bluuebunny/crossref_metadata_2025_split huggingface dataset:
RETENTION OF P‐NITROPHENOL AND 4‐METHYLUMBELLIFERONE BY MARINE MACROALGAE AND IMPLICATIONS FOR MEASUREMENT OF ALKALINE PHOSPHATASE ACTIVITY1
Authors: Hernández Ignacio , Whitton Brian A. 
Published: October 2004

ABSTRACTDuring standardization of the methodology for estimating “cell‐bound” alkaline phosphatase activity (APA: phosphomonoesterase) inFucus spiralisL. (Phaeophyta), some of the nonphosphate moiety of the original phosphomonoester was found to be released to the medium subsequent to completion of the routine assays. This occurred with the two substrates generally employed in APA measurements: p‐nitrophenyl phosphate (pNPP) and 4‐methylumbelliferyl phosphate (MUP). Other marine macrophytes tested showed the same phenomenon. The conditions influencing retention were investigated to establish the simplest procedure for measuring APA. When using pNPP, the release of the product (p‐nitrophenol) after the assays was maximum when assays were run for longer than 20 min and at slightly acid pH or at high pNPP concentrations. When using MUP, the leakage of the product (4‐methylumbelliferone) after the assays was maximum when APA measurements were run for longer than 40 min and at neutral pH or at high MUP concentrations. The significance of the leakage of the nonphosphate moiety after APA assays is discussed.
IDENTITY OF THE ENDOSYMBIONT OF PERIDINIUM FOLIACEUM (PYRROPHYTA): ANALYSIS OF THE rbcLS OPERON1
Authors: Chesnick Joby Marie , Morden Clifford W. , Schmieg Andrea M. 
Published: October 2004

ABSTRACTExtant chromophytic algae have been suggested to have originated via the engulfment of a photo synthetic alga by a colorless protist. The dinoflagellate Peridinium foliaceum (Stein) Biecheler contains a reduced chlorophyll c–containing endosymbiont and, thus, represents an evolutionary intermediate stage in the establishment of chloroplasts. Although the exact phylogenetic relationship of the symbiont to extant algal species is unknown, it had been suggested that the P. foliaceum symbiont was either a diatom or a chrysophyte. Identification of the closest living relative of the P. foliaceum symbiont would provide a free‐living model system with which the photosynthetic symbiont could be compared. Nucleotide sequence analysis of rbcL and rbcS (encoding the large and small subunits ofribulose‐1,5‐bisphosphate carboxylase/oxygenase) by the P. foliaceum symbiont was performed to provide insights into its identity. Cloned restriction fragments from a chloroplast DNA library were screened, and clones encoding the rbcLS operon were sequenced. Parsimony phylogenetic analysis was performed for each gene. Our data strongly suggest that the symbiont originated from a photosynthetic diatom.
AMPHIDINIUM OPERCULATUM VAR. NOV. GIBBOSUM (DINOPHYCEAE), A FREE‐SWIMMING MARINE SPECIES PRODUCING CYTOTOXIC METABOLITES1
Authors: Maranda Lucie , Shimizu Yuzuru 
Published: October 2004

ABSTRACTA single‐cell isolate of Amphidinium from the northern Caribbean Sea was identified as A. operculatum Clap. et Lack. var. nov. gibbosum Maranda et Shimizu based on a morphological and ultrastructural study. This free‐swimming dinoflagellate, which was found to produce potent antitumor metabolites, is elongate and asymmetrical. It is compared with two close relatives A. klebsii Kofoid et Swezy and A. carterae Hulburt. Amphidinium operculatum var. gibbosum can be distinguished from A. klebsii on the basis of shape while it differs from A. carterae on the basis of size, shape, cell surface, and chloroplast arrangement. The shape and size of the nucleus and the presence of mucocysts also differentiate the gibbosum variety from its two relatives. The architecture of the pusule may ultimately provide the best ultrastructural discriminating character. Otherwise, the general ultra‐structure of the Caribbean isolate is typical of many unarmored photo synthetic dinoflagellates with amphiesma, condensed chromosomes, trichocysts, mitochondria with tubular cristae, and trilamellar chloroplasts.
EFFECT OF HIGH IRRADIANCE ON RECRUITMENT OF THE GIANT KELP MACROCYSTIS (PHAEOPHYTA) IN SHALLOW WATER1
Authors: Graham Michael H. 
Published: October 2004

ABSTRACTLaboratory and field experiments were done hi Still‐water Cove, Carmel Bay, California, and Monterey Harbor, California, to determine the effect of photosynthetically active radiation (PAR) on the shallow (upper) limit of giant kelp, Macrocystis pyrifera (L.) C. Agardh. At shallow depths, M. pyrifera did not recruit or grow to macroscopic size from gametophytes or embryonic sporophytes transplanted to vertical buoy lines; sharp decreases in PAR with depth coincided with observed recruitment and sporophyte distributions. Shade manipulations indicated that settlement of M. pyrifera zoospores was decreased, but not prohibited, by high PAR. Postsettlement stages (gametophytes and embryonic sporophytes), however, survived only under shade. These results suggest that high PAR can inhibit the recruitment of M. pyrifera to shallow water by killing its postsettlement stages; whether or not ultraviolet (UV) radiation also inhibits recruitment was not tested. In either case, however, it appears that high irradiance (PAR and/or UV) regulates the shallow limit of M. pyrifera prior to temperature and desiccation stresses inherent to intertidal regions. In an additional experiment, recruitment or growth of transplanted gametophytes or embryonic sporophytes of Macrocystis integrifolia Bory also did not occur at shallow depths, suggesting that this shallow water species accesses high irradiance regions via a method other than sexual reproduction.
CHARACTERIZATION OF NITROGEN UPTAKE BY NATURAL POPULATIONS OF AUREOCOCCUS ANOPHAGEFFERENS (CHRYSOPHYCEAE) AS A FUNCTION OF INCUBATION DURATION, SUBSTRATE CONCENTRATION, LIGHT, AND TEMPERATURE1
Authors: Lomas Michael W. , Gilbert Patricia M. , Berg Gry M. , Burford Michele 
Published: October 2004

ABSTRACTNitrogen uptake studies were conducted during an aestival “brown tide” bloom in Shinnecock Bay, Long Island, New York. The same station was sampled in late July and mid‐August 1995 when Aureococcus anophagefferens composed >90% and 30–40% of the total cell density, respectively. Experiments were designed to examine the effect of incubation duration on the uptake kinetics, and the effect of light and temperature dependencies of NH4+, urea, and NO3− uptake. Maximum specific uptake rates (V'max) decreased in the order NH4+, urea, NO3− and were nonlinear with time for NH4+ and urea, both of which exhibited an exponential decline between 1 and 10 min and then did nut significantly change for 60 min. Nitrogen uptake kinetic experiments exhibited a typical hyperbolic response for urea and NO3−. Half‐saturation constants. (Ks) were calculated to he 0.03 and 0.12 μmol · L−1 for urea and NO3−; respectively, but could not be calculated for NH4+ under these experimental conditions. Nutrient uptake rate versus, irradiance (NI) experiments showed that maximum uptake rates occurred at ≤% of incident irradiance on both sampling dates and that values of V′max‐cell (NH4+) were on average 30% greater than V′max‐cell (urea). A7°–9°C temperature decrease in incubation temperature between the two NI experiments in August resulted in a 30% decrease in V′max‐cell(NH4+), no change in V′max‐cell(urea), and a 3–4‐fold decrease in calculated Klt values for both NH4+ and urea. The results from these experiments demonstrate that A. anophagefferens has a higher affinity for NH4+ and urea than for NO3− and that this particular species is adapted to use these substrates at low irradiances and concentrations. The data presented in this study are also consistent with the hypothesis that A. anophagefferens may be an oceanic clone that was displaced by an anomalous oceanographic event.
ISOLATION AND CHARACTERIZATION OF A VIRUS INFECTING PHAEOCYSTIS POUCHETII (PRYMNESIOPHYCEAE)1
Authors: Jacobsen Anita , Bratbak Gunnar , Heldal Mikal 
Published: October 2004

ABSTRACTA virus infecting the haptophyte Phaeocystis pouchetii (Hariot) Lagerheim was isolated from Norwegian coastal waters in May 1995 at the end of a bloom of this phytoplankter. The virus was specific for P. pouchetii because it did not lyse 10 strains of P. globosa Scherffel, Phaeocystis sp., and P. antarctica Karsten. It was a double‐stranded DNA virus, and the viral particle was a polyhedron with a diameter of 130–160 nm. The virus had a main polypeptide of about 59 kDa and at least five minor polypeptides between 30 and 50 kDa. The latent period of the virus when propagated in cultures of P. pouchetii was 12–18 h, and the time required for complete lysis of the cultures was about 48 h. The burst size was estimated to be 350–600 viral particles per lysed cell.
ECOLOGICAL CONSIDERATIONS OF DIATOM CELL MOTILITY. I. CHARACTERIZATION OF MOTILITY AND ADHESION IN FOUR DIATOM SPECIES1
Authors: Cohn Stanley A. , Weitzell Roy E. 
Published: October 2004

ABSTRACTTo better determine the ecological role of motility in pennate diatoms, we quantitatively characterized several motility and adhesion properties of four species of motile pennate diatoms(Craticulasp.,Pinnulariasp.,Nitzschiasp., andStauroneissp.)isolated from the same freshwater pond. Using computer‐assisted video microscopy, we measured speed, size/shape, functional adhesion, path curvature, and light sensitivity for these species, each of which shows a distinctive set of motile behaviors. The average speeds ofStauroneis, Pinnularia, Nitzschia, andCraticulacells are 4.6, 5.3, 10.4, and 10.0 μm · s−1, respectively.CraticulaandNitzschiacells move in a relatively straight path (<4 degrees rotation per 100 μm movement),Stauroneisexhibits minor rotation (about 7 degrees per 100 μm movement), andPinnulariarotates considerably during movement (about 22 degrees per 100 μm moved). Functional adhesion (as measured by the release rate of attached cells from the underside of an inverted coverslip) shows a half time for cell release of approximately 50 min forCraticula, 192 min forPinnularia, and >1 day forNitzschiaandStauroneis.Direction reversal at light/dark boundaries, which appears to be the main contributor to diatom Phototaxis, is most responsive forCraticula, Pinnularia, andNitzschiaat wavelengths around 500 nm.CraticulaandNitzschiacells are the most sensitive in the photophobic response, with over 60% of these cells responding to a 30‐1x light/dark boundary at 500 nm, whereasPinnulariacells are only moderately responsive at this irradiance, showing a maximal response of approximately 30% of cells at 450 nm.Stauroneiscells, in contrast, had a maximal photosensitive response at 700 nm, suggesting that this cell type may use a different response mechanism than the other three cell types. In addition,CraticulaandPinnulariashow a net movement out of the light spot when illuminated at 650 nm, whereasStauroneisshows a net movement out of the light spot when illuminated at 450 nm. Such quantitative characterizations of species‐specific responses to environmental stimuli should give us a firm foundation for future studies analyzing the behavior of interspecies diatom competition for limited light or nutrient resources.
COMPETITION FOR PHOSPHORUS AMONG PLANKTONIC DESMID SPECIES IN CONTINUOUS‐FLOW CULTURE1
Authors: Spijkerman Elly , Coesel Peter F. M. 
Published: October 2004

ABSTRACTWhen grown under stringent P limitation, affinity for P uptake and growth inStaurastrum pingueTeil. andStaurastrum chaetoceras(Schr.) G. M. Smith (both originating from eutrophic lakes) were of the same magnitude, whereas these parameters forCosmariumabbreviatum Rac. var.planctonicumW. & G. S. West (isolated from a meso‐oligotrophic lake) were significantly higher in value. On the other hand, at all growth rates tested, maximum P uptake rates were lower inC. abbreviatumthan in the twoStaurastrumspecies. The outcome of competition between eitherStaurastrumspecies andC. abbreviatumin mixed chemostats under different levels of continuous P limitation was in agreement with what could be predicted from the species‐specific affinity parameters:Staurastrumwas outcompeted at dilution rates lower than 0.012 h−1, calculated to correspond with external inorganic P concentrations lower than 0.02 μM P, but won out at higher dilution rates. When P was added in two pulses of 2.5 μmol · L−1a week instead of continuously,S. chaetocerasoutcompetedC. abbreviatumat a slow rate. When P was supplied as a daily pulse of 0.7 μmol · L−1, a stable coexistence ofS. chaetocerasandC. abbreviatumwas established,Staurastrumpredominating the culture in cell numbers at ca. 85%. The results show that P uptake and growth characteristics of the three species can predict the outcome of competition under various P‐limited conditions. Specific growth kinetic parameters as found in this study may also explain distribution patterns of the species observed in the field.
INCORPORATION OF FRESHWATER RHODOPHYTA INTO THE CASES OF CHIRONOMID LARVAE (CHIRONOMIDAE, DIPTERA) FROM NORTH AMERICA1
Authors: Sheath Robert G. , Müller Kirsten M. , Colbo Murray H. , Cole Kathleen M. 
Published: October 2004

ABSTRACTChironomid larvae incorporate pieces of freshwater red algae into their cases from a wide geographic range in North America, extending from southern Canada to central Mexico. The Rhodophyta used in this process represent two orders (Acrochaetiales and Batrachospermales), five genera(Audouinella, Batrachospermum, Lemanea, Paralemanea, andSirodotia), and 14 species from 21 locations. Three genera from the chironomid subfamily Orthocladiinae make these cases: Cardiocladius, Eukiefferiella, andOrthocladius.TheEukiefferiella claripennisgroup was the most frequently observed infrageneric taxon using red algae in its cases. The cases were tubular in shape with longitudinally oriented strips of algae held together by silken threads. Some of the cases constructed withBatrachospermumandSirodotiaalso had several lateral branches of the alga radiating from the tube.
NONEQUILIBRIUM RATES OF PHOTOSYNTHESIS AND RESPIRATION UNDER DYNAMIC LIGHT SUPPLY1
Authors: Kübler Janet E. , Raven John A. 
Published: October 2004

ABSTRACTTo identify processes that might account for differences in growth rates of rhodophytes under constant and dynamic light supply, we examined nonequilibrium gas exchange by measuring time courses of photoinduction, loss of photoinduction, and respiration rates immediately after the light–dark transition. Using the rhodophyte species Palmaria palmata (Huds.) Lamour and Lomentaria articulata (Huds.) Lyngb., we compared the effects of growth‐saturating constant photon flux density (PFD) (95 μmol photons · m−2· s−1) to those of a dynamic light supply modeled on canopy movements in the intertidal zone (25 μmol photons · m−2· s−1 background PFD plus light flecks of 350 μmol photons · m−2· s−1, 0.1 Hz). The time required for P. palmata and L. articulata to be fully photoinduced was not affected by the dynamics of light supply. L. articulata required only 6 min of illumination with either fluctuating or constant light to be completely induced compared to 20 min for P. palmata. The latter species also lost photoinduction more rapidly than did L. articulata in the dark. There was no significant decline in photoinduction state for either species at the background PFD. The time courses of respiration after illumination with constant and fluctuating light were significantly different for P. palmata but not for L. articulata when the total photon dose was equal. In general, gas exchange of P. palmata appeared to be particularly sensitive to the temporal distribution of light supply whereas that of L. articulata was sensitive to the amplitude of variations, being photoinhibited at high PFD. These results are discussed in terms of the different mechanisms of inorganic carbon acquisition in the two species.
MODULATION OF FATTY ACIDS IN THE MEMBRANES OF ANACYSTIS NIDULANS (CYANOBACTERIA): INCORPORATION OF ODD‐NUMBERED CARBON FATTY ACIDS1
Authors: Khan Mobashsher U. , MacKenzie Samuel L. , Williams John P. 
Published: October 2004

ABSTRACT Anacystis nidulans Richt., a unicellular cyanobacterium, can incorporate exogenously supplied fatty acids, including odd‐numbered carbon fatty acid (OFAs), into the acylglycerols of cell membranes. Data are presented for the uptake of undecanoic acid (11:0) into cells of A. nidulans, the subsequent elongation up to C17, and incorporation of OFA into the four major membrane acylglycerols. The incorporation of OFAs was followed by desaturation of part of the saturated fatty acid to monoenoic fatty acid. Positional analyses of the double bonds of these manoenoic fatty acids suggest that there is one desaturase that inserts a Δ9 bond in both odd‐ and even‐numbered fatty acids of varying chain length. Our data also suggest that there is no positional specificity for chain length on the glycerol backbone by the acyltransferases.
PHOTOINHIBITION OF MECHANICALLY STIMULABLE BIOLUMINESCENCE IN THE HETEROTROPHIC DINOFLAGELLATE PROTOPERIDINIUM DEPRESSUM (PYRROPHYTA)1
Authors: Li Yaqin , Swift Elijah , Buskey Edward J. 
Published: October 2004

ABSTRACTPhotoinhibition of mechanically stimulable bioluminescence (MSL) in the heterotrophic dinoflagellate Protoperidinium depressum Bailey was investigated using samples collected from the Massachusetts and southern Texas coasts. The times for both photoinhibition of MSL (ca. 10 min) and dark recovery from photoinhibition of MSL (ca. 45 min) in this species were similar to those reported for autotrophic dinoflagellates. The degree of photoinhibition of MSL was a linear function of the logarithm of photon flux density (PFD). The threshold PFDs for the photoinhibition of MSL were 0.02, 0.6, and 21 μmol photons · m−2· s−1 for broad‐band blue, green, and red light, respectively. These PFDs are lower than those required for photoinhibition of MSL by the autotrophic dinoflagellates Pyrocystis lunula and Ceratium fusus. We speculate that photosynthetic pigments in autotrophic dinoflagellates shield the photoreceptor that causes photoinhibition of MSL, thus lowering the sensitivity of these dinoflagellates to light. When field‐collected P. depressum were kept in the laboratory without growth for a week, photoinhibition of MSL's sensitivity to light increased progressively along with 1) a decrease in its bioluminescence capacity (BCAP), 2) a decrease in the ratio of MSL to BCAP (MSL/BCAP), and 3) a decrease in the orange pigmentation (probably carotenoid) of the dinoflagellate. The action spectrum for photoinhibition of MSL in P. depressum was characterized primarily with a broad peak in the blue extending into the green. We suggest that carotenoid was not a photoreceptor for the photoinhibition of MSL in P. depressum because the peak of the action spectrum was too broad and extended too far into the green part of the spectrum, and because the orange pigment present decreased as photoinhibition of MSL became more sensitive to light.
A SALT‐INDUCED CHLOROPLAST PROTEIN IN DUNALIELLA SALINA (CHLOROPHYTA)1
Authors: Shan Lu , Xiao‐Ning Zhang , Peng‐Yun Li , Zhi‐Li Liu , Zhong‐Hao Xia 
Published: October 2004

ABSTRACTThe unicellular green alga Dunaliella salina Teod, is halophilic and wall‐less. The cell acclimates to osmotic stresses by accumulation or degradation of glycerol. To investigate other mechanisms involved in its physiological recovery following hyperosmotic shocks, protein profiles from cells grown in various salinities were compared. A 13‐kDa protein (P13) accumulated when cells were subjected to drastic hyperosmotic shock. Front our results with antibiotic‐treated cells and purified chloroplasts, we believe that this component results from de novo translation in chloroplasts. The solubility of P13 was strongly promoted by Triton X‐100. Its accumulation was correlated with the recovery of photosynthesis.
CHANGES IN THE ULTRASTRUCTURE OF SYMBIOTIC ZOOXANTHELLAE (SYMBIODINIUM SP., DINOPHYCEAE) IN FED AND STARVED SEA ANEMONES MAINTAINED UNDER HIGH AND LOW LIGHT1
Authors: Muller‐Parker Gisèle , Lee Kit W. , Cook Clayton B. 
Published: October 2004

ABSTRACTThe ultrastructure of symbiotic dinoflagellates (Symbiodinium sp., zooxanthellae) in the sea anemone Aiptasia pallida Verrill was examined in well‐fed or starved (up to 120 days) anemones maintained under two light levels (5 and 50 μmol · m−2· s−1). Cell size of zooxanthellae was not affected by feeding history; however, both light and feeding history affected the relative cell volume of chloroplasts, lipids, and vacuoles. Stereological analysis of transmission electron micrographs showed that algae in low‐light starved anemones had 10 times as much lipid (17.4% of cell volume) as those in well‐fed anemones under the same light conditions (1.8%). The lipid content of algae from anemones in high light increased from 15.4% in well‐fed anemones to 30.1% in starved anemones. The starch content of zooxanthellae in low‐light anemones was law (4.1%) and not affected by feeding history, while the starch content of zooxanthellae in high‐light anemones was greater (10.7%), with some differences among groups. Algal photoacclimation to low light included an increase in chloroplast relative volume from 17% (in well‐fed high‐light anemones) to 33% in well‐fed low‐light anemones. Starvation of the host resulted in a significant decrease in chloroplast volume in zooxanthellae in anemones at both light levels. Morphometry provides quantitative confirmation of biochemical and physiological data on zooxanthellae, because the changes in zooxanthellae with starvation of the host are consistent with other indicators of nutrient limitation of zooxanthellae of A. pallida held without food for long periods of time.
A GAMETOPHYTE CELL WALL PROTEIN OF THE RED ALGA PORPHYRA PURPUREA (RHODOPHYTA) CONTAINS FOUR APPARENT POLYSACCHARIDE‐BINDING DOMAINS1
Authors: Liu Qing Yan , Ross Neil , Lanthier Pat , Reith Michael 
Published: October 2004

ABSTRACTA complementary DNA(cDNA)clone from a Porphyra purpurea (Roth) C. Agardh gametophyte‐specific subtracted cDNA library was found to encode a protein containing a signal peptide and four very similar regions with a high degree of amino acid sequence similarity to the cellulose‐binding domains of fungal celluloses. Northern hybridization analysis indicated that the messenger RNA of this cDNA is highly abundant in the gametophyte but not detectable in the sporophyte. In vitro translation of the cDNA in the presence of canine pancreatic microsomes demonstrated that the signal peptide is capable of directing the protein into the endoplasmic reticulum where it is glycosylated. Because these observations suggested a possible role as a gametophyte‐specific cell wall protein, cell wall protein, were isolated and a major protein having a molecular weight similar to that estimated for the encoded protein was purified. N‐terminal sequence analysis indicated that this was the protein encoded by the cDNA. The abundance and organization of this protein suggest a role as a cell wall structural protein involved in cross‐linking polysaccharides.