bluuebunny/crossref_metadata_2025 huggingface dataset:
CYANOBACTERIAL EVOLUTION AND PROCHLOROPHYTE DIVERSITY AS SEEN IN DNA‐DEPENDENT RNA POLYMERASE GENE SEQUENCES1
Authors: Palenik Brian , Swift Hewson
Published: October 2004

Nucleotide sequence data from DNA‐dependent RNA polymerase (rpoC) genes were used to examine the phylogenetic relationships among the phycobiliprotein‐ and three known chlorophyll b‐containing (prochlorophyte) cyanobacteria. The phylogenetic trees obtained confirm the polyphyletic nature of the prochlorophytes. Data from Prochloron cells obtained from six different tunicate host species suggest that at least two closely related groups of Prochloron exist in the same area in Palau, West Caroline Islands. Overall, however, the genetic diversity within the analyzed samples was much smaller than within the nonsymbiotic Prochlorococcus.
ECOPHYSIOLOGY OF TROPICAL RHODOPHYTES. I. MICROSCALE ACCLIMATION IN PIGMENTATION1,2
Authors: Beach Kevin S. , Smith Celia M.
Published: October 2004

Microscale pigment adjustments to a tropical photosynthetically active radiation and ultraviolet (UV) environment by the intertidal turf algae Ahnfeltiopsis concinna (J. Ag.) Silva et DeCew and Laurencia mcdermidiae (J. Ag) Abbott were promoted by thalli densities that self‐shade the under story portions of the same diminutive axes. Tissues of A. concinna from canopy microsites had significantly reduced levels of phycoerythrin, phycocyanin, and allophycocyanin compared to tissues from understory microsites of the same axes. Tissues of L. mcdermidiae from canopy microsites had reduced levels of only phycoerythrin compared to tissues from understory microsites. These alterations coupled with enhanced levels of carotenoid and UV‐absorbing compounds in tissues from canopy compared to tissues from understory microsites indicated a pattern of remarkably sensitive photoacclimation over the ≤10‐cm axes of these turf‐forming rhodophytes.

Microscale variation in the in vivo UV absorbance capabilities for turfs of A. concinna and L. mcdermidiae was directly related to the amount of extractable UV‐absorbing compounds. An in vivo absorbance signature at ∼345 nm appears to provide a method to quickly and accurately gauge the potential UV‐shielding capacity of primary producers even at remarkably fine ecological scales. The capacity for highly responsive biochemical adjustments that result in marked canopy–understory distinctions coupled with a turf morphology may be crucial for macroalgal tolerance of physiological stresses associated with tropical intertidal zones. This responsive capacity allows for enhanced photoprotective mechanisms in tissues from canopy microsites while optimizing irradiance capture in deeply shaded tissues from understory microsites < 10 cm away.
ECOPHYSIOLOGY OF TROPICAL RHODOPHYTES. II. MICROSCALE ACCLIMATION IN PHOTOSYNTHESIS1
Authors: Beach Kevin S. , Smith Celia M.
Published: October 2004

Parameters of photosynthesis vs. irradiance curves varied markedly between tissues from microsites along the < 10‐cm axes of the tropical intertidal red algae Ahnfeltiopsis concinna (J. Ag.) Silva et DeCew and Laurencia mcdermidiae (J. Ag.) Abbott. Differences in photosynthetic performance between tissues from canopy and understory microsites indicates that L. mcdermidiae exhibited an expected sun‐to‐shade acclimation but over the space of < 10 cm. Respiration, Ic, Ik, and Pmax values were significantly lower in tissues from the understory relative to tissues from the canopy of L. mcdermidiae, while photosystem I (PS I) sizes (PSU I) were significantly higher in tissues from understory microsites. Quantum efficiency was unchanged. Ahnfeltiopsis concinna, in contrast, exhibited higher α in tissues from understory rather than canopy microsites. The values of Pmax for tissues from the canopy of A. concinna were not higher than the understory, while PSU O2(PS II size) of tissues from canopy microsites were unusually higher than those of understory microsites. These characteristics suggest a high degree of irradiance stress in tissues from the canopy of A. concinna, the highest tidal alga in Hawaiian coastal zones. Acclimation to high photosynthetically active radiation and ultraviolet irradiance levels especially in tropical regions appears to be an essential mechanism(s) for stress resistance and persistence of intertidal algae. Algal turfs acclimate at microscales in part fostered by their dense stands that create sharp irradiance gradients as well as adjust physiologically to canopy irradiance levels as mechanisms for optimal photosynthetic performance and stress tolerance.
PURIFICATION AND CHARACTERIZATION OF GLYCOLATE OXIDASE FROM THE BROWN ALGA SPATOGLOSSUM PACIFICISM (PHAEOPHYTA)1
Authors: Iwamoto Koji , Suzuki Kensaku , Ikawa Tomoyoshi
Published: October 2004

Glycolate oxidase was purified to apparent homogeneity from the brown alga Spatoglossum pacificum Yendo. The 1326‐fold purified glycolate oxidase enzyme exhibited a specific activity of 22. 4 micromoles glyoxylate formed ·min−1·mg protein−1. The molecular weight of the native enzyme was estimated to be 230,000 by gel filtration. The subunit molecular weight of the enzyme was determined to be 49,000 by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, suggesting that the native enzyme is a tetramer. There were two absorption peaks at 345 and 445 nm, indicating that glycolate oxidase is a flavoprotein. This enzyme had a high isoelectric point (pI 9.6) and a high pH optimum (pH 8.3). The Km values for glycolate and l‐lactate were 0.49 and 5.5 mM, respectively. This enzyme also had a broad specificity for other straight‐chain α‐hydroxy acids but not for β‐hydroxyacids. Cyanide, azide, N‐ethylmaleimide, and p‐chloromercuribenzoic acid did not affect the enzyme, whereas 2‐pyridylhydroxymethanesulfonic acid strongly inhibited it. These properties of glycolate oxidase from the brown alga S. pacificum are similar to the properties of the glycolate oxidasesfrom higher plants. Polyclonal antibodies raised against the polypeptide fragment of Spatoglossum glycolate oxidase could recognize glycolate oxidase from Spinacia oleracea L., although the cross‐reactivity was weak. The N‐terminal sequence of two internal polypeptide fragments of the enzyme from S. pacificum showed a high degree of similarity to that of glycolate oxidase from higher plants. These results suggest that glycolate oxidase from higher plants and brown algae share the same ancestral protein.
INORGANIC CARBON TRANSPORT IN RELATION TO CULTURE AGE AND INORGANIC CARBON CONCENTRATION IN A HIGH‐CALCIFYING STRAIN OF EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE)1
Authors: Nimer Nabil A. , Merrett Michael J. , Brownlee Colin
Published: October 2004

The relationships among inorganic carbon transport, bicarbonate availability, intracellular pH, and culture age were investigated in high‐calcifying cultures of Emiliania huxleyi (Lohmann) Hay & Mohler. Measurement of inorganic carbon transport by the silicone‐oil centrifugation technique demonstrated that gadolinium, a potential Ca2+ channel inhibitor, blocked intracellular inorganic carbon uptake and photosynthetic 14CO2+ fixation in exponential‐phase cells. In stationary‐phase cells, the intracellular inorganic carbon concentration was unaffected by gadolinium. Gadolinium was also used to investigate the link between bicarbonate and Ca2+ transport in high‐calcifying cells of E. huxleyi. Bicarbonate availability had significant and rapid effects on pHi in exponential‐ but not in stationary‐phase cells. 4′, 4′‐Diisothiocyanostilbene‐2,2′‐disulfonic acid did not block bicarbonate uptake from the external medium by exponential‐phase cells. Inorganic carbon utilization by exponential‐ and stationary‐phase cells of Emiliania huxleyi was investigated using a pH drift technique in a closed system. Light‐dependent alkalization of the medium by stationary‐phase cells resulted in a final pH of 10.1 and was inhibited by dextran‐bound sulphonamide, an inhibitor of external carbonic anhydrase. Exponential‐phase cells did not generate a pH drift. Overall, the results suggest that for high‐calcifying cultures of E. huxleyi the predominant pathway of inorganic carbon utilization differs in exponential and stationary phase cells of the same culture.
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

During 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

Extant 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

A 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

Laboratory 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

Nitrogen 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

A 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

To 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

When 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

Chironomid 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

To 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

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

Photoinhibition 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

The 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

The 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

A 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.
LSU rDNA‐BASED RFLP ASSAYS FOR DISCRIMINATING SPECIES AND STRAINS OF ALEXANDRIUM (DINOPHYCEAE)1
Authors: Scholin Christopher A. , Anderson Donald M.
Published: October 2004

In a previous study large‐subunit ribosomal RNA gene (LSU rDNA) sequences from the marine dinoflagellates Alexandrium tamarense (Lebour) Balech, A. catenella (Whedon et Kofoid) Balech, A. fundyense Balech, A. affine (Fukuyo et Inoue) Balech, A. minutum Halim, A. lusitanicum Balech, and A. andersoni Balech were compared to assess inter‐ and intraspecific relationships. Many cultures compared in that study contained more than one class of LSU rDNA. Sequencing pooled clones of rDNA from single cultures revealed length heterogeneities and sequence ambiguities. This complicated sequence comparisons because multiple rDNA clones from a single culture had to be sequenced individually to document the different classes of molecules present in that culture. A further complication remained as to whether or not the observed intraculture sequence variations were reliable genetic markers or were instead artifacts of the polymerase chain reaction (PCR) amplification, cloning, and/or sequencing methods employed. The goals of the present study were to test the accuracy of Alexandrium LSU rDNA sequences using restriction fragment‐length polymorphism (RFLP) analysis and to devise RFLP‐based assays for discriminating among representatives of that group. Computer‐assisted examination of the sequences allowed us to identify a set of restriction enzymes that were predicted to reveal species, strain, and intraculture LSU rDNA heterogeneities. All groups identified by sequencing were revealed independently and repeatedly by RFLP analysis of PCR‐amplified material. Five ambiguities and one length heterogeneity, each of which ascribes a unique group of Alexandrium species or strains, were confirmed by restriction digests. Observed intraculture LSU rDNA heterogeneities were not artifacts of cloning and sequencing but were instead a good representation of the spectrum of molecules amplified during PCR reactions. Intraculture LSU rDNA heterogeneities thus serve as unique genetic markers for particular strains of Alexandrium, particularly those of A. tamarense, A. catenella, and A. fundyense. However, some of these “signature heterogeneities” represented a smaller portion of PCR product than was expected given acquired sequences. Other deviations from predicted RFLP patterns included incomplete digestions and appearance of spurious products. These observations indicate that the diversity of sequences in PCR product pools were greater than that observed by cloning and sequencing. The RFLP tests described here are useful tools for characterizing Alexandrium LSU rDNA to define the evolutionary lineage of cultures and are applicable at a fraction of the time, cost, and labor required for sequencing.
PHYSIOLOGICAL CHARACTERISTICS OF SPIRULINA PLATENSIS (CYANOBACTERIA) CULTURED AT ULTRAHIGH CELL DENSITIES1
Authors: Qiang Hu , Guterman Hugo , Richmond Amos
Published: October 2004

Photosynthetic activity and growth physiology of Spirulina platensis (Nordstedt) Geitler cultures maintained at ultrahigh cell densities (i.e. above 100 mg chlorophyll‐L−1) in a newly designed photobioreactor were investigated. Nitrogen (NaNO3) in standard Zarouk medium was characterized as a major nutrient‐limiting factor in such cultures. The effect of ultrahigh cell density on photoinhibition of photosynthesis, as reflected by chlorophyll fluorescence and photosynthetic oxygen evolution, was studied: elevating the population density may arrest photoinhibition induced by high photon flux density, as well as low temperature. The relationship between incident irradiance and oxygen production rate was linear in situ for cultures at the optimal cell density, indicating that light limitation rather than light saturation or photoinhibition is the dominant condition outdoors in cultures of ultrahigh cell densities.

In contrast with other reports, the extent of biomass loss at night due mainly to dark respiration was found to be relatively small when cell density was optimal, exerting only a minor effect on overall net productivity. Measurements of oxygen consumption at night revealed low rates of respiration, which may be explained by the low value of the volumetric mass transfer coefficient (KLa) of oxygen. Hence, reduced oxygen tension may play a role in preventing full expression of the respiratory potential in ultrahigh cell density cultures in which photoadaptive strategy may explain cell composition. Ultrahigh cell densities optimized with respect to the intensity of the light source, the length of the light path, and the extent of stirring represent the key for obtaining high output rates of cell mass and some natural products.
Safety of Dobutamine Stress Transesophageal Echocardiography in Obese Patients for Evaluation of Potential Ischemic Heart Disease
Authors: Siddiqui Tariq S. , Stoddard Marcus F.
Published: October 2004

The purpose of this study was to determine the safety of dobutamine stress transesophageal echocardiography (DS‐TEE) in the evaluation of potential coronary artery disease in obese patients. Obese patients tend to have a higher prevalence of hypertension, coronary artery disease, and sleep apnea conditions that could potentially predispose to complications during endoscopic procedures such as DS‐TEE. In addition, obese patients are more likely to have oxygen desaturation during upper gastrointestinal endoscopy. Thus, the safety of DS‐TEE in 90 obese patients (body mass index (BMI) ≥ 27.5 kg/m2) and 86 nonobese patients (BMI < 27.5 kg/m2) was compared. Minor complications (i.e., complications of transient duration and requiring no or only simple intervention) occurred with almost equal frequency in the nonobese and obese groups (28% vs. 29%, P = ns). Transient hypotension was observed in 9% of the obese group compared to 22% in the nonobese group (P < 0.025). However, transient hypertension was noted in 20% of the obese patients compared to 6% in the nonobese group (P < 0.01). A major complication occurred in three obese patients (3.3%), which included hypotension, marked elevation of systolic blood pressure, or ventricular fibrillation. Four patients (4.7%, P = ns) of the nonobese group had a major complication, which included sustained ventricular tachycardia in one, hypertension in one, and hypotension in two patients. No deaths occurred in either group. Although obesity should remain a consideration in the risk assessment of whether or not to perform DS‐TEE, when proper precautions are instituted DS‐TEE appears equally safe in obese as compared to nonobese patients.
Hemodynamic Instability After Receiving Intravenous Perflutren for Contrast Echocardiography in an Elderly Female
Authors: Blokh Ilya , Ganem Amanda , Bonaros Elias P. , Stephen Bibiana D. , Steinberg Bart , Rosen Stacey E.
Published: October 2004

Myocardial contrast echocardiography (MCE) has been used with increasing frequency and is considered a safe way to improve left ventricular border opacification. Studies have consistently documented that MCE can improve the ability to assess both global and regional left ventricular function by echocardiography. We report the case of an 83‐year‐old female who developed immediate and sustained hemodynamic instability after the injection of Perflutren for a contrast echocardiogram. We reviewed the literature and found no such previous reactions with Perflutren. Based on the temporal sequence of hypotension following Perflutren injection along with other clinical data, we concluded that our patient's hemodynamic instability was most likely secondary to an anaphylactic reaction.
Large Atrial Appendage Thrombus in the Presence of Severe Mitral Regurgitation: Contradictory Hemodynamics or Expected Findings
Authors: López‐Candales Angel , Edelman Kathy L.
Published: October 2004

A case of a large left atrial appendage thrombus in the presence of severe mitral regurgitation is presented. The use of transesophageal echocardiography in this setting was not only useful but also crucial despite the low anticipated diagnostic yield given the expected altered left atrial flow dynamics from the turbulent regurgitant lesion. However, additional confounding factors could have acted as potential mechanisms to enhance thrombosis in this setting and consequently are discussed.
Transesophageal Investigation of Surgically Ligated Left Atrial Appendage
Authors: Oneglia Carlo , Muneretto Claudio , Rusconi Cesare
Published: October 2004

Surgical ligation of the left atrial appendage is often performed during heart surgery for various diseases like mitral prosthesis implantation, mitral valve repair, and even coronary artery revascularization, mainly to prevent thrombus formation and systemic embolism in patients with atrial fibrillation. However surgical ligation is sometimes incomplete, thereby exposing the patient to residual embolic risk. We report two cases of surgical ligation of the left atrial appendage focusing on the transesophageal echographic aspects of complete or incomplete closure of the appendage.
Analysis of Left Atrial Volume Change Rate for Evaluation of Left Ventricular Diastolic Function
Authors: Hung Ming‐Jui , Cherng Wen‐Jin
Published: October 2004

An excellent correlation exists between the change in the left atrial (LA) angiographic area and posterior aortic wall motion. The aim of the study was to define the role of posterior aortic wall motion, indicating LA volume change, during the left ventricular (LV) phase for the assessment of LV diastolic function. A total of 155 patients underwent echocardiography after cardiac catheterization. Study patients were classified into four groups according to the ratio of early‐to‐late transmitral flow velocity (E/A ratio) and/or LV end‐diastolic pressure (EDP): 42 patients with LVEDP < 15 mmHg and E/A ratio >1 (normal filling); 46 patients with E/A < 1 (impaired relaxation); 46 patients with LVEDP ≥ 15 mmHg and E/A > 1 and <2 (pseudonormal filling); 21 patients with E/A > 2, E ≥ 70 cm/s, and E‐wave deceleration time ≤160 ms (restrictive filling). The slopes of early and late (slopes E and A) diastolic motion of LA wall were derived from M‐mode analysis, together with the LV isovolumic time constant Tau from cardiac catheterization. Values of slope E/A decreased in restrictive filling, pseudonormal filling, and impaired relaxation as compared with normal filling (0.41 ± 0.14, 0.69 ± 0.15, and 0.56 ± 0.23 vs 1.25 ± 0.26, P < 0.001, respectively) and correlated inversely with the isovolumic time constant Tau (r = 0.79, P < 0.001). In cases for which a value of slope E/A < 1 was obtained, indicating a relaxation abnormality, the M‐mode derived pattern of LA wall motion identified the underlying abnormal LV diastolic function with a sensitivity of 98.3%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 95.2%. Analysis of the slope of LA wall motion, indicating LA volume change rate, during LV diastolic phase is useful in evaluating LV diastolic function. It provides a new noninvasive index that correlates well with invasive index of LV relaxation.
Live Three‐Dimensional Transthoracic Echocardiographic Assessment of Isolated Cleft Mitral Valve
Authors: Sinha Ashish , Kasliwal Ravi R. , Nanda Navin C. , Chauhan Nagendra , Agrawal Gopal , Khanna Deepak , Dod Harvinder S.
Published: October 2004

We report the usefulness of live three‐dimensional transthoracic echocardiography in the comprehensive assessment of isolated cleft mitral valve in two adult patients studied by us.
Morphological Assessment of Left Ventricular Thrombus by Live Three‐Dimensional Transthoracic Echocardiography
Authors: Sinha Ashish , Nanda Navin C. , Khanna Deepak , Dod Harvinder S. , Vengala Srinivas , Mehmood Farhat , Agrawal Gopal , Upendram Sailendra
Published: October 2004

We report the usefulness of live three‐dimensional transthoracic echocardiography (3DTTE) in the morphological assessment of a left ventricular thrombus. Using live 3DTTE, the thrombus could be easily viewed end‐on and from the sides. In addition, by cropping the 3D images sequentially in transverse (horizontal or short axis), longitudinal (vertical or long axis), frontal, and oblique planes, the degree and extent of lysis within the thrombus, which represents an integral part of the clot‐resolution process, could be comprehensively assessed. The site of attachment of the thrombus in the left ventricular apex and its morphology could also be fully evaluated in three dimensions by live 3DTTE.
An infectious aetiology for childhood acute leukaemia: a review of the evidence
Authors: McNally Richard J. Q. , Eden Tim O. B.
Published: October 2004

There are three current hypotheses concerning infectious mechanisms in the aetiology of childhood leukaemia: exposure in utero or around the time of birth, delayed exposure beyond the first year of life to common infections and unusual population mixing. No specific virus has been definitively linked with childhood leukaemia and there is no evidence to date of viral genomic inclusions within leukaemic cells. The case–control and cohort studies have revealed equivocal results. Maternal infection during pregnancy has been linked with increased risk whilst breast feeding and day care attendance in the first year of life appear to be protective. There is inconclusive evidence from studies on early childhood infectious exposures, vaccination and social mixing. Some supportive evidence for an infectious aetiology is provided by the findings of space‐time clustering and seasonal variation. Spatial clustering suggests that higher incidence is confined to specific areas with increased levels of population mixing, particularly in previously isolated populations. Ecological studies have also shown excess incidence with higher population mixing. The marked childhood peak in resource‐rich countries and an increased incidence of the childhood peak in acute lymphoblastic leukaemia (ALL) (occurring at ages 2–6 years predominantly with precursor B‐cell ALL) is supportive of the concept that reduced early infection may play a role. Genetically determined individual response to infection may be critical in the proliferation of preleukaemic clones as evidenced by the human leucocyte antigen class II polymorphic variant association with precursor B‐cell and T‐cell ALL.
Possibilities for tailored and targeted therapy in paediatric acute myeloid leukaemia
Authors: Zwaan Ch. M. , Kaspers G. J. L.
Published: October 2004

The clinical outcome of acute myeloid leukaemia (AML) in children has improved considerably using intensive chemotherapy and/or stem cell transplantation. This leads to cure in 50–70% of patients, and also results in significant morbidity and mortality. Hence, we need other ways to improve the cure rate. This review discusses possibilities for tailored therapy, reviewing in vitro cellular drug sensitivity data. The results provide suggestions regarding the adaptation of clinical protocols in certain AML subgroups, although further clinical studies will show whether this is effective. Secondly, we review type 1 genetic abnormalities (such as receptor tyrosine kinase mutations) that result in enhanced survival and proliferation of leukaemic cells, which can be detected in approximately 50% of paediatric AML samples, and are non‐randomly associated with French–American–British type and cytogenetic subgroups. FLT3 internal tandem duplication is associated with poor clinical outcome, and may be used for risk‐group stratification. The first results with small molecule inhibitors in adult AML do not suggest their use in children as yet. International collaboration is needed to further improve outcome by developing treatment protocols for subgroups of paediatric AML.
Multiple myeloma involving central nervous system: high frequency of chromosome 17p13.1 (p53) deletions
Authors: Chang Hong , Sloan Stephen , Li Dan , Keith Stewart A.
Published: October 2004

Central nervous system (CNS) involvement is an unusual manifestation in multiple myeloma (MM). The molecular basis of CNS myeloma is poorly understood. MM is characterized by translocations involving the immunoglobulin heavy chain (IgH) locus and frequent 13q deletions. Alterations of p53 or c‐myc in MM may represent secondary changes associated with disease progression. We investigated nine patients with CNS MM using interphase fluorescence in situ hybridization (FISH) combined with immunofluorescence detection of the cytoplasmic light chain (cIg‐FISH) for the presence of above genomic aberrations. Of nine patients studied, eight cases had hemizygous p53 deletion and 4 had 13q deletions. Of the patients with 13q deletions, two had IgH translocations, one involving 4p16.3 (FGFR3), the other involving 16q23 (c‐maf). The high incidence of p53 deletions detected by cIg‐FISH in CNS myeloma may be a marker for chromosomal instability, and may be associated with metastatic features of myeloma cells.