bluuebunny/crossref_metadata_2025 huggingface dataset:
Perforation patterns in the peptidoglycan wall of filamentous cyanobacteria
Authors: Palinska Katarzyna A. , Krumbein Wolfgang E.
Published: March 2003

Ultrastructural studies were made on seven genera of filamentous cyanobacteria from Sections III and IV (in the Rippka classification): Oscillatoria limosa Ag. ex Gomont, Spirulina subsalsa Turp. ex Gomont, Crinalium epipsammum Crow, Nostoc commune Vaucher ex Born. et Flah., Anabaena variabilis Kützinger ex Born. et Flah., Arthrospira maxima Stizenb. ex Gomont, Arthrospira platensis Stizenb. ex Gomont, and Cyanospira rippkae Florenzano. Perforation types and their distribution in the peptidoglycan layer observed in Crinalium epipsammum Crow were similar to those in Oscillatoria limosa and two Arthrospira strains. In Cyanospira and Anabaena no junctional perforations in the peptidoglycan wall layer were observed; however, intracellular perforations were documented. Except for Spirulina, the perforations were organized in rows (up to 10) placed on both sides of the cross wall. In the Spirulina cross sections, perforations were found only in the thickened, inner part of the cell wall. The perforation patterns in Spirulina and Arthrospira strains were clearly different and justify the separation into different genera.
ACCUMULATION AND REDUCTION OF ARSENATE BY THE FRESHWATER GREEN ALGA CHLORELLA SP. (CHLOROPHYTA)
Authors: Knauer Katja , Hemond Harry
Published: March 2003

Arsenate accumulation and reduction kinetics at both high and low phosphate concentrations were investigated in the green alga Chlorella sp, isolated from the arsenic‐contaminated Upper Mystic Lake near Boston, MA. Growth rate, accumulated cellular arsenic, and release of As(III) were determined over a range of arsenate concentrations. Arsenate inhibited growth and reduced final cell yield at high phosphate concentration. However, growth rate, final cell yield, and cellular arsenic content were all enhanced by higher arsenate concentrations in cultures grown at a low concentration of phosphate. The traditional view that phosphate‐limited cells are necessarily more sensitive to As(V) toxicity may not be correct. The reduction rates of As(V) by Chlorella sp. obtained in our laboratory were similar to net reduction rates measured in epilimnetic water from the Upper Mystic Lake, demonstrating the importance of phytoplankton in arsenic reduction in freshwater.
Cell cycle regulation and the timing of chromosome replication in a marine synechococcus (cyanobacteria) during light‐ and nitrogen‐limited growth
Authors: Binder Brian
Published: March 2003

Cell cycle behavior in the marine Synechococcus strain WH8101 was examined in detail over a wide range of light‐ and nitrogen‐limited growth rates. The presence of bimodal DNA frequency distributions under all conditions confirms that the overlapping rounds of DNA replication that characterize E. coli and other fast‐growing prokaryotes are not present in this organism. Although chromosome replication time, C, was constrained to a fairly narrow range of values overall, it nevertheless did vary with growth rate and limiting factor. Light‐limited cells growing at moderate rates had higher C values than did N‐limited cells growing at comparable rates (by as much as a factor of 2). As these cells became light saturated, however, C decreased sharply to the level observed under N limitation. The post‐replication period, D, decreased monotonically with growth rate under both light and N limitation, approaching a constant value at moderate to high growth rates. Average cell volume at the time of initiation of DNA replication was calculated from the values of C and D, combined with directly measured mean cell volume, and was found to be constant at all growth rates above ∼0.7 d−1. This pattern was confirmed by estimates of initiation volume based on flow cytometric light scatter measurements, and suggests that as has been found in other prokaryotic systems, cell mass may play an important role in regulating the timing of chromosome replication in cyanobacteria. Furthermore, because the magnitude of C+D influences average cell mass (given a constant mass at initiation), changes in these parameters (particularly C) may be responsible for the previously reported nonlinear relationship between light‐limited growth rate and both RNA cell−1 and average cell volume.
WATER MOTION, MARINE MACROALGAL PHYSIOLOGY, AND PRODUCTION
Authors: Hurd Catriona L.
Published: March 2003

Water motion is a key determinant of marine macroalgal production, influencing directly or indirectly physiological rates and community structure. Our understanding of how marine macroalgae interact with their hydrodynamic environment has increased substantially over the past 20 years, due to the application of tools such as flow visualization to aquatic vegetation, and in situ measurements of seawater velocity and turbulence. This review considers how the hydrodynamic environment in which macroalgae grow influences their ability to acquire essential resources and how macroalgae might respond physiologically to fluctuations in their hydrodynamic regime with a focus on: (1) the biochemical processes occurring within the diffusion boundary layer (DBL) that might reduce rates of macroalgal production; (2) time scales over which measurements of velocity and DBL processes should be made, discussing the likelihood of in situ mass transfer limitation; (3) if and how macroalgal morphology influences resource acquisition in slow flows; and (4) ecobiomechanics and how hydrodynamic drag might influence resource acquisition and allocation. Finally, the concept that macroalgal production is enhanced in wave‐exposed versus sheltered habitats is discussed.
GAMETE RELEASE IS INCREASED BY CALM CONDITIONS IN THE COENOCYTIC GREEN ALGA BRYOPSIS (CHLOROPHYTA)
Authors: Speransky Svetlana R. , Brawley Susan H. , Halteman William A.
Published: March 2003

Water motion did not inhibit gamete release in cultures of the coenocytic green alga Bryopsis plumosa (Hudson) C. Agardh; however, the number of gametangia that released gametes increased significantly under transiently calm conditions. This stimulatory effect of calm conditions in the laboratory was found in isolates from two different areas of the Maine coast. The isolates were all monoecious, but strong differences in levels of fertilization, numbers of male and female gametes remaining following fertilization, and levels of polygamy (=zygotes formed by fusions of more than two gametes) were observed among isolates. These data support the hypothesis that organisms with external fertilization are able to sense and respond to water motion in ways that favor reproductive success.
Sexual hybridization experiments and phylogenetic relationships as inferred from rubisco spacer sequences in the genus alaria (phaeophyceae)
Authors: Kraan Stefan , Guiry Michael D.
Published: March 2003

Alaria (Alariaceae, Phaeophyceae) is a common genus of kelps generally found in the lower intertidal and shallow subtidal regions of rocky shores subject to strong wave exposure. Fourteen species are currently recognized, of which 11 are found in the cold–temperate North Pacific Ocean. Alaria esculenta (L.) Greville, the type species described from the North Atlantic, exhibits a range of biogeographically correlated morphotypes indicating the possibility of multiple species, subspecies, and/or hybrids. This has led to an unstable taxonomy. We compared five species from the Atlantic and Pacific, including six North Atlantic isolates of A. esculenta. Phylogenetic analyses based on Rubisco spacer sequences resulted in a well‐resolved topology of these five species, but did not distinguish between the six biogeographic isolates of A. esculenta. Laboratory hybridization experiments among four A. esculenta isolates showed partial intrafertility. Among five tested Alaria species, interfertility as well as fertility barriers were encountered, inconsistent with reproductive isolation. The data reject both a biological and morphological species concept and support only a phylogenetic species concept for Alaria, demonstrating that morphological variation has evolved independently of molecular variation in the genes under investigation in the species of the genus Alaria.
GENETIC VARIABILITY OF BRAZILIAN STRAINS OF THE MICROCYSTIS AERUGINOSA COMPLEX (CYANOBACTERIA/CYANOPHYCEAE) USING THE PHYCOCYANIN INTERGENIC SPACER AND FLANKING REGIONS (cpcBA)
Authors: Do Carmo Bittencourt‐Oliveira Maria , De Oliveira Mariana Cabral , Bolch Christopher J. S.
Published: March 2003

The genetic and morphological variability among 15 Brazilian strains of Microcystis aeruginosa (Kütz.) Kütz. collected from four locations was examined and compared with several reference strains of M. aeruginosa, M. viridis (A. Br.) Lemm. and M. wesenbergii (Kom.) Kom. in Kondr. Brazilian strains were classified by morphological features and by comparison of the nucleotide sequences of the cpcBA intergenic spacer and flanking regions. Our results indicate that Brazilian strains classified as M. aeruginosa are phylogenetically diverse compared with reference strains of M. aeruginosa and that the current taxonomy underestimates genetic diversity within M. aeruginosa. The data also demonstrate that morphological criteria alone are inadequate to characterize Microcystis species. Although colonial characters were shown to vary considerably in culture, some genetic lineages demonstrated consistent cellular diameter ranges, indicating that cell size has value as a taxonomic character. The detection of six M. aeruginosa genotypes in a single water body indicates that morphological approaches can also seriously underestimate the diversity of Microcystis bloom populations.
PHYLOGENY OF THE CHLOROPHYCEAE WITH SPECIAL REFERENCE TO THE SPHAEROPLEALES: A STUDY OF 18S AND 26S rDNA DATA
Authors: Buchheim Mark A. , Michalopulos Eugenia A. , Buchheim Julie A.
Published: March 2003

Ultrastructural analyses of the flagellar apparatus suggested that Sphaeroplea, Atractomorpha, the Hydrodictyaceae, and the Neochloridaceae, all of which produce biflagellate motile cells with directly opposed (DO) basal bodies, are allied in an order Sphaeropleales. Recent studies of 18S rDNA sequence data supported an alliance of the DO group, but no data from Sphaeroplea and its allies were included. This investigation presented a test of the phylogenetic hypothesis suggested by the flagellar apparatus evidence using sequence data from the nuclear‐encoded small‐subunit rDNA (18S) and large subunit rDNA (26S) genes, combined with additional taxon sampling. Results from phylogenetic analyses weakly supported monophyly of biflagellate DO taxa and indicated that pyrenoids with cytoplasmic invaginations are present in numerous distinct lineages. Analysis of both molecular data sets supported a class Chlorophyceae comprised of at least six major groups that generally correspond to currently recognized orders or families: Chaetophorales, Chae‐ topeltidales, Chlamydomonadales, Sphaeropleales, Sphaeropleaceae, and Oedogoniales. In addition, Cylindrocapsa, Elakatothrix, Treubaria, and Trochiscia formed a seventh chlorophycean clade that is new to science. This investigation demonstrated that the 26S rDNA gene provides more phylogenetic signal, per unit sequence, than the 18S rDNA gene and that combined analysis yields topologies with more robust support than independent analysis of either data set.
THERMOGEOGRAPHY OVER TIME CREATES BIOGEOGRAPHIC REGIONS: A TEMPERATURE/SPACE/TIME‐INTEGRATED MODEL AND AN ABUNDANCE‐WEIGHTED TEST FOR BENTHIC MARINE ALGAE
Authors: Adey Walter H. , Steneck Robert S.
Published: March 2003

We developed a time‐integrated thermogeographic model to demonstrate conditions under which benthic marine algal assemblages evolve biogeographic patterns in their distribution and abundance. The graphical model applies to rocky marine sublittoral zones in which seasonal temperatures, coastline area, isolation, and evolutionary time are primary factors. Time is treated by using the temperature/area/distributions for the present (interglacial period) integrated with that of 18,000 years before present (glacial period). These two alternate states characterize the global marine realm since the late Pliocene to Pleistocene time during which many extant species have evolved. The resulting abiotic “thermogeographic” model defines 20 regions that correspond with the cores of 24 recognized biogeographic regions and/or provinces determined by published distributions of organisms. Modern biogeographic regions conform closely with thermogeographic regions where temperature, area, and time are integrated. We also propose that biogeographic patterns should be determined by the abundance of species assemblages rather than presence and absence or percent endemism as is commonly done. We test the efficacy of thermogeographic regions with abundance‐weighted patterns in the biogeography of crustose coralline red algae (Rhodophyta/Corallinales) in the colder part of the northern hemisphere. Based on abundance, rather than presence/absence, coralline red algal biogeographic regions correspond closely with the model's thermogeographic regions.
ALGAE KNOW THE TIME OF DAY: CIRCADIAN AND PHOTOPERIODIC PROGRAMS
Authors: Suzuki Lena , Johnson Carl Hirschie
Published: March 2003

Eukaryotic algae have long served as model systems for analyses of circadian (daily) rhythms of many phenomena, including rhythmic gene expression, cell division timing, taxes, photosynthesis, and others. More recently, circadian clocks have been demonstrated in cyanobacteria, and rapid progress on the characteristics and mechanism of timekeeping in these prokaryotic algae ensued. These daily timekeepers enhance the fitness of algae and may contribute to seasonal responses.
EVOLUTIONARY RELATIONSHIPS AMONG MULTIPLE MODES OF CELL DIVISION IN THE GENUS NANNOCHLORIS (CHLOROPHYTA) REVEALED BY GENOME SIZE, ACTIN GENE MULTIPLICITY, AND PHYLOGENY
Authors: Yamamoto Maki , Nozaki Hisayoshi , Kawano Shigeyuki
Published: March 2003

A single cell divides to multiply, but not all cells follow the same pattern of division. We studied cell division in seven strains from six species belonging to the genus Nannochloris Naumann and classified their modes of cell division into three types: binary fission (N. bacillaris Naumann), budding (N. coccoides Naumann), and autosporulation resulting in the formation of two to four daughter cells (N. maculata Butcher, N. sp. SAG 251‐2, N. atomus Butcher CCAP 251/7 and SAG 14.87, and N. eucaryotum[Wilhelm et al.] Menzel and Wild). To determine the evolutionary relationships among these multiple modes of cell division, we investigated the strains' genome sizes, copy number of actin genes, and phylogeny. The genome sizes were determined by counter‐clamped homogeneous electric fields electrophoresis and fluorimetry. The genomes are very small and range from 12.6 Mbp (N. maculata) to 47.4 Mbp (N. atomus SAG 14.87). The genomes of Nannochloris species seem to be among the smallest for free‐living eukaryotes. Nannochloris bacillaris (binary fission), N. coccoides (budding), Nannochloris sp. (two‐cell type of autosporulation), and N. eucaryotum (multicell type of autosporulation) contain a single actin gene, whereas N. maculata (two‐cell type of autosporulation) and two strains of N. atomus (two‐cell type of autosporulation) contain two actin genes. This suggests that the actin gene was duplicated in this eukaryote, which has a very small genome. Phylogenetic analyses of partial actin gene sequences suggest that autosporulation is the ancestral mode of cell division.
REDUCTION AND TRANSPORT OF ORGANICALLY BOUND IRON BY THALASSIOSIRA OCEANICA (BACILLARIOPHYCEAE)
Authors: Maldonado Maria T. , Price Neil M.
Published: March 2003

Thalassiosira oceanica (Hustedt) Hasle et Heimdal (clone 1003) attained rapid rates of growth in low Fe seawater containing the siderophore ferrioxamine B (FeDFB) as the sole Fe source. Short‐term rates of Fe uptake were 109 times faster than those predicted from the equilibrium concentration of inorganic Fe, suggesting that FeDFB was the substrate for the Fe transport system. An extracellular reduction step, mediated by a cell surface reductase, preceded Fe transport from FeDFB and was induced under Fe limitation. The half‐saturation constant for the reduction was 0.68 μM. Iron reduction rates were two times faster than uptake rates, so that the activities of the reductase and the transporter were tightly coupled. The rates of Fe reduction of a number of Fe chelators, including synthetic organic ligands (nitrilotriacetate, diethylenetriaminepentaacetate, and EDTA) and fungal siderophores (desferrioxamine B and desferrioxamine E), were inversely proportional to the ratio of the stability constants of their Fe(III) and Fe(II) complexes and varied by a factor of two times, like the redox potentials of the Fe complexes. Platinum (II), a known inhibitor of Fe reductase activity, appeared to reduce the rates of Fe uptake from FeDFB but not from inorganic complexes. The results suggested that reoxidation of Fe(II) produced by reduction may be a necessary part of the Fe internalization reaction. Ferric reductase could be relevant to phytoplankton nutrition in the open sea where organic Fe complexes dominate the dissolved speciation and where the concentration of inorganic Fe is limiting.
IDENTIFICATION AND CLONING OF AMPLIFIED FRAGMENT LENGTH POLYMORPHISM MARKERS LINKED TO THE MATING TYPE LOCUS OF CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)
Authors: Werner Ralf , Olschewski Jasna , Mergenhagen Dieter
Published: March 2003

Amplified fragment length polymorphism (AFLP) markers have been widely used to generate molecular maps of plant species, including crops and cereals. We report on a useful protocol to identify AFLPs from Chlamydomonas reinhardtii Dangeard with digoxigenin labeled primers. Although Chlamydomonas has a small genome with a high GC content, we could detect polymorphic bands that led to the identification of several AFLP markers linked to the mating type locus of Chlamydomonas. Three of these markers were isolated from the gel, reamplified, and cloned. The clones were sequenced, and the insertion of the correct fragment was verified in AFLP gels and in Southern blots. One marker showed sequence identity to parts of the fus1 gene, known to be unique in the plus mating type. We also converted some of the AFLP markers into sequence tagged site markers, which allows a fast and convenient screening of progeny of crosses. This procedure will be a useful and fast alternative to the conventional generation of maps for the positional cloning of genes from Chlamydomonas.
ONSLOWIACEAE FAM. NOV. (PHAEOPHYCEAE)
Authors: Draisma S. G. A. , Prud'Homme van Reine W. F.
Published: March 2003

We propose the separation of Onslowia and Verosphacella from the Choristocarpaceae and from the Sphacelariales based on comparisons of DNA sequences of rbcL and nrRNA genes and morphological considerations. The new family Onslowiaceae is created to include these two genera. The families Choristocarpaceae and Onslowiaceae are considered incertae sedis.
A PROPOSAL FOR A NEW RED ALGAL ORDER, THE THOREALES1
Authors: Müller Kirsten M. , Sherwood Alison R. , Pueschel Curt M. , Gutell Robin R. , Sheath Robert G.
Published: March 2003

Representatives of the freshwater red algal family Thoreaceae were studied to resolve their taxonomic and phylogenetic status. Three specimens of Nemalionopsis and five collections of Thorea were examined for pit plug ultrastructure and analyzed for the sequences of the genes coding for the large subunit of RUBISCO (rbcL) and the small subunit of rRNA (18S rRNA). The phylogenetic trees generated from the two genes, and a combined tree all showed the Thoreaceae to be contained in a well‐supported monophyletic clade that is separate from the other two families currently classified in the Batrachospermales, the Batrachospermaceae and the Lemaneaceae. In addition, secondary structure elements of the 18S rRNA gene were observed at positions 650 and 1145 (Escherichia coli numbering system) that are not present in other members of the Rhodophyta. The pit plugs of the gametophytic and chantransia stages of the Thoreaceae contain two cap layers, the outer one of which is typically plate‐like, though occasionally inflated ones have been seen. No pit plug cap membrane has been observed. These findings indicate the Thoreaceae has been misclassified in the Batrachospermales and should be placed in its own order, the Thoreales. This order is characterized by having freshwater representatives with multiaxial gametophytes, a uniaxial chantransia stage, and pit plugs with two cap layers, the outer one of which is usually plate‐like.
CYST–THECA RELATIONSHIP, LIFE CYCLE, AND EFFECTS OF TEMPERATURE AND SALINITY ON THE CYST MORPHOLOGY OF GONYAULAX BALTICA SP. NOV. (DINOPHYCEAE) FROM THE BALTIC SEA AREA1
Authors: Ellegaard Marianne , Lewis Jane , Harding Ian
Published: March 2003

A new species of Gonyaulax, here named Gonyaulax baltica sp. nov., has been isolated from sediment samples from the southeastern Baltic. Culture strains were established from individually isolated cysts, and cyst formation was induced in a nitrogen‐depleted medium. Although G. baltica cysts are similar to some forms attributed to Spiniferites bulloideus and the motile stage of G. baltica has affinities with G. spinifera, the combination of features of cyst and motile stage of G. baltica is unique. The culture strains were able to grow at salinity levels from 5 to 55 psu and formed cysts from 10 to 50 psu. Cultures at each salinity level were grown at 12, 16, and 20° C. Temperature‐ and salinity‐controlled morphological variability was found in the resting cysts. Central body size varied with temperature and salinity, and process length varied with salinity. Cysts that formed at extreme salinity levels displayed lower average process length than cysts formed at intermediate salinity levels, and central body length and width were lowest at higher temperature and lower salinity. Models for the relationship between central body size and temperature/salinity and process length and salinity have been developed and may be used to determine relative paleosalinity and paleotemperature levels. Our results on salinity‐dependent process length confirm earlier reports on short‐spined cysts of this species found in low salinity environments, and the model makes it possible to attempt to quantify past salinity levels.
PHYLOGENETIC RELATIONSHIPS AMONG STREPTOPHYTES AS INFERRED FROM CHLOROPLAST SMALL AND LARGE SUBUNIT rRNA GENE SEQUENCES1
Authors: Turmel Monique , Ehara Megumi , Otis Christian , Lemieux Claude
Published: March 2003

To gain insights into the phylogeny of charophytes and into their relationships with other green algae and bryophytes, we analyzed the chloroplast small and large subunit rRNA sequences of charophytes belonging to five orders (Charales, Coleochaetales, Desmidiales, Klebsormidiales, and Zygnematales), of chlorophytes from the four remaining classes of green algae, and of bryophytes representing the three classes reported in this group of land plants. We also probed the gene organization and intron content of the chloroplast rDNA operon in charophytes and bryophytes. The organization of this operon proved to be highly conserved, except in members of the Desmidiales and Zygnematales. Homologous group II introns were identified in thetrnA(UGC) gene of all charophyte groups examined and in thetrnI(GAU) gene of charophytes from all orders except the Desmidiales and Zygnematales. Phylogenetic analyses of concatenated rDNA sequences consistently placed the prasinophyteMesostigma virideLauterborn at the base of the Streptophyta and Chlorophyta, although alternative topologies positioningMesostigmawithin the Streptophyta could not be rejected. A sister group relationship was unambiguously established betweenChaetosphaeridium globosum(Nordstedt) Klebahn and members of the Coleochaetales. The Charales, Coleochaetales, Desmidiales, and Zygnematales were found to be monophyletic, and a sister group relationship was observed for the Desmidiales and Zygnematales. Although our analyses failed to resolve the branching order of the Coleochaetales, Charales, Desmidiales/Zygnematales, and bryophytes, they revealed that the problematic charophyte taxonEntransia fimbriataHughes strongly clusters withKlebsormidium flaccidum(Kützing) Silva, Mattox et Blackwell to form a basal lineage relative to the other charophyte orders examined.
PHYLOGENY AND GENETIC VARIANCE IN TERRESTRIAL MICROCOLEUS (CYANOPHYCEAE) SPECIES BASED ON SEQUENCE ANALYSIS OF THE 16S rRNA GENE AND ASSOCIATED 16S–23S ITS REGION1
Authors: Boyer Sarah L. , Johansen Jeffrey R. , Flechtner Valerie R. , Howard Gwyn L.
Published: March 2003

Thirty‐one strains of Microcoleus were isolated from desert soils in the United States. Although all these taxa fit the broad definition of Microcoleus vaginatus (Vaucher) Gomont in common usage by soil algal researchers, sequence data for the 16S rRNA gene and 16S–23S internal transcribed spacer (ITS) region indicated that more than one species was represented. Combined sequence and morphological data revealed the presence of two morphologically similar taxa, M. vaginatus and Microcoleus steenstrupii Boye‐Petersen. The rRNA operons of these taxa were sufficiently dissimilar that we suspect the two taxa belong in separate genera. The M. vaginatus clade was most similar to published sequences from Trichodesmium and Arthrospira. When 16S sequences from the isolates we identified as M. steenstrupii were compared with published sequences, our strains grouped with M. chthonoplastes (Mertens) Zanardini ex Gomont and may have closest relatives among several genera in the Phormidiaceae. Organization within the 16S–23S ITS regions was variable between the two taxa. Microcoleus vaginatus had either two tRNA genes (tRNAIle and tRNAAla) or a fragment of the tRNAIle gene in its ITS regions, whereas M. steenstrupii had rRNA operons with either the tRNAIle gene or no tRNA genes in its ITS regions. Microcoleus vaginatus showed no subspecific variation within the combined morphological and molecular characterizations, with 16S similarities ranging from 97.1% to 99.9%. Microcoleus steenstrupii showed considerable genetic variability, with 16S similarities ranging from 91.5% to 99.4%. In phylogenetic analyses, we found that this variability was not congruent with geography, and we suspect that our M. steenstrupii strains represent several cryptic species.
PELAGIC AND BENTHIC ENVIRONMENTAL CONTROLS ON THE SPATIAL DISTRIBUTION OF A VIABLE DIATOM PROPAGULE BANK ON THE SWEDISH WEST COAST1
Authors: McQuoid Melissa R.
Published: March 2003

The distribution of viable diatom resting stages in sediments on the Swedish west coast was assessed by the most probable number (MPN) culture technique. Multivariate analyses correlated benthic and pelagic environmental factors to the observed spatial variations in the size and taxonomic composition of the propagule bank. Viable diatom resting stages were plentiful (0.2–4.8 million cells·g−1 dry weight) and were dominated by the genera Skeletonema, Detonula, Chaetoceros, and Thalassiosira. Size of the propagule bank was primarily related to planktonic biomass (measured as chl a) and was highest in the Orust‐Tjörn fjord system. Species composition in this fjord system was dominated by D. confervacea (Cleve) Gran and T. nordenskioeldii Cleve in contrast to stations on the outer coast, which contained more cells of T. minima Gaarder, Asterionellopsis glacialis (Castracane) Round, and Leptocylindrus danicus Cleve. These taxonomic variations were principally influenced by deep water oxygen concentrations and water column stability. Benthic resting cells of S. costatum (Greville) Cleve were abundant all along the coast but showed reduced viability in low oxygen environments. Calculations based on MPN values estimated that resuspension of sediment could provide a sizable inoculum to the plankton, although the development of planktonic blooms will also depend on forces of hydrography and weather. Although benthic resting stages may not be absolutely necessary for survival of all diatoms, these cells may be important in determining species cycles, succession, and the spatial distribution of diatoms.
A COMBINED 18S rDNA AND rbcL PHYLOGENETIC ANALYSIS OF CHLOROMONAS AND CHLAMYDOMONAS (CHLOROPHYCEAE, VOLVOCALES) EMPHASIZING SNOW AND OTHER COLD‐TEMPERATURE HABITATS1
Authors: Hoham Ronald W. , Bonome Tomas A. , Martin Christopher W. , Leebens‐Mack James H.
Published: March 2003

An extensive phylogenetic analysis of the biflagellate genera, Chlamydomonas Ehrenberg and Chloromonas Gobi emend. Wille, was undertaken using 18S rDNA and rbcL gene sequence analysis. Emphasis was placed on 21 cold‐tolerant taxa of which 10 are from snow. These taxa occurred in four distinct clades each in the 18S rDNA and rbcL phylogenies, and when taken together suggest at least five distinct origins in cold habitats. Most of these taxa occur in a single clade (A), and all snow species occurred in this clade. In the rbcL and combined rbcL–18S rDNA analyses, the snow taxa fell into three groups. Two groups occurred in subclade 1: Chlamydomonas augustae Skuja CU, Chlamydomonas augustae UTEX, and Chlamydomonas sp.‐A and Chloromonas clathrata Korshikov, Chloromonas rosae Ettl CU, and Chloromonas rosae v. psychrophila var. nov. The third snow group, subclade 2, included three species with unique cell divisions, Chloromonas brevispina (Fritsch) Hoham, Roemer et Mullet, Chloromonas pichinchae (Lagerheim) Wille, and Chloromonas sp.‐D, and the basal Chloromonas nivalis (Chodat) Hoham et Mullet with normal cell divisions. This suggests that the snow habitat has been colonized at least twice and possibly three times in the history of these biflagellates. In the 18S rDNA tree, one cold‐tolerant Chloromonas species fell outside clade A: Chloromonas subdivisa (Pascher et Jahoda) Gerloff et Ettl. In the rbcL tree, three cold‐tolerant Chloromonas species fell outside clade A: Chloromonas subdivisa, Chloromonas sp.‐ANT1, and Chloromonas sp.‐ANT3. These results support previous findings that pyrenoids have been gained and lost several times within this complex.
SYSTEMATICS OF GRACILARIOPSIS (GRACILARIALES, RHODOPHYTA) BASED ON rbcL SEQUENCE ANALYSES AND MORPHOLOGICAL EVIDENCE1
Authors: Gurgel Carlos Frederico D. , Liao Lawrence M. , Fredericq Suzanne , Hommersand Max H.
Published: March 2003

A phylogeny has been inferred from parsimony and likelihood analyses of plastid rbcL DNA sequences for seven recognized and six undescribed species of Gracilariopsis (Gp.) (Gracilariales, Rhodophyta). New descriptions and illustrations of cystocarp morphology are provided for four Gracilariopsis species from North and South America. The generitype, Gp. sjoestedtii (Kylin) Dawson, is reinstated to include plants distributed from British Columbia to Pacific Baja California, and the name is corrected to Gp. andersonii (Grunow) Dawson. Gracilariopsis lemaneiformis (Bory) Dawson, Acleto et Foldvik is shown not to have a worldwide distribution but to be restricted to the vicinity of Peru. Gracilariopsis costaricensis is recognized with the provision that it may prove to be conspecific with Gp. lemaneiformis. Gracilariopsis “lemaneiformis” from North and South Carolina is described as a new species, Gp. carolinensis Liao et Hommersand sp. nov. Gracilariopsis longissima (Gmelin) Steentoft, Irvine et Farnham from Western Europe and the Mediterranean Sea and Gp. tenuifrons (Bird et Oliveira) Fredericq et Hommersand from the Ca‐ribbean Sea and Brazil are recognized. Entities that have been referred to Gp. “lemaneiformis” from China and Japan constitute an undescribed species that is related to Gp. heteroclada Zhang et Xia. An invasive species from the Gulf of California, Mexico, and South Australia that has been assigned to Gp. “lemaneiformis” is resolved in a clade that includes Gp. longissima. Four undescribed species are included in the molecular analyses. The systematics of Gracilariopsis is discussed in the light of the morphological and molecular evidence.
INTERACTIONS OF THE MIX‐LINKED β‐(1,3)/β‐(1,4)‐d‐XYLANS IN THE CELL WALLS OFPALMARIA PALMATA(RHODOPHYTA)1
Authors: Deniaud Estelle , Fleurence Joel , Lahaye Marc
Published: March 2003

Algal cell wall mechanical properties, crucial for biological functions and commercial applications, rely on interactions in macromolecular assemblies. In an effort to better understand the interactions of the matrix‐phase β‐(1,3)/(1,4)‐d‐xylan in the edible seaweedPalmaria palmata((L.) O. Kuntze, Rhodophyta, Palmariales), sequential extractions by saline, alkaline, and chaotropic solutions were done. The chemical composition and structure and the physicochemical properties of the isolated xylan revealed that it was partly acidic, probably due to the presence of sulfate (up to 5%) and phosphate groups (up to 4%). Although such acidity suggested ionic interactions of xylan in the cell walls, the high yields of polysaccharide extracted by alkali and particularly by 8 M urea and 4.5 M guanidium thiocyanate demonstrated that it was mainly hydrogen bonded in the cell wall. H‐bonds did not appear to be related to the mean proportions of β‐(1,3) and β‐(1,4)‐d‐xylose linkages because these did not differ between extracts of increasing alkalinity. However, the decreasing molar weight and intrinsic viscosity of extracts obtained by alkaline solution containing a reducing agent used to prevent polysaccharide degradation suggested the presence of an alkali‐labile component in the xylan. These results are discussed with regard to the role of potential wall proteins as a means of control of these interactions.
The Relationship Between Body Mass Index and Self‐Reported Functional Limitation Among Older Adults: A Gender Difference
Authors: Friedmann Janet M. , Elasy Tom , Jensen Gordon L.
Published: March 2003

OBJECTIVES: To determine whether there is a gender difference in how body mass index (BMI) relates to self‐reported functional limitation. Also, to evaluate whether the method of categorizing BMI changes the observed results.

DESIGN: Cross‐sectional cohort study.

SETTING: Rural Pennsylvania.

PARTICIPANTS: A total of 7,120 male (n = 3,312) and female (n = 3,808) community‐dwelling older adults enrolled in a Medicare managed‐risk contract.

MEASUREMENTS: All subjects completed a modified Level II Nutrition Risk Screen upon enrollment in the health plan. Height and weight were obtained by nursing personnel during an enrollment clinic visit. Subjects who reported 10 or more pounds weight loss in the previous 6 months were excluded. Logistic regression was used to evaluate the relationship between BMI and self‐reported functional limitation separately for each sex, adjusting for age, depression, and polypharmacy. Two schemes were used to categorize BMI: equally distributed sex‐specific quintiles and arbitrary division based on National Institutes of Health (NIH) Obesity Guidelines.

RESULTS: How BMI relates to functional limitation depends upon both sex and method of categorizing BMI. When BMI was considered in gender‐specific quintiles, women in the highest quintile of BMI had increased risk of functional impairment; there was no relationship between BMI and functional limitation for men. When BMI was categorized by the NIH obesity guidelines, both men and women with BMI> 40 had significantly increased risk of functional limitation.

CONCLUSIONS: The mechanisms behind gender discrepancy in self‐reported functional limitation remain unclear. Studies may need to consider men and women separately, because how BMI relates to function depends on gender. Further research is needed to evaluate how changes in weight and body composition during middle and old age affect functional status.
Preventing Falls in Older People: Impact of an Intervention to Reduce Environmental Hazards in the Home
Authors: Stevens Margaret , Holman C. D'Arcy J. , Bennett Nicole
Published: March 2003

OBJECTIVES: To evaluate the impact of an intervention to reduce fall hazards in the homes of older people.

DESIGN: The intervention was administered to the 570 subjects in the experimental arm of a randomized controlled trial, with follow‐up of subjects for 1 year.

SETTING: Community‐based seniors living in Perth, Australia.

PARTICIPANTS: People age 70 and older.

INTERVENTION: Registered nurses delivered the intervention. It consisted of a home hazard assessment, an educational strategy on general fall hazard reduction and ways to reduce identified home hazards, and the free installation of safety devices: grab rails, nonslip stripping on steps, and double‐sided tape for floor rugs and mats. All intervention subjects received the home hazard assessment, and 96% received the educational strategy. Grab rails were installed in 77% of homes, rugs were stabilized in 8%, and nonslip step stripping was installed in 36%.

MEASUREMENTS: Hazard prevalence was assessed at baseline in all homes and 11 months later in a random sample of 51 homes. Action taken in response to the intervention was assessed by a self‐completed postal questionnaire completed 11 months after the intervention.

RESULTS: All homes had at least one fall hazard. The most prevalent were floor rugs and mats (mean of 14 per home), stepovers (Stepovers are structural changes to the height of the floor that were designed to be stepped over rather than stepped upon, for example, the lip of a shower or a bath side.) (mean of seven per home), steps (mean of four per home), and trailing cords (mean of two per home).

CONCLUSIONS: Fall hazards are ubiquitous in the homes of older people. The intervention resulted in a small reduction in the mean number of hazards per house, with many study subjects taking action but removing only a few hazards. The impact of the intervention in achieving self‐reported action to reduce hazards was high.
Preventing Falls in Older People: Outcome Evaluation of a Randomized Controlled Trial
Authors: Stevens Margaret , Holman C. D'Arcy J. , Bennett Nicole , De Klerk Nick
Published: March 2003

OBJECTIVES: To evaluate the outcome of an intervention to reduce hazards in the home on the rate of falls in seniors.

DESIGN: Randomized controlled trial, with follow‐up of subjects for 1 year.

SETTING: Community‐based study in Perth, Western Australia.

PARTICIPANTS: People age 70 and older.

INTERVENTION: One thousand eight hundred seventy‐nine subjects were recruited and randomly allocated by household to the intervention and control groups in the ratio 1:2. Because of early withdrawals, 1,737 subjects commenced the study. All members of both groups received a single home visit from a research nurse. Intervention subjects (n = 570) were offered a home hazard assessment, information on hazard reduction, and the installation of safety devices, whereas control subjects (n = 1,167) received no safety devices or information on home hazard reduction.

MEASUREMENTS: Both groups recorded falls on a daily calendar. Reported falls were confirmed by a semistructured telephone interview and were assigned to one of three overlapping categories: all falls, falls inside the home, and falls involving environmental hazards in the home. Analysis was by multivariate modelling of rate ratios and odds ratios for falls, corrected for household clustering, using Poisson regression and logistic regression with robust variance estimation.

RESULTS: Overall, 86% of study subjects completed the 1 year of follow‐up. The intervention was not associated with any significant reduction in falls or fall‐related injuries. There was no significant reduction in the intervention group in the incidence rate of falls involving environmental hazards inside the home (adjusted rate ratio, 1.11; 95% CI = 0.82–1.50), or the proportion of the intervention group who fell because of hazards inside the home (adjusted odds ratio, 0.97; 95% CI = 0.74–1.28). No reduction was seen in the rate of all falls (adjusted rate ratio, 1.02; 95% CI = 0.83– 1.27) or the rate of falls inside the home (adjusted rate ratio, 1.17; 95% CI = 0.85–1.60). There was no significant reduction in the rate of injurious falls in intervention subjects (adjusted rate ratio, 0.92; 95% CI = 0.73–1.14).

CONCLUSIONS: The intervention failed to achieve a reduction in the occurrence of falls. This was most likely because the intervention strategies had a limited effect on the number of hazards in the homes of intervention subjects. The study provides evidence that a one‐time intervention program of education, hazard assessment, and home modification to reduce fall hazards in the homes of healthy older people is not an effective strategy for the prevention of falls in seniors.
The Impact of Insomnia on Cognitive Functioning in Older Adults
Authors: Cricco Meredith , Simonsick Eleanor M. , Foley Daniel J.
Published: March 2003

OBJECTIVES:

To examine whether self‐reported symptoms of insomnia independently increase risk of cognitive decline in older adults.

DESIGN:

Longitudinal cohort study.

SETTING:

The four sites of the Established Populations for Epidemiologic Studies of the Elderly.

PARTICIPANTS:

Six thousand four hundred forty‐four community‐dwelling men and women age 65 and older who had no more than one error on the Short Portable Mental Status Questionnaire (SPMSQ) at baseline and an in‐person interview at the third annual follow‐up (FU3).

MEASUREMENTS:

Insomnia was defined as report of trouble falling asleep or waking up too early most of the time. Cognitive decline was defined as two or more errors on the SPMSQ at FU3. Logistic regression was used to determine risk of cognitive decline associated with insomnia, controlling for demographic, behavioral, and health‐related factors. Analyses were stratified by sex and depressed mood.

RESULTS:

Among nondepressed men, those reporting symptoms of insomnia at both baseline and FU3 had an adjusted odds ratio (OR) of 1.49 (95% CI = 1.03–2.14) for cognitive decline, relative to those with no insomnia at FU3. Men with insomnia at FU3 only were not at increased risk (OR = 1.16, 95% CI = 0.82–1.65). These relationships were not found in women. Men and women with depressive symptoms at FU3 were at increased risk for cognitive decline independent of insomnia.

CONCLUSION:

Chronic insomnia independently predicts incident cognitive decline in older men. More sensitive measures of cognitive performance may identify more subtle declines and may confirm whether insomnia is associated with cognitive decline in women. J Am Geriatr Soc 49:1185–1189, 2001.
Impact of a New Assessment System, the MDS‐HC, on Function and Hospitalization of Homebound Older People: A Controlled Clinical Trial
Authors: Landi Francesco , Onder Graziano , Tua Ennio , Carrara Benigno , Zuccalá Giuseppe , Gambassi Giovanni , Carbonin PierUgo , Bernabei Roberto ,   on behalf of the Silvernet‐Hc Study Group of Bergamo
Published: March 2003

OBJECTIVES:

To evaluate the impact of a new assessment system, the Minimum Data Set for Home Care (MDS‐HC), on the functional status and hospitalization rates of frail, community‐dwelling older people.

DESIGN:

Single‐blind randomized trial with 1‐year follow‐up.

SETTING:

Bergamo, Italy.

PARTICIPANTS:

All 187 subjects who were eligible for home care services delivered by two Health Districts between September 1998 and April 1999.

INTERVENTION:

Random allocation to an intervention group undergoing MDS‐HC assessment or to a control group receiving conventional geriatric assessment with Barthel, Lawton and Brody, and Mini‐Mental State Examination (MMSE) scales.

MEASUREMENTS:

Hospitalization, health services use and costs, and variations in functional status.

RESULTS:

Survival analysis indicated that the intervention group was admitted to the hospital later and less often than were controls (relative risk = 0.49, 95% confidence interval = 0.56–0.97). Health services were used to the same extent, but intervention subjects used more in‐home help services. Total costs for the intervention group were 21% lower than for the control group. The adjusted mean scores of the activities of daily living index (51.7±36.1 vs 46.3±33.7; P = .05) and MMSE (19.9±8.9 vs 19.2±10.7; P = .03) were significantly improved in the intervention group as compared with the control group.

CONCLUSIONS:

The MDS‐HC assessment instrument may provide a cost‐saving approach to reducing institutionalization and functional decline in older people living in the community. J Am Geriatr Soc 49:1288–1293, 2001.
Health Care for Older Persons: A Country Profile—Lebanon
Authors: Abyad Abdulrazzak
Published: March 2003

Lebanon is a small country, comparable in size to New Hampshire. It is currently estimated that 8% of the population is age 65 and older. The Lebanese population has witnessed a clear demographic transition in the past few decades. Our culture demands respect for older people and values highly the natural bonds of affection between all members of the family. The healthcare system in the country is an adaptation of the European model. Despite the large number of physicians (approximately 10,000) there is a shortage of primary care and geriatric physicians. There are 36 nursing homes in Lebanon, with a total of 6,000 beds, but most of them are understaffed, with the exception of three nursing homes that offer relatively comprehensive services including rehabilitative, preventive, and curative services. The Ain Wizen Elderly Care Centre is well recognized for the program it operates for older people, which is a good model for the region and for Lebanon in terms of services, training, and research. Demographic changes and social and economic developments in Lebanon have created new realities in the unprecedented growth of the older population. Lebanon, like other developing countries, needs to define the policies and programs that will reduce the burden of an aging population on its society and economy. There is a need to ensure the availability of health and social services for older persons and to promote older persons' continuing participation in a socially and economically productive life.
Illness Representations According to Age and Effects on Health Behaviors Following Coronary Artery Bypass Graft Surgery
Authors: Gump Brooks B. , Matthews Karen A. , Scheier Michael F. , Schulz Richard , Bridges Michael W. , Magoverm George J.
Published: March 2003

OBJECTIVES: To determine if illness representations differ as a function of age and how these representations, in conjunction with age, predict postoperative health behaviors.

DESIGN: Prospective study of patients undergoing coronary artery bypass graft (CABG) surgery.

SETTING: A large metropolitan hospital providing regional cardiac care for patients in a tri‐state area, located in Pittsburgh, Pennsylvania.

PARTICIPANTS: All consenting patients (N = 309) from a consecutive series of patients scheduled for CABG surgery between January 1992 and January 1994. To be eligible for participation, patients could not be scheduled for any other coincidental surgery (e.g., valve replacement), and could not be in cardiac intensive care or experiencing angina at the time of the referral. Participants were predominantly male (70%) and married (80%), and averaged 62.8 years of age.

MEASUREMENTS: Postoperative self‐reported health behaviors.

RESULTS: Older participants awaiting CABG surgery were significantly more likely to believe old age to be the cause of their coronary heart disease (CHD) and significantly less likely to believe genetics, health‐damaging behaviors, health protective behaviors, and emotions to be the cause of their CHD than were younger participants awaiting surgery. Furthermore, the older participants were significantly more likely to believe they had no control over the disease and that the disease would be gone after surgery, and reported fewer postoperative health behavior changes than did younger participants.

CONCLUSION: These findings demonstrate significant differences in illness representations as a function of age. Furthermore, differences in postoperative health behaviors were consistent with differing illness representations.