bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NEW HOMOTHALLIC VARIETY OF CHLAMYDOMONAS MOEWUSH (CHLOROPHYCEAE)1
Authors: Deason Temd R. , Ratnasabapathy M. 
Published: August 2007

SUMMARYA new homothallic variety of Chlamydomonas moewusii Gerloff var. monoica is described. When first isolated, the alga exhibited a very strong mating reaction (80–90% zygotes on 2 wk BBM agar slants), but after 2 mo in axenic culture, the reaction was significantly reduced in intensity. Attempts were made to restore the initial mating intensity by varying environmental conditions, but met with limited success. The alga did not grow heterotrophically in carbon‐supplemented BBM medium.
EFFECT OF THE SINKING RATE OF TWO DIATOMS (THALASSIOSIRA SPP.) ON UPTAKE FROM LOW CONCENTRATIONS OF PHOSPHATE1
Authors: Canelli Edmondo , Fuhs G. Wolfgang 
Published: August 2007

SUMMARYThe effect of the sinking rate, or rate of medium flow (φ) on the rate of phosphate incorporation (V) by the planktonic diatoms Thalassiosira fluviatilis Hust. and T. pseudonana Hasle & Heimdal in batch and chemostat cultures was determined by passing medium at defined flow rates (0.5–25.0 mm·min−1) over algae on membrane filters. At concentrations from 1 to 100 μg phosphorus·l−1 V, increases with increasing velocity of flow, approaching a maximum value (Vm) as described by the empirical relationship:
image

where Kφ is the sinking rate value when V = 1/2 Vm+ Vo and Vo is the uptake at 0 rate of flow. By comparing uptake at controlled flow with uptake in a vigorously stirred medium, the phosphate concentration in the cell boundary layer can be determined. The sinking rate that reduces the phosphate concentration in the boundary layer to half of nominal concentration in the medium is much lower for the larger T. fluviatilis than for T. pseudonana. For both diatoms, it is inversely related to the nominal concentration.
SPORELING COALESCENCE IN CHONDRUS CRISPUS (RHODOPHYCEAE)1
Authors: Tveter Eleanor , Mathieson Arthur C. 
Published: August 2007

SUMMARYCoalescence of developing sporelings of Chondrus crispus Stackhouse was observed. Juvenile tetra‐sporophytes showed a higher proportion of coalescence than developing gametophytes. Stages of complete coalescence between different sporelings are illustrated. Coalesced sporelings exhibit vertical and horizontal alignment of cells, as well as “cuticular” continuity and secondary pit connections between adjacent, coalesced sporelings. Ultimately the cells in the center of the coalesced sporelings produce upright, multiaxial fronds that grow more rapidly than fronds of non‐coalesced sporelings. Other red algae, such as Gracilaria verrucosa (Hudson) Papenfuss and Gigartina stellata (Stackhouse) Batters also show a similar sequence of sporeling coalescence and enhanced growth. The ecological significance of sporeling coalescence is discussed.
ECOLOGY AND NATURAL HISTORY OF IRIDAEA CORDATA (RHODOPHYTA; GIGARTINACEAE): POPULATION STRUCTURE1
Authors: Hansen Judith E. , Doyle William T. 
Published: August 2007

SUMMARYThe population structure of 4 California Iridaea cordata (Turner) Bory populations was studied. Random sampling procedures were used to measure seasonal variations in standing crops, density and size‐class distribution of life history stages. The results describe aspects of the in situ life history; a prerequisite to realistically considering the distribution, ecology or life history expressions of an alga. Seasonal fluctuations in density occur only in the juvenile stage, which is initiated during the winter (November to January) predominantly from the basal perennial crusts. Both the gametangial and tetrasporangial stages are present throughout the year. The tetrasporangial stage is dominant in relation to the sexual stages in both density and biomass during most of the year, except spring when the new crop in just maturing and all stages are abundant. Density in nearly constant and observable changes in the populations are due to biomass fluctuations. Seasonal lows in biomass occur during the winter with the majority of thalli in the smaller size‐classes. Growth and maturation culminate in peak summer crops and dominance of the tetrasporangial stage, followed by autumnal senescence and die‐back in winter. Carrageenans analyzed from immature thalli showed a predominance of lambda‐type, previously determined as specific for tetrasporangial plants. This indirect evidence for the tetrasporangial nature of immature plants suggests that dominance of the diploid stage occurred prior to blade development and most likely at the spore level. Alternatively, field results indicate a major contribution and possible replacement of alternation of gametangial and tetrasporangial stage by thallus perennation and vegetative reproduction.
THE OCCURRENCE OF CHLOROPHYLL C1 AND C2 IN ALGAE1
Authors: Jeffrey S. W. 
Published: August 2007

SUMMARYForty‐two species of chlorophyll c‐containing algae (diatoms, dinoflagellates, chrysomonads, haptophytes, cryptomonads and xanthophytes) were examined for their content of chlorophyll c1 and c2. This work, and recent studies on c1/c2 distribution in the literature (total 86 species), show that chlorophyll c2 is universal to all algae examined. Chlorophyll c1 occurs in addition to c2 in brown seaweeds, diatoms, chrysomonads, haptophytes (coccolithophorids) xanthophytes and the, fucoxanthin‐containing dinoflagellates; c2 only occurs in dinoflagellates and cryptomonads. Two exceptions to the generalizations are one dinoflagellate and one cryptomonad containing c1 in addition to c2 No explanation can be offered on present knowledge for these exceptions. No alga was found containing only chlorophyll c1.Chlorophyll c, far from being a minor accessory chlorophyll, occurred in amounts almost equal to chlorophyll a(some diatoms and dinoflagellates) or ranged from 50 to 20% of the chlorophyll a (diatoms, dinoflagellates, chrysomonads, cryptomonads, browns). Xanthophytes, however, contained only trace amounts of chlorophyll c with ratios of chlorophyll a:c ranging from 55:1 to 116:1 on a weight basis.In those algae with both chlorophyll c components, c1 and c2, occurred either in equal amounts, or chlorophyll c2was twice the c1 content.
AUXIN, AN ENDOGENOUS REGULATOR OF GROWTH IN ALGAE?1,2
Authors: Buggeln Richard G. 
Published: August 2007

SUMMARYThe effects of 5 pairs of synthetic auxins and chemically related, but biologically inactive, derivatives (e.g., 2,4‐ and 3,5‐dichlorophenoxyacetic acid, respectively) on blade growth of the brown alga, Alaria esculenta (L.) Grev.(Laminariales) were studied. The significant result was the inability to divide the growth responses into auxin and non‐auxin groups. At high concentrations (10−3 M) 9 test substances inhibited blade growth; lower concentrations (<10−3 M) were either slightly inhibitory or showed no effect.The data suggest that a higher plant auxin‐specific recognition mechanism is lacking in this alga. As this mechanism is central to higher plant concepts of growth control by auxin, the role of auxin as an endogenous regulator of growth in Alaria, and perhaps other algae as well, seems unlikely. This interpretation is consistent with recent negative biochemical data from auxin binding studies using subcellular preparations from algae.
LEAD INHIBITION OF CHLOROPHYCEAN MICROALGAE1
Authors: Monahan Thomas J. 
Published: August 2007

SUMMARYThe effects of lead on the growth of 9 microalgae representing 4 chlorophycean genera were investigated in axenic laboratory cultures. Variations in sensitivity to lead existed among the algae tested with availability of phosphate often limiting growth. Under conditions in which phosphate was growth limiting at pH 6.2, Chlorella pyrenoidosa Chick, C. ellipsoidea Gerneck, C. vulgaris Beij. Scenedesmus sp. (IUCC 1591).Sc. Obtusiusculus Chodat and Selenastrum capricornutum Printz first showed toxicity at 0.5 mg·l−1 pb. Two planktonic Scenedesmus spp. And an Ankistrodesmus sp. Were more tolerant, developing toxicity at 1 mg· l−1 Pb. The relationship of phosphate supply to Pb toxicity was investigated with S. capricornutum and Sc. Obtusiusculus. Al pH 8.0, Selenastrum developed toxicity at 3 mg·l−1 pb either with or without phosphate. When phosphate supply was growth‐limiting, 6 times as much pb (i.e., 3 vs. 0.5 mg l−1 was required to demonstrate toxicity with Selenastrum at pH 8.0 as opposed to pH 6.2 Sc. Obtusiusculus was inhibited at 0.5 mg· l−1 pb in phosphate‐limiting medium and developed toxicity at 1 mg·l−1 in media containing phosphate. Control of colonial morphology with Sc. Obtusiusculus was inhibited. Phosphate availability as well as pH would seem to be important factors determining lead toxicity with some algae.
ALGAL COMPETITION IN AN EPILITHIC RIVER FLORA1
Authors: Klotz Richard Larry , Cain Jerome R. , Trainor Francis R. 
Published: August 2007

SUMMARYField and laboratory procedures demonstrate that the effluent from the Willimantic, Connecticut, sewage treatment plant changes the numerical composition of the dominant epilithic algae in the Shetucket River. This effect is due to the effluent altering the competitive balance between chlorella sp. and Achnanthes deflexa Reim. The chlorella completely dominates highly polluted stretches of the river, and shares dominance with A. deflexa in other areas. The degree of river pollution can be estimated by enumerating the natural standing crops of these 2 algae. A 2‐membered assay utilizing these organisms is a sensitive laboratory pollution monitor and a useful predictive tool. Dominant stands of these epilithic species develop in polluted and unpolluted zones in this river due to competition for the limited area on the cobbles.
AN AUTORADIOGRAPHIC AND HISTOCHEMICAL LOCALIZATION OF SULFATED POLYSACCHARIDES IN EUCHEUMA NUDUM (RHODOPHYTA)1
Authors: La Claire John W. , Dawes Clinton J. 
Published: August 2007

SUMMARYThe predominant sulfated polysaccharide, ˛‐carrageenan, was localized in the middle lamella of epidermal, cortical and medullary cells of Eucheumanudum J. Agardh. Autoradiographic studies with 35SO4= indicated that the label was first incorporated in the inner wall and ultimately deposited in the middle lamella of all cells, and in an outer wall layer of the epidermal cells. There was no evidence for cytoplasmic incorporation of the label. The middle lamella stained with alcian blue, was γ‐metachromatic with toluidina blue O and bound diaminobenzidine‐osmium tetroxide. This region was also positive with periodic acid‐Schiff's (PAS) ragent, possibly demonstrating cellulose and/or a nonsulfated precursor of ˛‐carrageenan.A proposed model for extracellular sulfation includes production and secretion of a nonsulfated polygalactan and sulfotransferase enzyme(s) by the golgi apparatus and endoplasmic reticulum, respectively. Free sulfate in the wall would be bound to the precursor polysaccharide, with much of the resulting carrageenan migrating to the middle lamella facilitating mutual cell growth.
THE RELATIONSHIP BETWEEN PHOTOSYNTHESIS AND LIGHT FOR NATURAL ASSEMBLAGES OF COASTAL MARINE PHYTOPLANKTON1
Authors: Platt Trevor , Jassby Alan D. 
Published: August 2007

SUMMARYIn a series of 188 experiments on the, light‐saturation curve for natural assemblages of phytoplankton at 3 stations in Nova Scotia coastal waters, it was found that both the initial slope (α) of the curve and the assimilation number (PmB) varied about 5‐fold throughout the year. No differences could be detected between stations, but both α and PmB decreased with depth. The mean value of α for all the experiments was 0.21 mg C[mg Chl a]−1· h−1· W−1· m2 with a range from 0.03 to 0.63. An explanation is offered for the nonconstancy of a in terms of the effect of cell‐size and shape on self‐shading. An estimate is made from first principles of the physiological maximum‐attainable value of α. This estimate corresponds, within the limits of experimental error, to the highest values of α observed in the study. It is deduced that on the average the phytoplankton were photosynthesizing at only 44% maximum capacity. The mean value of PmB for all experiments was 4.9 mg C[mg Chl a]−1· h−1, with a range from 0.73 to 24.8. In the matrix of partial correlation coefficients, α and PmB were positively correlated with each other; α was correlated with mean solar radiation averaged over the 3 days prior to the experiment, but uncorrelated with temperature; PmB was correlated strongly with temperature but uncorrelated with recent solar radiation. The results show that PmB could be estimated from α and temperature using an empirical multiple regression equation, independent of depth. It is suggested that α and PmB are both correlated with some other factor not measured in the study, perhaps the mean cell‐size of the populations, or the nutrient status of the cells. The predictability of primary production is discussed in the light of this evidence.
PEDINOMONAS NOCTILUCAE (PRASINOPHYCEAE), THE FLAGELLATE SYMBIOTIC IN NOCTILUCA (DINOPHYCEAE) IN SOUTHEAST ASIA1
Authors: Sweeney Beatrice M. 
Published: August 2007

SUMMARYThe small green flagellate symbiotic in the Noctiluca miliaris Suriray from Southeast Asia has been examined by light and electron microscopy. The flagellate is very similar to Pedinomonas minor Korschikoff. The deeper flagellar depression and the habitat distinguish this species of Pedinomonas from P. minor. It is not a euglenoid as originally proposed, since it contains starch. Characters distinguishing it from Micromonas are described. The new combination Pedinomonas noctilucae (Subrahmanyan) comb, nov. is proposed for this flagellate.
OBSERVATIONS ON CELL DEVELOPMENT INCHLAMYDOMONAS SEGNIS(CHLOROPHYCEAE) AT LOW AND HIGH CARBON DIOXIDE TENSION1
Authors: Badour Samir S. , Tan Cheng K. , Waygood Ernest R. 
Published: August 2007

ABSTRACTSome cell cycle events were compared inChlamydomonas segnisEttl during its development in synchronous cultures (12:12 LD) supplied with air and air enriched with 5% CO2. In cultures bubbled with air, growth resulted in production of 2 relatively small zoospores. In cultures provided with 5% CO2, 4 large zoospores were formed but not released in darkness unless the cultures were bubbled with CO2‐free air and/or exposed to light. Respiration in zoospores was inhibited by high CO2tension. In cultures maintained under continuous illumination for one cell cycle, provision of 5% CO2led to enhanced growth, a relatively long S‐phase and a 4 h delay of the second cell division. In such cultures, the DNA content of parental cells (12 h L) was insufficient to support two cell divisions. The RNA/DNA ratio of the resulting zoospores was 10 compared to 4 in air cultures. These results provided evidence that the delay of the second cell division was a consequence of the delay in DNA production.
SEXUAL REPRODUCTION OFPERIDINIUM GATUNENSE(DINOPHYCEAE)1
Authors: Pfiester Lois A. 
Published: August 2007

ABSTRACTSexual reproduction was induced in the dinoflagellatePeridinium gatunenseNygaard when exponentially growing cells were inoculated into nitrogen deficient medium. Small thecate cells produced by division of vegetative cells then acted as gametes. Thecae of fusing gametes broke in the girdle region and were lost. Zygotes thus formed remained motile 3–5 days during which time they enlarged slightly with the newly formed theca becoming warty. Three to 5 days following plasmogamy the zygote became nonmotile, the protoplast contracted, and the cell wall thickened. Hypnozygotes with 4 nuclei were observedca.10–12 h following formation. Meiosis was inferred. Hypnozygotes germinated within 12 h of formation producing 2 vegetative cells which divided within a 24 h period. Attempts to induce sexual reproduction by inoculation of cells into media deficient in a number of basic elements other than N were unsuccessful.
THE EFFECTS OF SOME ECOLOGICAL FACTORS ON CELL SIZE OF THE HOT SPRING ALGA SYNECHOCOCCUS LIVIDUS (CYANOPHYTA)1
Authors: Kullberg Russell G. 
Published: August 2007

ABSTRACTAlgae were sampled along temperature gradients of 30 thermal springs in Colorado, Idaho, Montana and Wyoming. From a maximum temperature of 74.5 C downstream, to ca. 62 C, the diversity of the algae was limited to the various forms of Synechococcus lividus Copeland; from ca. 62 to 40–45 C it coexisted with other algae. When S. lividus was in direct sunlight the mean length was greatest at the highest temperatures of its existence, becoming shorter as the water cooled; the mean reduction in length was 0.132 μm for each 1 C reduction in temperature. The cells in a shaded stream did not exhibit the reduction in size with reduced temperature, but remained about the same length from 73 C downstream to 45 C. The longer cells from the highest temperatures of their existence in any stream could not become established in the cooler water downstream, so the range of cell lengths (diversity) became less as the water cooled. Unknown dissolved substance(s) depressed the upper temperature limit in two streams and had a reverse effect on the expected length–temperature relationship; the shortest cells were at the higher temperatures. Generally, total dissolved substances had a positive effect on the length; the longest cells were in the water with the highest total dissolved solids (TDS) at the upper temperature limits of 70–74.5 C. In the temperature range of 55–60 C the higher TDS were not as effective in developing longer cells.
STRUCTURAL, CHEMICAL AND ECOLOGICAL STUDIES ON IRIDESCENCE IN IRIDAEA (RHODOPHYTA)1
Authors: Gerwick William H. , Lang Norma J. 
Published: August 2007

ABSTRACTTransmission electron microscopy of the iridescent algae Iridaea flaccida (S & G) Silva, Iridaea cordata (Turn.) Bory var. cordata and I. cordata var. splendens (S & G) Abbott reveals a multilaminated cuticle covering the thallus. Experimental results show the cuticle: a) can be isolated intact by mechanical scraping or NaOH treatment; b) is iridescent by itself and the denuded thallus is not; and, c) is isolated without any subtending polysaccharide layer, cell walls, or cells. This cuticle acts as a thin layer producing the constructive and destructive light interference which is seen as iridescence. It is formed of alternating electron opaque and translucent layers with a total thickness of 0.5–1.6 μm. Analysis of mechanically isolated cuticle shows that it is composed of protein (50%), carbohydrate (ca. 40%), inorganic salts (5%) and some fatty acids (less than 1.0%). The electron opaque layers may correspond to protein‐rich regions and the electron translucent ones to regions rich in carbohydrates. The cuticle does not appear to affect photosynthesis or respiration, but rather, may protect the alga from physical factors such as desiccation and from predator injury. It is likely that the iridescence in other foliaceous red algae is caused by a similar structure.
ULTRASTRUCTURE OF A CHAIN‐FORMING DIATOM PHAEODACTYLUM TRICORNUTUM1
Authors: Borowitzka Michael A. , Chiappino Mary Louise , Volcani Benjamin E. 
Published: August 2007

ABSTRACTThe ultrastructure of a chain‐forming clone of the polymorphic diatom Phaeodactylum tricornutum Bohlin has been studied by scanning and transmission electron microscopy. Both fusiform and tri‐radiate cells are capable of forming chains. The cells, lacking any silica shell, are attached to each other at the central region of the theca, leaving the arms free. Neither homogenization nor sonication completely disrupts the chains. The attachment is due to fusion of the cell wall in the central region of the cell during cell wall deposition. This fusion results from failure of the cytoplasmic cleavage furrow to separate the plasma membranes of the two daughter cells sufficiently so that a single wall is deposited instead of two separate walls. Possible explanations for this are discussed.
NITRATE UPTAKE KINETICS AND CLONAL VARIABILITY IN THE NERITIC DIATOMBIDDULPHIA AURITA1
Authors: Underhill Peter A. 
Published: August 2007

ABSTRACTNitrate uptake experiments were conducted at 18 and 25 C on subtropical and temperate isolates of the neritic diatomBiddulphia aurita(Lyngb.) Breb. & Godey. Two clones (STX‐88 and B1) were grown in a 12:12 LD cycle in NO3‐limited continuous cultures used for uptake experiments. The half‐saturation constant (Ks) and the maximum NO3‐ uptake rate (Vm) were measured under conditions in which external NO3‐ concentration controlled uptake rate. The kinetic constants for both clones were higher at the higher temperature. The subtropical clone (STX‐88) had lower kinetic values than temperate clone (B1) at both temperatures. The differences appear to be of adaptive significance since STX‐88 has a NO3‐ uptake system, described by its lower Ksvalue, which minimizes the double stress effects of high temperature‐low NO3‐ concentration conditions characteristic of its habitat. Cytoplasmic enzyme electrophoretic analyses were conducted on the clones. Differences in banding patterns and mobilities showed evidence of allelic substitution. The results suggest genetic variation at the intraspecific level.
GROWTH OF A MARINE DIATOM AND A HAPTOPHYCEAN ALGA ON PHENYLALANINE OR TYROSINE SERVING AS SOLE NITROGEN SOURCE1
Authors: Landymore Arthur F. , Antia Naval J. 
Published: August 2007

ABSTRACTThe marine diatom Navicula incerta Hustedt and the haptophyte Isochrysis galbana Parke, both accustomed to grow on nitrate, were tested for their adaptive capacity for growth in axenic culture on 0.025–2.0 mM l‐, d‐, and dl‐isomers of phenylalanine and tyrosine as sole nitrogen sources. The diatom showed immediate and excellent growth (superior to nitrate) on l‐phenylalanine and l‐tyrosine but required prolonged periods of adaptation before growing on the d‐isomers, which growth was considerably slower. Isochrysis showed good growth on l‐phenylalanine after short adaptation, fair growth on low but poor growth on high concentrations of l‐tyrosine and no growth on the d‐isomers of both amino acids. The racemate (dl‐mixture) of each amino acid produced growth responses, from both algae, inferior to those of the corresponding l‐isomer, indicating competitive inhibition from the d‐isomer in the presence of equal amounts of its counterpart. Increasing tyrosine concentration was beneficial to growth of Navicula but markedly inhibitory or toxic to that of Isochrysis. Phenylalanine concentration appeared to benefit growth of both algae. Ecological considerations suggest that N. incerta may be habituated to utilize both aromatic amino acids in its native milieu.
IN SITU PRESERVATION OF THE TRANSVERSE FLAGELLUM OF PERIDINIUM CINCTUM (DINOPHYCEAE) FOR SCANNING ELECTRON MICROSCOPY1
Authors: Berdach James T. 
Published: August 2007

ABSTRACTThree‐dimensional structure of the transverse flagellum was studied by means of scanning electron microscopy (SEM) in Peridinium cinctum (O.F.M.) Ehrenberg. Several fixation and dehydration procedures were compared. Cells fixed, rapidly in 1% osmium tetroxide and critical‐point dried showed accurate preservation of structural features seen in living cells; in particular, both transverse and posterior flagella were retained in the furrows on the cell surface. Osmium‐fixed and freeze‐dried, samples were prone to cellular collapse and loss of flagella. Glutar‐aldehyde‐fixed and critical‐point dried cells showed a layer of material covering the thecal plates, most conspicuously over the girdle region; flagella were absent. Stereo‐pair micrographs illustrate the 3‐dimensional configuration of the transverse flagellum. Modifications of previous structural models are proposed.