bluuebunny/crossref_metadata_2025_split huggingface dataset:
GROWTH RATES AND ULTRASTRUCTURE OF SILICEOUS SETAE OF CHAETOCEROS GRACILIS (BACILLARIOPHYCEAE) 12
Authors: Rogerson A. , DeFreitas A. S. W. , McInnes A. G. 
Published: March 2008

ABSTRACT The growth of setae in post‐division Chaeloceros gracilis Schütt was triphasic. Following cell separation there was an initial lag phase of about 30 min after which setae grew linearly at rates ranging from 0.20 to 0.38 μm‐min−1. The growth rate was independent of whether diatoms cultured in medium containing 200 μM Si were transferred for experimentation to media containing 10 or 200 μM Si. When developing setae had attained a length of approximately 2 μm, their growth rate slowed as they entered a clearly defined plateau phase. The amount of silicon per unit length of setae was found to be 0.02 pg Si μm−1, and the deposition rate was estimated as 0.005 Pg Si min−1. Transmission electron microscopy revealed an axial structure resembling a microlubule extending the length of each seta and membrane bound polyphosphate bodies postulated to be the energy source for growth and associated biomineralization processes.
A DESCRIPTIVE AND ULTRASTRUCTURAL STUDY OF THE GREEN ALGA, CHLAMYDOMONAS DESMIDII SP. NOV. (VOLVOCALES. CHLAMYDOMONADACEAE) FROM ROCKY MOUNTAIN NATIONAL PARK LAKES 1
Authors: Kugrens Paul , Delivopoulos Stylianos G. 
Published: March 2008

ABSTRACT The green algal flagellate Chlamydomonas desmidii sp. nov., is described from several lakes in Rocky Mountain National Park, Colorado. The biflagellate cells generally have an hour‐glass shape. They possess a single chloroplast with two pyrenoids and a superficial stigma near the center of the cell. Numerous contractile vacuoles occur in the Peripheral cytoplasm and they are arranged in several rings around the nucleus in the constricted region of the cell. Ultrastructural studies verify these features and elaborate upon the structure of the cell.
TWO NEW PLOCENE SPECIES OF CYCLOSTEPHANOS (BACILLARIOPHYCEAE) WITH COMMENTS ON THE CLASSIFICATION OF THE FRESHWATER THALASSIOSIRACEAE1
Authors: Theriot Edward , Kociolek John P. 
Published: March 2008

ABSTRACTTwo new species of the diatom genus Cyclostephanos Round are described from Pliocene fossil deposits in western North America. Cyclostephanos undatus is distinguished from other Cyclostephanos species by its tangentially undulate valve face; Cyclostephanos fenestratus is distinguished by its extremely shallow alveoli. This paper records previously unreported morphological detail of Cyclostephanos and speculates that structure of the punctum, labiate process and strutted process may enhance diagnosis of the freshwater genera of the Thalassiosiraceae Lebour emend. Hasle. Cyclostephanos undatus is similar to several Cyclotella species, but its external costae are raised and its alveolar morphology is similar to that of Cyclostephanos dubius (Fricke) Round. Cyclostephanos fenestratus is similar in external view to Stephanodiscus Ehrenb. However, the two species described here have flat cribra covering the mantle puncta and the labiate processes appear to lack external tubes, whereas Stephanodiscus species have domed mantle cribra and external tubes.
SEASONAL ANALYSIS OF VOLATILE ORGANIC BIOGENIC SUBSTANCES (VOBS) IN FRESHWATER PHYTOPLANKTON POPULATIONS DOMINATED BY DINOBRYON, MICROCYSTIS AND APHANIZOMENON1
Authors: Jüttner Friedrich , Höflacher Brigitte , Wurster Karl 
Published: March 2008

ABSTRACTOver the course of one year the volatile organic biogenic substances (VOBS) found in the water of a eutrophied shallow lake were determined by gas chromatographic and mass spectrometric methods. The substances detected belonged to nor‐carotenoids, terpenoids, unsaturated hydrocarbons, ketones, and aldehydes. The occurrence of particular VOBS correlated with the frequency with which certain phytoplankton species were recorded. The latter showed a well developed succession in that year. The following correspondences were found: β‐cyclocitral and Microcystis; heptadec‐cis 5‐ene and Oscillatoria redekei; geosmin and argosmin and Aphanizomenon gracile; hepta‐trans, cis 2,4‐dienal, deca‐trans, cis 2,4‐dienal and Dinobryon; octa‐trans, cis 1,3,5‐triene and Asterionella formosa. Dictyopterenes and ectocarpene were only detected in high amounts in one sample obtained in August. The VOBS exhibited marked dynamics in the lake and usually were rapidly eliminated from the water body.
PROTOPLAST ISOLATION AND CELL DIVISION IN THE AGAR‐PRODUCING SEAWEED GRACILARIA (RHODOPHYTA)1
Authors: Cheney Donald P. , Mar Emily , Saga Naotsune , van der Meer John 
Published: March 2008

ABSTRACTMethods were developed for the isolation of large numbers of healthy protoplasts from two species of the agarophyte Gracilaria; G. tikvahiae McLachlan and G. lemaneiformis (Bory) Weber‐van Bosse. This is the first report of protoplast isolation and cell division in a commercially important, phycocolloid‐producing red seaweed, as well as for a member of the Florideophycidae. The optimal enzyme composition for cell wall digestion and protoplast viability consisted of 3% Onozuka R‐10, 3% Macerozyme R‐10, 1% agarase and 0.5% Pectolyase Y‐ 23 dissolved in a 60% seawater osmoticum containing 1.0 M mannitol. The complete removal of the cell wall was confirmed by several different methods, including electron microscopic examination, and the absence of Calcofluor White (for cellulose) and TBO (for sulfated polysaccharide) staining. Spontaneous protoplast fusion was observed on several occasions. Protoplast viability was dependent upon the strain and age of the parent material, as well as the mannitol concentration of the enzyme osmoticum. Cell wall regeneration generally occurred in 2‐6 days; cell division in 5‐10 days. Protoplast‐produced cell masses up to the 16‐32 cell stage have been grown in culture. However, efforts to regenerate whole plants have been unsuccessful to date.
FRUSTULAR MORPHOLOGY AND TAXONOMIC AFFINITIES OF NAVICULA COMPLANATOIDES (BACILLARIOPHYCEAE)1
Authors: Brogan Michael W. , Rosowski James R. 
Published: March 2008

ABSTRACTLive and prepared cells of the marine pennate diatom Navicula complanatoides Hust. were examined with light and electron microscopy. It has narrowly lanceolate valves (26–55 μm long, 4–5 μm wide) and girdles 10–24 μm in depth. Striae are parallel at the center of the valve (24–28 in 10 μm), becoming slightly convergent toward the apices.Electron microscopy revealed that the external valve surface presents a longitudinally ribbed appearance (20–28 parallel ribs at its maximum width), whereas internally, rectangular areolae are occluded by ricae. The raphe slit lies in a narrow axial area, and one side of the raphe sternum is deeper and folds over the other, obscuring the internal opening. Internally, the central virga on one side of the raphe and two virgae on the other are somewhat broader. A conspicuous pore (stigma) is present between the two broadened virgae.The girdle consists of valvocopulae, copulae, and pleurae. There are 16–20 bands per cingulum. The valvocopulae and copulae are hollow tube‐like structures, with inner and outer portions contrsting in morphology. They decrease in diameter in an abvalvar direction. There are four pleurae. These are flat bands which facilitate overlap of the epicingulum and hypocingulum.Fundamental features of the valve and girdle reveal the distinctness of this species within Navicula. The areolae, external longitudinal ribs, and raphe structure suggest affinities with Pleurosigma, Gyrosigma, and Haslea. It is hypothesized that they share a derived state which indicates a recent common ancestor for these taxa. N. complanatoides and related species of the Naviculae microstigmatacae are distinctive enough to merit their own genus within the Naviculaceae.
PROPERTIES OF MICROCYSTIS AERUGINOSA AND M. FLOS‐AQUAE (CYANOPHYTA) IN CULTURE: TAXONOMIC IMPLICATIONS1
Authors: Doers Mary P. , Parker Dorothy L. 
Published: March 2008

ABSTRACTCultures were cloned from a sample containing Microcystis aeruginosa, M. flos‐aquae and a few morphological intermediates. The M. aeruginosa cultures remained distinct from the M. flos‐aquae cultures in (a) cell size, (b) cell aggregation pattern, (c) width of the mucilage surrounding the multicellular colonies, (d) sharpness of the mucilage boundary, (e) efect of 0.1–1.0 μM calcium chloride on the disaggregation of multicellular colonies, (f) frequency of mucilage mutants and (g) colony morphology on agar media. No M. flos‐aquae culture produced morphs resembling M. aeruginosa, inconsistent with proposals that M. flos‐aquae is a developmental stage or environmentally‐induced variant of M. aeruginosa. After longterm cultivation, but not soon after origanal isolation, several M. aeruginosa cultures contained mutants with diminished mucilage production and an altered colony shape.
LIPIDS AND CHEMOTAXONOMY OF PROCHLOROTHRIX HOLLANDICA, A PLANKTONIC PROKARYOTE CONTAINING CHLOROPHYLLS a AND b1
Authors: Volkman John K. , Burger‐Wiersma Tineke , Nichols Peter D. , Summons Roger E. 
Published: March 2008

ABSTRACTSThe lipid composition of a planktonic prokaryote, Prochlorothrix hollandica Burger‐Wiersma, isolated from Lake Loosdrecht (The Netherlands) has been determined. This species is only the second prokaryote that has been found to contain chlorophylls a and b. Its lipid composition is similar to that of another prochlorophyte, Prochloron didemni Lewin, as well as to some cyanobacteria and bacteria, but there are also some unique features. Major fatty acids were 14:0, 14: 1ω5, 16:0, 16: 1ω7 and two novel fatty acids 16: 1ω12 (hexadec‐4‐enoic acid) and a new 16:2 isomer. Double bond positions in monounsaturated fatty acids and alkenes were determined by derivatization with dimethyl disulfide followed by analysis of the products by gas chromatography‐mass spectrometry. Hydrocarbons consisted mainly of the pentacyclic triterpene hop‐22(29)‐ene and straight‐chain n‐heptadecane and n‐heptadec‐5‐ene. The presence of hopanoids, low abundance of triacylglycerols and absence of sterols clearly show that the lipid biochemistry of this organism is more closely related to that of prokaryotes than to eukaryotes even though it contains chlorophyll b which is more typical of green algae. Implications of these data to chemotaxonomic studies of this unusual group of prokaryotes are discussed.
GLYOXYLATE CYCLE ENZYME ACTIVITIES IN THE CYANOBACTERIUM ANACYSTIS NIDULANS1
Authors: Eley James H. 
Published: March 2008

ABSTRACTThe enzymes of the glyoxylate cycle, isocitrate lyase (EC.4.1.3.1) and malate synthase (EC.4.1.3.2), were measured in cell‐free extracts from the cyanobacterium Anacystis nidulans Drouet during photoautotrophic growth in medium aerated with ordinary air (0.03% CO2). Isocitrate lyase had an average specific activity of 112 nmoles·min−1·mg protein−1 whereas malate synthase had an average specific activity of 12.5 nmoles·min−1·mg protein−1. Unpurified isocitrate lyase showed classical Michaelis kinetics with a Km of 8 mM. Isocitrate lyase activity was strongly inhibited by numerous cellular metabolites at 10 mM concentration. The previously reported low specific activity for isocitrate lyase may be due to metabolite inhibition caused by growth in high CO2 concentrations. The activities reported for isocitrate lyase and malate synthase suggest the operation of the glyoxylate cycle in Anacystis nidulans under CO2‐limiting growth conditions.
COMPETITION FOR PHOSPHORUS BETWEEN DESMIDS1
Authors: Healey F. Patrick , Hendzel Leonard L. 
Published: March 2008

ABSTRACTDuring competition for phosphate in continuous cultures, Cosmarium subcostatum Nord. routinely displaced Staurastrum paradoxum Meyer. The rate of displacement was independent of cell density between 100 and 6000 cells mL−1. This suggests that competition for nutrients is important over a wide range of naturally occurring cell densities. C. subcostatum had higher saturated rates of phosphate uptake but also higher half saturation values for uptake. As a result, the two desmids were similarly able to take up phosphate at low concentrations. The competitive advantage of C. subcostatum lay in its greater yield per unit of phosphorus. Growth of the two algae in shared medium in a dual‐chamber chemostat had no effect on uptake or yield characteristics.
REPEAT AND SINGLE COPY SEQUENCES ARE DIFFERENTIALLY CONSERVED IN THE EVOLUTION OF KELP CHLOROPLAST DNA1
Authors: Fain Steven R. , Druehl Louis D. , Baillie David L. 
Published: March 2008

ABSTRACTA method for the isolation of total blade, chloroplast and nuclear DNAs from kelp is described. Total blade DNA was isolated from various kelp species at yields of about 1.0 μg.g−1 wet weight of tissue extracted. Purified chloroplast and nuclear DNAs were isolated from Macrocystis integrifolia at respective yields of about 0.05 μg.g−1 and 1.0 μg.g−1 wet weight of tissue extracted.Hybridization experiments with a cloned portion of the 23S rRNA gene of M. integrifolia as probe (pMiR23S) showed that the M. integrifolia chloroplast genome contains two copies of the 23S rRNA gene.Three regions of the kelp chloroplast genome were studied by restriction analysis of the cpDNA of five genera. Respective differences were assessed by comparing the restriction fragment patterns produced with five restriction endonucleases for each of three cloned M. integrifolia cpDNA hybridization probes. The kelp cpDNA sequences that hybridized to the repeated sequence probe pMiR23S were less divergent (100 × p = 2.53) than were the sequences that hybridized to the single copy probes pMiR432 and pMiH7 (100 × p = 7.48–7.74). Sequence variation (100 × p) between kelp species ranged from 3.38–6.82. Sequence variation between kelp species and Fucus gardneri ranged from 9.08–12.04.Chloroplast DNA restriction fragment length data were used to derive two most parsimonious phylogenetic trees. Both trees had consistency indexes of 0.78 and indicated that the three lessoniacean genera in the comparison do not comprise a single distinct lineage.
THE USE OF PLASTID DNA RESTRICTION ENDONUCLEASE PATTERNS IN DELINEATING RED ALGAL SPECIES AND POPULATIONS1
Authors: Goff Lynda J. , Coleman Annette W. 
Published: March 2008

ABSTRACTPlastid DNA band patterns generated by electrophoresis of endonuclease digests demonstrate remarkable conservation of DNA sequences at the species and subspecies level in flowering plants. Generally, patterns are identical or near‐identical from different populations belonging to the same species. This methodology has now been applied to red algae to ascertain its value in systematic studies.Plastid DNA from nine bangiophycean and florideophycean red algae was isolated and cut with restriction endonucleases that recognize different 6‐base pair sequences. The patterns generated upon the electrophoretic separation of digestion fragments show that within a species patterns are identical, but not within higher taxa. The proper identification of one Gracilaria population of uncertain taxonomic affinity was clearly established by this method of plastid DNA analysis.Differences between species in plastid DNA sequences were confirmed by probing blots of restriction fragments with known gene sequences. A number of heterologous plastid DNA probes were found to be sufficiently homologous to be useful in studying red algal DNA.Unexpectedly, supercoiled circular plasmids ranging in size from ca. 1.5–8 kb were found in some red algal species but not in others. The position of these plasmids in agarose gels following electrophoresis is uniform within a species but differs between different species of the same genus, contributing further patterns for taxonomic analysis.
Is Pregnancy the Time to Change Alcohol Consumption Habits in France?
Authors: De Chazeron Ingrid , Llorca Pierre‐Michel , Ughetto Sylvie , Vendittelli Françoise , Boussiron Didier , Sapin Vincent , Coudore François , Lemery Didier 
Published: March 2008

Background:  Although it is well known that France has a cultural history of alcohol use, no recent French data on alcohol consumption during pregnancy in a large sample are available.Methods:  To determine the alcohol consumption patterns among pregnant women in France, we analyzed data from a 1‐year multicenter self‐survey. Sociodemographic profile, obstetrical history, neonatal data, and a self‐report for assessing drinking patterns during pregnancy including AUDIT were recorded from women who delivered recently. Cases of fetal alcohol syndrome (FAS) were also reported.Results:  A total of 837 pregnant women have described all parameters. The mean age at delivery of our sample was 29.7 years (SD = 4.8 years). A total of 52.2% of women indicated that they had consumed alcohol at least once during their pregnancy, and among abstainers 54.5% had a positive AUDIT score. Of the pregnant women who consumed alcohol, 13.7% reported at least one binge drinking episode (5 or more drinks on 1 occasion) during pregnancy. Binge drinking is significantly more frequent than regular alcohol consumption (at least 1 drink more than 1 time per week) during pregnancy. A prevalence rate of FAS of 1.8 per 1,000 live births was observed.Conclusions:  There is a large population of women who still drink alcohol during pregnancy, particularly in binge drinking episodes. This underlines the need to clearly inform women of childbearing age about the dangers of alcohol during pregnancy as related to all types of consumption. Moreover, acting to prevent alcohol consumption prior to pregnancy may also greatly influence prenatal drinking.
Impulsive Errors on a Go‐NoGo Reaction Time Task: Disinhibitory Traits in Relation to a Family History of Alcoholism
Authors: Saunders Buddy , Farag Noha , Vincent Andrea S. , Collins Frank L. , Sorocco Kristen H. , Lovallo William R. 
Published: March 2008

Background:  Behavioral undercontrol may contribute to risk for alcoholism in vulnerable persons. We predicted that healthy young adults with a family history of alcoholism (FH+) who also displayed externalizing behavior characteristics (low scores on the California Psychological Inventory Sociability Scale; CPI‐So) would exhibit more impulsive responding (false alarms) on a Go‐NoGo reaction time task.Methods:  Subjects were 230 healthy volunteers, 18 to 30 years of age with no history of alcohol or drug dependence. The task included 100 trials: 60 of “Go,” calling for a button press, and 40 of “NoGo,” or “XX,” calling for inhibiting a response. Data analysis involved a signal detection analysis of performance with subsequent group comparisons for rates of impulsive responding indicated by False Alarms (responses to NoGo signals).Results:  CPI‐So scores were lower in FH+ than in FH– (p < .000001) indicating a greater clustering of disinhibitory tendencies in these persons. FH, CPI‐So scores, and Gender together predicted false alarm rates, accounting for 4.9% of the variance, F = 3.89, p = 0.009. False alarms were associated with low CPI‐So scores, F = 5.15, p = 0.024, and being male, F = 6.27, p = 0.013, but not with FH once these variables were accounted for.Conclusions:  A disinhibited temperament may underlie a behavioral impulsivity that contributes to elevated risk for future alcoholism, especially among FH+ males.
Managing Interdependence: The Effects of Outsourcing Structure on the Performance of Complex Projects*
Authors: Hui Pamsy P. , Davis‐Blake Alison , Broschak Joseph P. 
Published: March 2008

ABSTRACTThe outsourcing of complex activities has become a common organizational practice. Yet very little research has focused on the implications of how these activities are divided up among outsourcing partners. Drawing on structural contingency theory, we argue that: (1) because activities within stages of complex projects are highly interdependent, outsourcing structures where owner firms do not maintain high levels of dominance over the activities that are performed will pose control and coordination challenges, leading to poor project performance; (2) the adverse effects of poorly structured outsourcing arrangements will spill over to subsequent project stages when activities are interdependent across project stages; and (3) dividing activities among large numbers of contractors or distributing work evenly among contractors exacerbates coordination and control problems further contributing to poor project performance. Our empirical analysis of 323 capital facility construction projects supports our predictions. Overall, these results provide strong evidence that some outsourcing structures are more costly than others and that because of the nature of complex projects the detrimental effects of poorly structured outsourcing are often not completely observable at the time activities are completed. We discuss the implications of our findings for capital construction and for outsourcing more generally.
Pooling Data Across Transparently Different Groups of Key Informants: Measurement Equivalence and Survey Research*
Authors: Rungtusanatham M. , Ng C. H. , Zhao X. , Lee T. S. 
Published: March 2008

ABSTRACTSurvey research is often deployed in the study of situational issues facing organizations and functions within organizations. One particular survey research approach can be described as follows: (1) survey questionnaires involving perceptual questions about a situational issue are administered to key informants, one key informant per unit of analysis; (2) key informants vary in a transparent manner across units of analysis such that groups of these key informants are discernible; and (3) perceptual responses, after data collection, are then pooled to create a single larger data set for subsequent statistical manipulations. In this methodological note, we draw attention to this particular survey research approach and ask the question: When is it appropriate to pool data provided by key informants with transparently different demographics across units of analysis so as to create a single larger data set for statistical manipulations? We use a simple example and data from a published study to motivate the relevance and gravity of this methodological question. Offering the concept and empirical assessment of measurement equivalence as the answer to this methodological question of data pooling, we prescribe and demonstrate, with the total quality management→customer satisfaction relationship, the procedural steps for evaluating the seven subdimensions of measurement equivalence. In conclusion, we highlight methods that should be adopted, before data collection, to minimize the risk of violating measurement equivalence. After data collection and for the instances when the empirical assessment for measurement equivalence advises against pooling of such data, we also offer suggestions for analyzing such data and presenting associated statistical results.
Expected Time Value Decay of Options: Implications for Put‐Rolling Strategies
Authors: Tannous George F. , Lee‐Sing Clifton 
Published: March 2008

AbstractAssuming the underlying asset price remains constant, previous studies show that the time value of an option decays gradually at a rate that accelerates over time and peaks at the expiration date. Thus, a significant portion of time value is lost in the four weeks leading up to expiration. This paper shows the time value of currently at‐ or near‐the‐money options should be expected to decay at a rate that decreases over time. The time values of options that are currently deep‐in‐ or deep‐out‐of‐the‐money are expected to initially rise and then resume the normal decay pattern.