bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE UPTAKE OF IODATE BY MARINE PHYTOPLANKTON1
Authors: Moisan Tiffany A. , Dunstan William M. , Udomkit Ajcharaporn , Wong George T. F. 
Published: October 2004

ABSTRACTSeveral studies have suggested that phytoplankton play a role in the iodine cycle. Using a short‐term incubation technique for determining the uptake of iodate by phytoplankton, cultures of Thalassiosira oceanica Hasle, Skeletonema costatum (Greville) Cleve, Emiliania huxleyi (Lohmann) Hay and Mohler, and Dunaliella tertiolecta Butcher were found to be capable of assimilating iodate at rates ranging from 0.003 to 0.24 nmol IO3−·μg chlorophyll a−1·h−1. The kinetics for the uptake of iodate can be modeled, and the similarity between the model and experimental results suggests that there is a steady state between iodate uptake and release of dissolved iodine from the cells, presumably in the form of iodide. Two experiments were conducted in the Sand Shoal Inlet of the Cobb Bay estuary (37°15′N, 75°50′W). The uptake of iodate was 0.26 and 0.08 nmol IO3−·μg chlorophyll a−1·h−1 during high and low tide, respectively. Using field estimates based on measured levels of iodate in the estuary, we estimate that phytoplankton can take up as much as 3% of the ambient pool of iodate on a daily basis and the entire pool in about 1 month. Thus, phytoplankton can be a significant component of the global iodine cycle by mediating changes in the speciation of iodine in the marine environment.
SHORT‐TERM RESPONSE OF THE DIADINOXANTHIN CYCLE AND FLUORESCENCE YIELD TO HIGH IRRADIANCE IN CHAETOCEROS MUELLERI (BACILLARIOPHYCEAE)1
Authors: Olaizola Miguel , Yamamoto Harry Y. 
Published: October 2004

ABSTRACTThe relationship between the diadinoxanthin cycle and changes in fluorescence yield in the diatom Chaetoceros muelleri Lemm. (clone CH10, Amorient Aquafarm, Inc., Hawaii) was investigated. High‐light‐induced changes in fluorescence yield and xanthophyll de‐epoxidation occurred very rapidly (first order rate constant 1.60 min−1). The observed light‐induced changes in diatoxanthin and diadinoxanthin concentration were consistent with a two‐pool scheme for diadinoxanthin, one of which does not undergo de‐epoxidation. Changes in xanthophyll concentration correlated with changes in in vivo absorbance indicating that diadinoxanthin cycle activity in vivo can be monitored spectrophotometrically. However, changes in cell absorbance were small relative to total optical absorption cross section. Increases in the concentration of diatoxanthin were linearly correlated with increases in the rate constant for thermal de‐excitation in the antenna of photosystem II (PSII). Antenna quenching produced or mediated by diatoxanthin may, thus, protect the PSII reaction center in diatoms. Changes in the maximum fluorescence yield suggested that changes in the reaction center also contributed to nonphotochemical quenching of fluorescence. Thus, reaction center quenching affected the relationship between antenna quenching and changes in photochemical efficiency producing the effect of a decrease in fluorescence yield without a decrease in photochemical efficiency.
PHOTOSYNTHETIC PROPERTIES OF PROTOPLASTS, AS COMPARED WITH THALLI, OF ULVA FASCIATA (CHLOROPHYTA)1
Authors: Beer Sven , Björk Mats 
Published: October 2004

ABSTRACTProtoplasts were prepared from Ulva fasciata Delile, and their photosynthetic performance was measured and compared with that of thalli discs. These protoplasts maintained maximal rates of photosynthesis as high as those of thalli (up to 300 μmol O2·mg chlorophyll−1·h−1) for several hours after preparation and were therefore considered suitable for kinetic studies of inorganic carbon utilization. The photosynthetic K1/2(inorganic carbon) at pH 6.1 was 3.8 μM and increased to 67, 158, and 1410 μM at the pH values 7.0, 7.9, and 8.9, respectively. Compared with these protoplasts, thalli had a much lower affinity for CO2 but approximately the same affinity for HCO3−. Comparisons between rates of photosynthesis and the spontaneous dehydration of HCO3− (at 50 μM inorganic carbon) revealed that photosynthesis of both protoplasts (which lacked apparent activity of extracellular/surface‐bound carbonic anhydrase) and thalli (which were only 25% inhibited by the external carbonic anhydrase inhibitor acetazolamide) could not be supported by CO2 formation in the medium at the higher pH values, indicating HCO3− uptake. Since both protoplasts and thalli were sensitive to 4,4′‐diisothiocyanostilbene‐2,2′‐disulfonate, we suggest that HCO3− transport was facilitated by the membrane‐located anion exchange protein recently reported to function in certain Ulva thalli. These findings suggest that the presence of a cell wall may constitute a diffusion barrier for CO2, but not for HCO3−, utilization under natural seawater conditions.
THE EVOLUTION OF PARASITISM IN RED ALGAE: CELLULAR INTERACTIONS OF ADELPHOPARASITES AND THEIR HOSTS1
Authors: Goff Lynda J. , Zuccarello Giuseppe 
Published: October 2004

ABSTRACTIn the initial stages of cell–cell interactions (spore germination and host penetration), the adelphoparasites Gardneriella tuberifera Kyl. and Gracilariophila oryzoides Setch. & Wilson form infection rhizoids that fuse directly with underlying host epidermal or cortical cells. In so doing, parasite nuclei and other organelles enter the cytoplasm of the host. The resulting heterokaryon may fuse with adjacent host cells either directly, via secondary pit connections, or by the dissolution or dislodgment of pit plugs from existing pit connections. The cell fusion events result in a heterokaryotic syncytium in which parasite nuclei replicate. In Gardneriella, formation of the syncytium induces surrounding host tissues to divide to form a photosynthetic callus. The internalized syncytium forms conjunctor and rhizoidal cells that fuse with host callus, eventually transforming the host callus into cells containing parasite nuclei. Gracilariophila does not induce surrounding host tissue to divide. Rather, division of the initial heterokaryotic tissue gives rise to the colorless mantle that protrudes from the host and forms reproductive structures. The heterokaryotic tissue also fuses with underlying host cells, thereby spreading parasite nuclei throughout adjacent host cells. In both these adelphoparasites, transformation of host cells by parasite nuclear invasion results in plastid dedifferentiation, an increase in mitochondria, autolysis of organelles, and accumulation of large amounts of floridean starch. The development and physiology of these parasites is similar to normal post‐fertilization processes in the hosts that give rise to carposporophytes and suggests that these adelphoparasites may have originated from perturbations of developmental pathways involved in their host's post‐fertilization development.
A MOLECULAR ANALYSIS OF ANALIPUS AND RALFSIA (PHAEOPHYCEAE) SUGGESTS THE ORDER ECTOCARPALES IS POLYPHYLETIC1
Authors: Tan Ian H. , Druehl Louis D. 
Published: October 2004

ABSTRACTWe report partial 18S ribosomal DNA sequences of Analipus japonicus (Harvey) Wynne and Ralfsia fungiformis (Grunnerus) Setchell et Gardner. These sequences were compared with the corresponding sequences of 13 brown algae representing six phaeophycean orders: Dictyotales, Ectocarpales, Fucales, Laminariales, Sphacelariales, and Syringodermatales. These 15 brown algae included 10 ectocarpoids representing nine ectocarpacean (sensu Gabrielson et al. 1989) families: Chordariaceae, Dictyosiphonaceae, Ectocarpaceae, Elachistaceae, Heterochordariaceae, Leathesiaceae, Punctariaceae, Ralfsiaceae, and Scytosiphonaceae. We addressed the controversial taxonomic placement of A. japonicus and R. fungiformis in the Ectocarpales by analysis of DNA sequences. Neighbor‐joining and maximum parsimony‐inferred phylogenies provided evidence that A. japonicus and R. fungiformis are not closely associated with the other representatives of the Ectocarpales. Bootstrap analyses suggest polyphyly of the order Ectocarpales (sensu Gabrielson et al.). However, our analysis failed to resolve the phylogenetic relationship between A. japonicus and R. fungiformis. Our results suggest that the ectocarpoids are just as distantly related to A. japonicus and R. fungiformis as they are to members of the advanced orders Desmarestiales, Dictyotales, Fucales, Laminariales, Sphacelariales, and Syringodermatales.
18S rDNA AND EVOLUTION IN THE DASYCLADALES (CHLOROPHYTA): MODERN LIVING FOSSILS1
Authors: Olsen Jeanine L. , Stam Wytze T. , Berger Sigrid , Menzel Diedrik 
Published: October 2004

ABSTRACTPhylogenetic relationships were inferred from parsimony and distance analyses of nuclear small‐subunit ribosomal DNA sequences taken from 14 species representing 8 of the 11 extant genera in the Dasycladales. Of 1733 aligned positions, 412 (23.8%) were variable and 251 (61%) of those were phylogenetically informative within the Dasycladales. Secondary structure was analyzed and taken into account during all phases of data analysis. Robustness of the trees was assessed using bootstrap analysis and g1statistics of tree‐length decay. Strongly supported branches were robust to all methods of analysis regardless of weighting schemes used. The secondary structure of the 18S within the Dasycladales agrees with that of other green algae with the exception of a shared deletion in stemloop E10‐1 (ca. 13 nucleotides long), which provides additional support for the uniqueness of this monophyletic group. A molecular clock was calibrated from the dasyclad fossil record and suggests a radiation of the Acetabulariaceae at 120 ± 30 million years (Ma) ago and the Dasycladaceae 215 ± 40 Ma ago. The split of the two lineages from a shared ancestor is estimated at 265 ± 50 Ma ago. Within the Dasycladaceae,NeomerisandCymopoliaare sister taxa, as areBatophoraandChlorocladus. Bornetellagroups with theNeomerisandCymopoliaclade in 78% of the bootstrap replicates. Relationships among the Acetabulariaceae show thatAcetabulariaandPolyphysado not form monophyletic groups as presently circumscribed. No evidence indicates thatAciculariais the oldest genus.Halicoryne, Chalmasia, andDasycladuswere not included in the analysis. Molecular data provide afresh background perspective from which to discuss the evolution of one of the most ancient lineages of green plants.
IDENTIFICATION OF GROUP‐ AND STRAIN‐SPECIFIC GENETIC MARKERS FOR GLOBALLY DISTRIBUTED ALEXANDRIUM (DINOPHYCEAE). I. RFLP ANALYSIS OF SSU rRNA GENES1
Authors: Scholin Christopher A. , Anderson Donald M. 
Published: October 2004

ABSTRACTTwo distinct small‐subunit ribosomal RNA genes (SSU rDNAs), termed the “A gene” and “B gene,” were recently found in the toxic dinoflagellate Alexandrium fundyense Balech. A restriction fragment length polymorphism (RFLP) assay was developed to rapidly detect the A and B genetic markers. SSU rDNA from 58 cultures with species designations of A. tamarense (Lebour) Balech, A. catenella (Whedon et Kofoid) Balech, A. fundyense, A. affine (Fukuyo et Inoue)Balech, A. minutum Halim, A. lusitanicum Balech, and A. andersoni Balech were screened. These cultures represent toxic and non‐toxic isolates from North America, western Europe, Thailand, Japan, Australia, and the ballast water of several cargo ships. The RFLP assay revealed five distinct groups. Three subdivided the A. tamarense/catenella/fundyense“species complex” into clusters defined by geographic origin, not by morphospecies designations. The fourth group consisted of A. affine, whereas the fifth group was represented by A. minutum, A. lusitanicum, and A. andersoni.The B gene was only found in A. tamarense, A. catenella, and A. fundyense, but not in all isolates. However, all North American isolates of this closely related group harbored this gene, and it also was found in some A. tamarense from scattered locations in Japan and in the ballast water of one ship that operated exclusively between Japan and Australia. Isolates without the B gene appeared to have only a single class of SSU rDNA. The B sequence was not essential for toxin production, but thus far those organisms harboring it were toxic. The A. tamarense/catenella/fundyense complex is composed of genetically distinct populations, within which may exist two or all three of the mophotypically defined species. The B gene is a promising taxonomic and biogeographic marker and may be useful for tracking the regional and/or global dispersal of particular populations.
NOTE. NEW EUENDOLITHIC CYANOBACTERIA FROM THE BAHAMA BANK AND THE ARABIAN GULF: HYELLA RACEMUS SP. NOV.1
Authors: Al‐Thukair Assad A. , Golubic Stjepko , Rosen Geoffroy 
Published: October 2004

ABSTRACTA new species of endolithic cyanobacteria, Hyella racemus sp. nov. (order Pleurocapsales), penetrates ooid grains in actively shoaling sands in shallow (0.5–5 m) waters of the Bahama carbonate platform and the Arabian Gulf. Hyella racemus is characterized by prolific branching, resulting in dense grape‐like cell clusters that penetrate the carbonate substrate. The clusters radiate inward and form deep, isodiametric pits. Resin casts of these pits are framboid (raspberry‐like) in shape. The borehole morphology conforms with the shape of the endolith body and can be identified in resin‐cast preparations. Cell division is by cleavage with regular alternation of division planes. The sheath is tight, layered, and colorless or yellow‐brown when under strong illumination. The new species is one of the most common endoliths in ooids of the Bahamas and the Arabian Gulf It differs from other members of this endolithic genus by its branching pattern and less prominent apical cells.
ENVIRONMENTAL FACTORS INFLUENCING DIATOM CELL MOTILITY1
Authors: Cohn Stanley A. , Disparti Nicholas C. 
Published: October 2004

ABSTRACTThis article describes the effect of various environmental conditions on the speed of freshwater diatoms. The diatoms display a wide distribution of cell speeds, from 0 to > 20 μm·s−l, as indicated by both the distribution of speeds within a cell population as well as the distribution of 1‐s interval speeds of individual cells. Cell length has little or no effect on cell speed, as the speed of large postconjugal populations ofCraticulaand smaller preconjugal cell populations were not significantly different. The diatoms showed a broad pH tolerance, withCraticula spp.andNitzschia spp.displaying active motility between pH 3 and 12 and pH 4 and 10, respectively, with velocity maxima for both species at approximately pH 7. In contrast to previous reports on marine diatoms, these freshwater diatoms do not require millimolar levels of external calcium for motility, as bothCraticula spp.andNitzschia spp.showed significant motility in distilled water (<0.5 μM calcium) for up to 5 h. Although addition of ≥500 μM of EGTA inhibited motility, this inhibition did not appear to be due to calcium chelation, as EGTA solutions preincubated with up to 20‐fold excess calcium, magnesium, or both still inhibited motility with the same dose‐dependent response as EGTA alone. Moreover, significant motility was restored by rinsing EGTA‐treated cells in distilled water, Ca‐free medium, or regular diatom medium. The calcium channel inhibitors lanthanum and ruthenium red also inhibited motility in a dose‐dependent manner, suggesting that regulation of internal calcium stores may be important in motility.Craticulamotility also declines rapidly in medium ≥50 mOsM while the isotonic concentration appears to be 100–120 mOsM, suggesting that movement may require the plasma membrane to be exerting a force ≥50–70 mOsM osmotic pressure (1–1.5 atm) against the cell wall.
EFFECT OF TEMPERATURE AND IRRADIANCE ON GROWTH OF HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE)1
Authors: Fan Lu , Vonshak Avigad , Boussiba Sammy 
Published: October 2004

ABSTRACTThe growth characteristics of Haematococcus pluvialis Flotow were determined in batch culture. Optimal temperature for growth of the alga was between 25° and 28°C, at which the specific growth rate was 0.054 h−1. At higher temperatures, no cell division was observed, and cell diameter increased from 5 to 25 μm. The saturated irradiance for growth of the alga was 90 μmol quanta · m−2·s−1; under higher irradiances (e.g. 400 μmol quanta·m−2·s−1) astaxanthin accumulation was induced. Growth rate, cell cycle, and astaxanthin accumulation were significantly affected by growth conditions. Careful attention should be given to the use of optimal growth conditions when studying these processes.
VARIABILITY OF PHOTOSYSTEM II QUANTUM YIELD AND RELATED PROCESSES IN CHLORELLA PYRENOIDOSA (CHLOROPHYTA) ACCLIMATED TO AN OSCILLATING LIGHT REGIME SIMULATING A MIXED PHOTIC ZONE1
Authors: Kroon Bernd M. A. 
Published: October 2004

ABSTRACTThe regulation of photosystem II (PSII)‐related parameters was characterized for Chlorella pyrenoidosa Chick grown in continuous nutrient‐replete culture and acclimated to a light field simulating fluctuations of a natural environment. The maximum quantum yield for charge separation at PSII showed a light‐driven decrease during the first half of the photoperiod when incident irradiance (integrated hourly) was increasing to a midday maximum, This change was accompanied by a decrease in the effective cross‐section for all PSIIs and the connectivity between PSIIs, while the cross‐section for inactive centers increased. Furthermore, a decrease in the number of active PSII centers and the amount of QB bound to D1 became evident. During the second half of the day, as irradiance declined toward the end of the photoperiod, all the observed changes in PSII photochemistry were reversed. The low quantum yield values at the middle of the photoperiod returned to 85% of the value at the end of the photoperiod by the addition of far‐red light, suggesting that a State I–II–I transition took place during the day. Measured rates of oxygen production correlated well with fluorescence‐derived estimates of photosynthesis. The overall results suggest that PSII photochemistry is optimized to minimize the susceptibility to photoinhibition and to allow balanced growth under fluctuating irradiation and that the impact of these alterations on primary production can be adequately monitored through bio‐optical measurements alone.
TAXONOMY AND ULTRASTRUCTURE OFGOMPHONEIS MESTASP. NOV. (BACILLARIOPHYTA), A NEW EPILITHIC DIATOM FROM THE MESTA RIVER, BULGARIA1
Authors: Passy‐Tolar Sophia I. , Lowe Rex L. 
Published: October 2004

ABSTRACTA new species from the diatom genusGomphoneis, G. mesta, was described following morphological and ultra‐structural analyses of its frustules by light and scanning electron microscopy. The valve striation consisting of double rows of areolae and the presence of longitudinal lines dictate the systematic position of this taxon in the genusGomphoneis.The set of features that distinguishesG.mesta from allied taxa is small valves, 26.5–81.6 μm in length and 7–12.5 μm in width, lanceolate to clavate shape, with a broadly lanceolate axial area, and longitudinal lines positioned next to the valve margins, thus contributing to a general thickening of the valve outline. When compared to other members of the genus,G. mestamost resemblesG. magnaKociolek & Stoermer.Gomphoneis mestadominates the epilithic community, growing in the Cherna Mesta, a pristine high‐mountainous tributary of the Mesta River in Bulgaria. The species has been also found as small populations in all other benthic habitats of the Cherna Mesta and in a few locations along the Mesta River.
A LOW‐VOLUME FLOW TANK FOR MEASURING NUTRIENT UPTAKE BY LARGE MACROPHYTES1
Authors: Hurd Catriona L. , Quick Michael , Stevens Craig L. , Laval Bernard E. , Harrison Paul J. , Druehl Louis D. 
Published: October 2004

ABSTRACTA recirculating flow‐tank was designed and tested to measure inorganic nutrient uptake by, and visualize the movement of seawater around, large macrophytes. The tank volume was small (46 L), and a propeller drive produced unidirectional mean flow. A turbulence reduction section dampened turbulence in the test section to a low level, so that water movement within this region was virtually laminar. The test section of the tank was wider than that of previous designs, allowing whole blades of Macrocystis integrifolia Bory and juvenile plants of Nereocystis luetkeana (Mert.) Post, et Rupr. to be placed in the flow, away from the influence of velocity boundary layers associated with the tank walls. The tank's use in macroalgae nutrient uptake and flow visualization experiments was demonstrated.
EVOLUTION OF THE ANTARCTIC MARINE BENTHIC ALGAL FLORA
Authors: Clayton Margaret N. 
Published: October 2004

ABSTRACTThere are many logistic difficulties associated with studying Antarctic marine algae and, as a consequence, the taxonomic information available is far from comprehensive and any generalizations should be regarded with caution. The Antarctic marine benthic flora is characterized by a low species richness. Biogeographical characteristics of the flora are outlined. There is a high degree of endemism, possibly around 35–40%. Other major floristic elements are a group of species with a distribution extending to Tierra del Fuego and subantarctic islands, a group spread through temperate regions of the Southern Hemisphere, and a cosmopolitan group. Ecological observations show that ice has a major effect on the occurrence and distribution of algae, and ecophysiological studies indicate that Antarctic macroalgae possess various adaptations to ice, low temperatures, and strongly seasonal light conditions. Possible trends in the evolution of the Antarctic benthic marine flora, including a reduction in species richness and the origins of biogeographical links with subantarctic and temperate regions of the Southern Hemisphere, are discussed in the context of tectonic and climatic changes over the past 100 million years. A comparison is made with studies on the evolution of shallow‐water marine fauna.