bluuebunny/crossref_metadata_2025_split huggingface dataset:
FRACTIONATION OF NUCLEAR, CHLOROPLAST, AND MITOCHONDRIAL DNA FROM POLYSIPHONIA BOLDII (RHODOPHYTA) USING A RAPID AND SIMPLE METHOD FOR THE SIMULTANEOUS ISOLATION OF RNA AND DNA1
Authors: Roell Marina K. , Morse Daniel E. 
Published: October 2004

ABSTRACTExtraction of nucleic acids from red algae is complicated by the presence of phycocolloids. For this reason, methods used for nucleic acid isolation from other organisms are not always amenable to use with red algal preparations; modifications in some cases lead to protocols that are time consuming and complicated, often requiring large amounts of algal tissue for starting material. Here we describe the isolation of both RNA and DNA followed by fractionation and identification of nuclear, chloroplast, and mitochondrial DNAs from a single preparation of Polysiphonia boldii Wynne and Edwards using a simple method that yielded approximately 100 μg of total RNA and 20 μg of total DNA from 1 g of frozen powdered algae. The potent protein denaturant guanidinium thiocyanate and the detergent sarkosyl were used to gently lyse the cells and organelles and immediately inhibit nuclease activity in the extract. The nucleic acids were isolated by ultracentrifugation into a dense solution of CsCl; the RNA was recovered as a pellet and the DNA as a band within the CsCl solution. Agarose gel electrophoresis of the total RNA showed discrete ribosomal RNA bands, indicating little nonspecific degradation. The nuclear, chloroplast, and mitochondrial DNAs were fractionated by density gradient ultracentrifugation in the presence of the DNA binding dye, bisbenzimide H (Hoechst 33258), which binds preferentially to DNA with a high A + T:G + C ratio, thus altering its density to a greater degree than it does that of DNA with a lower nucleotide ratio. The three fractions were identified by Southern blot analysis using heterologous gene probes specific for the different genomes. The protocol should be applicable to different types of algae. The simple nucleic acid isolation step can be performed on multiple samples simultaneously without subsequent fractionation of DNA, allowing comparison of DNA from different individuals, populations, or species.
INFLUENCE OF IRRADIANCE ON CELL VOLUME AND CARBON QUOTA FOR TEN SPECIES OF MARINE PHYTOPLANKTON1
Authors: Thompson Peter A. , Harrison Paul J. , Parslow John S. 
Published: October 2004

ABSTRACTTen species of marine phytoplankton were grown under a range of photosynthetic photon flux densities (PFDs) and examined for variation in cell volume and carbon quota. Results suggest that in response to low PFDs phytoplankton generally reduce their cell volume and frequently reduce their carbon quota. A significant linear relationship between the log of PFD (I) and cell volume (in nine of ten species) and log I and carbon quota (four of ten species) was demonstrated.When exposed, to a transient in light intensity, Thalassiosira pseudonana (Hustedt, clone 3H) Hasle and Heimdal underwent a rapid adaptation in cell volume and carbon quota. Cells going from low light to high light reached maximum mean cell volume within 5 h, and cells going from high light to low light reached a minimum mean cell volume within 12 h. The resulting kinetic constant (k; a measure of the rate of adaptation) was considerably larger than previously reported k values. Ditylum brightwellii (West) Grunow increased in length but did not increase in width during a transient to increased irradiance.Nutrient limitation was shown to override PFD in determining cell volume and carbon quota for Heterosigma akashiwo Hada. Cells grown at equivalent irradiances but N‐limited, were smaller than light‐limited and nutrient‐saturated cells. Therefore, cell volume and carbon quota do not have the same relationship with PFD when factors other than PFD control growth rate.The ecological implications of reduced cell volumes and carbon quotas with decreasing PFD include possible impacts on CO2 budgets, an influence on sinking rates, potential changes in predation rates, and surface area/cell volume benefits.
CHANGE OF UBIQUITINATED PROTEINS DURING THE CELL CYCLE IN CHLAMYDOMONAS (CHLOROPHYTA)1
Authors: Shimogawara Kousuke , Muto Shoshi 
Published: October 2004

ABSTRACTChanges in the amount of heat shock‐related ubiquitinated proteins in Chlamydomonas were investigated during the cell cycle and gamete induction. In a division‐synchronized culture induced by periodic illumination, the amount of the 28‐kDa ubiquitinated protein increased during the dark phase. This increase correlated with the increase of total DNA. Such an increase was repressed when nuclear DNA replication was inhibited with aphidicolin. These results suggest that ubiquitination to form the 28‐kDa protein is involved in nuclear DNA replication or during the cell cycle. The amount of 31‐kDa ubiquitinated protein gradually increased throughout the light phase and decreased in the dark phase. The amount of 28‐kDa ubiquitinated protein also increased during gamete induction caused by nitrogen starvation, while that of the 31‐kDa did not. These results suggest that the change of ubiquitination of 28‐kDa protein mat play a fundamental role in the cell cycle and gamete induction in Chlamydomonas.
FLAGELLAR APPARATUS OF THE BIFLAGELLATE ZOOSPORES OF THE ENIGMATIC MARINE GREEN ALGA BLASTOPHYSA RHIZOPUS1
Authors: Chappell Dorothy F. , O'Kelly Charles J. , Floyd Gary L. 
Published: October 2004

ABSTRACTThe flagellar apparatus of the biflagellate zoospores from Blastophysa rhizopus Reinke has 180° rotational symmetry of the major components and counterclockwise absolute orientation. The basal bodies are connected anteriorly by a prominent striated distal fiber and posteriorly by two proximal striated bands. The C microtubules in the basal bodies terminate proximal to the transition region. Terminal caps and well‐defined proximal sheaths are absent. The four microtubular rootlets diverge at a very small angle from the basal bodies. Six to eight (usually seven) microtubules are present in the s rootlets and two microtubules in the d rootlets. Rootlet 1s is associated with the eyespot. Each d rootlet is subtended by a coarsely striated fiber. Rootlet Id also has a finely striated fiber, roughly opposite the coarsely striated fiber, associated with it. Rhizoplasts and mating structures were not observed. Ultrastructural features of B. rhizopus zoospores are essentially identical with those found in examined members of the Siphonocladales sensu lato (= Siphonocladadales/Cladophorales complex) and Dasycladales, and have relatively few features in common with motile cells of caulerpalean algae. Blastophysa rhizopus probably does not represent an intermediate between the Siphonocladadales and the Caulerpales. Its evolutionary history is different from that of other algae placed in the siphonocladalean family Chaetosiphonaceae. Whether or not Blastophysa is representative of the ancestor to the Siphonodadales and Dasycladales is unclear.
DNA ANALYSIS OF EUKARYOTIC ALGAL SPECIES1
Authors: Coleman Annette W. , Goff Lynda J. 
Published: October 2004

ABSTRACTPlastid genomes of algae resemble those of terrestrial plants in form, size, and rate of nucleotide sequence change. They are circular and range in size from 73 kilobases (kb) to over 400 kb. Their many copies per cell can compose >15% of total cell DNA. Mitochondrial genomes, like plastid genomes, are present in high copy number in preparations of total algal cell DNA. Almost all known algal mitochondrial DNA genomes are relatively small, <50 kb; in some species they are linear, whereas in others they are circular.One of the persistent perplexities for phycologists is the question of what relationship two clones or two groups of organisms bear to each other. Several relatively simple techniques can reveal whether or not two organisms belong to the same clone. Total mitochondrial genome size can be compared directly between isolates, although identity in size does not necessarily mean identity in sequence. Restriction endonuclease digestion combined with probing permits comparison of DNA fragment patterns to see if there is identity or near identity between two samples. This methodology can be applied both to organelle genomes and to nuclear genomes.So far, restriction endonucleases cleave plastid and mitochondrial DNA of organisms belonging to the same gene pool into nearly identical fragment patterns, whereas organisms nearly or totally incapable of interbreeding display patterns wherein ≫ 50% of restriction fragments differ in position on an agarose gel after electrophoresis. Thus, organelle genomes may be the first choice for comparing both total size and restriction endonuclease fragment patterns to obtain an indication of whether two organisms are closely related. This methodology can be applied both to organisms in which interbreeding is easy to test and to the many algae in which homothallism or lack of sexual clones has precluded standard breeding analyses. With further data on variability levels within and between fertile populations, it may be possible to state with confidence whether a sample of morphologically similar organisms shares a common gene pool, even if their breeding cannot be manipulated experimentally.
2‐KETO‐SUGAR ACIDS IN GREEN FLAGELLATES: A CHEMICAL MARKER FOR PRASINOPHYCEAN SCALES1,2
Authors: Becker Burkhard , Becker Dieter , Kamerling Johannis P. , Melkonian Michael 
Published: October 2004

ABSTRACTThe chemical composition of cell walls (thecae) of three taxa of scaly green flagellates (Prasinophyceae) was investigated. The theca of Tetraselmis striata, Tetraselmis tetrathele, and Scherffelia dubia consists mainly of carbohydrate (80% of dry weight), with proteins (5%), calcium (4%), and sulfate (6%) as minor components. The principal sugars (60% of dry weight) are the 2‐keto‐sugar acids 3‐deoxy‐manno‐2‐octulosonic acid (KDO), 3‐deoxy‐manno‐5‐O‐methyl‐2‐octulosonic acid (5OMeKDO), and 3‐deoxy‐lyxo‐2‐heptulosaric acid (DHA). Arabinose, gulose, galactose, galacturonic acid, and in S. dubia, xylose and rhamnose were also found. Examination of scale preparations from Mantoniella squamata, Mesostigma viride, Pyramimonas amylifera, and Nephroselmis olivacea revealed that the 2‐keto‐sugar acids were always associated with the presence of typical prasinophycean scales on the cell surface. In contrast, 2‐keto‐sugar acids were not detected in the cell wall of Chlamydomonas reinhardtii nor in polymer preparations from the culture medium of Chlamydomonas reinhardtii, Dunaliella bioculata, Dunaliella primolecta, Asteromonas gracilis, Hafniomonas reticulate, Pedinomonas tuberculata, Monomastix sp., and Micromonas pusilla. We conclude that 2‐keto‐sugar acids are chemical markers for prasinophycean scales.
KATABLEPHARIS OVALIS, A COLORLESS FLAGELLATE WITH INTERESTING CYTOLOGICAL CHARACTERISTICS1
Authors: Lee Robert Edward , Kugrens Paul 
Published: October 2004

ABSTRACT Katablepharis ovalis Skuja, isolated from an impoundment in Colorado, has a cell covering composed of two layers over the cell body and flagella. The outer component of the cell covering contains 25‐nm‐diameter hexagonal scales arranged in rows. The inner component of the cell covering is composed of a layer of interwoven microfibrils. The inner component of the cell covering is joined to the plasma membrane by one or more attachment strips that always occur outside, and along, one of the microtubular groups of the outer array. The attachment strips resemble hemidesmosomes and are composed of rows of electron‐dense material, 12 nm apart, that protrude through the plasma membrane into the extracellular space, to attach to the inner wall. The two flagella are inserted subapically into a raised area of the cell. The flagella do not have any fibrillar or tubular hairs and are covered only by the two‐layered cell covering. The cell has an inner and outer array of microtubules, both of which are spindle‐shaped, arising at the anterior end of the cell and continuing into the posterior end of the cell. A single large Golgi apparatus occurs in the anterior cytoplasm. The nucleus is in the center of the cell. Two rows of large ejectisomes occur posterior to the area of flagellar attachment. Smaller ejectisomes occur under the plasma membrane in the posterior and medial areas of the cell. Each ejectisome is composed of a single body containing a spirally wound, tapered ribbon. On discharge, the ejectisome ribbon rolls inward, creating a tubular structure. The possible relationship between Katablepharis, the green algae, and the cryptophytes is discussed.
EFFECT OF TEMPERATURE ON GERMINATION OF RHIZOCLONIUM RIPARIUM (SIPHONOCLADALES, CHLOROPHYTA) AKINETES AND ZOOSPORES1
Authors: Hall Deborah J. , Walmsley Richard D. 
Published: October 2004

ABSTRACTThe temperature requirements for germination by reproductive initials of Rhizoclonium riparium (Roth) Harv., a filamentous green alga, were investigated in laboratory culture. Akinetes and zoospores were produced by exposing aging cultures to high temperatures (40°C). Germination proceeded rapidly and followed a typical bell‐shaped response curve, with germination optima between 15 and 20°C. These findings follow the trend found in related algae, i.e. reproductive initials are produced under stressful conditions.
DISTRIBUTION OF TWO TYPES OF EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) IN THE NORTHEAST ATLANTIC REGION AS DETERMINED BY IMMUNOFLUORESCENCE AND COCCOLITH MORPHOLOGY1
Authors: van Bleijswijk Judith , van der Wal Paul , Kempers Rob , Veldhuis Marcel , Young Jeremy R. , Muyzer Gerard , de Vrind‐de Jong Elisabeth , Westbroek Peter 
Published: October 2004

ABSTRACTCulture strains of Emiliania huxleyi (Lohmann 1902) Hay et al. 1967 were placed into two groups designated E. huxleyi type A and type B on the basis of coccolith morphology and immunological properties of the coccolith polysaccharide. We studied the distribution of these types in the North Atlantic region using an indirect immunofluorescence assay with antisera directed against the coccolith polysaccharide of E. huxleyi type A and type B and epifluorescence microscopy. In field samples taken in the Northeast Atlantic Ocean, E. huxleyi type A was found exclusively. In contrast, type B was dominant in the North Sea. Scanning electron microscopy of the samples revealed the same unequal distribution of the two types as found with the immunofluorescent‐labelling assay.
A STATISTICAL CHARACTERIZATION OF GROWTH AMONG CLONES OF SYNURA PETERSENII (SYNUROPHYCEAE)1
Authors: Wee James L. , Millie David F. , Walton Sharon P. 
Published: October 2004

ABSTRACTEach of four clones from the Synura petersenii complex was grown at different pHs (5.5, 6.5, 7.5, 8.5) in batch culture experiments. Growth response curves and exponential growth rates were compared among clones and pH treatments in order to examine growth trend variation among the clonal groups. The clones were isolated from geographically distant North American localities. The clonal groups represented distinct mating types, an isolate and its subisolate, and S. petersenii‐ and S. glabra‐like scale morphologies. No consistent relationship existed between growth response curve, and culture medium pH. Additionally, the trends across time differed according to clone and pH combination. Pairwise comparisons of linear trends from transformed growth response curves indicated two distinct clonal associations. Although the clonal associations corresponded with the final cell density of the cultures, growth response curves did not correspond with mating type, the parent‐isolate and subisolate, or scale morphology. Clones with glabra‐like scales had greater growth rates than the clone with petersenii‐like scales. The conflicting results generated from growth response curve and growth rate analyses support the concept that S. petersenii and S. glabra form a highly variable, homogeneous grouping.
ACCUMULATION OF ASTAXANTHIN IN HAEMATOCOCCUS LACUSTRIS (CHLOROPHYTA)1
Authors: Lee Yuan‐Kun , Soh Chee‐Weng 
Published: October 2004

ABSTRACTIn N‐limited continuous chemostat cultures of the green alga Haematococcus lacustris (Gir.) Rostaf. (UTEX 16), the steady‐state astaxanthin content of the cells was determined by the specific growth rate of the cultures. The highest, pigment content was obtained at the lowest dilution rate. The specific rate of astaxanthin accumulation was, however, a function of the photon flux density measured at the illuminated culture surface. In nongrowing Haematococcus cultures, the specific rate of astaxanthin accumulation was determined by the growth rate of the culture during growth phase. The highest possible cellular astaxanthin content of all cultures was comparable and independent of the culture parameters.
EFFECTS OF LIGHT AND GLYCEROL ON THE ORGANIZATION OF THE PHOTOSYNTHETIC APPARATUS IN THE FACULTATIVE HETEROTROPHPYRENOMONAS SALINA(CRYPTOPHYCEAE)1
Authors: Lewitus Alan J. , Caron David A. , Miller Kenneth R. 
Published: October 2004

ABSTRACTThe marine cryptophytePyrenomonas salinaSantore is capable of autotrophic and heterotrophic nutrition. We studied the physiological and ultrastructural changes that accompany the shift between these nutritional modes. The addition of glycerol to batch cultures ofP. salina,grown at an irradiance limiting for photoautotrophic growth, increased its growth rate and induced specific biochemical and structural changes in its photosynthetic system. Results from extracted pigment analyses, thin‐section electron microscopy, and freeze‐fracture electron microscopy indicated that glycerol addition reduced the cell phycoerythrin content, phycoerythrin to chlorophyll a ratio, degree of thylakoid packing, number of thylakoids · cell−1, and PSII particle size. These properties were reduced to a similar extent in cells grown photoautotrophically under an irradiance saturating for growth. These results are consistent with the hypothesis that enhancement of heterotrophic potential occurs at the expense of light‐harvesting ability in glycerol‐grownP. salina.
PRODUCTION AND SELECTION OF HIGH β‐CAROTENE MUTANTS OF DUNALIELLA BARDAWIL (CHLOROPHYTA)1
Authors: Shaish Aviv , Ben‐Amotz Ami , Avron Mordhay 
Published: October 2004

ABSTRACTWe describe a procedure for the selection of β‐carotenerich mutants of the halotolerant alga Dunaliella bardawil Ben‐Amotz & Avron. Under normal growth conditions the isolated mutants had a several‐fold higher content of β‐carotene than the wild type. Under carotene‐induction conditions, the mutants also possessed a higher β‐carotene content than the wild type. Both the production rate of phytoene and the conversion rate of phytoene to lycopene and β‐carotene were accelerated in the mutants. Cycloheximide, which (in the wild type) inhibits the inductive synthesis of the proteins required for β‐carotene production, had a much smaller effect on β‐carotene biosynthesis in the mutants. We suggest that the mutants are affected in the regulatory path, which controls the induction of high β‐carotene production in Dunaliella.
EFFECT OF GROWTH AND LIGHT/DARK CYCLES ON DIATOM LIPID CONTENT AND COMPOSITION1
Authors: Sicko‐Goad Linda , Andresen Norman A. 
Published: October 2004

ABSTRACTTotal extractable lipid (TEL) and lipid composition were studied throughout the growth cycle in three freshwater diatoms‐Cyclotella meneghiniana Kütz., Melosira varians C. A. Ag., and Stephanodiscus binderanus (Kütz.) Krieg under three light regimes (16:8 h LD, 20:4 h LD, and 12:12 h LD) at 20°C. Two of the diatoms demonstrated strong daylength preferences for growth; C. meneghiniana grew best under long‐day (20: 4‐h LD) conditions, whereas S. binderanus grew best under short‐day (12:12‐h LD) conditions. The lipid composition of the diatoms was similar throughout the growth cycle. Aged (2‐month‐old) cells were high in total lipid and triacylglycerols. Before the onset of active growth and during the early part of active growth, there was a reduction in total neutral lipids, primarily triacylglycerols, and an increase in all polar lipids, including chlorophyll a, acetone‐mobile polar lipids, and phospholipids. While cell numbers were still increasing, triacylglycerols increased and polar lipids decreased to levels near those found in aged cultures, Results suggest that increased triacylglycerol content of freshwater diatoms is not necessarily indicative of senescent populations.
Locus control region elements HS2 and HS3 in combination with chromatin boundaries confer high‐level expression of a human β‐globin transgene in a centromeric region
Authors: Kang Sung‐Hae Lee , Levings Padraic P. , Andersen Felicie , Laipis Philip J. , Berns Kenneth I. , Zori Robert T. , Bungert Jörg 
Published: October 2004

Expression constructs are subject to position‐effects in transgenic assays unless they harbour elements that protect them from negative or positive influences exerted by chromatin at the site of integration. Locus control regions (LCRs) and boundary elements are able to protect from position effects by preventing heterochromatization of linked genes. The LCR in the human β‐globin gene locus is located far upstream of the genes and composed of several erythroid specific DNase I hypersensitive (HS) sites. Previous studies demonstrated that the LCR HS sites act synergistically to confer position‐independent and high‐level globin gene expression at different integration sites in transgenic mice. Here we show that LCR HS sites 2 and 3, in combination with boundary elements derived from the chicken β‐globin gene locus, confer high‐level human β‐globin gene expression in different chromosomal integration sites in transgenic mice. Moreover, we found that the construct is accessible to nucleases and highly expressed when integrated in a centromeric region. These results demonstrate that the combination of enhancer, chromatin opening and boundary activities can establish independent expression units when integrated into chromatin.
The relationships between fish health, metabolic rate, swimming performance and recovery in return‐run sockeye salmon, Oncorhynchus nerka (Walbaum)
Authors: Tierney K B , Farrell A P 
Published: October 2004

AbstractThe repeat swimming ability and oxygen uptake (Mo2) of adult sockeye salmon, Oncorhynchus nerka (Walbaum), were assessed at ambient water temperatures at three field locations along their migration route. Following these measurements, internal and external fish condition was evaluated according to United States Environmental Protection Agency guidelines. Here we report on the physiological characteristics of fish having either moderate or severe levels of disease and injury. Routine oxygen uptake (Mo2) did not differ between healthy fish and those with indices of ill health. In contrast, fish classified as sick, which included conditions of damaged internal organs, an Ichthyophonus spp. heart infection, a Saprolegnia spp. gill infection, and skin wounds, had a lower post‐exercise Mo2 and were unable to repeat their critical swim speed (Ucrit) on the second swim test. Moderate levels of disease or injury did not significantly affect either Ucrit or post‐exercise Mo2. We conclude that the ability of adult salmon to recover quickly from exercise may be a useful indicator of sublethal pathologies.