bluuebunny/crossref_metadata_2025 huggingface dataset:
PHOTOAUTOTROPHIC GROWTH OF A RECENTLY ISOLATED N2‐FIXING MARINE NON‐HETEROCYSTOUS FILAMENTOUS CYANOBACTERIUM, SYMPLOCA SP. (CYANOBACTERIA)
Authors: Kumazawa Shuzo , Yumura Shin‐ichi , Yoshisuji Hidekazu
Published: March 2003

Photoautotrophic growth of a marine non‐heterocystous filamentous cyanobacterium, Symploca sp. strain S84, was examined under nitrate‐assimilating and N2‐fixing conditions. Under continuous light, photon flux density of 55 μmol photons·m−2 ·s−1 was at a saturating level for growth, and light did not inhibit the growth rate under N2‐fixing conditions even when the photon flux density was doubled (110 μmol photons·m−2  ·s−1). Doubling times of the N2‐fixing cultures under 55 and 110 μmol photons·m−2 ·s−1 were about 30 and 31 h, respectively. Under 110 μmol photons·m−2 ·s−1 during the light phase of an alternating 12:12‐h light:dark (L:D) cycle, the doubling time of the N2‐fixing culture was also about 30 h. When grown diazotrophically under a 12:12‐h L:D regime, C2H2 reduction activity was observed mainly during darkness. In continuous light, relatively large cyclic fluctuations in C2H2 reduction were observed during growth. The short‐term (<4 h) effect of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU; 5 μM) indicated that C2H2 reduction activity was not influenced by photosynthetic O2 evolution. Long‐term (24 h) effects of DCMU indicated that photosynthesis and C2H2 reduction activity occur simultaneously. These results indicate that strain S84 grows well under diazotrophic conditions when saturating light is supplied either continuously or under a 12:12‐h L:D diel light regime.
VALVE MORPHOGENESIS IN THE CENTRIC DIATOM PROBOSCIA ALATA SUNDSTROM1
Authors: Van De Meene Allison M. L. , Pickett‐Heaps Jeremy D.
Published: March 2003

Valve morphogenesis in Proboscia alata Sundstrom was followed in living cells and during treatment with antiactin and antimicrotubule drugs. Once cleaved, sibling cells rounded up and retracted. Soon, a granular organizing center (OC) appeared adjacent to the stub of the initiated valve. Silicification started within a silicon deposition vesicle (SDV) adjacent to the OC. The elongating valve was initially tubular and sealed at one end, creating the proboscis of the conical valve. The edge of the SDV and thinnest region of the forming valve was lined by a sleeve of bundled microtubules (MTs) that terminated short of the older more rigid part of the valve. The growing proboscis of living cells treated with the anti‐MT drug oryzalin became grossly distorted. EM revealed dense material lining the growing edge of the SDV; immunofluorescence microscopy showed a ring of actin here. Applied to living cells, the antiactin drug cytochalasin D caused the very young proboscis to collapse; in older valves, the base of the proboscis expanded. Thus, valve morphogenesis appeared controlled by the MT cytoskeleton, keeping the proboscis straight while actin molded its conical outline. At the tip of the proboscis was a slit resembling a labiate process. Its morphogenesis involved striated fibers and two MTs, reminiscent of the fibers and MTs associated with raphe morphogenesis. In contrast to spine‐like processes that elongate by tip growth, the tip of the proboscis was formed first, and the consequent “antitip growth” suggests the tip was originally the center of the valve face.
PHYTOPLANKTON PIGMENTS IN COASTAL LAKE MICHIGAN: DISTRIBUTIONS DURING THE SPRING ISOTHERMAL PERIOD AND RELATION WITH EPISODIC SEDIMENT RESUSPENSION1
Authors: Millie David F. , Fahnenstiel Gary L. , Carrick Hunter J. , Lohrenz Steven E. , Schofield Oscar M. E.
Published: March 2003

Phytoplankton pigment distributions during the spring isothermal periods of 1998 and 1999 and their association with episodic sediment resuspension were characterized in coastal waters of southern Lake Michigan. Total and phylogenetic group chl a concentrations (derived using chemical taxonomy matrix factorization of diagnostic carotenoids) corresponded with assemblage and group biovolumes estimated from microscopic enumeration (P≤ 0.001). Diatoms and cryptophytes dominated assemblages and together typically comprised greater than 85% of relative chl a. Total chl a concentrations and both fucoxanthin·chl a−1 and alloxanthin·chl a−1 ratios were similar across depths (P> 0.05), indicating uniform distributions of and photophysiological states for assemblages and diatoms and cryptophytes, respectively, throughout the mixed water column. Total chl a concentrations were not always spatially uniform from near‐shore to offshore waters, with the greatest variability reflecting the influence of tributary inflows upon coastal assemblages. Sediment resuspension strongly influenced water column particle density and light climate; however, total and group chl a concentrations did not correspond with coefficients of Kd and suspended particulate matter concentrations (P> 0.05). The correspondence of both light attenuation and suspended particulate matter concentration with relative diatom chl a (P≤ 0.001) indicated an apparent association between sediment resuspension and diatoms. This, and the negative association (P≤ 0.0001) between relative diatom and cryptophyte chl a, corresponded with the spatial dominance of diatom and cryptophyte chl a in near‐shore and offshore waters, respectively. The presence of viable chl a and fucoxanthin within the surficial sediment layer, established this layer as a potential source of meroplanktonic diatoms for near‐shore assemblages.
Development of Valves in the Marine Diatom Genus Trigonium
Authors: Tiffany M. A.
Published: March 2003

Trigonium arcticum and T. formosum, marine diatoms epiphytic on Ectocarpus sp., were collected from the sublittoral off Point Loma, California. Forming valves of these two sympatric species were studied using scanning electron microscopy. The earliest developing valve of T. arcticum encountered is a porous basal layer of silica, triangular, with pseudocelli just starting to form at each corner. The central annulus, the site of the earliest valve formation, appears to be about the size of a single areola. Early rimoportulae (labiate processes) are interspersed between central areolae and are simple oval openings. Internally these form their labiate lip‐like structures just before cribrum formation. Ridges form on the external side of the basal layer in a honeycomb pattern and produce the walls of the loculate structures. The ridges expand outward until cribrum formation is initiated. Small protuberances grow out from the edge of the ridge‐like structures and then become anvil‐shaped as they grow toward the center of the pores and form the ‘roofs’ of the loculi. In external view of the mature valve, the pores are smoothly covered over except for a ring of C‐shaped slits. These cribra are flush with the surface of the valve. At about the time the cribra are completing, rotae are formed within the porelli of the pseudocelli by extensions from two or three sides. The quadrangular T. formosum develops along much the same pattern. Differences are the less numerous, more centrally located rimoportulae, which possess external tubes and the formation of highly domed cribra.
Algal Polyunsaturated Fatty Acids: Food, Pheromones and Foul Odour
Authors: Watson S. , Janzen L.
Published: March 2003

Algal polyunsaturated fatty acids (PUFAs) are known to be high‐energy, often‐essential resources to freshwater aquatic food webs. On the other hand, high PUFA cell content in some algal taxa has been linked with the production of derivatives that may act as pheromones, allelogens or toxins. It has been known for some time that these compounds function in marine chemical ecology, but recent evidence indicates that they may play similar roles in freshwater ecosystems. This paper presents field and laboratory studies of planktonic and periphytic communities from freshwater systems, and shows that these communities are rich sources of certain PUFAs and derivatives which may function in both positive and negative foodweb interactions. This also has important implications for surface water quality, as these compounds are potent sources of rancid fishy odours.
The Use of Liquid Chromatography–Mass Spectrometry (LC–MS) in the Identification and Characterization of Mycosporine‐Like Amino Acids (MAAS)
Authors: Whitehead K. , Hedges J. I.
Published: March 2003

Mycosporine‐like amino acids (MAAs) are a class of UV‐absorbing compounds synthesized by a variety of marine and freshwater algae and cyanobacteria with absorption maxima between 310 and 360 nm. To date, ∼25 different MAAs have been characterized with several new compounds identified each year. A major difficulty in the analysis of MAAs is the lack of commercial standards. Thus far, MAAs have been identified by their retention time and UV absorption after separation via high performance liquid chromatography (HPLC). Complementing the HPLC method with the use of mass spectrometry (LC–MS) offers greater sensitivity and reduces the hindrance standard unavailability presents by providing detailed molecular information (molecular weight and fragmentation patterns). The molecular weight information adds one more level to our ability to characterize MAAs and any new UV‐absorbing compounds discovered. The fragmentation patterns obtained via LC–MS also contributes diagnostic information for structure elucidation and identification. LC–MS analysis has been used to examine UV‐absorbing compounds in methanolic extracts from Phaeocystis antarctica. When samples were analyzed using isocratic HPLC elution, several UV‐absorbing peaks were eluted. However, molecular weight and fragmentation patterns of some UV‐absorbing compounds were not commiserate with those expected for MAAs. Additionally, palythenic acid was detected rather than mycosporine‐glycine : valine as had been previously reported for this organism. Gradient elution provided further separation into MAA and ‘unknown’ groupings. The unknown UV‐absorbing component has longer retention times and different mass spectral characteristics with wavelength maxima between 315 and 325 nm. This study benefited immensely by the addition of MS techniques, as many of the compounds would have remained either misidentified or entirely unidentified. The increased analytical capability afforded by LC–MS allows us to further investigate the structural diversity and biochemistry of MAAs aiding our study of the role MAAs play as sunscreen agents.
Highlights of Recent Collections of Marine Algae from the Sultanate of Oman
Authors: Wynne M. J.
Published: March 2003

Collections of benthic marine algae made over the past 3 years on the Dhofar coast of the Sultanate of Oman have continued to provide a more complete picture of the floristic affinities of this up‐to‐now poorly explored region. This Algal Biodiversity Project of Oman was funded by the British Government's Darwin Initiative grant for the ‘Survival of Species’ and managed by HTS Development Ltd., of the UK. A rich and floristically complicated flora is emerging, with connections to subtropical and warm temperate regions. Many new algal taxa have been discovered and described, and numerous new records for Oman or for the Indian Ocean have been reported. Some species newly reported for Oman (and the Indian Ocean) had previously been known from Japan (Distromium decumbens, Kallymenia crassiuscula, Dudresnaya japonica, and Chondria crassicaulis). Sporochnus pedunculatus and Pedobesia simplex had been known from the North Atlantic and the Mediterranean and are new records for the Indian Ocean. Some new species of red algae have been described, such as a Dipterocladia and a Plocamium. Some brown algal novelties have also been discovered, including new species of Turbinaria and Jolyna, and a new genus of Chordariaceae. The macroalgal flora of southern Oman is rich with representatives of Codium, Scinaia, Galaxaura, Melanothamnus, and the families Gelidiaceae and Dictyotaceae. Several representative marine algae from southern Oman will be depicted and discussed.
Diversity of Fusiform Microchlorophyte Algae from Itasca State Park, Minnesota
Authors: Dimmer S. K. , Dean M. , Fawley M. W. , Fawley K. P.
Published: March 2003

Through the use of molecular techniques, several different types of fusiform and twisted‐fusiform microchlorophyte algae (Monoraphidium, Ankistrodesmus, etc.) have been characterized from samples taken from lakes and ponds of Itasca State Park, MN. PCR–RFLP analysis of 18S ribosomal RNA genes was used to categorize 29 different isolates from the Itasca State Park lakes into nine different types. The 18S ribosomal DNA sequences were determined for one isolate from each type for phylogenetic analysis. Light microscopy was used so that morphological characteristics as well as molecular characteristics can be compared and contrasted. The morphological characteristics were consistent for each PCR–RFLP type. Further discussion will include comparisons of the distribution and diversity of these organisms from Itasca State Park to those from Arrowwood National Wildlife Refuge, ND.
A Total Evidence Approach to Inferring the Phylogenetic Relationships within Aulacoseira (Bacillariophyta)
Authors: Edgar S. , Theriot E.
Published: March 2003

Phylogenies provide the context in which hypotheses about character evolution can be tested. But the phylogenetic understanding of many diatom taxa, including some of the more spatially and temporally ubiquitous genera, is insufficient to fruitfully pursue questions about character evolution within them. Consequently, we have estimated the phylogeny of Aulacoseira using a combination of nucleotide sequence data and data derived from morphological characteristics of the silica cell wall. In addition to the use of traditional ‘discrete’ or ‘qualitative’ morphological characters, we have assessed the use in our cladistic analyses of ‘continuous’ or ‘quantitative’ characters, including descriptors of the ontogenetic trajectories of these characters over a species' life cycle (size range). Also, molecular characters gathered from a chloroplast genome marker (rbcL) as well as a nuclear genome marker (18S rRNA) were used simultaneously in the cladistic estimation of the phylogeny of approximately 12 species of Aulacoseira. In order to have more thorough taxon sampling for a better estimate of phylogeny, we included several fossil species, as well as taxa where cultures were unavailable, by utilizing the morphologically based characters despite the absence of molecular characters for these taxa.
Phosphatase Expression by Chlorella Vulgaris (Chlorophyceae) is Mediated by Internal Phosphorus Levels and External pH
Authors: Evens T. J. , Koenig R.
Published: March 2003

Phosphorus has been implicated as one of the causative agents of the eutrophication of lacustrine, estuarine and coastal waters. One of the major inputs of phosphorus into these waters comes from agricultural nonpoint sources in the form of dissolved organic phosphorus (DOP). In order to better understand how DOP may directly impact the microalgal community structure, it is necessary to understand the physiology of DOP uptake and utilization. To this end, cultures of Chlorella vulgaris were grown in custom photobioreactors in acid (pH 5.5) and alkaline (pH 7.5) media under phosphate replete and starved conditions in order to determine the types and triggers of phosphatase expression by this organism. Analysis of differential phosphatase expression during phosphate stress indicates that cultures of C. vulgaris grown under alkaline conditions derepressibly express two alkaline phosphatases, while cultures grown under acid conditions weakly express only one alkaline phosphatase. Analysis of internal and external phosphorus levels, whole‐cell phosphatase activity and in‐gel activity of protein extracts indicate that alkaline phosphatase expression is further mediated by internal, as opposed to external, phosphorus levels.
Dinoflagellate Genomics: Results From an EST Approach
Authors: Bachvaroff T. R. , Herman E. M. , Delwiche C. F.
Published: March 2003

Dinoflagellates are enigmatic protists with odd nuclear features, interesting plastid gene arrangements and a proclivity for endosymbiotic relationships. Relatively little molecular work has been done on dinoflagellates, and only a handful of genes have been characterized in these organisms. We have begun an Expressed Sequenced Tag (EST) project with the aim of collecting plastid targeted but nuclear encoded genes from peridinin‐containing dinoflagellates. This provides an opportunity to understand the integration of endosymbiont genes into the host cell. Our sequencing effort has produced about 1000 unique ESTs from a Gonyaulax polyedra cDNA library obtained from David Morse. Of the 1535 total ESTs (72%, >400 bp), 466 sequences were identifiable by BLAST with a bit score above 50. The most abundant transcript is the peridinin–chlorophyll‐binding protein, which constituted 3% of the clones. More recently, we began sequencing from an Amphidinium carterae cDNA library made in our laboratory. This provides insight into expression patterns and is a resource for other workers in the field. Several clearly identifiable plastid genes have been found and preliminary analysis confirms the chromophyte, and therefore, tertiary origin of the peridinin plastid.
Spatial and Temporal Distribution of Life History Variants in the Red Alga, Mastocarpus Papillatus
Authors: Fierst J. L. , Kubler J. , Dudgeon S. R.
Published: March 2003

We investigated small‐scale spatial structure in Mastocarpus papillatus, a red alga with sexual and apomictic life‐history variants. Spatial structure and habitat partitioning can facilitate the coexistence of ecologically similar organisms, and in M. papillatus a large scale geographic spatial division is well documented. Variants of M. papillatus display geographic parthenogenesis where sexual fronds are common south of San Francisco Bay and apomicts dominate north of San Francisco Bay. Although geographic parthenogenesis in M. papillatus is well‐documented small‐scale spatial structure was not previously known due to the similar appearance of sexual and apomictic upright fronds. We investigated whether sexual and apomictic fronds differed in their spatial distribution by sampling for vertical differences in intertidal height and horizontal patchiness. Fronds were sampled when reproductive and cultured for life history. We found sexual variants were significantly aggregated at lower intertidal heights while apomicts were found throughout the intertidal range. Sexual fronds were strongly seasonal and reproduced October–December whereas apomictic fronds reproduced throughout the year. These results parallel the large‐scale geographic distribution with apomicts inhabiting marginal areas, and suggest dispersal capability may also facilitate geographic parthenogenesis.
Estimating Divergence Times within the Charophyta: A Bayesian Approach Using Fossil and DNA Sequence Data
Authors: Karol K. G. , McCourt R. M. , Delwiche C. F.
Published: March 2003

Morphological and molecular studies have advanced our understanding of charophycean green algal relationships. A recent multigene phylogenetic analysis has identified the Charales as the closest living relatives of land plants with the Coleochaetales sister to the Charales/land plant lineage. With a robust phylogeny now in hand, it is possible to explore phylogeny‐dependent questions that were previously difficult to assess. Estimating the divergence time of the land plant lineage is one such question. The most recent time estimate for the colonization of land by plants is 1061 ± 109 million years ago and 703 ± 45 million years ago for the divergence of vascular plants and bryophytes, a result much older than that found in the fossil record (roughly 470 million years ago). Several problems are inherent in estimating divergence times using DNA sequence data; these include the assumption of a molecular clock and choosing from a sparse fossil record for an external calibration date. Unlike most algae, a rich fossil record exists for the Charales in the form of calcified oospores termed gyrogonites. Representative gyrogonites that can be attributed to all six of the extant genera in the Characeae have been identified with reasonable accuracy. These six calibration points, identified from a closely related lineage of land plants, can be used in conjunction with a multigene DNA dataset to estimate the time that the land plant and Charales lineages diverged from their common ancestor.
UV‐Acclimation of Cultured Phytoplankton Exposed to Natural and Enhanced UVB Radiation and Methodological Aspects of MAA Quantification
Authors: Laurion I. , Roy S.
Published: March 2003

Bloom‐forming dinoflagellates often synthesize high concentrations of mycosporine‐like amino acids (MAAs) as a protection from high PAR and UV radiation, which may afford them a competitive advantage over other species. Photoprotection and long‐term acclimation to natural and enhanced UVB radiation were examined during 4 weeks in three dinoflagellates and one diatom. Semi‐continuous, nutrient‐replete cultures were maintained outdoors under natural light, with or without additional UVB (from lamps). The photosynthetic performance (XE‐PAM fluorometry) and the concentration and composition of MAAs and photoprotective carotenoids (PPCs; comprising xanthophylls) were followed weekly. A great variety of MAAs was found in the dinoflagellates (up to 10, identified by cochromatography and LC–MS). Large differences between sp. (and between two strains of the same sp.) were observed. In most cases, the composition and concentration of MAAs and PPCs increased under enhanced UVB. Growth rate and photosynthetic performance were sometime lower under enhanced UVB, while in other cases photoacclimation seemed to occur. The least affected sp. was Alexandrium tamarense who responded most rapidly to enhanced UVB. The algae also responded to changes in natural incident radiation. Some methodological aspects of MAA quantification were also investigated (with four species of dinoflagellates). Our results indicate how freezing (liquid‐N) likely breaks the cells, mobilizing the water‐soluble MAAs in the filter moist (otherwise highly packaged in fresh cells), while the organelles containing the pigments remain relatively intact. The implications of standard sample handling on the evaluation of MAA concentration in algae and on the estimation of the absorption of suspended material in water from in vivo spectroscopy (filter pad technique) will also be discussed.
The Transition From Algae to Embryophytes: Chloroplast Phylogenomic Evidence (II)
Authors: Lee J. , Manhart J. R.
Published: March 2003

The transition of plant life from aquatic algae to land plants was one of the major events in the history of life. However, in hypothesizing the evolutionary path of the transition, limited shared phenotypic characters in aquatic algae and land plants (embryophytes) have been a major hinderance. Chloroplast genomes contain characters useful in tracing evolutionary histories. Embryophyte chloroplast genomes are distinguished from algal cpDNAs by the presence of over 20 group II introns and three ribosomal protein operons (rpl23, clpP and 3Œrps12 operons). These phylogenomic features indicate a phylogenetic relationship of charophytes and embryophytes. In addition to these operons and introns, the evolution of rRNA and psbB operon evolution of streptophyte lineages will be incorporated with major biological phenotypic features to produce a phylogenetic tree. Basal embryophytes, the antithetic hypothesis, monophyly of embryophytes, and paraphyly of charophytes will be discussed. Strepotophytes are classified into three major groups (basal streptophytes, mid‐divergent streptophytes and late divergent charophytes‐embryophytes).
Physiological and Biochemical Responses of Two Seaweeds to Nutrient or Light Deprivation
Authors: Lourenço S. O. , Berges J. A.
Published: March 2003

The algae Fucus vesiculosus (brown) and Enteromorpha compressa (green) were cultured in long‐term experiments in which natural seawater without nutrient enrichment was used, or in which the plants were kept in complete darkness. Measurements of variable fluorescence (Fv/Fm), an indicator of photosynthetic competence, showed a gradual decrease of Fv/Fm in nutrient‐deprivation experiments, varying from 0.64 to 0.25 (E. compressa) and from 0.65 to 0.40 (F. vesiculosus) after 6 months of cultivation. F. vesiculosus was virtually unaffected after more than 2 months in darkness, showing values of Fv/Fm around 0.65 throughout the experiments, but cultures of E. compressa collapsed after 45 days in darkness. In both species lower concentrations of chlorophyll a resulted of nutrient‐deprivation experiments, decreasing three times in F. vesiculosus and 25 times in E. compressa by the end of the experiments. F. vesiculosus cultured in darkness showed 50% more chlorophyll a than the control, while plants of E. compressa kept in dark and in light showed similar values of chlorophyll a during the first 30 days of cultivation. The tissue‐N content of both species decreased dramatically in nutrient‐deprivation experiments, establishing variations in C : N ratio from 20 : 1 to 79 : 1 (F. vesiculosus) and from 8.6 : 1 to 75 : 1 (E. compressa). The algae showed small variations in C : N ratio throughout the experiments in darkness. Such as previously identified for phytoplanktonic species, the variations in the physiological responses exhibited by the seaweeds tested suggest that these conventional diagnostics of limitations may be misleading in natural algal assemblages, which are composed by mixed species. Gel electrophoretic is currently being performed to identify possible proteins that may respond specifically to these experimental conditions.
Distribution and Morphology of Diatoms in High Altitude Streams on Kauai (Hawaii)
Authors: Main S. P.
Published: March 2003

Diatom samples collected from Kawaikoi Stream differ in species composition and relative abundance from those in Kokee Stream. Kuwaikoi collects drainage from the Alakai Swamp, which developed on a 1200–1500 m elevation ridge of Mt. Waialeale extending at a right angle to the NE winds. Kokee lies about 2000 m further west at about 1100 m elevation. Frustulia and Eunotia species characteristic of low conductivity waters predominate. Greater diversity of Achnanthes, Navicula, Pinnularia and Surirella taxa occurs in the somewhat more conductive waters of Kokee. The morphological species observed bear a close, but not exact, resemblance to mainland taxa described in the literature. Morphological variations are documented using light and scanning electron microscopy.
Survival of Chlamydomonas Subsequent to Cryopreservation is Prevented by a Substance Released from Damaged Cells
Authors: Piasecki B. , Fan Yang , Diller K. R. , Brand J. J.
Published: March 2003

Storage of algae in liquid nitrogen offers a convenient way to permanently preserve many cultures with minimum genetic drift. We have successfully cryopreserved over 1400 strains in the Culture Collection of Algae at the University of Texas (UTEX), but over one‐fourth of UTEX cultures remain recalcitrant. Our previous studies demonstrate that unicellular algae frozen at a high cell density (>2000000 cells/mL) do not survive cryopreservation well. We now show that viability during cryopreservation of Chlamydomonas reinhardtii UTEX #89 at high cell densities is not affected by the physical proximity of cells. Instead, when cells are damaged, a small organic molecule(s) is produced and released into the medium preventing cryopreservation of other cells in the culture. Healthy C. reinhardtii cultures were treated with extracts prepared from damaged cells or culture medium separated from damaged cells, then cryopreserved by a standard method (Crutchfield et al. (1999) Eur J Phycol 34: 43–52). Viability was measured after thawing by the ability of a cell wall to preclude Evan's blue dye, and was confirmed by quantitative agar plating. The inhibitory substance from these fractions appears to affect living cells only during cryopreservation, but can be produced from cells by a variety of treatments. The inhibitor is heat‐stable, but heating cells to 80 °C precludes its production. The substance is stable when separated from cellular particulate matter, but gradually becomes inactive in the presence of cell membrane fractions. The inhibitor is a water‐soluble and heat‐stable organic compound(s), with a molecular mass less than or equal to 3500. Characterizing the inhibitory substance and the pathway that leads to its formation may explain why most multicellular algae remain recalcitrant to cryopreservation, and lead to protocols that allow the cryopreservation of a broader range of organisms.
Tracing Invasions of Caulerpa Taxifolia with Molecular Markers
Authors: Stam W. T. , Meusnier I. , Destombe C. , Valero M. , Olsen J. L.
Published: March 2003

Comparative sequence data from the rDNA ITS have proven very useful in species identification and identifying major biogeographic groups of Caulerpa taxifolia. However, the low variability of the sequence, and the need to screen hundreds of samples has limited its utility for population level studies. Here we report on the performance of two new markers suitable for population level screening: the chloroplast rDNA 16S intron‐2 and intersimple‐sequence‐repeat fingerprints (ISSRs). A new analysis of ITS1 insertion–deletion patterns was also conducted using all available sequences. A number of new insights have emerged. First, the invasive aquarium strain (Mediterranean, California) is clearly from Brisbane, but the Brisbane populations themselves may be the result of an introduction from Northern Australia. Second, an analysis of the new data in conjunction with an ITS1‐insertion–deletion analysis further suggests that the Mediterranean populations may be the result of not one, but two separate introductions. Third, intrapopulation genetic diversity between invasive Mediterranean and ‘native’ Australian populations revealed the occurrence of two divergent and widespread clades. The first clade grouped nontropical invasive populations with coastal inshore populations of Australia while the second clustered all offshore/oceanic populations so far studied. C. taxifolia, therefore exists as a complex of independent ecotypes that probably represent nascent species. Fourth, despite our finding of nine distinct nuclear and five distinct chloroplast profiles, strong linkage disequilibrium was found in most specimens, which indicates a predominance of asexual reproduction. However, nucleo‐cytoplasmic recombination was detected in one case, supporting hybridization both within and between populations.
Ultrastructure and Phylogeny of a New Species Belonging to the Prymnesiophyceae
Authors: Tanczos M. A. , Bailey J. C. , Andersen R. A.
Published: March 2003

Ultrastrucural and molecular data were used to examine a new alga (CCMP2000) collected from the Arabian Sea. Nonmotile vegetative cells are typically oblong to ovate, solitary and lack a gelatinous envelope. Ultrastructural analyses of these cells revealed the presence of a nucleus located in the posterior portion of the cell. A single large Golgi body with numerous cisternae is located anterior to the nucleus as are numerous profiles of mitochondria possessing tubular cristae. Two peripheral plastids are present having immersed pyrenoids that are traversed by one or more thylakoids. In some cells, the plastids are conspicuously lobed forming finger‐like extensions. Nonmotile vegetative cells possess reduced mature and immature flagella as well as a haptonema that are 1 micron long or less. A distinct internal covering and external wall surround the cell protoplasm. The outer wall is apparently composed of simple scales, but the composition (organic or mineralized?) of these scales is unknown. The outer wall may form a protuberance, or ‘foot’, at the posterior end of nonmotile cells. Interestingly, many vegetative cells are infected by a labyrinthulid. Flagellate stages have been observed and possess roughly equal length flagella and a haptonema. Phylogenetic analyses of nuclear 18S rRNA and plastid‐encoded rbcL genes indicate CCMP2000 is most closely related to Phaeocystis. However, CCMP2000 does not fit the description of Phaeocystis, and therefore, probably warrants recognition as a new taxon.
Aspiration Pneumonia: Dental and Oral Risk Factors in an Older Veteran Population
Authors: Terpenning Margaret S. , Taylor George W. , Lopatin Dennis E. , Kerr Connie Kinder , Dominguez B. Liza , Loesche Walter J.
Published: March 2003

OBJECTIVES: To investigate the importance of medical and dental factors in aspiration pneumonia in an older veteran population.

DESIGN: Prospective enrollment of subjects with retrospective analysis of data.

SETTING: Department of Veterans Affairs outpatient clinic, inpatient ward, and nursing home.

PARTICIPANTS: 358 veterans age 55 and older; 50 subjects with aspiration pneumonia.

MEASUREMENTS: Demographic and medical data; functional status; health‐related behaviors; dental care utilization; personal oral hygiene; comprehensive dental examination; salivary assays including IgA antibodies; and cultures of saliva, throat, and dental plaques.

RESULTS: Two logistic regression models produced estimates of significant risk factors. One model using dentate patients included: requiring help with feeding (odds ratio (OR) = 13.9), chronic obstructive pulmonary disease (COPD) (OR = 4.7), diabetes mellitus (OR = 3.5), number of decayed teeth (OR = 1.2), number of functional dental units (OR = 1.2), presence of important organisms for decay, Streptococcus sobrinus in saliva (OR = 6.2), and periodontal disease, Porphyromonous gingivalis in dental plaque (OR = 4.2), and Staphylococcus aureus presence in saliva (OR = 7.4). The second model, containing both dentate and edentulous patients included: requiring help with feeding (OR = 4.7), COPD (OR = 2.5), diabetes mellitus (OR = 1.7), and presence of S. aureus in saliva (OR = 8.3).

CONCLUSION: This study supports the significance of oral and dental factors while controlling for established medical risk factors in aspiration pneumonia incidence.
Prevalence of Tooth Loss and Dental Service Use in Older Mexican Americans
Authors: Randolph Whitney M. , Ostir Glenn V. , Markides Kyriakos S.
Published: March 2003

OBJECTIVES: To describe the prevalence of tooth loss, to examine risk factors for having fewer teeth or no teeth, and to describe the use of dental services in an older Mexican‐American population.

DESIGN: Data from the baseline phase of the Hispanic Established Population for the Epidemiological Study of the Elderly survey conducted from 1993 to 1994, a cross‐sectional survey of older Mexican Americans.

SETTING: Five southwestern states: Texas, California, Arizona, New Mexico, and Colorado.

PARTICIPANTS: 3,050 noninstitutionalized Mexican Americans age 65 to 99.

RESULTS: Twenty‐seven percent of the sample was completely edentulous and 22% reported visiting or speaking with a dental care professional in the preceding year. Logistic regression analyses showed that being older or being female was significantly associated with tooth loss, adjusting for education, income, smoking status, and diabetes mellitus. Current smokers (odds ratio (OR) = 1.69; 95% CI = 1.31–2.20) and diabetics (OR = 1.53; 95% CI = 1.27–1.84) were more at risk for tooth loss, as were persons of lower socioeconomic status.

CONCLUSIONS: The prevalence of tooth loss and use of dental services in this population of older Mexican Americans is lower than what has been previously found among older people in the general population.
Effects of Supporting Community‐Living Demented Patients and Their Caregivers: A Randomized Trial
Authors: Eloniemi‐Sulkava Ulla , Notkola Irma‐Leena , Hentinen Maija , Kivelä Sirkka‐Liisa , Sivenius Juhani , Sulkava Raimo
Published: March 2003

OBJECTIVES:

To determine whether community care of demented patients can be prolonged by means of a 2‐year support program based on nurse case management.

DESIGN:

Randomized controlled intervention study with 2‐year follow‐up.

SETTING:

Demented patients entitled to payments from the Social Insurance Institution for community care, in five municipalities in eastern Finland.

PARTICIPANTS:

One hundred demented patients, age 65 and older, living at home with the primary support of informal caregivers, allocated at random to the intervention (n = 53) or control group (n = 47).

INTERVENTION:

Intervention patients and their caregivers were provided with a 2‐year intervention program of systematic, comprehensive support by a dementia family care coordinator.

MEASUREMENTS:

Time to institutionalization (period in community care) from enrollment of patients in the study to their placement in long‐term institutional care.

RESULTS:

During the first months, the rate of institutionalization was significantly lower in the intervention group than in the control group (P = .042), but the benefit of the intervention decreased with time (P = .028). Estimated probability of staying in community care up to 6, 12, and 24 months was 0.98, 0.92, and 0.63 in the intervention group and 0.91, 0.81, and 0.68 in the control group, respectively. Results also suggest that the intervention used in the study might be especially beneficial to patients with severe dementia and those with problems threatening the continuity of community care.

CONCLUSIONS:

The placement of demented patients in long‐term institutional care can be deferred with the support of a dementia family care coordinator. However, by the end of the 2‐year intervention, the number of patients institutionalized was similar in the intervention and control group. It seems to be beneficial to direct this type of intensive support at severely demented patients and their caregivers. On the basis of our experiences, we suggest that intervention by a dementia family care coordinator should be targeted especially at patients with problems threatening the continuity of community care. J Am Geriatr Soc 49:1282–1287, 2001.
Highlights of Papers in Clinical Investigations Section: Colonization of Skilled‐Care‐Facility Residents with Antimicrobial‐Resistant Pathogens
Authors: Trick WE , Weinstein RA , DeMarais PL
Published: March 2003

The frequency of colonization of skilled‐care‐unit residents by several antimicrobial‐resistant bacterial species was determined in 117 participants. A total of 50 (43%) residents were culture positive for one or more antimicrobial‐resistant pathogens, with 13 (26%) being colonized by more than one resistant species. Only three residents were on contact‐isolation precautions. Colonization of skilled‐care‐unit residents by antimicrobial‐resistant pathogens is common and infection control strategies that are effective and feasible in long‐term care settings are needed.
Use of Anticholinergic Medications by Older Adults with Dementia
Authors: Roe Catherine M. , Anderson Michael J. , Spivack Barney
Published: March 2003

OBJECTIVES: To compare the prevalence of anticholinergic use in older adults with probable dementia with that of a matched comparison group of older adults who were unlikely to have dementia and to examine the extent to which patients taking donepezil concomitantly use anticholinergic medications.

DESIGN: Retrospective study.

SETTING: Community‐based older adults receiving medications through a pharmacy benefit management company.

PARTICIPANTS: Eight hundred thirty‐six patients aged 65 and older. Patients taking donepezil (n = 418) constituted the treatment group. Patients not taking donepezil (n = 418) constituted the comparison group. Each treatment group member was matched with a comparison group member on the basis of age, sex, and number of drugs taken for chronic conditions.

MEASUREMENTS: The prevalence of anticholinergic use was compared in the treatment and comparison groups over a 3‐ to 12‐month follow‐up period using pharmacy claims data. The proportion of follow‐up period days that treatment group members concomitantly used donepezil and anticholinergics was also examined.

RESULTS: Older adults with probable dementia were more likely to use anticholinergics than matched comparison group patients (33.0% vs 23.4%; P = .001). Of treatment group members receiving anticholinergics, 26.1% used multiple anticholinergic medications. Treatment group members who received anticholinergics used those drugs concomitantly with donepezil on a mean of 28.4% of follow‐up period days.

CONCLUSIONS: Community‐based, commercially insured, older adults with probable dementia are more likely to take anticholinergics than matched controls. Patients taking donepezil frequently use an anticholinergic medication concomitantly. This study suggests that prescribing for older adults with dementia could be improved, especially if cognitive enhancing agents are being considered.
Deciding on Anticoagulating the Oldest Old with Atrial Fibrillation: Insights from Cost‐Effectiveness Analysis
Authors: Desbiens Norman A.
Published: March 2003

OBJECTIVES: To better understand the tradeoffs between the efficacy of anticoagulation with warfarin and its side effects in the oldest old with nonrheumatic atrial fibrillation (AF).

DESIGN: Cost‐effectiveness analysis.

SETTING: Published literature, including meta‐analyses when available, and web‐based sources.

PARTICIPANTS: Those aged 65 to 100 with AF.

INTERVENTION: Anticoagulation with warfarin.

MEASUREMENTS: Quality‐adjusted life expectancy and cost.

RESULTS: Anticoagulation is not effective in persons with AF who do not have other risk factors, even in the oldest old. The best argument for its use (prolongation of life at an acceptable cost) can be made in those at major risk for stroke because of previous stroke or transient ischemic attack, diabetes mellitus, and hypertension, but poor quality of life before anticoagulation and comorbidities that carry their own risks of dying diminish benefits.

The decision to anticoagulate the oldest old with AF must take into consideration the risk of hemorrhagic stroke and of death from hemorrhagic stroke that existed before anticoagulation, the increased risk of hemorrhagic stroke and of death from hemorrhagic stroke while anticoagulated, and the efficacy of anticoagulation. Cost‐effectiveness is also influenced by the cost of warfarin, the risk of major extracranial bleeding, the risk (natural and anticoagulated) of death from hemorrhagic stroke, the rate of ischemic stroke, the cost of major extracranial bleeding and hemorrhagic strokes, the cost of nursing home care, and the fraction of patients with stroke who need nursing home care.

CONCLUSION: There is no compelling evidence to date that anticoagulation prolongs quality‐adjusted life expectancy in the oldest old with nonrheumatic AF. More studies that better estimate the risk of intracranial bleeding with and without anticoagulation in the oldest old are needed before recommendations can be made. The oldest old who are most likely to benefit are those who have a high risk of stroke secondary to risk factors other than age alone, although quality of life and life expectancy related to these risk factors limit obtained benefit. Recommendations that all older persons with AF should be anticoagulated are premature.
Predicting Cognitive Impairment in High‐Functioning Community‐Dwelling Older Persons: MacArthur Studies of Successful Aging
Authors: Chodosh Joshua , Reuben David B. , Albert Marilyn S. , Seeman Teresa E.
Published: March 2003

OBJECTIVES: To examine whether simple cognitive tests, when applied to cognitively intact older persons, are useful predictors of cognitive impairment 7 years later.

DESIGN: Cohort study.

SETTING: Durham, North Carolina; East Boston, Massachusetts; and New Haven, Connecticut, areas that are part of the National Institute on Aging Established Populations for Epidemiological Studies of the Elderly.

PARTICIPANTS: Participants, aged 70 to 79, from three community‐based studies, who were in the top third of this age group, based on physical and cognitive functional status.

MEASUREMENTS: New onset of cognitive impairment as defined by a score of less than 7 on the Short Portable Mental Status Questionnaire (SPMSQ) in 1995.

RESULTS: At 7 years, 21.8% (149 of 684 subjects) scored lower than 7 on the SPMSQ. Using multivariate logistic regression, three baseline (1988) cognitive tests predicted impairment in 1995. These included two simple tests of delayed recall—the ability to remember up to six items from a short story and up to 18 words from recall of Boston Naming Test items. For each story item missed, the adjusted odds ratio (AOR) for cognitive impairment was 1.44 (95% confidence interval (CI) = 1.16–1.78, P < .001). For each missed item from the word list, the AOR was 1.20 (95% CI = 1.09–1.31, P < .001). The Delayed Recognition Span, which assesses nonverbal memory, also predicted cognitive impairment, albeit less strongly (odds ratio = 1.06 per each missed answer, 95% CI = 1.003–1.13, P = .04).

CONCLUSIONS: This study identifies measures of delayed recall and recognition as significant early predictors of subsequent cognitive decline in high‐functioning older persons. Future efforts to identify those at greatest risk of cognitive impairment may benefit by including these measures.
Screening for Alzheimer's Disease: The Memory Impairment Screen Versus the Conventional Three‐Word Memory Test
Authors: Kuslansky Gail , Buschke Herman , Katz Mindy , Sliwinski Martin , Lipton Richard B.
Published: March 2003

OBJECTIVES:To improve screening for Alzheimer's disease (AD) with the Memory Impairment Screen (MIS), a 4‐minute, four‐item delayed free and cued recall memory test with controlled learning and high discriminative validity. To assess the discriminative validity of the MIS for AD and to compare it with the conventional three‐word memory test, a delayed free recall task, widely recommended as a dementia‐screening test in clinical practice.

DESIGN:Cross‐sectional validation study nested within a longitudinal study of aging and dementia. The MIS and the standard three‐word memory task were administered as part of a comprehensive neurological and neuropsychological evaluation.

SETTING:Einstein Aging Study at the Albert Einstein College of Medicine, Bronx, New York.

PARTICIPANTS:Two hundred forty community‐dwelling older adults.

MEASUREMENTS:Sensitivity, specificity, and positive predictive value (PPV) were calculated for the MIS and three‐word memory test as screening tests for AD.

RESULTS:In comparison with the three‐word memory task, the MIS had higher sensitivity (.86 vs .65), higher specificity (.97 vs .85), and greater PPV (.80 vs .37) as a screen for AD.

CONCLUSIONS:The MIS had high discriminative validity as a screening test for AD and substantially outperformed the three‐word memory task. Given its validity and brevity, the MIS has important advantages as an AD screen for use in primary care.