bluuebunny/crossref_metadata_2025 huggingface dataset:
FURTHER STUDIES OF PRESUMEDLY PRIMITIVE GREEN ALGAE, INCLUDING THE DESCRIPTION OF PEDINOPHYCEAE CLASS. NOV. AND RESULTOR GEN. NOV.1
Authors: Moestrup Øjvind
Published: October 2004

The tiny jumping flagellate originally described as Pedinomonas mikron Throndsen was isolated into pure culture from Australian waters and its ultrastructure critically examined. Pedinomonas mikron differs in behavior and in features of the flagellar apparatus from P. minor, the type species from freshwater, and is referred to the new genus Resultor. The two genera are closely related and form the new class Pedinophyceae, which is characterized by features of the flagellar apparatus, mitosis, and cytokinesis. The flagella show the 11/5 orientation otherwise characteristic of Ulvophyceae and Pleurastrophyceae, but they are arranged end to end as in the Chlorophyceae. The flagellar root system is asymmetric and includes a rhizoplast that emerges from the base of one flagellum but subsequently associates with a microtubular root from the second basal body. Mitosis studied previously by Pickett‐Heaps and Ott in Pedinomonas is closed, unlike in other green algae, and the spindle is persistent. No phycoplast or phragmoplast is formed during cytokinesis. The eyespot of the Pedinophyceae is located at the opposite end of the cell from the flagella and adjacent to the pyrenoid, as in the most primitive members of the Prasinophyceae. Members of the Pedinophyceae lack prasinoxanthin and Mg 2,4D, characteristic of certain other primitive green algae.

The primitive green algae include the classes Prasinophyceae and Pedinophyceae. Micromonadophyceae Mattox et Stewart is considered a synonym of Prasinophyceae.

Two new orders are established, Pedinomonadales, containing all known members of the Pedinophyceae, and Scourfieldiales, with the single family Scourfieldiaceae fam. nov. and the single genus Scourfieldia.
SURVIVAL OF FUCOID EMBRYOS IN THE INTERTIDAL ZONE DEPENDS UPON DEVELOPMENTAL STAGE AND MICROHABITAT1
Authors: Brawley Susan H. , Johnson Ladd E.
Published: October 2004

Embryos of the fucoid alga Pelvetia fastigiata (J. Ag.) DeToni were outplanted into the intertidal zone to assess survival during the physical stress brought about by emersion during a single low tide. Survival varied among microhabitats. Under the adult Pelvetia canopy, survival of 6‐h‐, 24‐h‐, 48‐h‐, and 1‐wk‐old embryos was nearly 100%. Almost all embryos of all ages died in exposed habitats on bare rock or within habitats where the Pelvetia canopy was removed experimentally. However, within red algal turfs, where most juvenile Pelvetia occur, survival was unusually age specific: 24‐ to 48‐h‐old embryos survived poorly compared to younger (6 h old) or older embryos (1 wk old). Survival patterns reflected microhabitat temperatures during the experiments. The fate of young post‐settlement stages must be studied at these fine temporal and spatial scales to understand the organization of intertidal communities.
PLANKTONIC SARCODINES: MICROHABITAT FOR OCEANIC DINOFLAGELLATES1
Authors: Spero Howard J. , Angel Dror L.
Published: October 2004

Two morphologically distinct species of free‐swimming dinoflagellates belonging to the genusGyrodiniumutilize the spine and rhizopodial environments of planktonic foraminifera and colonial radiolaria as microhabitats. Up to 84% of the sarcodines examined in a given population were associated with these dinoflagellates at densities up to 20,000 cells per sarcodine in some radiolarian colonies. Both dinoflagellate species possess chloroplasts, indicating they are capable of autotrophy.14C‐labelling experiments with the radiolarian‐associated dinoflagellate demonstrate that it can take up inorganic carbon under both light and dark conditions. Ultrastructural evidence suggests the foraminiferal dinoflagellate may be capable of phagotrophy. Hence, these algae should be considered mixotrophs. An unusual cytoplasmic extension used for attachment and possibly feeding occurs in the foraminiferal‐associatedGyrodiniumand is documented with electron microscopy. Ultrastructural examination suggests this organelle may be hydrostatically controlled and may be an extension of the sac pusule.
A COMPARISON OF PERIPHYTIC ALGAL BIOMASS AND COMMUNITY STRUCTURE ON SCIRPUS VALIDUS AND ON A MORPHOLOGICALLY SIMILAR ARTIFICIAL SUBSTRATUM1
Authors: Goldsborough L. Gordon , Hickman Michael
Published: October 2004

Chemically inert, cylindrical rods positioned in the littoral of two eutrophic Alberta lakes supported higher periphytic algal biomass (measured as total chlorophyll a) than nearby morphologically similar culms of Scirpus validus Vahl. during most of the summer. Upon initiation of macrophyte senescence, biomass on the two substrata became more similar. Experiments were conducted to investigate the basis for these observations. Whole extracts of intact vegetative Scirpus culms had no effect on periphyton photosynthesis, suggesting that the natural substrata do not produce water‐soluble allelochemicals. Various modifications of the rod surfaces (roughening, wax coating, wax color) were used to test whether surficial properties of Scirpus culms influenced periphyton accumulation. Roughened rods supported levels of biomass similar to those of smooth rods, and both substrata developed structurally complex periphyton communities. Rods covered with paraffin wax had periphyton communities that were lower in biomass and structurally more simple than those on un‐coated rods or on Scirpus culms. Coloring of the wax coating had no consistent effect on periphyton accumulation. We hypothesize that the hydrophobic cuticle on actively growing Scirpus culms retards the development of precursors for attachment by periphytic algae. Upon senescence of the culm and loss of epidermal integrity, colonization of culm surfaces by periphytic algae may occur in a manner similar to that on artificial substrata.
CELL DIVISION IN GLOEOTILOPSIS PLANCTONICA, A NEWLY IDENTIFIED ULVOPHYCEAN ALGA (CHLOROPHYTA) STUDIED BY FREEZE FIXATION AND FREEZE SUBSTITUTION1
Authors: Sluiman Hans J.
Published: October 2004

Gloeotilopsis planctonica Iyengar & Philipose, a soil isolate, was cultured for the first time since its description in 1956. Cell division was investigated ultrastructurally by using rapid freeze fixation and freeze substitution. Vegetative interphase cells contain a persisting basal apparatus (centrioles) in which the absolute configuration of the basal body pair is identical to that in ulvophycean flagellated cells. Basal apparatus replication and segregation occurs shortly before prophase. Also before mitosis, a shallow plasma membrane indentation is formed, subtended by 2–3 cortical microtubules, in the forthcoming division plane. Daughter basal body pairs are located lateral to the mitotic spindle poles. A Golgi stack occupies each polar position of the mitotic spindle. During mitosis, which is structurally identical to that described previously for members of the Ulotrichales sensu Sluiman (Ulvophyceae), an extensive network of tubular membranes (trans Golgi reticulum, TGR) develops from each polar Golgi stack to the incipient cleavage furrow. A microtubular system, possibly organized by the basal apparatus, is associated with both the TGR and the cytokinetic septum. The TGR appears to be involved in the further development of the furrow after mitosis is completed. I conclude on the basis of this ultrastructural study that the genus Gloeotilopsis, which includes G. planctonica Iyengar & Philipose (type species) and G. sterilis Deason, should be classified in the Ulotrichales sensu Sluiman, class Ulvophyceae.
ISOZYME ANALYSIS OF MATING POPULATIONS OFGONIUM PECTORALE(CHLOROPHYTA)1
Authors: Sako Yoshihiko , Shrestha Keshab , Uchida Aritsune , Ishida Yuzaburo , Saito Shoichi
Published: October 2004

Intraspecific variation among 36 strains of the freshwater algaGonium pectoraleMüller (Chlorophyceae) isolated from three geographically different locations in Tibet, Nepal, and Japan was investigated by isozyme analysis. Variation in isozyme patterns of eight enzyme systems (malate dehydrogenase, glutamate dehydrogenase, tetrazolium oxidase, lactate dehydrogenase, octanol dehydrogenase, xanthine dehydrogenase, phosphoglucomutase, and malic enzyme) of axenic and clonal cultures was revealed by polyacrylamide gel electrophoresis. Unweighted average linkage clustering, based on Jaccard's similarity coefficient, illustrated the high similarity between most strains from Nepal and all strains from the Ryukyu Islands (Japan). However, there was relatively low similarity between strains from Tibet and those from Nepal and Japan. Strains from the Ryukyu Islands (Japan) grouped into two clusters, and most Nepalese strains formed a single cluster, but Tibetan strains were heterogenous.
CELL SURVIVAL CHARACTERISTICS AND MOLECULAR RESPONSES OF ANTARCTIC PHYTOPLANKTON TO ULTRAVIOLET‐B RADIATION1
Authors: Karentz Deneb , Cleaver James E. , Mitchell David L.
Published: October 2004

Twelve species of Antarctic diatoms were studied to assess UV sensitivity in relation to cellular and molecular aspects of DNA damage and repair. Responses of cell survival, induction of DNA damage, and DNA repair capacity were determined. There was a wide range of interspecific UV‐sensitivity among diatoms. D37 values (average fluence to kill one cell) ranged from 681 J · m−2 (most sensitive) to 25,338 J · m−2 (most resistant). Molecular analysis (by radioimmunoassay) of UV‐induced DNA damage [induction of cys‐syn cyclobutane dimers and pyrimidine (6‐4) pyrimidone photoproducts] also revealed considerable variability among species [0.98–84 lesions · (108 daltons DNA)−1 induced by exposure to 2500 J · m−2]. Repair of DNA damage ranged from 0.18 to 2.72 lesions removed · (108 daltons DNA)−1 in 6 h; removal represented 0.72–73.5% of initial damage. Comparison of cellular responses associated with photoenhanced repair and nucleotide excision (“dark”) repair indicated that light‐mediated correction of UV damage was an important factor in cell survival. There was a relationship between the number of photoproducts induced and cell survival, but not between repair efficiency and survival. The data also indicate a general dependence of photoproduct induction and D37 values on cell size and shape (expressed as the surface area: volume ratio which ranged from 0.07 to 0.66 between species) and suggest that these factors are indicators of UV sensitivity. Smaller cells with greater surface area: volume ratios sustained more damage per unit of DNA, had lower D37 values, and were more sensitive to UV exposure. The wide species variations observed in molecular and cellular responses to UV exposure emphasize the ecological implications of changes in natural UV regimes. These changes can act as determinants of cell size and taxonomic structure within phytoplankton communities and have as yet unknown effects on trophic interactions within the Antarctic ecosystem.
CIRCANNUAL GROWTH RHYTHM AND PHOTOPERIODIC SORUS INDUCTION IN THE KELPLAMINARIA SETCHELLII(PHAEOPHYTA)1
Authors: tom Dieck Inka
Published: October 2004

Growth and reproduction of laboratory‐grown sporophytes ofLaminaria setchelliiSilva were investigated in a tank system with controlled conditions of daylength, temperature, and nutrients (N and P). A circannual growth rhythm of the frond was detected under constant laboratory conditions. In continuous long‐day and night‐break conditions the period τ of the free‐running rhythm varied between 11.3 and 17.3 months; in short‐day conditions the frond grew indefinitely. The growth rhythm of individual plants could be synchronized by a simulated annual cycle of day‐length with a period of T = 12 months. The four seasons of the year were simultaneously simulated by phase shifting the annual cycle of daylength by 3, 6, or 9 months in three out of four tanks. The annual growth cycle followed these phase shifts, and initiation of the new blade always started just after the winter daylength minimum. The formation of sori was induced by a genuine photoperiodic short‐day reaction in 1‐ to 2‐year‐old plants. Sori became, visible 9–14 weeks after transfer of individual plants from long‐day to short‐day conditions, whereas plants cultured in continuous long‐day or night‐break conditions remained sterile. Sporophytes with or without blades were able to continue growth or produce new blades in continuous darkness.
RATES OF PHOTOADAPTATION IN SEA ICE DIATOMS FROM MCMURDO SOUND, ANTARCTICA1
Authors: Lizotte Michael P. , Sullivan Cornelius W.
Published: October 2004

Sea ice microalgae are released from their relatively stable light environment to the water column seasonally, and any subsequent growth in a vertically mixed water column may depend, in part, on their photoadaptation rates. In this study we followed the time course of photoadaptation in natural sea ice algal communities from bottom ice and surface ice by measuring their photophysiological response to an artificial shift in the ambient irradiance field. Microalgae from under‐ice habitats, were incubated under full sunlight (LL‐HL) and microalgae from surface ice habitats were incubated under artificial light to mimic under‐ice irradiance (HL‐LL). During 3‐ to 4‐day time course studies, opposite shifts in chlorophyll: carbon, α, PBm, and Ik were observed, depending on the direction of the irradiance change. First‐order rate constants (k) ranged from 0.0067 to 0.29 h−1 for photosynthetic parameters, although PBm did not always show a clear change over time. Rates of photoadaptation for ice algae are comparable to k values reported for temperate phytoplankton, suggesting that sea ice algae may be equally capable of adapting to the light conditions experienced in a vertically mixed water column. This study presents the first evidence that sea ice microalgae are physiologically capable of adapting to a planktonic life and thus could serve as a seed population for polar marine phytoplankton blooms.
RESPONSE OF PERIPHYTON COMMUNITIES TO CLAY AND PHOSPHATE LOADING IN A SHALLOW RESERVOIR1
Authors: Burkholder JoAnn M. , Cuker Benjamin E.
Published: October 2004

Enclosures in a small piedmont reservoir in the southeastern United States were used to determine the effects of loading by phosphate and two clay sediments on periphyton community structure and production during the summer growing season. The experimental design included replicated controls and the following treatments added at 2‐to 3‐day intervals: phosphate (PHOS), kaolinite (KAOL), montmorillonite (MONT), kaolinite with phosphate (K+P), and montmorillonite with phosphate (M+P). Periphyton were sampled from polyethylene strips of the same material as the enclosure walls, suspended at depths of 0.5 m and 2.0 m to assess treatment effects on shallow (epilimnetic) vs. deep (hypolimnetic) communities. Colonization after 40 days was sparse, dominated in biovolume by blue‐green algae in all but the epilimnion of controls, in which small gelatinous green algae and chrysophyte flagellates were abundant. The biovolume of shallow periphyton after 79 days was lowest in KAOL and MONT, intermediate in controls and PHOS, and greatest in clay + P. Hence, P enrichment alleviated the deleterious effects of clay on periphyton production, and clay + P appeared to act synergistically in stimulating benthic algal growth. Periphyton biovolume was comparable among shallow and deep controls, PHOS, and treatments with the rapidly settling kaolinite. Lowest biovolume occurred at depth in treatments with montmorillonite under extreme light attenuation imposed by the suspended, finely particulate clay. The relative contribution of blue‐green algae to total periphyton production was highest in clay + P treatments and lowest in controls. Heterotrophic dinoflagellates increased in the shallow periphyton under clay loading, and in the deep communities under PHOS and M + P. Periphyton contributed only 20–32% of total mesocosm productivity in controls, PHOS, and KAOL, increasing to about 40% in MONT, and to 72–91% of the total in M + P and K + P. The data indicate that benthic microalgae can represent a major proportion of the primary production in shallow reservoirs under high phosphate and sediment loading.
STIMULATION OF NITRATE NET UPTAKE AND REDUCTION BY RED AND BLUE LIGHT AND REVERSION BY FAR‐RED LIGHT IN THE GREEN ALGA ULVA RIGIDA1
Authors: López‐Figueroa Félix , Rüdiger Wolfhart
Published: October 2004

The steady‐state levels of nitrate, nitrite, and ammonium were estimated in the green alga Ulva rigida C. Agardh in darkness after addition of 0.5 mM KNO3 and irradiation with red (R) and blue (B) light pulses of different duration (5 and 30 min). The net uptake of nitrate was very rapid. Seventy‐five percent of the nitrate added was consumed after 60 min in darkness. Although uptake was stable after R or B, efflux of nitrate occurred within 3 h in the dark control and when R or B were followed by far‐red (FR) irradiation. The internal nitrate concentration after 3 h in darkness was similar after R and B light pulses; however, the intracellular ammonium was higher after R than after B. The intracellular nitrate and ammonium decreased when FR tight pulses were applied immediately after R or B. Thus, the involvement of phytochrome in the transport of nitrate and ammonium is proposed.

Nitrate reductase activity, measured by the in situ method, was increased by both R and B light pulses. The effect was partially reversed by FR light. Nitrate reductase activity was higher after 5 min of R light than after 5 min of B. However, after 30‐min light pulses, the relative increase in activity was reversed for R and B. We propose that phytochrome and a blue‐light photoreceptor are involved in regulation of nitrogen metabolism. Nitrate uptake and reduction correlates with previously detected light‐regulated accumulation of protein in Ulva rigida under the same experimental conditions.
CHARACTERIZATION AND BIOLOGICAL IMPLICATIONS OF SCYTONEMIN, A CYANOBACTERIAL SHEATH PIGMENT1
Authors: Garcia‐Pichel Ferran , Castenholz Richard W.
Published: October 2004

Scytonemin, the yellow‐brown pigment of cyanobacterial (blue‐green algal) extracellular sheaths, was found in species thriving in habitats exposed to intense solar radiation. Scytonemin occurred predominantly in sheaths of the outermost parts or top layers of cyanobacterial mats, crusts, or colonies. Scytonemin appears to be a single compound identified in more than 30 species of cyanobacteria from cultures and natural populations. It is lipid soluble and has a prominent absorption maximum in the near‐ultraviolet region of the spectrum (384 nm in acetone; ca. 370 nm in vivo) with a long tail extending to the infrared region. Microspectrophotometric measurements of the transmittance of pigmented sheaths and the quenching of ultraviolet excitation of phycocyanin fluorescence demonstrate that the pigment was effective in shielding the cells from incoming near‐ultraviolet‐blue radiation, but not from green or red light. High light intensity (between 99 and 250 μmol photon · m−2· S−1, depending on species) promoted the synthesis of scytonemin in cultures of cyanobacteria. In cultures, high light intensity caused reduction in the specific content of Chl a and phycobilins, increase in the ratio of total carotenoids to Chl a, and scytonemin increase. UV‐A (320–400 nm) radiation was very effective in eliciting scytonemin synthesis. Scytonemin production was physiological and not due to a mere photochemical conversion. These results strongly suggest that scytonemin production constitutes an adaptive strategy of photoprotection against short‐wavelength solar irradiance.
ULTRASTRUCTURE OF GLOEODINIUM MONTANUM (DINOPHYCEAE)1
Authors: Kelley Ingrid , Pfester Lois A.
Published: October 2004

The 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

The 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

Characteristics 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

The 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

Gymnodinium 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

Cultures 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

The 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

During 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

Clones 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

We 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

Nitrogen 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

Bedrock 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

The 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

Active 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

Small‐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.
ULTRASTRUCTURE OF VEGETATIVE AND DIVIDING CELLS OF THE UNICELLULAR RED ALGAERHODELLA VIOLACEAANDRHODELLA MACULATA1
Authors: Patrone Laura M. , Broadwater Sharon T. , Scott Joseph L.
Published: October 2004

Rhodella violacea(Kornmann) Wehrmeyer andRhodella maculataEvans were investigated for ultrastructural details of vegetative and dividing cells.Rhodella violaceahas a nuclear projection into the pyrenoid similar to that found inR. maculata, although the nuclear projection inR. maculatatraverses a starch‐lined area before contacting the pyrenoid. Unlike most, red algae, the twoRhodellaspecies lack a peripheral encircling thylakoid in the chloroplast and have dictyosomes associated solely with endoplasmic reticulum (ER) instead of with both mitochondria and ER. Both species also have a well‐developed peripheral system of ER connected to the plasmalemma by tubules, a situation found only in red algal unicells, Cell division was studied primarily inR. violacea;a less thorough examinationof R. maculatashowed no essential differences. Both have small, double‐ringed, nucleus‐associated organ files (NAOs) surrounded by moderately electron‐dense material, metaphase–anaphase polar gaps in the nuclear envelope, absence of perinuclear ER. and short interzonal spindles. This pattern of mitosis is similar in most respects to that reported in the unicellFlintiella.Following mitosis, microtubules extend from the region of each NAO to its associated nucleus and to the undivided pyrenoid. The NAOs appear to apply tension to the nuclei and the pyrenoid and may be the mechanism for ensuring equal partitioning of both organdies. Two different forms of pyrenoid‐nucleus association occur during mitosis. Nuclear projections into the pyrenoid, prevalent during interphase and early stages of mitosis, recede at metaphase. Then, the pyrenoid extends protrusions into the nuclear polar areas, forming a cup that partially surrounds the nucleus. Cell division and vegetative characters confirm the close taxonomic affinity of these two species ofRhodellaand support their separation from the genusPorphyridium.
AMPLIFICATION OF THE POLYMORPHIC 5.8S rRNA GENE FROM SELECTED AUSTRALIAN GIGARTINALEAN SPECIES (RHODOPHYTA) BY POLYMERASE CHAIN REACTION1
Authors: Steane Dorothy A. , McClure Bruce A. , Clarke Adrienne E. , Kraft Gerald T.
Published: October 2004

We have initiated comparative studies of ribosomal RNA (rRNA) gene structure to explore its potential to provide taxonomically useful data within the large red algal order Gigartinales. In southern Australia, this group is extremely diverse and includes large numbers of endemic taxa, many of potential economic importance. The 5.8S rRNA gene occurs in the middle region of the ribosomal DNA (rDNA) cistron and is flanked by two internal transcribed spacers (ITSs). These spacers contain regions of DNA, which are highly consented at the generic level and above, interspersed with highly divergent sequences. The 5.8S and associated ITS s of 11 species of Gigartinales (including five species of the largest Australian endemic marine algal genus, Mychodea), plus five taxa belonging to other orders, were amplified by the polymerase chain reaction. The size of the 5.8S rDNA and its flanking ITSs varied not only within and between genera, but also at the species level. However, this rDNA sequence appears to be relatively constant within populations find may be useful as a populational marker.
REPRODUCTIVE PLASTICITY IN THE KELPALARIA NANA(PHAEOPHYCEAE)1
Authors: Pfister Catherine A.
Published: October 2004

Unlike terrestrial plants, reproductive control in algae has not been attributed to biotic factors or internal chemical signals. However, experimental removal of reproductive structures (sporophylls) from the kelpAlaria nanaShrader resulted in the development of functional reproducing structures on the vegetative frond in 45% (10/22) of the experimental plants but not on the control plants where sporophylls were left intact (n = 35). In naturally occurringAlaria nana, this compensatory reproductive response occurred at a low incidence and was restricted primarily to larger individuals in the population. Thus, compensation and developmental plasticity, mediated In plant size, may play an important role in how algae respond to reproductive tissue loss.
The transactivating function of peroxisome proliferator‐activated receptor γ is negatively regulated by SUMO conjugation in the amino‐terminal domain
Authors: Yamashita Daisuke , Yamaguchi Tomohiro , Shimizu Makoto , Nakata Nagisa , Hirose Fumiko , Osumi Takashi
Published: October 2004

Peroxisome proliferator‐activated receptor (PPAR)‐γ2, a member of the nuclear hormone receptor superfamily, plays a key role in adipocyte differentiation. Its amino‐terminal region carries a ligand‐independent gene‐activating function, AF‐1, and is composed of activation as well as repression domains. We have found PPARγ2 and its isoform, PPARγ1, to be modified by small ubiquitin‐related modifier (SUMO)‐1 in vivo, at a lysine residue in the repression domain. In reporter assays, a sumoylation‐defective K107R mutant of PPARγ2 exhibited much stronger transactivation than the wild‐type, comparable with that of a mutant deleted for the repression domain. A close inverse correlation was observed between the levels of sumoylation and transactivation by PPARγ2, in analyses employing PPARγ2 forms with mutations in the sumoylation motif and a dominant‐negative mutant of the SUMO conjugating enzyme, Ubc9. Studies with phosphorylation‐defective mutants suggested that phosphorylation at S112 of PPARγ2 promotes K107 sumoylation, and this latter exerts the more potent repressive effects. The K107R mutant PPARγ2, when infected into NIH3T3 cells with a viral vector, promoted differentiation into adipocytes more efficiently than the wild‐type. These observations provide evidence that sumoylation is involved in negative regulation of the transactivating function of PPARγ2.