bluuebunny/crossref_metadata_2025 huggingface dataset:
The production of extracellular carbohydrates by estuarine benthic diatoms: the effects of growth phase and light and dark treatment
Authors: Smith David J. , Underwood Graham J. C.
Published: March 2003

Epipelic diatoms are important constituents of estuarine microphytobenthic biofilms. Field‐based investigations have shown that the production of carbohydrates by such taxa is ecologically important. However, limited information exists on the dynamics of carbohydrate production by individual species of epipelic diatoms. The production of low and high molecular weight extracellular carbohydrates in axenic cultures of five species of benthic estuarine diatoms, Cylindrotheca closterium (Ehrenberg), Navicula perminuta (Grun.) in Van Heurck, Nitzschia frustulum (Kütz.) Grunow, Nitzschia sigma (Kütz.) Grunow, and Surirella ovata (Kütz.) Grunow, were investigated. All species produced colloidal (water‐soluble) carbohydrates during growth, with maximal production occurring during stationary phase. During logarithmic growth, approximately 20% of extracellular carbohydrates consisted of polymeric material (extracellular polymeric substances [EPS]), but during stationary phase, EPS content increased to 34%–50%. Pyrolysis–mass spectrophotometry analysis showed differences in the composition of EPS produced during logarithmic and stationary phase. All species synthesized glucan as a storage carbohydrate, with maximum glucan accumulation during the transition from log to stationary phase. Short‐term labeling with 14C‐bicarbonate found that between 30 and 60% of photoassimilates were released as colloidal carbohydrate, with EPS consisting of approximately 16% of this colloidal fraction. When cells were placed in darkness, EPS production increased, and between 85 and 99% of extracellular carbohydrate produced was polymeric. Glucan reserves were utilized in dark conditions, with significant negative correlations between EPS and glucan for N. perminuta and S. ovata. Under dark conditions, cells continued to produce EPS for up to 3 days, although release of low molecular weight carbohydrates rapidly ceased when cells were dark treated. Three aspects of EPS production have been identified during this investigation: (1) production during rapid growth, which differs in composition from (2) EPS directly produced as a result of photosynthetic overflow during growth limiting conditions and (3) EPS produced for up to 3 days in the dark using intracellular storage reserves (glucans). The ecological implications of these patterns of production and utilization are discussed.
THE EFFECT OF IRRADIANCE ON THE GROWTH OF DIFFERENT FORMS OF FRESHWATER DIATOMS: IMPLICATIONS FOR SUCCESSION IN ATTACHED DIATOM COMMUNITIES
Authors: Tuji Akihiro
Published: March 2003

The growth rates of 12 strains of attached freshwater diatoms were examined as a function of irradiance. The results were used to determine physiological parameters in the growth–irradiance relationships. Values of Gmax (maximum growth rate) and I k (irradiance at half of Gmax) correlated with successional phase. The development of attached diatom communities appears to proceed from high irradiance species to low irradiance species that appear later in the successional sequence. Thus, efficiency of light use is linked to successional strategy, as has been documented for terrestrial plants.
MOBILIZATION OF β‐1,3‐GLUCAN AND BIOSYNTHESIS OF AMINO ACIDS INDUCED BY NH4+ ADDITION TO N‐LIMITED CELLS OF THE MARINE DIATOM SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)
Authors: Granum Espen , Myklestad Sverre M.
Published: March 2003

Mobilization of the reserve β‐1,3‐glucan (chrysolaminaran) in N‐limited cells of the marine diatom Skeletonema costatum (Grev.) Cleve (Bacillariophyceae) was investigated. The diatom was grown in pH‐regulated batch cultures with a 14:10‐h light:dark cycle until N depletion. In a pulse‐chase experiment, the cells were first incubated in high light (200 μmol photons·m−2·s−1) with 14C‐bicarbonate until dissolved inorganic carbon was exhausted. Unlabeled bicarbonate (1 mM) was then added, and the cells were incubated in the dark and subsequently in low light (20 μmol photons·m−2·s−1) with additions of 40 μM NH4+. In the 14C pulse phase with high light and N depletion, β‐1,3‐glucan accumulated and accounted for 85% of incorporated 14C. In the subsequent 14C chase phases, added NH4+ was assimilated at an N‐specific rate of 0.11 h−1 in both the dark and low light, and in both cases it caused a significant mobilization of β‐1,3‐glucan (dark, 26%; low light, 19%). Biochemical fractionation of organic 14C showed that free amino acids were most rapidly labeled in the early stage of NH4+ assimilation, whereas proteins and polysaccharides were labeled more rapidly after 1.2 h. Analysis of the cellular free amino acids strongly indicated that de novo biosynthesis was occurring, with a Gln:Glu ratio increasing from 0.4 to 10 within 1.2 h. After the NH4+ was exhausted, the cellular pools of glucan and amino acids became constant or slowly decreased. In another experiment, N‐limited cells were first incubated in high light until dissolved inorganic carbon was exhausted and were further incubated in high light with 150 μM NH4+ under inorganic carbon limitation. Added NH4+ was assimilated at an N‐specific rate of 0.023 h−1, and cellular β‐1,3‐glucan decreased by 15% within 6 h. Hence, β‐1,3‐glucan was mobilized during NH4+ assimilation, even though inorganic carbon was modifying the metabolic rates. The results provide new evidence of β‐1,3‐glucan supplying essential precursors for biosynthesis of amino acids and other components in S. costatum in both the dark and subsaturating light and even saturating light under inorganic carbon limitation.
SYSTEMATICS OF THE DELESSERIACEAE (CERAMIALES, RHODOPHYTA) BASED ON LARGE SUBUNIT rDNA AND rbcL SEQUENCES, INCLUDING THE PHYCODRYOIDEAE, SUBFAM. NOV.
Authors: Lin Showe‐Mei , Fredericq Suzanne , Hommersand Max H.
Published: March 2003

The present classification of the Delesseriaceae retains the essential features of Kylin's system, which recognizes two subfamilies Delesserioideae and Nitophylloideae and a series of “groups” or tribes. In this study we test the Kylin system based on phylogenetic parsimony and distance analyses inferred from two molecular data sets and morphological evidence. A set of 72 delesseriacean and 7 additional taxa in the order Ceramiales was sequenced in the large subunit rDNA and rbcL analyses. Three large clades were identified in both the separate and combined data sets, one of which corresponds to the Delesserioideae, one to a narrowly circumscribed Nitophylloideae, and one to the Phycodryoideae, subfam. nov., comprising the remainder of the Nitophylloideae sensu Kylin. Two additional trees inferred from rbcL sequences are included to provide broader coverage of relationships among some Delesserioideae and Phycodryoideae. Belonging to the Delesserioideae are the Caloglosseae with Caloglossa; an expanded Hemineureae that includes Hemineura, Patulophycus, Marionella, Laingia, Botryocarpa, and Pseudophycodrys; the Delesserieae with Delesseria and Membranoptera; the Apoglosseae with Apoglossum and a group of southern hemisphere species presently placed in Delesseria that belong in Paraglossum; the Hypoglosseae with Hypoglossum, Branchioglossum, Zellera, and Bartoniella; and the Grinnellieae with Grinnellia. The revised Nitophylloideae contains the Nitophylleae with Nitophyllum, Valeriemaya, Polyneuropsis, and Calonitophyllum and the Martensieae with Opephyllum and Martensia. A new subfamily, Phycodryoideae, is proposed to include the Phycodryeae with Phycodrys, Polyneura, Nienburgia, Cladodonta, Heterodoxia, and Womersleya; the Cryptopleureae with Cryptopleura, Hymenena, Acrosorium, and Botryoglossum; the Myriogrammeae with Myriogramme and Haraldiophyllum; and the Schizoserideae with Schizoseris, Neuroglossum, Drachiella, Abroteia, and species from South America placed in Platyclinia. This research promotes the correlation of molecular and morphological phylogenies.
ALGAL MODEL SYSTEMS AND THE ELUCIDATION OF PHOTOSYNTHETIC METABOLISM
Authors: Raven John A. , Girard‐Bascou Jacqueline
Published: March 2003

The main impact of algal investigations on a wider understanding of photosynthesis in O2evolvers has come about through studies on microalgae. Experiments with flashing light led to the concepts of photo‐ synthetic units and reaction centers. Work on photon yields and the Emerson enhancement effect with fluorescence and spectroscopy, as well as investigations with mutants, were crucial in elaborating and then testing the validity of the Z scheme for light reactions. The carbon reduction (or Calvin) cycle was discovered using14C, chromatography, andChlorella(plusScenedesmus). The availability of complete gene sequences for several cyanobacteria and the flowering plantArabidopsisand very soon for the eukaryotic algaChlamydomonaspermit important advances in our understanding of photosynthesis in all these organisms. Eukaryotic microalgae and cyanobacteria remain advantageous in fundamental photosynthetic studies.
IMPACT OF IRON LIMITATION ON THE PHOTOSYNTHETIC APPARATUS OF THE DIATOM CHAETOCEROS MUELLERI (BACILLARIOPHYCEAE)
Authors: Davey Margaret , Geider Richard J.
Published: March 2003

Iron starvation induced marked increases in flavodoxin abundance and decreases in light‐saturated and light‐limited photosynthesis rates in the diatom Chaetoceros muelleri. Consistent with the substitution of flavodoxin for ferredoxin as an early response to iron starvation, increases of flavodoxin abundance were observed before declines of cell division rate or chl a specific photosynthesis rates. Changes in the abundance of flavodoxin after the addition of iron to iron‐starved cells indicated that flavodoxin was not actively degraded under iron‐replete conditions. Greater declines in light‐saturated oxygen evolution rates than dark oxygen consumption rates indicated that the mitochondrial electron transfer chain was not affected as greatly by iron starvation as the photosynthetic electron transfer chain. The carbon:nitrogen ratio was unaffected by iron starvation, suggesting that photosynthetic electron transfer was a primary target of iron starvation and that reductions in nitrate assimilation were due to energy limitation (the C:N ratio would be expected to rise under nitrogen‐limited but energy‐replete conditions). Parallel changes were observed in the maximum light‐saturated photosynthesis rate and the light‐limited initial slope of the photosynthesis‐light curve during iron starvation and recovery. The lowest photosynthesis rates were observed in iron‐starved cells and the highest values in iron‐replete cells. The light saturation parameter, Ik, was not affected by iron starvation, nor was the chl‐to‐C ratio markedly reduced. These observations were consistent with iron starvation having a similar or greater effect on photochemical charge separation in PSII than on downstream electron transfer steps. Declines of the ratio of variable to maximum fluorescence in iron‐starved cells were consistent with PSII being a primary target of iron starvation. The functional cross‐section of PSII was affected only marginally (<20%) by iron starvation, with the largest values observed in iron‐starved cells. The rate constant for electron transfer calculated from fast repetition rate fluorescence was found to covary with the light‐saturated photosynthesis rate; it was lowest in the most severely starved cells.
TAXONOMY OFADAMSIELLAL.E. PHILLIPS ET W.A. NELSON, GEN. NOV. ANDEPIGLOSSUMKÜTZING (RHODOMELACEAE, CERAMIALES)1
Authors: Phillips Louise E.
Published: March 2003

In a taxonomic/phylogenetic study of the genusLenormandia, several species were found to differ significantly from the type species,L. spectabilisSonder, in apical morphology, blade‐surface pattern, medullary construction, the presence of pseudopericentral cells, and the position of reproductive structures. These species constitute two groups that differ morphologically, a finding largely supported by analysis of 18S rRNA sequences, as reported previously. The two putativeLenormandiaspecies from New Zealand, along with two previously undescribed species also from New Zealand, comprised one such group, designated here by the new genus nameAdamsiellaL.E. PhillipsetW.A. Nelson, gen. nov. and includingA. melchioriL.E. PhillipsetW.A. Nelson, sp. nov.,A. lorataL.E. PhillipsetW.A. Nelson, sp. nov.,A. angustifolia(Harvey) L.E. PhillipsetW.A. Nelson, comb. nov., andA. chauvinii(Harvey) L.E. PhillipsetW.A. Nelson comb. nov.Adamsielladiffers fromLenormandiaby incurved apices, a chevron surface pattern, and reproductive structures on dorsi‐ventrally flattened apically incurved polysiphonous branchlets usually produced at the margins. Two species endemic to Australia formed the second group designated by the resurrected generic nameEpiglossumand also characterized by a strongly incurved apex and chevron surface pattern but with reproductive structures produced on terete polysiphonous branchlets found either on the midrib or elsewhere on the blade surface but not the margins.EpiglossumcontainsE. smithiae(J.D. HookeretHarvey) Kützing andE. proliferum(C. Agardh) L.E. Phillips, comb. nov.
REMARKABLE CONSERVATION OF INTERNALLY TRANSCRIBED SPACER SEQUENCES OF ARTHROSPIRA (“SPIRULINA” ) (CYANOPHYCEAE, CYANOBACTERIA) STRAINS FROM FOUR CONTINENTS AND OF RECENT AND 30‐YEAR‐OLD DRIED SAMPLES FROM AFRICA1
Authors: Baurain Denis , Renquin Laurent , Grubisic Stana , Scheldeman Patsy , Belay Amha , Wilmotte Annick
Published: March 2003

The internally transcribed spacer (ITS) sequences of 21 Arthrospira clonal strains from four continents and assigned to four different species (A. platensis, A. maxima, A. fusiformis, A. indica) in the culture collections were determined. Two main clusters, I and II, were differentiated by 49 positions out of 475 nt or 477 nt, respectively. Each cluster was further subdivided into two subclusters. Subclusters I.A and I.B were separated by two substitutions, whereas subclusters II.A and II.B were distinguished by four substitutions. After direct sequencing of the PCR products, three dried samples from Chad aged between 3 months and 35 years yielded a sequence belonging to subcluster I.A, as did a recent commercial product. The strains grown in production plants belonged to the same (sub)clusters as strains from culture collections, mainly I.A and II. PCR primers specific for each cluster and subcluster were designed and tested with crude cell lysates of Arthrospira strains. One dried sample (“dihé” 1) and a herbarium sample from Lake Sonachi (Kenya) only contained I.A sequences, whereas the commercial product was a mixture of the four genotypes and the other two dried samples contained minor polymorphisms characteristic of different clusters. Five clonal Arthrospira strains, thought to be duplicates, showed the simultaneous presence of the two forms of the four diagnostic positions that distinguish subclusters genotype II.A and genotype II.B. This is likely to be caused by multiple copies of the rDNA operon, in a intermediate stage of homogenization between subcluster II.A and subcluster II.B. The high conservation of ITS sequences is in contrast with the assignment to four different species, the great morphological variability of the strains, and their wide geographic distribution.
GENETIC DIFFERENCES BETWEEN TWO GROWTH‐FORMS OF LITHOPHYLLUM MARGARITAE (RHODOPHYTA) IN BAJA CALIFORNIA SUR, MEXICO1
Authors: Schaeffer Timothy N. , Smith G. Jason , Foster Michael S. , DeTomaso Anthony
Published: March 2003

Unattached, nongeniculate, coralline algae or rhodoliths exhibit a range of morphological variability seemingly dependent on environmental factors. Rhodoliths have an extensive fossil record, and environmentally dependent characteristics make them potentially reliable paleoindicators. Species of the rhodolith‐forming genus Lithophyllum Philippi in Baja California Sur, Mexico were recently consolidated into one species. Under the new classification, L. margaritae (Hariot) Heydrich consists of several growth forms presumably reflecting local environmental conditions. We examined the genetic structure of four populations of this species using amplified fragment length polymorphisms (AFLP) to characterize the extent of genetic variation associated with foliose and fruticose growth forms. AFLP band sharing analysis revealed that foliose growth forms exhibited consistently higher intrapopulation similarities (0.75–0.85) than fruticose growth forms (similarity range, 0.55–0.67). This trend was also evident in comparisons of geographically isolated populations. These data indicate that the two morphologies are genetically distinct and that genetic exchange between foliose and fruticose growth forms of L. margaritae may be limited. Consequently, rhodolith growth forms appear to be the result of an interplay between both genetic makeup and environmental conditions.
ACQUISITION OF INORGANIC CARBON BY THE MARINE HAPTOPHYTE ISOCHRYSIS GALBANA (PRYMNESIOPHYCEAE)1
Authors: Bhatti Shabana , Huertas I. Emma , Colman Brian
Published: March 2003

Inorganic carbon acquisition has been investigated in the marine haptophyte Isochrysis galbana. External carbonic anhydrase (CA) was present in air‐grown (0.034% CO2) cells but completely repressed in high (3%) CO2‐grown cells. External CA was not inhibited by 1.0 mM acetazolamide. The capacity of cells to take up bicarbonate was examined by comparing the rate of photosynthetic O2 evolution with the calculated rate of spontaneous CO2 supply; at pH 8.2 the rates of O2 evolution exceeded the CO2 supply rate 14‐fold, indicating that this alga was able to take up HCO3−. Monitoring CO2 concentrations by mass spectrometry showed that suspensions of high CO2‐grown cells caused a rapid drop in the extracellular CO2 in the light and addition of bovine CA raised the CO2 concentration by restoring the HCO3−‐CO2 equilibrium, indicating that cells were maintaining the CO2 in the medium below its equilibrium value during photosynthesis. A rapid increase in extracellular CO2 concentration occurred on darkening the cells, indicating that the cells had accumulated an internal pool of unfixed inorganic carbon. Active CO2 uptake was blocked by the photosynthetic electron transport inhibitor 3‐(3′,4′‐dichlorphenyl)‐1,1‐dimethylurea, indicating that CO2 transport was supported by photosynthetic reactions. These results demonstrate that this species has the capacity to take up HCO3− and CO2 actively as sources of substrate for photosynthesis and that inorganic carbon transport is not repressed by growth on high CO2, although external CA expression is regulated by CO2 concentration.
THE INVOLVEMENT OF A PLASMA MEMBRANE H+‐ATPase IN THE BLUE‐LIGHT ENHANCEMENT OF PHOTOSYNTHESIS IN LAMINARIA DIGITATA (PHAEOPHYTA)1
Authors: Klenell Markus , Snoeijs Pauli , Pedersén Marianne
Published: March 2003

Many brown algae, including the kelp Laminaria digitata (Huds.) Lamour., exhibit enhanced photosynthesis when they are given a small amount of blue‐light in addition to a background of saturating red light. This blue light effect is correlated with an increased uptake of carbon. In the present study, we tested the hypothesis that blue light acts by increasing the activity of a plasma membrane H+‐ATPase, thereby promoting an active carbon uptake across the plasma membrane. Photosynthetic carbon uptake was studied in pH‐drift experiments under illumination with red and blue light and using different inhibitors. Vanadate, an inhibitor of plasma membrane H+‐ATPases, had a minor inhibitory effect on carbon uptake rates under saturating red light conditions, but inhibited the blue‐light enhancement by approximately 60%. An inhibitor of external carbonic anhydrase, acetazolamide, decreased the carbon uptake in both red light and in red plus blue light by 48% and 68%, respectively. These results suggest that photosynthetic carbon uptake depends on an external carbonic anhydrase under both red and red plus blue light conditions, and that blue light induces an increased activity of a P‐type H+‐ATPase in the plasma membrane. The proton buffer Tris, which has a buffering capacity similar to vanadate in seawater, had no inhibitory effect on carbon uptake rates neither in red light nor in red plus blue light, showing that the inhibitory effect of vanadate is not caused by its effect as a buffer. The blue‐light enhancement was also abolished by a protein kinase inhibitor (H‐7), suggesting that the transduction of the blue‐light signal involves a protein kinase, which activates the plasma membrane H+‐ATPase by phosphorylation.
EVIDENCE FOR KINESIN‐ AND DYNEIN‐LIKE PROTEIN FUNCTION IN CIRCULAR NUCLEAR MIGRATION IN THE GREEN ALGA PLEURENTERIUM TUMIDUM: DIGITAL TIME LAPSE ANALYSIS OF INHIBITOR EFFECTS1
Authors: Holzinger Andreas , Lütz‐Meindl Ursula
Published: March 2003

The unicellular green alga Pleurenterium tumidum Bréb. performs a unique type of circular nuclear migration, wherein the nucleus leaves its central position and starts revolutions in the cortical isthmus area about 10 h after mitosis. This motion lasts for at least 12 h with an average velocity of about 1 h per revolution. Possible force generation modes during circular nuclear migration of Pleurenterium were investigated by application of inhibitors and the use of digital time‐lapse video microscopy. 5′‐Adenylylimidodiphosphate, a nonhydrolyzable nucleotide analogue, retarded or inhibited circular nuclear migration, suggesting that ATPase dependent motor proteins are involved. Ado‐ ciasulfate‐2, a kinesin specific inhibitor, caused displacement of the nucleus, suggesting that the linkage between the microtubule track and the nucleus is lost. The nucleus was still able to move for short distances, but no normal revolutions took place. Erythro‐9‐[3‐(2‐hydroxynonyl)] adenine, a dynein ATPase inhibitor, led to complete inhibition of nuclear revolutions, suggesting a function in force generation also for this molecular motor. In addition, kinesin‐ and dynein‐like proteins were detected in Pleurenterium extracts by Western blotting. The myosin specific inhibitor 2,3‐butanedione 2‐monoxime did not influence circular nuclear migration in Pleurenterium. This result and the absence of actin filaments around the migrating nucleus as depicted by means of microinjection of Alexa phalloidin in the present study indicate that the actin‐myosin system can be excluded from force generation.
Phytoplankton of a Mississippi River Watershed in Coastal Louisiana
Authors: Ciugulea I. I. , Waters D. A. , Day J. W. , Chapman R. L.
Published: March 2003

In July–August 2001, phytoplankton samples were collected from a coastal marsh south of New Orleans, LA. This wetland area is usually cut off from the Mississippi River by levees and other flood control devices, but periodically the Caernarvon Diversion is opened to allow fresh river water to flow into the marsh. As part of a larger project, the present study seeks to determine the affect the periodic input of freshwater has on phytoplankton dynamics in the Caernarvon Diversion watershed. The first phase of the project ‐ collecting and identifying algae during the summer when the Caernarvon Diversion is kept closed ‐ has been completed. A total of 168 species from 76 genera representing 8 phyla were identified and digital images recorded. Little or no previously published data on the taxonomy and ecology of phytoplankton from this area are available. Sampling in spring 2002, when the diversion is open, will allow comparative analysis of phytoplankton composition and productivity. In a collaborative study, the phytoplankton data will be combined with information on nutrients, chlorophyll a, turbidity, salinity, etc. and used in a model to demonstrate how the ecosystem is affected by the diversion. Also, a database of digital images is available at http://www.chapman.lsu.edu/digitalalgae. In addition to the taxonomic identification data and images, the site will eventually include physico‐chemical and GIS data on the collection sites. Supported in part by a grant from the Office of Sea Grant Development at LSU.
One Small Step: Why Did the Charophytes Have the Right Stuff?
Authors: Delwiche C. F. , Karol K. G. , McCourt R. M.
Published: March 2003

The origin and evolution of land plants (i.e. embryophytes) represents one of the seminal events in the history of life on earth. When the land plant lineage took hold upon the continents, there were profound changes in the global environment including dramatic modification of the erosion regime, correlated changes in marine nutrient inputs, and striking fluctuations in atmospheric chemistry. These changes took place not only because of the ability of land plants to survive on land, but also because their structure and physiology permitted them to make efficient use of resources, anchor themselves effectively and in so doing stabilize the substrate and permit the formation of modern soils, and maintain metabolic activity for long periods of time even in the absence of rainfall and surface moisture. Molecular phylogenetic analyses show the order Charales is the sister group to all land plants, with the Coleochaetales sister to the land plant/Charales lineage. Thus, in a very real sense, the embryophytes are ‘drier algae.’ Many groups of green algae live in the terrestrial environment, but only one of these – the land plants – has radiated into a wide range of habitats. It is not known why the land plant lineage has been so successful. Traits that are likely to have played a role in their success include cell wall biochemistry, desiccation resistance and tolerance, structural complexity, and various reproductive strategies. In all probability, the success of the land plant lineage was not the result of a single ‘key innovation’, but an emergent property resulting from complex interactions among these and other features of the lineage. Comparative study of the properties of diverse aquatic and terrestrial algae can be used to identify properties that were important in the colonization of the land and how they interact.
Algal Stimulation of the Berkeley PIT Lake System
Authors: Bartkowiak B. , Mitman G. G.
Published: March 2003

This study was conducted to evaluate four species of algae (Chromulina freiburgensis Dofl., Chlorella ellipsoidea Gerneck, C. vulgaris Beijerinck, and Chlamydomonas acidophila Negoro) isolated from an acid pit lake for their bioremediative potential. The Berkeley Pit Lake system, located in Butte, MT, USA is an abandoned open‐pit mine. As a result of acid rock drainage the water in this pit is very acidic and contains high concentrations of dissolved metals. First, optimal nutrient levels for each species of algae were determined. Levels of nutrients tested include: 5, 10, 15 mg N/L, and 0, 3, 6 mg P/L. The experiment was conducted with sterile filtered Berkeley Pit water. Next, each species of algae were grown under optimal nutrient levels and dissolved metal removal potentials were examined, using Inductively‐Coupled Plasma–Atomic Emission Spectrometry (ICP–AES). In addition, field sampling was preformed to gain a better understanding of the microbial community within the pit. Finally, field parameters including, light, temperature, dissolved oxygen, specific conductivity, redox potential, and turbidity were examined to determine the actual conditions for microbial growth within the Berkeley pit.
The Aquaculture of Porphyra Leucosticta (Rhodophyta) for an Integrated Finfish/Seaweed Recirculating Aquaculture System in an Urban Application
Authors: Yarish C. , He P. , Carmona R. , Liu S. , Kraemer G. , Neefus C. , Chopin T. , Nardi G. , Curtis J. , Lonergan S. , Trupp P.
Published: March 2003

Aquaculture represents an excellent opportunity to help rejuvenate blighted coastal urban areas on the north‐east coast. Aquaculture requires relatively little space, often acquired at reduced cost in ungentrified city areas, and can represent an attractive, environmentally benign form of commerce. However, finfish and shellfish aquaculture operations are a source of an effluent with high concentrations of dissolved inorganic nutrients (N, P). To prevent eutrophication, the EPA is developing stringent guidelines for the release of N and P into coastal waters. An integrated recirculating aquaculture system, coupling the growth of seaweed and fish, can solve these problems for urban aquaculture facilities; not only is the effluent remediated but an additional multiproduct, high‐value crop can be generated. One tank‐based (on land) marine aquaculture operation is GreatBay Aquaculture, LLC (Portsmouth, NH), a land‐based hatchery and grow‐out facility for high value summer flounder and cod. Our work is to develop an integrated finfish/seaweed recirculating aquaculture system (RAS) suitable for urban aquaculture. Our RAS system will integrate the culture of summer flounder and native species of seaweed (i.e. Porphyra). BRVAS students are working along side undergraduate and graduate students in the construction and operation of these systems. There are at least seven recognized species of Porphyra in the north‐east. We have begun mesoscale evaluation of P. leucosticta, since it may be a good candidate for the food (sushi) and for r‐phycoerythrin industries. The mass culture techniques (in both free culture and attached to nets) for this Porphyra species are developing. We will report on the mass seeding technologies that we have developed and the specific growth rates of P. leucosticta at the BRVAS culture facilities.
An Examination of the Effects of a Reservoir, Lake Ashtabula, on the Periphytic Algae in the Sheyenne River, North Dakota
Authors: Jaskowiak M. A. , Fawley K. P. , Fawley M. W.
Published: March 2003

The Sheyenne River is a third order stream that drains a significant portion of central and eastern North Dakota. In 1950, the Baldhill Dam was built and as a result, the reservoir, Lake Ashtabula, was formed. The periphytic algae in this river were extensively studied from 1997 to 1999. During this research, the effects of differences in environmental variables on the algal communities were assessed with Canonical Correspondence Analysis (CCA). In this analysis, the periphytic algal communities in the downstream sites appeared to be quite different from those communities found upriver of Lake Ashtabula. Other research on different rivers has shown profound changes in the algal community after a dam was built along the river. Redundancy Analysis (RDA) was used to determine if the sites downstream are more statistically similar with Lake Ashtabula than with the upstream sites. Finally, CCA was used to examine which environmental variables explain the most variance in Lake Ashtabula and the downstream sites.
Apoglosseae Trib. Nov. (Delesseriaceae, Rhodophyta) Based on Two Molecular Datasets and Cystocarp Development
Authors: Lin S.‐M. , Fredericq S. , Hommersand M. H.
Published: March 2003

The genus Apoglossum J. Agardh has traditionally been placed in the tribe Delesserieae. Our morphological observations on Apoglossum and the ‘Delesseria’ species belonging to the resurrected genus Paraglossum from the Southern Hemisphere show that they possess a distinct procarp. Apoglossum has two one‐celled sterile groups that divide after fertilization and Paraglossum consists of two one‐celled sterile groups that do not divide after fertilization, but in which the nuclei divide to produce four to eight nuclei in the undivided sterile groups. In contrast, the procarp in D. sanguinea, the type species of the tribe Delesserieae, consists of two 2–6‐celled sterile groups before fertilization and the number of sterile cells double after fertilization. The development of the carposporophyte in both Apoglossum and Paraglossum is shown to be unique in the subfamily Delesserioideae. The pit connections between the segments of the gonimoblast filaments broaden without fusion and secondary carposporangia are produced. This pattern is absent in other members of the Delesserioideae, but has been reported for the tribes Myriogrammeae and Schizoserideae in the new subfamily Phycodryoideae Lin, Fredericq et Hommersand. Based on both LSU rDNA and rbcL sequence analyses, the Delesserieae is restricted to species of Delesseria and Membranoptera from the North Atlantic and North Pacific Oceans. In contrast, the species of Apoglossum and Paraglossum form a distinct cluster having a center of distribution in the Southern Hemisphere with only a few species, such as A. ruscifolium, reaching the Northern Hemisphere. In this study, details of postfertilization development leading to the cystocarp are illustrated for the type species of Apoglossum and Paraglossum and a new tribe, the Apoglosseae, is recognized in the Delesseriaceae.
The Roots of Land Plants: Recent Research on Early Diverging Lineages in the Evolution of Higher Drier Algae
Authors: McCourt R. M. , Karol K. G. , Delwiche C. F.
Published: March 2003

Recent multigene phylogenetic analyses of charophycean algae sensu Mattox and Stewart have advanced our understanding of the relationships of the green algae that are most closely related to land plants. Several clades of green algae are monophyletic with land plants (i.e. liverworts, mosses, nonvascular and vascular plants that arose from an aquatic ancestor) to the exclusion of other green algae: Mesostigma (a flagellate unicell); the Chlorokybales (small packets of cells); Klebsormidiales (unbranched filaments); Zygnematales (conjugating unicells, filaments, and colonies); Coleochaetales (filamentous and parenchymatous thalli); and Charales (branched filamentous thalli with complex nodal structure). The morphological and molecular diversity of the extant members of this nearly exclusively freshwater clade is remarkable. Moreover, the taxon diversity within clades is highly asymmetric, having yielded several distinctive albeit small groups of green algae, as well as one of the major evolutionary success stories on earth, viz. land plants. The most recent analysis (Karol et al. (2001) Science 294 : 2351–2353) of four genes from plastid, mitochondrial, and nuclear compartments strongly support the sister relationships of Charales (stoneworts) to the most primitive land plants. The analysis also shows that within this clade there has been a trend toward increasing complexity of thallus form (from unicells, to filaments, to branching and parenchymatous thalli) and reproduction (absence of sexual reproduction to iso‐ or anisogamy, to oogamy). Although the major clades mentioned above are well supported by molecular analyses, relationships among these groups are less well‐resolved, especially for the Klebsormidiales, Chlorokybales, and Mesostigma. This paper reviews the morphological and molecular evidence for the relationships among and within these groups. More sequence data from a broader sampling of taxa at the base of the charophyceans (including perhaps some algae not now known to be charophytes) should provide a clearer picture of the evolution of this group and the reasons for its success.
Characterization of sufB Sequences from Nongreen Photoautotrophs
Authors: Misner I. J. , Bailey J. C. , Freshwater D. W.
Published: March 2003

Partial sequences for the hypothetical chloroplast frame 24 (ycf24) were determined for 13 species of algae representing the classes Bacillariophyceae, Chrysophyceae, Pelagophyceae, Pinguiophyceae, Prymnesiophyceae, Raphidophyceae, and Xanthophyceae. In many databases ycf24 is considered an ATP‐binding cassette (ABC) transporter. Our analyses of translated amino acid sequences demonstrate that these sequences lack Walker A and B boxes, a conserved ABC signature sequence motif, and transmembrane domains that characterize ABC transporters. Our data, as well as those of others, convincingly indicate that ycf24 is not an ABC transporter and is instead homologous to the sufB gene first described from prokaryotes. The function of the sufB gene product in eukaryotic plastids is not known with certainty but it likely plays a key role in iron–sulfur (2Fe−2S) cluster formation. Our data, unpublished results and database searches imply that sufB is plastid encoded in the ‘red’ plastid lineage, but has been transferred to the nucleus or lost within the streptophyte lineage. Phylogenetic analyses of all available eucaryotic sufB sequences indicate that this gene is a useful marker for tracing the ancestry of plastids and their hosts. For example, our sufB analyses indicate that the 35‐Kb circular plastid genome of Plasmodium falciparum is a member of the ‘red’, not ‘green’, plastid lineage and was acquired via secondary endosymbiosis. Our results also support the hypothesis that, despite their similarities, the plastids of prymnesiophytes and heterokont algae were independently obtained by separate secondary endosymbiotic events.
Characterization of Macroalgal Epiphytes on Thalassia Testudinum in Tampa Bay, Florida
Authors: Cho T. O. , Fredericq S. , Yates K. K.
Published: March 2003

Blooms of seagrass epiphytes have potentially important economic and ecological consequences in Tampa Bay, one of the Gulf of Mexico's largest estuaries. As part of a Tampa Bay pilot study to monitor the impact of environmental stresses, precise characterization of epiphyte diversity is required for efficient management of affected resources, and thus may be used as a rational basis for assessment of ecosystem health. Fixed monitoring sites were selected north of Port Manatee, composed of dense and sparse Thalassia testudinum seagrass sites. A total of 13 epiphytic species encompassing green, brown and red macroalgae were manually collected in May 2001 from dense seagrass beds versus nine species from sparse beds. Epiphytes only collected in the dense beds were Enteromorpha flexuosa, Sphacelaria rigidula, Ceramium byssoideum, and Herposiphonia tenella; epiphytes only occurring in the sparse beds were Griffithsia and Stylonema alsidii. A correlation seems to emerge among attachment mode of epiphyte to host, presence of cortication and epiphyte length. A main goal of this ongoing study is the determination of indicator species for both healthy and stressed seagrass bed environments using both taxonomic and gene‐sequencing techniques.
Sleep Apnea, Delirium, Depressed Mood, Cognition, and ADL Ability After Stroke
Authors: Sandberg Olov , Franklin Karl A. , Bucht Gösta , Gustafson Yngve
Published: March 2003

OBJECTIVES: The incidence of sleep apnea and stroke increases with age. The aim of this study was to investigate the presence of sleep apnea after stroke and its relationship to delirium, depressed mood, cognitive functioning, ability to perform activities of daily living (ADLs), and psychiatric and behavior symptoms.

DESIGN: Cross‐sectional study.

SETTING: Geriatric stroke rehabilitation unit.

PARTICIPANTS: 133 patients (78 women and 55 men, mean age 77.1 ± 7.7 years) consecutively admitted to a geriatric stroke rehabilitation unit.

MEASUREMENTS: All patients underwent overnight respiratory sleep recordings at 23 ± 7 days (range 11 to 41 days) after suffering a stroke. The patients were assessed using the Organic Brain Syndrome Scale, Montgomery‐Åsberg‐Depression‐Rating Scale, Mini‐Mental State Examination (MMSE), and Barthel‐ADL Index. Sleep apnea was defined as an apnea‐hypopnea index (AHI) of 10 or more.

RESULTS: The median of the AHI for the studied sample (N = 133) was 13 (range 0–79; interquartile range 6–28). Fifty‐nine percent fulfilled the criteria for sleep apnea; 52% with first‐ever stroke had sleep apnea. More patients with sleep apnea than without were delirious, depressed, or more ADL‐dependent. Sleep apnea patients also had a higher frequency of ischemic heart disease and had more often suffered from an earlier cerebral infarction. Multivariate analysis showed that obesity, low ADL scores, ischemic heart disease, and depressed mood were independently associated with sleep apnea. Low ADL scores, apnea‐related hypoxemia, body mass index ≤27, and impaired vision were independently associated with delirium. The presence of sleep apnea was not associated with any specific type of stroke or location of the brain lesion.

CONCLUSIONS: Sleep apnea is common in stroke patients and is associated with delirium, depressed mood, latency in reaction and in response to verbal stimuli, and impaired ADL ability. We suggest a trial investigating whether delirium, depressed mood, and ADL ability improve with nasal continuous positive airway pressure treatment of sleep apnea in stroke patients.
Laparoscopic Surgery in Older Adults
Authors: Efron David T. , Bender Jeffrey S.
Published: March 2003

This article provides an overview of the current role of laparoscopic surgery in older patients. A retrospective review and analysis of the recent English‐language literature on laparoscopic procedures with special attention devoted to those articles focused on geriatric patients was performed. Laparoscopic surgery has rapidly become the fastest‐growing discipline within the surgical arena and new applications for laparoscopy continue to be reported. The primary benefits to patients of these developments are smaller scars, decreased postoperative pain, and more‐rapid return to normal activity. As society ages, more older patients will present with pathology amenable to laparoscopic intervention. Several aspects of laparoscopy impose unique physiologic stresses and, as such, may alter surgical risk to the geriatric patient. In addition, older patients often have delayed surgical interventions because of more‐conservative medical management or unusual symptomatology, which may further complicate the laparoscopic approach. These limitations may alter the risk‐to‐benefit ratio of laparoscopic versus open procedures. Despite this lack of elucidation of full‐risk profiles, laparoscopic approaches should be considered regardless of a patient's age.
Weight Change in Old Age and its Association with Mortality
Authors: Newman Anne B. , Yanez David , Harris Tamara , Duxbury Andrew , Enright Paul L. , Fried Linda P. ,   for the Cardiovascular Study Research Group
Published: March 2003

OBJECTIVES:

Previous studies of weight change and mortality in older adults have relied on self‐reported weight loss, have not evaluated weight gain, or have had limited information on health status. Our objective was to determine whether 5% weight gain or loss in 3 years was predictive of mortality in a large sample of older adults.

DESIGN:

Longitudinal observational cohort study.

SETTING:

Four U.S. communities.

PARTICIPANTS:

Four thousand seven hundred fourteen community‐dwelling older adults, age 65 and older.

MEASUREMENTS:

Weight gain or loss of 5% in a 3‐year period was examined in relationship to baseline health status and interim health events. Risk for subsequent mortality was estimated in those with weight loss or weight gain compared with the group whose weight was stable.

RESULTS:

Weight changes occurred in 34.6% of women and 27.3% of men, with weight loss being more frequent than gain. Weight loss was associated with older age, black race, higher weight, lower waist circumference, current smoking, stroke, any hospitalization, death of a spouse, activities of daily living disability, lower grip strength, and slower gait speed. Weight loss but not weight gain of 5% or more was associated with an increased risk of mortality that persisted after multivariate adjustment (Hazard ratio (HR) = 1.67, 95% CI = 1.29–2.15) and was similar in those with no serious illness in the period of weight change. Those with weight loss and low baseline weight had the highest crude mortality rate, although the HR for weight loss was similar for all tertiles of baseline weight and for those with or without a special diet, compared with those whose weight was stable.

CONCLUSIONS:

This study confirms that even modest decline in body weight is an important and independent marker of risk of mortality in older adults. J Am Geriatr Soc 49:1309–1318, 2001.
Apathy in Alzheimer's Disease
Authors: Landes Allan M. , Sperry Susan D. , Strauss Milton E. , Geldmacher David S.
Published: March 2003

Apathy, or loss of motivation, is arguably the most common change in behavior in Alzheimer's disease (AD) but is underrecognized. Apathy represents a form of executive cognitive dysfunction. Patients with apathy suffer from decreased daily function and specific cognitive deficits and rely on families to provide more care, which results in increased stress for families. Apathy is one of the primary syndromes associated with frontal and subcortical pathology, and apathy in AD appears to have multiple neuroanatomical correlates that implicate components of frontal subcortical networks. Despite the profound effects of this common syndrome, only a few instruments have been designed to specifically assess apathy, and these instruments have not been directly compared. Assessment of apathy in AD requires clinicians to distinguish loss of motivation from loss of ability due to cognitive decline. Although apathy may be misdiagnosed as depression because of an overlap in symptoms, current research has shown apathy to be a discrete syndrome. Distinguishing apathy from depression has important treatment implications, because these disorders respond to different interventions. Further research is required to clarify the specific neuroanatomical and neuropsychological correlates of apathy and to determine how correct diagnosis and treatment of apathy may improve patient functioning and ease caregiver burden.
Highlights of Papers in Clinical Investigations Section: Vascular Risk and Cognitive Impairment in an Older, British, African‐Caribbean Population
Authors: Steward R , Richards M , Brayne C
Published: March 2003

In this study, 278 adults age 55 to 75 who were born in a Caribbean nation were interviewed and examined for cardiovascular risk factors and their association with cognitive impairment. Marked differences were found between groups with low and normal/high levels of education in the strength of associations between measures of vascular risk and cognitive impairment. However, physical activity was negatively associated with cognitive impairment. Physical exercise may be an important public health strategy in reducing the burden of cognitive impairment.