bluuebunny/crossref_metadata_2025_split huggingface dataset:
MERCURY AND TEMPERATURE INTERACTIONS ON THE GROWTH RATES OF THREE SPECIES OF FRESHWATER PHYTOPLANKTON1,2
Authors: Knowles Sally C. , Zingmark Richard G. 
Published: April 2006

ABSTRACTCultures of freshwater algae, representing three algal divisions, Synura petersenii Korshikov; Chlamydomonas sp.: and Nitzschia sp., were subjected to four different mercury‐temperature shock interactions to demonstrate synergistic effects between mercury and temperature. Algal growth, measured by temporal changes in vivo fluorescence of chlorophyll was used to ascertain the effects. Mercury addition and temperature shock had various inhibitory effects on algal growth. Prior environmental conditions influence the effect of subsequent treatments. Growth of S. petersenii was severely inhibited by mercury in all experiments. Control cultures would not grow at 30 C and died when shacked at this temperature. Chlamydomonas sp. cultures initially inhibited by mercury were able to recover under most conditions after a period of reduced growth. Nitzschia sp. was resistant to mercury except when simultaneously shocked with temperature. Mercury analyses showed that Nitzschia cells at 25 C and 30 C contained a high percentage of the mercury initially added to the cultures. There was a significant loss of mercury at the end of each experiment from all cultures, probably due to volatilization.
ACUTE TOXICITY OF SOME BLUEGREEN ALGAE TO THE PROTOZOAN PARAMECIUM CAUDATUM1
Authors: Ransom Randall E. , Nerad Thomas A. , Meier Peter G. 
Published: April 2006

ABSTRACTFour species of bluegreen algae were tested for possible effect on the protozoan Paramecium caudatum Ehrenberg. Toxicity was demonstrated using lyophilized cells of Fischerella epiphytica Ghose and Gloeotrichia echinulata (Smith) Richter. Nostoc linckia (Roth) Bornet & Thuret failed to show any effects when lyophilized but became toxic when sonified. Anabaena flos‐aquae (Lyngb.) Bréb. was nontoxic in all tests. G. echinulata was lethal at 0.1 mg·ml−1 which is comparable to the toxic concentration of Aphanizomenon flos‐aquae (L.) Ralfs reported for microcrustaceans.
FATTY ACID DYNAMICS IN THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE): IMPLICATIONS FOR P HYSIOLOGICAL ECOLOGY1,2,3
Authors: Fisher Nicholas S. , Schwarzenbach René P. 
Published: April 2006

ABSTRACT The growth dry weight, fatty acid weight and fatty acid composition of two clones of Thalassiosira pseudonana Hasle & Heimdal were measured under several growth conditions. Determinations of total cellular fatty acids were made using chemical ionization mass spectrometry. Both clones had the same fatty acids, dominated by C14:0, C16:0, C16:1, C16:3, C16:4, C18:4 and C20:5, though in different relative amounts. Fatty acids typically represented 5–10% the dry weight of a cell during log Phase growth and up to 22% during stationary Phase. The C16 fatty acids of both clones changed as the cultures aged, though much more markedly in the Sargasso Sea done (13–1) than in the estuarine one (3H). The C16:0 and C16:1 acids of both clones declined sharply in the dark and were replenished in the light. Cells maintained in constant illumination, but with no cell division. produced large quantities of these acids. Cells of done 13–1 treated with polychlorinated biphenyl (PCB) initially grew more slowly than control cells, weighed more, and had higher relative amounts of C16:0 and C16:1. Fatty acid studies may provide useful indicators of ecologically important energy reserves and membrane adaptations in the algae.
STICTOCYCLUS STICTODISCUS (BACILLARIOPHYTA): COMMENTS ON ITS ECOLOGY, STRUCTURE AND CLASSIFICATION1,2
Authors: Round Frank E. 
Published: April 2006

ABSTRACT The rarely studied large diatom Stictocyclus stictodiscus (Grun.) R. Ross has been investigated by light and electron microscopy. Confusion over the classification of this diatom has been reduced, and it has been assigned to a new family, Stictocyclaceae, though the relationship of this to the overall classification of centric diatoms is still not clear.
TRANSLOCATION OF 14C IN MACROCYSTIS INTEGRIFOLIA (PHAEOPHYCEAE)1,2
Authors: Lobban Christopher S. 
Published: April 2006

ABSTRACT Translocation patterns in the giant kelp, Macrocystis integrifolia Bory, were investigated in situ using 14C tracer; sources and sinks were identified. Export was first detected after 4 h of labeling; experiments were routinely 24 h continuous 14C application. Mature blades exported 14C to young blades on the same frond and on younger fronds, as well as to sporophylls and frond initials at the bases of the fronds. Blades <0.3 m from the apex imported and did not export; this distance did not change seasonally. In spring export from blades 0.3–1.25 m from the apex was exclusively upwards; older blades also exported downwards. In fall downward export began 0.5 m from the apex, and blades >2 m from the apex exported exclusively downwards. Carbon imported by frond initials, young fronds, and sporophylls in fall may partly be stored for growth in early spring. No translocation was seen in very young plants until one blade (secondary frond initial) bad been freed from the apical blade; this blade exported to the apical blade for a time, but imported when it began to develop into a frond. The second and third formed blades on the primary fronds (sporophylls also exported when <0.3 m from the apex, and later stopped. Frond initials and sporophylls on later‐formed fronds did not export at all. The translocation pattern in M. integrifolia differs from that previously reported in M. pyrifera in seasonal change and in distances from the apex at which the changes take place.
PURIFICATION OF RIBULOSE 1,5‐BISPHOSPHATE CARBOXYLASE AND CARBON ISOTOPE FRACTIONATION BY WHOLE CELLS AND CARBOXYLASE FROMCYLINDROTHECASP. (BACILLARIOPHYCEAE.)1,2,3
Authors: Estep Marilyn F. , Tabita F. Robert , Baalen Chase Van 
Published: April 2006

ABSTRACTRibulose 1,5‐biphosphate carboxylase has been purified to homogeneity from extracts ofCylindrothecasp. (strain N‐1), a marine, pennate diatom. The carboxylase has a molecular weight and structural composition similar to the enzyme from higher plants. When assayed in the presence of 1 mM NaHCO3the enzyme was stimulated nearly 40% by 1 mM aspartate and over 20% by 1 mM malate, and was inhibited to over 60% by 1 mM phosphoenolpyruvate. Similar experiments, using spinach carboxylase, failed to show activation by these metabolites. When assayed in the presence of 20 mM NaHCO3, 6‐phosphogluconate (1 mM) inhibited activity of ribulose bisphosphate carboxylase from Cylindrothecaby 60%, and higher concentrations of maiate (10 mM) inhibited activity by 25% Carbon isotope fractionation by ribulose bisphosphate carboxylase was ‐32.6% (ppt) when measured under N2using homogeneous enzyme, whereas maximum carbon isotope fractionation by the whole alga grown in 1% ‐C02‐in air averaged ‐ 16.8%. Carbon isotope fractionation by the whole alga varied with the density of the culture and was maximum at a low cell density (1.7 ± 106cellslml). At higher densities, the fractionation decreased by 4.0%. Carbon isotope fractionation has been used previously to determine the pathway of carbon metabolism in other organisms; the results of this investigation seem to indicate that this strain uses both the reductive pentose phosphate pathway and the C4carbon pathway for primary CO2fixation.
EFFECTS OF NITRATE CONCENTRATION ON THE GROWTH AND PHYSIOLOGY OF LAMINARIA SACCHARINA (PHAEOPHYTA) IN CULTURE1,2
Authors: Chapman A. R. O. , Markham J. W. , Lüning K. 
Published: April 2006

ABSTRACTLaminaria saccharina Lamour. sporophytes were grown in enriched and synthetic media through a range of nitrate concentrations, There was an approximately linear relationship between growth and nutrient concentration up to 10 μ substrate concentration. The half‐saturation constant (K2) was ca. 1.4 μ NO3‐. The internal levels of NO3‐ increased at substrate concentrations above 10 μM b>3‐ and reached levels several thousand times higher than the surrounding medium. Thus there is evidence for luxury consumption of NOsb>3‐. The chlorophyll content and photosynthetic capacities of plants also increased with increasing external NO3‐ The ecological implications of this work are considered.
HYBRIDIZATION OF MACROCYSTIS (PHAEOPHYTA) WITH OTHER FLOAT‐BEARING KELPS1,2
Authors: Sanbonsuga Yoshiaki , Neushul Michael 
Published: April 2006

ABSTRACT Sporophytes were produced in 22 out of 23 attempts to cross Macrocystia angustifolia Bory with Pelagophycus porra (Lemon) Setchell. Representative samples of these plants were raised in a surge‐tank under greenhouse conditions to several meters in length. The plants resulting from this intergeneric cross were intermediate in morphology between the parental genera. The intermediate plants were similar to those found fry one of the authors (MN) in 1957, and by others since then, in California kelp beds where Macrocystis and Pelagophycus co‐occur, A cross between M. angustifolia and Nereocystis luetkeana (Mertens) P. & R., also produced normal sporophytes. The taxonomic, evolutionary, morphogenetic and genetic implications of these hybridizations are discussed.
CHLOROPLAST STRUCTURAL CHANGES INDUCED BY WHITE LIGHT IN THE MARINE DIATOMSTEPHANOPYXIS TURRIS1,2
Authors: Jeffrey S. W. , Vesk Maret 
Published: April 2006

ABSTRACTThe intensity of white tight used for growingStephanopyxis Turris(Grev.) Ralfs affects the structure of the chloroplasts. In particular, the conformation of the thylakoids, within the bands is altered by increasing the intensity. At low light (100 μW.cm‐2, 12:12 LD cycles) the thylakoids are generally parallel, whereas at 500 μW.cm‐2the thylakoids tend to be twisted and out of plane. The possible significance of these conformational changes is discussed.
UNEXPECTED RESPONSE TO VITAMIN B12OF DOMINANT CENTRIC DIATOMS FROM THE SPRING BLOOM IN THE GULF OF MAINE (NORTHEAST ATLANTIC OCEAN)1,2
Authors: Swift Dorothy G. , Guillard Robert R. L. 
Published: April 2006

ABSTRACTTwelve clones (seven species) representative of centric diatoms dominant in the spring phytoplankton bloom in the Gulf of Maine were isolated and rendered axenic. Genera included wereThalassiosira, PorosiraandChaetoceros.Unlike most centric diatoms studied previously, none of these has an absolute requirement for vitamin B12.However, B12(5ng.l‐1) stimulated growth of most clones by eliminating or reducing the lag phase and increasing the growth rate. Bloom population densities developed 4–54 days earlier with B12present. Several clones grown with B12removed more than 80% of the vitamin from the medium. When grown in vitamin‐free medium the cells put 0.01–0.7 ng.l‐1B12into the medium. We conclude that vitamin B12is of ecological significance even though the requirement for it is not absolute.
EXCRETION OF GLYCOLATE BY A SPECIES OF CHLORELLA (CHLOROPHYCEAE)1
Authors: Colman Brian 
Published: April 2006

ABSTRACT The claim that Chlorella sp. (CCAP 211/8p), sometimes referred to as C. fusca, Shihira and Krauss, does not excrete glycolate has been reexamined. Chlorella sp. grown on 5% CO2in air, excreted glycolate when incubated in light in 10 mM bicarbonate. Excretion ceased 30–60 min after transfer of the cells to air and no excretion could be detected with air‐grown cells or with cells grown on 5% CO2in media buffered at pH 8.0. Incubation with 10 mM isonicotinyl hydrazide, a glycolate pathway inhibitor, caused excretion in air‐grown cells and stimulated excretion in CO2‐grown cells indicating that both the rate of glycolate synthesis and metabolism is higher in CO2grown cells than in air‐grown cells. Enhanced glycolate synthesis and excretion in CO2‐grown cells is correlated with law photosynthetic rate in 10 mM bicarbonate, and the photosynthetic rate of these cells doubles over a period of 2–2.5 h after initial transfer from high CO2to bicarbonate. This correlation of photosynthetic induction with cessation of glycolate excretion is similar to that reported in a bluegreen alga and thought to occur in other green algae. These results indicate that glycolate excretion and its regulation in this species of Chlorella is not different from that in other algae.
MITOSIS AND CYTOKINESIS INASTEROMONAS GRACILIS, A WALL‐LESS GREEN MONAD1
Authors: Floyd Gary L. 
Published: April 2006

ABSTRACTAsteromonas gracilisArtari remains motile throughout cell division. Basal bodies separate and replicate at prophase. They are located lateral to the poles of the closed metaphase spindle. Kinetochores appear at late metaphase. Chromosomes move to the poles and extensions of the nuclear envelope develop into the pyrenoid at anaphase. The interzonal spindle disintegrates at telophase and a diffuse phycoplast is present. Cytokinesis proceeds rapidly from the anterior region of the cell. Newly formed daughter cells have four narrow‐banded rootlets and both distal and proximal fibers connect the basal bodies. Features of cell division inAsteromonasare compared to those in other algae, particularlyDunaliellaandChlamydomonas.
UPTAKE OF INORGANIC NITROGEN BY CODIUM FRAGILE SUBSP. TOMENTOSOIDES (CHLOROPHYTA)1
Authors: Hanisak M. Dennis , Harlin Marilyn M. 
Published: April 2006

ABSTRACT The uptake of nitrate, nitrite and ammonium by Codium fragile subsp. tomentosoides (van Goor) Silva was measured at different combinations of temperature (6–30 C) and irradiance (0–140 μEin.m‐2. s‐1). Uptake of all three forms of N was greater at 12–24 C than at 6 and 30 C. Although uptake was stimulated by light, saturation occurred at relatively low irradiance (7–28 μEin m‐2 s‐1, depending on the N source and temperature). The Michaelis‐Menten uptake constants (Vmax K)varied with temperature. Vmax was greatest at intermediate temperatures and K was lowest at lower temperatures. The Vmaxfor NH4+ was higher and the K, for NH4+was lower than those for NO3‐‐ and NO2‐‐. Codium was capable of simultaneously taking up all three forms of inorganic N although the presence of NH4+ reduced the uptake of both NO3‐‐ and NO2‐‐. The results of this study indicate that part of the ecological success of Codium in a N‐limited environment may be due to its N uptake capabilities.
FLUCTUATIONS IN FREE AMINO ACID POOLS OFGYMNODINIUM SIMPLEX(DINOPHYCEAE) IN RESPONSE TO AMMONIA PERTURBATION: EVIDENCE FOR GLUTAMINE SYNTHETASE PATHWAY1,2
Authors: Turpin David H. , Harrison Paul J. 
Published: April 2006

ABSTRACTAn ammonia limited chemostat culture ofGymnodinium simplex (Lohm.) Kofoid & Swezy was perturbed with ammonia and fluctuations in the free intracellular amino acid pools were followed 80 min. The steady‐state value of glutamate was 2.07 ± 10‐15mol cell‐1and of glutamine was 0.31 ± 10‐15mol cell‐1. Five minutes after the perturbation, a substantial rise in glutamine was observed with a corresponding decrease in glutamate. This is considered a result of glutamine synthetase acting as the primary ammonia assimilating enzyme. The level of ammonia and the major free amino acids reached a maximum 10 min after the perturbation and then slowly decreased.
NITRATE UPTAKE BY LAMINARIA LONGICRURIS (PHAEOPHYCEAE)1,2
Authors: Harlin Marilyn M. , Craigie J. S. 
Published: April 2006

ABSTRACTLaminaria longicrucis De la Pylaie took up exogenous nitrate under both summer and winter conditions. During July and August no NO3‐ was detected in the ambient water or in algal tissues although it was present in both in February. Discs (2.3 cm diam.) of thin blade tissue were incubated with NO3‐ at four temperatures, with and without illumination. Similar values Jor NO3‐ uptake were found for both summer and winter collected plants when measured in light at 0 C. An apparent K of 4–6 μM was recorded for both types of plants; the Vmax ranged from 7 to 10 μmol h‐1 g‐1 dry wt measured in ca. 1800 μW cm‐2 of cool‐white fluorescent light. Uptake rates at 5 C were 66%, and at 0 C 30% of those for controls run at 15 C. The alga scavenged NO3‐ from solutions <0.5 μM. Ammonia did not inhibit NO3‐ uptake. Antibiotic pretreatment reduced NO3‐ uptake by a maximum of 12%. Nitrite uptake was inhibited in proportion to the concentration of NO3‐ in the medium.
SPECTROPHOTOMETRICALLY ASSAYED INHIBITORY EFFECTS OF MERCURIC COMPOUNDS ONANABAENA FLOS‐AQUAEANDANACYSTIS NIDULANS(CYANOPHYCEAE)1
Authors: Thomas Dempsey L. , Mantes Joseph G. 
Published: April 2006

ABSTRACTThe growth‐related inhibitory effects of mercuric chloride(MC),methylmercuric chloride (MMC) and phenylmercuric acetate (PMA) (each at 1, 10, 10,2103ppb) were measured inAnabaena flos‐aquae (Lyng.) Bréb. and Anacystis nidulans(Richt.) Drouet&Daily. Optical density changes of control cultures compared against those of experimental cultures showed that MC was the least inhibitory of the compounds. MMC. was the most inhibitory, producing statistically significant inhibition at a concentration as low as I ppb inAnabaena.PMA was more inhibitory than MC but less than MMC. Effects caused by the mercury compounds included bleaching of individual cells, cell size changes and destruction of whole cells; the degree and extent of these effects depended on the compound and its concentration in the nutrient medium. The high sensitivities of the algae tested suggested the possibility of using them as test organisms in bioassays for mercury.
CHRYSOCHROMULINA BREVITURRITA SP. NOV., A NEW FRESHWATER MEMBER OF THE PRYMNESIOPHYCEAE1
Authors: Nicholls Kenneth H. 
Published: April 2006

ABSTRACTChrysochromulina breviturrita sp. nov. is described as a new haptonema‐bearing member of the freshwater Prymnesiophyceae. It is ca. three times larger than the only other known freshwater member of the genus (C. parva Lackey)and possesses a haptonema only ca. 0.2–0.3 as long as the haptonema of C. parva. Two equal flagella (1.5–2 as long as the haptonema), a large contractile vacuole, two parietal plasties, a single pyremid, nucleus, Chrysolaminarin‐like droplets and a food vacuole are features readily observed with the light microscope. Dried and shadoweast whole mounts examined with the electron microscope reveal the cell surface covered with two types of small, delicate scales: outer spined scales with a clubshaped terminus and with the spine anchored to a circular to oval base‐plate by 2–6 (7) branching arms; and, spineles oval plate scales with concentric lines and radiating ridges on one face and parallel ridges on the other. C. breviturrita has been found in nine lakes in Ontario (Canada). Pereliminary observations suggest that it is an important component of lake plankton and has probably not been delected in previous work, more because of its fragility than because of its scarcity. Living specimens are a prerequisite for initial identification, since cells frequently rupture and haptonemata are often lost when the organisms are killed with the commonly used fixatives.
PATTERNS OF ALGAL SUCCESSION IN A PERTURBATED MARINE INTERTIDAL COMMUNITY1
Authors: Murray Steven N. , Littler Mark M. 
Published: April 2006

ABSTRACTPatterns of algal succession for a sewage‐polluted and an unpolluted habitat near Wilson Cove, San Clemente Island, California, were studied from December 1974 to June 1977. Resident populations were analyzed for 56 fully denuded and 34 undisturbed control quadrats during 11 assessment periods. The denuded quadrats in the perturbated (polluted) habitat showed recovery within 1.0 mo as determined by cover, percent similarity and species diversity comparisons with control plots. The short recovery times of the algal populations dominating the perturbated habitat indicate that these species maintain relatively constant overall abundances due to their potential for rapid recruitment and growth. Denuded quadrats in the unpolluted habitat did not show recovery even after 30.0 mo. These quadrats were dominated during the first 1.3 mo by algae characteristic of the perturbated area, including filamentous Ectocarpaceae, colonial diatoms and bluegreen algae. Petalonia fascia (Müll.) Kuntze (1.3–3.0 mo), and Scytosiphon lomentaria (Lyngb.)J. Ag. and Colpomenia sinuosa (Roth) Derb. & Sol. (1.3–5.0 mo) were abundant shortly following plot denudation and provided thick growths that may have excluded other algae. The similarity between the species occupying the sterilized plots during the first few months and those that provide the majority of cover in the perturbated area supports the hypothesis that the dominant algae of the upper and midintertidal regions of this habitat consist largely of early successional or opportunistic species with high capacities for growth and reproduction. Additionally, these experiments suggest that algal populations described for other perturbated epilithic systems also represent resilient subclimax associations.
SURVEY OF SWIMMING POOL ALGAE OF THE PHOENIX, ARIZONA, METROPOLITAN AREA1
Authors: Adamson Richard P. , Sommerfeld Milton R. 
Published: April 2006

ABSTRACT Thirteen genera of algae were collected and identified from 110 swimming pools in the metropolitan area of Phoenix, Arizona. They included seven cyanophytes (Calothrix, Lyngbya, Oscillatoria, Nostoc, Phormidium, Plectonema, Pleurocapsa), four chlorophytes (Chlamydomonas, Diogenes, Oocystis, Roya), and two chrysophytes (Pleurochloris, Nitzschia). Pleurochloris pyrenoidosa Pascher was the most common swimming pool alga, occurring in 67% of the pools sampled. Species of Phormidium and Plectonema were the next most abundant, with species of Chlorophyta least common, occurring in less than 5% of the swimming pools surveyed. Algae occurred in swimming pools under a wide range of physicochemical conditions. A correlation between physicochemical parameters monitored and the appearance of a particular algal species was not evident.
QUANTITATIVE CHARACTER ANALYSIS FOR A NEW VARIETY OF SYNEDRA CYCLOPUM (BACILLARIOPHYCEAE)1
Authors: Cunningham Gregg A. , Whitson Paul D. 
Published: April 2006

ABSTRACT Two morphotypes of Synedra cyclopum Brutschy obtained from two depths and time periods at Lake West Okoboji, Iowa, were quantitatively analyzed for value character similarity. Analysis and comparison with earlier collections demonstrate sufficiently stable characters to describe a new variety. A description and Latin diagnosis of the new variety S. cyclopum var. incisa Cunningham is presented.
Effect of Gender on Communication of Health Information to Older Adults
Authors: Dearborn Jennifer L. , Panzer Victoria P. , Burleson Joseph A. , Hornung Frederick E. , Waite Harrison , Into Frances H. 
Published: April 2006

OBJECTIVES: To examine the effect of gender on three key elements of communication with elderly individuals: effectiveness of the communication, perceived relevance to the individual, and effect of gender‐stereotyped content.DESIGN: Survey.SETTING: University of Connecticut Health Center.PARTICIPANTS: Thirty‐three subjects (17 female); aged 69 to 91 (mean±standard deviation 82±5.4).MEASUREMENTS: Older adults listened to 16 brief narratives randomized in order and by the sex of the speaker (Narrator Voice). Effectiveness was measured according to ability to identify key features (Risks), and subjects were asked to rate the relevance (Plausibility). Number of Risks detected and determinations of plausibility were analyzed according to Subject Gender and Narrator Voice. Narratives were written for either sex or included male or female bias (Neutral or Stereotyped).RESULTS: Female subjects identified a significantly higher number of Risks across all narratives (P=.01). Subjects perceived a significantly higher number of Risks with a female Narrator Voice (P=.03). A significant Voice‐by‐Stereotype interaction was present for female‐stereotyped narratives (P=.009). In narratives rated as Plausible, subjects detected more Risks (P=.02).CONCLUSION: Subject Gender influenced communication effectiveness. A female speaker resulted in identification of more Risks for subjects of both sexes, particularly for Stereotyped narratives. There was no significant effect of matching Subject Gender and Narrator Voice. This study suggests that the sex of the speaker influences the effectiveness of communication with older adults. These findings should motivate future research into the means by which medical providers can improve communication with their patients.