bluuebunny/crossref_metadata_2025 huggingface dataset:
RELATIONSHIP BETWEEN PERIODIC RESUSPENSION EVENTS AND PHYTO‐PLANKTON BLOOMS IN LAKE MICHIGAN
Authors: Julius M. L. , Goad L.
Published: November 2003

Lake Michigan provides an ideal location for comparing episodic physical forcing effects (storm events) on phytoplankton processes and the more persistent seasonal variability of phytoplankton communities. This is because of the duration and extent of the highly turbid, recurrent coastal plume (RCP) in the lake during the winter/early spring. Although the RCP coincides with the initiation of the basin wide spring diatom bloom, linkages between the duration and intensity of the plume and the prominent role of light availability in regulating Lake Michigan phytoplankton growth during the spring isothermal period have been postulated, but not verified. As such the concurrent physical and biological events provide a novel opportunity to examine how variations in biological rate processes, coupled with transport and resuspension phenomena associated with the RCP, affect the distributions of organisms, evolution of communities, and growth and primary production of Lake Michigan phytoplankton. In this study, phytoplankton assemblages from pre, post, and active plume events are examined from three stations in Lake Michigan. Species assemblages include chlorophytes, chrysophytes, and diatoms. The diatom flora was particularly abundant. Species composition changed rapidly during storm events, with resting cell forming taxa playing a significant role in these modifications. Ephemeral species appeared during the circulation event and decreased once storm activity subsided. Other taxa were able to establish themselves in the phytoplankton community during the plume events and persisted after storm activity subsided. Understanding activity during these circulation events will lead to a better understanding of overall community structure development throughout the year.
PATTERNS OF RECRUITMENT AND DISTRIBUTION OF ULVA AND ENTEROMORPHA POPULATIONS IN A KOREAN INTERTIDAL SHORE
Authors: Kim J.H. , Park S.R.
Published: November 2003

Patterns of recruitment and abundance of Ulva pertusa and Enteromorpha linza in the three locations on the south coast of Korea where green tide frequently occurred were investigated with respect to the substrate profile, temporal and spatial variations, and their persistence. Artificial substrates (10 to 20 cm) were made of a mixture of a piece of granite rock and cement on ceramic tiles. These setting plates, representing different surface texture, were placed horizontally and vertically along the rocky shoreline, and replaced every 1 to 2 months. Both populations showed highly seasonal blooms, with peaks in October, 1998 to February, 1999 and another slight peak was observed in the fall of 1999 only for Ulva. However, the winter peak of 1998 did not appeared in the following year, indicating that a significant year‐to‐year variation existed. Regarding their settlement onto artificial plates with different roughness, Ulva preferred to settle on the rough surface both in the upper and lower intertidal zone; however, this pattern only appeared in the upper zone for Enteromorpha. Vertical distribution of the two populations was well separated; Enteromorpha was more abundant in the upper zone and Ulva in the lower zone. Their seasonal blooms were concomitant with ammonia levels, but occurrence was not well correlated with nitrate and phosphate. The ability of the populations to persist, once blooms occurred, was also distinct; Ulva persisted ca. twice as long as Enteromorpha, having a greater impact in the presence of green tide in this geographical area.
MEASUREMENT OF MICROALGAL CELL VOLUME BY FLOW CYTOMETRY
Authors: Leighfield T.A. , Van Dolah F.M.
Published: November 2003

Single cell analysis by flow cytometry is a powerful tool that has been employed to identify many different characteristics of phytoplankton populations. Cell volume is an important physiological component of many cellular processes. We have used a Coulter EPICS XL flow cytometer to measure cell volume in the spheroid dinoflagellate Amphidinium operculatum as a function of forward scatter. Cell volume measurements of this alga were quantified as equivalent spherical diameters from a standard curve obtained with latex beads of known diameter. This parameter was used to monitor cell diameter throughout the cell division cycle. In log phase cultures, A. operculatum showed increasing cell volumes throughout the light phase and a maximum cell volume concurrent with the onset of cell division late in the light phase. The maximum equivalent spherical diameter measured 14 μm, while the minimum equivalent spherical diameter was 10 μm that occurred late in the dark phase. Stationary phase cultures of A. operculatum did not exhibit oscillating cell volumes throughout the diel cycle. Chemical inhibition of the cell cycle using 100 μM olomoucine diminished cell volume changes during the light phase. These results suggest a coupling of size control to the cell division cycle.
PHENOLOGY OF PORPHYRA PENDULA (BANGIALES; RHODOPHYTA) IN THE SOUTHWESTERN GULF OF CALIFORNIA, MEXICO
Authors: López‐Vivas J. M. , Riosmena‐Rodriguez R.
Published: November 2003

Porphyra pendula Dawson is an endemic species of the mid‐intertidial zone in the Gulf of California. Based on surveys from the Phycological Herbarium of UABCS since 1994, we found an extensive population of this species in Punta Coyote, south of La Paz. Here, we assess the phenology of the gametophyte phase from December of 1998 to June of 1999 with visits every 2 weeks. Our results show significant temporal and spatial changes in length and width of the plant, with some quadrants displaying two peaks in development ( January and March) and other quadrants with a peak only in January. A significant correlation existed between length and width of the blade and is linked with plant maturation, observations which strongly support the isometric growth rate of the species. No differences between exposed and protected areas were observed suggesting stronger differences between quadrants. Differences plants in length and in color existed between male and female plants; the males were smaller and yellow and females/carposporophyte were larger and red‐purple. Most of the thalli were reproducing during the study, with a greater proportion of females than males (ca. 2:1). Our results suggest that the morphological changes in this species may be related with temperature and day length.
PHYLOGENY OF THE GENUS CHLOROCOCCUM: A STUDY OF 18S AND 26S rRNA GENE SEQUENCES
Authors: Michalopulos J.U. , Buchheim J.A. , Buchheim
Published: November 2003

Phylogenetic studies of 18S rRNA gene sequence data support an alliance of the green algal genus, Chlorococcum, with other chlamydomonadalean taxa that produce walled, motile stages. Moreover, these phylogenetic studies indicate that Chlorococcum is not monophyletic, but rather falls into two distinct lineages. However, these molecular phylogenetic studies were based on only a few taxa in a genus that exhibits marked habitat diversity. In particular, numerous species of Chlorococcum currently in the UTEX collection have been isolated from naturally acidic environments. Except for a few groups (e.g., desmids), acidic environments are not generally regarded as niches for widespread exploitation by green algae. A new investigation of diversity among species of Chlorococcum included broader taxon and data sampling schemes. Sequence data from both the nuclear‐encoded 18S and 26S rRNA genes were collected from 17 different UTEX and SAG isolates of Chlorococcum. In addition, controlled growth experiments at varying acidity (pH 5.0, 6.0, and 8.0) were conducted. Results of these investigations suggest that the Chlorococcum‐like morphology has evolved in at least three lineages. Furthermore, these data suggest that the ability to grow optimally at low pH has independently evolved in several lineages.
GLOBAL SYSTEMATIC AND PHYLOGENETIC ANALYSIS OF SARGASSUM IN THE GULF OF MEXICO, CARIBBEAN AND PACIFIC BASIN
Authors: Phillips N. , Smith C. , Morden C. , Fredericq S.
Published: November 2003

Sargassum is one of the most species‐rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific‐Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL‐IGS‐rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL‐IGS‐rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well‐resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events.
EVOLUTION OF BIOLUMINESCENCE IN MARINE DINOFLAGELLATES
Authors: Robertson D. L. , Hastings J.W.
Published: November 2003

Bioluminescence is broadly distributed in marine dinoflagellates and has been intensively studied in Lingulodinium (Gonyaulax) polyedra. In this species, bioluminescence is regulated in a circadian fashion; the enzyme (luciferase) and the luciferin (substrate)‐binding protein are synthesized and degraded on a daily basis. Synthesis of both proteins is regulated at the level of translation. The L. polyedra luciferase gene is composed of three contiguous domains that are greater than 75% identical at the nucleic acid level. Possible explanations for the high degree of sequence conservation include: (1) the domains evolved through a recent duplication event; (2) the sequence similarity is maintained by a molecular process such as gene conversion; or (3) there is a functional role associated with the primary nucleic acid sequence, such as in the translational regulation of luciferase expression. The phylogenetic relationship of dinoflagellates predicted from 18S rDNA genes provides a framework for examining the molecular evolution of the regulation of luciferase expression and of genes encoding luciferase and the luciferin‐binding protein. In particular, we are examining the evolution of the circadian rhythm of bioluminescence and of luciferase abundance, the presence/absence of the luciferin‐binding protein, and the molecular structure of the luciferase gene. We anticipate that this approach will distinguish between regions of the luciferase molecule that are conserved for enzyme function versus those concerned with the regulation of protein expression. In addition, it will provide insight into the evolution of the regulatory processes and pathways.
PREDAEA LUCESCENS SP. NOV., A NEW COOL‐TEMPERATE AUSTRALIAN SPECIES WITH UNIQUE, UNDIFFERENTIATED NUTRITIVE FILAMENTS
Authors: Saunders G.W. , Kraft G.T.
Published: November 2003

The red algal genus Predaea (Schizymeniaceae, Gigartinales) includes approximately a dozen species of tropical and subtropical distribution. Plants are gelatinous in consistency, and the carpogonial branches and auxiliary cells are widely separated in female gametophytes (non‐procarpy). Predaea is distinguished from other red algal genera in possessing clusters of small rounded nutritive cells that are borne on the one proximal and distal two cells directly attached to the auxiliary cell. We describe a new species from cool‐temperate (10–18° C yearly range) southeastern Australia that, unlike the tropical and subtropical species, lacks the typical gelatinous texture and has dwarf vegetative filaments of normally contoured cells associated with the auxiliary cell rather than small clusters of spherical nutritive cells. Anatomical and molecular data are combined to postulate the phylogenetic affinities of the new species to others of the genus, to highlight relationships of Predaea to other genera of the Schizymeniaceae, and to consider this family relative to others now placed in the Gigartinales.
GEOGRAPHICAL CORRELATION OF MORPHOLOGICAL VARIATION IN SILVETIA COMPRESSA (FUCACEAE, FUCALES, PHAEOPHYCEAE)
Authors: Silva P.C. , Pedroche F.F. , Chacana M.E. , Aguilar Rosas L.E. , Aguilar Rosas L.E.
Published: November 2003

Silvetia compressa ( J. Agardh) Serrão et al. is a common member of the upper intertidal fucoid community on the Pacific coast of America from Humboldt County, California, to Punta Baja, Baja California, Mexico. A relatively narrow range of morphological variability is exhibited by most mainland populations, regardless of latitude, but some mainland populations and all insular populations participate in a complex pattern that we have attempted to analyze. A few populations on the Monterey Peninsula in which the fronds are atypically delicate were described by Setchell & Gardner as f. gracilis, to which was assigned a population from Santa Catalina Island. After comparing populations from various parts of the range of the species, including all of the Channel Islands, we conclude that two subspecies may be recognized. In subsp. compressa, which includes f. gracilis as a growth form and occurs chiefly on the mainland, the frond is robust with long tapered receptacles. In the variant subspecies, which is chiefly insular but also occurs on the coast of northern Baja California, the typical frond has slender axes as in f. gracilis, but is more densely branched and has short ellipsoidal receptacles. Comparison of nucleotide sequences from the ITS regions of rDNA revealed an identical pattern for subsp. compressa from Baja California and central California, including populations assignable to f. gracilis. By contrast, the pattern for the variant subspecies differed by 2 bp (0.3%) from that of subsp. compressa.
SYMBIOTIC ORIGIN OF A NOVEL ACTIN GENE IN THE CRYPTOPHYTE, PYRENOMONAS HELGOLANDII
Authors: Stibitz T.B. , Keeling P.J. , Bhattacharya D.
Published: November 2003

Cryptophytes are photosynthetic protists that have acquired their plastids through the secondary symbiotic uptake of a red alga. A remarkable feature of cryptophytes is that they maintain a reduced form of the red algal nucleus, the nucleomorph, between the second and third plastid membranes (periplastidial compartment, PC). The nucleomorph is thought to be a transition state in the evolution of secondary plastids with this genome ultimately being lost (e.g., as in heterokonts, haptophytes, euglenophytes) when photosynthesis comes under full control of the “host” nucleus. For this to happen, all genes for plastid function must be transferred from the nucleomorph to the nucleus. In this regard, it is generally assumed that nucleomorph genes with functions unrelated to plastid or PC maintenance are lost. Surprisingly, we show here the existence of a novel type of actin gene in the host nucleus of the cryptophyte, Pyrenomonas helgolandii, that has originated from the nucleomorph genome of the symbiont. Our results demonstrate for the first time that secondary symbionts can contribute genes to the host lineage that are unrelated to plastid function. These genes are akin to the products of gene duplication and provide a source of evolutionary novelty that could significantly increase the genetic diversity of the host lineage. We postulate that this may be a common phenomenon in algae containing secondary plastids that has yet to be fully appreciated due to a dearth of evolutionary studies of nuclear genes in these taxa.
SURVEY OF BENTHIC DIATOM COMMUNITIES FROM LOTIC SYSTEMS WITHIN THE WESTERN ALLEGHENY PLATEAU
Authors: Verb R. G. , Vis M. L.
Published: November 2003

Over the course of 3 years (1997–1999), 72 stream sites were sampled for epilithic diatom communities. The analysis of these samples has led to the identification of over 325 species of diatoms. In addition to sampling the diatom community, selected physical and chemical parameters were recorded from each stream reach. These parameters included pH, specific conductance, current velocity, SRP, nitrate, silica, and total alkalinity. Canonical Correspondence Analysis (CCA) was used to identify influential environmental parameters and to assess the response of the diatom community to prominent anthropogenic inputs in the region (i.e. coal mine drainage, eutrophication). The initial analyses indicate that pH was the most influential environmental parameter along the first CCA axis. This shift was not unexpected, as acid mine drainage (AMD) in the region leads to a wide range of pH values (2.8–7.93). The highly acidic sites were characterized by species of the genus Eunotia (specifically E. exigua and E. steineckei), Frustulia rhomboides, and Pinnularia subcapitata. Furthermore, Achnanthidium minutissimum was the most widely distributed of the diatom species encountered, being found at 94% of the sites sampled. Streams that fluctuated between acidic and circumneutral pH (termed “teeter‐totter”) had greater abundances of Brachysira vitrea than other streams in this survey. Further implications for the use of these diatom communities as biomonitoring tools and the distribution of assemblages within the Western Allegheny Plateau will be discussed.
ANABAENA AND MICROCYSTIS IN THE PACIFIC NORTHWEST: A TALE OF PLASTICITY
Authors: Williams C.R. , Peters B. , Waaland J.R.
Published: November 2003

The molecular marker, cpcBA‐IGS, was used to examine the biogeography of representatives of Anabaena and Microcystis collected from Pacific Northwest lakes and their phylogenetic relationship to isolates from the UTEX and CCAP culture collections. cpcBA‐IGS contains portions of the alpha and beta subunit of cyanophycocyanin with an intergenic spacer (IGS) of ∼100 base pairs situated between the subunits. The use of this cyanobacteria specific marker and primers allowed us to amplify cpcBA‐IGS DNA from uni‐cyanobacterial field samples. The morphology and habit of specimens were documented by photomicroscopy. Single filaments or colonies of field material and 3–4 filaments of culture material were then amplified using the polymerase chain reaction (PCR). Results include analysis of non‐toxic summer and toxic winter blooms of Anabaena from 1989–1997 in American Lake, WA and a comparison of non‐toxic and toxic Microcystis from Lake Sammamish, WA. A preliminary phylogenetics analysis of Pacific Northwest and UTEX isolates also was performed using parsimony, maximum likelihood and distance methods. The results of this analysis suggest that revision of Anabaena and Microcystis taxonomy may be needed.
THE EFFECT OF NITROGEN SOURCE ON THE GROWTH AND TOXICITY OF THREE POTENTIALLY HARMFUL DINOFLAGELLATES
Authors: Burns C. L. , Pennock J.R. , Lores E. M. , Greene R. M.
Published: November 2003

Increases in population and agriculture in coastal areas can result in increased nutrient inputs and alterations in the ratios of organic to inorganic nutrients in coastal waters. Such changes in coastal nutrient regimes can affect phytoplankton community structure by creating conditions favorable for growth and dominance of algae that were not dominant before. The effect that changes in ratios and concentrations of nutrients have on toxicity of harmful algal species is not well known. There seems to be a relationship; however, between nutrient stress and toxin production among harmful phytoplankton producing low‐N toxins, e.g. Diarrhetic Shellfish Poisoning (DSP) toxins. Even less is known about the relationship between organic nutrient uptake and toxin production. Benthic species and species in coastal areas are probably exposed to greater fluxes of dissolved organic nitrogen (DON). In this study, benthic and planktonic species of Prorocentrum were grown on L1 media with the sole N‐source varying among treatments as nitrate, ammonium, urea, L‐glutamic acid, and high molecular weight natural DON. An ELISA specific to the DSP toxins, okadaic acid and 35‐methylokadaic acid, was used to determine toxin production by each species when grown on the different N sources. Preliminary results indicate that some organic forms of N support growth as well as inorganic forms for Prorocentrum minimum, P. mexicanum, and P. hoffmannianum.
EFFECT OF TEMPERATURE AND DESICCATION ON THE PHOTOSYNTHETIC PERFORMANCE OF PORPHYRA PERFORATA
Authors: Cabello‐Pasini A. , Diaz‐Martín  , Muñiz‐Salazar R. , Zertuche‐Gonzalez J.A. , Pacheco‐Ruiz I.
Published: November 2003

Porphyra perforata is a common seaweed inhabiting the upper intertidal zone, and as a consequence it experiences great fluctuations in tissue temperature and desiccation. The objective of this work was to evaluate the effect of ambient temperature and the tissue desiccation status on the photosynthetic performance of P. perforata. Photosynthetic performance was evaluated polarographically after the temperature or desiccation treatments. Maximum photosynthesis (Pmax) occurred between 25 and 30° C and decreased at higher and lower temperatures, however, no significant differences were observed in the initial slope of photosynthesis (α) from 10 to 30° C. This suggests that the photosynthetic efficiency of this species does not decrease as a result of fluctuating temperatures during tidal emergence/submergence. Pmax and α were relatively constant in tissue of P. perforata with 5 to 100% relative water content. This also suggests that natural desiccation rates during low tides do not decrease photosynthetic rates in this species. Variations in the synthesis of specific proteins as a result of fluctuations in temperature and relative water content in the tissue of P. perforata are being studied.
PHOTOSYNTHESIS IN THE DEEP BLUE SEA: PHOTOPHYSIOLOGICAL RESPONSES OF PHAEODACTYLUM TRICORNUTUM TO DYNAMIC AND STATIC IRRADIANCES
Authors: Evens T.J. , Chapman D.J.
Published: November 2003

The kinetics of xanthophyll‐cycle pigment switching and fluorescence quenching dynamics in the marine diatom, Phaeodactylum tricornutum were determined in the context of dynamic and static growth light. Cultures were grown in a modified photobioreactor capable of producing dynamic light fields which exhibited attenuation characteristics similar to that of water; these cultures were pre‐acclimated to high and low, static and dynamic, growth‐light regimes for at least three days, and then examined under high, static and dynamic light. Pigment pools varied markedly. The two static light cultures had pigment complements that were very similar to “traditional” high and low‐light static cultures. The dynamic‐light grown cultures had pigment complements, which were very similar to each other but different from the static‐grown cultures. The maximum xanthophyll‐cycle pigment de‐epoxidation state attainable under saturating light was equal for all four treatments. Induction of fluorescence quenching was significantly faster in the static‐grown cultures, while xanthophyll‐cycle de‐epoxidation rates did not show as much variation. Minimum irradiances for xanthophyll‐cycle induction were correlated to average growth irradiance. Taken as a whole, the results from this work suggest that dynamic light‐grown phytoplankton have a unique photosynthetic functionality that is different from static light‐grown phytoplankton. The significance of these observations in the context of realistic light fields, and the photosynthetic response capabilities of algae grown under them will be discussed.
HETEROGENEITY OF CHLOROPLAST GAPDH GENES IN THE DINOPHYCEAE
Authors: Fagan T.F. , Hastings J.W.
Published: November 2003

Dinoflagellates provide valuable models for studying endosymbiosis and chloroplast evolution. While many species are heterotrophic, photosynthetic species containing plastids of different evolutionary origin have been isolated, indicating that dinoflagellates acquired chloroplasts multiple times during evolution. Furthermore, dinoflagellates contain nuclear genes encoding chloroplast proteins that are not typically found in eukaryotes. These include the type II form of RuBisCO, and a eubacterial form of glyceraldehyde‐3‐phosphate dehydrogenase (GAPCp) that we have recently characterized from Gonyaulax polyedra. The evolutionary origin of this GAPCp isoform is unclear. It is phylogenetically distant from the Gonyaulax cytosolic form (GAPC) and from the chloroplast forms (GAPA/B) of cyanobacterial origin typically found in photosynthetic eukaryotes. It has previously been described only from cryptomonads, raising the possibility that Gonyaulax acquired the gene through lateral transfer. We have addressed this issue by examining the phylogeny of GAPDH genes from other dinoflagellates. We have isolated genes from Gymnodinium mikimotoi and Pyrocystis lunula. The predicted protein sequence of the G. mikimotoi gene is 47% similar to Gonyaulax GAPC and GAPCp and phylogenetic analysis places them in the same eubacterial clade. The predicted amino acid sequence of the P. lunula gene is 41% and 37% similar to Gonyaulax GAPCp and GAPC isoforms, respectively. However, phylogenetic analysis groups it within the clade comprising cyanobacterial and eukaryotic GAPA/B isoforms and shows that it is closely related to the chloroplast form of Euglena gracilis. Thus, within the Dinophyceae, GAPDH genes of different evolutionary origin have been recruited to participate in chloroplast metabolism.
EXTRACELLULAR MATRIX PROTEO‐GLYCANS INVOLVED IN DIATOM ADHESION AND MOTILITY
Authors: Gretz M.R.
Published: November 2003

Although diatom extracellular matricies are usually thought of exclusively in terms of the beautiful, architecturally complex silicious frustule, polymers exuded through the frustule are critical mediators of interactions with the external environment. In several species, complex proteoglycans appear to be the primary components involved in adhesion and motility. When viewed with high‐resolution cryo‐scanning electron microscopy methods, the ubiquity and pervasiveness of these polymers was revealed in both freshwater and marine taxa. Monoclonal antibody mapping of carbohydrate epitopes characterized by NMR, methylation and monosaccharide analysis and correlated with structural observations by EM revealed an organizational pattern far more complex than previously proposed. Modeling assembly of extracellular “stalks” in the marine biofouling diatom Achnanthes longipes involves intracellular sequestering of multiple components, deposition at the protoplasmic membrane/diatotepum interface, transport through the multilayered diatotepum and holes in the silica, extrusion from the frustule, and assembly into a very complex multi‐laminate biocomposite structure. The mechanism of extracellular polymer participation in motility is complex in a different way, as some current models of raphe associated motility involve cytoskeletal interactions and molecular motors.
EXPERIMENTAL STUDY OF PHYTOPLANKTON SPECIES COMPOSITION, ALTERNATE STATES, AND COMMUNITY BREAKPOINTS ALONG A PHOSPHORUS GRADIENT
Authors: Holz J.C. , Hoagland K.D. , Joern A.
Published: November 2003

A model combining algal mortality due to selective zooplankton grazing with the Monod model of phytoplankton growth was used to predict phytoplankton species composition along a gradient of phosphorus (P) concentration and zooplankton grazing pressure. Model predictions were compared to the results of a mesocosm experiment of phytoplankton species composition along a range of P concentrations of five to 115 μg L−1 and potential grazing loss rates of 0.001 to 0.27 day−1. The effect of the P gradient was measured by monitoring phytoplankton and zooplankton species composition and biomass, and physical and chemical parameters for seven weeks in 12 fiberglass tanks (5500 L) filled with lake water and associated plankton. P concentrations were manipulated so that tanks were evenly distributed along the gradient. Using laboratory derived Monod growth constants for P and literature values of phytoplankton selectivity coefficients, zooplankton filtering rates, and zooplankton assimilation efficiencies, the model correctly predicted (1) the existence of alternate community states, (2) breakpoints between the alternate states which are similar to the P concentrations defining Vollenweider's lake trophic states, and (3) phytoplankton species composition along the P gradient in the mesocosm study. These results suggest that the trade‐off between competitive ability for P and edibility is a primary factor structuring phytoplankton communities, and that multiple states exist which may be consistent with the long‐standing P‐based lake trophic classification.
Synergy of Passive Coating and Targeted Drug Delivery:
Authors: BARTORELLI ANTONIO L. , TRABATTONI DANIELA , FABBIOCCHI FRANCO , MONTORSI PIERO , MARTINI STEFANO DE , CALLIGARIS GIUSEPPE , TERUZZI GIOVANNI , GALLI STEFANO , RAVAGNANI PAOLO
Published: November 2003

Stents represent a major step forward in the treatment of coronary artery disease since the introduction of balloon angioplasty. They have demonstrated the reduction of angiographic indexes of restenosis and rates of repeat revascularization. However, in‐stent neointimal proliferation represents the persisting limitation and challenge. Local delivery using a stent platform for deposition of therapeutic drug concentration in the arterial wall has emerged as an effective strategy to reduce in‐stent neointimal hyperplasia and restenosis. The purpose of this article is to describe the design characteristics of a new drug‐eluting stent. Its unique features consist of integral Carbofilm™ thromboresistant coating combined with the capability to load the drug into and to release it from deep sculptures made on the external surface of the stent. The advantages of this design are the possibility to load higher amounts of drug, to selectively deliver it to the vessel wall without loss in the blood stream, and to improve the biocompatibility and thromboresistance of the stent. Preclinical studies, using tacrolimus as the biological agent, showed excellent vessel tissue response and mild inflammation scores. A significant reduction of intimal proliferation was observed in comparison with a control stent. The enrollment in a safety first‐in‐man evaluation has been successfully completed. A randomized, double‐blind, multicenter study is expected to start at the completion of the “safety” evaluation. (J Interven Cardiol 2003;16:499–505)
Percutaneous Implantation of Aortic Valve Prosthesis in Patients with Calcific Aortic Stenosis:
Authors: ELTCHANINOFF HÉLÈNE , TRON CHRISTOPHE , CRIBIER ALAIN
Published: November 2003

In April 2002, after extensive ex‐vivo and animal implantation studies, we performed the first successful implantation of a new percutaneous aortic valve in a patient with endstage aortic stenosis. The purpose of this article is to give a detailed description of the technique of percutaneous implantation of aortic valve bioprosthesis in patients with severe calcific aortic stenosis. Antegrade transeptal approach was used under local anesthesia and mild sedation. (J Interven Cardiol 2003;16:515–521)
Advances in Heart Valve Surgery
Authors: AAZAMI MATTHIAS , SCHÄFERS HANS‐JOACHIM
Published: November 2003

Heart valve surgery continues to evolve in a dynamic fashion. While the exact role of minimally invasive approaches still needs to be defined, progress has been made in the development of new bioprostheses and their durability. Most importantly, valve repair has been standardized for the mitral and introduced for the aortic valve with results that have been superior to valve replacement. Selection of the optimal procedure for the individual patient is now facilitated. In the future, a wider application of repair procedures and further improvements of biologic valves can be anticipated not only to influence long‐term results but also the decision‐making process for conservative or surgical treatment. (J Interven Cardiol 2003;16:535–541)
Percutaneous Closure of the Left Atrial Appendage
Authors: OSTERMAYER STEFAN , RESCHKE MADLEN , BILLINGER KAI , TREPELS THOMAS , BÜSCHEK FRANZISKA , BAYARD YVES , SIEVERT HORST
Published: November 2003

Patients with atrial fibrillation (AF) are at high risk of stroke. More than 15% of all strokes are due to atrial fibrillation. So far anticoagulation is the treatment of choice with a risk reduction of almost 70%. On the other hand, anticoagulation has many side effects such as intracranial or gastrointestinal hemorrhage. Closing the left atrial appendage (LAA) might be an alternative in patients who cannot take anticoagulation treatment due to contraindications or conditions in which the hazard of hemorrhage is greater than the potential clinical benefit. The PLAATO™ system (Percutaneous Left Atrial Appendage Transcatheter Occlusion) is a new device to close the LAA by the catheter technique. The device consists of a self‐expandable nitinol cage that is covered with ePTFE™. It is delivered via a specially designed 12F transseptal sheath. Small anchors along the struts prevent the occluder from embolizing. After device implantation patients are placed on aspirin only. The results of the dog model and the first clinical experiences in humans have been very promising. (J Interven Cardiol 2003;16:553–556)
Treatment of Bifurcation Coronary Lesions:
Authors: MELIKIAN NARBEH , MARIO CARLO Di
Published: November 2003

Percutaneous treatment of coronary bifurcation lesions, pose a number of technical challenges to the interventional cardiologist. Each lesion has to be approached with its own, targeted solution in the context of the clinical picture, anatomy, and pathology. To achieve acceptable clinical outcomes a number of established techniques are available. The exact anatomy of the lesion determines the technique used. The most common approach is to stent the main vessel across the ostium of the side branch. The side branch can be additionally treated with a second stent or balloon angioplasty depending on the severity of the ostial lesion and/or evidence of active ischemia. Other techniques involve stenting the main branch up to the carina but sparing the side branches, multiple ‘kissing stent’ approaches (‘Y’,‘T’, and ‘V’) or the ‘culottes’ technique. Follow‐up data demonstrates a high (over 90%) technical success rate. Clinical outcome is variable but with conventional stents restenosis rates higher than 30% have been reported in most studies and there is no added advantage in routine stenting of both main vessel and side branch. Recent introduction of drug‐eluting stents has resulted in a lower event rate and reduction of main vessel restenosis in comparison with historical controls. Side branch ostial restenosis remains a problem, which may require the development of novel ‘bifurcate’ stent designs to allow complete coverage with a single stent. (J Interven Cardiol 2003;16:507–513)
Direct Stent Implantation Using the EXPRESS™ Coronary Stent System:
Authors: SILBER SIGMUND , GRUBE EBERHARD , MARCO JEAN , GROLLIER GILLES , MORICE MARIE‐CLAUDE , SERRUYS PATRICK , COBAUGH MICHAEL , WIJNS WILLIAM
Published: November 2003

The aim of this prospective, multicenter, single arm study was to assess the safety and feasibility of EXPRESS™ Coronary Stent implantation in native coronary arteries without balloon predilatation. Forty‐two patients with de novo or restenotic lesions were enrolled, of which 38 were eligible for analysis. The coronary lesions were predominantly complex, occurring in arteries with a mean reference diameter of 2.80 ± 0.49 mm. Technical and procedural success were achieved in 89.5% and 84% of the cases respectively. The mean minimal lumen diameter increased from 1.08 ± 0.26 mm to 2.55 ± 0.44 mm and diameter stenosis decreased from 61 ± 7% to 13 ± 8%. The primary endpoint of major adverse cardiac events at 30 days was 2.6% and was limited to only one event (target vessel revascularization, nontarget lesion). No other MACE were observed during the three‐month follow‐up period. Based on the findings of this study, direct stenting with the EXPRESS™ Stent appears feasible and is well tolerated. (J Interven Cardiol 2003;16:491–497)
Long‐Term Outcome after Implantation of Bare Metal Stents for the Treatment of Coronary Artery Disease:
Authors: HAASE JÜRGEN , JUNG TOBIAS , STÖRGER HANS , HOFMANN MANFRED , REINEMER HARALD , SCHWARZ CLAUS‐EBERHARD , SCHÖPF JOSEF , SCHWARZ FRANZ
Published: November 2003

Background:

The widespread use of drug‐eluting stents in patients with coronary artery disease (CAD) is hampered by unequal regulations for reimbursement. Identification of patients with maximal benefit from this technology may be achieved by assessing long‐term clinical outcome after implantation of uncoated bare metal stents.

Patients and Methods:

A consecutive series of 1,000 patients with CAD treated with bare metal coronary stents of various designs from January 1995 to December 1995 was retrospectively followed over 4 years. The primary end points of the study were major adverse cardiac events.

Results:

The mean age of patients was 62 ± 10.3 years, 77.5% were male, and 18% were diabetic. Clinical follow‐up was obtained in 821 patients (82.1%) after 4.6 ± 1.1 years. During this period of time, 31.8% were admitted for repeat PCI, 15.1% underwent CABG operation, 3.5% had myocardial infarctions, and 3.7% died. At 4 years, 46.3% of diabetic patients survived without event versus 57.6% of nondiabetic patients (P < 0.05). Patients with CAD I survived without event in 65.3% versus 54.0% of patients with CAD II and 48.5% of patients with CAD III (P < 0.02).

Conclusion:

Implantation of uncoated stents provides the worst long‐term clinical outcome in patients with diabetes and those with multivessel CAD. Both groups of patients appear to be primary candidates for the use of drug‐eluting stents. (J Interven Cardiol 2003;16:469–473)
Relation Between Abnormal Ventricular Impulse Conduction and Heart Failure
Authors: VERNOOY KEVIN , VERBEEK XANDER A.A.M. , PESCHAR MAAIKE , PRINZEN FRITS W.
Published: November 2003

Ventricular pacing and left bundle branch block (LBBB) are two of the most common causes of asynchronous electrical activation of the ventricles. The sequence of activation is an important determinant of cardiac pump function. The sequence of activation during LBBB and during pacing at the conventional pacing site, the RV apex, is similar. In this article the literature on the effect of RV pacing and LBBB on regional and global LV pump function, on long‐term adaptations (remodeling) and on their possible contribution to the development of heart failure is discussed. Evidence is increasing that asynchronous electrical activation contributes significantly to the development of heart failure. (J Interven Cardiol 2003;16:557–562)
Steroids in the intestinal tract of rats are affected by dietary-fibre-rich barley-based diets
Authors: Dongowski Gerhard , Huth Mario , Gebhardt Erich
Published: November 2003

The aim of the present study was to investigate the influence of dietary-fibre (DF)-rich barley-based diets on bile acids (BA) and neutral sterols (NS) in the intestinal tract of rats. For this purpose, young male Wistar rats (n50; ten per group) weighing about 67g were fed either a barley-free diet (control group) or diets containing 500g barley meal extrudates/kg or a barley meal–Novelose mixture (groups A–D) for 6 weeks. These barley products contained 7–24g resistant starch/100g and 7–12g (1→3),(1→4)-β-glucan/100g. More steroids were transported towards the lower parts of the intestinal tract when higher concentrations of macromolecular DF were present in the diets (P<0·001). Tauroconjugated and primary BA dominated in the contents of the small intestine. Intense enzymic conversion of BA occurred in the caecum and colon. The fermentation of DF affected indirectly the amount of formed secondary BA. The main BA present in the caecal contents were muricholic acids, hyodeoxycholic acid and cholic acid. The BA spectrum in the colonic contents was different from that in the caecum. A higher concentration of NS appeared in the intestinal contents of the groups fed the barley-based diets than in the controls (P<0·005). The microbial conversion of cholesterol to coprostanol, cholestanone and coprostanone was influenced by the amount and composition of the DF in the gut. DF in the diet may affect the concentration and spectrum of steroids in the intestinal tract. The results are relevant for the discussion of mechanisms behind the cholesterol-lowering effects of DF.
Cs6Mo27S31: a novel ternary reduced molybdenum sulfide containing Mo9 and Mo18 clusters
Authors: Picard S. , Salloum D. , Gougeon P. , Potel M.
Published: November 2003

The crystal structure of hexacaesium heptacosamolybdenum hentriacontasulfide, Cs6Mo27S31, consists of a mixture of Mo9S11S6 and Mo18S20S6 cluster units in a 1:1 ratio. The units are connected through Mo—S bonds. Cs+ cations occupy large voids between the different cluster units.
[Yb(H2O)8][Cd3Cl9(H2O)]·6H2O
Authors: Yahyaoui Samia , Ben Hassen Rached , Donnadieu Bruno , Daran Jean-Claude , Ben Salah Abdelhamid
Published: November 2003

The title compound, namely octaaquaytterbium(III) aquanonachlorotricadmate(II) hexahydrate, [Yb(H2O)8][Cd3Cl9(H2O)]·6H2O, was prepared by evaporation at 278 K from an aqueous solution of the ternary system YbCl3–CdCl2–H2O and was characterized by elemental chemical analysis and by X-ray powder and single-crystal diffraction studies. The crystal structure can be viewed as being built from layers of double chains of CdCl6 and CdCl5(H2O) octahedra separated by antiprismatic [Yb(H2O)8]3+ cations. The stabilization of the structure is ensured by O—H...O and O—H...Cl hydrogen bonds. A comparison with the structures of SrCd2Cl6·8H2O and CeCd4Cl11·13H2O is presented.
4-(Piperidin-1-yl)pyridinium hexafluorophosphate at 150 K
Authors: James Bruce D. , Mutrofin Siti , Skelton Brian W. , White Allan H.
Published: November 2003

Structural characterization of the title compound, C10H15N2
+·PF6
−, shows it to be ionic, with the pyridine rather than the piperidine N atom being protonated and forming hydrogen bonds to the counter-ions, resulting in two independent ion pairs. A number of unusual features are noted, in particular the remarkably close inter-ring hydrogen contacts [1.97 (3)–2.00 (3) Å] and the considerable differences in the pair of cations, in respect of the torsion angles within the piperidine ring involving the bonds to either side of the N atom.
A new norkaurane-γ-lactone from Parinari sprucei
Authors: Mattia Carlo Andrea , Braca Alessandra , De Tommasi Nunziatina , Puliti Raffaella
Published: November 2003

The title tetracyclic diterpenoid, 10,13,16,17-tetrahydroxy-9-methyl-15-oxo-20-norkaurane-18,10-carbolactone hemihydrate, C20H28O6·0.5H2O, is a plant metabolite from Parinari sprucei, part of the Venezuelan Amazon flora. The asymmetric unit consists of two nearly identical molecules of the diterpenoid and one molecule of water. Some of the geometric parameters reflect steric strain in the molecule. The extended structure is characterized by hydrogen bonds and weaker hydrogen-mediated interactions, which involve all of the hydroxy groups and propagate in sheets that coincide with the (002) family of planes. The water molecule acts as a double hydrogen-bond donor and single acceptor and thus plays a critical role in the pattern of intermolecular interactions.
Dichlorobis(imidazolidin-2-one-κO)zinc(II) at 150 K
Authors: Falvello Larry R. , Miqueleiz Eva M. , Soler Tatiana , Tomás Milagros
Published: November 2003

In the title compound, [ZnCl2(C3H6N2O)2], the zinc(II) cation is surrounded by a distorted tetrahedral environment consisting of two Cl anions and two imidazolidin-2-one molecules, the latter bound to the metal through their carbonyl O atoms. All atoms that are able to participate in hydrogen bonding are involved in such interactions. A hydrogen-bonding network mediates the formation of molecular columns parallel to the a axis. Neighboring columns are not bound by significant non-covalent interactions; the result is an extended pattern of supramolecular aggregation that is intermediate in completeness between the situations observed in two related complexes of cobalt that have been studied previously.
Diaquabis(1,10-phenanthroline-κ2
N,N′)manganese(II) thiodiglycolate bis(1,10-phenanthroline-κ2
N,N′)(thiodiglycolato-κ2
O,O′)manganese(II) tridecahydrate
Authors: Marek Jaromír , Trávníček Zdeněk , Kopel Pavel
Published: November 2003

The title compound, [Mn(C12H8N2)2(H2O)2](C4H4O4S)·[Mn(C4H4O4S)(C12H8N2)2]·13H2O, contains one dianion of thiodiglycolic acid (tdga2−) and two independent manganese(II) moieties, viz. [Mn(phen)2(H2O)2]2+ and [Mn(tdga)(phen)2], where phen is 1,10-phenanthroline. The MnII atoms are octahedrally coordinated by four N atoms of two bidentate phen ligands [Mn—N = 2.240 (2)–2.3222 (19) Å] and either two water O atoms or two tdga carboxyl O atoms [Mn—O = 2.1214 (17)–2.1512 (17) Å]. The tdga ligand chelates as an O,O′-bidentate ligand, forming an eight-membered ring with one Mn atom. The free tdga2− dianion is hydrogen bonded to an [Mn(phen)2(H2O)2]2+ ion, with O...O distances of 2.606 (2) and 2.649 (2) Å. The crystal structure is further stabilized by an extensive network of hydrogen bonds involving 13 water molecules.
A non-linear optical crystal, Cd3Zn3(BO3)4
Authors: Sun Tongqing , Pan Feng , Wang Ruji , Shen Guangqiu , Wang Xiaoqing , Shen Dezhong
Published: November 2003

The title compound, tricadmium trizinc tetraborate, Cd3Zn3(BO3)4, is a new non-linear optical (NLO) crystal and its structure has been determined by single-crystal X-ray diffraction. This compound is composed of planar [BO3]3− groups sharing O atoms with CdO4 or ZnO4 tetrahedra. The BO3 triangles are located on threefold axes and are arranged with nearly the same orientation. The Cd and Zn atoms are disordered on the same site in the proportion 1:1. A strong second harmonic generation of Nd:YAG laser radiation (λ = 1064 nm) has been observed for a crystal of the title compound.
Magnesium iodide–4,4′-bipyridine–water (1/3/4) and strontium iodide–4,4′-bipyridine–propan-1-ol (1/2.5/2)
Authors: Skelton Brian W. , Waters A. Fiona , Whitaker Claire R. , White Allan H.
Published: November 2003

Both of the title compounds, catena-poly[[[tetraaquamagnesium(I)]-μ-4,4′-bipyridine-κ2
N:N′] diiodide bis(4,4′-bipyridine) solvate], {[Mg(C10H8N2)(H2O)4]I2·2C10H8N2}
n
, (I), and catena-poly[[[μ-4,4′-bipyridine-bis[diiodobis(propan-1-ol)strontium(I)]]-di-μ-4,4′-bipyridine-κ4
N:N′] bis(4,4′-bipyridine) solvate], {[Sr2I4(C10H8N2)3(C3H8O)4]·2C10H8N2}
n
, (II), are one-dimensional polymers which are single- and double-stranded, respectively, the metal atoms being linked by the 4,4′-bipyridine moieties. The Mg complex, (I), is [cis-{(H2O)4Mg(N-4,4′-bipyridine-N′)(2/2)}](
∞|∞
)I2·4,4′-bipyridine and Mg has a six-coordinate quasi-octahedral coordination environment. The Sr complex, (II), is isomorphous with its previously defined Ba counterpart [Kepert, Waters & White (1996). Aust. J. Chem.
49, 117–135], being [(propan-1-ol)2I2Sr(N-4,4′-bipyridine-N′)(3/2)](
∞|∞
)·4,4′-bipyridine, with the I atoms trans-axial in a seven-coordinate pentagonal–bipyramidal Sr environment.