bluuebunny/crossref_metadata_2025_split huggingface dataset:
OCCURRENCE AND ABUNDANCE OF GREEN‐FLUORESCING DINOFLAGELLATES IN SURFACE WATERS OF THE NORTHWEST ATLANTIC AND NORTHEAST PACIFIC OCEANS1
Authors: Shapiro Lynda P. , Haugen Elin M. , Carpenter Edward J. 
Published: October 2004

ABSTRACTWe have cultured green fluorescing heterotrophic dinoflagellates whose continuous green fluorescence is due to an unidentified compound, probably a flavin, that excites with blue (∼460 nm) light and emits green (∼535 nm) light. No evidence of bioluminescence was found, but we note that compounds with similar fluorescence characteristics have been associated with bioluminescence in other taxa. These cells, all naked gymnodinoids, are widespread and abundant in the Northwest Atlantic and Northeast Pacific Oceans (103–105 L−1). They comprise 4–100% of the total heterotrophic dinoflagellate component which, in turn, is usually equivalent magnitude to the phototrophic naked dinoflagellate component of the phytoplankton community.
STRIP‐LIKE COVERING REVEALED ON “WALL‐LESS”ASTEROMONAS (CHLOROPHYCEAE)1
Authors: Chappell Dorothy F. , Hoops Harold J. , Floyd Gary L. 
Published: October 2004

ABSTRACT Asteromonas Artari previously described as a wall‐less biflagellated unicell exhibits a strip‐like cell covering on some cells. Both tannic acid fixation and freeze‐etch reveal the covering of electron opaque strips outside the plasmalemma. Cross striations are apparent in the surface strips. Golgi vesicles contain material presumed to be precursor components of the covering strips. The crystalline pattern of the freeze‐etched material is similar to that reported for other, walled volvocalean algae.
GENITIC VARIABILITY IN TOXIN POTENCIES AMONG SEVENTEEN CLONES OF GAMBIERDISCUS TOXICUS (DINOPHYCEAE)1
Authors: Bomber Jeffrey W. , Tindall Donald R. , Miller Donald M. 
Published: October 2004

ABSTRACTSeventeen clones of the ciguatera‐causing dinoflagellate Gambierdiscus toxicus Adachi and Fukuyo were acclimated to the same environments over several months. Significant variance components were detected between non‐acclimated and acclimated cultures for cell potencies, yields and reproduction rates. The resultant variance in acclimated potencies among clones was statistically significant (P < 0.0001), indicating that potency can be used for genetic comparisons. However, cell potency differences for a clone of G. toxicus in the acclimated vs. non‐acclimated phases can exceed genetic differences between clones. This stresses the need for a rigorous acclimation process. Caribbean isolates of G. toxicus were inherently more toxic than isolates from other areas. One Caribbean clone yielded 55 × 10−4 mu (mouse units)·cell−1 whereas clones Bermuda, the Bahamas, and Florida ranged from only 1.8 × 10−4 mu·cell−1 to a maximum of 19.8 × 10−4 mu·cell−1. Toxicity decreased with increasing latitude (r =–0.819, P < 0.01), indicating that environmental differences probably influenced the potencies. A comparison of acclimated reproduction rates at four light intensities also indicated that genetic differences among clones existed. The resulting reproduction rate/light slopes overlapped, indicating that the clones may be adapted to specific light regimes.
AN EXPANDED SURVEY OF THE ULTRASTRUCTURE OF RED ALGAL PIT PLUGS1
Authors: Pueschel Curt M. 
Published: October 2004

ABSTRACTThe fine structure of pit plugs in 90 species of red algae was examined, bringing the total number of species in the continuing survey to 153. The organization of plug caps was confirmed to be a stable, predictable trait within thalli, between generations in heteromorphic life histories, and within the presently recognized orders, with one exception—the Acrochaetiales. Two forms of the outer cap were found in this group, a thin plate, as in the Nemaliales and Palmariales, and a dome, as in Batrachospermales and Corallinales. Variation of pit plug structure indicates that the Acrochaetiales are a heterogeneous assemblage and that pit plugs will be useful in reappraising their systematics. The systematic affinities of several species of uncertain affinities are clarified.Schmitziella endophloeaBornet et Batters is excluded from both orders, Corallinales and Acrochaetiales, with which it previously was allied. Although other ordinal attributions are not precluded by pit plug structure alone, pit plug structure is consistent with placement ofApophlaea sinclairiiHarvey andHildenbrandia rivularis(Liebman) J. Agardh in the Hildenbrandiales,Plagiospora gracilisKuckuck,Schmitziella endophloea,andWurdemannia miniata(Duby) J. Feldmann et Hamel in the Gigartinales, andPseudorhododiscus nipponicusMasuda in the Palmariales.
EFFECTS OF NUTRIENT ENRICHMENT ON NATURAL POPULATIONS OF THE BROWN TIDE PHYTOPLANKTON AUREOCOCCUS ANOPHAGEFFERENS (CHRYSOPHYCEAE)1
Authors: Keller Aimee A. , Rice Robin L. 
Published: October 2004

ABSTRACTThe brown tide picoalga Aureococcus anophagefferens Hargraves et Sieburth was present in approximately equal numbers in 12 large scale (13,000 L) mesocosms at the start of a nutrient addition experiment in June 1985. Increases in abundance in untreated systems mimicked the pattern of bloom development in Narragansett Bay, Rhode Island, the seawater source for the experiment. Aureococcus increased to maximal values of 2.6 × 109 cells. L−1 and persisted at high numbers (108 cells·L−1) for 7–8 weeks. In nutrient addition tanks, the picoalgae bloomed briefly (1–3 weeks) but rapidly declined to the usual level (∼107 cells·L−1) for eukaryotic algae in Narragansett Bay. The decline in picoalgae abundance was followed by an increase in total diatoms in all nutrient treated tanks. Mean picoalgae abundance in the mesocosms and the bay was significantly (P < 0.05) and inversely correlated (r =–0.93) with mean concentration of dissolved inorganic nitrogen. The persistence of the brown tide species in control mesocosms and Narragansett Bay appears related to its ability to grow at very low concentrations of dissolved inorganic nitrogen, levels previously shown to limit diatom growth.
LIPOPHILIC PIGMENTS FROM CYANOBACTERIAL (BLUE‐GREEN ALGAL) AND DIATOM MATS IN HAMELIN POOL, SHARK BAY, WESTERN AUSTRALIA1
Authors: Palmisano Anna C. , Summons Roger E. , Cronin Sonja E. , Des Marais David J. 
Published: October 2004

ABSTRACTLipophilic pigments were examined in microbial mat communities dominated by cyanobacteria in the intertidal zone and by diatoms in the subtidal and sublittoral zones of Hamelin Pool, Shark Bay, Western Australia. These microbial mats have evolutionary significance because of their similarity to lithified stromatolites from the Proterozoic and Early Paleozoic eras. Fucoxanthin, diatoxanthin, diadinoxanthin, β‐carotene, and chlorophylls a and c characterized the diatom mats, whereas cyanobacterial mats contained myxoxanthophyll zeaxanthin, echinenone, β‐carotene, chlorophyll a and, in some cases, sheath pigment. The presence of bacteriochlorophyll a with in the mats suggest a close association of photosynthetic bacteria with diatoms and cyanobacteria. The high carotenoids: chlorophyll a ratios (0.84–2.44 wt/wt) in the diatom mats suggest that carotenoids served a photoprotective function in this high light environment. By contrast, cyanobacterial sheath pigment may have largely supplanted the photoprotective role of carotenoids in the intertidal mats.
ELECTRON MICROSCOPY OF A CONTRACTILE‐VACUOLE MUTANT OF CHLAMYDOMONAS MOEWUSII (CHLOROPHYTA) DEFECTIVE IN THE LATE STAGES OF DIASTOLE1
Authors: Denning Gerene M. , Fulton Alice B. 
Published: October 2004

ABSTRACTElectron microscopy of a “vacuole‐less” mutant of Chlamydomonas moewusii Gerloff revealed the presence of small anterior vacuoles. These vacuoles behaved like contractile vacuoles in wild‐type cells, but they were apparently unable to complete diastole and discharge their contents. When wild‐type and mutant cells were incubated in hypertonic medium, small coated vacuoles persisted in the region where contractile vacuoles form. When these cells were transferred to hypotonic medium, the vacuoles appeared to fill and fuse to form larger vacuoles Shortly after the appearance of full expanded contractile vacuoles, collapsed vacuoles were observed in wild‐type cells suggesting the completion of diastole and the onset of systole. In mutant cells, the initial steps of filling and fusion to form larger vacuoles apparent interactions of vacuoles with the plasma membrane were not observed. New contractile vacuoles accumulated around the nucleus. When fusion of the contractile vacuole with the plasma membrane was blocked by EGTA, a similar accumulation of large vacuoles occurred. Our observations suggest that the contractile‐vacuole mutant of C. Moewusii produces vacuoles which can accumulate excess water as part of the mechanism of osmoregulation but which cannot complete diastole.
SALINITY AND NUTRIENT LIMITATIONS ON GROWTH OF BENTHIC ALGAE FROM TWO ALKALINE SALT LAKES OF THE WESTERN GREAT BASIN (USA)1
Authors: Herbst David B. , Bradley Timothy J. 
Published: October 2004

ABSTRACTEnrichment cultures of littoral benthic algae from Mono Lake, California, and Abert Lake, Oregon, were grown under conditions of varied salinity and nutrient content. Field‐collected inocula were composed mainly of diatoms and filamentous blue‐green and green algae. The yield of long‐term cultures (30 days) showed tolerance over a broad salinity range (50–150 g·L−1) for Mono Lake‐derived algae. Algae from Abert Lake had a lower range of tolerance (25–100 g·L−1) Organic content and pigment concentrations of algae from both lakes were also reduced above the tolerated salinity level. Within the range of salinity tolerance for Mono Lake algae, initial growth rates and organic content were reduced by increased salinity. The effects of macro‐ and micronutrient enrichment on algal growth in Mono Lake water were also tested. Only nitrogen enrichment (either as ammonium or nitrate) stimulated algal growth. Although the benthic algae cultured here had wide optima for salinity tolerance, the rates of growth and storage were limited by increased salinity within the optimum range. Although the lakes compared had similar species composition, the range and limits of tolerance of the algae were related to salinity of the lake of origin.
REGULATION OF FATTY ACID COMPOSITION BY IRRADIANCE LEVEL IN THE EUSTIGMATOPHYTENANNOCHLOROPSISSP.1
Authors: Sukenik Assaf , Carmeli Yael , Berner Tamar 
Published: October 2004

ABSTRACTChemical composition and quantitative cytological measurements were determined for the eustigmatophyteNannochloropsissp. Cultures were grown in turbidostats at three irradiance levels: growth‐limiting light, growth‐saturating light and photoinhibiting light. Cellular chlorophyll a content decreased as irradiance level increased, concomitant with a disproportionate reduction in carotenoid content.Nannochloropsissp. grown in saturating light was characterized by a high content of lipid, fatty acids and carbohydrate compared with cells grown in light‐limiting conditions. The increase in cellular lipid content coincided with a reduction in the percentage of eicosapentaenoic acid (C20:5) and arachidonic acid (C20:4), fatty acids that are mainly associated with galactolipids, and with an increase in the relative abundance of palmitic acid (C16:0) and palmitoleic acid (C16:1). At growth limiting light conditions,Nannochloropsissp. preferentially synthesized galactolipids; however, as growth became light saturated, relatively more neutral lipids, mainly triacylglycerols, were synthesized. Changes in lipid content and composition were qualitatively related to changes in cell morphology. Cells grown under low light conditions were characterized by a large relative volume of chloroplast, high surface density of thylakoid membranes and low relative volume of lipid storage bodies. The physiological implications of the changes in cellular lipid composition and ultrastructure are discussed in relation to light/shade adaptation.
FUNCTIONAL‐MORPHOLOGICAL RELATIONSHIPS IN SARGASSUM POLYCERATIUM (PHAEOPHYTA): PHENOTYPIC AND ONTOGENETIC VARIABILITY IN APPARENT PHOTOSYNTHESIS AND DARK RESPIRATION1
Authors: Kilar John A. , Littler Mark M. , Littler Diane S. 
Published: October 2004

ABSTRACTPhenotypic and ontogenetic changes in apparent photosynthesis and dark respiration for Sargassum polyceratium Mont. were related to the differential allocation of resources into blades, stems, vesicles, and fertile branches as well as anatomical parameters of surface area, volume, and blade density from a population in the Content Keys, Florida. Three divergent phenotypes were evaluated during four phases of ontogeny: maximum growth (October), peak reproduction (December), senescence (April), and stasis (July). Photosynthetic and respiratory rates changed throughout the year, at different stages of morphogenesis, and among different phenotypes. Photosynthesis was highest during active growth, decreased during reproduction and senescence, and was lowest during stasis. In contrast, respiration was higher during peak reproduction and stasis. Temporal, phenotypic, and ontogenetic changes in apparent photosynthesis were best explained by interactions among anatomical features, growth stages, and source‐sink relationships of metabolic reserves and pigments. Surface area: volume (SA:V) ratios played a secondary role. Photosynthetic performance of mature axes decreased with the allocation of resources away from blades to air bladders and fertile branches. Apparent productivity and development of fertile branches on phenotypes were not correlated. High respiratory rates, SA:V ratios, blade areas, and low blade densities occurred on developing axes and were consistent with adaptations to low light fields. Sargassum polyceratium, because of its morphological differentiation, is a relatively complex, physiologically variable alga.
CYST FORMATION IN THE RED TIDE DINOFLAGELLATEALEXANDRIUM TAMARENSE(DINOPHYCEAE): EFFECTS OF IRON STRESS1
Authors: Doucette Gregory J. , Cembella Allan D. , Boyer Gregory L. 
Published: October 2004

ABSTRACTThe toxic red tide dinoflagellateAlexandrium tamarense(Lebour) Balech (synonymous withProtogonyaulax tamarensis(Lebour) Taylor) was subjected to iron stress in batch culture over a 24‐day time course. Monitoring of life history stages indicated that iron stress induced formation of both temporary (= pellicular) and resting (= hypnozygotic) cysts. Our experimental induction of sexuality appeared to be associated with iron limitation rather than the total depletion of biologically available iron. Degenerative changes in organelle (i.e. chloroplast, mitochondrion and chromosome) ultrastructure were largely restricted to pellicular cysts, suggesting that these temporary cysts were more susceptible to short‐term iron stress effects than were hypnozygotes. These results are consistent with the hypothesized ecological roles of cysts in maintaining viability over brief (pellicular cysts) and extended (hypnozygotes) exposure to adverse environmental conditions.
CELL SIZE DIFFERENTIATION IN THE BLOOM‐FORMING DINOFLAGELLATEGYMNODINIUMCF.NAGASAKIENSE1
Authors: Partensky Frédéric , Vaulot Daniel 
Published: October 2004

ABSTRACTTwo subpopulations differing essentially by their mean cell size were observed regularly in cultures and natural samples of the naked dinoflagellateGymnodiniumcf.nagasakienseTakayama et Adachi (currently known asGyrodinium aureolumHulburt), a species which frequently forms red tides in North European seas. “Large” cells represented the typical forms; they were morphologically similar to cells of the closely related Japanese speciesG. nagasakiense,which did not form any subpopulation of reduced size. “Small” and “large” cells ofG.cf.nagasakiensehad the same DNA content, but the nucleus of the former appeared to be much more condensed during interphase. Each cell type was able to divide and had its own growth dynamics; therefore, any intermediary between pure populations of “small” and of “large” cells were observed in culture. The “large” form generated a “small” cell by an atypical budding‐like division, whereas the “small” form gave back a “large” form, once it ceased to divide, by simple enlargement of its cell body. Factory inducing cell size differentiation are yet unclear. Neither nitrogen nor phosphorus starvation induced a significant increase in the relative proportion of “small” and budding cells. Although cell size differentiation is associated with the formation of gametes in a variety of dinoflagellates, we demonstrated that “small” cells ofG.cf.nagasakienseare able to divide asexually, in contrast to gametes of most other species. The high proliferative power of “small” cells as compared with normal cells suggests that they could play a significant role during red tides ofG.cf.nagasakiense;in contrast, cells of the Japanese speciesG. Nagasakiensecould sustain high growth rates with larger cell size because this species generally blooms in waters much warmer than those found in northern Europe.
A PHYTOL‐SUBSTITUTED CHLOROPHYLL C FROM EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE)1
Authors: Nelson James R. , Wakeham Stuart G. 
Published: October 2004

ABSTRACTA nonpolar chlorophyll c‐like pigment was isolated by semi‐preparative high performance liquid chromatography from the coccolithophorid Emiliania huxleyi (Lohm.) Hay and Mohler. The visible absorption spectrum of this pigment was similar to that of chlorophyll c2. However, its nonpolar chromatographic properties were quite different from those of the relatively polar chlorophylls c2 and c3 in E. huxleyi and similar to those of chlorophyll a. Analyses by gas chromatography and gas chromatography‐mass spectrometry showed that the nonpolar character of this new chlorophyll c was due to the presence of phytol, most likely on the acid side chain of the porphyrin macro‐cycle. This is the first example of a phytol‐substituted chlorophyll c‐like pigment.
BACTERIAL ASSOCIATIONS WITH MARINE OSCILLATORIA SP. (TRICHODESMIUM SP.) POPULATIONS: ECOPHYSIOLOGICAL IMPLICATIONS1
Authors: Paerly Hans W. , Bebout Brad M. , Prufert Leslie E. 
Published: October 2004

ABSTRACTOn three separate occasions we investigated morphological and physiological aspects of bacterial associations with planktonic aggregates of the ubiquitous marine N2 fixing cyanobacterium Trichodesmium sp. Close associations generally characterized Trichodesmium blooms; associations were present during day‐ and night‐time. Colonization by both rod‐shaped and filamentous heterotrophic bacteria occurred on Trichodesmiun aggregates actively fixing N2 (acetylene reduction). Scanning electron and optical microscopy showed bacteria located both around and within aggregates. Microautoradiography demonstrated that associated bacteria largely mediated utilization of trace additions of 3H‐labeled carbohydrates (fructose, glucose, mannitol) and amino acids, whereas Trichodesmium utilized amino acids only. Oxygen measurements using microelectrodes revealed high localized oxygen consumption among aggregates, with rapid (within a minute) changes from supersaturated to subsaturated oxygen following the transition from photosynthetic illuminated to dark periods. Stab culturing techniques confirmed the presence of heterotrophic N2 fixers among aggregate‐associated bacteria. Parallel deployment of oxygen microelectrodes, the tetrazolium salt 2,3,5 triphenyl tetrazolium chloride (TTC) and acetylene reduction assays demonstrated microaerophilic requirements for expression of nitrogenase activity among cultured bacteria. Trichodesmium aggregates are characterized by dynamic nutrient and oxygen regimes, which promote and maintain simultaneous and contiguous oxygenic photosynthesis and N2 fixation. In part, the above‐mentioned consortial interactions with a variety of heterotrophic bacteria facilitate Trichodesmium biomass production and bloom formation in nitrogen depleted, oligotrophic tropical/subtropical waters.
SUBSTRATUM CONDITIONING AND DIATOM COLONIZATION IN DIFFERENT CURRENT REGIMES1
Authors: Peterson Christopher G. , Stevenson R. Jan 
Published: October 2004

ABSTRACTShort‐term (3 day) diatom colonization of clean ceramic tiles and tiles conditioned with a thin, nonalgal biofilm was examined in fast‐ and slow‐current outdoor experimental stream channels to assess effects of organic conditioning and current regime on diatom colonization. Colonization rates onto unconditioned tiles were 10 times lower in fast current that in slow. Substratum conditioning reduced the effects of current because organic conditioning of tiles significantly enhanced colonization in fast current, but not in slow current. Two diatom taxa (Nitzschia acicularis W. Sm. and Synedra radians Kütz) colonized unconditioned tiles more rapidly than conditioned tiles in slow current, suggesting the existence of negative interactions between these diatoms and bacteria and/or organics in conditioning films.
TAXONOMIC AFFINITIES OF MARINE COCCOID ULTRAPHYTOPLANKTON: A COMPARISON OF IMMUNOCHEMICAL SURFACE ANTIGEN CROSS‐REACTIONS AND HPLC CHLOROPLAST PIGMENT SIGNATURES1
Authors: Shapiro Lynda P. , Haugen Elin M. , Keller Maureen D. , Bidigare Robert R. , Campbell Lisa , L. Guillard Robert R. 
Published: October 2004

ABSTRACTImmunological grouping, determined by affinities of polyclonal antibodies to surface antigens of intact cells, was used to characterize 19 clones of marine coccoid ultraplankton. The resulting cross‐reactive antigen groups corresponded to pigment‐groups as defined by HPLC analysis of chloroplast pigments (carotenoids and chlorophylls). Because immunological cross reactions are specific at the species level in groups of algae having well defined morphological criteria, we suggest that immunological methods can be used to recognize algae presently indistinguishable by standard morphological criteria, and especially in oceanographic applications involving qualitative cell enumerations of the ultraplankton.
Public Attitudes Toward the Census: Influences and Trends*
Authors: Weakliem David , Villemez Wayne J. 
Published: October 2004

Objective. This article considers the determinants of attitudes toward the census.Methods. Data from a survey of Connecticut residents are analyzed. Some of the questions replicate items from previous national surveys.Results. Conservatives and people with low trust in government have more negative views of the census, while interest in politics has no effect. Exposure to advertising has a positive effect on some attitudes.Conclusions. Despite the Census Bureau's efforts to maintain political neutrality, support of the census is influenced by general outlook on government and politics, suggesting that conflicts over the census are likely to continue.
Ignorance in Congressional Voting? Evidence from Policy Reversal on the Endangered Species Act*
Authors: López Edward J. , Sutter Daniel 
Published: October 2004

Objective. In 1978 Congress weakened several key provisions of the Endangered Species Act (ESA), which had been enacted only five years earlier. The objective is to compare alternative explanations for this policy reversal.Methods. Probit and multinomial logit models are used to explain empirically how senators voted in both 1973 and 1978, and to investigate why many senators switched their vote from supporting ESA to weakening it.Results. The findings here indicate that party affiliation and policy‐maker preferences were not important to the 1973 vote, but they were key variables in the 1978 votes and the vote‐switching decision. Proxies for unexpected economic impacts of ESA on individual states have little explanatory power.Conclusions. Ignorance, as measured here, does not appear to explain this policy reversal; rather, an influx of relatively conservative Democrats between 1973 and 1978 presents itself as the leading explanation.