bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEXUAL PROCESSES IN THE LIFE CYCLE OFGYRODINIUM UNCATENUM(DINOPHYCEAE): A MORPHOGENETIC OVERVIEW1
Authors: Coats D. Wayne , Tyler Mary A. , Anderson Donald M. 
Published: November 2004

ABSTRACTSexual processes in the life cycle of the dinoflagellateGyrodinium uncatenumHulburt were investigated in isolated field populations. Morphological and morphogenetic aspects of gamete production, planozygote formation, encystment, excystment, and planomeiocyte division are described from observations of living specimens, Protargol silver impregnated material and scanning electron microscope preparations. The sexual cycle was initiated by gamete formation which involved two asexual divisions of the vegetative organism. Gametes were fully differentiated following the second division and immediately capable of forming pairs. Either isogamous or anisogamous pairs were formed by the mid‐ventral union of gametes. Gametes invariably joined with flagellar bases in close juxtaposition. Complete fusion of gametes required ca. 1 h, involved plasmogamy followed by karyogamy and resulted in a quadriflagellated planozygote. Planozygotes encysted in 24–48 h to yield a hypnozygote capable of overwintering in estuarine sediments. Hypnozygotes collected from sediment in late winter readily excysted upon exposure to temperatures above 15°C. A single quadriflagellated planomeiocyte emerged from the cyst and under culture conditions divided one to two days later. The four flagella were not evenly distributed at the first division and both bi‐ and tri‐flagellated daughter cells were formed.
LIFE HISTORIES OFBLIDINGIA MINIMA(CHLOROPHYCEAE), ESPECIALLY SEXUAL REPRODUCTION1
Authors: Tatewaki Masakazu , Lima Masafumi 
Published: November 2004

ABSTRACTBlidingia minima(Näg. ex Kütz.) Kylin from Muroran, Hokkaido, Japan, has been shown to exhibit four patterns of life history in culture. Sexual reproduction, reported fully for the first time in the genus, occurs in two of them. I. An isomorphic‐heteromorphic complex in which erect, tubular sporophytes alternate with dioecious gametophytes of the same forms, with the irregular production by both phases of discoid or pulvinate (pincushion‐like) microthalli capable of both sexual and asexual reproduction. II. An alternation of heteromorphic phases in which an erect, tubular sporophyte alternated irregularly with a gametophytic microthallus. III. An asexual alternation of heteromorphic phases in which an erect, tubular frond alternates irregularly with a microthallus by means of quadriflagellate zoospores. IV. An asexual, monophasic life cycle in which erect, tubular fronds are perpetuated by quadriflagellate zoospores. The first pattern occurred in spring populations from one of three sites. The second occurred in populations from two sites. The third and fourth occurred in all populations tested. The life history ofBlidingia minimafrom Muroran is similar to that ofKornmannia zostericolafrom Muroran.
VARIABILITY OF CELL WALL STRUCTURE AND HYDROCARBON TYPE IN DIFFERENT STRAINS OF BOTRYOCOCCUS BRAUNII1
Authors: Berkaloff Claire , Rousseau Bernard , Couté Alain , Casadevall Eliette , Metzger Pierre , Chirac Christian 
Published: November 2004

ABSTRACTDifferent samples of Botryococcus braunii Kütz., freshly collected from nature or laboratory‐grown from culture collection strains, were studied by electron microscopy and their hydrocarbon content analyzed. Although the general internal structure of the cells was rather constant, the organization of the outer walls forming the hydrocarbon‐rich matrix of the colonies differed greatly from one sample to another. In the majority of cultivated strains, the colonies were rather small, the different successive external walls remained distinct and all strains contained dienic or trienic hydrocarbons. In contrast, most of the collected samples possessed large colonies with a rather compact matrix formed by the hydrocarbon‐rich part of the successive closely appressed external wall layers. These samples contained polyunsaturated hydrocarbons, i.e. botryococcenes. Well defined cell caps which sheared off the cells were observed only in those strains with a compact matrix. The Austin strain and some collected samples, however, were intermediate with rather small colonies, dense matrix, definite cell caps and dienic hydrocarbons. Thus, the hydrocarbon composition did not correlate directly with the variations in wall structure; however, the occurence of dienic and botryococcene‐like hydrocarbons together in one strain was never observed, although analyzed at various stages of growth. Thus, the existence of distinct strains of Botryococcus braunii, some synthesizing dienes, others botryococcenes, appears highly probable.
PHOSPHORUS AND THE GROWTH OF JUVENILE MACROCYSTIS PYRIFERA (PHAEOPHYTA) SPOROPHYTES1
Authors: Manley Steven L. , North Wheeler J. 
Published: November 2004

ABSTRACTThe effect of phosphate (Pi) supply on growth rate and tissue phosphorus content of juvenile Macrocystis pyrifera (L.) C. Ag. sporophytes was examined. Sporophytes were batch cultured in aquaria with flowing recirculated seawater enriched by 30 μM nitrate. Each aquarium was supplemented with a different seawater Pi concentration, 0, 0.3, 1, 2, 3, and 6 μM. Sporophyte mean specific growth rates declined with time in all cultures presumably due to the normal developmental decrease in the proportion of meristematic tissue of each plant. Growth rate declines were more pronounced in cultures that were nutrient limited. Sporophyte growth was P‐limited after two‐week exposure to Pi less than 1 μM, corresponding to a tissue P concentration of less than 0.20% dry weight. Plants cultured at 6 μM Pi contained tissue P levels of 0.53% dry weight after three weeks. Luxury consumption and storage of P occurred.
INTERSPECIFIC VARIATION IN DARK NITROGEN UPTAKE BY DINOFLAGELLATES1
Authors: Paasche Eystein , Bryceson Ian , Tangen Karl 
Published: November 2004

ABSTRACTSeven species of marine dinoflagellates were grown in nitrogen‐sufficient media under a 12:12 h L:D cycle, and then tested for their ability to take up nitrate and ammonium in the light and in the dark in short‐term experiments with 15N‐labelled substrate. The effect of the N substrate chosen, and the effect of sampling time in the L:D cycle, on the relative nitrogen content (the C:N ratio) was investigated at the same time. The physiological extremes in the material were represented by Prorocentrum minimum (Pav.) J. Schiller, which took up and presumably assimilated nitrate equally fast in the light and in the dark, and Gyrodinium aureolum Hulburt, which did not take up nitrate in the dark when in a state of nitrogen sufficiency. A strong coupling between nitrate assimilation and photosynthetic carbon assimilation in the latter species was suggested by the close similarity of the light saturation curves of 15NO3− and 14CO2 incorporation, and by a complete blocking of 15NO3− incorporation by 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU). Nitrogen starvation for 24 h induced a capacity in G. aureolum for taking up nitrate in the dark, or in the light in the presence of DCMU, a phenomenon that might be useful for identifying nitrogen limitation in this species in the field. Our study emphasizes the variability of dinoflagellate nitrogen nutrition and illustrates the difficulty of associating mass occurrences of dinoflagellates in nature with any particular nutritional mode.
REPRODUCTION AND LIFE HISTORY OF THE RED ALGA GALAXAURA OBLONGATA (NEMALIALES, GALAXAURACEAE)1
Authors: Magruder William H. 
Published: November 2004

ABSTRACTCulture and morphological studies showed that Galaxaura oblongata (Ellis et Solander) Lamouroux has a triphasic life history with conspicuous gametophytes and small filamentous tetrasporophytes. Development of male and female reproductive structures is very similar and both begin with the enlargement of a terminal cell of a filament branch occupying a normal vegetative position within the apical pit of a thallus branch. In male thalli this modified branch forms a conceptacle in which spermatangia are produced. In female thalli, this modified branch forms a three‐celled carpogonial branch consisting of a carpogonium, hypogynous cell and basal cell. Filament branches from the basal cell form a pericarp and the gonimoblast develops directly from the carpogonium. Carposporangia are produced in conceptacles which resemble the male conceptacles. About the time the first carposporangia are produced, the carpogonium, hypogynous cell and basal cell form a large fusion cell. Released carpospores germinate in a unipolar or bipolar manner and form small filamentous thalli. Under short day conditions, cruciate tetrasporangia are produced in small clusters. Tetraspores germinate similarly to carpospores and also form small filamentous thalli. Under low nutrient conditions, small cylindrical thalli develop on the filaments and these appear similar to gametophytes collected in nature.
SEXUALITY AND CYST FORMATION IN THE DINOFLAGELLATEGONYAULAX TAMARENSIS:CYST YIELD IN BATCH CULTURES1
Authors: Anderson Donald M. , Kulis David M. , Binder Brian J. 
Published: November 2004

ABSTRACTEncystment of the toxic dinoflagellateGonyaulax tamarensisLebour (var.excavata) was monitored in batch cultures exposed to a variety of nutritional and environmental treatments. Limitation by nitrogen (as ammonium or nitrate) or phosphorus (as phosphate) resulted in cyst formation. When the initial concentration of limiting nutrient was varied, total cyst yield (mL−1) was directly proportional to the cell yield at all but the highest nutrient concentrations (where encystment was minimal). Encystment efficiency was relatively constant (0.1–0.2 cysts · cell−1) over a 5‐fold range of cell densities, indicating that 20 to 40% of the vegetative populations successfully encysted. Cyst formation was negligible in nutrient‐replete medium, even with a significant reduction in growth rate due to non‐optimal light, temperature, or to high batch culture cell densities. Low light levels did decrease cyst yield once encystment was initiated by nutrient limitation, but this was probably linked to smaller motile cell yield and not to a specific inhibition of encystment. In contrast, encystment was more sensitive to temperature than was growth rate: optimal cyst production occurred over a relatively narrow temperature range and no cysts were formed at [Page missing]
DIURNAL MOVEMENTS OF METALIMNETIC PHYTOPLANKTON1
Authors: Pick F. R. , Lean D. R. S. 
Published: November 2004

ABSTRACTA metalimnetic population of the colonial chysophyteChrysosphaerella longispinaLauterborn was observed using in vivo fluorometry to undergo a 1.5 m diurnal migration through a 5° C temperature gradient over four summers in a mesotrophic lake on the edge of the Canadian Shield. The population was highest in the water column at midday and early afternoon. The minimum depth reached during the day by the population was best correlated with the mean irradiance of the day of the observation plus that for the previous day. Rarely did the population cross the thermocline. Estimates of the migrational velocity determined by in vivo fluorometry were higher (maximum rate of 10.8 m·d−1) than estimates obtained with in situ settling chambers (maximum rate of 0.43 m·d−1); however the pattern of migration obtained by both methods was similar. The migratory ability of this alga appeared to provide little advantage in nutrient uptake.Oscillatoria agardhiiGomont, which comprised only 5% of the total algal biomass in the metalimnion, did not undergo pronounced diurnal migrations in the chambers and was positively buoyant over 24 h.
ALGAE FROM CABO FRIO UPWELLING AREA. 2. GELIDIOCOLAX PUSTULATA (GELIDIACEAE, RHODOPHYTA): AN UNUSUAL NEW PUTATIVE PARASITIC SPECIES1
Authors: Yoneshigue Yocie , de Oliveira Eurico C. 
Published: November 2004

ABSTRACTA new species of Gelidiocolax Gardner, G. pustulata Oliveira and Yoneshigue, is described in the tropical western Atlantic from Brazil. The species usually grows on the basal portion of the main axis of Pterocladia capillacea (Gmelin) Bornet et Thuret. Abundant material was collected mainly from November to March at Cabo Frio Island, in the northeast part of the State of Rio de Janeiro, a marine area well known for its upwelling. Infection by the putative parasite seems to damage the host tissue, stimulating the development of a “gall‐like” structure that leads to the outgrowth of adventitious branches. The new species has the vegetative features and reproductive structures of the genus Gelidiocolax. It can be distinguished from the other Gelidiocolax species mainly on the basis of its position on the host, size of pustula, the tetrasporangia and the development of spermatangia. Studies of this new taxon support the placement of Gelidiocolax in the Gelidiaceae and not the Choreocolacaceae, as has been suggested in the literature.
MITOSIS AND CELL DIVISION IN HYDRURUS FOETIDUS (CHRYSOPHYCEAE)1
Authors: Vesk Maret , Hoffman Larry R. , Pickett‐Heaps Jeremy D. 
Published: November 2004

ABSTRACTMitosis and cell division have been examined ultrastructurally in the vegetative cells of Hydrurus foetidus (Vill) Trev. and found to resemble that of Ochromonas in two important aspects. First, the rhizoplast acts as the spindle organizing body and second, the spindle elongates considerably during anaphase. It differs from Ochromonas in that there is no movement of the basal bodies and flagella towards the poles. Moreover, the nuclear envelope remains relatively intact throughout early stages of mitosis, with gaps developing at the poles during prophase to permit entry of spindle microtubules. Disruption of the nuclear envelope does not occur in the equatorial plane until late anaphase. The spindle persists into telophase and is bent towards the posterior of the cell by the ingrowing edge of the cleavage furrow. Persistence of the spindle and lack of Ochromoms‐type cell elongation may be related to the constricting presence of the sheath during cell division—a completely different strategy to that adopted by the green algae under conditions of similar constraint.
CRITICAL IRRADIANCE LEVELS AND THE INTERACTIVE EFFECTS OF QUANTUM IRRADIANCE AND DOSE ON GAMETOGENESIS IN THE GIANT KELP, MACROCYSTIS PYRIFERA1
Authors: Deysher Lawrence E. , Dean Thomas A. 
Published: November 2004

ABSTRACTGametophytes of Macrocystis pyrifera (L.) C. Ag. were cultured under a series of quantum irradiances in three photoperiod regimes. The quantum irradiances in each photoperiod were adjusted to provide equal daily irradiation dosages between photoperiods which allowed a critical examination of the interactions between quantum irradiance and quantum dose in determining gametophyte fertility. The lowest quantum irradiance which stimulated gametogenesis in more than 50% of the female gametophytes was 5 μE·m−2·s−1. The saturating irradiance was ca. 10 μE·m−2·s−1 at photoperiods of 12 h or greater. In terms of daily quantum dose, the lowest dose at which greater than 50% gametogenesis occurred was 0.2 E·m−2·d−1. However, this critical quantum dose was higher (0.4 E·m−2·d−1) when instantaneous irradiances were less than 5 μE·m−2·s−1. The saturation quantum dose was also affected by the rate at which the quantum dose was received and varied from 0.4 to 0.8 E·m−2·d−1. Gametophytes in all three photoperiods reached 100% fertility at quantum irradiances above 5 μE·m−2·s−1. Photoperiod effects were small and could be accounted for by quantum dosage effects.
PURIFICATION AND PROPERTIES OF THE MUCUS OFEUGLENA GRACILIS(EUGLENOPHYCEAE)1
Authors: Cogburn J. Nita , Schiff Jerome A. 
Published: November 2004

ABSTRACTAnionic groups were demonstrated in the mucus ofEuglena gracilisKlebs var.bacillarisCori by histochemical staining with alcian blue or diaminobenzidine tetrahydrochloride and were quantified during the growth cycle with an alcian blue dye‐binding assay. Mucus in the culture increased during growth and became high when the culture entered the stationary phase. Cultures were grown under conditions which uniformly labeled all sulfur containing compounds with35S. A purification scheme was devised using 0.15 M NaCl and 0.10 M EDTA at pH 8 (Marmur's solution) to separate the mucus from the cells without cell breakage. The isolated purified mucus was fractionated with sodium dodecyl sulfate (SDS) at 100° C into soluble and insoluble components. The soluble fraction was separated by SDS polyacrylamide gel electrophoresis into 18 polypeptide bands ranging from 22 to 320 kdaltons that stained with Coomassie blue; 16 of these bands also stained for carbohydrates using periodic acid‐Schiffs reagent, indicating their glycoprotein nature. On hydrolysis, the SDS soluble fraction yielded xylose, fucose, rhamnose, and hexose. The SDS insoluble fraction contained no35S label, and, therefore, presumably no protein or bound sulfate; this gelatinous material does not contain the same sugar residues as the glycoproteins in the SDS soluble fraction. Its staining properties with alcian blue and its resistance to hydrolysis suggested the presence of uronic acids. Comparison with otherEuglenafractions showed that bands comigrating with the mucus glycoproteins were not detectable in the fractions containing the whole cells or the culture medium. Although the mucus ofEuglenayielded appreciable sulfate during mild acid treatment, most if not all of this sulfate appears to have come from the oxidation of reduced sulfur rather than from the hydrolysis of covalently bound sulfate. An infrared spectrum of the mucus showed only minor peaks in the correct regions for the S‐O linkage. Thus, the mucus ofEuglenais composed of glycoproteins and polysaccharides which contain little or no ester sulfate.
GROWTH AND POLYSACCHARIDE PRODUCTION BY THE GREEN ALGACHLAMYDOMONAS MEXICANA(CHLOROPHYCEAE) ON SOIL1
Authors: Kroen William K. 
Published: November 2004

ABSTRACTThe polysaccharide producing soil algaChlamydomonas mexicanaLewin was grown on soil surfaces in a growth chamber, with cell number and total polysaccharide measured weekly. Cell growth was pronounced, reaching an excess of 107cells · cm−2within one week. Polysaccharide production was also pronounced, with similar amounts of polysaccharide synthesized whether or not the cells were continuously given nutrients. Polysaccharide synthesis increased once the cells slowed in their growth, as in previous work with the cells in liquid medium.
A SIMPLE METHOD FOR THE ISOLATION AND ENUMERATION OF SPARSE POPULATIONS OF CYANOBACTERIA IN ESTUARINE WATERS1
Authors: Huber Ann L. 
Published: November 2004

ABSTRACTA simple, sensitive assay method for the isolation and enumeration of sparse populations of cyanobacteria in an estuarine system is described. The method, based on the standard membrane‐filter plate count technique, differentiates between viable and nonviable cells. It was found that an estuarine water‐based agar medium was the most suitable medium for isolation of cyanobacteria. Because of the restricted nature of colony development, isolation of individual species is easily accomplished.
A transmembrane protein–tyrosine phosphatase receptor type C (CD45) exon A point mutation (77 C to G) is not associated with the development of type 1 diabetes mellitus in a German population
Authors: Thude H. , Rosenhahn S. , Hunger‐Dathe W. , Müller U.‐A. , Barz D. 
Published: November 2004

SummaryTo investigate whether a C to G transversion at position 77 in exon A of the CD45 gene is associated with the development of diabetes mellitus type 1 (T1D), we studied 165 patients and 220 control individuals. The frequency of the 77G allele in the control group was 1.1%, which was not significantly different from the 1.2% found in the patient group (P = 0.922). The C to G transversion does not seem to be associated with susceptibility for T1D.
Plant‐mediated methane emission from an Indian mangrove
Authors: Purvaja Ramachandran , Ramesh Ramachandran , Frenzel Peter 
Published: November 2004

AbstractMangroves have been considered for a long time to be a minor methane source, but recent reports have shown that polluted mangroves may emit substantial amounts of methane. In an unpolluted Indian mangrove, we measured annual methane emission rates of 10 g CH4 yr−1 from the stands of Avicennia marina. This rate is of the same order of magnitude as rates from Northern wetlands. Methane emission from a freshwater‐influenced area was higher, but was lower from a stunted mangrove growing on a hypersaline soil. Methane emission was mediated by the pneumatophores of Avicennia. This was consistent with the methane concentration in the aerenchyma, which decreased on average from 350 ppmv in the cable roots to 10 ppmv in the emergent part of the pneumatophores. However, the number of pneumatophores varied seasonally. The minimum number occurred during the monsoon season, which reduced methane emissions largely. Ebullition from unvegetated areas may also be important, at least during monsoon season when measured bubble fluxes were occasionally about five times as high as pneumatophore‐mediated emissions.
Soil acidification induced by elevated atmospheric CO2
Authors: Oh Neung‐Hwan , Richter Daniel D. 
Published: November 2004

AbstractSoil acidification is a very important process in the functioning of earth's ecosystems. A major source of soil acidity is CO2, derived from the respiration of plant roots and microbes, which forms carbonic acid in soil waters. Because elevated atmospheric CO2often stimulates respiration of soil biota in experiments that test ecosystem effects of elevated atmospheric CO2, we hypothesize that rising atmospheric CO2(which has increased from ∼200 ppm since the interglacial and may exceed 550 ppm by the end of the 21st century) is significantly increasing acid inputs to soils. Here, using column‐leaching experiments with contrasting soils, we demonstrate that soil CO2is a much more potent agent of soil acidification than is generally appreciated, capable of displacing almost all exchangeable base cations in soils, and even elevating Al(III) concentrations in H2CO3‐acidified soil waters. The potent soil acidifying potential of soil H2CO3is attributed to the low pKa,1of molecular H2CO3(3.76 at 25°C), which contrasts greatly with that of(a convention that combines CO2(aq) and molecular H2CO3, the pKa,1of which is 6.36 at 25°C). This distinction is significant for soil systems because of soil's greatly elevated CO2, their variety of sinks for H+, and the wide range of contact times between soil solids, water, and gas. Modelling suggests that a doubling of atmospheric CO2may increase acid inputs from carbonic acid leaching by up to 50%. Combined with the results of CO2studies in whole ecosystems, this implies that increases in atmospheric CO2since the interglacial have gradually acidified soils, especially poorly buffered soils, throughout the world.