bluuebunny/crossref_metadata_2025 huggingface dataset:
AMMONIUM, NITRATE, PHOSPHATE, AND INORGANIC CARBON UPTAKE IN AN OLIGOTROPHIC LAKE: SEASONAL VARIATIONS AMONG LIGHT RESPONSE VARIABLES1
Authors: Dodds Walter K. , Priscu John C.
Published: October 2004

The dependence of substrate saturated uptake of 15NH4+, 15NO3−, 32PO43−, and 14CO2 on photosynthetic photon flux density (PPFD or photsynthetically active radiation, 400–700 nm) was characterized seasonally in oligotrophic Flathead Lake, Montana. PO43− uptake was not dependent upon PPFD at any time of the year, whereas NH4+, NO3−, and CO2 uptake were consistently dependent on PPFD over all seasons. Maximal rates of NH4+, NO3− and CO2 uptake usually occurred near 40% of surface PPFD, which corresponded to about 5 m in the lake; inhibition was evident at PPFD levels greater than 40%. NH4+, NO3− and PO43− were incorporated in the dark at measurable rates most of the year, whereas dark CO2 uptake was always near 0 relative to light uptake. CO2 and NO3− uptake were more strongly influenced by PPFD than was NH43− uptake. The PPFD dependence of PO43−, NH4+, NO3− and CO2 uptake may affect algal growth and nutrient status by influencing the balance in diel and seasonal C:N:P uptake ratios.
A CIRCADIAN RHYTHM IN THE LONG‐DAY PHOTOPERIODIC INDUCTION OF ERECT AXIS DEVELOPMENT IN THE MARINE RED ALGA NEMALION HELMINTHOIDES1,2
Authors: Cunningham Eamon M. , Guiry Michael D.
Published: October 2004

Two isolates of Nemalion helminthoides from the west coast of Ireland showed a heteromorphic life history in which tetraspores formed under short‐day conditions on uniaxial, prostrate tetrasporophytes gave rise to uniaxial, prostrate growths similar in morphology to the tetrasporophytes. The induction of multiaxial, erect axes on tetraspore‐derived plants was a long‐day photoperiodic response. At 11°C, 16:8 h LD, nitrate concentration in the enriched seawater medium had little effect on the numbers of erect exes formed. Induction of erect axes occurred only in daylengths ≥ 12 h, mainly between 7–13° C, and the critical daylength, which generally lies between 14 and 16 h, changed with temperature. Night‐breaks (NB) of 1 h light in the middle of 16 h night were ineffective in the promotion of erect axis formation, and day‐breaks (DB) of 1 h darkness in the middle of a 16 h day did not inhibit axis formation. Neither continuous light nor NB of 1–1.5 h given at various times during the dark period of an 8:16 h LD cycle promoted the formation of erect axes. At 9° C, equivalent photon exposures (0.69 and 0.34 mol·m−2) at two different instantaneous photon flux densities resulted in erect axis formation only in the 14 h, 16 h and DB regimes. Photoregimes of 16 h light in combination with dark cycles of various lengths resulted in the maximal promotion of the formation of erect axes in diurnal (22–24 h) and bi‐diurnal (44–48 h) cycles, a diminishing response in non‐diurnal cycles greater than 24 and 48 h, and a minimal response at 32 h. These data show that the formation of erect axes is a long‐day photoperiodic response and provide further evidence for a connection between endogenous circadian rhythms and long‐day photoperiodic responses.
NEW GENERA AND SPECIES OF CERAMIACEAE (RHODOPHYTA) FROM THE SOUTHEASTERN UNITED STATES1
Authors: Searles Richard B. , Schneider Craig W.
Published: October 2004

Five Ceramiaceae (Rhodophyta) are reported from the offshore waters of the southeastern, warm temperate coast of the United States. These include two new monotypic genera,Calliclavula trifurcateSchneider in the Griffithsieae andNwynea grandisporaSearles in the Sphondylothamnieae, and three new species,Callithamniella silvaeSearles,Ptilothamnion occidentaleSearles, andLejolisia expositaSchneider et Searles.
CYTOCHEMICAL STUDIES ON PROCHLOROPHYTES: LOCALIZATION OF DNA AND RIBULOSE 1,5‐BISPHOSPHATE CARBOXYLASE‐OXYGENASE1
Authors: Swift Hewson , Leser George P.
Published: October 2004

We studied the distribution of the DNA‐containing region and the ribulose 1,5‐bisphosphate carboxylase‐oxygenase (RuBisCo) content of polyhedral bodies in three different prochlorophyte cell types in a search for broad evolutionary affinities of these chlorophyll b‐containing prokaryotes. DNA was localized by DAPI staining and electron microscopy utilizing monoclonal anti‐DNA antibody 2C‐10 plus a secondary antibody labeled with colloidal gold. Antibodies against the large RuBisCo subunit from a higher plant raised in rabbits were used to localize RuBisCo in polyhedral bodies. We studied Prochloron Lewin cells from two different didemnid ascidian hosts (Lissoclinum patella and Didemnum molle) collected in Palau, West Caroline Islands, and cells of Prochlorothrix hollandica Burger‐Wiersma, Stal, and Mur grown in laboratory culture. Cells of the blue‐green alga Anabaena 7120 were studied for comparison. The DNA distribution was markedly different in the two Prochloron cell types. The thylakoids in cells from L. patella were concentrically arranged around a large central vacuole; the DNA‐containing stromal areas appeared in thin sections as a concentric arcs between the thylakoid stacks. The central vacuole was lacking in cells from D. molle, and the thylakoid stacks and strands of DNA‐containing stroma showed a more haphazard arrangement. In the filamentous Prochlorothrix the DNA‐containing stroma was largely limited to a central nucleoid structure running the length of the cell. Although the DNA arrangements in Prochloron might be considered “chloroplast‐like” since DNA‐containing stroma is distributed, as in chloroplasts, in scattered sites among photosynthetic membranes, this is not so in Prochlorothrix, where there is an axial nucleoid, as in many filamentous cyanobacteria. Our anti‐RuBisCo antibodies were selectively bound to the polyhedral bodies of all three cell types, indicating that Prochloron and Prochlorothrix, like many other autotrophic prokaryotes, possess typical carboxysomes.
TEMPERATURE EFFECTS ON SILICON‐ AND PHOSPHORUS‐LIMITED GROWTH AND COMPETITIVE INTERACTIONS AMONG THREE DIATOMS1
Authors: van Donk Ellen , Kilham Susan Soltau
Published: October 2004

Three diatom species, Stephanodiscus hantzschii (Ehr.) Grun., Asterionella formosa Hass. and Fragilaria crotonensis Kitt. Hass. were isolated from Lake Maarsseveen where they are dominant and show a successional sequence. The physiological responses of each species to temperature and limitation by silicon and phosphorus were determined over the temperature range of 5° to 20° C using short‐term batch culture methods. Stephanodiscus hantzschii had higher maximum growth rates than the other two species at all temperatures, and the maximum growth rates of all species increased with increasing temperature. Temperature affected not only maximum growth rates but also half‐saturation constants (Ks) and the minimum cell quotas. S. hantzschii had low silicon requirements for growth under Si‐limiting conditions, and A. formosa and F. crotonensis had higher and nearly identical silicon requirements. The Ks values for silicon for S. hantzschii were essentially constant from 5° to 20° C but varied greatly for the other two species. A. formosa had the lowest requirements for growth under phosphorus limitation, F. crotonensis was intermediate and S. hantzschii had the highest growth requirements for phosphorus. The K1 values for phosphorus were constant over the temperature range for both A. formosa and F. crotonensis and were much higher and variable for S. hantzschii.

Nutrient competition experiments were performed in continuous cultures at four temperatures and various Si:P ratios. The results generally, but not always, confirmed the predictions based on the Monod relationships for each species. Results not in agreement with predictions were usually because of similar physiological properties of A. formosa and F. crotonensis or because of decreased loss rates for F. crotonensis due to wall growth. In cultures with all three species phosphorus‐limited (Si:P > 75), A. formosa often dominated as predicted, although F. crotonensis was sometimes the most abundant species. As predicted, S. hantzschii never dominated at high Si:P ratios. At intermediate Si:P ratios when A. formosa and F. crotonensis were both Si‐limited and S. hantzschii P‐limited, all three species coexisted because A. formosa and F. crotonensis have almost identical silicon requirements, although sometimes F. crotonensis was more abundant than predicted. At 10°C the results agreed best with the predictions; A. formosa dominated at high Si:P ratios and S. hantzschii dominated as predicted at low Si:P ratios when all three species were Si‐limited.
PROTEIN TURNOVER AND HETEROCYST DIFFERENTIATION IN THE CYANOBACTERIUM ANABAENA VARIABILIS1
Authors: Thiel Teresa
Published: October 2004

Under conditions of starvation for fixed nitrogen, cells of the filamentous cyanobacterium Anabaena variabilis Kütz, degrade much of their protein prior to heterocyst differentiation. Cells starved for a source of fixed nitrogen initially degraded about 2% of their protein per hour; by 24 h after nitrogen stepdown about 40% of the protein was degraded. Most of the acid‐soluble radiolabeled material was excreted into the medium. Proteolysis was completely inhibited by chloramphenicol, by cyanide, or in the dark, hut was only partially inhibited in the presence of dichlorophenyl dimethylurea. Methionine sulfoximine (MSX) (an inhibitor of glutamine synthetase) in the presence of ammonia caused heterocysts to form. MSX treated cells degraded protein; however, the amount of protein degraded was much less than in cells starved for ammonia. Glutamine, which can serve as a nitrogen source for this strain, did not prevent starvation‐induced proteolysis and did not prevent the differentiation of heterocysts.
MONOCLONAL ANTIBODIES SPECIFIC FOR SULFATED POLYSACCHARIDES ON THE SURFACE OF MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1
Authors: Eardley Diane D. , Sutton Celia W. , Hempel William M. , Reed Daniel C. , Ebeling Alfred W.
Published: October 2004

One of the principal polysaccharides in the cell wall of brown algae is fucoidan, a highly branched polymer of 1,2‐fucose with a sulfate group on the fourth carbon. In this report, we describe a set of monoclonal antibodies generated to the cell walls of gametophytes of the kelp, Macrocystis pyrifera (Linnaeus). C. Agardh. Ascites fluids of a set of four antibodies with specificity for the cell wall were purified by filtration chromatography. Each of these antibodies was specifically reactive with fucoidan, and one of the antibodies cross‐reacted with ascophyllan, which is a xyloglycuronan. The antibodies reacted in an immunofluorescence assay with surface determinants on the gametophytes of both Macrocystis pyrifera and Pterygophora californica Ruprecht which belong to different families in the order Laminariales. One of the antibodies (3H8) was further characterized for antigen fine specificity using an enzyme immunoassay. This antibody was specific for sulfate determinants present on fucoidan and related polysaccharides. Orientation of the sulfate was an important element in antibody specificity. Immunofluorescence microscopy carried out during the first four days of development in Pterygophora showed that the antigenic determinant recognized by the 3H8 antibody was present on spore capsules (embryospores) as well as the developing gametophyte. These results show that a sulfated epitope on fucoidan is present on the surface of the gametophyte shortly after germination and that it persists during the early stages of development. Our results indicate that any immunological differences between the morphologically similar gametophytes of the two helps are more likely to be quantitative than qualitative. Such differences may reflect differential mobilization of fucans during the process of germination and early development.
COMPARATIVE ANALYSIS OF THE DINOFLAGELLATE FLAGELLAR APPARATUS IV. GYMNODINIUM ACIDOTUM1
Authors: Farmer Mark A. , Roberts Keith R.
Published: October 2004

Gymnodinium acidotum Nygaard is a freshwater dinoflagellate that is known to harbor a cryptomonad endosymbiont whose chloroplasls give the organism an overall blue‐green color. The ultrastructure of G. acidotum was examined with particular attention being given to the three dimensional nature of the flagellar apparatus. The fiagellar apparatus is composed of two functional basal bodies that are slightly offset and lie at an angle of approximately 90° to one another. As in other dinoflagellates the transverse basal body is associated with a striated, fibrous root that extends from the proximal end of the basal body to the transverse flagellar opening. At least one microtubular root extends from the proximal end of the transverse basal body, and a multi‐membered longitudinal microtubular root is associated with the longitudinal basal body. The most striking feature of the flagellar apparatus of G. acidotum is the large fibrous connective that extends from the region of the proximal ends of the basal bodies to the cingulum on the dorsal side of the cell. A similar structure has been reported from only one other dinoflagellate, Amphidinium cryophilum Wedemayer, Wilcox, and Graham. The presence of this structure as well as similarities in external morphology suggest thai these two species may be more closely related to each other than either is to other gymnodinioid taxa. The taxonomic importance of dinoflagellate flagellar apparatus components is discussed.
FINE STRUCTURE OF THE FLAGELLAR APPARATUS OF DINOBRYON CYLINDRICUM (CHRYSOPHYCEAE)1
Authors: Owen Heather A. , Mattox Karl R. , Stewart Kenneth D.
Published: October 2004

The three‐dimensional structure of the flagellar apparatus of Dinobryon cylindrioum Imhof. (UTEX no. LB 2266) was determined using serial section reconstruction. Four microtubular rootlet systems (R1, R2, R3, and R4)and a rhizoplast are present, following the general pattern found in other chrysophytes. The R1 rootlet, containing seven microtubules, originates at the basal body of the long flagellum that bears mastigonemes (F1). The R1 rootlet forms an arc which curves in clockwise direction (when viewed from the anterior end of the cell) approximately halfway around the pit from which the short smooth flagellum (F2) emerges. Numerous microtubules cascade from the exterior‐facing side of this rootlet to the tail of the cell. The R2 rootlet originates between the F1 and F2 basal bodies, is attached to the F1 basal body by a fibrous connection, and forms a clockwise arc above the R1 rootlet. This rootlet extends approximately one quarter of the way around the pit. The R3 rootlet system originates as a trough‐shaped band of six microtubules spanning the distance between the proximal ends of the F1 and F2 basal bodies. The six‐membered rootlet splits into two parts, designated R3 and R3. Both parts circle the pit in counter‐clockwise direction, pass beneath the F2 basal body, and descend into the cell alongside the chloroplast. The R4 rootlet originates in fibrous material, passes diagonally over the top of the F2 basal body, forms a clockwise loop at least three quarters of the way around the pit to the interior of the R3 and R3 rootlets, and ends in the cytoplasm.

Similarities of rootlet origins and other details of the flagellar apparatus of D. cylindricum with those of other heterokont organisms reinforce the idea that these organisms are phylogenetically related.
ABSOLUTE CONFIGURATION OF THE FLAGELLAR APPARATUS OF BIFLAGELLATE ZOOSPORES OF ENTEROMORPHA FLEXUOSA SSP. PILIFERA (ULVOPHYCEAE, CHLOROPHYTA)1
Authors: Leonardi Patricia I. , Cáceres Eduardo J.
Published: October 2004

The absolute configuration of the flagellar apparatus of biflagellate zoospores of Enteromorpha flexuosa (Wulfen ex Roth.) J. Agardh ssp. pilifera (Kütz.) Bliding was determined. Viewed from the anterior of the cell, the flagellar apparatus shows 180° rotational symmetry with a counter‐clockwise absolute orientation of its components. In longitudinal sections, the posteriorly directed basal bodies form an angle of about 170°–180° to one another. A reduced striated distal fiber connects the two basal bodies. The cruciate microtubular rootlet system has a 4–2–4–2 alternation pattern. Striated microtubule‐associated components (SMACs or system I‐fibers) and rhizoplasts (or system II fibers) accompany the two‐membered rootlets. Striated bands connect the proximal sheaths with the four‐Membered rootlets. The bilobate terminal caps do not completely cover the proximal ends of the basal bodies. This is the first ultrastructural study of biflagellate zoospores in a member of the Ulvales.
SEA ICE DIATOMS (BACILLARIOPHYCEAE) OF THE CANADIAN ARCTIC. I. THE GENUS STENONEIS1
Authors: Poulin Michel
Published: October 2004

Ice diatom assemblages in the Canadian Arctic are dominated by the Naviculaceae, a family which includes the genus Stenoneis Cleve. A taxonomic history of S. inconspicua var. baculus (Cleve) Cleve (including type material of Navicula baculus Cleve) is presented with morphological data including the first SEM views of the genus. Stenoneis inconspicua var. baculus was compared with S. obtuserostrata (Hustedt) comb. nov. (basionym: Navicula obtuserostrata Hustedt). In the SEM, external, short, flattened siliceous ridges were revealed beside the proximal parts of the raphe branches and central pores. This may be a significant taxonomic feature of the genus. Valves of S. inconspicua var. baculus ranged from 40–103 μm in length, 7–11 μm in width and had 17–20 striae in 10 μm, whereas valves of S. obtuserostrata were shorter (27–53 μm), narrower (6–7.5 μm) and more finely striated (24–30 in 10 μm). Both taxa have a circumpolar Arctic distribution.
SYSTEMATIC ANALYSIS OFSPHAEROPLEA(CHLOROPHYCEAE)1
Authors: Buchheim Mark A. , Nickrent Daniel L , Hoffman Larry R.
Published: October 2004

A systematic investigation of the genusSphaeropleawas conducted using cladistic analyses of both structural and isozyme characters for the same set of taxa. The structural data were not able to fully resolve some of the taxa while the isozyme data did produce a tree in which all nodes were supported by data. The structural characters were relatively consistent with one another, whereas the isozyme characters were much less internally consistent. Results from independent, cladistic analyses of both data sets support the concept that among thoseSphaeropleaspecies investigated,S. fragilisBuchheim et Hoffman had an early divergence. The two data sets differed primarily in that the structural data support monophyly of the genusSphaeropleaand the isozyme data do not. The greater relative consistency of the structural data suggests better support for trees inferred from its analysis. Furthermore, searches for character congruence between the two data sets revealed isozyme data which support monophyly of the genusSphaeroplea, but had been overwhelmed by conflicting isozyme characters.
PHYLOGENY OF GRACILARIA LEMANEIFORMIS (RHODOPHYTA) BASED ON SEQUENCE ANALYSIS OF ITS SMALL SUBUNIT RIBOSOMAL RNA CODING REGION1
Authors: Bhattacharya Debashish , Elwood Hille J. , Goff Lynda J. , Sogin Mitchell L.
Published: October 2004

The small subunit ribosomal RNA (rRNA) sequence of Gracilaria lemaneiformis Bory Weber‐van Bosse was inferred from analysis of rRNA coding regions that were amplified by the polymerase chain reaction method. Comparison of the G. lemaneiformis small subunit rRNA to homologous genes of diverse eukaryotes demonstrated that the red algal divergence was nearly simultaneous with the separation of plants, fungi, animals and many other protist lineages. This result conflicts with those of 5S rRNA sequence and plastid based phytogenies which suggest that red algae represent an early divergence in the eukaryotic line of descent. Further, algae appear to be of polyphyletic origin and red algae are unrelated to higher fungi.
VARIATION IN DCMU‐ENHANCED FLUORESCENCE RELATIVE TO CHLOROPHYLL A: CORRELATION WITH THE BROWN TIDE BLOOM1
Authors: Keller Aimee A. , Rice Robin L.
Published: October 2004

DCMU–enhanced fluorescence and extracted chlorophyll a were simultaneously measured in Narragansett Bay, Rhode Island and the MERL (Marine Ecosystems Research Laboratory) mesocosms during the 1985 brown tide bloom. Marked differences in the relationship between these variables were observed as the phytoplankton community shifted from dominance by picoalgae to diatoms. The fluorescence to chlorophyll a ratio was significantly (P< 0.05) higher in the mesocosms and the bay when the brown tide species (Aureococcus anophagefferens Hargraves et Sieburth) dominated the phytoplankton community compared with other taxa. Although several factors could have affected the relationship we believe the high ratios are related to the pigment composition and/or small size of the brown tide organism.
UNCOUPLING OF VARIOUS MEASURES OF GROWTH IN ULVA ROTUXDATA(CHLOROPHYTA) FOLLOWING A LARGE DECREASE IN IRRADIANCE1
Authors: Henley William J.
Published: October 2004

A vegetative clone of the chlorophyte macroalga Ulva rotundata Blid. was maintained in an outdoor continuous flow system and subjected to a large decrease in irradiance. Specific growth rates based on changes in fresh (μFW) and dry weight (μDW) and surface area (μSA) were determined using precut disks over the 24 h following a post‐sunset transfer from full sunlight (100% I0) to 9% I0 All three measures of growth rate were approximately equivalent for untransferred control plants at either limiting (9%) or saturating (100%)I0. Transferred disks exhibited μFW and μSA which were slightly lower than 100%I0 controls and much higher than 9% I0 controls; μDW was nearly identical for transferred disks and 9% I0 controls. Cell size was unchanged following transfer, indicating that surface area changes reflected a proportional increase in cell number. Cell division therefore continued at a high rate for one day following transfer of U. rotundata to irradiances which are subsaturating for photosynthesis (indicated by μDw). Starch reserves were largely depleted, and the C/N ratio decreased during this period.
FUNGAL CONTROL OF POPULATION CHANGES OF THE PLANKTONIC DIATOM ASTERIONELLA FORMOSA IN A SHALLOW EUTROPHIC LAKE1
Authors: Kudoh Sakae , Tokahashi Masayuki
Published: October 2004

Parasitic fungi infected an Asterionella formosa Hass. population for 10 months of the year, during which time the population density of the alga was over 100 cells‐L−1. High injection rates of more than 20% of the cells were observed between February and July except on a few occasions such as late April and late June. Mortality of infected diatom cells was temperature dependent in dialysis tube culture experiments; the loss rate of field populations due to fungal injection also was affected by temperature. Loss rates of diatom cells were negligibly small m February even though infection percentages were more than 20%, but increased toward summer with an increase m temperature. High infection percentages and correspondingly high loss rates (e.g. 0.3 d−1) occurred periodically during the summer. The results suggest that this type of host‐parasite interaction is an important control of algal population size in natural waters.
STRUCTURE AND CHEMISTRY OF A NEW CHEMICAL RACE OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE) THAT PRODUCES LYCOPADIENE, A TETRATERPENOID HYDROCARBON1
Authors: Metzger Pierre , Allard Béatrice , Casadevall Eliette , Berkaloff Claire , Couté Alain
Published: October 2004

New strains of the hydrocarbon rich alga Botryococcus braunii Kützing were isolated from water samples collected in three tropical freshwater lakes. These strains synthesize lycopadiene, a tetraterpenoid metabolite, as their sole hydrocarbon. The morphological and ultrastructural characteristics of these algae are similar to those reported for previously described strains which produce either alkadienes or botryococcenes. The pyriform shaped cells are embedded in a colonial matrix formed by layers of closely appressed external walls: this dense matrix is impregnated by the hydrocarbon and some other lipids. We believe the new strains synthesizing lycopadiene form a third chemical race in B. braunii, besides the alkadiene and botryococcene races, rather than a different species.

Like the other two types of hydrocarbons, lycopadiene was produced primarily during the exponential and linear growth phases. The major fatty acid in the three races was oleic acid. This fatty acid was predominant in the alkadiene race; palmitic and octacosenoic acid also were present in appreciable amounts in the three races. Cholest‐5‐en‐3β‐ol, 24‐methylcholest‐5‐en‐3β‐ol and 24‐ethylcho‐lest‐5‐en‐3β‐ol occurred in the three races; three unidentified sterols also were detected in the lycopadiene race. Moreover, the presence of very long chain alkenyl‐phenols in the lipids of algae of the alkadiene race was not observed in the botryococcene and lycopadiene races. Of the polysaccharides released in the medium, galactose appeared as a primary component: it predominated in the botryococcene race. The other major constituents were fucose for the alkadiene race and glucose and fucose for the lycopadiene race. Although morphologically similar, some important chemical differences exist among algae classified as B. braunii.
PHYSIOLOGICAL VARIABILITY WITHIN TEN STRAINS OF CHAETOCEROS MUELLERI (BACILLARIOPHYCEAE)1
Authors: Johansen Jeffrey R. , Barclay William R. , Nagle Nicholas
Published: October 2004

The effects of temperature, ionic composition, and conductivity on growth rates of ten strains of Chaetoceros muelleri Lemmerman (mostly var. subsalsum Johan. & Rushf.) were studied. Lipid content of stressed and unstressed cells and fatty acid composition were also determined. Considerable physiological variability was observed in the ten strains, although principal components analysis of physiological data indicated that all strains fell into one of two major groups: C. muelleri (var. muelleri and var. subsalsum) and an undescribed Chaetoceros species morphologically close to C. muelleri var. subsalsum. A high degree of agreement was found among morphological, physiological, and biochemical data sets, indicating that physiological and biochemical data may be helpful in making taxonomic decisions in diatoms, particularly in taxa with few morphological characters. We also conclude that nonmorphological characters such as those employed in the present study can be used to test phylogenetic hypotheses formulated from traditional morphological data.
BIOCHEMICAL COMPOSITION AND METABOLIC ACTIVITY OF SCRIPPSIELLA TROCHOIDEA (DINOPHYCEAE) RESTING CYSTS1
Authors: Binder Bruin J. , Anderson Donald M.
Published: October 2004

The composition and metabolic activity of cysts of the marine dinoflagellate Scrippsiella trochoidea (Stein) Loeblich were examined during dormancy, quiescence, and germination. On a per cell basis, newly formed cysts contained an order of magnitude more carbohydrate but significantly less protein and chlorophyll a than did exponentially growing vegetative cells. Loss of lipid and carbohydrate from cysts during the initial dormancy period reflected a respiration rate estimated to be 10% of the respiratory activity in vegetative cells. Among older, quiescent cysts the calculated respiration rate decreased further to approximately 1.5% of the vegetative rate and appeared to proceed largely at the expense of carbohydrate reserves. These estimated rates of respiration were in good agreement with direct measurements of cyst oxygen consumption. The transfer of quiescent cysts to conditions permissive for germination resulted in a rapid increase in respiration rate, as evidenced by carbohydrate loss and O2 consumption. The increased respiratory activity was followed by an increase in protein content and, later, by an increase in chlorophyll a content and photosynthetic capacity. Just prior to germination the P/R ratio became greater than 1, and the estimated chlorophyll‐specific photosynthetic activity reached 75% of the rate in vegetative cells. Complete restoration of photosynthetic and respiratory capacity apparently was not achieved until after excystment. These data confirm the common assumption that dinoflagellate cysts represent true “resting” cells, containing extensive energy reserves and displaying greatly reduced metabolic activity.
CARBON FIXATION IN CULTURED MARINE BENTHIC DIATOMS1
Authors: Zimba Paul V. , Sullivan Michael J. , Glover Hilary E.
Published: October 2004

The enzyme activity of ribulose 1, 5‐bisphosphate carboxylase‐oxygenase (RuBisCO) and phosphoenolpyruvate carboxylase (PEPC) was measured in four species of marine benthic diatoms isolated from subtidal sediments of Graveline Bayou, Mississippi. Enzyme activities were measured in cultures of Amphora micrometra Giffen, A. tenerrima Aleem and Hustedt, Nitzschia fontifuga Cholnoky, and Nitzschia vermicularis Grunow that were grown at light levels supporting μmax and at light‐limiting irradiances. All four species exhibited similar RuBisCO: PEP ratios (range = 1–1.8) at μmax the lowest ratio (0.4) was observed in A. micrometra. Reduced light levels increased PEPC relative to that measured at μmax in two species.

Two‐dimensional paper chromatography was used to determine the first products of carbon fixation in A. micrometra After a 15 s incorporation period, the first product of photosynthetic carbon fixation was 3‐phosphoglycerate even though this alga had a PEPC activity that was three times higher than that of RuBisCO. After 30 s, over 50% of the recovered radioactivity was still in this compound. Stable carbon isotope analyses of a mixture of the four pennate diatoms also suggest the predominant carbon fixation pathway in these benthic diatoms was similar to C3 plants.
TWO CLASS I ALDOLASES IN KLEBSORMIDIUM FLACCIDUM (CHAROPHYCEAE): AN EVOLUTIONARY LINK FROM CHLOROPHYTES TO HIGHER PLANTS1
Authors: Jacobshagen Sigrid , Schnarrenberger Claus
Published: October 2004

Two fructose‐bisphosphate aldolases(EC 4.1.2.13) from Klebsormidium flaccidum Silver, Mattox and Black‐well were purified by affinity elution from phosphocellulose. The two enzymes were subsequently separated by HPLC on an anion‐exchange column (QAE‐silica). The aldolase eluting first represented 5% of the total activity; the other aldolase represented the remaining activity. The activity of the enzymes was not reduced by the presence of 1 mM EDTA or increased by 0.1 mM Zn2+, establishing their character as class I type (Me2+ independent) aldolases. The Km(fructose‐1,6‐bisphosphate) values were 1.7 and 34.7 μM for the enzyme eluting first and second, respectively, from the QAE‐silica column. The subunit molecular masses, as determined by SDS‐PACE, were 40.5 and 37 kD; the specific activities of the purified enzymes were 7.9 and 24.7 · mg−1 protein, respectively. The two aldolases of K. flaccidum are homologous to the cytosol and chloroplast specific isoenzymes of higher plants by several criteria and are therefore probably located in the same cellular compartments in K. flaccidum. The Km and specific activity for the chloroplast aldolase of K. flaccidum are three times higher than for the chloroplast aldolase of higher plants, a remarkable difference. Immunotitration with specific antisera against the chloroplast aldolase of Chlamydomonas reinhardtii Dangeard and spinach showed that the chloroplast aldolase of K. flaccidum was immunochemically intermediate in structure to the respective aldolases of C. reinhardtii and higher plants. K. flaccidum is the second species of Charophyceae (besides Chara foetida Braun) with two class I aldolases as in higher plants whereas two species of Chlorophyceae have only one class I aldolase and, under some conditions, an additional class II (Me2+ dependent) aldolase. Thus, aldolases may turn out, in addition to the known enzymes of glycolate conversion and urea degradation, be a novel enzyme system to evaluate algal evolution along with cytological features.
BEHAVIOR OF CHLOROPLAST NUCLEOIDS DURING THE CELL CYCLE OFCHLAMYDOMONAS REINHARDTII(CHLOROPHYTA) IN SYNCHRONIZED CULTURE1
Authors: Ehara Tomoko , Ogasawara Yutaka , Osafune Tetsuaki , Hase Eiji
Published: October 2004

Cells ofChlamydomonas reinhardtiiDangeard were synchronized under a 12:12 h light: dark regimen. They increased in size during the light period, while nuclear division, chloroplast division and cytokinesis occurred during the dark period. Zoospores were liberated toward the end of the dark period. Changes in profile and distribution of chloroplast nucleoids were followed with a fluorescence Microscope after fixation with 0.1%(w/v) glutaraldehyde followed by staining with 4′.6‐diamidino‐2‐phenylidole (DAPI), a DNA fluorochrome. About ten granular nucleoids were dispersed in the chloroplast at the beginning of the light period (0 h). Within 4 h the nucleoids aggregated around the pyrenoid giving a compact profile. The formation of the compact aggregate of cp‐nucleoids around the pyrenoid occurred with maximal frequency twice during the light period. Toward the end of the light period the nucleoids were transformed into the form of threads interconnected with fine fibrils spreading throughout the chloroplast. Initially the thread‐like nucleoids fluoresced only faintly. The fluorescence of some parts of the threadlike form became brighter over a period of 6 h; these nucleoids were divided into daughter chloroplasts during chloroplast division. Soon after chloroplast division, these thread‐like nucleoids were transformed into about 20 granular forms, which were gradually combined to form about ten larger granular bodies in zoospores immediately prior to liberation from mother cells. Fixation of cells with glutaraldehyde at high concentrations or treatment of cells with protease significantly modified the profiles of DAPI‐stained nucleoids. The different morphologies of chloroplast nucleoids are discussed in relation to changes in configuration of their protein components.
ABSOLUTE CONFIGURATION ANALYSIS OF THE FLAGELLAR APPARATUS OF PTEROSPERMA CRISTATUM (PRASINOPHYCEAE) AND CONSIDERATION OF ITS PHYLOGENETIC POSITION1
Authors: Inouye Isao , Hori Terumitsu , Chihara Mitsuo
Published: October 2004

Pterosperma cristatum Schiller, a member of the Pra‐sinophyceae, was examined with light and electron microscopy with special attention on the absolute configuration of flagellar apparatus components and associated structures. This alga is characterized by asymmetrically arranged basal bodies, connecting fibers and microtubular roots. The microtubular root system is homologous with the cruciate root system, the so‐called X‐2‐X‐2 root system typical of non‐charophycean green algae. Two ducts are associated with microtubular roots. A similar flagellar apparatus and duct system was found in two other prasinophyte genera, Pyramimonas and Halosphaera. The close phylogenetic affinity of these three genera is discussed.
THE FINE STRUCTURE OF TWO PHOTOSYNTHETIC SPECIES OF DINOPHYSIS (DINOPHYSIALES, DINOPHYCEAE)1
Authors: Lucas Ian A. N. , Vesk Maret
Published: October 2004

Two closely related, photosynthetic species belonging to the genus Dinophysis were examined, D. acuminata Claparède et Lachmann and D. fortii Pavillard. Typical dinoflagellate features include the amphiesmal covering enclosing the cells and the structure of the nucleus and mitochondria. Many other characteristics seem to be specific to the order Dinophysiales. Many rhabdosomes are present, and complex mucocysts are found beneath the amphiesma. The thecal pores are unusual with the base of the pore occluded by a thin disc that is continuous with the main amphiesmal plate. The structure of the apical pore is also distinctive. Chloroplasts are grouped together in chromatospheres, enclosed by a double membrane, and contain paired thylakoids with electron dense contents in the lumen. The two pusules are extensive, each branching off the flagellar canal, and consisting of a large antechamber and a number of convoluted sacs. The entrance of each antechamber, and site of an emerging flagellum, is surrounded by a striated fibrous collar. Near the flagellar pore is a prominent microtubular/microbody complex which penetrates deep into the cell cytoplasm. Consideration is given to taxonomic position of the Dinophysiales and also to the nature and origins of the chloroplasts.
PHENOTYPIC PLASTICITY IN SCENEDESMUS COMMUNIS (CHLOROPHYCEAE). I. RELATIONSHIP OF S. COMMUNIS TO S. KOMAREKII1
Authors: Egan Patrick F. , Trainor Francis R.
Published: October 2004

When scenedesmus communis Hegew. (UTEX 76) was transferred daily in dilute media and a low cell density was maintained (ca. 1000 cells · mL−1), up to 30% unicells were produced in that population. Unlike previously described uncell‐coenobium‐unicell transformation with other species, these unicells never produced S. communis coenobia (large coenobium type, LCT) but rather small coenobium type (SCT) resembling S. komarekii Hegew. Growth and morphological development of the paratype strain of S. komarekii (UTEX 1236) was compared with an isolated SCT strain (SCT 76–8). SCT 76–8 never produced LCTs and grew significantly faster than UTEX 1236. Both SCT 76–8 and UTEX 1236 produced uncells at low cell densities. Coenobia formed when cell densities increased over time in batch cultures. SCT 76–8 and UTEX 1236 did not differ morphologically when viewed with the light microscope. Under scanning electron microscopy, an outer opaque layer covered an inner warty layer on unicells. The outer layer was reduced or absent in coenobia from batch cultures in stationary growth. In addition, long spikelets, not present on the walls of unicells, were prominent on coenobial walls. The spikelets of UTEX 1236 appeared smaller and more uniformly distributed than in strain 76–8. In contrast, the surface wall morphology of LCT S. communis was composed of an outer reticulate layer supported by spikelets and appeared as a pentagonal meshwork covering the cell walls. This phenotypic plasticity, as demonstrated by SEM and light microscopy, provides further evidence needed for an understanding of Scenedesmus evolution.
PHOTOADAPTATION, GROWTH AND PRODUCTION OF BOTTOM ICE ALGAE IN THE ANTARCTIC1
Authors: Cota Glenn F. , Sullivan Cornelius W.
Published: October 2004

Biomass, chemical composition, growth rates and the photosynthetic response of natural populations of sea ice algae in McMurdo Sound, Antarctica were followed over most of the spring bloom to examine temporal variability under a relatively constant incident irradiance (ca. 1500–1700 μE · m‐2· s‐1 at solar noon). Collection were restricted to bottom 20 cm of the ice sheet in an area with little or no snow (0–5 cm). At low temperature and irradiance these algae normally exhibited low assimilation numbers (ca. 0.1–0.4 mg C · mg Chl‐1· h‐1). Average growth rates (0.02–0.45 d‐1), based on changes in standing stocks, were also low. Biomass, biochemical composition, growth rates, assimilation numbers and photosynthetic efficiencies (mg C · mg Chl‐1· h‐1 (μE · m‐2· s‐1)‐1) displayed large fluctuations over periods of several days during the growth season. On the other hand, Ik which is an index of photoadaptation, and Im, the optimal irradiance for photosynthesis, were relatively constant with less than twofold variation throughout our study.

Substantial nutrient fluxes (3.3–8.0 mmol Si or N · m‐2· d‐1) were necessary to satisfy the minimum nutrient demand for the observed biomass levels and population growth rates; over the 41 days of our study, integrated nutrient demand represented 69–150 mmol N or Si · m‐2, Only 5–25% of this total demand could be met by all of the nutrients in the ice sheet, if they were readily available. However, adequate amounts were present in the top few meters of the water column. With small nutrient gradients in surface waters below the sea ice, vertical eddy diffusivities on the order of 3.8–9.3 cm2· s‐ should supply sufficient nutrients to meet algal demand.
LIPID SYNTHESIS AND FATTY ACID COMPOSITION IN NANNOCHLOROPSIS SP. (EUSTIGMATOPHYCEAE) GROWN IN A LIGHT‐DARK CYCLE1
Authors: Sukenik Assaf , Carmeli Yael
Published: October 2004

Chemical composition and lipid biosynthesis were studied in the marine eustigmatophyte Nannochloropsis sp. Grown under a 12:12 h light‐dark regime. Cellular division occurred in the dark and was associated with a reduction in cell volume. The cellular content of chlorophyll a and carotenoids increased during the light period and decreased during the dark period. Other cellular components, such as proteins, carbohydrates and lipids, followed a similar pattern. Nannochloropsis sp. Incorporated acetate, mostly into lipids during the light period, whereas a low rate of acetate incorporation was observed during the dark period, mostly into nonlipid compounds. Neutral lipids such as triacylglycerol were synthesized and accumulated in the light and showed a rapid turnover in the dark. Polar structural lipids such as monogalactosyl diacylglycerol were synthesized during the light period and hardly turned over during the dark period. Changes in lipid content were associated with variations in cellular fatty acid composition. The light period was characterized by an increase in the percentage of C16:0 and 16:1 fatty acids associated with triacylglycerols. However, in the dark period, as triglycerides were consumed for cellular maintenance, the relative distribution of the C20:5 fatty acid associated with the galactolipids increased.
ROLE OF LIGHT AND THE CELL CYCLE ON THE INDUCTION OF SPERMATOGENESIS IN A CENTRIC DIATOM1
Authors: Armbrust E. Virginia , Chisholm Sallie W. , Olson Robert J.
Published: October 2004

The centric diatom, Thalassiosira weissflogii Grun., can be induced to undergo spermatogenesis by exposing cells maintained at saturating levels of continuous light to either dim light or darkness. Using flow cytometry to determine the relative DNA and chlorophyll content per cell, the number of cells within a population that responded to and induction signal was measured. From 0 to over 90% of a population differentiated into male gametes depending upon both the induction trigger and the population examined, regardless of the average cell size of the population. Through the use of synchromized cultures, we demonstrated that responsiveness to an induction trigger was a function of cell cycle stage; cells in early G1 were not yet committed to complete mitosis and were induced to form male gametes, whereas cells further along in their cell cycle were unresponsive to these same cues. A simple model combining the influence of light on the mitotic cell cycle and on the induction of spermatogenesis is proposed to explain the observed diversity in population responses to changes in light conditions.
THE FOSSIL GREEN ALGA MIZZIA (DASYCLADACEAE): A TOOL FOR INTERPRETATION OF PALEOENVIRONMENT IN THE UPPER PERMIAN CAPITAN REEF COMPLEX SOUTHEASTERN NEW MEXICO1
Authors: Kirkland Brenda L. , Chapman Russel L.
Published: October 2004

A paleoenvironmental study of the dasyclad Mizzia Schubert, 1907 is potentially important because, unlike most of the other fossil reef‐dwelling organisms found in the Guadalupe Mountains, the fossil Mizzia (restricted to the Permian) has a modern analog, Cymopolia Lamouroux, 1916 (Cretaceous to Holocene). The overall morphology of the two genera is similar: both are articulated, and observations on our specimens suggest that both were branched. The transition from the remarkably high‐diversity sponge and algal assemblage in the reef into the remarkably low‐diversity dasyclad‐dominated assemblage in the back reef is abrupt, occurring over distances as short as 10 m. Mizzia is the dominant and usually the only component in grainstones, packstones, and wackestones found; immediately shelfward of the Capitan reef. The low percentage of broken segments (average 10%) and the discovery of several intact sections of thallus are evidence against wave action as a possible limiting factor. Because the climate in the Guadalupe Mountains was extremely arid and because dasyclads are euryhaline, hypersalinity is considered the most likely limiting factor in this case. Our conclusion that prolific stands of dasyclads formed in shallow protected lagoons immediately behind an emergent barrier reef is not compatible with the currently accepted marginal mound hypothesis for deposition of the Capitan reef complex. We suggest that the marginal mound model must either be modified or abandoned in favor of the originally proposed barrier reef model of deposition.
DNA POLYMORPHISM WITHIN THE WH7803 SEROGROUP OF MARINE SYNECHOCOCCUS SPP. (CYANOBACTERIA)1,2
Authors: Wood A. Michelle , Townsend David
Published: October 2004

Genetic differences among ten strains of chroococcoid cyanobacteria (Synechococcus spp.) were identified by Southern blot hybridization. Data on shared number of restriction fragment length polymorphisms were used to identify the pattern and degree of genetic relatedness among the strains by two different methods of phylogenetic analysis. All the marine strains in the study contained phycoerythrin (PE) and cross‐reacted with antisera directed against strain WH7803. Five contained a PE composed of phycourobilin (PUB) and phycoerythrobilin (PEB) Chromophores, and three contained a PE composed of only PEB chromophores. Two freshwater strains which do not contain PE and do not cross‐react with the anti‐WH7803 serum were included in the study for comparison. Dollo Parsimony analysis and cluster analysis showed that the WH7803 serogroup includes at least four widely separated genetic lineages. Strains within each lineages were closely related but the differences between lineages were as great as those between any of the marine lineages and the freshwater lineage. Strains cultured simultaneously from the same water mass were associated with different lineages. Thus, we conclude that natural assemblages of marine. Synechococcus are, at least occasionally, composed of individuals as genetically distinct from each other as members of different species or genera in other taxa.
SEASONAL SUCCESSION OF ALGAL PERIPHYTON FROM A WASTEWATER TREATMENT FACILITY1
Authors: Davis Laurie S. , Hoffmann James P. , Cook Philip W.
Published: October 2004

Attached algal populations were sampled at weekly or biweekly to characterize successional changes in the secondary clarifiers of a wastewater treatment plant. Three communities were compared from areas of slow, medium and rapid current velocities. In general, the algae resembled those reported for other hypereutrophic flowing water. Of the twenty‐three algae recorded, Stigeoclonium, Oedogonium, Oscillatoria, Lyngbya, and Pleurocapsa were dominant at some point in the 15 month sampling period. Nutrient concentrations were consistently high (N = 1.1–21.4 mg·L−1; P = 0.1–10.4 mg·L−1); therefore, changes in temporal distribution of algae were probably dependent on seasonal changes in light and temperature. Colonization of artificial substrates was also observed. Small unicellular algae were the first autotrophs to attach and these were followed by larger filamentous forms.
EFFECTS OF ARSENATE ON GROWTH OF NITROGEN‐AND PHOSPHORUS‐LIMITED CHLORELLA VULGARIS (CHLOROPHYCEAE) ISOLATES1
Authors: Creed Irena F. , Havas Magda , Trick Charles G.
Published: October 2004

The effects of arsenate on the growth characteristics of five isolates of the freshwater alga, Chlorella vulgaris Beij., were examined. Two field isolates originated from arsenic‐contaminated sites in Yukon, Canada and Kyushi, Japan; two reference isolates were obtained from the University of Texas Culture Collection. One isolate was selected for arsenic‐tolerance in the laboratory. All five strains survived in culture solutions containing high arsenate concentrations. Arsenate (1–25 mM As) reduced photosynthesis and cell growth, as reflected by induced lag periods, slower growth rates, and lower stationary cell yields. Field isolates had shorter lag periods, higher growth rates, and enhanced cell yields compared to lab isolates when exposed to the same arsenic concentrations. Growth of the phosphorus‐limited field strains was stimulated by the addition of arsenic. The cell yield of phosphorus‐limited C. vulgaris Yukon, when treated with arsenic, was two times that of the phosphorus‐limited control. This pattern was not evident when photosynthesis was used as a measure of cell response.