bluuebunny/crossref_metadata_2025_split huggingface dataset:
VARIATION IN NITROGEN PHYSIOLOGY AND GROWTH AMONG GEOGRAPHICALLY ISOLATED POPULATIONS OF THE GIANT KELP,MACROCYSTIS PYRIFERA(PHAEOPHYTA)1
Authors: Kopczak Charles D. , Zimmerman Richard C. , Kremer James N. 
Published: October 2004

ABSTRACTThree geographically isolated populations of the giant kelp,Macrocystis pyrifera(L.) C. Ag., were examined for responses to nitrate availability in batch culture experiments using juvenile sporophytes reared from spores in the laboratory. Although maximum rates of nitrate‐saturated growth were similar among groups, there were significant quantitative differences in the response to nitrate limitation that can be related to natural patterns of nutrient availability at these sites. Plants from Santa Catalina Island (most oligotrophic) achieved maximum growth rates at ambient nitrate concentrations that were lower than those for plants from Monterey Bay, California (most eutrophic), or Refugio State Beach (near Santa Barbara, California). Tissue nitrogen and amino acid concentrations were highest in plants cultured from Santa Catalina Island populations at all external nitrate concentrations, suggesting that differences in nitrate requirements for growth may reflect the efficiency of nitrate uptake and assimilation at subsaturating nitrate concentrations. Given the different physical environments from which these plants came, the data suggest that geographically isolated populations ofM. pyriferahave undergone genetic divergence that can be explained by ecotypic adaptation to unique habitat conditions at these sites.
NITROGENASE CONFINED TO RANDOMLY DISTRIBUTED TRICHOMES IN THE MARINE CYANOBACTERIUM TRICHODESMIUM THIEBAUTII1
Authors: Bergman Birgitta , Carpenter Edward J. 
Published: October 2004

ABSTRACTNitrogenase reductase (Fe‐protein) was detected in the marine planktonic cyanobacterium Trichodesmium. The molecular weight was about 38 kD, as shown by western blotting using anti ‐Rhodospirillum rubrum nitrogenase reductase antiserum. The enzyme was confined to a limited number (ca. 10–40%) of randomly distributed trichomes in the Trichodesmium colonies, as shown by immunogold localization and transmission electron microscopy. Associated microorganisms had little or no nitrogenase. Nitrogenase showed a diel cycle in localization: present throughout the cytoplasm of cells in N2‐fixing (daytime) colonies but at the periphery of non‐N2‐fixing (nighttime) colonies. This structural arrangement of N2‐fixing trichomes and nitrogenase is novel and different from the previously held paradigm for this and other diazotrophic cyanobacteria.
RESPONSE OF MARINE SYNECHOCOCCUS (CYANOPHYCEAE) CULTURES TO IRON NUTRITION1
Authors: Rueter John G. , Unsworth Nancy L. 
Published: October 2004

ABSTRACTThree clones of marine Synechococcus (WH6501, WH7803, and WH8018) were grown through at least three transfers, at 6‐day intervals, in synthetic medium with total iron concentrations from 10−9 to 10−6 M. After 6 days of exponential growth, these cultures were harvested, and the cell density and protein and pigment concentrations were measured. Aliquots of the culture were assayed for their carbon fixation rates at two light intensities. Cell density and protein concentration increased by up to 7.8 times over a range of iron from the lowest (10−9 M) to the highest concentrations (10−6 M). The concentration of chlorophyll‐a and phycobiliproteins showed a wider range of response, increasing by up to 48 times. The carbon fixation rate (per mL of culture) also increased approximately 40 times over the total range of iron concentration. The ranges of these biochemical and physiological responses were much lower than the range of total available iron, which was 1000‐fold, and the range of total cellular iron, which was estimated to be about 160‐fold. This “less‐than‐linear” relationship indicates that the cells are adapting to make more efficient use of iron under limiting conditions. Our results demonstrate characteristics of iron‐limited Synechococcus that may be important in understanding the relationships between primary productivity and iron availability in the oceans.
IMMUNOFLUORESCENCE MICROSCOPY OF FERTILIZATION AND PARTHENOGENESIS IN LAMINARIA ANGUSTATA (PHAEOPHYTA)1
Authors: Motomura Taizo 
Published: October 2004

ABSTRACTNormal fertilization and parthenogenesis of unfertilized eggs were observed in Laminaria angustata Kjellman by indirect immunofluorescence microscopy using a tubulin antibody. Sperm aster formation did not occur at plasmogamy. The centrosome of the egg gradually disappeared. Shortly after karyogamy, one centrosome reappeared near the zygote nucleus. During mitosis, the centrosome replicated and the daughter centrosomes migrated to opposite poles. The mitotic spindle was formed by microtubules that elongated from both poles. After the first cell division, each of the daughter cells received one centrosome that persisted throughout the development of the sporophyte. During parthenogenetic development, abnormal mono‐, tri‐, and multi‐polar spindles were formed. These abnormal spindles caused abnormal nuclear and cytoplasmic division. Thus, cells were produced with 1) no nuclei, 2) multiple nuclei, 3) irregular numbers of chromosomes, and/or 4) no centrosomes. This is one of the reasons for the abortion and abnormal morphogenesis during parthenogenesis. Ultrastructural observations showed that, although cells of some parthogenetic sporophytes have centrioles, cells of almost all abnormally shaped parthenogenetic sporophytes lack centrioles. These results suggest that centrioles are required for normal centrosomal functions in Laminaria. Although centrioles are inherited paternally, some centrosomal material appears to be present or produced de novo in unfertilized eggs.
KARYOLOGY OF BANGIA ATROPURPUREA (RHODOPHYTA, BANGIALES) FROM MEDITERRANEAN AND NORTHEASTERN ATLANTIC POPULATIONS1
Authors: Gargiulo Gaetano M. , De Masi Flora , Tripodi Giacomo 
Published: October 2004

ABSTRACTWe studied the karyology of Bangia atropurpurea (Roth) C. Ag. collected from marine and freshwater populations from the Mediterranean region and some northeastern Atlantic localities. Gametophytic thalli had two haploid karyotypes, n = 3 and n = 4. The n = 4 karyotype was only occasionally present in the Mediterranean and was also found in one Atlantic population, confirming a previous report. We propose that the four‐chromosome karyotype is an aneuploid form, n + 1. Chromosomes were frequently observed either in a parallel arrangement or in a circular configuration.
REGENERATION AND SEXUAL DIFFERENTIATION OF GRIFFITHSIA JAPONICA (CERAMIACEAE, RHODOPHYTA) THROUGH SOMATIC CELL FUSION1
Authors: Hwang Mi Sook , Kim Hyung‐Seop , Lee In Kyu 
Published: October 2004

ABSTRACTHybrid cells were obtained from somatic cell fusion among male, female, and tetrasporangial plants in Griffithsia japonica Okamura by a wound‐healing process. Isolated fusion cells regenerated new mature plants with mixed reproductive structures. The plants regenerated from hybrid cells between male and female plants developed into 1) spermatangiate, 2) carpogonial, 3) bisexual with spermatangia and carpogonial branches, 4) mixed‐phase with spermatangia and tetrasporangia, or 5) bisexual/mixed‐phase plants with spermatangia, carpogonial branches, and tetrasporangia. About 70% of the plants regenerated from hybrid cells between male and female plants produced tetrasporangia that were always formed with spermatangia on a single cell. Some of those tetrasporangia released tetraspores, six of which gave rise to mature plants. The plants regenerated from hybrid cells between male and tetrasporangial plants developed into spermatangiate, tetrasporangiate, or mixed‐phase plants with spermatangia and tetrasporangia. The plants regenerated from hybrid cells between female and tetrasporangial plants developed into carpogonial, tetrasporangiate, or mixed‐phase plants with carpogonial branches and tetrasporangia. All types of reproductive structures we re functional.
INFLUENCE OF CELL VOLUME ON THE GROWTH AND SIZE REDUCTION OF MARINE AND ESTUARINE DIATOMS1
Authors: Mizuno Makoto 
Published: October 2004

ABSTRACTThe maximal growth rate (μmax) of 19 marine and estuarine diatoms decreased with increasing cell volume (V). The relationship between log μmax(Y) and log V (X) was calculated. Statistical analyses showed that the slope of the equation was not significantly different from those obtained by other researchers and that the 95% confidence intervals of mean μmaxat cell volumes of 103–105μm3were not significantly different from those cited in most studies. A new regression line for diatoms was calculated as follows: log μmax= 0.47–0.14 log V; r =–0.69.The rate of size reduction per generation of the 19 diatom species ranged from 0.03 to 0.87 μm per generation. The rate increased with increasing cell length and cell volume and with decreasing maximum division rate. Statistical analyses showed that the rate was closely related to the cell volume and to the reciprocal of the growth rate. The relationships between maximal growth rate and cell volume and between rate of size reduction and cell volume showed that a diatom with a large volume had a smaller maximal growth rate and a larger rate of size reduction than a diatom with a small volume. The estimates using the equation for the regression line between the rate of size reduction and the reciprocal of maximum division rate indicated that a diatom with a high maximum division rate would need more generation equivalents for a certain size reduction than a diatom with a low maximum division rate, but the periods required for reduction would be approximately equal irrespective of maximum division rate.
ANTINEOPLASTIC ACTIVITY OF CULTURED BLUE‐GREEN ALGAE (CYANOPHYTA)1
Authors: Patterson Gregory M. L. , Baldwin Cynthia L. , Bolis Christine M. , Caplan Faith R. , Karuso Helen , Larsen Linda K. , Levine Ira A. , Moore Richard E. , Nelson Carrie S. , Tschappat Kathryn D. , Tuang Grace D. , Furusawa Eiichi , Furusawa Shinobu , Norton Ted R. , Raybourne Richard B. 
Published: October 2004

ABSTRACTA large‐scale screening program was initiated to evaluate laboratory‐cultured blue‐green algae (cyanobacteria) as a source of novel antineoplastic agents. Approximately 1000 cyanophyte strains from diverse habitats were cultured to provide extracts for testing. The screening program identified the families Scytonemataceae and Stigonemataceae as prolific producers of novel cytotoxic compounds. Rates of rediscovery of known compounds were relatively low.
cAMP AND cAMP‐STIMULATED PROTEIN PHOSPHORYLATION IN ZOOSPORES OF BROWN ALGAE1
Authors: Ohmori Masayuki , Muto Shoshi , Miyachi Shigetoh 
Published: October 2004

ABSTRACTAdenosine 3′,5′‐cyclic monophosphate (cAMP) and guanosine 3′,5′‐cyclic monophosphate (cGMP) were detected at concentrations of 8–11 and 10–20 pmol · mg−1 protein, respectively, in zoospores of a brown alga, Undaria pinnatifida (Harvey) Suringer. Cellular levels of these cyclic nucleotides did not substantially change during dark to light transition. cAMP‐stimulated protein phosphorylation was found in soluble cell‐free extracts of zoospores of Undaria pinnatifida and Laminaria angustata Kjellman.
STEROLS OF CEPHALEUROS (TRENTEPOHLIACEAE), A PARASITIC GREEN ALGA1
Authors: Patterson Glenn W. , VanValkenburg Shirley D. 
Published: October 2004

ABSTRACT24‐Ethylcholesterol, 24‐ethylcholesta‐5,7,22‐trienol, dihydrolanosterol, 24‐ethylcholesta‐7,22‐dienol, and 4‐methyl‐24‐ethylcholesta‐7,22‐dienol were identified in cultured Cephaleuros in small quantities. Cholesterol made up 19% of the total sterol. The principal sterol, making up 65% of the total sterol, was 4,24‐dimethylcholest‐7‐enol, a new algal sterol. This is the first report of this sterol as the principal sterol of any living organism.
A NOVEL TECHNIQUE FOR PREPARATION OF AXENIC CULTURES OF SYMBIODINIUM (PYRROPHYTA) THROUGH SELECTIVE DIGESTION BY AMOEBAE1
Authors: Polne‐Fuller Miriam 
Published: October 2004

ABSTRACTThe marine amoeba Trichosphaerium Am‐I‐7 was used as a tool for preparing unialgal axenic cultures of nondigestible Symbiodinium and Porphyridium species. The resistance of these unicellular algae to the amoebal digestive enzymes, and the differential digestion of bacteria, protozoans, and other algae, resulted in cleansed cells of Symbiodinium and Porphyridium that remained in the amoebal food vacuoles. During multiple fission, the amoeba evacuated its food vacuoles and released the trapped and intact algae, which were then successfully cultured. This method of cleaning was especially useful with algal species that were sensitive to antibiotics or other germicidal agents.
PHAGOTROPHY IN THE FRESHWATER, PHOTOSYNTHETIC DINOFLAGELLATE AMPHIDINIUM CRYOPHILUM1
Authors: Wilcox Lee W. , Wedemayer Gary J. 
Published: October 2004

ABSTRACTThe cold‐water, photosynthetic dinoflagellate Amphidinium cryophilum Wedemayer, Wilcox & Graham feeds phagotrophically on other dinoflagellate species. Food is ingested through a feeding tube, termed here the “phagopod,” which extends from the antapex. The peduncle of this organism plays no observable role in the feeding process. The phagopod is essentially a hollow cylinder composed electron‐opaque material that is possibly deposited on a membrane. No Amphidinium cytoplasmic components, including microtubules or other cytoskeletal elements, were observed in the phagopod. Prefeeding cells aggregate, in small clumps near prey organisms with their phagopods extended. Eventually some cells commence feeding, first inserting the phagopod through the prey cell‐covering and then slowly, over a period of 10 min or more, drawing cytoplasm through the phagopod and into a nascent food vacuole. Both light and electron microscopy suggest that one or more prey cell amphiesmal membranes remain intact during the feeding process. Upon completion of feeding, the Amphidinium cell swims off with a prominent food vacuole in the hypocone, leaving at least part of the phagopod attached to the prey cell. Phagotrophy in A. cryophilum seems to vary with light intensity. At low light intensities, cells feed phagotrophically and are nearly colorless, whereas at high light levels they feed much less frequently, if at all, and are brightly pigmented.
INTRON REVEALED BY NUCLEOTIDE SEQUENCE OF LARGE SUBUNIT OF RIBULOSE‐1,5‐BISPHOSPHATE CARBOXYLASE/OXYGENASE FROM CODIUM FRAGILE (CHLOROPHYTA): PHYLOGENETIC ANALYSIS1
Authors: Manhart James R. , VonderHaar Raymond A. 
Published: October 2004

ABSTRACTThe coding sequence for the large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (rbcL) from Codium fragile (Suringar) Hariot chloroplast DNA is 1428 bp in length and contains a 1813‐bp group II intron. The only other organisms in which introns have been found in the rbcL gene are Euglena and Astasia. The Codium intron likely had a separate origin from the Euglena and Astasia introns, based on comparisons of intron sizes and sequences. Phylogenetic analyses of rbcL nucleotide and amino acid sequences place Codium between Chlorella and two Chlamydomonas spp., indicating that the Chlorophyceae may be polyphyletic.
EVOLUTIONARY RELATIONSHIPS BETWEEN FOUR SPECIES OF CLADOPHORA (CLADOPHORALES, CHLOROPHYTA) BASED ON DNA–DNA HYBRIDIZATION1
Authors: Bot Peter V. M. , Brussaard Corina P. D. , Stam Wytze T. , van den Hoek Chris 
Published: October 2004

ABSTRACTAnalysis of the reassociation kinetics of the DNA from Cladophora pellucida (Huds.) Kütz. indicates that the genome of this benthic alga is comprised of approximately 75% repetitive sequences. Single‐copy sequences reassociated with a rate constant of 1.8 × 10−3 M−1· s−1, which corresponds to a haploid genome size of 4.7 × 108 bp. Genotypic relationships between members of the form section Longiarticulatae were determined by the method of DNA–DNA hybridization. No significant divergence was observed between the single‐copy sequences of C. pellucida isolates from the East Atlantic coast and Mediterranean Sea. Cladophora feredayi Harv. and C. att. ad pellucida from Australia and C. pellucidoidea van den Hoek from the West Atlantic coast were highly and about equally divergent from C. pellucida. The data support the hypothesis that the West Atlantic–West Pacific divergence reflects the middle Miocene closure of the Mediterranean–Indo‐Pacific seaways, and the hypothesis that the Northwest Atlantic–Northeast Atlantic divergence reflects the middle Miocene thermal separation of these coasts.
RESTRICTION ENDONUCLEASE ANALYSIS OF RIBOSOMAL DNA SEQUENCE VARIATION IN LAMINARIA (PHAEOPHYTA)1
Authors: Bhattacharya Debashish , Mayes Charlene , Druehl Louis D. 
Published: October 2004

ABSTRACTThe taxonomy and evolutionary relationships of species in the genus Laminaria are poorly understood. Previous studies have demonstrated significant plasticity of morphological characters used to describe taxa, and interfertility has been reported among putative species. We analyzed nuclear ribosomal DNA (rDNA) sequence variation in eight species of Laminaria (L. agardhii Kjell., L. digitata (Huds.) Lamour., L. groenlandica Rosenv. [sensu Druehl 1968], L. longicruris De la Pyl., L. longipes Bory, L. saccharina (L.) Lamour., L. setchellii Silva, and L. yezoensis Miyabe) to elucidate evolutionary relationships in this genus. Restriction maps were constructed using a small subunit rDNA probe from Costaria costata (Turn.) Saunders, an rDNA repeat from the nematode Caenorhabditis elegans, and 11 hexameric restriction endonucleases in an annealing analysis of genomic DNA. Laminaria rDNA restriction maps were compared to each other and to that of the outgroup taxon, C. costata. rDNA restriction maps of Laminaria species and C. costata were similar. Restriction fragment length polymorphisms mapped to both the coding regions and the nontranscribed spacer of rDNA. Laminaria species were distinguished with this method. The restriction maps of L. agardhii, L. saccharina, and L. longicruris were identical, supporting a previous hypothesis that these species are conspecific. Comparison of restriction maps of Laminaria species suggested that the generic subdivision of Sections Simplices and Digitatae may be invalid.
INORGANIC CARBON LIMITATION OF PHOTOSYNTHESIS IN ULVA ROTUNDATA (CHLOROPHYTA)1
Authors: Levavassur Guy , Edwards Gerald E. , Osmond C. Barry , Ramus Joseph 
Published: October 2004

ABSTRACTA computerized oxygen electrode Astern was used to make rapid and accurate measurements of photosynthetic light and dissolved inorganic carbon (DIC) response cures with a macroalga. Ulva rotundata Blid. was grown in an outdoor, continuous flow system in seawater under sunlight or 9% of sunlight at Beaufort, North Carolina. The light compensation points in the shade‐ and sun‐grown plants, measured in seawater, were at photon flux densities (PFDs) of 16 and 27 μmol. Photons·m−2·s−1, respectively but the quantum yield of O2 evolution was not significantly different. Rates of photosynthesis in seawater per unit area of thallus under saturating light and rates of dark respiration were about 1.5‐fold higher in sun‐ than in shade‐grown plants. The concentration of DIC in seawater (approximately 2 mM) limited photosynthesis at absorbed PFDs above 60–70 μmol photons·m−2·s−1 Addition of 20 mM inorganic carbon had no effect on quantum yield but caused about a 1.5‐fold increase in the light‐saturated photosynthetic rate in both shade‐ and sun‐grown Ulva. The effect of DIC supplementation was greatest in plants grown in October and least in plants grown in June. The light‐ and DIC‐saturated rate of photosynthesis in seawater was similar to the maximum rate obtained by exposing Ulva to 10% CO2, in the gas phase. The carbon isotope values (δ13C, reflecting the 13C/12C ratio compared to a standard) of Ulva grown in the same seawater supply were dependent on light and agitation. Samples from Beaufort Inlet were more negative (δ13C value, −20.03‰) than those grown in bright light with agitation (δ13C value, −17.78‰ outdoors; −17.23‰ indoors), which may indicate DIC supply limited carbon uptake in seawater.
NITROGENASE ACTIVITY, PHOTOSYNTHESIS, AND THE DEGREE OF HETEROCYST AGGREGATION IN THE CYANOBACTERIUM ANABAENA FLOS‐AQUAE1
Authors: Kangatharalingam N. , Dodds Walter K. , Priscu John C. , Paerl Hans W. 
Published: October 2004

ABSTRACTThe nitrogen‐fixing cyanobacterium Anabaena flosaquae Lyngb.) De Breb. exhibited aggregation of heterocysts from different filaments in a eutrophic lake and when grown in unialgal culture. The resulting aggregated filaments formed unialgal flocculent masses having a thickness of several centimeters that apparently resulted from cohesive mucilage surrounding heterocysts. We tested the effects of heterocyst aggregation on nitrogenase activity (NA) and photosynthesis in relation to microscale environmental O2 gradients. The redox indicator 2,3,5‐triphenyl tetrazolium chloride showed that aggregated heterocysts had lower intracellular redox potential than those that were dispersed. Microelectrode measurements showed that heterocyst aggregates in actively photosynthesizing flocculent masses were surrounded by a microzone of O2 30% higher than in the surrounding water: dispersed cells exhibited no such elevated O2 microzone. Despite high levels of O2, NA was greater in aggregated than dispersed samples, Microscale irradiance measurements made with a fiber optic light probe showed that 40% of the incident light was absorbed within the first 3 mm of a 1‐cm‐thick flocculent mass. The microscale irradiance data, together with nitrogenase and photosynthesis versus irradiance data, imply that the ratio of N:C fixation is lowest in filaments on the outside of 1.5–2.0‐cm masses and increases toward the center.
FEEDING APPARATUS OF THE COLORLESS FLAGELLATE KATABLEPHARIS (CRYPTOPHYCEAE)1
Authors: Lee Robert Edward , Kugrens Paul , Mylnikov Alexander Petrovich 
Published: October 2004

ABSTRACTThe feeding apparatus of Kalablepharis ovalis (isolated from a freshwater impoundment in Colorado) and Katablepharis clone G‐2 (isolated from the littoral of the Black Sea near Yalta in the Crimea) consists of inner and outer oval‐shaped arrays of microtubules that begin at the anterior end of the cell and pass into the posterior of the cell. Each array of microtubules contains groups of microtubules with two to eight microtubules per group depending on the position of the array in the cell. A specialized area of the plasma membrane, the mouth, occurs at the anterior end of the cell. The mouth is oval with the long axis oriented dorsoventrally and consists of a raised ridge surrounding a central depression. The anterior end of the microtubules of the inner and outer arrays supports the raised ridge of the mouth. In freeze‐fracture replicas, the protoplasmic face of the plasma membrane contains intramembrane particles on the raised ridge of the mouth. Three small membrane‐cisternae occur on the protoplasmic side of the plasma membrane in the area of the mouth. Katablepharis clone G‐2 also has five or six additional large membrane‐cisternae associated with the inner microtubular array in the anterior portion of the cell. These larger membrane‐cisternae do not occur in K. ovalis. Vesicles with electron‐dense contents occur in association with the microtubular arrays. Katablepharis ovalis has a second type of vesicle containing a single‐membrane profile associated with the microtubule arrays. The structure of the microtubular arrays in Katablepharis is compared with similar structures in suctorian ciliates and dinoflagellates.