bluuebunny/crossref_metadata_2025_split huggingface dataset:
SODIUM: SOME EFFECTS ON BLUEGREEN ALGAL GROWTH1
Authors: Ward Amelia K. , Wetzel Robert G. 
Published: August 2007

SUMMARYThe growth of heterocystous bluegreen algae in various concentrations of sodium, was examined in axenic culture as well as in situ studies. Anabaena cylindrica Lemm. with no Na+ added, suffered from decreased rates of acetylene reduction, 14C, assimilation, excretion of organic C as well as lower concentrations of chlorophyll a and particulate organic C compared to cultures supplied with 5, 10, and 50 mg Na+·l−1 Sodium deficient algae released, extracellularly a higher percentage of previously fixed C as organic C. No differences in any parameter measured were demonstrable among cultures grown with 5, 10, and 50 mg Na+·l−1 High nitrate concentrations (20 mg NO3−·l−1) resulted in decreased rates of acetylene reduction and heterocyst numbers in. Na sufficient, and Na deficient cultures: however, decreased, cellular Na content at high NO3− levels occurred only in N deficient, cultures. Higher percentages of excreted organic C occurred with increasing NO3− concentrations in Na deficient cultures. Sodium enrichment of natural bluegreen populations with the addition of 50, 100, and 200 mg Na+·l−1 elicited neither a stimulatory nor an inhibitory response in photosynthetic C fixation. In contrast, the addition of small amounts of Na+ (5 mg·l−) resulted in increased C fixation. However, since the Na. concentration of the lake water, at ca. 5 mg Na+·l−1, was sufficient for growth of the bluegreens present, sodium, is not assumed to be limiting under most natural conditions. No increase in in situ acetylene reduction rates occurred with additions of sodium.
EFFECTS OF LOW NITROGEN LEVELS AND VARIOUS NITROGEN SOURCES ON GROWTH AND WHORL DEVELOPMENT IN ACETABULARIA (CHLOROPHYTA)1
Authors: Adamich Marina , Gibor Aharon , Sweeney Beatrice M. 
Published: August 2007

SUMMARYNitrate, ammonia, urea, and glycine were compared as nitrogen sources for Acetabularia mediterranea. Cells grew normally in media containing nitrate or urea, while cells did not grow at all when the same amount of N was supplied as ammonium ion. The utilization of glycine remains questionable. Cells in medium without added N (NDM) increased in length and some formed reproductive caps.The whorls of vegetative cells showed considerable hypertrophy in NDM and in glycine. This hypertrophy was due to the elongation of only the first‐(a1) and second‐ (a2) order articles. When cut, the basal portion of cells without added N regenerated new apices with whorls. The development of these whorls was inversely proportional to the NO2 concentration.Analyses showed that the intracellular nitrogen pool in young cells and regenerating bases was very small, about 1/10 of that of fully grown cells. Therefore we suggest that trace amounts of N contaminants in the medium supported growth and development, the uptake of which was facilitated by the hypertrophied whorls, under N‐limited conditions.
CHLOROPLAST PIGMENT PATTERNS IN DINOFLAGELLATES1
Authors: Jeffrey S. W. , Sielicki Margarete , Haxo F. T. 
Published: August 2007

SUMMARYThe chlorophylls and carotenoids of 22 species of dinoflagellates were analysed by thin layer chromatography, using 2‐dimensional sucrose plates, and 1‐dimensional polyethylene plates for chlorophylls c1and c2. Peridinin was the major carotenoid in 19 of the species, while fucoxanthin was the major carotenoid in 3. In the peridinin‐containing species, 5 carotenoid fractions, constituting more than 95% of the total carotenoids, were always present. These were peridinin (± neo‐peridinin), averaging 64% of the total carotenoid, diadinoxanthin, dinoxanthin, β‐carotene and a polar, unidentified pink xanthophyll. Six other carotenoid fractions occurred in minor or trace quantities among the species, but were not identified. Two of these had, a wide distribution; the other 4 were restricted to one or 2 species. The chlorophyll content of the dinoflagellate cultures ranged from 1–141 μg chlorophyll a + c/106cells, a pattern which was broadly correlated with cell size. In the peridinin‐containing species the ratio of chlorophyll a to c on a molar basis was approximately 2 (range 1.60–4.39); in the fucoxanthin‐containing species this ratio was approximately 4 (range 2.65–5.73). Both chlorophylls c1and c2occurred in the fucoxanthin‐containing dinoflagellates, and only chlorophyll c2(one exception) occurred in the peridinin‐containing dinoflagellates. These patterns of chlorophyll c and major carotenoid correspond to patterns previously observed in the Pyrrhophyta and the Chrysophyta, suggesting different phylogenetic origins for the “dinoflagellate” chloroplasts.
NORTH CAROLINA MARINE ALGAE. VI. SOME CERAMIALES (RHODOPHYTA), INCLUDING A NEW SPECIES OF DIPTEROSIPHONIA1
Authors: Schneider Craig W. 
Published: August 2007

SUMMARYSix members of the Ceramiales are added to the flora of North Carolina. Two of these, Acrosorium uncinatum (Turner) Kylin and, Rhododictyon bermudensis Taylor, are also reported from South Carolina for the first time. One species, Mesothamnion boergeseni Joly, was previously known only from Brazil and another, Dipterosiphonia reversa sp. nov., is added to the algal literature for the first time. Evidence is presented for the reassignment of R. bermudensis from the Dasyaceae to the Ceramiaceae.
KINETICS OF SILICON‐LIMITED GROWTH IN THE FRESHWATER DIATOM ASTERIONELLA FORMOSA1,2
Authors: Kilham Susan Soltan 
Published: August 2007

SUMMARYGrowth rates of two clones of the freshwater planktonic diatom Asterionella formosa Hass. were measured under conditions in which external silicon concentrations controlled growth. Clone AfOH2 from Lake Ohrid, Yugoslavia, had a higher maximum growth rate (μmax= 1.11 doublings/day) and apparent half‐saturation constant (Ksi] + Sio= 1.93 μM Si) than clone L262 from Lake Windermere, England. (μmax= 0.61 doublings/day; Ksi+ Sio= 1.09 μM Si). Klim, the silicon concentration at μ= 0.9 μmax, is 13.8 μM Si for clone AfOH2 and 6.5 μM Si for clone L262. These values agree well with published field observations showing A. formosa populations decreasing below 0.5 mg/l SiO2 (= 8.4 μM Si). Calculations of yield gave a range of 0.5–1.5 μM Si/106 cells for clone AfOH2 and 0.6–1.9 μM Si/106 cells for clone L262.
A SENSITIVE ALGAL ASSAY: AN IMPROVED METHOD FOR ANALYSIS OF FRESHWATERS1
Authors: Klotz R. L. , Cain J. R. , Trainor F. R. 
Published: August 2007

SUMMARYAn algal assay capable of detecting the carrying capacity of nutrient‐poor rivers was developed. In order to eliminate carry‐over of nutrients, thus masking the true nutrient condition of the water tested, a new growth medium was developed. This maintenance medium contained less than 4 mg · 1−1 total inorganic salts. With an inoculum of 104 cells‐ml−1 the test organism Selenastrum capricornutum Printz was grown in sterile‐filtered, river water and transferred daily with a 1:1 dilution. The assay was carried out for 4 or 5 days, at which time cell number was calculated, and the doublings per day were determined. Comparisons are made with similar but less sensitive assays, on the basis of both daily and 5‐day readings.
EFFECTS OF ENVIRONMENTAL FACTORS ON PHOTOSYNTHESIS PATTERNS INPHAEODACTYLUM TRICORNUTUM(BACILLARIOPHYCEAE). I. EFFECT OF NITROGEN DEFICIENCY AND LIGHT INTENSITY1
Authors: Glover Hilary , Beardall John , Morris Ian 
Published: August 2007

SUMMARYCultures of the marine diatomPhaeodactylum tricornutumBohlin incorporated, a large proportion of the total fixed carbon (50% or more) into amino acids and amides during short periods of photo‐assimilation of14C‐labelled carbon dioxide. Although increasing nitrogen limitation in a nitrate‐limited chemostat had little significant effect on the proportion of C incorporated into amino acids and amides combined, it did affect the distribution of radioactivity within individual compounds of this group. In particular, increasing degrees of N deficiency reduced the proportion incorporated into amides to almost undetectable levels, reduced the proportion in alanine and increased the proportion in glutamic acid. Also, increasing N limitation decreased the relative synthesis of sugar phosphates and increased the proportion of C assimilated into intermediates of the tricarboxylic acid cycle. Reduced light intensity did not have any significant effect on the proportion of C incorporated into the total amino acids and amides, but did cause a decrease in the radioactivity
EFFECTS OF ENVIRONMENTAL FACTORS ON PHOTOSYNTHESIS PATTERNS IN PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE). II. EFFECT OF OXYGEN1
Authors: Beardall John , Morris Ian 
Published: August 2007

SUMMARYOxygen inhibited the rate of light‐saturated photosynthesis of the marine diatom Phaeodactylum tricornutum Bohlin. However, inhibition could only be detected with O2 concentrations approaching 100%. Atmospheric concentrations of O2 (21%) had little effect on photosynthesis. In this, Phaeodactylum more closely resembles the so‐called C‐4 plants which show low rates of photorespiration. The results presented here agree with others in showing increased O2 inhibition at reduced bicarbonate concentrations. The biochemical mechanism of photorespiration in Phaeodactylum appears to be similar to that reported for other photosynthetic systems.The activity of ribulose‐1,5 diphosphate (RuDP) carboxylase in cell‐free extracts was also inhibited, by oxygen. Inhibition by O2 was optimal at pH 9.2 as was the RuDP‐dependent O2 uptake. RuDP carboxylase/oxygenase ratios decreased with increasing pH and were greater in cells grown at lower light intensities. Carboxylase levels were less affected by the light intensity for growth than were the levels of the oxygenase.Short‐term incorporation of NaHCO3‐14C by cells grown at high light intensities showed increased labelling of glycolate and glycine plus serine under O2 compared with nitrogen. There was a concomitant decrease in the radioactivity found in phosphoglyeric acid (PGA) and sugar phosphates in the presence of O2. The effects of O2 on the short‐term pattern of photosynthesis were less marked when the alga was previously grown at low light intensities.
EFFECT OF AMMONIA ON PHOTOSYNTHETIC RATE AND PHOTOSYNTHATE RELEASE BY AMPHIDINIUM CARTERAE (DINOPHYCEAE)1
Authors: Byerrum R. U. , Benson A. A. 
Published: August 2007

SUMMARYAmmonia concentration between 10–300 μM in 75% seawater in which Amphidinium carterae Hulb, was allowed to photosynthesize caused an increased rate of photosynthesis. In addition, these same concentrations caused the dinoflagellate to release to the medium up to 50% of the carbon fixed during the 30 min period of photosynthesis used in the experiments.
LIGHT AND ELECTRON MICROSCOPE OBSERVATIONS ON MOTILE CELLS OFPORPHYRIDIUM PURPUREUM(RHODOPHYTA)1,2
Authors: Lin Hsiu‐ping , Sommerfeld Milton R. , Swafford James R. 
Published: August 2007

SUMMARYMotile cells of the unicellular red alga,Porphyridium purpureum(Bory) Drew & Ross were studied using light, interference, and electron microscopy. In liquid culture, moving cells possessed a mucilaginous stalk which extended from one end of the cell and tapered to a point. On tin agar surface, distinct trails were left by moving cells. With interference microscopy, the trails appeared to be shallow grooves. Microscopy of shadowed replicas confirmed that moving cells produced a shallow groove as they moved across agar. Ultrastructure observations revealed that cells moving on agar exhibited morphological polarity. Large vesicular elements containing fibrillar material similar to that in the cellular sheath was associated with the posterior area of the motile cells.
PRODUCTS OF PHOTOSYNTHESIS IN CAULERPA SIMPLICIUSCULA (CHLOROPHYCEAE)1
Authors: Howard Russell J. , Gayler Ken R. , Grant Bruce R. 
Published: August 2007

SUMMARYThe kinetics of carbon flow through various metabolites of Caulerpa simpliciuscula C. Ag., a siphonaceous green alga, are described. The pattern of C fixation in this alga differs from those observed in higher plants and other green algae in a number of respects. After 40 min incubation, soluble β‐linked polyglucans are the most important labelled carbohydrates. Sucrose, although delectable, is never a major recipient of label and does not label until after other oligosaccharide fractions. The sugar monophosphates contain a large proportion of the 14C assimilated even after 40 min and behave not only as metabolic intermediates, but also as storage pools. The pattern of ammo acid labelling resembles that reported for other species of green algae in that alanine becomes labelled most rapidly, followed by glycine, and much later by glutamate, glutamine and asparagine. These labelling patterns are discussed in the light, of what is known of patterns of C flow in other algae.
Measurement of Interface Fracture Toughness of Sandwich Structures under Mixed Mode Loadings
Authors: Østergaard Rasmus C. , Sørensen Bent F. , Brøndsted Povl 
Published: August 2007

Fracture of sandwich structures loaded with axial forces and bending moments is analyzed in the context of linear elastic fracture mechanics. A closed form expression for the energy release rate of interface cracking of a sandwich specimen is found by analytical evaluation of the J-integral. A method for determining the mode mixity is described and applied. Expressions are presented whereby the mode mixity can be calculated analytically for any load combination when the mode mixity is known for just one load case. The theory presented is applied to a new test method based on double cantilever beam sandwich specimens loaded with uneven bending moments. The interface fracture toughness of two sandwich types are measured as function of the mode mixity. The sandwich structures that are tested consist of glass fiber reinforced polyester skins and PCV core. The tests show that the interface fracture toughness depends strongly on the mode mixity. Under dominated normal crack opening, the crack grows just below the interface in the core at a constant fracture toughness. Under dominated tangential crack deformation, the crack grows into the laminate resulting in extensive fiber bridging and an increase in fracture toughness. As a result of the development of a large process zone due to fiber bridging, the analysis by linear elastic fracture mechanics becomes invalid and modeling with cohesive zones is proposed.
The topology of metabolic isotope labeling networks
Authors: Weitzel Michael , Wiechert Wolfgang , Nöh Katharina 
Published: August 2007

Abstract

Background
Metabolic Flux Analysis (MFA) based on isotope labeling experiments (ILEs) is a widely established tool for determining fluxes in metabolic pathways. Isotope labeling networks (ILNs) contain all essential information required to describe the flow of labeled material in an ILE. Whereas recent experimental progress paves the way for high-throughput MFA, large network investigations and exact statistical methods, these developments are still limited by the poor performance of computational routines used for the evaluation and design of ILEs. In this context, the global analysis of ILN topology turns out to be a clue for realizing large speedup factors in all required computational procedures.

Results
With a strong focus on the speedup of algorithms the topology of ILNs is investigated using graph theoretic concepts and algorithms. A rigorous determination of all cyclic and isomorphic subnetworks, accompanied by the global analysis of ILN connectivity is performed. Particularly, it is proven that ILNs always brake up into a large number of small strongly connected components (SCCs) and, moreover, there are natural isomorphisms between many of these SCCs. All presented techniques are universal, i.e. they do not require special assumptions on the network structure, bidirectionality of fluxes, measurement configuration, or label input. The general results are exemplified with a practically relevant metabolic network which describes the central metabolism of E. coli comprising 10390 isotopomer pools.

Conclusion
Exploiting the topological features of ILNs leads to a significant speedup of all universal algorithms for ILE evaluation. It is proven in theory and exemplified with the E. coli example that a speedup factor of about 1000 compared to standard algorithms is achieved. This widely opens the door for new high performance algorithms suitable for high throughput applications and large ILNs. Moreover, for the first time the global topological analysis of ILNs allows to comprehensively describe and understand the general patterns of label flow in complex networks. This is an invaluable tool for the structural design of new experiments and the interpretation of measured data.
A statistical method to incorporate biological knowledge for generating testable novel gene regulatory interactions from microarray experiments
Authors: Larsen Peter , Almasri Eyad , Chen Guanrao , Dai Yang 
Published: August 2007

Abstract

Background
The incorporation of prior biological knowledge in the analysis of microarray data has become important in the reconstruction of transcription regulatory networks in a cell. Most of the current research has been focused on the integration of multiple sets of microarray data as well as curated databases for a genome scale reconstruction. However, individual researchers are more interested in the extraction of most useful information from the data of their hypothesis-driven microarray experiments. How to compile the prior biological knowledge from literature to facilitate new hypothesis generation from a microarray experiment is the focus of this work. We propose a novel method based on the statistical analysis of reported gene interactions in PubMed literature.

Results
Using Gene Ontology (GO) Molecular Function annotation for reported gene regulatory interactions in PubMed literature, a statistical analysis method was proposed for the derivation of a likelihood of interaction (LOI) score for a pair of genes. The LOI-score and the Pearson correlation coefficient of gene profiles were utilized to check if a pair of query genes would be in the above specified interaction. The method was validated in the analysis of two gene sets formed from the yeast Saccharomyces cerevisiae cell cycle microarray data. It was found that high percentage of identified interactions shares GO Biological Process annotations (39.5% for a 102 interaction enriched gene set and 23.0% for a larger 999 cyclically expressed gene set).

Conclusion
This method can uncover novel biologically relevant gene interactions. With stringent confidence levels, small interaction networks can be identified for further establishment of a hypothesis testable by biological experiment. This procedure is computationally inexpensive and can be used as a preprocessing procedure for screening potential biologically relevant gene pairs subject to the analysis with sophisticated statistical methods.
The mitochondrial DNA control region shows genetically correlated levels of heteroplasmy in leukocytes of centenarians and their offspring
Authors: Rose Giuseppina , Passarino Giuseppe , Scornaienchi Vittorio , Romeo Giuseppe , Dato Serena , Bellizzi Dina , Mari Vincenzo , Feraco Emidio , Maletta Raffaele , Bruni Amalia , Franceschi Claudio , De Benedictis Giovanna 
Published: August 2007

Abstract

Background
Studies on heteroplasmy occurring in the mitochondrial DNA (mtDNA) control region (CR) in leukocytes of centenarians and younger subjects have shown that the C150T somatic transition is over-represented in centenarians. However, whether the occurrence/accumulation of heteroplasmy is a phenotypic consequence of extreme ageing or a genetically controlled event that may favor longevity is a question that deserves further attention. To clarify this point, we set up a Denaturing High Performance Liquid Chromatography (DHPLC) protocol to quantify mtDNA CR heteroplasmy. We then analyzed heteroplasmy in leukocytes of centenarians (100 subjects), their offspring and nieces/nephews (200 subjects, age-range 65–80 years, median age 70 years), and in leukocytes of 114 control subjects sex- and age-matched with the relatives of centenarians.

Results
The centenarians and their descendants, despite the different ages, showed similar levels of heteroplasmy which were significantly higher than levels in controls. In addition we found that heteroplasmy levels were significantly correlated in parent-offspring pairs (r = 0.263; p = 0.009), but were independent of mtDNA inherited variability (haplogroup and sequence analyses).

Conclusion
Our findings suggest that the high degree of heteroplasmy observed in centenarians is genetically controlled, and that such genetic control is independent of mtDNA variability and likely due to the nuclear genome.
Design and evaluation of Actichip, a thematic microarray for the study of the actin cytoskeleton
Authors: Muller Jean , Mehlen André , Vetter Guillaume , Yatskou Mikalai , Muller Arnaud , Chalmel Frédéric , Poch Olivier , Friederich Evelyne , Vallar Laurent 
Published: August 2007

Abstract

Background
The actin cytoskeleton plays a crucial role in supporting and regulating numerous cellular processes. Mutations or alterations in the expression levels affecting the actin cytoskeleton system or related regulatory mechanisms are often associated with complex diseases such as cancer. Understanding how qualitative or quantitative changes in expression of the set of actin cytoskeleton genes are integrated to control actin dynamics and organisation is currently a challenge and should provide insights in identifying potential targets for drug discovery. Here we report the development of a dedicated microarray, the Actichip, containing 60-mer oligonucleotide probes for 327 genes selected for transcriptome analysis of the human actin cytoskeleton.

Results
Genomic data and sequence analysis features were retrieved from GenBank and stored in an integrative database called Actinome. From these data, probes were designed using a home-made program (CADO4MI) allowing sequence refinement and improved probe specificity by combining the complementary information recovered from the UniGene and RefSeq databases. Actichip performance was analysed by hybridisation with RNAs extracted from epithelial MCF-7 cells and human skeletal muscle. Using thoroughly standardised procedures, we obtained microarray images with excellent quality resulting in high data reproducibility. Actichip displayed a large dynamic range extending over three logs with a limit of sensitivity between one and ten copies of transcript per cell. The array allowed accurate detection of small changes in gene expression and reliable classification of samples based on the expression profiles of tissue-specific genes. When compared to two other oligonucleotide microarray platforms, Actichip showed similar sensitivity and concordant expression ratios. Moreover, Actichip was able to discriminate the highly similar actin isoforms whereas the two other platforms did not.

Conclusion
Our data demonstrate that Actichip is a powerful alternative to commercial high density microarrays for cytoskeleton gene profiling in normal or pathological samples. Actichip is available upon request.