bluuebunny/crossref_metadata_2025 huggingface dataset:
PHOSPHATE UPTAKE BY THE OCEANIC DINOFLAGELLATE PYROCYSTIS NOCTILUCA1
Authors: Rivkin Richard B. , Swift Elijah
Published: August 2007

Phosphate uptake by P‐replete and P‐depleted Pyrocystis noctiluca (Murray) Schütt grown at different ambient N:P ratios was multiphasic between 0.1 and 100 μM PO43‐. Within each of the kinetic phases, the saturated uptake rate (Vmax), but not the half saturation constant (Km) was affected by the cellular‐P status and light. Uptake rates in the dark were ca. 50% of that in the light and respiratory activity accounted for the observed basal uptake. The combination of multiphasic uptake, and the uncoupling of short term transient uptake from growth resulting in maximum specific uptake rates of 50 h−1 may help explain the abundance of P. noctiluca in oligotrophic regions.
DISTRIBUTION OF EDAPHIC DIATOMS IN A MISSISSIPPI SALT MARSH: A CANONICAL CORRELATION ANALYSIS1
Authors: Sullivan Michael J.
Published: August 2007

A canonical correlation analysis was performed to examine the degree to which edaphic diatom distribution in Graveline Bay Marsh, Mississippi could be related to environmental factors. It was possible to collapse the complex data base into two interpretable, orthogonal dimensions and to identify five distinct diatom communities. Diatom distribution on the marsh was primarily regulated by elevation and height of the overstory spermatophyte canopy. Although redundancy in the species data given the environmental data was relatively low (23% for the first two canonical variables), similar values were obtained for studies of benthic and planktonic diatoms in Yaquina Estuary, Oregon. The present study represents the first application of multivariate statistics to the study of salt marsh diatoms and demonstrates its usefulness in an environment where gradients are difficult to perceive.
STRUCTURE AND DEVELOPMENT OF THE CARPOSPOROPHYTE OF NEMALION HELMINTHOIDES (NEMALIONALES, RHODOPHYTA)1
Authors: Ramm‐Anderson Sue M. , Wetherbee Richard
Published: August 2007

Following fertilization, the carposporophyte of Nemalion helminthoides (Velley in With.) Batters differentiates into four distinct regions: the fusion cell, the sterile gonimoblast cells, the carposporangial mother cells and the carposporangia. The gonimoblast is formed by apically dividing, monopodial filaments of limited growth which may later become pseudodichotomous. Upon differentiation of a terminal carposporangium, a gonimoblast filament may continue to grow sympodially. A single carposporangial mother cell may produce carposporangia in several different directions as well as proliferate successive carposporangia within the sporangial walls that remain after carpospore liberation. As the carposporophyte matures, the gonimoblast initial, the stalk cell, the hypogynous and subhypogynous cells fuse. Except for the fusion cell, all cells of the carposporophyte show organelle polarity and contain a distally located, lobed chloroplast and proximal nucleus.
ASSESSING PHYSIOLOGICAL STRESS IN THALASSIOSIRA FLUVIATILIS (BACILLARIOPHYTA) AND DUNALIELLA TERTIOLECTA (CHLOROPHYTA) WITH DCMU‐ENHANCED FLUORESCENCE1
Authors: Sellner Kevin G. , Lyons Larry , Perry Elgin S. , Heimark Douglas B.
Published: August 2007

Exponentially growing cultures of Thalassiosira fluviatilis Hustedt and Dunaliella tertiolecta Butcher were exposed to 4 min temperature shocks of 5° to 20°C above ambient (20°C). Photosynthetic carbon fixation, changes in in vivo fluorescence and fluorescence on the addition of the herbicide DCMU (3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea) were measured over the subsequent 24 h. The fluorescence ratio (R, DCMU‐enhanced fluorescence/in vivo fluorescence) paralleled changes in photosynthesis over this period; both were significantly reduced (P < 0.05) by temperature shocks of +15° and +20° C, but +5° and +10° C treatments had no inhibitory effect on either relative to the control. The instantaneous response obtained with the fluorescence ratio indicates that the technique might be applicable to routine bioassay procedures and thus replace the time consuming methods now used for the estimation of 14C‐incorporation and growth rates.
PHYSIOLOGICAL VARIATION AND ELECTROPHORETIC BANDING PATTERNS OF GENETICALLY DIFFERENT SEASONAL POPULATIONS OF SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)1
Authors: Gallagher Jane C.
Published: August 2007

Clones of Skeletonema costatum (Grev.) Cl. isolated from Narragansett Bay, R.I., during different seasons were grouped according to their electrophoretic banding patterns. The growth rates, pg chlorophyll · cell−1, carbon uptake · cell−1· h−1, and carbon uptake · pg chl−1· h−1 were measured at 20°C, in a 14:10 h L:D cycle at 180 μE · m−2· s−1. Statistically significant sources of variation were found among groups of clones in growth rate, pg chl · cell−1, and carbon uptake · pg chl−1· h−1. It was concluded that there is a significant relationship between the physiological characteristics of clones isolated from populations in different seasons and patterns of genetic variation inferred from the electrophoretic studies. However, genetic diversity detected by banding patterns tends to underestimate the total genetic diversity in natural populations. The groups of clones most common in summer bloom populations had significantly higher growth rates, lower values of pg chl · cell−1, and higher rates of carbon uptake · pg chl−1· h−1 at 20°C than did the group of clones most common in winter bloom populations. However, differences among groups in these parameters at 20°C alone cannot account for the seasonal cycling of genetically variable populations of Skeletonema in Narragansett Bay. The range of growth rates among clones of this species is 0.1–5.0 divisions · d−1 under a single set of temperature and light conditions. Chlorophyll concentrations range from 0.2–1.7 pg chl · cell−1 and carbon uptake · pg chl−1· h−1 varies by a factor of 7 among clones. The range of physiological variation in this species means that it is difficult to use laboratory studies of single clones to analyze the responses of natural populations of Skeletonema.
STRUCTURE, LIFE HISTORY AND SYSTEMATICS OF RHOICOSPHENIA (BACILLARIOPHYTA). I. THE VEGETATIVE CELL OF RH. CURVATA1
Authors: Mann David G.
Published: August 2007

Rhoicosphenia Grun. has been placed by some authors in the monoraphid group with Achnanthes Bory and Cocconeis Ehrenb., and by others near Gomphonema Ehrenb. In order to clarify the systematic position of the genus, the morphology and anatomy of the vegetative cells of Rh. curvata (Kütz.) Grun. were investigated using light and electron microscopy. The structure and formation of the two types of valve are described, and the heterovalvy shown to be of a different type from that of the monoraphids; on the basis of raphe, valve and girdle structure a close relationship between these and Rhoicosphenia is unlikely. Rhoicosphenia shows many resemblances to Gomphonema but the types of pore occlusion present, coupled with apparently slight differences in the mucilage‐secreting structures and the girdle, suggest that classification in the same family is unwise. The cryptic asymmetry of the valves, and in particular of the raphe system, is noted and explained with reference to their formation; with respect to this asymmetry two configurations of the valves can occur (named cis and trans types) and the distribution of these in raphid genera is discussed briefly. In view of the lack of evidence in raphid diatoms supporting a classification of bands into copulae and pleurae, it is recommended that this practice be suspended.
ALGAL DISTRIBUTION IN A SMALL, INTERMITTENT STREAM RECEIVING ACID MINE‐DRAINAGE1
Authors: Lampkin Andrew J. , Sommerfeld Milton R.
Published: August 2007

Lynx Creek, a small intermittent creek in the Bradshaw Mountains of Arizona, is subjected to drainage from an abandoned copper mine. The mine‐drainage decreases the pH of the Creek about three units and greatly increases sulfate and heavy metal concentrations. Chemical recovery of the Creek occurs downstream through precipitation of metal hydroxides and dilution by tributaries. Changes in Creek chemistry are accompanied by changes in algal flora. Above the mine and downstream after substantial recovery, the flora is dominated by Tribonema affine4, Achnanthes spp., and Synedra ulna and several zygnematacean species. In the mine seep entering the Creek and in the Creek just below the seep the flora is reduced in species richness and dominated in abundance by Microthamnion kuetzingianum and Eunotia tenella.
TEMPERATURE EFFECTS ON SILICON LIMITED GROWTH OF THE LAKE MICHIGAN DIATOM STEPHANODISCUS MINUTUS (BACILLARIOPHYCEAE)1
Authors: Mechling Joyce A. , Kilham Susan Soltau
Published: August 2007

The effect of temperature on the silicon limited growth and nutrient kinetics of Stephanodiscus minutus Grun. was examined using batch and semicontinuous culture methods. Short‐term batch culture methods gave maximum growth rates which were essentially constant over the temperature range of 10° to 20°C (μ3= 0.71–0.80 d−1). The half‐saturation constant for growth (Ks) was significantly lowest at 10°C (Ks= 0.31 μM Si; 0.22–0.41), and higher at both 15°C (Ks= 1.03 μM Si; 0.68–1.47) and 20°C (Ks= 0.88 μM Si; 0.60–1.22). Two methods were used to evaluate the semicontinuous experiments. The Droop relationship showed that the minimum cell quota was about 1.50 × 10−7 nmol Si cell−1, but there was much overlap in the results at all three temperatures. The Monod growth relationship for the semicontinuous experiments gave estimates of Ks which were lowest at 15°C (Ks= 0.12 μM Si), and higher at 10°C (Ks= 0.68 μM Si) and 20°C (Ks= 1.24 μM Si), although 95% confidence intervals overlapped. The maximum growth rate estimates for the semicontinuous experiments were similar at 10° and 15°, and higher at 20°C, but the number of points used in making the calculations makes the results less reliable than those from batch cultures. Generally, there were no consistent significant differences in the silicon limited growth of S. minutus over the temperature range studied. Our values of Ks for S. minutus are the lowest recorded for a freshwater diatom, and are consistent with the distribution of this species in nature. Generally, this species becomes abundant in areas with high phosphorus loading and very low silicon levels (low Si:P loading rates). Stephanodiscus species are also fossil indicators of eutrophication in north temperate lakes.
PHYSIOLOGICAL RESPONSES OF ANABAENA VARIABILIS (CYANOPHYCEAE) TO INSTANTANEOUS EXPOSURE TO VARIOUS COMBINATIONS OF LIGHT INTENSITY AND TEMPERATURE1
Authors: Collins Carol D. , Boylen Charles W.
Published: August 2007

Light intensity and temperature interactions have a complex effect on the physiological process rates of the filamentous bluegreen alga Anabaena variabilis Kütz. The optimum temperature for photosynthesis increased with increasing light intensity from 10°C at 42 μE·m−2·s−1 to 35°C at 562 μE·m−2·s−1. The light saturation parameter, IK, increased with increasing temperatures. The maximum photosynthetic rate (2.0 g C·g dry wt.−1·d−1) occurred at 35°C and 564 μE·m−2·s−1. At 15°C, the maximum rate was 1.25 g C·g dry wt.−1·d−1 at 332 μE·m−2·s−1. The dark respiration rate increased exponentially with temperature. Under favorable conditions of light intensity and temperature the percent of extracellular release of dissolved organic carbon was less than 5% of the total C fixed. This release increased to nearly 40% under combinations of low light intensity and high temperature. A mathematical model was developed to simulate the interaction of light intensity and temperature on photosynthetic rate. The interactive effects were represented by making the light‐saturation parameters a function of temperature.
SCANNING ELECTRON MICROSCOPY OF CORALLINA AND HALIPTILON (CORALLINACEAE, RHODOPHYTA): SURFACE FEATURES AND THEIR TAXONOMIC IMPLICATIONS1
Authors: Garbary David J. , Johansen H. W.
Published: August 2007

Scanning electron microscopy of intergenicula in members of the subfamily Corallinoideae reveals two distinctive surface morphologies: a Corallina‐type (C‐type) with round to irregular cell outlines and round trichocyte bases, and a Jania‐type (J‐type) with elongate, polygonal cell outlines and elongate trichocyte bases with excentric pores. The surface results from the calcified lateral walls of the epithallial cells projecting up from around collapsed protoplasts. Since J‐type surfaces and trichocytes only occur in unequivocal members of the tribe Janieae—especially the genera Jania and Haliptilon, the presence of J‐type surfaces in questionable members of Corallina reveals that they in fact belong to Haliptilon. Thus the two surface types clarify previously difficult taxonomic distinctions between Haliptilon and Corallina and allow identification to genus from purely vegetative material. Seventeen new combinations in Haliptilon are proposed. These results have considerable biogeographic implications with tropical species found to belong to Haliptilon, and Corallina sensu stricto being recognized primarily as a temperate and cold water genus.
INTRASPECIFIC COMPARISONS OF NITRATE UPTAKE IN THREE MARINE DIATOMS1
Authors: Romeo Anthony J. , Fisher Nicholas S.
Published: August 2007

Short‐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

Sporophytes 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

The 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

Reproduction 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

The 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

Medium 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

New 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

Homothallic 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

Concentrates 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

The 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

The, 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

The 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

Internal 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

The 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

A 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

The 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

Mitosis 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

The 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

Monospore 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.
ULTRASTRUCTURE OF EARLY DEVELOPMENT IN THE FEMALE REPRODUCTIVE SYSTEM OF POLYSIPHONIA HARVEYI BAILEY (CERAMIALES, RHODOPHYTA)1
Authors: Broadwater Sharon T. , Scott Joe
Published: August 2007

Prefertilization and immediate postfertilization development in the female reproductive branch of Polysiphonia harveyi (Bailey) was studied with the electron microscope. Results pertaining to prefertilization morphology and development are consistent with those established in earlier light microscopic studies, but several unexpected ultrastructural characteristics were discovered. The mature carpogonium was found to have double membrane‐bound vacuoles of nuclear origin and the carpogonial nucleus contained a nucleolus with a distinctive crystalline lattice. Trichogynes lacked a nucleus. Of particular interest was the discovery of a highly structured channel of smooth endoplasmic reticulum (SER) which extended uninterrupted, except for pit connections, through the carpogonial branch. It is suggested that the message of fertilization is conducted through the SER channel from the carpogonium to the support cell. Few observations were made on postfertilization branches, but evidence of direct fusion between the carpogonium and auxiliary cell was fairly conclusive. Pit plugs in the female branch were found to be of three morphological types differing by the presence and number of pit membranes. We have designated these plugs Type I–III since differential functioning was not fully ascertained. Our data suggest that pit membranes may serve to stabilize the plug and that those plugs without membranes are more readily dismantled to allow cytoplasmic continuity between cells.
TRANSPORT OF AMINO ACIDS BY THE SOIL ALGA STICHOCOCCUS BACILLARIS1
Authors: Carthew Richard W. , Hellebust Johan A.
Published: August 2007

The green alga Stichococcus bacillaris Naeg. is able to take up at least eleven amino acids. All of these except glutamic and aspartic acids are transported by carrier systems that obey saturation kinetics. The acidic amino acids enter the cell by passive diffusion. Michaelis‐Menten parameters (Ks and Vmax) were calculated for several amino acids. All obey simple Michaelis‐Menten behavior except for 2‐methylalanine and leucine which may have double carrier systems of different affinities. Interactions between pairs of amino acids suggest that there is at least one carrier system specific for basic amino acids and probably several systems specific for neutral amino acids. Further analysis of neutral amino acid interactions reveal that the uptake of several amino acids is incompletely inhibited by competitor uptake at infinite concentration. The simplest interpretation of the data is the operation of three carrier systems for neutral amino acids, one of which has higher affinity and broader specificity than the other two. The amino acid carrier systems appear to operate by an active mechanism. The metabolic poison DCCD inhibits uptake up to 99%. The capacities of the neutral amino acid carrier systems are increased when cells are grown in medium containing suboptimal concentrations of nitrogen.
DISTRIBUTION OF CARBON AMONG PHOTOSYNTHETIC END‐PRODUCTS IN PHYTOPLANKTON OF THE EASTERN CANADIAN ARCTIC1
Authors: William K. W. Li  , Platt Trevor
Published: August 2007

The distribution of 14C among photosynthetic end‐products was examined in eastern Canadian arctic phytoplankton, with particular emphasis on the synthesis of lipids. The pattern of 14C distribution for phytoplankton at each of three depths was generally similar among populations from 12 stations. About 18% of the total 14C fixed was incorporated into lipids. At one station, phytoplankton were experimentally subjected to temperature and light conditions different from those in situ: lipid‐14C did not exceed 30% of total 14C fixed within the temperature range ‐1.0 to 6.0° C and irradiance range 1 to 700 W · m−2. It is suggested that low temperatures and low light intensities, even when, maintained for prolonged periods, are not fully sufficient conditions for eliciting high relative rates of 14C incorporation into lipids. It is possible that differences in species composition may be a factor accounting for different patterns of 14C distribution between north and south polar phytoplankton under apparently similar environmental conditions.
THE IDENTITY AND REPRODUCTIVE STRUCTURES OF A MISPLACED SOLENOPORA (RHODOPHYCOPHYTA) FROM THE ORDOVICIAN OF SOUTHWESTERN OHIO AND EASTERN INDIANA1
Authors: Blackwell Will H. , Marak Joe H. , Powell Martha J.
Published: August 2007

A study of certain fossil, limestone‐forming algae in upper Ordovician beds (Elkhorn and Whitewater Formations of the Richmond Subseries of the Cincinnati Series) in southwestern Ohio and adjacent eastern Indiana culminated with the conclusion that an organism originally described as a sponge, and later placed in the genus Girvanella Nicholson and Etheridge (Cyanochloronta), should in fact be transferred to the genus Solenopora Dybowski (Rhodophycophyta), A calcified reproductive layer was discovered in one of the specimens sectioned. These structures are interpreted as either sporangia or as sporangial chambers, and occur in a sorus rather than a conceptacle type of arrangement. This find has an important bearing on the phylogenetic history of the Solenoporaceae.
STRUCTURE OF THE ANISOGAMETES OF THE GREEN SIPHON PSEUDOBRYOPSIS SP. (CHLOROPHYTA)1
Authors: Roberts Keith R. , Stewart Kenneth D. , Mattox Karl R.
Published: August 2007

The fine structure of the male and female gametes of Pseudobryopsis, particularly that of the flagellar apparatus, is compared with that of swarmers of other green algae. There is general similarity, with differences in detail, to the Ulvales and other green siphons that have been studied. The similarities include overlapping basal bodies, the capping plate type of connective between basal bodies, terminal caps, and system II fibrous roots (rhizoplasts). The capping plate of the female gamete differs from that in other green siphons and the Ulvales in form and in the presence of a faint striation. A diagram illustrating the actual arrangement of the components of the flagellar apparatus is given, along with a discussion of the fact that the mirror image of the true arrangement has been given in some reports on ulvaphycean algae.
PHOTOSYNTHETIC RESPONSE OF LAKE PLANKTON TO COMBINED NITROGEN ENRICHMENT1
Authors: Lean D. R. S. , Murphy T. P. , Pick F. R.
Published: August 2007

The complex interplay between photosynthesis and the uptake of nitrogen was investigated in samples from five lakes of different size and trophic state. When enriched with 15NH4+, the photosynthetic rate was often reduced for 4–5 h in samples believed to be nitrogen deficient. This implies that energy was reallocated from photosynthesis to the uptake and assimilation of N. Stimulation in C uptake at low levels of NH4+ enrichment was followed by a progressive decline with further NH4+ enrichment. On other occasions when ambient NH4+ was undetectable, nutrient regeneration by zooplankton supplied a significant fraction of the required nitrogen. At these times and when the plankton had sufficient available N, there usually was no change in photosynthetic rate with either NH4+ or NO3−enrichment. Typically, little NO3− was taken up and no photosynthetic response was observed. On two occasions, however, the uptake of NO3− was significant due to high NO3− and low NH4+ levels early in the season. At one of these times there was a reduction in photosynthesis with NO3− enrichment. A further complication was observed when photosynthesis decreased with NH4+ enrichment but increased with NO3− enrichment despite negligible NO3− uptake. These observations illustrate that the complex metabolism of these two nitrogen sources is not fully understood. At optimum light intensity, C:N uptake ratios, even under NH4+ enrichment, are only sufficient to maintain the cellular C:N ratio unless much of the fixed C is respired or excreted. Three observations suggest that photosynthesis and N uptake are not coupled, (i) Photoinhibition of C uptake, but not N uptake was observed when low light adapted populations are exposed to high light conditions, (ii) The light intensity for maximum N uptake was slightly less than that for carbon. (iii) Dark N uptake was always near 50% of the maximum rate in the light whereas the C uptake was near 2% of Popt. Certainly, there is an interconnection because dark C uptake was enhanced by NH4+ enrichment.
EFFECTS OF GRAZERS AND ALGAL COMPETITORS ON FUCOID COLONIZATION IN TIDE POOLS1
Authors: Lubchenco Jane
Published: August 2007

In New England, fucoids are conspicuously absent from midlittoral sheltered tide pools, though abundant on adjacent emergent rocks. Experimental removal of either herbivores or potential algal competitors from mid littoral tide pools failed to result in the establishment of fucoids. However, removal of both groups together resulted in the establishment of Fucus vesiculosus L. Once established, some individuals persisted for up to three years. These grew well, were of normal, healthy appearance and reproduced. The herbivores removed were Littorina littorea, L. obtusata and Acmaea testudinalis. Algae removed were Chondrus crispus Stackhouse, Ulva lactuca L., Rhizoclonium tortuosum Kützing, Spongomorpha spinescens Kützing, Polysiphonia sp., Dumontia incrassata (O.F. Muller) O. Kuntze and Scytosiphon lomentaria (Lyngbye) Link. It is concluded that absence of fucoids from mid littoral, protected pools is due to the joint action of herbivores and algal competitors and not to possible deleterious factors associated with constant submersion.
UPTAKE OF GUANINE BY THE DIATOM, PHAEODACTYLUM TRICORNUTUM1
Authors: Shah N. , Syrett P. J.
Published: August 2007

Nitrate‐cultured cells of Phaeodactylum tricornutum Bohlin lack the ability to take up guanine but can do so after a period of nitrogen deprivation, i.e. photosynthesis in nitrogen‐free medium. Maximum rate of uptake occurred after 24 h of nitrogen deprivation. The development of ability to take up guanine required CO2 fixation and was prevented by cycloheximide, ammonium or nitrate. The guanine taken up accummulated in the cells almost entirely as a compound which is probably methylated hypoxanthine. Guanine uptake was dependent upon metabolism and exhibited Michaelis‐Menten like kinetics with a half‐saturation value of 0.48 ± 0.05 μM guanine and a maximum uptake rate for guanine of ca. 200 nmol · 10−8 cells · h−1. Rate of uptake increased hyperbolically with Na+ concentration, with 8.25 mM Na+ supporting half‐maximal rate, and it was inhibited by K+ ions.
Channel Coordination for a Supply Chain with a Risk‐Neutral Manufacturer and a Loss‐Averse Retailer*
Authors: Wang Charles X. , Webster Scott
Published: August 2007

This articles considers a decentralized supply chain in which a single manufacturer is selling a perishable product to a single retailer facing uncertain demand. It differs from traditional supply chain contract models in two ways. First, while traditional supply chain models are based on risk neutrality, this article takes the viewpoint of behavioral principal–agency theory and assumes the manufacturer is risk neutral and the retailer is loss averse. Second, while gain/loss (GL) sharing is common in practice, there is a lack of analysis of GL‐sharing contracts in the supply chain contract literature. This article investigates the role of a GL‐sharing provision for mitigating the loss‐aversion effect, which drives down the retailer order quantity and total supply chain profit. We analyze contracts that include GL‐sharing‐and‐buyback (GLB) credit provisions as well as the special cases of GL contracts and buyback contracts. Our analytical and numerical results lend insight into how a manufacturer can design a contract to improve total supply chain, manufacturer, and retailer performance. In particular, we show that there exists a special class of distribution‐free GLB contracts that can coordinate the supply chain and arbitrarily allocate the expected supply chain profit between the manufacturer and retailer; in contrast with other contracts, the parameter values for contracts in this class do not depend on the probability distribution of market demand. This feature is meaningful in practice because (i) the probability distribution of demand faced by a retailer is typically unknown by the manufacturer and (ii) a manufacturer can offer the same contract to multiple noncompeting retailers that differ by demand distribution and still coordinate the supply chains.