bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF ROCKY INTERTIDAL AMPHIPODS ON ALGAL RECRUITMENT: A FIELD STUDY1
Authors: Buschmann Alejandro H. , Vergara Pedro A. 
Published: October 2004

ABSTRACTEvidence about the potential of mobile marine invertebrates to act as algal spore dispersal agents is presently circumstantial. Using a field correlational and experimental protocol, our study tested the hypothesis that amphipods can increase the spore recruitment of the red algaIridaea laminarioidesBory.Iridaea laminarioidesspore recruitment onto glass slides was measured at a site with high amphipod abundance and a site with low density of amphipods. To evaluate the effect of anUlvacanopy on recruitment, replicated glass slides with and without a surroundingUlvacanopy were installed at both sites. The number ofI. laminarioidesspores recruited on the glass slides was four to eight times higher at the high amphipod abundance site than at the low density site. However, the presence of anUlvacanopy covering the glass slides did not significantly increase the recruitment ofI. laminarioides.Because the abundance ofI. laminarioides, the proportion of cystocarpic plants, and the percentage of open cystocarps only differed slightly between the low and high abundance amphipod sites, we suggest that the variation in recruitment between the sites is due to the differences in amphipod abundance (and their movements) and not to differences in spore production. Moreover, the presence ofI. laminarioidescystocarps showing amphipod grazing scars was significantly higher at the high amphipod density site than at the low density site.
CIRCADIAN REGULATION OF BIOLUMINESCENCE IN THE DINOFLAGELLATE PYROCYSTIS LUNULA1
Authors: Colepicolo Pio , Roenneberg Till , Morse David , Taylor Walter R. , Hastings J. Woodland 
Published: October 2004

ABSTRACTIn the unicellular algae Pyrocystis lunula Schütt and Gonyaulax polyedra Stein, bioluminescence and its circadian regulation are similar in several respects, but there are also several important differences. As in G. polyedra, P. lunula emits light both as bright flashes and as a low intensity glow. At 20° C, the individual flashes are considerably brighter than in G. polyedra, and their durations are typically less than 500 ms. Both species show a circadian rhythm in the frequency of spontaneous flashes, which peaks in the night‐phase under light–dark cycles and continues in both continuous light and dark. However, compared to G. polyedra, the circadian system in P. lunula is more sensitive to light: 10 min exposures (500 μmol · m–2· s–1 white light) can shift the phase of the rhythm by more than 8 h, and rhythmicity is completely suppressed at an irradiance above 20 μmol · m–2· s–1, where the G. polyedra rhythym persists for weeks. Like G. polyedra, period length increases with increasing irradiance of continuous red light but decreases with increasing intensity of continuous blue light. The glow in P. lunula differs markedly from that in G. polyedra in that it occurs at about the same intensity at all times during the circadian cycle; thus, it is not under circadian control but may fluctuate 5–10‐fold in intensity within a time frame of seconds. This suggests that the glow may differ in its physiological basis in the two organisms. The results also indicate that the circadian regulation of luciferase activity differs in the two species. In G. polyedra, the organelle responsible for bioluminescence and luciferase is lost and then reformed on a daily basis; in P. lunula, the luciferase is conserved and localized elsewhere during the nonbioluminescent phase of the cycle.
REVEALING GENETIC MARKERS IN GELIDIUM VAGUM (RHODOPHYTA) THROUGH THE RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) TECHNIQUE1
Authors: Patwary Mohsin U. , MacKay Ron M. , van der Meer John P. 
Published: October 2004

ABSTRACTThe recently developed random amplified polymorphic DNA technique was evaluated as a method for characterizing isolates of the agarophyte Gelidium vagum Okamura. Reaction conditions for single primer polymerase chain reaction were optimized to obtain a high degree of reproducibility of the amplified bands generated from purified G. vagum DNA. A total of 165 primers, including both (A + T)‐ and (G + C)‐rich sequences, was screened for DNA amplification using template DNA from a single Gelidium isolate. None of the 45 (A + T)‐rich primers was positive (i.e. band‐producing). Of the (G + C)‐rich primers, 47 were positive, generating a total of 322 prominent amplification products for DNA from 13 different G. vagum isolates. Polymorphic DNA loci were detected by 37 of the primers. Unweighted pair‐group arithmetic average cluster analysis (UPGMA) of these loci was used to group the G. vagum isolates and thereby determine which were most similar. G. latifolium, used as an out‐group for the UPGMA analysis, showed a high degree of dissimilarity.
THE LIFE CYCLE OE SARGASSUM HORNERI (PHAEOPHYTA) IN LABORATORY CULTURE1
Authors: Uchida Takuji 
Published: October 2004

ABSTRACTThe life cycle of the large dioecious alga Sargassum horneri (Turner) C. Agardh was completed in unialgal culture by controlling photoperiod in relation to the phase of growth. Embryos isolated from a naturally grown female thallus gave rise to early germlings that rapidly formed blades under both short‐day (9 h L) and long‐day (15 h L) conditions at 20° C Shoot elongation, which followed early blade formation, occurred under the short‐day conditions hut not under the long‐day conditions. Functional female and male receptacles developed when thalli 8–14 cm long grown under the short‐day conditions were transferred to the long‐day conditions; gamete fusion occurred when male and female thalli were grown together. Fertilized oospores gave rise to normal thalli in a manner similar to that for in situ plants. Thus, the life cycle of S. horneri was completed in laboratory culture.
RELATIONSHIPS OF SEDIMENTED DIATOM SPECIES (BACILLARIOPHYCEAE) TO ENVIRONMENTAL GRADIENTS IN DILUTE NORTHERN NEW ENGLAND LAKES1
Authors: Anderson Dennis S. , Davis Ronald B. , Ford Mary S. (Jesse) 
Published: October 2004

ABSTRACTLimnological gradients of small, oligotrophic, and low conductance lakes in northern New England were defined by principal components analysis; relationships of sedimented diatom species to the gradients were investigated by correlation analysis. Diatom distributions were most strongly related to the gradient of pH and alkalinity and the covarying variables, conductance, Mg, Ca, total Al, and exchangeable Al. Weaker relationships to lake morphology, dissolved organic carbon and water color, altitude and marine aerosol inputs, and the distinctive water chemistry of some New Hampshire lakes were also present. Results for 16 taxa of importance in our studies of lake acidity are given in detail and are compared to results from other regions of eastern North America. Planktonic taxa were absent below pH 5.5, with the exception of the long form of Asterionella ralfsii var. americana Korn. The two forms of this taxon differed ecologically: the long form (>45μm) had an abundance weighted mean (AWM) pH 4.90 and occurred mostly in lakes that were deep relative to transparency; the short form (<45μm)had an AWM pH and occurred on lakes that were shallow relative to transparency. The ecological advantage of a “splitter” approach to diatom taxonomy was demonstrated by examination of other taxa as well, including Tabellaria flocculosa (Roth) Kütz. These results have important implications for paleolimnological interpretations.
EFFECTS OF TEMPERATURE AND IRRADIANCE ON THE GROWTH OF TWO FRESHWATER PHOTOSYNTHET1C CRYPTOPHYTES1
Authors: Ojala Anne 
Published: October 2004

ABSTRACTEffects of light and temperature on growth of two freshwater photosynthetic cryptophytes of different cell size were studied in batch cultures. For the smaller Cryptomonas 979/67, Steele's model and equation of Platt et al. described the relationship between growth rate and photon flux density (PFD), whereas a hyperbolic tangent function gave a better fit for the larger Cryptomonas 979/62. Maximum growth rates given by the three models were consistent with each other, but the hyperbolic tangent function gave slightly lower estimates. Maximum growth rates in relation to temperature were well described for both species by the model of Logan et al. The optimum temperature for growth for Cryptomonas 979/67 was ca. 24.5° C and 19.0° C for Cryptomonas 979/62. The lethal temperatures were 30.4° C and 23.1° C for 979/67 and 979/62, respectively. The estimated maximum growth rates were 1.38 div.·day−1 for Cryptomonas 979/67 and 0.87 div.·day −1 for Cryptomonas 979/62. There were interspecific differences in photoadaptation strategies, as Cryptomonas 979/67 required relatively high PFDs to show net growth, whereas Cryptomonas 979/62 grew at lower irradiances. Cryptomonas 979/67 showed photoinhibition soon after the saturation point, but Cryptomonas 979/62 tolerated a much wider range of irradiance. From their growth responses to light, Cryptomonas 979/ 67 appears to be a stenotopic and Cryptomonas 979/ 62 a eurytopic strain.
EFFECTS OF NITRATE AVAILABILITY AND IRRADIANCE ON INTERNAL NITROGEN CONSTITUENTS IN CORALLINA ELONGATA (RHODOPHYTA)1
Authors: Vergara Juan J. , Niell F. Xavier 
Published: October 2004

ABSTRACTShort‐term (5‐h) phycobiliprotein photoacclimation was a NO3−, dependent process in the red alga Corallina elongata Ellis et Soland. At low irradianre levels, phycobiliprotein synthesis (both r‐phycocyacin and r‐phycocyanin) took place when N supply was sufficient but was restricted by N limitation. Exposure to saturating irradiance resulted in pigment degradation under N limitation; however, under N‐sufficient conditions a partial r‐phycoerythrin synthesis was observed, despite the repressing role of high photon flux densities on phycobiliprotein synthesis. Soluble protein was less affected than phycobiliprotein by N limitation at low photon flux densities indicating that N limitation stimulates the flow of internal N metabolites toward the synthesis of nonpigmented proteins rather than pigmented proteins.The addition of protein synthesis inhibitors revealed that new phycobiliprotein synthesis occurs in response to sufficient N conditions. When protein synthesis was blocked in the chloroplast and cytoplasm simultaneously (addition of chloramphemcol and cycloheximide), both pigmented and nonpigmented protein synthesis was inhibited. Howeever, when protein systhesis was blocked in the chloroplast, only phycobiliprotein synthesis was clearly inhibited, whereas nonpigmented protein was less affected, indicating that phycobiliprotein is the main fraction of protein synthesized in the chloroplast at low photon flux densities when external N is available. This inhibition of phycobiliprotein synthesis was consistent with a maximal increase in metabolites of protein synthesis (internal NH4+ and amino acids).Our results suggest that phycobiliproteins may be an important N reservoir to meet internal N demands during N limitations in C. elongata. Moreover, r‐phycoerythrin, synthesized even at saturating irradiance levels, and the major constituent of the phycobiliprotein pigments, may be more sensitive to changes in N supply than r‐phycocyanin. The influence of limited irradiance levels on N assimilation and the effects of repressing protein synthesis on internal N accumulation are also discussed.
A MODIFIED CELL WALL MUTANT OF THE RED MICROALGA RHODELLA RETICULATA RESISTANT TO THE HERBICIDE 2,6‐DICHLOROBENZONITRILE1
Authors: Arad Shoshana (Malis) , Dubinsky Ofer , Simon Bracha 
Published: October 2004

ABSTRACTThe rigid component of the cell walls of red macroalgae, cellulose, is lacking in the red microalgae. Instead, the cells are encapsulated within an amorphous polysaccharide. These complex sul fated polysaccharides are composed of at least 10 different sugars, but their structure is not known, When the herbicide 2,6‐dichlorobenzonitrile (DCB), a compound that specifically inhibits cellulose biosynthesis, was applied to cultures of the red microalga Rhodella reticulata upon inoculation, growth was inhibited. When added during the stationary phase of growth (after cell division had ceased), DCB did not affect cell number but it did inhibit polysaccharide production. A spontaneous mutant resistant to DCB was selected; it had physiological characteristics similar to those of the wild‐type parent. The composition of the cell wall polysaccharide of the mutant was totally modified, being composed almost entirely (98% of its dry matter, as compared to 2.9% in the wild type) of methyl galactose, but retaining the same sulfate content. The molecular mass of the mutant polysaccharide was, however, similar to that of the wild‐type parent (∼6 × 106 daltons), although its viscosity was significantly lower.
CHROMOSOMES AND DNA IN SYMBIODINIUM FROM AUSTRALIAN HOSTS1
Authors: Udy James W. , Hinde Rosalind , Vesk Maret 
Published: October 2004

ABSTRACTChromosome counts are reported for five species of Symbiodinium Freudenthal isolated from the host species Plesiastrea versipora, Aiptasia pulchella, Parerythropodium sp., Zoanthus robustus, and Capnella gaboensis based on light and electron microscope studies. Both techniques resulted in large variations in the apparent numbers of chromosomes per nucleus in Symbiodinium isolated from the same host colony. Adjacent regions of condensed DNA were occasionally linked by thin fibrils of DNA, The results suggest that the regions of condensed nuclear DNA in dinoflagellates may not represent whole chromosomes, and so chromosome counts are considered inappropriate for defining Symbiodinium taxa.
INHIBITION OF FERTILIZATION IN FUCUS (PHAEOPHYCEAE) BY A MONOCLONAL ANTIBODY THAT BINDS TO DOMAINS ON THE EGG CELL SURFACE1
Authors: Stafford Christopjher J , Callow James A. , Green Jonathan R. 
Published: October 2004

ABSTRACTFertilization in the brown alga Fucus serratus L. involves interactions between sperm and eggs and in species‐specific. Recent results with monoclonal antibodies(MAbs FS4 and FS5) that recognize glycoproteins on the Fucus egg cell surface have shown that different sets of glycoproteins are organized into distinct domains. Thus, regions on the egg surface are FS4+FS5− and FS4−FS5+, and some smaller regions are FS4+FS+. To determine functional differences between these domains, MAbs FS4 and FS5 were included in a fertilization assay, Purified FS5 antibody, which is an immunoglobulin class M (IgM), inhibited fertilization, whereas FS4 IgM had no effect, Fragment antigen‐binding fragment, which suggests that the effects were not due to steric hindrance by large IgM molecules or to cross‐linking of receptors. FS5 inhibited fertilization in both F. serratus and F. vesiculosus; therefore, its effect was not species‐specific, Thus we show that there is functional heterogeneity of the Fucus egg cell surface and compare our results to previous reports on inhibitory effects of lectins, Overall, the evidence suggests that there may be two levels of interaction between gametes in Fucus involoving nonspecific and species‐specific binding.
ULTRASTRUCTURE OF CHRYSODIDYMUS SYNUROIDEUS (SYNUROPHYCEAE)1
Authors: Graham Linda E. , Graham James M. , Wujek Daniel E. 
Published: October 2004

ABSTRACTA clonal isolate of Chrysodidymus synuroideus Prowse was derived form a Sphagnum bog in northern Wisconsin and maintained in culture for over 3 years. Cultured colonies consisted almost exclusively of two cells attached at the posterior, each cell bearing two unequal flagella. Correlative light and electron microscopic observations revealed that colonies composed of smaller, ovate cells represented more recent products of cell division, while colonies of elongate cells were more mature. These results support previous taxonomic conclusions, based on light microscopic observations, of field‐collected specimens and body scale ultrastructure, that Chrysodidymus is a valid genus, and that two species described by Prowse on the basis of cell size differences, should be merged. In addition, ultrastructural studies of cultured Chrysodidymus demonstrated that this genus is a member of the Synurophyceae on the basis of characters related to flagellar morphology, basal body arrangement, and cytoskeletal ultrastructure. Chrysodidymus synuroideus resembles Synura sphagnicola in body scale structure, the presence of distinctive linear or clavate scales on both flagella, a relatively loose scale case, and acidophilic habital, Unlike S. sphagnicola, Chrysodidymus has no Pyrennoids, Peripheral (rather than axial) plastids, and a single posterior storage vesicle (rather than two peripheral storage vesicles).
ASEXUAL AND SEXUAL REPRODUCTION IN GONIUM QUADRATUM (CHLOROPHYTA) WITH A DISCUSSION OF PHYLOGENETIC RELATIONSHIP WITHIN THE GONIACEAE1
Authors: Nozaki Hisayoshi 
Published: October 2004

ABSTRACTMorphological details of asexual and sexual reproduction in Gonium Quadratum Pringsheim ex Nozaki (Goniaceae, Chlorophyta) were observed by light microscopy, based on clonal cultured materials originating from Nepal. In asexual reproduction, the alga exhibited two different patterns of cell cleavage during formation of 8‐and 16‐celled daughter colonies. Sexual reproduction was heterothallic and isogamous. The gametes bore a tubular mating structure (bilateral mating papilla) at the base of the flagella, and the papillae of the two gametes. The germinating zygote gave rise to four biflagellate gone cells joined in a colony (germ colony). Possible phylogenetic relationships within the Goniaceae at the species level are outlined, mainly on the basis of reproduction characteristics.
PRODUCTION OF AXENIC CULTURES OF MICROMONAS PUSILLA (PRASINOPHYCEAE) USING ANTIBIOTIC 1
Authors: Cottrell Matthew T. , Suttle Curtis A. 
Published: October 2004

ABSTRACTBacteria‐free cultures of the prasinophyte Micromonas pusilla (Butcher) Monton and Parke, UTEX LB 991, were produced by intially determining the effects of several antibiotics on the growth of this alga and then using a combination of these antibiotics to eliminate associated bacteria, Micrononas pusilla was resistant ot penicillin G, neomycin, gentamicin and streptomycin at bactericidal concentrations but sensitive to chloramphenicol and polymixin B. Passage of M. pusilla through the sequence of antibioties penicillin G → neomycin → gentamician → kanamycin resulted in an axenic culture of M, pusilla this method should be suitable for producing axenic culture of other strains of M. pusilla.
PHYSIOLOGICAL ACCLIMATION OF MARINE PHYTOPLANKTON TO DIFFERENT NITROGEN SOURCES1
Authors: Levasseur Maurice , Thompson Peter A. , Harrison Paul J. 
Published: October 2004

ABSTRACTWe examined the energetic dependency of the biochemical and physiological responses of Thalassiosira pseudonana Hasle and Heimdal. Chaetoceros gracilis Schütt, Dunaliella tertiolecta Butcher, and Gymnodinium sanguineum Hirasaka to NH4+, NO3−, and urea by growing them at subsaturating and saturating photon flux (PF). At subsaturating PF, when energy was limiting, NO3− and NH4+ grown cells had similar growth rates and C and X quotas. Therefore, NO3− grown cells used up to 48% more energy than NH4+ grown cells to assimilate carbon and nitrogen. Based on our measurements of pigments, chlorophyll‐a‐specific in vivo absorption cross‐section, and fluorescence‐chlorophyll a−1, we suggest that NO3−, grown cells do not compensate for the greater energy requirements of NO3− reduction by trapping more light energy. At saturating PF, when energy is not limiting, the utilization of NO3−, compared to NH4+ resulted in lower growth rates and N quotas in Thalassiosira pseudonana and lower N quotas in Chaetoceros gracilis, suggesting enzymatic rather than energetic limitations to growth. The utilization of urea compared to Nh4+ resulted in lower growth rates in Chaetoceros gracilis and Gymnodinium sanguineum (saturating PF) and in lower N quotas in all species tested at both subsaturating and saturating PF. The high C:N ratios observed in all urea‐grown species suggest that nitrogen assimilation may be limited by urea uptake or deamination and that symptoms of N limitation in microalgae may be induced by the nature of the N source in addition to the N supply rate. Our results provide new eridence that the maximum growth rates of microalgae may be limited by enzymatic processes associated with the assimilation of NO3−, or urea.
THF INFLUENCE OF IRRADIANCE ON THF BIOCHEMICAL COMPOSITION OF THE PRYMNESIOPHYTE ISOCHRYSIS SP. (CLONE T‐ISO)1
Authors: Brown Malcolm R. , Dunstan Graeme A. , Jeffrey S. W. , Volkman John K. , Barrett Stephanie M. , LeRoi Jeannie‐Marie 
Published: October 2004

ABSTRACTThe effects of irradiance on the biochemical composition of the prymnesiophyte microalga, Isochrysis sp. (Parke; clone T‐ISO), a popular species for mariculture, were examined. Cultures were grown under a 12:12 h light: dark (L:D) regime at five irradiances ranging from 50 to 1000 μE·m 2·s−1 and harvested at late‐logarithmic phase for analysis of biochemical composition. Gross composition varied aver the range of irradiances. The highest levels of protein were present in cells from cultures grown at 100 and 250 μE·m 3·s1, and minimum levels of carbohydrate and lipid occurred at 50 μE·m−2·s−1. Because the cell dry weight was reduced at lower irradiances, different trends were evident when results were expressed as percentage of dry weights. Protein percentages were highest at Wand 100 μE·m−2·s−1 and carbohydrate at 100 μE·m−2·s−1.The composition of amino acids did not differ over the range of irradiances. Glutamate and aspartate were always present in high proportions (9.0–13.5%); histidine. methionine, tryptophan, cystine, and hydroxy‐proline were minor constituents (0.0–2.6%). Glucose was the predominant sugar in all cultures, ranging from 23.0% (50 μE·m−2·s−1) to 45.0% (100 μE·m−2·s−1) of total polysaccharide. No correlation was found between the proportion of any of the sugars and irradiance.The proportions of the lipid class components and fatty acids showed little change with irradiance. The main fatty acids were 14:0, 16:0, 16:1(n‐7), 18:1(n‐9), 18:3(n‐3). 18:4(n‐3), 18:5(n‐3), and 22:6(n‐3). Proportions of 22: 6(n‐3) increased, whereas l8:3(n‐3). 18:3(n‐6). and 18:4(n‐3) decreased, with increasing irradiance. Pigment concentrations were highest in cultures grown at 50 μE·m−2·s−1, except for fucoxanthin and diadinoxanthin (100 μE·m−2·s−1). The concentrations of accessory pigments correlated with chlorophyll a, which decreased in concentration with increasing irradiance.On the basts of biochemical composition, an irradiance of 100 μE·m−1·s−1 (12:12 h L:D cycle)for the culture of Isochrysis sp. (clone T‐ISO) may provide optimal nutritional value for maricultured animals, although feeding trials are now necessary to substantiate this.