bluuebunny/crossref_metadata_2025_split huggingface dataset:
CELL WALL CONSTITUENTS OF APHANOTHECE HALOPHYTICA (CYANOPHYTA)1
Authors: Jones Jay H. , Yopp John H. 
Published: August 2010

ABSTRACTSome aspects of the cell wall and extracellular polysaccharide (ECPS) of the obligate halophile Aphanothece halophytica Frémy (Chroococcales) have been investigated. Extracellular polysaccharide concentration was found to remain constant on a per cell basis in medium containing from 1–3 M NaCl. The rate of ECPS production remained constant during mid‐log growth phase and increased substantially as the culture reached stationary phase. The lipopolysaccharide of this organism was found to possess a low and unusual fatty acid content when compared to other chroococcalean forms. The cell wall appears to contain a typical gram‐negative peptidoglycan. The covalently attached protein resembles the envelope protein of extremely halophilic bacteria in its possession of a similar molar percentage of amino acids with lipophilic R‐groups and a high acidic amino acid fraction. The ECPS and cell wall fractions of A. halophytica were found to chemically more closely resemble those from other non‐halophilic, chroococcalean bluegreen algae than those from the obligately halophilic bacteria.
EFFECT OF LIGHT AND TEMPERATURE INTERACTIONS ON GROWTH OFCRYPTOMONAS EROSA(CRYPTOPHYCEAE)1
Authors: Morgan Keith C. , Kalff Jaap 
Published: August 2010

ABSTRACTCryptomonas erosaSkuja, a planktonic alga, was grown in batch culture at different combinations of light intensity and temperature, under nutrient saturation. Growth was maximal (1.2 divisions · day−1) at 23.5 C and 0.043 ly · min−1, declining sharply with temperature (0.025 divisions‐day−1at 1 C). With decreasing temperature, the cells showed both light saturation and inhibition at much reduced light intensities. At the same time the compensation light intensity for growth declined towards a minimum of slightly above 0.4 × 10−4ly · min−1(~1 ft‐c) at 1 C or <0.1 ly · day−1(PAR). Cell division was more adversely affected by low temperature than carbon uptake, and the resulting excess production of photosynthate was both stored and excreted. Extreme storage of carbohydrates resulted in cell volumes and carbon content ca. 22 and 30 × greater, respectively, than the maxima observed for cells incubated in the dark, whereas, at growth inhibitory light levels, as much as 57% of the total assimilated carbon was excreted. A marked increase in cell pigment was observed at the lowest light levels (<10−3ly · min−1), at high temperature. The growth response ofC. erosain culture provides insight into the abundance and distribution of cryptomonads and other small algal flagellates in nature.
ULTRASTRUCTURE OF MALE GAMETOGENSIS IN FUCUS SERRATUS (PHAEOPHYCEAE)1
Authors: Berkaloff Claire , Rousseau Bernard 
Published: August 2010

ABSTRACTThe main structural features of male gametogenesis in Fucus serratus L. are described. The antheridial parent cells exhibit meristematic characteristics: large nucleus, dense cytoplasm, chloroplasts with few thylakoids. Synaptonemal complexes are frequently observed in the nuclei at the same time that microtubules are very abundant around the centrioles. Meiotic spindles are intranuclear, as are the mitotic spindles of the subsequent synchronous karyokineses. A nuclear membrane is present in all stages observed. Antheridial maturation is accompanied by multiplication of mitochondria and plastids as well as development of two major kinds of “vacuoles.” Cytokinesis proceeds with the progressive fusion of one of these types of vacuoles: this mode of cytoplasmic cleavage is unique among algae. Formation and differentiation of characteristic spermatozoid organelles (flagella, eyespot, proboscis) are also described.
GAS VACUOLE COLLAPSE IN MARINE OSCILLATORIA (TRICHODESMIUM) THIEBAUTII (CYANOPHYTA) AND THE EFFECT ON NITROGENASE ACTIVITY AND PHOTOSYNTHESIS1
Authors: Carpenter Edward J. , Walsby A. E. 
Published: August 2010

ABSTRACTPhotosynthesis and nitrogenase activity (acetylene reduction) in Oscillatoria (Trichodesmium) thiebautii were significantly reduced after its gas vesicles were collapsed by pressurizing to 6·2 MPa (62 bars). The reduction in nitrogenase activity was observed with both intact and disrupted colonies, and under both aerobic and microaerobic conditions. It is unlikely, therefore, that the reduction in either process results solely from loss of gas diffusion pathways, and may simply originate from disturbance of the cellular architecture as gas vesicles are destroyed. Since nitrogenase activity of the samples was affected by gas vesicle collapse, the process presumably resides in the gas vacuolate organism (Oscillatoria) rather than in any associated bacteria which might be present.
DUDRESNAYA PATULASP. NOV., AN UNUSUAL DEEP‐WATER RED ALGA FROM FLORIDA1
Authors: Eiseman Nathaniel J. , Norris James N. 
Published: August 2010

ABSTRACTDudresnaya patulasp. nov. is described from 30–60 m depth on the east coast of Florida. The plant grows to a height of at least 10 cm, has flattened axes and main branches to 2 cm wide and 3 mm thick, and has unusually long female reproductive branches. The new species is compared to otherDudresnayaspecies in habitat, vegetative structure, and reproductive morphology.
CHEMICAL COMPOSITION AND STRUCTURE OF THE CELL WALLS OF THE CONCHOCELIS AND THALLUS PHASES OF PORPHYRA TENERA (RHODOPHYCEAE)1,2
Authors: Mukai Leonard S. , Craigie James S. , Brown Robert G. 
Published: August 2010

ABSTRACTPurified cell walls were prepared from both the conchocelis and thallus phases of Porphyra tenera (Kjellm.). The nitrogen content of cell walls from the conchocelis was significantly greater than that for the thallus cell walls, being 3.35 ± 0.26% and 2.39± 0.03%, respectively. Amino acid analysis revealed important differences. The conchocelis cell wall hydrolyzates were richer in aspartic acid, glutamic acid, methionine, and basic amino acids. The thallus cell wall hydrolyzates, however, contained much more glycine and alanine than did those of the conchocelis. Hydroxyproline was not detected in cell walls of either phase. The neutral sugar content of cell wall hydrolyzates from the thallus was more than double that from the conchocelis being 83.6% and 34.5%, respectively. The former contained predominantly mannose which accounted for 72.2% of the neutral sugars while the latter was principally galactose (49.9%) and glucose (36.4%). Methylation analysis confirmed the presence of cellulose microfibrils in the conchocelis in contrast to xylan microfibrils in the thallus. The results establish that the conchocelis and thallus phases of P. tenera differ markedly in the structure and composition of the cell walls.
EFFECTS OF THE ENCRUSTING BRYOZOAN, MEMBRANIPORA MEMBRANACEA, ON THE LOSS OF BLADES AND FRONDS BY THE GIANT KELP, MACROCYSTIS PYRIFERA (LAMINARIALES)1
Authors: Dixon John , Schroeter Stephen C. , Kastendiek Jon 
Published: August 2010

ABSTRACTJuvenile sporophytes of the giant kelp, Macrocystis pyrifera (L.) C. A. Agardh, were transplanted from local kelp beds to stations located various distances from the outfall from an electrical generating station that was known to cause an increase in the settlement of fouling organisms. Plants near the outfall became heavily fouled by the encrusting bryozoan, Membranipora membranacea (L.), and lost about one‐third of their blades during the course of the experiment. Blade loss was significantly correlated with amount of fouling. To test the hypothesis that fouling causes blade loss, we paired fouled and unfouled plants of about the same age, overall length, and number of fronds and placed them at stations in nearby kelp beds and near the outfall. At the stations in the kelp beds, the fouled plants lost blades more rapidly than the unfouled controls. However, at the station near the outfall the “control” plants quickly became fouled so there was little difference in treatments and there was no significant difference in blade loss. Plants fouled by Membranipora suffered greater blade loss than clean plants probably because fouled blades are fragile and break off easily and because fish bite off chunks of blade while foraging on the attached bryozoans.
TEMPERATURE‐GROWTH RESPONSES OF ALGAL ISOLATES FROM ANTARCTIC OASES1
Authors: Seaburg Kenneth G. , Parked Bruce C. , Wharton Robert A. , Simmons George M. 
Published: August 2010

ABSTRACTThirty‐five taxa (128 clonal cultures) of Antarctic algae isolated from various habitats were assayed for growth over a range of 2–34°C. Isolates, all unialgal and two axenic, varied markedly in their temperature‐growth responses. Only four taxa belonging to either the Chlamydomonadaceae or Ulotrichaceae were obligately cold‐adapted and incapable of growth at ≥20°C. All isolates grew at temperatures ranging from 7.5 to 18°C, and a few were incapable of growth at ≤5°C. Over one‐third of the isolates grew at 30°C, but none grew at 34°C.Percentages of cold‐adapted clones correlated well with the more stable low temperature habitats. Four chlamydomonad isolates displayed optimum temperatures for growth near their maximum temperatures for growth, both temperatures being well above those of the native habitats. This temperature‐growth response suggests a closer relationship to algae from more moderate thermal regions than one might have supposed. However, the ability to grow at low temperatures and the inability to grow at 34°C suggest that these Antarctic algae are cold temperature adapted. Growth capability at low in situ temperatures is considered more useful ecologically than physiologically‐defined categories for algae based on their maximum temperature for growth.
DIEL OSCILLATIONS IN THE PHOTOSYNTHESIS‐IRRADIANCE RELATIONSHIP OF A PLANKTONIC MARINE DIATOM1
Authors: Harding Lawrence W. , Prézelin Barbara B. , Sweeney Beatrice M. , Cox James L. 
Published: August 2010

ABSTRACTThe amplitude of diel oscillations in photosynthesis as a function of irradiance varied with the growth phase in a marine phytoplankton species. The common centric diatom (Bacillariophyta), Ditylum brightwellii (West) Grun., showed strong periodicity in the photosynthesis‐irradiance (P‐I) relationship, which damped progressively from early to late exponential and stationary phase. These findings suggest that short‐term temporal characteristics of phytoplankton production depend on factors which affect growth, and that the amplitude is most enhanced at maximal growth rates likely to be encountered in the natural environment.
GAMETOPHYTIC GROWTH BY MACROCYSTIS PYRIFERA (PHAEOPHYTA) IN RESPONSE TO VARIOUS IRON AND ZINC CONCENTRATIONS1
Authors: Kuwabara James S. 
Published: August 2010

ABSTRACTBatch culturing experiments were conducted to examine effects on Macrocystis pyrifera (L.) C. A. Agardh gametophytic growth of various iron and zinc concentrations in the chemically defined, artificial seawater medium, Aquil. A least squares fit of experimental data represented the relative importance of these micronutrient effects. Optimal iron and zinc concentrations in Aquil were estimated at 340 nM (7 × 10−11 nM as [Fe3+]) and 135 nM (6 × 10−2 nM as [Zn2+]), respectively.
TEMPORAL AMMONIUM PATCHINESS AND GROWTH RATE IN CODIUM AND ULVA (ULVOPHYCEAE)1
Authors: Ramus J. , Venable Melissa 
Published: August 2010

ABSTRACTThe growth rates of two chlorophyte macroalgae, Codium fragile and Ulva curvata, are compared in response to varied, but non‐random, NH4+ enrichments (pulses). The species were chosen to contrast radically different morphologies. Pulse frequency and pulse duration were varied independently; however, an equivalent mass of NH4+ was added in each treatment. The growth rate of Codium varied neither as a function of pulse frequency nor duration; the growth rate of Ulva varied with pulse frequency, but not pulse duration. These data are combined with life form and physiological characters, and are discussed in the context of the “function form” hypothesis. From the evidence we argue that by virtue of its life form, Ulva is capable of utilizing transiently high NH4+ concentrations and is capable of high growth rates, attributes contributing to its role as a ruderal species. In contrast, Codium's life form does not allow utilization of transiently high NH4+ concentrations or high growth rates, thereby contributing to its role as a persistent species.
TIME‐LAPSE ANALYSES OF SEXUAL ISOLATION BETWEEN TWO CLOSELY RELATED MATING GROUPS OF THE CLOSTERIUM EHRENBERG SPECIES COMPLEX (CHLOROPHYTA)1
Authors: Ichimura Terunobu , Kasai Fumie 
Published: August 2010

ABSTRACTSexual isolation between Groups A and B of Closterium ehrenbergii, two closely related species, was studied by a multiple‐choice mating method, as well as the nochoice mating method which has been used in previous work on microalgae. Time lapse photomicrographs and the difference in cell shape and size between the two mating groups allowed identification of a given cell in the mixture as either Group A or B, even when certain morphological changes occurred during the several day culture required for sexual induction. When plus and minus mating types of Group A were mixed with those of Group B (multiplechoice mating), no intergroup hybrid zygospores were formed. However, many intragroup zygospores of either Group A or B were formed. When one plus strain of Group A was mixed with one minus strain of Group B or when one plus strain of Group B was mixed with one minus strain of Group A (no‐choice mating), intergroup sexual interactions took place resulting in a small number of hybrid zygospores; however, the process took much longer than intragroup sexual interactions. It was also shown that cell size difference itself hardly affects sexual interactions between haploid and autodiploid strains of Group A. It is suggested that sexual isolation between Groups A and B would be complete in nature, although they may interact sexually in the laboratory.
VARIATIONS IN ENVELOPE MORPHOLOGY AND MINERALIZATION IN TRACHELOMONAS LEFEVREI (EUGLENOPHYCEAE)1
Authors: Dunlap John R. , Walne Patricia L. 
Published: August 2010

ABSTRACTThe mineralized envelope surrounding the trachelomonad cell is a complex of organic and inorganic components, anastomosed to form a structure that is characteristic of the species. Although there may be considerable morphological variability in envelope size, shape and ornamentation, its microarchitecture is characterized by two basic components: granular and needle‐like deposits. The present study documents for the first time that manipulation of the culture conditions results in predictable changes in envelope ultrastructure, color and elemental composition. Supplemental iron (Fe) in the culture medium results in an increase of granular components in the envelope, whereas supplemental managanese (Mn) results in an increase of needle‐like components; with nitrogen (N) supplements there is an increase of both granular and needle‐like components in the envelope. It is also shown here that autoxidation of Fe may occur, resulting in the accumulation of Fe deposits along strands of unmineralized envelope mucilage. Autoxidation and deposition of Mn do not occur.
ALGAL ASSEMBLAGES IN ANTARCTIC PACK ICE AND IN ICE‐EDGE PLANKTON1
Authors: Garrison David L. , Buck Kurt R. , Fryxell Greta A. 
Published: August 2010

ABSTRACTA significant amount of the primary production in the Southern Ocean and other ice‐covered oceans takes place in localized ice edge plankton blooms. The dynamics of these blooms appear to be closely related to seasonal melting of sea ice. Algal cells released from the ice are a possible source of ice edge planktonic assemblages, but evidence for this “seeding” has been equivocal. We compared algal assemblages in ice and water in the Weddell Sea during the austral spring of 1983 at a receding ice edge with a well‐developed ice edge bloom. The high degree of similarity between ice and water column assemblages, the spatial and temporal patterns in the distribution and abundances of species, and preliminary evidence for the viability and growth of ice‐associated species provide evidence for seeding from sea ice of some species in Antarctica.
ULTRASTRUCTURE OF A NEW INTRACELLULAR SYMBIOTIC ALGA FOUND WITHIN PLANKTONIC FORAMINIFERA1
Authors: Gastrich Mary Downes 
Published: August 2010

ABSTRACTA small intracellular eukaryotic algal symbiont, 1.5–3.5 μm in diameter, occurs abundantly and persistently in nine planktonic Foraminifera host species. This alga is different from the dinoflagellate, from 8–12 μm in diameter, known to occur in the four spinose species Orbulina universa, Globigerinoides sacculifer, G. ruber, and G. conglobatus. Transmission and epifluorescent microscopy were used to confirm the presence cophyta. The evidence supporting this classification includes the presence of a chloroplastic endoplasmic reticulum surrounding the plastids and tubular cristae, as opposed to flattened cristae, in the mitochondria. Three classes of algae may be represented including the Chrysophyceae, Bacillariophyceae, and Prymnesiophyceae.Ultrastructural analysis indicated that the alga in the spinose Globigerinella aequilateralis resembles a prymnesiophyte because the chloroplasts lack a girdle lamella. The algae in the non‐spinose species and the short‐spined Globigerina cristata resemble endocytic chrysophytes or diatoms because of the presence of a girdle lamella. Ultrastructural characteristics of the chrysophycophycean alga present in planktonic Foraminifera are discussed and compared to those of non‐dinoflagellate symbiotic algae associated with other invertebrate hosts.
EFFECTS OF SELENIUM DEFICIENCY ON THE MORPHOLOGY AND ULTRASTRUCTURE OF THE COASTAL MARINE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE)1,2
Authors: Doucette Gregory J. , Price Neil M. , Harrison Paul J. 
Published: August 2010

ABSTRACTThe effects of selenium deficiency on the siliceous and nonsiliceous components of the planktonic marine diatom Thalassiosira pseudonana (Hust.) Hasle and Heimdal (clone 3H) are examined using light and electron microscopy. Selenium deficiency induces elongation along the pervalvar axis initially as a result of chain formation caused by the failure of sibling cells to separate and subsequently by cell elongation via the production of hyaline girdle bands. In Se‐deficient cultures cell elongation involves the blockage of both mitotic and cytokinetic components of cell division. Selenium deficiency results in ultrastructural alterations in the reticular membrane system and in mitochondrial and chloroplast membranes. Various types of inclusions are seen in vacuolar areas and the accumulation of lipid reserves is evident in Se‐deficient cells. These results provide indirect evidence for a metabolic Se requirement in this algal species.
REGULATION OF GAS VESICLE CONTENT AND BUOYANCY IN LIGHT‐OR PHOSPHATE‐LIMITED CULTURES OF APHANIZOMENON FLOS‐AQUAE (CYANOPHYTA)1
Authors: Konopka Allan , Kromkamp Jacco , Mur Luuc R. 
Published: August 2010

ABSTRACTMeasurements of the gas vesicle space in steady‐state light or phosphate‐limited cultures of Aphanizomenon flos‐aquae Ralfs, strain 7905 showed that gas vesicle content decreased as energy‐limited growth rate increased but was the same at several phosphate‐limited growth rates. Upon a decrease in growth irradiance, gas vesicle content did increase in phosphate‐limited cultures, but the cultures remained nonbuoyant as long as P was limiting. Buoyant, energy‐limited cultures lost their buoyancy in less than 2 h when exposed to higher irradiances. The primary mechanism for buoyancy loss was the accumulation of polysaccharide as ballast. Collapse of gas vesicles by turgor pressure played a minor role in the loss of buoyancy. When cultures were exposed to higher irradiances, cells continued to synthesize gas vesicles at the same rate as before the shift for at least 1 generation time. The amount of ballast required to make individual filaments in the population sink varied 4‐fold. This variation appears to be due to differences in gas vesicle content among individual filaments.
THE ROLE OF DIATOMS IN STROMATOLITE GROWTH: TWO EXAMPLES FROM MODERN FRESHWATER SETTINGS1
Authors: Winsborough Barbara M. , Golubić Stjepko 
Published: August 2010

ABSTRACTSome modern laminated and calcified stromatolitic structures are partially or completely formed by eukaryotes. Diatom populations in freshwater environments with elevated ionic concentrations contribute to calcite precipitation, and the formation of distinctive mineral‐rich stromatolitic laminae. Two types of stromatolite‐forming diatom populations were observed. In the first example, in stromatolies growing on a quarry ledge near Laegerdorf, North Germany, calcite crystals with biogenic imprints form around polysaccharide stalks of the diatom Gomphonema olivaceum var. calcarea (Cleve) Cleve‐Euler. These individually precipitated crystals eventunally become cemented together in layers, forming rigid, laminated stromatolitic deposits which drape over the quarry ledge. In the second example, in stromatolites forming in a shallow stream near Cuatro Ciénegas, Coahuila, Mexico, diatomaceous laminae also form by the accumulation of carbonate particles in a matrix of diatoms and their extracellular polysaccharide products. These laminae become thick enough to drape over individual stromatolite heads. The diatoms responsible for these deposits are Amphora aff. A. Katii Selva, Nitzschia denticula Grun., and six other species. At Cuatro Ciénegas, in addition to the diatomaceous laminae, carbonate‐rich cyanobacterial layers, dominated by two cyanobacterial species with different fabrics and porosities, are also present and contribute substantially to the growth of the stromatolites. In both the Laegerdorf and Cuatro Ciénegas examples, entire stromatolites or thick laminations on stromatolites are built by a small number of diatom species which produce copious amounts of extracellular stalk, gel, and sheath material, a property they share with cyanobacterial stromatolite builders.
SYSTEMATICS AND ECOLOGY OF LYNGBYA SPP. AND ASSOCIATED SPECIES (CYANOPHYTA) IN A NEW ENGLAND SALT MARSH1,2
Authors: Baker Kathleen Kromer 
Published: August 2010

ABSTRACTField populations of the most abundant filamentous blue‐green algae (cyanobacteria) from a northern New England salt marsh were examined for the presence of natural morphological clusters. A continuum in the distribution of average cell sizes and shapes for individual trichomes was evident. However, there was a high frequency of certain cell sizes (six cluster, which were also separated by several qualitatives characters (end cell shape, granule location, and cell color). In clonal cultures the trichomes of these culsters maintained the morphology of the original isolated trichome and thus morphology apperated to be stable. The clusters were either named according to Gietler's (1932.) terminology or assigned numbers if no adequate descriptions were availble: (1) Lyngyya and Phormidium spp., (2) Microcoleus chthonoplastes Thur. (3) Lyngbya sp.1, (4)Lyngbya sp. 2 (5) Lyngbya aestruarii (Mert.) Liebmann, and, (6) Lyngbya aestuarii (mert. Liebmann, and, (6) Lyngbya sp. 3. All goups had maximum asbundance in late summer. Microcoleus chthonoplastes occurred throughtout the; year, while Lyngbya aestuarri and Lynobya sp. 3 occurred throughout the summer and fall. It is concluded that both field and culture information are useful in enhancing our knowledge of blue‐green algal systematics.