bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF HYDROXAMATE SIDEROPHORES (STRONG Fe (III) CHELATORS) ON THE GROWTH OF ALGAE1
Authors: Bailey Kevin M. , Taub Frieda B. 
Published: August 2007

ABSTRACTVarying concentrations of Fe were tested with three hydroxamate siderophores to demonstrate the interactions affecting growth of Chlamydomonas reinhardtii and Chlorella vulgaris. Schizokinen was purified from the excretions of the blue‐green alga Anabaena sp. grown in low‐Fe medium. Chlamydomonas reinhardtii was inhibited by schizokinen when in molar excess of the Fe concentration; the inhibition was overcome with excess Fe. The growth of C. vulgaris was not affected by this chelator. Results with desferrioxamine were similar. A weaker chelator, rhodorulic acid, did not inhibit the growth of either alga. Low concentrations of the chelators may stimulate algal growth when Fe precipitates are hydrolyzed. Since different algae respond differently to the presence of the chelators, the observed interactions could be important in determining competitive relationships when Fe is limiting. If an alga can excrete a strong chelating agent, as does Anabaena, algae lacking the ability to compete with the chelator may not grow.
ANATOMY AND ALGAL‐FUNGAL INTERACTIONS IN THE LICHENUSNEA CAVERNOSA1
Authors: Malachowski James A. , Baker Karen K. , Hooper Gary R. 
Published: August 2007

ABSTRACTInteractions between fungal and algal components ofUsnea cavernosaTuck, were demonstrated with transmission and scanning electron microscopy. Cells were observed in very close associations, and both intrawall and intracellular haustoria were evident. In addition, a previously unreported type of interaction was discovered which consisted of an extracellular hyphal sheath with distinctive protuberances which penetrated into the algal cell wall. Internal environmental factors which may bear on the types of cellular interactions were evaluated by dividing the lichen thalius into three artificial regions using spatial and temporal criteria. Fungal hyphae in the various internal anatomical zones (e.g., cortex, medulla, central cord) demonstrated differences in cell wall structure and extracellular material produced.
PHOSPHATE UPTAKE BY SYNECHOCOCCUS LEOPOLIENSIS (CYANOPHYCEAE): ENHANCEMENT BY CALCIUM ION1
Authors: Rigby Cynthia H. , Craig Susan R. , Budd Kenneth 
Published: August 2007

ABSTRACTThe influence of metallic, cations (added at 10 μM‐1 mM) on the uptake of orthophosphate from 0.2–10 μM solution by Synechococcus leopoliensis (Racib.) Komarek was investigated. All cations tested except Mg2+ and Zn2+ stimulated phosphate uptake. The most pronounced stimulation of phosphate uptake was caused by Ca2+·Ca2+ markedly decreased the half‐saturation concentration for orthophosphate uptake, apparently by acting upon the metabolic processes of phosphate transport into the cell. Phosphate did not influence Ca2+ fluxes across the cell‐surface.
STRUCTURE AND PHYCOBILIPROTEIN COMPOSITION OF PHYCOBILISOMES FROM GRIFFITHSIA PACIFICA (RHODOPHYCEAE)1
Authors: Gantt Elisabeth , Lipschultz Claudia A. 
Published: August 2007

ABSTRACTPhycobilisomes in Griffithsia pacifica are closely spaced on the thylakoid membrane. By negative staining, attached and isolated phycobilisomes have been shown to have a block shaped appearance. They are 63 nm long, 38 nm high, and 38 nm wide, making them the largest thus far reported. Isolated phycobilisomes, shown to be functionally intact by their 675 nm fluorescence emission (excitation 545 nm) were stable for more than a day. Phycobiliproteins from dissociated phycobilisomes, separated on sucrose gradients and by polyacrylamide electrophoresis, yielded large (R‐) and small (r‐) molecular weight species of phycoerythrin (ca. 4:1 respectively) constituting 89% of the phycobiliprotein content, with R‐phycocyanin 8%, and allophycocyanin 3% accounting for the rest. Phycobilisomes of Griffithsia pacifica and Porphyridium purpureum (Bory) Drew and Ross (P. cruentum) are structurally very similar with phycoerythrin being on the outside and surrounding a core of R‐phycocyanin and allophycocyanin.
GROWTH RATES OF PSEUDOPEDINELLA PYRIFORME (CHRYSOPHYCEAE) IN RESPONSE TO 75 COMBINATIONS OF LIGHT, TEMPERATURE AND SALINITY1
Authors: Ostroff Cynthia R. , Karlander Edward P. , Van Valkenburg Shirley D. 
Published: August 2007

ABSTRACTClonal cultures were established of single cells of Pseudopedinella pyriforme Carter isolated from the Chesapeake Bay. Axenic cultures were incubated at 5, 10 and 15 C; in 2 1/2, 5, 7 1/2, 10 and 15‰; and at 143, 285, 428, 571 and 714 μW/cm2 white light. Maintainable growth rates were calculated from absorbance readings taken for 3 to 5 days from acclimated cultures. The maximum number of doublings per day was 0.9 at 2 1/2‰ salinity, 571 μW/ cm2 and 15 C. A salinity of 5 ‰ produced the fastest growth at most light intensities up to 428μW/cm2 and temperatures of 5, 10 and 15 C.
ENVIRONMENTAL CONTROL OF PITHOPHORA OEDOGONIA (CHLOROPHYCEAE) AKINETE GERMINATION1
Authors: Spencer David F. , Volpp Ted R. , Lembi Carole A. 
Published: August 2007

ABSTRACTAbundance of Pithophora oedogonia akinetes displayed seasonal changes, being greatest in winter and lowest in summer. Akinete abundance showed significant (P < 0.001) negative correlations with photoperiod(r = ‐0.53) and water temperature (r= ‐0.75) during the period February 1978 through June 1979. Experiments in which akinete germination was studied in response to manipulations of nutrients (NO3‐N and PO4‐P), photoperiod and temperature indicated that temperature was the primary factor regulating the timing of the vernal flush of akinete germination observed in Surrey Lake.
COMPARATIVE PHYSIOLOGICAL STUDY OF MARINE DIATOMS AND DINOFLAGELLATES IN RELATION TO IRRADIANCE AND CELL SIZE. II. RELATIONSHIP BETWEEN PHOTOSYNTHESIS, GROWTH, AND CARBON/CHLOROPHYLL a RATIO1,2
Authors: Chan Augustine T. 
Published: August 2007

ABSTRACTPhotosynthetic rates, growth rates, cell carbon, cell protein, and chlorophyll a content of two diatom and two dinoflagellate species were measured. The microalgae were chosen to have one small and one large species from each phylogenetic group; the two size categories differed from each other by 1.5 orders of magnitude in terms of cell carbon or cell protein. The cultures for the experiments were grown under continuous light at an irradiance high enough for the light‐saturation of growth for all four species. The four species were found to have similar maximum photosynthetic rates per unit chlorophyll a. The diatom species showed lower carbon/chlorophyll a ratios and higher photosynthetic rates per unit carbon than the dinoflagellates. The higher growth rates of the diatoms were shown to be related to their higher photosynthetic rates per unit carbon. The ecological significance of the physiological difference between these two groups of microalgae is discussed.
CALCIFICATION BY COCCOLITHOPHORIDS: EFFECTS OF pH AND Sr1
Authors: Sikes C. Steven , Wilbur Karl M. 
Published: August 2007

ABSTRACTCells of Coccolithus huxleyi which fail to deposit CaCO3 and form coccoliths often occur as unwanted components in cultures used for studies of calcification. Non‐calcified cells generally cannot be made to recalcify, but they can be removed from cultures by treatment at elevated pH or by a method based on faster sinking of calcified cells. Lowering the concentrations of nitrate, phosphate, or trace metals in the medium did not restore calcifying ability of non‐calcified cells. However, addition of strontium did promote recalcification of decalcified Cricosphaera carterae grown under calcium limitation. Strontium seemed to promote coccolith attachment to cells rather than to affect calcium uptake or coccolith formation itself.
DISTRIBUTION AND PHYSIOLOGICAL DETERMINANTS OF BLUE‐GREEN ALGAL NITROGEN FIXATION ALONG A THERMOGRADIENT1
Authors: Wickstrom Conrad E. 
Published: August 2007

ABSTRACTThe capacity of thermal algal‐bacterial mats to fix nitrogen (N2) was examined in an alkaline thermal stream, Rabbit Creek, of Yellowstone National Park. Nitrogenase activity and nitrogen‐fixation rates of mat cores placed in serum bottles and incubated in situ were estimated by the acetylene‐reduction technique. Active nitrogenase was not detected at 60 or 65 C in either the blue‐green algal or bacterial undermat components of the mats. Acetylene was reduced by all mats ≤55 C along the thermogradient; mean fixation estimates for the mats ranged from 7 to 5,028 nmoles N2 fixed · mg Chl a−1· hr−1. Maximum fixation occurred at 35 C in the stream; statistical comparison of mean rates ordered the thermogradient mats according to estimated activities: 35 > 40 > 30 > 50 ≥ 55 ≥ 45 C. Mats (≤40 C) dominated by species of Calothrix accounted for ca. 97% of the total nitrogen fixation observed in the stream; the remaining activity was associated with mats containing Mastigocladus laminosus Cohn. Light intensity significantly affected fixation rates of the Calothrix mats which responded in a linear fashion from 9–100% full sunlight (ca. 1,900 μEin · m−2· sec−1). Calothrix mats from 30 and 40 C had maximum nitrogenase activity at their growth temperature suggesting that nitrogen fixation along the thermogradient was optimally adapted to in situ temperatures.
TAXONOMIC SIGNIFICANCE OF NUCLEUS‐MICROBODY ASSOCIATIONS, SEGREGATED NUCLEOLI AND OTHER NUCLEAR FEATURES IN SIPHONOUS GREEN ALGAE1
Authors: Roth William C. , Friedmann E. Imre 
Published: August 2007

ABSTRACTOn the basis of fine‐structural features of nuclei the “true” siphonous green algae (Eusiphoniidae) are divided into three groups. In theCodiumgroup nuclei are generally similar to those in most other algae. ThePenicillusgroup is characterized by the association of microbodies with nuclei. In theAvrainvilleagroup nucleoli are segregated into a granular and a fibrillar component. This condition, known as macrosegregation, persists throughout the vegetative phase of the life history and may indicate a peculiar ribosomal RNA cycle.ThePenicillusgroup corresponds to the order Caulerpales Feldmann.AvrainvilleaandCladocephalusprobably constitute a new order.Blastophysa,although having a type of segregated nucleoli, is probably more closely related to Siphonocladales than to any order in Eusiphoniidae.
OBSERVATIONS ON THE PECULIAR DIURNAL MIGRATION OF A RED TIDE DINOPHYCEAE IN TROPICAL SHALLOW WATERS1
Authors: Horstmann Ulrich 
Published: August 2007

ABSTRACTThe dinoflagellate Peridinium cf. quinquecorne Abé forms red tide‐like blooms in eutrophic shallow waters in the Philippines. The organism moves into a distinct near‐surface layer when intensive solar radiation occurs, but only during the incoming tide. Shortly before high tide, regardless of light levels, the dinoflagellates seem to disappear. Simple experiments show that once intensive radiation has been reduced Peridinium quinquecorne moves out of the water column and attaches itself to solid objects away from the light. The morphology of the organism, especially as related to attachment, was studied through SEM. Its high swimming velocity and the reaction to radiation and tidal changes are described. The possibility that, superimposed on its reaction to light, this dinoflagellate may follow intrinsic tide‐dependent oscillations is discussed.
TRACHELOMONAS HISPIDA VAR. CORONATA (EUGLENOPHYCEAE). I. ULTRASTRUCTURE OF CYTOSKELETAL AND FLAGELLAR SYSTEMS1,2
Authors: West Larry K. , Walne Patricia L. , Rosowski James R. 
Published: August 2007

ABSTRACT Trachelomonas hispida var. coronata Lemm. has a fibrous, mucilaginous, ovoid, mineralized envelope (lorica), the ornamentation and coloration of which are capricious in culture. Cells exhibit a radial distribution of most organelles: (i) A cortical endoplasmic reticulum, (ii) parietal chloroplasts, and (iii) a median vacuolar region surrounded by several Golgi bodies and diverse vesicles. Associated with the emergent flagellum is a “paraflagellar complex” that consists of dense globules, cross‐striated ribbon‐like structures, a paraflagellar body, and an array of parallel striated filaments. The stigma consists of a single layer of pigmented granules that partially surrounds the canal/reservoir transition zone where microtubular bands intersect. A microtubular cytoskeleton consists of pellicular microtubules, peri‐canal microtubules, stigma‐associated microtubules and para‐reservoir microtubules. The thickenings on the posterior, concave margins of the pellicular strips suggest that this pellicle is of intermediate complexity between those of Euglena spirogyra (Ehrenb. and Trachelomonas volvocina (Ehrenb.).
ULTRASTRUCTURE OF CELL DIVISION AND REPRODUCTIVE DIFFERENTIATION OF MALE PLANTS IN THE FLORIDEOPHYCEAE (RHODOPHYTA): CELL DIVISION IN POLYSIPHONIA1
Authors: Scott Joe , Cynthia Bosco , Schornstein Kathleen , Thomas Jewel 
Published: August 2007

ABSTRACTCell division in the marine red algae Polysiphonia harveyi Bailey and P. denudata (Dillwyn) Kutzing was studied with the electron microscope. Cells comprising the compact spermatangial branches of male plants were used exclusively because of their small size, large numbers and the ease with which the division planes can be predetermined. Some features characterizing mitosis in Polysiphonia confirm earlier electron microscope observations in Membranoptera, the only other florideophycean algae in which mitosis has been studied in detail. Common to both genera are a closed, fenestrated spindle, perinuclear endoplasmic reticulum, a typical metaphase plate arrangement of chromosomes, conspicuous, layered kinetochores, chromosomal and non‐chromosomal microtubules, and nucleus associated organelles (NAOs) known as polar rings (PRs) located singly in large ribosome‐free zones of exclusion at division poles in late prophase. However, other features, unreported in Membranoptera, were observed consistently in Polysiphonia. These include the presence of PR pairs in interphase‐early prophase cells, the attachment of PRs to the nuclear envelope during all mitotic stages, the migration of a single PR to establish the division axis, a prominent, nuclear envelope protrusion (NEP) at both division poles at late prophase, the prometaphase splitting of PRs into proximal and distal portions, and the reformation of post‐mitotic nuclei by the separation of an elongated interzonal nuclear midpiece at telophase. During cytokinesis, cleavage furrows impinge upon a central vacuolar region located between the two nuclei and eventually pit connections are formed in a manner basically similar to that reported for other red algae. Diagrammatic sequences of proposed PR behavior during mitosis are presented which can account for events known to occur during cell division in Polysiphonia. Mitosis is compared with that reported in several other lower plants and it is suggested that features of cell division are useful criteria to aid in the assessment of phylogenetic relationships of red algae.
THE GLYCEROL PERMEABILITY OF THE PLASMALEMMA OF THE HALOTOLERANT GREEN ALGADUNALIELLA PARVA(VOLVOCALES)1
Authors: Enhuber Gerhard , Gimmler Hartmut 
Published: August 2007

ABSTRACTThe glycerol permeability of the plasmalemma of the green algaDunaliella parvaLerche was investigated by efflux studies with labelled glycerol, by enzymatic determination of glycerol leakage, and the determination of the reflection coefficient from osmotically induced volume changes (zero flow method).All results indicate that the plasmalemma ofD. parvadoes not exhibit a special low permeability towards glycerol as would be expected from a glycerol accumulating alga. Rather, significant amounts of glycerol diffuse continuously into the medium following the glycerol concentration gradient between the cells and the medium. Efflux rates vary between 0.1 and 2 μmoles glycerol·mg−1chlorophyll·h−1depending on the external NaCl concentration. After one day up to 25% of the total glycerol of the algal suspension was found in the medium. Within 10 days this value can increase to 60%, depending on the growth constant of the culture. The reflection coefficient σ was determined to be 0.87, the permeability coefficient 2800×10−11m·sec−1.To maintain a proper endogenous glycerol level corresponding to the external osmotic pressure, glycerol efflux inD. parvahas to be balanced by a continuous synthesis of glycerol.D. parvafollows the strategy of “glycerol efflux tolerance” instead of “glycerol efflux avoidance”. The alga has to pay the energetic costs of this strategy of tolerance.
PILINIA EARLEAE N. SP. (CHLOROPHYCEAE, CHROOLEPIDACEAE) FROM THE FLORIDA WEST COAST1
Authors: Gallagher Susan B. , Humm Harold J. 
Published: August 2007

ABSTRACT Pilinia earleae n. sp. family Chroolepidaceae, was found in the Tampa Bay area of the Florida west coast in October, 1976, on the tunic of an ascidian, later on dead mollusc shells, a nylon faking line, plastic strips, and as an epiphyte of Gracilaria foliifera, a red alga. It is described on the basis of abundant material from the natural environment and laboratory cultures. The type locality is the southernmost known for the genus in the western North Atlantic.
CULTURING MICROSCOPIC STAGES OF MACROCYSTIS PYRIFERA (PHAEOPHYTA) IN AQUIL, A CHEMICALLY DEFINED MEDIUM1
Authors: Kuwabara James S. , North Wheeler J. 
Published: August 2007

ABSTRACTRequirements of Macrocystis pyrifera (L.) C. A. Agardh (giant kelp) for nine nutrient elements (N, P, Mn, Fe, Co, Cu, Zn, Mo, I) were established by batch culturing settled spores, through the gametophytic phase, to production of embryonic sporophytes in Aquil, a chemically defined, artificial seawater medium. The ultimately successful medium resulted from ten sequential culturing series, applying an optimization technique to improve each succeeding formulation.
OBSERVATIONS ON MARINE CHAETOPHORACEAE (CHLOROPHYTA). I. SPORANGIAL ONTOGENY IN THE TYPE SPECIES OF ENTOCLADIA AND PHAEOPHILA1
Authors: O'Kelly Charles J. , Yarish Charles 
Published: August 2007

ABSTRACTA light‐ and electron‐microscope study of sporangial ontogeny in synchronized, mitospore‐producing cultures of Entocladia viridis Reinke, and Phaeophila dendroides (Crouan frat.) Ratters demonstrates that each species has its own characteristic pattern of sporangial development. E. viridis undergoes a sequential cleavage of sporangial mother cell contents with cytokinesis always promptly following mitosis, thus no multinucleate cells are produced. No vesicle surrounds the mature spores, which are released by abrupt rupture of the exit papilla. In P. dendroides a simultaneous cleavage of the sporangial mother cell occurs after a series of synchronous mitoses that result in the production of a multinucleate cell. No vesicle surrounds the mature spores, but a membranous inclusion derived from the central vacuole of the sporangial mother cell lines the sporangial neck at maturity. The inclusion is extruded as a hyaline “plug” through the apex of the sporangial neck some time before release of the spores. This information argues for the retention of the two genera Entocladia and Phaeophila, and suggests another means of deducing higher taxonomic relationships among the marine Chaetophoraceae.
THE CRYPTOMONAD NUCLEOMORPH: ITS ULTRASTRUCTURE AND EVOLUTIONARY SIGNIFICANCE1
Authors: Gillott Marcelle A. , Gibbs Sarah P. 
Published: August 2007

ABSTRACTThe Cryptophyceae are a class of phytoflagellates with affinities to both the red algae and the Chromophyta, by virtue of their possession of both phycobilns and chlorophyllc.Unlike other chromophytes, the periplastidal compartment (the space between the chloroplast envelope and chloroplast ER) is extensive, containing starch grains, ribosomes and a nucleomorph in addition to the vesicles and tubules observed in other chloroplast ER‐containing algae. We have examined the nucleomorph in six species of cryptomonads. There is one nucleomorph per cell except during division, when two are present. The position of the nucleomorph in the interphase cell is species specific: in some species it is embedded in an invagination of the pyrenoid and in others it lies along the inner surface of the chloroplast. The nucleomorph is enclosed by a double membrane; this envelope is interrupted by pores which, in tangential section, appear as elongated slits and have a central dense element. Two types of inclusions have been observed in nucleomorphs: dense globules which are occasionally joined to form ribbons, and a larger fibrillogranular body which resembles a nucleolus. Using a uranyl acetate‐ EDTA‐lead stain, we have tentatively localized nucleic acid within the nucleomorph. The nucleus‐like characteristics of this organelle support the theory that the chloroplast and associated structures bounded by the chloroplast ER represent a reduced eukaryotic endosymbiont. Based on the location of the α‐1,4‐glucan storage product and the presence of phycobilins, we postulate that the endosymbiont was probably a red alga. Other chloroplast ER‐containing algae may have evolved from a cryptomonad‐like ancestor through further reduction of the endosymbiont.
MECHANISMS OF RAPID PHOTOSYNTHETIC ADAPTATION IN NATURAL PHYTOPLANKTON COMMUNITIES. II. CHANGES IN PHOTOCHEMICAL CAPACITY AS MEASURED BY DCMU‐INDUCED CHLOROPHYLL FLUORESCENCE1
Authors: Vincent Warwick F. 
Published: August 2007

ABSTRACTPhotochemical responses to changing light or nutrient conditions were examined in three phytoplankton communities by in vivo chlorophyll fluorescence before (Fa) and after (Fb) the addition of the electron flow inhibitor 3(3,4‐dichlorophenyl)‐1,1‐dimethyl urea. These values were used to calculate an index called “cellular fluorescence capacity” (CFC), defined as (Fb– Fa)/Fb. CFC varied markedly throughout the day and night in the spring community of diatoms and green algae in Lake Taupo, New Zealand. Morning and afternoon maxima were separated by a pronounced depression during the midday peak irradiance. Under continuous low light Taupo plankton demonstrated a circadian rhythm in CFC, but the amplitude of variation was much lower than that recorded under natural or controlled light/dark regimes. In an oligotrophic water body (Wastwater) in the English Lake District a bimodal relationship between CFC and depth was observed when surface features indicated Langmuir circulation. Photochemical capacity measured as CFC could be raised or lowered in samples from this lake by exposure to bright or dim light for 4–8 h. Phytoplankton from a eutrophic lake with a history of nitrogen limitation (Lake Rotorua, New Zealand) responded to nitrogen enrichment after a lag of 4–6 h by an increase in CFC. This was correlated with enhanced rates of carbon fixation and, at longer time intervals, increased growth rates. These CFC data are consistent with the hypothesis that the capacity for non‐cyclic electron transport in natural phytoplankton communities is highly responsive to short‐term changes in light or the availability of nutrients.