bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHOTOSYNTHETIC PIGMENTS OF PSEUDOSCOURFIELDIA MARINA AND SELECT GREEN FLAGELLATES AND COCCOID ULTRAPHYTOPLANKTON: IMPLICATIONS FOR THE SYSTEMATICS OF THE MICROMONADOPHYCEAE (CHLOROPHYTA)1
Authors: Fawley Marvin W. 
Published: October 2004

ABSTRACTPhotosynthetic pigments of the green flagellate Pseudoscourfieldia marina (Throndsen) Manton (Micromonadophyceae) are similar to those of the coccoid Pycnococcus provasolii Guillard; prasinoxanthin is the predominant carotenoid. Other organisms that possess prasinoxanthin also possess additional pigments not found in either P. marina or P. provasolii. Uriolide, a xanthophyll previously described from the coccoid done URI 266G, was also found in Mantoniella squamata (Manton et Parke) Desikachary, Micromonas pusilla Manton et Parke and Mamiella gilva (Parks et Rayns) Moestrup, all flagellate members of the Mamiellales, and the coccoid clone IV E5G. Other unidentified carotenoids were also present in M. squamata, M. pusilla, and M. gilva. These results suggest that P. marina and the coccoid organisms URI 266G and IV E5G may be related to the Mamiellales, and that P. provasolii may be more closely related to P. marina than to M. squamata, M. pusilla, and M. gilva.
FATTY ACID CONTENT AND CHEMICAL COMPOSITION OF FRESHWATER MICROALGAE1
Authors: Ahlgren Gunnel , Gustafsson Inga‐Britt , Boberg Merike 
Published: October 2004

ABSTRACTFatty acid (FA), total lipid, protein, amino acid, carbon, nitrogen, and phosphorus content was analyzed in 24 samples of freshwater microalgae. The samples originated from batch, continuous, or mass cultures in various growth phases and from net samples from lakewater. FA were analyzed quantitatively by using an internal standard in a GLC system and expressed as mg·g−1 dry weight (DW). The FA of one group of blue‐greens (e.g. Oscillatoria and Microcystis) were similar to those of the greens with higher amounts of 18C acids of the ω3 type compared to the ω6 type, whereas the other group (e.g. Anabaena and Spirulina) contained mostly ω6 acids. The flagellates, a taxonomically diverse group, were characterized by high amounts of long‐chained (20–22 C) polyunsaturated FA (PUFA), particularly of the ω3 type. The ω3/ω6 ratio appears to be highest in algae in the exponential growth phase. The increased lipid content in stressed algae was mostly due to increased saturated fatty acids and ω6 acids, whereas the valuable ω3 acids were unchanged or even decreased.Amino acid composition (% of total amino acids) did not vary much betaken species, but when analyzed quantitatively (mg‐g−1 DW), varied considerably between species and within species in different growth phases. The nitrogen and phosphorus contents were variable in all three algal groups. The relationship between PUFA and phosphorus content differed among the algal groups. The data suggest that PUFA in the phospholipids consist mostly ω3 acids.
AMPHIESMAL ULTRASTRUCTURE OF DINOFLAGELLATES: A REEVALUATION OF PELLICLE FORMATION1
Authors: Höhfeld Ingo , Melkonian Michael 
Published: October 2004

ABSTRACTThe ultrastructure of the amphiesma during pellicle formation was investigated in two species of Dinophyceae,Amphidinium rhynchocephalumAnissimowa andHeterocapsa niei(Loeblich) Morrill & Loeblich using thin sections. In both species the amphiesma consists of an outermost membrane (i.e. the plasma membrane) underlain by amphiesmal vesicles. InA. rhynchocephalumthe latter appear empty whereas each amphiesmal vesicle inH. nieicontains a thecal plate and a thin, amorphous layer (dark‐staining layer) located between, the thecal plate and the inner amphiesmal vesicle membrane. When cells of both taxa are carefully fixed, amphiesmal vesicles are always separate entities (i.e. the sutures are undisrupted). During ecdysis the following amphiesmal components are shed: the plasma membrane, the outer amphiesmal vesicle membrane, and inH. nieithe thecal plates. The inner membranes of the amphiesmal vesicles then fuse with each other and form a continuous membrane (termed pellicle membrane) that remains tightly oppressed to an underlying amorphous layer (pellicular layer). InA. rhynchocephalumthe pellicular layer is already present in vegetative non‐ecdysed cells, whereas inH. nieiit forms during ecdysis beneath the pellicle membrane. During ecdysis inH. niei, material from the dark‐staining layer precipitates on the outer surface of the pellicle membrane, where it forms a characteristic honeycomb pattern. The new observations are incorporated into a revised model of pellicle formation in dinoflagellates and contrasted with earlier proposals.
A MOLECULAR AND MORPHOLOGICAL ANALYSIS OF THE GYMNOGONGRUS DEVONIENSIS (RHODOPHYTA) COMPLEX IN THE NORTH ATLANTIC1
Authors: Maggs Christine A. , Douglas Susan E. , Fenety John , Bird Carolyn J. 
Published: October 2004

ABSTRACTThe Gymnogongrus devoniensis (Greville) Schotter complex in the North Atlantic Ocean was elucidated by comparative molecular, morphological, and culture studies. Restriction fragment length patterns and hybridization data on organellar DNA revealed two distinct taxa in samples from Europe and eastern Canada. Nucleotide sequences for the intergenic spacer between the large and small subunit genes of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco), and the adjoining regions of both genes, differed by 12.5–13.4% between the two taxa. One of the taxa, which included material from the type locality of G. devoniensis at Torbay, Devon, England, was taken to represent authentic G. devoniensis. Within this taxon, samples from Ireland, England, northern France, northern Spain, and southern Portugal showed great morphological variation, particularly in habit, but their Rubisco spacer sequences were identical or differed by only a single nucleotide. Constant morphological features included the development, from a single auxiliary cell, of the spherical cystocarp with a thick mucilage sheath that appears to be typical of Gymnogongrus species with internal cystocarps. Two life‐history types were found. Northern isolates underwent a direct‐type life history, recycling apomictic females by carpospores, whereas the Portuguese isolate followed a heteromorphic life history in which carpospores gave rise to a crustose tetrasporophyte.The second group of samples, from Nova Scotia and Northern Ireland, provisionally referred to as Gymnogongrus sp., showed little morphological variation. The life history in both areas consists of apomictically reproducing diploid female gametophytes and diploid crustose bisporophytes and tetrasporophytes. Rubisco spacer sequences of the samples were identical, and the plasmid previously described in the Nova Scotian samples was also present in the Northern Ireland population. This species is widely distributed in the western Atlantic, from Newfoundland to Massachusetts. In Europe, gametophytes are known only at one site, but crusts are distributed from Denmark, Scotland (and probably Norway) to France. It is very likely that this species was introduced from one side of the North Atlantic to the other by shipping during the early nineteenth century. Several morphological features are unusual within the genus but are shared with G. leptophyllus J. Agardh from the eastern Pacific Ocean, and further work is necessary to determine whether Gymnogongrus sp. and G. leptophyllus are conspecific.
DISTRIBUTION AND SYSTEMATICS OFBATRACHOSPERMUM(BATRACHOSPERMALES, RHODOPHYTA) IN NORTH AMERICA. 1. SECTIONCONTORTA1
Authors: Sheath Robert G. , Vis Morgan L. , Cole Kathleen M. 
Published: October 2004

ABSTRACTMultivariate morphometrics and image analysis were used to determine the number of well‐distinguished infra‐generic taxa in the sectionContortaof the freshwater red algal genusBatrachospermumin North America. Five groupings were distinguished from 29 populations examined from New Mexico to Costa Rica. These entities were statistically related to 12 type specimens reported from or similar to North American populations. The following taxa were recognized:B. ambiguumMontagne (syn.B. bicudoiNecchi andB. basilareFlint et Skuja)B. globosporumIsraelson (syn.B. cipoenseKumano et Necchi andB. jolyiNecchi),B. intortumJao,B. louisianaeSkuja andB. procarpumSkuja var.americanumvar. nov. The new variety differs from the nominate variety in having significantly larger whorls and smaller carpogonia.Batrachospermum ambiguum, B. louisianae, andB. procarpumvar.americanumoccur in low ion waters (10–187 μS·cm−1), whereasB. intortumandB. globosporumare found in high ion waters (260–1760 μS·cm−1). Detailed descriptions and a key to the five taxa are given.
VALVE AND BAND MORPHOLOGY OF SOME FRESHWATER DIATOMS. V. VARIATIONS IN THE CINGULUM OF PLEUROSIRA LAEVIS (BACILLARIOPHYCEAE)1
Authors: Johnson Lisa M. , Rosowski James R. 
Published: October 2004

ABSTRACTFrustule ultrastructure of Pleurosira laevis (Ehr.) Compère from an epilithon sample collected from the Missouri River was examined using scanning electron microscopy. Valve characteristics were similar to those found by other authors, whereas certain features of the cingulum were new. The cingulum consists primarily of three girdle bands (a valvocopula and two pleurae). The valvocopula can be complete but open at one end, below the ocellus. However, it is more commonly bisegmented, with two narrow and severable connecting points located in the pars interior region underlapping the mantle. The first and second pleurae are either biligulate or uniligulate and closed, but the former, when uniligulate, may be an open band as well. The second pleura is narrower and more delicate than the first. When a natural cleavage of a band subtends a ligula, the band is prone to break along the cleavage during specimen preparation, thus making difficult the assessment of band form and cingulum arrangement. Regions of band overlap have smooth poreless edges, whereas those of underlap are rimmed with either fine fimbriae or, occasionally, a coarser comblike fringe. The variability of the bands results in a cingulum that can be assembled in at least four different arrangements.
RELATIONSHIP BETWEEN PHOTOSYNTHETIC OXYGEN CYCLING AND CARBON ASSIMILATION IN SYNECHOCOCCUS WH7803 (CYANOPHYTA)1
Authors: Kana Todd M. 
Published: October 2004

ABSTRACTMass spectrometric analysis of oxygen uptake and evolution in the light by marine Synechococcus WH7803 indicated that the respiration rate was near zero at low irradiance levels but increased significantly at high irradiances. The light intensity (Ir) at which oxygen uptake began to increase with increasing light intensity depended on the growth irradiance of the culture. In each case, Ir coincided with the minimum light intensity for saturation of carbon assimilation (Ik). At irradiances >Ir, net oxygen evolution rates paralleled carbon assimilation rates. Oxygen uptake at high light intensities was inhibited by DCMU, indicating that oxygen uptake was due to Mehler reaction activity. The onset of Mehler activity at Ik supports the idea that oxygen becomes an alternative sink for electrons from photosystem I when NADPH turnover is limited by the capacity of the dark reactions to utilize reductant.
ULTRASTRUCTURE AND IMMUNOLOCALIZATION OF PHYCOBILIPROTEINS AND RIBULOSE 1,5‐BISPHOSPHATE CARBOXYLASE/OXYGENASE IN THE MARINE CYANOBACTERIUM TRICHODESMIUM THIEBAUTII1
Authors: Siddiqui Pirzada J. A. , Carpenter Edward J. , Bergman Birgitta 
Published: October 2004

ABSTRACT Trichodesmium thiebautii Gomont, a marine planktonic diazotrophic cyanobacterium, has an unusual subcellular arrangement. To identify subcellular structures related to photosynthesis, antibodies against phycoerythrin, phycocyanin, and ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) were used together with an immuno‐gold labeling technique and electron microscopy. Thylakoid membranes, identified by transmission electron microscopy and phycobiliprotein labeling, were arranged as a loose network throughout all cells. Rubisco showed a particularly intense localization in medium electron‐dense polyhedral bodies, therefore identified as carboxysomes. The average density of the carboxysomal Rubisco label was about five times higher than that in the cytoplasm. The carboxysomes (4–11 per cell section) were scattered throughout the cytoplasm. These data, together with those obtained from double immunolabeling experiments using nitrogenase (Fe‐protein) and Rubisco antibodies, revealed that Trichodesmium contains both N2‐ and CO2‐fixing proteins within the same cell. This is in contrast to the previous concept of a spatial segregation of the two processes in Trichodesmium and demonstrate that nitrogenase‐containing cells are not comparable to heterocysts in this context.
POLYCLONAL ANTIBODIES AGAINST IRON‐SUPEROXIDE DISMUTASE FROM ESCHERICHIA COLI B CROSS‐REACT WITH SUPEROXIDE DISMUTASES FROM SYMBIODINIUM MICROADRIATICUM (DINOPHYCEAE)1
Authors: Matta Jaime L. , Govind Nadathur S. , Trench Robert K. 
Published: October 2004

ABSTRACTAssays for superoxide dismutases (SODs) were performed using cell‐free extracts of the symbiotic dinoflagellate Symbiodinium microadriaticum Freudenthal (emend Trench and Blank) after separation in undenatured polyacrylamide gels. Using appropriate inhibitors (KCN and H2O2) we detected the presence of Cu/Zn‐, Mn‐, and Fe‐SODs. In immunoblot assays, polyclonal antibodies against Fe‐SOD from Escherichia coli B cross‐reacted with two major polypeptides in the water‐soluble fraction and one polypeptide in the Triton X‐100‐solubilized pellet fraction. The polypeptide common to both fractions, with a relative molecular mass of 43.5 kDa, was identified as Mn‐SOD. In S. microadriaticum, FeSOD, found only in the water‐soluble fraction, appears to be monomeric, with a relative molecular mass of 49.5 kDa.
DNA NUCLEOSIDE COMPOSITION AND METHYLATION IN SEVERAL SPECIES OF MICROALGAE1
Authors: Jarvis Eric E. , Dunahay Terri G. , Brown Lewis M. 
Published: October 2004

ABSTRACTTotal DNA was isolated from 10 species of microalgae, including representatives of the Chlorophyceae (Chlorella ellipsoidea, Chlamydomonas reinhardtii, and Monoraphidium minutum), Bacillariophyceae (Cyclotella cryptica, Navicula saprophila, Nitzschia pusilla, and Phaeodactylum tricornutum), Charophyceae (Stichococcus sp.), Dinophyceae (Crypthecodinium cohnii), and Prasinophyceae (Tetraselmis suecica). Control samples of Escherichia coli and calf thymus DNA were also analyzed. The nucleoside base composition of each DNA sample was determined by reversed‐phase high performance liquid chromatography. All samples contained 5‐methyldeoxycytidine, although at widely varying levels. In M. minutum, about one‐third of the cytidine residues were methylated. Restriction analysis supported this high degree of methylation in M. minutum and suggested that methylation is biased toward 5′‐CG dinucleotides. The guanosine + cytosine (GC) contents of the green algae were, with the exception of Stichococcus sp., consistently higher than those of the diatoms. Monoraphidium minutum exhibited an extremely high GC content of 71%. Such a value is rare among eukaryotic organisms and might indicate an unusual codon usage. This work is important for developing strategies for transformation and gene cloning in these algae.
CONCORDANCE OF MOLECULAR AND ULTRASTRUCTURAL DATA IN THE STUDY OF ZOOSPORIC CHLOROCOCCALEAN GREEN ALGAE1
Authors: Lewis Louise A. , Wilcox Lee W. , Fuerst Paul A. , Floyd Gary L. 
Published: October 2004

ABSTRACTAlternative evolutionary hypotheses generated from features of vegetative cell morphology and motile cell ultra‐structure were investigated using a molecular data set. Complete nuclear‐encoded small subunit (18S) ribosomal RNA (rRNA) gene sequences were determined for six species (three each) of the chlorococcalean green algae “Neo chloris” andCharacium. Based on motile cell ultra‐structure, it was previously shown that both genera could be separated into three distinct groups possibly representing three separate orders and two classes of green algae. 18S rRNA gene sequences were also obtained for three additional taxa,Dunaliella parvaLerche,Pediastrum duplexMeyen, andFriedmannia israelensisChantanachat and Bold. These organisms were selected because each, in turn, is a representative of one of the three ultrastructural groups into which theNeochlorisandCharaciumspecies are separable. Phylogenetic analyses utilizing the molecular data fully support the ultrastructural findings, suggesting that the similar vegetative cell morphologies observed in these organisms have resulted from convergence.
ASSESSING THE RELATIONSHIPS OF AUTOSPORIC AND ZOOSPORIC CHLOROCOCCALEAN GREEN ALGAE WITH 18S rDNA SEQUENCE DATA1
Authors: Wilcox Lee W. , Lewis Louise A. , Fuerst Paul A. , Floyd Gary L. 
Published: October 2004

ABSTRACTWe examined the relationships of autosporic and zoosporic taxa in the Chlorococcales by analyzing available complete nuclear‐encoded small‐subunit (18S) rRNA gene sequences along with two new sequences fromHydrodictyon reticulatum(L.) Lagerh. andNeochloris vigenisArchibald. Some autosporic taxa grouped with the coenobial hydrodictyacean algae and related unicellular organisms having directly opposed basal bodies. These includeScenedesmus obliquus(Turp.) Kütz. andChlorella fuscavar. vacuolata Shihira et Krauss. Other autosporic organisms, includingChlorella kessleriFott et Novakova,C. minutissimaFott et Novakova,C. pro‐tothecoidesKrug.,C. vulgarisBeij.,Nanochlorum eucaryotumWilhelm, Eisenbeis, Wild, et Zahn, andPrototheca wickerhamiiSoneda et Tubaki, form a separate group. Of the zoosporic taxa examined, this group would appear to have the greatest affinity to organisms having a counterclockwise displacement of basal bodies, the Pleurastrophyceae. Beyond the fact thatAnkistrodesmus stipitatus(=A. falcatusvar.stipitatus(Chodat) Lemm.) does not group with the latter organisms, its position remains in doubt. None of the autosporic taxa appear to be closely related to chlorophycean organisms possessing a clockwise basal body displacement.
AXENIC CULTURES OF ACETABULARIA (CHLOROPHYTA): A DECONTAMINATION PROTOCOL WITH POTENTIAL APPLICATION TO OTHER ALGAE1
Authors: Hunt Brenda E. , Mandoli Dina F. 
Published: October 2004

ABSTRACTWe developed an easy, reliable decontamination protocol for caps of Acetabularia acetabulum (L.) Silva; with minimal labor hundreds of caps can be decontaminated. In addition, cysts isolated from these caps do not exhibit dormancy and can be used immediately to establish large populations of axenic cell cultures. This method consists of three successive incubations: 1) proteinase K/sodium dodecyl sulfate/1,3‐bis[tris(hydroxymethyl)‐methylamino]propane for 1 h, 2) mild silver protein for 5 min, and 3) an antibiotic solution (neomycin, chloramphenicol, nystatin, ampicillin, streptomycin)for 3 days. This protocol eliminates bacterial, algal, fungal, and yeast contaminants. It is useful for decontaminating caps from lab cultures and caps collected from the wild and may also be effective in decontaminating the reproductive structures of other algae. Cyst dormancy was reduced from 15 weeks to less than 1 week, which represents a 40% reduction of the life cycle of A. acetabulum. We routinely obtained 90‐100% gamete release from cysts 3‐14 days after they were made axenic. The component of our culturing methods that allows gamete release without a “dormant” period is unknown.
PHYSIOLOGICAL INDICATORS OF NUTRIENT DEFICIENCY IN CLADOPHORA (CHLOROPHYTA) IN THE CLARK FORK OF THE COLUMBIA RIVER, MONTANA1
Authors: Lohman Kirk , Priscu John C. 
Published: October 2004

ABSTRACTCellular nutrient concentrations and nutrient uptake rates of Cladophora glomerata (L.) Kuetzing were determined during summer and fall in 1989–1990 at a site on the upper Clark Fork of the Columbia River, Montana. Both physiological tests indicated that Cladophora growth is likely to be limited by nitrogen during late summer‐early fall. Maximum uptake rates of ammonia‐N and nitrate‐N were 5935–6991 and 507–984 μg · g DW−1· h−1, respectively, during July–October when dissolved inorganic nitrogen (DIN) concentrations in the river were less than 10 μg · L−1. During November‐December, when DIN was 72–376 μg · L−1, maximum ammonia‐N uptake was 1137–1633 μg · g DW−1· h−1 and maximum nitrate‐N uptake was 0–196 μg · g DW−1· h−1. Cellular nitrogen during summer–early fall was 0.78–1.80% of Cladophora dry weight, frequently at or below 1.1%, a level suggested as a critical minimum N concentration for maximum growth. In contrast, cellular P was 0.18–0.36% of dry weight, 3–6 times the suggested critical P concentration of 0.06%. Molar ratios of cellular N:P (< 16:1) and DIN: SRP (< 4:1) during late summer‐early fall also indicated potential N limitation. Cellular N and P from Cladophora collected from a second site influenced by a municipal wastewater discharge in 1990 displayed similar seasonal trends. At both sites, seasonal fluctuations in DIN were closely tracked by changes in cellular N, Cellular P, however, increased through the growing season despite declining levels of SRP in the river.
OCCURRENCE OF OCTADECAPENTAENOIC ACID IN LIPIDS OF A COLD STENOTHERMIC ALGA, PRYMNESIOPHYTE STRAIN B1
Authors: Okuyama Hidetoshi , Morita Naoki , Kogame Kazuhiro 
Published: October 2004

ABSTRACTThe fatty acid composition of the prymnesiophyte strain B, a cold stenothermic microalga, was examined. The major fatty acids derived from the total lipids in this strain were myristic (14:0), palmitic (16:0), oleic (18:1ω9), linoleic (18:2ω6), octadecatetraenoic (18:4ω3), octadecapentaenoic (18:5ω3), and docosahexaenoic (22:6ω3) acids. Octadecapentaenoic acid (18:5ω3) was an unusual component and was characterized by mass spectrometry, infrared absorption spectrometry, and proton nuclear magnetic resonance spectrometry. Saturated fatty acids (14:0 and 16:0) and 18:5ω3 were distributed at significant levels in the major classes of galactolipids (monogalacto‐syldiacylglycerol, digalactosyldiacylglycerol, and sulfoqui‐novosyldiacylglycerol), phospholipids (phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine), and neutral lipids with the exception that phosphatidylethanolamine contained only trace amounts of 14:0. By contrast, 22:6ω3 was distributed in phospholipids and neutral lipids.A decrease in growth temperature from 5°C to 2°C was accompanied by a significant increase in levels of 18: 5ω3 and 18:4ω3 with a concomitant decrease in the level of saturated fatty acids, whereas the level of 22:6ω3 was scarcely changed. These results suggest that, in prymnesiophyte strain B, eighteen‐carbon polyunsaturated fatty acids with more than three double bonds, 18:5ω3 in particular, serve as modulators of membrane fluidity. The potential role of 18:5ω3 as a specific marker for prym‐nesiophytes is also discussed.