bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROTEIN TURNOVER AND HETEROCYST DIFFERENTIATION IN THE CYANOBACTERIUM ANABAENA VARIABILIS1
Authors: Thiel Teresa 
Published: October 2004

ABSTRACTUnder conditions of starvation for fixed nitrogen, cells of the filamentous cyanobacterium Anabaena variabilis Kütz, degrade much of their protein prior to heterocyst differentiation. Cells starved for a source of fixed nitrogen initially degraded about 2% of their protein per hour; by 24 h after nitrogen stepdown about 40% of the protein was degraded. Most of the acid‐soluble radiolabeled material was excreted into the medium. Proteolysis was completely inhibited by chloramphenicol, by cyanide, or in the dark, hut was only partially inhibited in the presence of dichlorophenyl dimethylurea. Methionine sulfoximine (MSX) (an inhibitor of glutamine synthetase) in the presence of ammonia caused heterocysts to form. MSX treated cells degraded protein; however, the amount of protein degraded was much less than in cells starved for ammonia. Glutamine, which can serve as a nitrogen source for this strain, did not prevent starvation‐induced proteolysis and did not prevent the differentiation of heterocysts.
MONOCLONAL ANTIBODIES SPECIFIC FOR SULFATED POLYSACCHARIDES ON THE SURFACE OF MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1
Authors: Eardley Diane D. , Sutton Celia W. , Hempel William M. , Reed Daniel C. , Ebeling Alfred W. 
Published: October 2004

ABSTRACTOne of the principal polysaccharides in the cell wall of brown algae is fucoidan, a highly branched polymer of 1,2‐fucose with a sulfate group on the fourth carbon. In this report, we describe a set of monoclonal antibodies generated to the cell walls of gametophytes of the kelp, Macrocystis pyrifera (Linnaeus). C. Agardh. Ascites fluids of a set of four antibodies with specificity for the cell wall were purified by filtration chromatography. Each of these antibodies was specifically reactive with fucoidan, and one of the antibodies cross‐reacted with ascophyllan, which is a xyloglycuronan. The antibodies reacted in an immunofluorescence assay with surface determinants on the gametophytes of both Macrocystis pyrifera and Pterygophora californica Ruprecht which belong to different families in the order Laminariales. One of the antibodies (3H8) was further characterized for antigen fine specificity using an enzyme immunoassay. This antibody was specific for sulfate determinants present on fucoidan and related polysaccharides. Orientation of the sulfate was an important element in antibody specificity. Immunofluorescence microscopy carried out during the first four days of development in Pterygophora showed that the antigenic determinant recognized by the 3H8 antibody was present on spore capsules (embryospores) as well as the developing gametophyte. These results show that a sulfated epitope on fucoidan is present on the surface of the gametophyte shortly after germination and that it persists during the early stages of development. Our results indicate that any immunological differences between the morphologically similar gametophytes of the two helps are more likely to be quantitative than qualitative. Such differences may reflect differential mobilization of fucans during the process of germination and early development.
COMPARATIVE ANALYSIS OF THE DINOFLAGELLATE FLAGELLAR APPARATUS IV. GYMNODINIUM ACIDOTUM1
Authors: Farmer Mark A. , Roberts Keith R. 
Published: October 2004

ABSTRACT Gymnodinium acidotum Nygaard is a freshwater dinoflagellate that is known to harbor a cryptomonad endosymbiont whose chloroplasls give the organism an overall blue‐green color. The ultrastructure of G. acidotum was examined with particular attention being given to the three dimensional nature of the flagellar apparatus. The fiagellar apparatus is composed of two functional basal bodies that are slightly offset and lie at an angle of approximately 90° to one another. As in other dinoflagellates the transverse basal body is associated with a striated, fibrous root that extends from the proximal end of the basal body to the transverse flagellar opening. At least one microtubular root extends from the proximal end of the transverse basal body, and a multi‐membered longitudinal microtubular root is associated with the longitudinal basal body. The most striking feature of the flagellar apparatus of G. acidotum is the large fibrous connective that extends from the region of the proximal ends of the basal bodies to the cingulum on the dorsal side of the cell. A similar structure has been reported from only one other dinoflagellate, Amphidinium cryophilum Wedemayer, Wilcox, and Graham. The presence of this structure as well as similarities in external morphology suggest thai these two species may be more closely related to each other than either is to other gymnodinioid taxa. The taxonomic importance of dinoflagellate flagellar apparatus components is discussed.
FINE STRUCTURE OF THE FLAGELLAR APPARATUS OF DINOBRYON CYLINDRICUM (CHRYSOPHYCEAE)1
Authors: Owen Heather A. , Mattox Karl R. , Stewart Kenneth D. 
Published: October 2004

ABSTRACTThe three‐dimensional structure of the flagellar apparatus of Dinobryon cylindrioum Imhof. (UTEX no. LB 2266) was determined using serial section reconstruction. Four microtubular rootlet systems (R1, R2, R3, and R4)and a rhizoplast are present, following the general pattern found in other chrysophytes. The R1 rootlet, containing seven microtubules, originates at the basal body of the long flagellum that bears mastigonemes (F1). The R1 rootlet forms an arc which curves in clockwise direction (when viewed from the anterior end of the cell) approximately halfway around the pit from which the short smooth flagellum (F2) emerges. Numerous microtubules cascade from the exterior‐facing side of this rootlet to the tail of the cell. The R2 rootlet originates between the F1 and F2 basal bodies, is attached to the F1 basal body by a fibrous connection, and forms a clockwise arc above the R1 rootlet. This rootlet extends approximately one quarter of the way around the pit. The R3 rootlet system originates as a trough‐shaped band of six microtubules spanning the distance between the proximal ends of the F1 and F2 basal bodies. The six‐membered rootlet splits into two parts, designated R3 and R3. Both parts circle the pit in counter‐clockwise direction, pass beneath the F2 basal body, and descend into the cell alongside the chloroplast. The R4 rootlet originates in fibrous material, passes diagonally over the top of the F2 basal body, forms a clockwise loop at least three quarters of the way around the pit to the interior of the R3 and R3 rootlets, and ends in the cytoplasm.Similarities of rootlet origins and other details of the flagellar apparatus of D. cylindricum with those of other heterokont organisms reinforce the idea that these organisms are phylogenetically related.
ABSOLUTE CONFIGURATION OF THE FLAGELLAR APPARATUS OF BIFLAGELLATE ZOOSPORES OF ENTEROMORPHA FLEXUOSA SSP. PILIFERA (ULVOPHYCEAE, CHLOROPHYTA)1
Authors: Leonardi Patricia I. , Cáceres Eduardo J. 
Published: October 2004

ABSTRACTThe absolute configuration of the flagellar apparatus of biflagellate zoospores of Enteromorpha flexuosa (Wulfen ex Roth.) J. Agardh ssp. pilifera (Kütz.) Bliding was determined. Viewed from the anterior of the cell, the flagellar apparatus shows 180° rotational symmetry with a counter‐clockwise absolute orientation of its components. In longitudinal sections, the posteriorly directed basal bodies form an angle of about 170°–180° to one another. A reduced striated distal fiber connects the two basal bodies. The cruciate microtubular rootlet system has a 4–2–4–2 alternation pattern. Striated microtubule‐associated components (SMACs or system I‐fibers) and rhizoplasts (or system II fibers) accompany the two‐membered rootlets. Striated bands connect the proximal sheaths with the four‐Membered rootlets. The bilobate terminal caps do not completely cover the proximal ends of the basal bodies. This is the first ultrastructural study of biflagellate zoospores in a member of the Ulvales.
SEA ICE DIATOMS (BACILLARIOPHYCEAE) OF THE CANADIAN ARCTIC. I. THE GENUS STENONEIS1
Authors: Poulin Michel 
Published: October 2004

ABSTRACTIce diatom assemblages in the Canadian Arctic are dominated by the Naviculaceae, a family which includes the genus Stenoneis Cleve. A taxonomic history of S. inconspicua var. baculus (Cleve) Cleve (including type material of Navicula baculus Cleve) is presented with morphological data including the first SEM views of the genus. Stenoneis inconspicua var. baculus was compared with S. obtuserostrata (Hustedt) comb. nov. (basionym: Navicula obtuserostrata Hustedt). In the SEM, external, short, flattened siliceous ridges were revealed beside the proximal parts of the raphe branches and central pores. This may be a significant taxonomic feature of the genus. Valves of S. inconspicua var. baculus ranged from 40–103 μm in length, 7–11 μm in width and had 17–20 striae in 10 μm, whereas valves of S. obtuserostrata were shorter (27–53 μm), narrower (6–7.5 μm) and more finely striated (24–30 in 10 μm). Both taxa have a circumpolar Arctic distribution.
SYSTEMATIC ANALYSIS OFSPHAEROPLEA(CHLOROPHYCEAE)1
Authors: Buchheim Mark A. , Nickrent Daniel L , Hoffman Larry R. 
Published: October 2004

ABSTRACTA systematic investigation of the genusSphaeropleawas conducted using cladistic analyses of both structural and isozyme characters for the same set of taxa. The structural data were not able to fully resolve some of the taxa while the isozyme data did produce a tree in which all nodes were supported by data. The structural characters were relatively consistent with one another, whereas the isozyme characters were much less internally consistent. Results from independent, cladistic analyses of both data sets support the concept that among thoseSphaeropleaspecies investigated,S. fragilisBuchheim et Hoffman had an early divergence. The two data sets differed primarily in that the structural data support monophyly of the genusSphaeropleaand the isozyme data do not. The greater relative consistency of the structural data suggests better support for trees inferred from its analysis. Furthermore, searches for character congruence between the two data sets revealed isozyme data which support monophyly of the genusSphaeroplea, but had been overwhelmed by conflicting isozyme characters.
PHYLOGENY OF GRACILARIA LEMANEIFORMIS (RHODOPHYTA) BASED ON SEQUENCE ANALYSIS OF ITS SMALL SUBUNIT RIBOSOMAL RNA CODING REGION1
Authors: Bhattacharya Debashish , Elwood Hille J. , Goff Lynda J. , Sogin Mitchell L. 
Published: October 2004

ABSTRACTThe small subunit ribosomal RNA (rRNA) sequence of Gracilaria lemaneiformis Bory Weber‐van Bosse was inferred from analysis of rRNA coding regions that were amplified by the polymerase chain reaction method. Comparison of the G. lemaneiformis small subunit rRNA to homologous genes of diverse eukaryotes demonstrated that the red algal divergence was nearly simultaneous with the separation of plants, fungi, animals and many other protist lineages. This result conflicts with those of 5S rRNA sequence and plastid based phytogenies which suggest that red algae represent an early divergence in the eukaryotic line of descent. Further, algae appear to be of polyphyletic origin and red algae are unrelated to higher fungi.
VARIATION IN DCMU‐ENHANCED FLUORESCENCE RELATIVE TO CHLOROPHYLL A: CORRELATION WITH THE BROWN TIDE BLOOM1
Authors: Keller Aimee A. , Rice Robin L. 
Published: October 2004

ABSTRACTDCMU–enhanced fluorescence and extracted chlorophyll a were simultaneously measured in Narragansett Bay, Rhode Island and the MERL (Marine Ecosystems Research Laboratory) mesocosms during the 1985 brown tide bloom. Marked differences in the relationship between these variables were observed as the phytoplankton community shifted from dominance by picoalgae to diatoms. The fluorescence to chlorophyll a ratio was significantly (P< 0.05) higher in the mesocosms and the bay when the brown tide species (Aureococcus anophagefferens Hargraves et Sieburth) dominated the phytoplankton community compared with other taxa. Although several factors could have affected the relationship we believe the high ratios are related to the pigment composition and/or small size of the brown tide organism.
UNCOUPLING OF VARIOUS MEASURES OF GROWTH IN ULVA ROTUXDATA(CHLOROPHYTA) FOLLOWING A LARGE DECREASE IN IRRADIANCE1
Authors: Henley William J. 
Published: October 2004

ABSTRACTA vegetative clone of the chlorophyte macroalga Ulva rotundata Blid. was maintained in an outdoor continuous flow system and subjected to a large decrease in irradiance. Specific growth rates based on changes in fresh (μFW) and dry weight (μDW) and surface area (μSA) were determined using precut disks over the 24 h following a post‐sunset transfer from full sunlight (100% I0) to 9% I0 All three measures of growth rate were approximately equivalent for untransferred control plants at either limiting (9%) or saturating (100%)I0. Transferred disks exhibited μFW and μSA which were slightly lower than 100%I0 controls and much higher than 9% I0 controls; μDW was nearly identical for transferred disks and 9% I0 controls. Cell size was unchanged following transfer, indicating that surface area changes reflected a proportional increase in cell number. Cell division therefore continued at a high rate for one day following transfer of U. rotundata to irradiances which are subsaturating for photosynthesis (indicated by μDw). Starch reserves were largely depleted, and the C/N ratio decreased during this period.
FUNGAL CONTROL OF POPULATION CHANGES OF THE PLANKTONIC DIATOM ASTERIONELLA FORMOSA IN A SHALLOW EUTROPHIC LAKE1
Authors: Kudoh Sakae , Tokahashi Masayuki 
Published: October 2004

ABSTRACTParasitic fungi infected an Asterionella formosa Hass. population for 10 months of the year, during which time the population density of the alga was over 100 cells‐L−1. High injection rates of more than 20% of the cells were observed between February and July except on a few occasions such as late April and late June. Mortality of infected diatom cells was temperature dependent in dialysis tube culture experiments; the loss rate of field populations due to fungal injection also was affected by temperature. Loss rates of diatom cells were negligibly small m February even though infection percentages were more than 20%, but increased toward summer with an increase m temperature. High infection percentages and correspondingly high loss rates (e.g. 0.3 d−1) occurred periodically during the summer. The results suggest that this type of host‐parasite interaction is an important control of algal population size in natural waters.
STRUCTURE AND CHEMISTRY OF A NEW CHEMICAL RACE OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE) THAT PRODUCES LYCOPADIENE, A TETRATERPENOID HYDROCARBON1
Authors: Metzger Pierre , Allard Béatrice , Casadevall Eliette , Berkaloff Claire , Couté Alain 
Published: October 2004

ABSTRACTNew strains of the hydrocarbon rich alga Botryococcus braunii Kützing were isolated from water samples collected in three tropical freshwater lakes. These strains synthesize lycopadiene, a tetraterpenoid metabolite, as their sole hydrocarbon. The morphological and ultrastructural characteristics of these algae are similar to those reported for previously described strains which produce either alkadienes or botryococcenes. The pyriform shaped cells are embedded in a colonial matrix formed by layers of closely appressed external walls: this dense matrix is impregnated by the hydrocarbon and some other lipids. We believe the new strains synthesizing lycopadiene form a third chemical race in B. braunii, besides the alkadiene and botryococcene races, rather than a different species. Like the other two types of hydrocarbons, lycopadiene was produced primarily during the exponential and linear growth phases. The major fatty acid in the three races was oleic acid. This fatty acid was predominant in the alkadiene race; palmitic and octacosenoic acid also were present in appreciable amounts in the three races. Cholest‐5‐en‐3β‐ol, 24‐methylcholest‐5‐en‐3β‐ol and 24‐ethylcho‐lest‐5‐en‐3β‐ol occurred in the three races; three unidentified sterols also were detected in the lycopadiene race. Moreover, the presence of very long chain alkenyl‐phenols in the lipids of algae of the alkadiene race was not observed in the botryococcene and lycopadiene races. Of the polysaccharides released in the medium, galactose appeared as a primary component: it predominated in the botryococcene race. The other major constituents were fucose for the alkadiene race and glucose and fucose for the lycopadiene race. Although morphologically similar, some important chemical differences exist among algae classified as B. braunii.
PHYSIOLOGICAL VARIABILITY WITHIN TEN STRAINS OF CHAETOCEROS MUELLERI (BACILLARIOPHYCEAE)1
Authors: Johansen Jeffrey R. , Barclay William R. , Nagle Nicholas 
Published: October 2004

ABSTRACTThe effects of temperature, ionic composition, and conductivity on growth rates of ten strains of Chaetoceros muelleri Lemmerman (mostly var. subsalsum Johan. & Rushf.) were studied. Lipid content of stressed and unstressed cells and fatty acid composition were also determined. Considerable physiological variability was observed in the ten strains, although principal components analysis of physiological data indicated that all strains fell into one of two major groups: C. muelleri (var. muelleri and var. subsalsum) and an undescribed Chaetoceros species morphologically close to C. muelleri var. subsalsum. A high degree of agreement was found among morphological, physiological, and biochemical data sets, indicating that physiological and biochemical data may be helpful in making taxonomic decisions in diatoms, particularly in taxa with few morphological characters. We also conclude that nonmorphological characters such as those employed in the present study can be used to test phylogenetic hypotheses formulated from traditional morphological data.
BIOCHEMICAL COMPOSITION AND METABOLIC ACTIVITY OF SCRIPPSIELLA TROCHOIDEA (DINOPHYCEAE) RESTING CYSTS1
Authors: Binder Bruin J. , Anderson Donald M. 
Published: October 2004

ABSTRACTThe composition and metabolic activity of cysts of the marine dinoflagellate Scrippsiella trochoidea (Stein) Loeblich were examined during dormancy, quiescence, and germination. On a per cell basis, newly formed cysts contained an order of magnitude more carbohydrate but significantly less protein and chlorophyll a than did exponentially growing vegetative cells. Loss of lipid and carbohydrate from cysts during the initial dormancy period reflected a respiration rate estimated to be 10% of the respiratory activity in vegetative cells. Among older, quiescent cysts the calculated respiration rate decreased further to approximately 1.5% of the vegetative rate and appeared to proceed largely at the expense of carbohydrate reserves. These estimated rates of respiration were in good agreement with direct measurements of cyst oxygen consumption. The transfer of quiescent cysts to conditions permissive for germination resulted in a rapid increase in respiration rate, as evidenced by carbohydrate loss and O2 consumption. The increased respiratory activity was followed by an increase in protein content and, later, by an increase in chlorophyll a content and photosynthetic capacity. Just prior to germination the P/R ratio became greater than 1, and the estimated chlorophyll‐specific photosynthetic activity reached 75% of the rate in vegetative cells. Complete restoration of photosynthetic and respiratory capacity apparently was not achieved until after excystment. These data confirm the common assumption that dinoflagellate cysts represent true “resting” cells, containing extensive energy reserves and displaying greatly reduced metabolic activity.
CARBON FIXATION IN CULTURED MARINE BENTHIC DIATOMS1
Authors: Zimba Paul V. , Sullivan Michael J. , Glover Hilary E. 
Published: October 2004

ABSTRACTThe enzyme activity of ribulose 1, 5‐bisphosphate carboxylase‐oxygenase (RuBisCO) and phosphoenolpyruvate carboxylase (PEPC) was measured in four species of marine benthic diatoms isolated from subtidal sediments of Graveline Bayou, Mississippi. Enzyme activities were measured in cultures of Amphora micrometra Giffen, A. tenerrima Aleem and Hustedt, Nitzschia fontifuga Cholnoky, and Nitzschia vermicularis Grunow that were grown at light levels supporting μmax and at light‐limiting irradiances. All four species exhibited similar RuBisCO: PEP ratios (range = 1–1.8) at μmax the lowest ratio (0.4) was observed in A. micrometra. Reduced light levels increased PEPC relative to that measured at μmax in two species.Two‐dimensional paper chromatography was used to determine the first products of carbon fixation in A. micrometra After a 15 s incorporation period, the first product of photosynthetic carbon fixation was 3‐phosphoglycerate even though this alga had a PEPC activity that was three times higher than that of RuBisCO. After 30 s, over 50% of the recovered radioactivity was still in this compound. Stable carbon isotope analyses of a mixture of the four pennate diatoms also suggest the predominant carbon fixation pathway in these benthic diatoms was similar to C3 plants.
TWO CLASS I ALDOLASES IN KLEBSORMIDIUM FLACCIDUM (CHAROPHYCEAE): AN EVOLUTIONARY LINK FROM CHLOROPHYTES TO HIGHER PLANTS1
Authors: Jacobshagen Sigrid , Schnarrenberger Claus 
Published: October 2004

ABSTRACTTwo fructose‐bisphosphate aldolases(EC 4.1.2.13) from Klebsormidium flaccidum Silver, Mattox and Black‐well were purified by affinity elution from phosphocellulose. The two enzymes were subsequently separated by HPLC on an anion‐exchange column (QAE‐silica). The aldolase eluting first represented 5% of the total activity; the other aldolase represented the remaining activity. The activity of the enzymes was not reduced by the presence of 1 mM EDTA or increased by 0.1 mM Zn2+, establishing their character as class I type (Me2+ independent) aldolases. The Km(fructose‐1,6‐bisphosphate) values were 1.7 and 34.7 μM for the enzyme eluting first and second, respectively, from the QAE‐silica column. The subunit molecular masses, as determined by SDS‐PACE, were 40.5 and 37 kD; the specific activities of the purified enzymes were 7.9 and 24.7 · mg−1 protein, respectively. The two aldolases of K. flaccidum are homologous to the cytosol and chloroplast specific isoenzymes of higher plants by several criteria and are therefore probably located in the same cellular compartments in K. flaccidum. The Km and specific activity for the chloroplast aldolase of K. flaccidum are three times higher than for the chloroplast aldolase of higher plants, a remarkable difference. Immunotitration with specific antisera against the chloroplast aldolase of Chlamydomonas reinhardtii Dangeard and spinach showed that the chloroplast aldolase of K. flaccidum was immunochemically intermediate in structure to the respective aldolases of C. reinhardtii and higher plants. K. flaccidum is the second species of Charophyceae (besides Chara foetida Braun) with two class I aldolases as in higher plants whereas two species of Chlorophyceae have only one class I aldolase and, under some conditions, an additional class II (Me2+ dependent) aldolase. Thus, aldolases may turn out, in addition to the known enzymes of glycolate conversion and urea degradation, be a novel enzyme system to evaluate algal evolution along with cytological features.