is a broad triangule, where the left valve margin is flat and the right valve has a V‐shaped depression. It accommodates a flagellar and an auxiliary pore and a flared, protuberant apical collar enclosed by eight small plates. The protuberant apical collar of P. lima has only been observed in one other Prorocentrum species, P. hoffmannianum, which has an areolated valve surface. In contrast, the valve surface of P. lima is smooth. Cells possess chloroplasts, a centrally located pyrenoid, a posterior nucleus, and two flagella. The shape and size of P. lima are variable and less useful for identifying specimens.
AGLAOTHAMNION WESTBROOKIAE SP. NOV. (RHODOPHYTA), A SPECIES PREVIOUSLY CONFUSED UNDER THE NAME CALLITHAMNION BYSSOIDES1
Authors: Rueness Jan , L'Hardy‐Halos Marie‐Therèse 
Published: October 2004

ABSTRACTWe propose the name Aglaothamnion westbrookiae sp. nov. for the alga referred to as Callithamnion byssoides Arnott ex Harvey in Hooker by Edwards and others from the eastern coast of North America. A. westbrookiae differs from the European A. byssoides (Arnott ex Harvey in Hooker) L'Hardy‐Halos et Rueness (= C. byssoides, type locality Cornwall, England) by having fronds branched pinnately, not spirally as in A. byssoides. The gonimolobes in A. westbrookiae are rounded, not conical and lobed as in A. byssoides. The spermatangia are in dense hemispherical clusters whereas in A. byssoides the equivalent structure is elongated. The two taxa are sexually incompatible. Aglaothamnion westbrookiae also differs in morphological features and is not interfertile with A. pseudobyssoides from France. We suggest that A. westbrookiae and A. feldmanniae Halos from Europe are similar in most features, including the involucral branches subtending carposporophytes. However, cross‐ability tests demonstrated that they are not interfertile, and differences in vegetative structure suggest that they should be treated as two different species.
UPTAKE OF NITRATE, AMMONIUM, AND UREA BY NITROGEN‐STARVED CULTURES OF MICROMONAS PUSILLA (PRASINOPHYCEAE): TRANSIENT RESPONSES1
Authors: Corhlan William P. , Harrison Paul J. 
Published: October 2004

ABSTRACTNitrogen uptake rates were measured as a function of time following saturating additions (15 μMg‐at N·−1) of 15N‐labelid ammonium, urea, and nitrate to N‐starved cultures of the picoflagellate Micromonas pusilla Butcher. Uptake rates were estimated from both the accumulation of 15N into the cells and the disappearance of nitrogen from the medium. Transient elevated (surge) uptake rates of NH4+ and urea were observed after enrichment. During the first 5 min the initial urea and NH4+ uptake rates were 2‐ and 4‐fold greater than the maximum growth rate (μMmax)observed prior to No3− depletion in the cultures. The elevated urea uptake rates declined quickly to a relatively constant value, whereas the initial rates of NH4+ uptake declined rapidly but were followed by a subsequent increase prior to remaining roughly constant. Nitrate was not taken up as readily by N‐starved M. pusilla as the reduced N forms. Although NO3+ uptake commenced immediately after enrichment (i.e. no lag period) the N‐Specific rate over the next 6 h averaged half the μMmax observed during NO3− replete conditions.
BLUE‐GREEN ALGAL MATS IN A SMALL STREAM1
Authors: Stuck Marsha S. , Ward Amelia K. 
Published: October 2004

ABSTRACTBedrock erosional features in a small stream (Little Schultz Creek, Bibb County, Alabama) created a variety of habitats for epilithic growth. One suck habitat was illustrated by the occurrence of small falls (<0.3 m) in the main channel of the stream and blue‐green algal mats associated with them. The cohesive, laminar algal mats were found at 15 such sites along a 250‐m reach of the stream. The primary mat matrix consisted of the blue‐green alga Oscillatoria submembranacea Ardissone and Strafforella. The uppermost portion of each mat consisted of a thin (<1 mm thick) green layer of biologically active filaments. The lower layers were thicker (up to 2 cm thick) and consisted of brown laminae of Oscillatoria filaments, and associated sediments. In addition, numerous diatoms mere associated with the mat surface. Some were loosely attached (e.g. Achnanthes); others (Cymbella tumida (Bréb.) V. H.) were stalked. These mats were present throughout the year and showed a bimodal annual distribution with maxima hi February and July. In February, total mat coverage was higher than in July. This winter maximum may have been related to a mode of growth dependent upon sedimentation from storm events and subsequent upward growth of the alga. Mat primary productivity on an areal basis (432 mg C · m−2· d−1 in March and 907 mg C · M−2· d−1 in April) was 2–12 times the maxima measured on epizoic and cobbles surfaces and other bedrock surfaces in the same stream. The limited areal coverage of the mats, when compared to other surfaces available for algal colonization, made them less important than other epilithic and epizoic surfaces in terms of total primary production in this stream reach. However, we propose that the combination of their unique structure and high primary productivity may make these algal mats sites of high algal and bacterial metabolic activity, which may include anaerobic processes in midchannel, where such activity would not be expected to occur.
EFFECT OF SPECTRAL QUALITY ON GROWTH AND PIGMENTATION OF PICOCYANOBACTERIA1
Authors: Hauschild Christopher A. , McMurter Heather J. G. , Pick Frances R. 
Published: October 2004

ABSTRACTThe influence of spectral quality on growth and pigmentation was compared among five strains of marine and freshwater picocyanobacteria grown under the same photon flux density (28 μE · m−2·s−1). Growth and phycoerythrin (PE) concentration per unit carbon increased when marine Synechococcus WH7803 was grown under green light as compared to red light, but no change in phycocyanin concentration occurred. Marine Synechococcus strain 48B66 also showed greater levels of PE when grown under green light than under red light, but no concomitant growth increase occurred. Both strains thus exhibited Group II chromatic adaptation. Additionally, strain 48B66 increased the relative level of phycourobilin compared to phycoerythrobilin when grown under red light. In contrast, both marine and freshwater Synechococcus strains containing no PE showed decreased growth under green light. Chlorophyll a concentrations were greatest or among the greatest in all strains grown under green light. These results suggest that light quality, through its effects on growth rate, may be an important factor controlling the distribution and abundance of the various pigment types of Synechococcus.
ACTIVE GLIDING MOTILITY IN AN ARAPHID MARINE DIATOM, ARDISSONEA (FORMERLY SYNEDRA) CRYSTALLINA1
Authors: Pickett‐Heaps Jeremy , Hill David R. A. , Blaze Kevin L. 
Published: October 2004

ABSTRACTActive gliding movement over long distances was observed and filmed in the marine pennate diatom Ardissonea (Synedra) crystallina (Agardh) Kütz. Typical speeds measured ca. 1–2 μm‐s−1. Motion wax often smooth and steady; however, discontinuous jerky motions and rolling movements were common. Motion, was associated with secretion of twin or, less commonly, single straight trails of mucilage from one end of the cell. In a few instances, reversal in direction was related to cessation of mucilage secretion at one end and commencement at the other. Temporary cessation of movement due to an obstruction was accompanied by a build‐up of mucilage at one end of the cell. Mucilage was apparently secreted at two specific sites at each end of the cell and was stained by alcian blue.Persistent trails were visible under scanning electron microscopy (SEM). SEM confirmed that cells had no raphes or labiate processes. The apparent site of secretion was a deep groove formed at the junction of the valve and valvocopula (first girdle band) at each end of the cell. Transmission electron microscopy confirmed the presence of mucilage vesicles in the cytoplasm, but these were not in any manner obviously related to secretion nor was any morphological structure associated with secretion. Cells often become epiphytic through secretion of a terminal stipe. Both stipe secretion and movement may involve the same structural differentiation of the frustule.These results demonstrate a previously unrecorded type of diatom motility. The mechanism, involves mucilage secretion and appears similar to that seen, for example, in some other algae such as the desmids (green algae).
GROWTH AND CELL CYCLE OF TWO CLOSELY RELATED RED TIDE‐FORMING DINOFLAGELLATES:GYMNODINIUM NAGASAKIENSEAND G. CF.NAGASAKIENSE1
Authors: Partensky Frédéric , Vaulot Daniel , Videau Christiane 
Published: October 2004

ABSTRACTSmall‐sized vegetative cells were found to co‐occur with normal‐sized cells in populations of the European bloom‐forming dinoflagellateGymnodiniumcf.nagasakienseTakayama et Adachi, currently known asGyrodinium aureolumHulburt, but not in populations of the closely related Japanese speciesGymnodiniumn agasakiense.We examined how cell size differentiation may influence growth and cell cycle progression under a 12:12‐h light: dark cycle in the European taxon, as compared to the Japanese one. Cell number and volume and chlorophyll red fluorescence in both species varied widely during the photocycle. These variations generally appeared to be related lo the division period, which occurred at night, as indicated by the variations of the fraction of binucleated cells (mitotic index) as well as the distribution of cellular DNA content. “Small” cells ofG.cf.nagasakiensedivided mainly during the first part of the dark period, although a second minor peak of dividing cells could occur shortly before light onset. In contrast, “large” cells displayed a sharp division peak that occurred 9 h after the beginning of the dark period. The lower degree of synchrony of “small” cells could be a consequence of their faster growth. Alternatively, these data may suggest that cell division is lightly controlled by an endogenous clock in “large” cells and much more loosely controlled in “small” cells. Cells of the Japanese species, which were morphologically similar to “large” cells of the European taxon, displayed an intermediate growth pattern between the two cell types ofG.cf.nagasakiense, with a division period that extended to most of the dark period.