bluuebunny/crossref_metadata_2025_split huggingface dataset:
INTRASPECIFIC COMPARISONS OF NITRATE UPTAKE IN THREE MARINE DIATOMS1
Authors: Romeo Anthony J. , Fisher Nicholas S. 
Published: August 2007

ABSTRACTShort‐term (within 5 min) and long‐term (≤2 h) rates of nitrate uptake were determined for the marine diatoms, Nitschiella longissima (Cleve), Skeletonema costatum (Greville) Cleve and Asterionella japonica (Cleve). Pigment levels, cell carbon, nitrogen and cell volume were also determined for cells in the logarithmic and stationary phases of growth. For each species, one clone isolated from oligotrophic coastal water and one clone isolated from eutrophic coastal water were compared. Long‐term NO3− uptake typically followed saturation kinetics describable by the Michaelis‐Menten expression. Under experimental conditions, half‐saturation constants ranged from 0.6 to 2.2 μM NO3−. Generally, the oligotrophic clones had lower Ks and Vmax (on a per cell basis) than their eutrophic counterparts, though this was only statistically significant in one pair of clones. Eutrophic and oligotrophic clones also differed in their short‐term response to nutrient addition; oligotrophic clones showed greatest rate of uptake at the lowest nitrate addition while uptake by eutrophic clones increased with increasing nitrate concentration. However, all clones had very similar Vmax values expressed on a dry weight basis. Under N‐starvation, cellular C and pigment levels (and N to a lesser extent) generally declined more in eutrophic than in oligotrophic clones. While the differences between inshore and offshore clones were not great, the results are consistent with the hypothesis that eutrophic waters support algae which grow faster and are less conservative biochemically than cells in oligotrophic waters.
STRUCTURE AND DEVELOPMENT OF THE SECRETORY CELLS AND DUCT SYSTEM IN MACROCYSTIS PYRIFERA (L.) C. A. AGARDH1
Authors: Grenville D. J. , Peterson R. L. , Barrales H. L. , Gerrath J. F. 
Published: August 2007

ABSTRACTSporophytes of Macrocystis pyrifera (L.) C. A. Agardh of various stages of growth were studied by light microscopy to determine the initiation and ontogeny of secretory cells and the accompanying duct system. Secretory cells are initiated by asymmetric, periclinal divisions of meristoderm cells; subsequent mitoses increase the number of secretory cells associated with each duct. Duct formation occurs by schizogeny of anticlinal cell walls adjacent to the site of secretory cell initiation. Differences in distribution and structure of the duct system occur in various parts of the sporophyte. The duct system does not have openings directly to the sporophyte surface. Histochemical techniques showed that the duct contents are mostly sulfated polysaccharides with perhaps some lipid.
MORPHOLOGY AND DISTRIBUTION OF NUCLEI DURING DEVELOPMENT IN CYMOPOLIA BARBATA (CHLOROPHYCOPHYTA, DASYCLADALES)1
Authors: Liddle Larry B. , Thomas Jewel P. , Scott Joe 
Published: August 2007

ABSTRACTThe morphology and distribution of a variety of types of nucleus in the apex, in young and mature gametangia, and in older regions of the Cymopolia cell were studied by light and electron microscopy. Spherical and convoluted nuclei 2–7μm in diameter were observed in apical regions of the vegetative siphon. Nuclei 4 μm in diameter were present in the young primary laterals and in developing gametangia. A single characteristic nucleus migrates from the siphon into the primary lateral of the second basipetal whorl. It is further transported into one of several possible secondary laterals and determines the development of gametangia which become multinucleate in the fourth or fifth whorls. Nuclei are characterized by size, shape, nucleolar morphology, nucleoplasmic inclusions and the ultrastructure of the perinuclear cytoplasm. Although no “primary nucleus” characteristic of the uninucleate genera, Acetabularia and Batophora was observed, some nuclei of Cymopolia have features in common with secondary nuclei of these genera.
STRUCTURE, LIFE HISTORY AND SYSTEMATICS OF RHOICOSPHENIA (BACILLARIOPHYTA). II. AUXOSPORE FORMATION AND PERIZONIUM STRUCTURE OF RH. CURVATA1
Authors: Mann David G. 
Published: August 2007

ABSTRACTReproduction in Rhoicosphenia curvata (Kütz.) Grun. is isogamous. The two auxospores formed expand parallel to the apical axes of the gametangial cells. Expansion is bipolar and leads to the formation of a slightly curved, tapering cell, in which the initial valves are laid down. The perizonium consists of transverse and longitudinal bands. The transverse series, of 35 or so bands, is laid down centrifugally as the auxospore expands and can be classified into three groups on the basis of band morphology. All except the central band are open hoops, orientated so that their ends lie in the midline of the less convex, ventral side of the auxospore. The bands have fimbriate margins on one or both sides, and overlap one another from center to either pole. The longitudinal series includes 5 bands—a wide central band, with two on either side: again, the bands overlap one another from the center outwards. The initial epivalve of the new generation forms beneath the dorsal side of the auxospore, on the opposite side from the longitudinal perizonial series. Comparisons are made with other genera and the relevance of auxospore studies to an understanding of diatom morphogenesis is discussed.
SIZE‐DEPENDENT PHOSPHORUS UPTAKE KINETICS AND CELL QUOTA IN PHYTOPLANKTON1
Authors: Smith Ralph E. H. , Kalff Jaap 
Published: August 2007

ABSTRACTThe allometric equation, y = aXb, described the interspecific variation of phosphate uptake kinetics and cell quota with phytoplankton cell size and showed that smaller cells are superior in uptake rate to large. Species‐specific measurements, made by track autoradiography in phosphorus deficient cultures of communities from a phosphorus‐limited lake, revealed that eight different species did not differ significantly in the Michaelis‐Menten half‐saturation constant, Km. However, both saturated uptake rates (Vmax) and the initial slope of the uptake curve (Vmax:Km) decreased per unit biomass with increasing cell size. Biomass‐specific cell phosphorus quotas also decreased with increasing cell volume, but less rapidly than did Vmax or Vmax: Km. Comparable data from the literature showed that marine species were superior in phosphorus uptake to freshwater species of similar size, but allometric variation of kinetics appeared to exist within both groups. Together with a variable internal stores model of phosphorus‐limited growth, the allometric relationships of uptake kinetics and quotas predicted competition to favor smaller cells, with a differential in growth rate diminishing as competitive intensity increased.
AUTOINHIBITION OF SPORE GERMINATION IN NOSTOC SPONGIAEFORME (CYANOPHYCEAE)1
Authors: Thiel Teresa , Wolk C. Peter 
Published: August 2007

ABSTRACTMedium in which cultures of Nostoc spongiaeforme Ag. have sporulated contains one or more substances which inhbit the germination of spores (akinetes) of this organism. Germination of spores occurs rapidly in the absence of these substances, but is virtually completely suppressed in their presence.
PRIMARY PRODUCTIVITY OF MARINE MACROALGAL FUNCTIONAL‐FORM GROUPS FROM SOUTHWESTERN NORTH AMERICA1
Authors: Littler Mark M. , Arnold Keith E. 
Published: August 2007

ABSTRACTNew productivity data are given for 62 macroalgal species from 6 intertidal habitats spanning a latitudinal range of nearly twelve degrees on the Pacific Coast of south‐western North America. Our data, utilizing a functional‐form group approach, support an hypothesis relating morphological forms to photosynthetic performances. Specifically, the Sheet‐Group showed the highest productivity (mean apparent net photo synthetic performance = 5.16 mg C · g−1· h−1) with a reduction of ca. two‐fold between each of the following four groups: Filamentous‐Group (2.47), Coarsely Branched‐Group (1.30), Thick Leathery‐Group (0.76) and Jointed Calcareous‐Group (0.45). The Crustose‐Group had by far the lowest mean net productivity being only 0.07 mg C · g−1· h−1. The‐functional‐form group approach is a promising tool for predicting the outcome of productivity‐related ecological and evolutionary processes without being restricted temporally, geographically or taxonomically.
SELF‐STERILE AND MATURATION‐DEFECTIVE MUTANTS OF THE HOMOTHALLIC ALGA, CHLAMYDOMONAS MONOICA (CHLOROPHYCEAE).1
Authors: VanWinkle‐Swift Karen P. , Bauer John C. 
Published: August 2007

ABSTRACTHomothallic sexual reproduction in Chlamydomonas monoica Strehlow culminated in the formation of mature, chloroform‐resistant zygospores (zygotes) in clonal culture. Early in the zygote maturation process, a distinctive “primary zygote wall” was released into the culture medium where it remained stable for at least several days. This wall appeared as a rigid, darkly‐outlined, and often multilayered structure, as viewed by phase contrast microscopy. From a sample, of 2500 individual clones isolated after ethyl methanesulfonate mutagenesis, five maturation‐defective strains (zym) produced abnormal zygotes which failed to release a primary zygote wall, failed to develop the normal reticulate zygospore wall, and disintegrated within five days. These strains were utilized to identify additional mutants which were sexually competent, but self‐sterile (het). Mixed cultures of the zym and het mutant strains were found to contain numerous, fully‐matured, chloroform‐resistant zygospores and discarded primary zygote walls. In combination, the two types of mutants provided a useful system for the selective recovery of heterozygous zygospores, thus facilitating genetic studies on a homothallic Chlamydomonas.
IN‐SITU MORPHOLOGY AND OCCURRENCE OF EUCARYOTIC PHOTOTROPHS OF BACTERIAL SIZE IN THE PICOPLANKTON OF ESTUARINE AND OCEANIC WATERS1
Authors: Johnson Paul W. , Sieburth John McN. 
Published: August 2007

ABSTRACTConcentrates of the picoplankton (0.2–2.0 μm) sized fraction from the euphotic zone of estuarine and oceanic waters were examined by transmission electron microscopy. In addition to the numerous phototrophic procaryotes (chroococcoid cyanobacteria) previously reported, small phototrophic eucaryotes were observed in 20 of 25 samples examined. Micromonas pusilla (Butcher) Manton and Parks, a 1 × 1.5 μm flagellate, was abundant in estuarine samples in summer. Similar sized cells of non‐flagellated chlorophytes, either Nannochloris Naumann or Chlorella Beijerinck, were observed sporadically in many samples. The most ubiquitous microalga was a scaled, non‐flagellated prasinophyte that occurred at 9 of 15 different locations on 15 of 20 sampling dates in water samples from Iceland to the Caribbean Sea, This tiny alga (0.5 to 1.0 μm in diam.) is probably the smallest known photo‐trophic eucaryote and has not heretofore been described. Enrichment cultures using conventional techniques on several cruises yielded only the Chlorella‐type of green alga, as well as numerous isolates of unicellular chroococcoid cyanobacteria.
SELENIUM STIMULATES GROWTH OF MARINE MACROALGAE IN AXENIC CULTURE1
Authors: Fries Lisbeth 
Published: August 2007

ABSTRACTThe marine brown alga Fucus spiralis L. and the red alga Goniotrichum alsidii (Zanard) increase their growth upon the, addition of SeO32‐ or SeO42‐ when cultivated axenically in the artificial seawater ASP6 F2. In the concentration range 1 · 10−10‐1 · 10−7 M there are two optima, one at 3.3 · 10−10 M and another at 3.3 · 10−8 M. α‐To‐copherol, often administered together with selenium to mammals suffering from selenium deficiency, gives no additive effect with selenium, but α‐tocopherol in the concentration range 1 × 10−7‐1 × 10−6 M does influence the morphology of the Fucus plants. Organically bound selenium has no effect.
EFFECTS OF ICE ON ASCOPHYLLUM NODOSUM WITHIN THE GREAT BAY ESTUARY SYSTEM OF NEW HAMPSHIRE‐MAINE12
Authors: Mathieson Arthur C. , Penniman Clayton A. , Busse Paula K. , Tveter‐Gallagher Eleanor 
Published: August 2007

ABSTRACTThe, effects of ice on Ascophyllum nodosum (L.) Le Jolis within the Great Bay Estuary System of New Hampshire‐Maine, U.S.A. were assessed during the winter of 1980–81. Approximately 50% of the plants late fall standing crop, or an estimated 136 tonnes dry weight, was removed by ice‐rafting. Pieces of Ascophyllum removed averaged 22 cm in length, 15 g in fresh weight and generally represented 2–3 years of growth. Although the winter of 1980–81 wax somewhat extreme, a similar pruning process probably occurs each year contributing to the characteristic bushy habit of attached inner estuarine plants. Ascophyllum fragments rafted in ice and deposited into salt marshes are suggested as a major source of the, ecad scorpioides (Hornemann) Hauck.
A COMPARATIVE CYTOCHEMICAL STUDY OF VOLVOCACEAN MATRIX POLYSACCHARIDES1
Authors: Crayton M. A. 
Published: August 2007

ABSTRACTThe colonial matrices of the volvocacean algae were examined for the presence of sulfated and carboxylated polysaccharides. These results were compared to a similar examination of the single‐celled Chlamydomonas reinhardtii Dang. The colonial algae examined were Pandorina morum Bory, Eudorina elegans Ehr., Platydorina caudata Kofoid, Pleodorina californica Shaw, Pleodorina illinoisensis Kofoid and Volvox carteri var. nagariensis Iyengar. Alcian blue staining of whole colonies at pH 0.5 and 2.5 showed evidence for the presence of both sulfated and carboxylated polysaccharides in the extracellular matrix. Quantitative measurement of alcian blue bound to solubilized matrices supported the in vivo results. There was a trend toward an increase in sulfated polysaccharides in the more evolutionary advanced forms with the exception of Pleodorina. This trend was readily seen in the sulfate: carboxyl ratios: Pandorina morum—0.4, Eudorina elegans—1.0, Platydorina caudata—2.1 and Volvox carteri—2.2. The acidic nature of the Pleodorina matrix with a sulfate: carboxyl ratio of 0.2 appeared to be more like that of Pandorina rather than that of the more advanced Volvox.
NITROGEN ALLOCATION AND STORAGE PATTERNS IN GRACILARIA TIKVAHIAE (RHODOPHYTA)1
Authors: Bird Kimon T. , Habig Clifford , DeBusk Thomas 
Published: August 2007

ABSTRACTInternal nitrogen pools in thalli of Gracilaria tikvahiae McLachlan were examined in three experiments as a function of total nitrogen content of the thallus, nitrogen deprivation, and nitrogen resupply. Amino acids and proteins appeared to form the major nitrogen storage pools in G. tikvahiae, while DNA appeared to be relatively unimportant in this regard. Inorganic nitrogen in the forms of NH4+ and NO3− was found in the thalli; however, its contribution to the total nitrogen, pools was small. Within the protein pool, the phycoerythrin pigments appear important as a source of nitrogen when thalli are initially becoming nitrogen limited. In general, there was an inverse relationship between the levels of nitrogen and the carbohydrate content of the algal thalli.
EFFECTS OF VARIATIONS IN LIGHT INTENSITY ON THE EFFICIENCY OF GROWTH OF SKELETONEMA COSTATUM (BACILLARIOPHYCEAE) IN A CYCLOSTAT1
Authors: Cosper Elizabeth 
Published: August 2007

ABSTRACTThe relative importance of respiration and organic carbon release to the efficiency of carbon specific growth of Skeletonema costatum (Grev.) Clave was evaluated over a light range from 1500–15 μE · m−2· s−1. Net growth efficiency ranged from 0.45–0.69 with a maximum at 130 μE · m−2· s−1. Respiration was 93% or more of the variations in growth efficiency. Organic carbon release ranged from 0–7% of gross production and increased with light intensity. Carbon specific particulate production was a hyperbolic function of incident light intensity and was related exponentially to particulate carbon production per unit chlorophyll a. Full sunlight conditions, 1500 μE · m−2· s−1, did not induce photoinhibition of gross production. Variations in the efficiency of growth of S. costatum were minimized over a wide range of light intensities mainly because of variations in cellular pigments which permitted the efficient utilization of available light energy, and a reduction in the losses of carbon which increases the growth rate, possibly as a consequence of the recycling of respired carbon within the cell.
SCHMITZIA EVANESCENS SP. NOV. (RHODOPHYTA, GIGARTINALES) A NEW SPECIES OF CALOSIPHONIACEAE FROM THE NORTHEASTERN NEW ZEALAND COAST1
Authors: Hawkes Michael W. 
Published: August 2007

ABSTRACTA new red alga, Schmitzia evanescens sp. nov. (Gigartinales), is described from the northeastern coast of North I., New Zealand. Gametophytes are diminutive, delicate, mucilaginous spring annuals which grow subtidally on cobble substrata. The uniaxial construction and carposporophyte development place this new taxon in the Calosiphoniaceae, a family of only two genera, Calosiphonia H. M. Crouan et P. L. Crouan and Schmitzia P. C. Silva. This is the first report of this family in New Zealand. The new species has vegetative features of both these genera, but is assigned to Schmitzia on the basis of its unusual carposporophyte development in which the gonimoblast initial arises directly from the connecting filament at some distance from the undifferentiated intercalary auxiliary cell. Because recent investigators of other red algal genera with a similar carposporophyte development have questioned the validity of site of gonimoblast initiation as a generic criterion it is suggested that the separation of Schmitzia and Calosiphonia should be re‐evaluated. These and several other genera in the Gymnophlaeaceae, Pseudoanemoniaceae, Dumontiaceae and Gloiosiphoniaceae, can be considered, on morphological and reproductive grounds, to be relatively simple and therefore perhaps primitive members of the Rhodophyta.
EPIPHYTES ON CLADOPHORA GLOMERATA IN THE GREAT LAKES AND ST. LAWRENCE SEAWAY WITH PARTICULAR REFERENCE TO THE RED ALGA CHROODACTYLON RAMOSUM (= ASTEROCYTIS SMARGDINA)1
Authors: Sheath Robert G. , Morison Mary O. 
Published: August 2007

ABSTRACTThe range of Cladophora glomerata2 along the east and north shorelines of the Great Lakes and St. Lawrence Seaway extends form just east of Montreal to Thunder Bay on Lake Superior. However, it does not occur at sites sampled in Georgian Bay, the North Channel or eastern Lake Superior. The dominant epiphytes on Cladophora throughout this range are the blue‐green algae, particularly Lyngbya diguetii, L. epiphytica and Chamaesiphon incrustans, which account for 53 to 90% of the cell density. The diatoms Cocconeis pediculus and Rhoicosphenia curvata contribute to much of the remaining density. The red alga Chroodactylon ramosum is a minor component of Cladophora epiphyton but is widespread in Lakes Ontario, Erie and Huron. Filament morphology, cell diameters and lengths of Chroodactylon are quite similar to those of marine forms. In addition, this alga has been reported to be quite tolerant of a wide range of salinities. Chroodactylon has been found in 33 freshwater sites throughout North America and 30 of these are from the Great Lakes or its drainage basin. Therefore, it appears possible that Chroodactylon, like Bangia atropurpurea, has originated in the Great Lakes by a migration from the Atlantic Ocean.
A UNIQUE MITOTIC VARIATION IN THE MARINE DINOFLAGELLATE OXYRRHIS MARINA (PYRROPHYTA)1
Authors: Triemer Richard E. 
Published: August 2007

ABSTRACTMitosis is described in the flagellate Oxyrrhis marina Dujardin and is compared in related genera. Dense plaques develop in the nuclear envelope at prophase and give rise to an intranuclear spindle. Some of the microtubules associate with the chromosomes while others extend across the nucleus. The basal bodies migrate toward the poles early in division and retain a position lateral to the nuclear poles throughout mitosis. Microtubules are not present between the nucleus and the basal bodies. The nucleolus is persistent and elongates throughout anaphase and telophase. Chromosomal separation is accomplished by sliding of non‐chromosomal microtubules and by elongation of the nuclear envelope rather than by shortening of the spindle microtubules. The nuclear envelope begins to constrict in the center early in anaphase. Continued constriction of the envelope and elongation of the nucleus leads to the formation of a dumbbell‐shaped nucleus by late telophase. Mitosis culminates by the constriction of the nucleus into two daughter nuclei. The taxonomic position of Oxyrrhis marina is discussed in light of these findings.
MICROSOURCES OF BIOLUMINESCENCE IN PYROCYSTIS FUSIFORMIS (PYRROPHYTA)1
Authors: Sweeney Beatrice M. 
Published: August 2007

ABSTRACTThe large dinoflagellate, Pyrocystis fusiformis Murray, emits biolumtnescence on stimulation with dilute acid. The bioluminescence can be seen in the light microscope to originate in a spherical region just distal to the nucleus during the day and appears as a persistent glow which can be localized in an orange‐brown sphere. At night, the bioluminescence, in response to stimulation, is a bright flash from microsources scattered throughout the cytoplasm. The orange sphere can no longer be seen nor does a bioluminescent glow originate from this central region on stimulation. This difference in the position of intracellular bioluminescence between day and night has allowed the identification in electron micrographs of structures which correspond to the source of bioluminescence during the day. Light is emitted from a spherical mass of vesicles which contain electron‐dense short rods with rounded ends, sometimes crossed by electron‐transparent narrow bands. At night, these vesicles can be recognized in the peripheral cytoplasm. It is proposed that these vesicles are the structural counterparts of the microsources of bioluminescence in P. fusiformis.
LIGHT REQUIREMENTS FOR MONOSPORE GERMINATION IN BANGIA ATROPURPUREA (RHODOPHYTA)1
Authors: Charnofsky Korene , Towill Leslie R. , Sommerfeld Milton R. 
Published: August 2007

ABSTRACTMonospore germination, in Bangia atropurpurea (Roth) C. Ag. [= B. fuscopurpurea (Dillw.) Lyngb.] is light‐dependent. In white light, the percent germination increases with increasing photon fluence rate until the response is saturated at 35 μmol · m−2· s−1. At a saturating photon fluence rate in an 18:6 h L:D cycle, 9 days are required for maximum germination. Green light is the most effective spectral region for monospore germination, although the process can occur in red and blue light if sufficiently high photon fluence rates are provided. Monospore germination and photosynthetic oxygen evolution are completely inhibited by DCMU at a concentration of 1 × 10−6 M. Germination is reduced in a low CO2 atmosphere and does not occur in the dark when glucose, maltose or inositol are supplied. It is concluded that photosynthesis is required for monospore germination.