bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEDIMENTATION STUDIES OF RED ALGAL SPORES1
Authors: Okuda Takeo , Neushul Michael 
Published: August 2007

ABSTRACTMore than 1000 spores from 11 species of red algae were collected; their differences in size and sinking rates were measured using a new micro‐video technique. A relationship between size and sinking rate was shown with larger spores generally sinking faster than smaller ones. Variability in spore size, or lack thereof, is a species characteristic. Cryptopleura violacea (J. G. Ag.) Kylin and Neoagardhiella baileyi (Kutz.) Wynne and Taylor were found to produce a wide range of spore sizes. Such variability in size may be related to differences in spore formation. Centrifugation was used to separate the contents of spores to show differences in them. The ecological implications of these observations are considered.
POLYSACCHARIDES FROM THE ENVELOPES OF HETEROCYSTS AND SPORES OF THE BLUE‐GREEN ALGAE ANABAENA VARIABILIS AND CYLINDROSPERMUM LICHENIFORME1
Authors: Cardemil Liliana , Wolk C. Peter 
Published: August 2007

ABSTRACTThe polysaccharides from the envelopes of heterocysts of Cylindrospermum licheniforme Kütz., and of heterocysts and spores of Anabaena variabilis Kütz., like those from the differentiated cells of Anabaena cylindrica Lemm., have a 1,3‐linked backbone consisting of glucosyl and mannosyl residues in a molar ratio of approximately 3:1. As is the case with A. cylindrica the polysaccharides from A. variabilis and from the heterocysts of C. licheniforme have terminal xylosyl and galactosyl residues as side branches. In addition, the polysaccharide from C. licheniforme resembles that from A. cylindrica in having terminal mannosyl residues as side branches (absent from A. variabilis). The polysaccharides from A. variabilis resemble that from A. cylindrica in having glucose‐containing side branches (absent from the heterocyst polysaccharide from C. licheniforme), but in contrast to the polysaccharides from the other two species they also have terminal arabinosyl residues as side branches. All of the polysaccharides mentioned appear to be structurally related; we present tentative structures for those not previously investigated. In contrast, the envelope of spores of C. licheniforme contains only a largely 4‐linked galactan. The bulk of this envelope is not polysaccharide in nature, and contains aromatic groups.
COMPARATIVE KINETIC STUDIES OF PHOSPHATE‐LIMITED GROWTH AND PHOSPHATE UPTAKE IN PHYTOPLANKTON IN CONTINUOUS CULTURE1
Authors: Gotham Ivan J. , Rhee G‐Yull 
Published: August 2007

ABSTRACTA comparative kinetic study of phosphate‐limited growth and phosphate uptake was carried out in chemostat cultures of Anabaena flos‐aquae Lyng. Bréb., Ankistrodesmus falcatus (Corda) Ralfs, Asterionella formosa Hass., Fragilaria crotonensis Kitt., and Microcystis sp. Lemm. For each test organism the growth rate (μ) can be described as a function of total cell phosphorus (P), i.e. cell quota (q), or hot‐water‐extractable P (qsp).Phosphate uptake rate in each species examined was a function of external P concentration (S) and intracellular P levels. The substrate parameter for uptake (Km) remained constant at all growth rates, but the apparent maximum uptake rate (Vm') increased with decreasing μ, or q, in all test organisms. At low growth rates Vm' was greater than the calculated steady‐state uptake rate (μq) by two to three orders of magnitude because Vm' is the uptake rate at S ≫ Km and μq is the rate at S ≪ Km. The difference between Vm' and μm decreased and virtually disappeared as μ approached the physiological maximum growth rate (μm), where q = qm and S ≫ Km.An inverse relationship existed between Vm' and qsp which could be described by a function that mathematically resembles noncompetitive inhibition in enzyme kinetics. The inverse relation between Vm' and (q – q0) was described by a three‐parameter function. This empirical function provided a good description of this inverse relation over the range from Vm' at q approaching q0 up to and including calculated net, maximum uptake rates at q = qm.
AMPHIDINIUM CRYOPHILUM SP. NOV. (DINOPHYCEAE) A NEW FRESHWATER DINOFLAGELLATE. I. SPECIES DESCRIPTION USING LIGHT AND SCANNING ELECTRON MICROSCOPY1
Authors: Wedemayer Gary J. , Wilcox Lee W. , Graham Linda E. 
Published: August 2007

ABSTRACT Amphidinium cryophilum sp. nov. was found in the fall of 1979 in a small pond near Madison, Wisconsin. During the ensuing winter, it became the dominant phytoplankter. Cell numbers remained high despite a thick layer of ice and snow. After the ice melted in the spring the organism disappeared from plankton samples. A successful culture of A. cryophilum was established only when isolates were incubated at 5–7° C. It is compared with two morphologically similar species, A. amphidinioides (Geitler) Schiller and Gymnodinium inversum Nygaard. Amphidinium cryophilum is distinguished from the former by its pigmentation (golden‐yellow vs. blue‐green), the location of the cingulum, and its lack of an eyespot. It differs from the latter in cell shape, the route of the sulcus and position of the nucleus.
CYST FORMATION IN THE FRESHWATER DINOFLAGELLATE CERATIUM HIRUNDINELLA (DINOPHYCEAE)1
Authors: Chapman D. V. , Dodge J. D. , Heaney S. I. 
Published: August 2007

ABSTRACTCyst formation in Ceratium hirundinella (O. F. Müll.) Bergh was studied by light and electron microscopy, using material from several lakes and reservoirs and also laboratory cultures. Cells preparing to encyst build up large quantities of starch and lipid and at the same time reduce their other cell components. The cyst is released from the theca as a naked cell bounded by a double membrane. The most commonly found cyst deposits a layer of electron‐dense granules containing silicon on the outer membrane and lays down a cellulose‐like material between the two membranes. Cysts without the electron‐dense granules are commonly formed in cultures but rarely found in lakes. These cysts appear less resistant to decay and do not show the reorganization of cell contents for dormancy. It is suggested that C. hirundinella has both a resting cyst, forming part of the life cycle, and a temporary cyst stage.
DEUCALION GEN. NOV. AND ANISOSCHIZUS GEN. NOV. (CERAMIACEAE, CERAMIALES), TWO NEW PROPAGULE‐FORMING RED ALGAE FROM SOUTHERN AUSTRALIA1
Authors: Huisman John M. , Kraft Gerald T. 
Published: August 2007

ABSTRACTTwo new propagule‐farming red algae from southern Australia, Deucalion levringii (Lindauer) gen. et comb. nov. and Anisoschizus propaguli gen. et sp. nov., are described and defined largely on their development in laboratory culture. Deucalion is included in the tribe Compsothamnieae on the basis of its subapical procarp and alternate distichous branching. It differs from the other genera included in that tribe in that it produces 3‐celled propagules, polysporangia, a subapical cell of the fertile axis which bears 3 pericentral cells, and an apparently post‐fertilization involucre which develops from the hypogenous and sub‐hypogenous cells of the fertile axis. Its gametophyte morphology has been elucidated in culture, as only sporophytes are known from the field. Gametophytes do not appear to produce propagules. Anisoschizus is provisionally included in the tribe Spermothamnieae on the basis of its subdichotomous branching, possession of a prostrate system and the production of polysporangia. It differs from the other genera of the tribe in the production of 2‐celled propagules. Observations on the germination of the “monosporangia” of Mazoyerella arachnoidea and Monosporus spp. indicate that they are analagous to the propagules of Deucalion and Anisoschizus. The nature of these propagules and their role in recycling the parent plant are discussed and contrasted with true monosporangia. It is recommended that Monosporus be maintained as a form genus containing representatives from more than one tribe, as exemplified by plants from Lord Howe I. provisionally identified as M. indicus Boergesen which have both prostrate and erect, as opposed to only erect, axes.
THE NUCLEAR CELL CYCLE IN CHLAMYDOMONAS (CHLOROPHYCEAE)1
Authors: Coleman Annette W. 
Published: August 2007

ABSTRACTThe timing of replication and division of the Chlamydomonas Ehrenberg nucleus in the vegetative cell cycle and at gametogenesis was examined, using fluorescence microspectrophotometry with two fluorochromes, mithramycin and 4′,6‐diamidino‐2‐phenylindole (DAPI). Under appropriate conditions, these bind specifically to DNA, and the fluorescence of the DNA fluorochrome complex is a quantitative measure of the DNA content. The alga is a haplont, which produces 2n daughter cells at the time of vegetative reproduction; cytokinesis and daughter cell release lag behind karyokinesis. No nucleus was found to contain more than the 2c quantity of DNA. Hence daughter cell production proceeds by doubling of the nuclear DNA followed by karyokinesis, in a repetitive sequence. As reported previously for C. reinhardtii Dangeard, the gametes of C. moewusii Gerloff contain the 1c amount of nuclear DNA. Several conflicting interpretations of the cell cycle sequence proposed in the literature were resolved.
THE MORPHOLOGY AND DEVELOPMENT OF SOME PROMINENTLY STALKED SOUTHERN AUSTRALIAN HALYMENIACEAE (CRYPTONEMIALES, RHODOPHYTA). I. CRYPTONEMIA KALLYMENIOIDES (HARVEY) KRAFT COMB. NOV. AND C. UNDULATA SONDER1
Authors: Scott Fiona J. , Wetherbee Richard , Kraft Gerald T. 
Published: August 2007

ABSTRACTSeveral southern Australian red algae of the family Halymeniaceae (Cryptonemiales) are differentiated into hard, massive stalks and considerably softer laminar blades or phyllodes. The taxonomy, morphology and pit‐connection ultrastructure of one such species, Cryptonemia kallymenioides (Harvey) Kraft comb. nov., are compared to C. undulata Sonder, which lacks massive stalks. In both species there is extensive periodic secondary cortication of the stalks, resulting in the formation of distinct “growth rings.” The blades of C. kallymenioides appear to be seasonal and its stalks perennial, while plants of C. undulata are apparently perennial but shorter lived than C. kallymenioides. As a result, stalks in the latter can reach 2–3 cm in diameter with up to 18 growth rings, compared to the 1–2 mm diameters and up to 6 rings within the stalks of C. undulata. Heavy secondary thickening of cortical cell walls occurs in both species and confers a “woody” texture to the stalks of C. kallymeniodes. Regardless of the large differences in average stalk diameters between the two species, the pit‐connection ultrastructure from cortex to medulla shows much the same sequence of morphological modification. Pit‐connections are standard red algal structures in the outer cortex, but become increasingly convoluted on the membrane‐bound surfaces abutting cytoplasm and develop wider apertures and less dense cores with increasing distance from the stalk surface. In occasional medullary cells of C. kallymenioides, the cytoplasm disintegrates, leaving cell walls and pit‐connections to play an apparently structural role which has not been reported in other red algae. It is suggested that the increase in aperture size and surface areas of pit‐connections is compatible with their playing a role in the intercellular transport of solutes towards the inner cell layers which may, in C. kallymenioides, lie many millimeters distant.
REPRODUCTIVE DEVELOPMENT OF THE PARASITIC RED ALGA GARDNERIELLA TUBERIFERA (SOLIERIACEAE, GIGARTINALES)1
Authors: Goff Lynda J. , Hommersand Max H. 
Published: August 2007

ABSTRACTExamination of the reproductive morphology of the adelphoparasitic red alga Gardneriella tuberifera Kylin reveals that this monotypic genus is correctly placed in the family Solieriaceae (Gigartinales), to which its host Agardhiella gaudichaudii (Montagne) Silva et Papenfuss also belongs. Gardneriella is multiaxial, nonprocarpic and has an inwardly directed, three‐celled carpogonial branch. The large, reniform uninucleate auxiliary cell is distinct prior to and after fertilization. It is diploidized by an unbranched, multicellular connecting filament which lacks pit connections. One or two connecting filaments arise from each fertilized carpogonium. From the diploidized auxiliary cell, the gonimoblast initial is cut off obliquely toward the interior of the thallus. The cells of the gonimoblast fuse with adjacent unpigmented vegetative cells of Gardneriella and pigmented cells of the host. These cells become incorporated into the developing cystocarp and, from those of Gardneriella, additional short chains of gonimoblast cells arise. The mature cystocarp is placentate, radiately lobed, and lacks a surrounding involucre. Carposporangia are borne in short chains and the unpigmented carpospores are released upon the dissolution of outer vegetative cells. No ostiole is present. Gardneriella appears to be most closely related to the placentate solieriacean genera Agardhiella, Sarcodiotheca, and Meristiella and therefore this genus should be placed in the tribe recently erected for these taxa, the Agardhielleae.
PHAGOTROPHY IN GYMNODINIUM FUNGIFORME (PYRRHOPHYTA): THE PEDUNCLE AS AN ORGANELLE OF INGESTION1
Authors: Spero Howard J. 
Published: August 2007

ABSTRACTThe non‐photosynthetic phagotrophic dinoflagellate, Gymnodinium fungiforme Anissimova, ingests prey cytoplasm through a highly extensible structure called the peduncle. Although the peduncle is not observable when G. fungiforme is swimming, it protrudes 8–12 μm from the sulcal‐angular vicinity of the cell during feeding, and is approximately 3.3 μm wide when the cytoplasm of its prey is flowing through it. A circular‐oval ring of overlapping microtubules, the ‘microtubular basket’ may be seen in transmission electron microscope sections of G. fungiforme and it is inferred that this structure is a cross section of a retracted peduncle. The microtubular basket‐peduncle complex is discussed in relation to similar structures in other dinoflagellates and to the tentacle of the suctorian ciliates which have a homologous ingestion system.
CYTOMORPHOLOGICAL ASPECTS OF WOUND HEALING IN SELECTED SIPHONOCLADALES (CHLOROPHYCEAE)1
Authors: La Claire John W. 
Published: August 2007

ABSTRACTWound healing in most of the Siphonocladales investigated differs markedly from healing processes known in other coenocytic green algae. No wound plug is evident during healing in Ernodesmis verticillata (Kützing) Børgesen, Boergesenia forbesii (Harvey) Feldmann, Cladophoropsis membranacea (C. Agardh) Børgesen, Siphonocladus tropicus (Crouan) J. Agardh, Struvea elegans Børgesen, Struvea sp. and Valonia spp. The wound response in these genera involves substantial protoplasmic motility which includes retraction of the cell contents from the wound site. The protoplasm then either closes around the central vacuole (e.g. Ernodesmis) or breaks up into numerous spherical protoplasts (e.g. Valonia ventricosa J. Agardh). An intermediate pattern of healing is present in Cladophoropsis where the protoplasm usually separates into a small number of portions that individually heal in a manner similar to Ernodesmis. In all cases, the protoplasts resulting from wounding are viable. Struvea anastomosans (Harvey) Piccone, Chamaedoris sp. and Boodlea sp. are unusual in producing a distinct wound plug during healing, thereby resembling the mode of healing reported in various codialean and dasycladalean genera. It is hypothesized, that wound‐induced protoplasmic motility in the Siphonocladales involves the same cellular mechanisms that segregate protoplasm during cell, division.
CARBONIC ANHYDRASE AND CARBON FIXATION IN COCCOLITHOPHORIDS1
Authors: Sikes C. Steven , Wheeler A. P. 
Published: August 2007

ABSTRACTRates of carbon fixation in coccolithophorids in culture, unlike many other algae, are carbon limited at ambient levels of dissolved inorganic carbon (DIC). Apparently, plants often rely on activity of carbonic anhydrase (CA) to raise the level of CO2 in cells and achieve carbon saturation. However, CA activities in the coccolithophorids, Coccolithus (= Emiliania) huxleyi Lohmann and Hymenomonas (=Cricosphaera) carterae Braarud, were either not detectable or very low compared to activities in other systems, including other algae, higher plants, and representative animals. Furthermore, additions of CA to medium with 2 mM DIC at pH 8.1 resulted in nearly 30% enhancement of photosynthesis, but not coccolith formation. Although carbon fixation in coccolithophorids can be suppressed by the CA inhibitor acetazolamide, studies of CaCO3 nucleation revealed a non‐specific effect of the inhibitor. Using a 30 min assay based on pH decreases accompanying loss of dissolved. CO32‐, inhibition of crystal formation in the absence of CA at 1 mM acetazolamide was demonstrated for decalcified crab carapace, a tissue with which normal CaCo3 deposition in vitro has been shown. The results suggest only a minor role for CA in coccolithophorids.
ULTRASTRUCTURE OF THE FLAGELLAR APPARATUS OF PYROBOTRYS (CHLOROPHYCEAE)1
Authors: Hoops Harold J. , Floyd Gary L. 
Published: August 2007

ABSTRACTThe flagellar apparatus of Pyrobotrys has a number of features that are typical of the Chlorophyceae, but others that are unusual for this class. The two flagella are inserted at the apex, but they extend to the side of the cell toward the outside of the colony, here designated as the ventral side. Four basal bodies are present, two of which extend into flagella. Four microtubular rootlets alternate between the functional and accessory basal bodies. In each cell, the two ventral rootlets are nearly parallel, but the dorsal rootlets are more widely divergent. The rootlets alternate between two and four microtubules each. A striated distal fiber connects the two functional basal bodies in the plane of the flagella. Two additional, apparently nonstriated, fibers connect the basal bodies proximal to the distal fiber. Another striated fiber is associated with each four‐membered rootlet near its insertion into the flagellar apparatus. A fine periodic component is associated with each two‐membered rootlet. A rhizoplast‐like structure extends into the cell from each of the functional basal bodies. The arrangement of these components does not reflect the 180° rotational symmetry that is usually present in the Chlorophyceae, but appears to be derived from a more symmetrical ancestor. It is suggested that the form of the flagellar apparatus is associated with the unusual colony structure of Pyrobotrys.
ULTRASTRUCTURE AND TAXONOMIC POSITION OF THE RARE VOLVOCALEAN ALGA, CHLORCORONA BOHEMICA1
Authors: Hoops Harold J. , Floyd Gary L. 
Published: August 2007

ABSTRACT Chlorcorona bohemica (Fott) Fott was previously of uncertain taxonomic affinities. The cell to cell connections, which are one of the chief features of the colony, are composed of wall extensions from adjacent cells. The outgrowths are connected by a fine fibrous component extending from wall to wall. The structure of the wall itself and the cell to cell connections, are similar to those of Pyrobotrys, although the connections in the latter are not as elongated. In addition, the flagellar apparatus of Chlorocorona is very similar to the flagellar apparatus of Pyrobotrys, and unlike that in other Chlorophyceae examined. These features suggest that Chlorcorona is closely related to Pyrobotrys and should be referred to the family Spondylomoraceae.
IMPROVED PROCEDURES FOR THE CLONING AND PURIFICATION OF MICROCYSTIS CULTURES (CYANOPHYTA)1
Authors: Parker Dorothy L. 
Published: August 2007

ABSTRACTA cloned axenic culture of Microcystis Kützing was obtained by combining two procedures: a) the disaggregation of multicellular Microcystis colonies by dilution into deionized water, and b) the selective growth of Microcystis in agar media containing Na2S, which inhibited or killed the associated contaminants. Microcystis growth was stimulated by 0.3–1 mM Na2SO3, but not by 0.1–33 mM Na2SO4. Although Microcystis cells survived temporary exposure to high Na2S concentrations, their growth was not stimulated by 1 × 10−5 to 1.0 M Na2S. Possible metabolic roles of reduced sulfur compounds are considered. Microcystis colonies disaggregated to unicells at ionic concentrations below 1 mM for univalent cations, 10–100 μM for the divalent cations, and 3–10 μM for Fe3+. Higher cation concentrations prompted cell aggregation. With > 100 mM Fe3+, the Microcystis capsule appeared rust‐colored. Neither nonionic solutes nor anions detectably influenced aggregation. These observations suggest cation interactions with the Microcystis capsule and are discussed with regard to: a) possible siderochrome activity, cation chelation or luxury uptake of cations, b) the questionability of using cell aggregation as a criterion for identifying Microcystis in samples of unknown ionic strength, c) the utility of low ionic strength media in releasing contaminating bacteria from the capsule and in obtaining algal unicells for cloning, and d) a model for cation interactions with the capsule.
PHOTOSYNTHETIC AND GROWTH RESPONSES TO SALINITY IN A MARINE ISOLATE OF NANNOCHLORIS BACILLARIS (CHLOROPHYCEAE)1
Authors: Brown Lewis M. 
Published: August 2007

ABSTRACTA marine unicellular alga, Nannochloris bacillaris Naumann, was studied with respect to growth, viability and photosynthesis during the steady‐state and also subsequent to changes in the concentration of artificial seawater medium. Cells grew exponentially over the range of 2% to 300% artificial seawater, but more rapidly at lower salinities. In contrast to growth, photosynthesis as measured by both oxygen evolution and bicarbonate photoassimilation was not obviously inhibited for cells adapted within the range of 7% to 200% artificial seawater. In 300% artificial seawater, photosynthesis, especially bicarbonate photoassimilation, was inhibited. Osmotic shocks caused by transferring cells from 200% to 7% artificial seawater had little if any effect on growth, viability or photosynthesis. However, equal shocks in the upward direction (from 7% to 200% artificial seawater) caused long lag phases in growth, totally inhibited photosynthesis and very often led to cell death. Intermediate upward shocks were less deleterious, but did result in lags in growth.
GROWTH RESPONSES OF THE DIATOM, CYCLOTELLA CRYPTICA (BACILLARIOPHYCEAE), TO GIBBERELLIC ACID1
Authors: Adair Olivia V. , Miller Margaret W. 
Published: August 2007

ABSTRACTThe plant hormone, gibberellic acid (GA), stimulated growth of a marine diatom, Cyclotella cryptica Reimann, Lewin and Guillard. Four concentrations of GA (5 × 20 × 25 × and 35 × 10−6 g/mL) were added to axenic cultures of C. cryptica. Changes in cell densities, measured by cell counts and turbidimetric readings, confirmed that GA at 20 × 10−6 g/mL produced maximum stimulation. There was an increase in the total number of cells produced and a shorter lag phase of growth at this concentration. Coulter counter measurements of cell size, as well as ocular micrometer measurements, indicated there was no significant variation in cell volumes of GA grown cells over that of the controls.