bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ECOLOGY OF CLADOPHORA
Authors: Dodds Walter K. , Gudder Dolly A. 
Published: October 2004

ABSTRACT Cladophora is found in a variety of marine and fresh‐waters and provides habitat and food for numerous organisms. It may be the most ubiquitous macroalga in fresh‐waters worldwide. This filamentous green alga can reach nuisance levels as a result of cultural eutrophication. Taxonomic identification of Cladophora species is difficult. Taxonomy may be clarified by the simultaneous culture of known taxa and material derived from field collections under the same sets of culture conditions. This should eliminate ecotypic variations in morphology. Cladophora is predominantly benthic and is often found in regions of unidirectional flow or periodic wave action. Its metabolism, and morphology are related to hydrodynamic conditions. Nitrogen and phosphorus are the most commonly reported limiting nutrients. Cladophora is a mid‐ to late successional species in freshwaters where it is grazer resistant. In marine communities, however, it is considered an early opportunist and relatively palatable to invertebrates. Cladophora is colonized by a wide variety of epiphytes and motile animals because it can offer protection from predation, food (in the form of epiphytes or Cladophora itself), or a substrate that is anchored against flow disturbance. Species interactions that occur within Cladophora communities include 1) competition with other primary producers, 2) top‐down control of biomass, 3) association with nitrogen‐fixing epiphytes, 4) grazing on epiphytes by invertebrates, and 5) complicated foodwebs in marine intertidal and freshwater communities. Because Cladophora is found in many different habitats, its ecology varies significantly with locale.
BIOGEOGRAPHY OF STREAM MACROALGAE IN NORTH AMERICA1
Authors: Sheath Robert G. , Cole Kathleen M. 
Published: October 2004

ABSTRACTIn a survey of 1000 20‐m long stream segments in North America from 73°N to 10° N, 259 infrageneric taxa were identified, composed of 35% Chlorophyta, 24% Cyanophyta, 21% Chrysophyta, 20% Rhodophyta, and one species of Phaeophyta. The most common morphological forms were mats (42%), gelatinous colonies (23%), and gelatinous filaments (13%); the majority of taxa were vegetative (78%). The frequency of reproductive states varied among the biomes examined, with the highest values observed as follows: vegetative (85%) in the tundra, sexual (35%) in the deciduous forest, and asexual (21%) in the tropical rainforest. In terms of total species, the tundra had the lowest number (54), the boreal forest had the greatest number (100), and other well‐sampled biomes had 84 to 87. The Chlorophyta had the greatest species numbers in all biomes, and the relative contribution of this division did not vary significantly throughout the continent. With regard to similarity of species composition, the two closest associations were the boreal forest with the western coniferous forest and the eastern hemlock–hardwood forest with the deciduous forest. Species numbers per stream segment ranged from 0 to 11 (X̄= 3.1), cover ranged from 0 to 100% (X̄= 15%), and there was no significant difference in these values among the biomes. The cyanophyte Phormidium retzii (C. Ag.) Gom. was the most widespread species (in 172 segments and all biomes). The majority of species were found in moderate current velocities (X̄= 40 cm X̄ s−1), neutral to slightly alkaline pH (X̄= 7.5), and moderately low ion waters (X̄= 261 μS · cm−1). On both tropical and Arctic islands, there was no significant increase in total species or species numbers per stream segment with increasing surface area.
PURIFICATION AND CHARACTERIZATION OF PYRUVATE KINASE FROM THE GREEN ALGA CHLAMYDOMONAS REINHARDTII1
Authors: Wu Huacheng Bill , Turpin David H. 
Published: October 2004

ABSTRACTA single form of pyruvate kinase was isolated from the green alga Chlamydomonas reinhardtii Dang. (Chlorophyta) and partially purified over twentyfold, yielding a final specific activity of 2.68 μmol pyruvate produced‐min‐1.mg‐1 protein. Studies of its physical characteristics reveal that the pyruvate kinase is heat stable, is partially inactivated by sulfhydryl reagent N‐ethylmaleimide, and has a pH optimum at 6.8 and a native molecular mass of 224 kDa. Immunological precipitation and western blotting, using antibodies raised against Selenastrum minutum Naeg. (Chlorophyta) cytosolic pyruvate kinase, reveal that C. reinhardtii pyruvate kinase possesses a subunit molecular mass of 57 kDa, indicating a homo‐tetrameric structure. This enzyme exhibits an absolute requirement for a divalent cation that can be fulfilled, by Mg2+. The monovalent cation K+ acts as a strong activator. The Km values for phosphoenolpyruvate and adenosine diphosphate (ADP) are 0.16 mM and 0.18 mM, respectively. The enzyme is capable of using other nucleotides with Vmax for UDP, GDP, IDP, and CDP of 70%, 55%, 53%, and 25% of that with ADP, respectively. Dihydroxyacetone phosphate, ribulose 1,5‐bisphosphate, adenosine monophosphate (AMP), ribose‐5‐phosphate, and glyceraldehyde‐3‐phosphate are activators, whereas glutamate, orthophosphate, adenosine triphosphate (ATP), citrate, isocitrate, malate, oxalate, phosphoglycolate, and 2,3‐diphosphoglycerate are potent inhibitors of this enzyme. Dihydroxyacetone phosphate can reverse the inhibition by glutamate and phosphate. These properties are discussed in light of pyruvate kinase regulation during anabolic and catabolic respiration. Substrate interaction and product inhibition studies indicate that ADP is the first substrate bound to the enzyme and pyruvate is the last product released (Ordered Bi Bi mechanism).
EFFECTS OF VARIATION IN TEMPERATURE. I. ON THE BIOCHEMICAL COMPOSITION OF EIGHT SPECIES OF MARINE PHYTOPLANKTON1
Authors: Thompson Peter A. , Guo Ming‐xin , Harrison Paul J. 
Published: October 2004

ABSTRACTThe influence of temperature on the biochemical composition of eight species of marine phytoplankton was investigated. Thalassiosira pseudonana Hasle and Heim‐dal, Phaeodactylum tricornutum Bohlin and, Pavlova lutheri Droop (three of eight species studied) had minimum values of carbon and nitrogen quotas at intermediate temperatures resulting in a broad U‐shaped response in quotas over the temperature range of 10 to 25°C. Protein per cell also had minimum values at intermediate temperatures for six species. For T. pseudonana, P. tricornutum, and P. lutheri, patterns of variation in carbon, nitrogen, and protein quotas as a function of temperature were similar. Over all species, lipid and carbohydrate per cell showed no consistent trends with temperature.Only chlorophyll a quotas and the carbon: chlorophyll a ratios (θ) showed consistent trends across all species. Chlorophyll a quotas were always lower at 10°C than at 25°C. Carbon: chlorophyll a ratios (θ) were always higher at 10°C than at 25°C. We suggest that although θ consistently increases at lower temperatures, the relationship between temperature and θ ranges from linear to exponential and is species specific. Accordingly, the interspecific variance in θ that results from species showing a range of possible responses to temperature increases as temperature declines and reaches a maximum at low temperatures. High photon flux densities appear to increase the potential interspecific variance in the carbon: chlorophyll a ratio and therefore exacerbate these trends.
TWO TYPES OF CYTOPLASMIC CLEAVAGE IN THE COENOCYTIC SOIL ALGAPROTOSIPHON BOTRYOIDES(CHLOROPHYCEAE)1
Authors: Kouwets Frans A. C. , van der Schaaf Peter J. 
Published: October 2004

ABSTRACTCytokinesis in the coenocytic green algaProtosiphon botryoides(Kütz.) Klebs was studied with transmission electron microscopy. In vegetative cells, nuclei with associated basal bodies and dictyosomes are scattered throughout the cytoplasm. Mature cells may develop either multinucleate resting spores (coenocysts) or uninucleate zoospores. Cytokinesis may be preceded by contraction of the protoplast due to the disintegration of vacuoles that are present in larger, siphonous cells.The formation of coenocysts in ageing, siphonous cells, is signalled by cleavage of the chloroplast and the development of arrays of phycoplast microtubules in one or more transversely oriented planes through the cell. Nuclei with associated basal apparatuses stay dispersed throughout the cytoplasm; the basal bodies apparently are not involved in organization of the phycoplast. The plasma membrane invaginates, resulting in a centripetal cleavage of the protoplast into two or more multinucleate daughter protoplasts. Simultaneously, wall material is deposited along the outside of the daughter protoplasts by dictyosome‐derived vesicles, and finally two or more thick‐walled coenocysts are formed.The formation of zoospores, on the other hand, is signalled by clustering of the nuclei in one or more groups depending on the shape of the mother cell. The nuclei become arranged with the associated basal apparatuses facing toward the center of the cluster. Bundles of phycoplast microtubules develop between the nuclei, radiating from the center of a cluster toward the plasma membrane; basal apparatuses or associated structures apparently are involved in organization of the phycoplast. Cleavage furrows grow out centrifugally along these bundles of micro‐tubules, fed by dictyosome‐derived vesicles. No wall material is deposited. An additional mitotic division occurs during cleavage, and finally numerous uninucleate, wall‐less, biflagellate zoospores are formed. The ultrastructural features of the two different types of cytoplasmic cleavage associated with two different types of daughter cells have not previously been reported for chlorophycean algae.
COMPARATIVE PHYSIOLOGY AND BIOCHEMISTRY AND TAXONOMIC ASSIGNMENT OF THE CHLORELLA (CHLOROPHYCEAE) STRAINS OF THE CULTURE COLLECTION OF THE UNIVERSITY OF TEXAS AT AUSTIN1
Authors: Kessler Erich , Huss Volker A. R. 
Published: October 2004

ABSTRACTThe species of the genus Chlorella exhibit considerable biochemical and physiological differences. Therefore, it is important to select for and utilize in research or biotechnology correctly identified strains of the species having the most favorable properties for the respective project. We examined the Chlorella strains of the University of Texas collection at Austin, Texas, according to species‐specific chemotaxonomic characters and assigned 58 strains to 10 well‐established species (only 17 of these strains were correctly named before).
CYCLOMORPHOSIS IN SCENEDESMUS ARMATUS (CHLOROPHYTA): AN ORDERED SEQUENCE OF ECOMORPH DEVELOPMENT1
Authors: Trainor Francis R. 
Published: October 2004

ABSTRACT Scenedesmus armatus (Chod.) Chod, growth and morphology were monitored in medium 7 (oligotrophic) and Bristol's medium (eutrophic); cultures in both media were incubated at 10 and 22° C. Growth rate at 10° C was reduced, i.e. only one doubling in 7 days in medium 7 and 2.3 doublings in Bristol's, compared to 4.3 and 6 doublings at 22° C over the same period. Unicells as well as cells of colonies were larger at the cold temperature. The lengths of cells were not significantly different regardless of temperature or medium, but cell width was markedly increased at the lower temperature. Additionally, an arcuate, eight‐celled, multispined ecomorph, which resembled several previously described taxa, was produced at 10° C. It becomes a component of a previously published ordered sequence of ecomorph development for this species.Based on data now accumulated in both the laboratory and the field, these temporal changes are interpreted to be a cyclomorphosis, driven by a coupling of nutrient availability and temperature. Within the addition of new cold temperature (spring) ecomorphs, the ordered sequence of ecomorphs for S. armatus is a succession from unicells to multispined eight‐celled colonies to quadricaudate colonies, ending with acaudate four‐celled ecomorphs.
CULTURE STUDIES ON THE RELATIONSHIP BETWEENSCHIZYMENIAANDHAEMATOCELIS(GIGARTINALES, RHODOPHYCEAE) FROM THE PACIFIC COAST OF NORTH AMERICA1
Authors: DeCew Thomas C. , Silva Paul C. , West John A. 
Published: October 2004

ABSTRACTCarpospores fromSchizymenia pacifica(Kylin) Kylin (Gymnophlaeaceae) from California formed crusts anatomically identical toHaematocelis rubensJ. Agardh (Cruoriaceae). Tetraspores ofH. rubensfrom Monterey, California, and Baja California, Mexico, germinated to form basal discs from which arose upright multiaxial blades with a filamentous medulla and cortical gland cells. Pro‐carps and spermatangia were present on the same blades; subsequently, cystocarps characteristic ofSchizymenia pacificadeveloped. Re‐examination of herbarium specimens suggests that the foliose tetrasporangial phases previously reported asS. pacificaare referable toHalymenia, Dilsea, Cryptonemia, orTurnerella. Schizymenia pacifica(type locality: San Juan Islands, Washington) thus is considered to be the gametophyte in the life history ofHaematocelis rubens(type locality: Brest, France), which has also been reported to be the tetrasporophyte ofS. dubyi(Chauvin ex Duby) J. Agardh (type locality: Cherbourg, France). Atlantic and Pacific gametophytes and tetrasporophytes are anatomically very similar, suggesting that only one species is involved, but critical studies must be made before a decision on this taxonomic question can be reached.Haematocelis zonalisDawson et Neushul (type locality: Anacapa Island, California) is considered to be a growth form of the tetrasporangial phase ofS. pacifica.
A METHOD OF OBTAINING AXENIC CULTURES OF TRENTEPOHLIA SPP. (CHLOROPHYTA)1
Authors: Lim Melin , Ong Bee‐Lian , Wee Yeow‐Chin 
Published: October 2004

ABSTRACTAxenic cultures of Trentepohlia species are necessary for the study of growth and hysiological characters of the algae. We describe the use of a Sherman micromanipulator to isolate filaments from samples of T. aurea and T. odorata collected from their natural habitats. These filaments were then used as inocula for the establishment of axenic cultures. In the case of T. aurea, further treatment with lactic acid was necessary.
THE FLAGELLAR APPARATUS OFHYMENOMONAS CORONATA(PRYMNESIOPHYTA)1
Authors: Roberts Keith R. , Mills Jimmy T. 
Published: October 2004

ABSTRACTThe ultrastructure ofHymenomonas coronataMills was reinvestigated to determine the microarchitecture of the flagellar apparatus. Cell morphology and flagellar apparatus structure are very similar to those ofPleurochrysis.Some important variations occur. First, a crystalline root (= compound root) is absent on microtubular root 1. Second, a two‐stranded microtubular root emanates at a right angle from microtubular root 2. Third, a fibrous root emanates from the dorsal region between the basal bodies and extends to the cell's right, paralleling microtubular root 3. These similarities and variations in flagellar apparatus characters are discussed in reference to known variations in the Prymnesiophyta.
VEGETATIVE GROWTH OF ACETABULARIA ACETABULUM (CHLOROPHYTA): STRUCTURAL EVIDENCE FOR JUVENILE AND ADULT PHASES IN DEVELOPMENT1
Authors: Nishimura Nathan J. , Mandoli Dina F. 
Published: October 2004

ABSTRACTWe characterized vegetative development in two inbred cell lines of Acetabularia acetabulum (L.) Silva. Cell growth occurred at the apex and by elongation of older interwhorls throughout vegetative development. Although cell length and hairs per whorl increased regularly during development, interwhorl length, hair persistence on the stalk, and complexity of each whorl (degree of branching of whorl hairs) showed sharp discontinuities during development in both cell lines. The first (earliest) discontinuity, formation of a short interwhorl, was the sixth interwhorl made in all cells. Even though cell line Aa1055 was twice the height ofAa4010 when mature, cells in both lines were 0.8–1.0 cm tall after formation of the short interwhorl. The second discontinuity, increases in hair persistence on the stalk and complexity of each whorl of hairs, began shortly before cap initiation. We propose the following nomenclature: 1) that slower growth before formation of the short interwhorl be called “juvenile”; 2) that more rapid growth after formation of the short interwhorl be called “adult”; and 3) that adult growth be separated into “early” and “late” phases by the discontinuities in whorl hair characteristics. The proposed developmental phases (juvenile, early adult, and late adult) are temporally sequential and spatially stacked.
DNA EXTRACTION METHODS FOR KELP (LAMINARIALES) TISSUE1
Authors: Mayes Charlene , Saunders Gary W. , Tan Ian H. , Druehl Louis D. 
Published: October 2004

ABSTRACTNewly adapted extraction methods for harvesting total cellular DNA from kelp (Laminariales; Phaeophyta) exploit the life‐history stages of these heteromorphic algae. Earlier techniques, developed primarily for chloroplast DNA extraction, were time consuming and labor intensive and required large quantities of fresh sporophyte tissue. In contrast, the new methods expedite DNA extraction by employing dried sporophyte laminae or fresh gametophyte filaments and meiospores. The current methods require less tissue and procedural manipulation, reducing the time and labor involved in DNA extraction. Additionally, the current methods were successfully employed to extract DNA from herbarium specimens up to 22 years old. Total cellular DNA yields were 12.8 and 26.4 μg:g−1 from dried laminae,: 1.9 and 11 μg from small volumes of concentrated gametophyte filaments (25 μL), and 43 to 54.5 μg from pellets of isolated meiospores (50 μL). Following purification on Sepharose columns, DNA from all three sources was sufficiently pure for molecular applications, including restriction endonuclease digestion, Southern blot‐hybridizations, and amplification via the polymerase chain reaction.
LITHIUM CHLORIDE EXTRACTION OF DNA FROM THE SEAWEED PORPHYRA PERFORATA (RHODOPHYTA)1
Authors: Hong Yong‐Ki , Coury Daniel A. , Polne‐Fuller Miriam , Gibor Aharon 
Published: October 2004

ABSTRACTLithium chloride facilitates the softening of cell walls resulting in a simple, quick (2 h) method for DNA extraction from the red seaweed Porphyra perforata J. Agardh. A 5‐min treatment of tissues in Lid at 55°C extracts DNA that is relatively free of the viscous polysaccharides and proteins that are usually coextracted in large amounts from cell walls and cytoplasm. This protocol does not require grinding of tissues, hydroxyapatite binding, cetyl trimethyl ammonium bromide treatments, enzymatic treatments, phenol extraction, or CsCl‐gradient centrifugation. The resulting DNA is of sufficient quality to be used as a template for polymerase chain reaction amplification.
THE INFLUENCE OF SALINITY AND TEMPERATURE COVARIATION ON THE PHOTOPHYSIOLOGICAL CHARACTERISTICS OF ANTARCTIC SEA ICE MICROALGAE1
Authors: Arrigo Kevin R. , Sullivan Cornelius W. 
Published: October 2004

ABSTRACTThe responses of sea ice microalgae to variation in ambient irradiance (0 to 150 μE · m−2· s−1), temperature (–6° to + 6° C), and salinity (0 to 100 ppt) were tested to determine whether these variables act independently or in concert to influence rates of microalgal photosynthesis. The photosynthetic efficiency and maximum photosynthetic rate for sea ice microalgae increased as a function of incubation temperature between ‐6° and + 6° C. Furthermore, photosynthetic efficiency, maximum photosynthetic rate, and quantum yield were greatest at salinities between SO and 50 ppt. In contrast, the mean specific absorption coefficients were lowest near seawater salinities, and the saturating irradiance, Is, appeared to be inversely proportional to salinity. Results also suggest that the effects of salinity on the growth of sea ice microalgae are independent of those elicited by temperature or light, and that the functional relationship between salinity and light or temperature is multiplicative. This information is essential to the proper formulation of algorithms used to describe algal growth in environments where light, temperature, and salinity are changing simultaneously, such as within sea ice or within the water column at the marginal ice edge zone.
DAY AND NIGHT KINETICS OF GROWTH RATE IN GREEN, BROWN, AND RED SEAWEEDS1
Authors: Lüning Klaus 
Published: October 2004

ABSTRACTGrowth rates in terms of area increase per 30 min were measured in flat thalli of several seaweed, species by means of computer‐assisted image analysis, at 12 h light per day and a photon fluence rate of 20 μmol · m‐2· s−1. Light fields included white fluorescent, imitated underwater, blue, green, and red light. In the green alga Ulva pseudocurvata Koeman et Hoek, blue light caused an immediate reduction of thallus area and growth rate after the onset of light, whereas green light and red light resulted in an initial peak in growth rate followed by inhibition 60 min after the onset of light. More growth was observed in darkness than in blue light in U. pseudocurvata. All brown and red algae tested, with Laminaria saccharina (L.) Lamour. and Palmaria palmata Stackh. as the main investigated species, grew faster during the day than during the night, irrespective of light quality during the main light phase. The upper intertidal red alga Porphyra umbilicalis (L.) J. Ag. achieved most of its thallus expansion per 24 h during the first 3 h of the light phase, with maximum growth rates of 2–3% increase in area per hour. Maximal growth rates were 0.7% for juvenile laminarian sporophytes and were lower than this in Palmaria palmata and other perennial red algae. The temporary growth inhibition by light in Ulva pseudocurvata suggests photomorphogenetic events, similar to the kinetics of stem elongation in higher plant seedlings after blue or red light pulses in darkness.
ORIENTATION OF SWIMMING FLAGELLATES BY SIMULTANEOUSLY ACTING EXTERNAL FACTORS1
Authors: Kessler John O. , Hill Nicholas A. , Häder Donat‐P. 
Published: October 2004

ABSTRACTThe directionality of phototaxis combined with gravitaxis was investigated experimentally for populations of the swimming alga Euglena gracilis Klebs. Two irradiances were used: a “weak” irradiance to elicit positive phototaxis and a “strong” irradiance to elicit negative phototaxis. In addition, by changing the density of cells in the suspension, the number of collisions between cells was varied to determine the effects of these collisions on the distribution of swimming directions in both the absence and the presence of illumination. We found that positive phototaxis was associated with a broader distribution of swimming directions than was negative phototaxis. In the latter case, the effect of phototaxis dominated over that of gravitaxis. Experiments on another swimming alga, Chlamydomonas nivalis Wille, showed that collisions between cells degraded the directionality of gravitaxis.
ISOLATION AND PRELIMINARY CHARACTERIZATION OF THREE CHLAMYDOMONAS STRAINS INTERFERTILE WITH CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1
Authors: Spanier Jonathan G. , Graham Jennifer E. , Jarvik Jonathan W. 
Published: October 2004

ABSTRACTThree new strains of the unicellular green alga Chlamydomonas reinhardtii Dangeard were isolated from soil. The isolates differed from one another and from standard laboratory strains of C. reinhardtii in a number of traits, including heavy metal resistance, protein composition, and mitochondrial DNA length. The new isolates also exhibited distinctive restriction fragment length polymorphisms in their nuclear, chloroplast, and mitochondrial genomes. The new isolates were interfertile with the standard laboratory strains and appeared to transfer chloroplast and mitochondrial genomes in a similar manner, that is, predominantly from the material (mt+) and paternal (mt−) parents, respectively.