bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHLOROPLAST STRUCTURE IN THE CHLOROMONADOPHYCEAN ALGAVACUOLARIA VIRESCENS1
Authors: Heywood Peter 
Published: August 2007

ABSTRACTThe chloroplasts ofVacuolaria virescensCienkowsky are present in large numbers between the cell membrane and the layer of cytoplasm surrounding the nucleus; they are disc‐shaped structuresca.3–4 μM long by 2–3 μM wide. Chloroplast bands consist of 3 opposed thylakoids with adjacent bands frequently interconnected. External to the girdle band is a chloroplast envelope separated from the cytoplasm by endoplasmic reticulum; there is no immediately apparent continuity between this endoplasmic reticulum and the nuclear envelope. Small electron‐dense spheres in the chloroplast stroma are thought to be lipid food reserve. Eyespots and pyrenoids are absent.
POST‐PLEISTOCENE DIATOM SUCCESSION IN DOUGLAS LAKE, MICHIGAN1,2
Authors: Stoermer E. F. 
Published: August 2007

ABSTRACTAnalysis of fossil diatom assemblages recovered from a 12.2 m core reveals a series of distinct floristic associations. The associations present are correlated with sediment type and reflect successive stages in the development of the lake. A basal red clay sediment contains a planktonic association characteristic of large, proglacial lakes. At 10.0 m core depth, sediment type changes to fine sand containing a higher abundance of benthic species indicating reduction of water depth at the deposition site. Marl sediments begin at 9.7 m and contain an association characteristic of a small, shallow, oligotrophic lake. At 8.8 m the marl sequence is interrupted by highly organic sediment containing a eutrophic plankton association. From 8.5 to 7.6 m the sediment type grades from marl to organic, apparently reduced sediments and diatom associations present contain successively higher percentages of planktonic species associated with eutrophic habitats. By the 7.6 m level a eutrophic plankton association, similar to the modern flora, is established and remains remarkably constant to the surface of the section.
STUDIES ON THE AUTECOLOGY OF THE MARINE DIATOM THALASSIOSIRA NORDENSKIOELDII. II. THE INFLUENCE OF CELL SIZE ON GROWTH RATE, AND CARBON, NITROGEN, CHLOROPHYLL a AND SILICA CONTENT1
Authors: Durbin Edward G. 
Published: August 2007

ABSTRACTThe effect of cell size on growth rates and some cellular contents of Thalassiosira nordenskioeldii Cleve has been measured at 0 and 10 C. At 0 C the growth rate did not vary with cell size. The 2 smallest clones at this temperature had reduced growth rates because of the induction of sexuality in that size range. The clones grown at 10 C showed a significant negative relationship between growth rate and valve diameter with the cell surface area/volume ratio positively related to growth rate. At both temperatures the smaller cells had proportionately more carbon and nitrogen/unit cell volume. The amount of chlorophyll a and silica/unit cell surface area increased with increasing cell surface area at both 0 and 10 C. Both the C/N and C/chl a ratios showed no significant change with cell size at either temperature but there was a significant increase in the C/chl a ratio at 0 C. The C/Si ratio decreased with increasing cell size at both 0 and 10 C.
PHYSIOLOGICAL INVESTIGATIONS ONALARIA ESCULENTA(LAMINARIALES, PHAEOPHYCEAE). II. ROLE OF TRANSLOCATION IN BLADE GROWTH1,2
Authors: Buggeln Richard G. 
Published: August 2007

ABSTRACTLaboratory studies on blade growth inAlaria esculenta(L.) Grev. showed 3 periods of rapid blade elongation during the year: October–November, February–April and late June. The first two periods are characteristic of many Laminariales; the unique June peak may reflect local nutrient conditions. While the distal blade functions as a source, supplying organic matter to the blade meristem, the stipe can be a source during periods of rapid growth or a sink during late summer when blade growth is slow. Maximum enhancement of elongation rate of blade meristems was observed in 40–50 cm blades; longer blades showed no further increase in growth rate. This blade length‐growth promotion relationship may be independent of seasonal variations in meristematic activity.14C tracer experiments suggested that separate growth promotion effects by distal blade, sporophylls and stipe were not additive in the intact thallus. The preferential source of assimilate for blade meristem growth was the distal blade. Secondary sources: sporophylls, which were activated following excision of the primary source; and stipe, which began to translocate assimilate when both sources were removed. The role of secondary sources in nature is discussed. Profiles of radioactivity in alcohol‐soluble organic matter in blades are evaluated in relation to tracer profiles in higher plants and mechanisms of translocation.
MATURATION OF ALGAL ZYGOTES: ALTERNATIVE EXPERIMENTAL APPROACHES FOR CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE)1
Authors: Van Winkle‐Swift Karen P. 
Published: August 2007

ABSTRACTYoung zygotes from crosses of Chlamydomonas reinhardtii Dang. mutant and wild‐type strains were incubated, in the presence or absence of light and/or nitrogen to determine whether continuation of conditions inducing gamete formation permits zygospore formation without loss of viability. Different culture media, continuous illumination vs. dark incubation and various durations of the maturation period were tested, for effect on zygospore germination efficiency, zygospore “burst size” and zoospore viability. Following either the routine maturation procedure of dark incubation on standard minimal medium, or following a new procedure of incubation under continuous illumination on N‐free medium, zygospore formation can be ensured and high germination efficiencies obtained within 3 days after mating. Tetrad analysis indicates meiosis occurs normally whether zygotes have been matured in the presence or absence of light or nitrogen. Preliminary data suggest an effect of increased maturation time on the transmission of cytoplasmic genes, if a N‐free continuous illumination maturation protocol is followed. Two experimental approaches for the maturation of C. reinhardtii zygotes are suggested and advantages of each are discussed.
STARRIA ZIMBABWEËNSIS (CYANOPHYCEAE) GEN. NOV. ET SP. NOV.: A FILAMENT TRIRADIATE IN TRANVERSE SECTION1
Authors: Lang Norma J. 
Published: August 2007

ABSTRACTA new filamentous bluegreen alga Starria zimbabweënsis gen. nov. et sp. nov. isolated from a soil sample collected near Zimbabwe, Southern Rhodesia, has a unique triradiate morphology. In transverse section each narrow cell possesses three arm‐like projections, separated by 120° and in which pigment is concentrated. Filaments may be straight or twisted and various clonable biradiate forms have originated in cultures initiated from the triradiate type. Cell ultra‐structure is typical of the Oscillatoriaceae except that 70 nm pit‐like pores occur throughout the L‐II layer of the longitudinal walls. Wall structure of deviant forms is identical to that of the triradiate “wild type.” The organism is assigned to the Oscillatoriaceae rather than to the Gomontiellaceae or to a new family.
ULTRASTRUCTURE OF CYST FORMATION IN OCHROMONAS TUBERCULATA (CHRYSOPHYCEAE)1
Authors: Hibberd David J. 
Published: August 2007

ABSTRACTThe cysts (statospores) of Ochromonas tuberculata Hibberd are produced within a cytoplasmic silica deposition vesicle (SDV) whose membrane (silicalemma) appears to be formed by the coalescence of golgi vesicles. Silica is first deposited as small nodules and the collar and spines develop by centrifugal growth only after a complete but still thin wall has been laid down. Small vesicles appear to be attached to the SDV only in the region overlying the developing collar; a cap of radially arranged, moderately electron‐dense material occurs at the tip of the growing spines. The cyst pore is formed at the anterior end of the flagellate cell, by lack of silica deposition over a small region of the SDV and rupture of the SDV and other membranes crossing this region. When the cyst wall is complete, an extracystic plug is formed in the pore, resulting in the loss of some extracystic cytoplasm and the plasmalemma, and the inner SDV membrane becomes the functional plasmalemma. The plug develops first by coalescence with the cell membrane of golgi‐derived vesicles containing dense but apparently nonsiliceous spicules surrounded by amorphous material. During later stages of plug formation only fibrous material is deposited, some of which may be extruded through the pore forcing out some of the spiculate component. Scanning electron micrographs of the mature wall show it is smooth except for the concentrically wrinkled inner face of the flared collar and that the real pore diameter is only ca. half that of the collar. At germination the plug completely disappears in an unknown way and a single cell, similar to a normal vegetative cell emerges through the pore. Chrysophycean cyst formation generally resembles cell wall formation in diatoms, but differs in some details.
DEVELOPMENT OF MUCILAGINOUS SURFACES IN EUGLENOIDS. II. FLAGELLATED, CREEPING AND PALMELLOID CELLS OFEUGLENA1
Authors: Rosowski James R. 
Published: August 2007

ABSTRACTCritical‐point dried (CPD) cells from clonal cultures ofEuglena gracilisKlebs (Z strain),E. desesEhrb.,E. tripteris(Duj.) Klebs andE. myxocylindraceaBold & MacEntee were examined by scanning electron microscopy. Flagellated motile cells ofE. gracilisare naked except for a few strands of mucilage on the posterior tip. Flagellated cells ofE. tripterishave a permanent mucilage coating often of uneven distribution and usually not as well developed as that of nonflagellated creeping cells which have a distinctive mucilage. InE. desesthe coating appears rough due to the aggregation of isolated groups of strands above the cell surface. InE. tripteristhe coating appears smooth except for breaks near the articulation of the pellicular strips where the mucilage may rise above the surface to form waves. At high magnification this mucilage consists of a network of strands generally lying parallel to the cell surface; the strands become obscure in some specimens. InE. myxocylindraceaelongated, mucilage‐coated cells contract to form spheres which undergo further mucilage deposition producing the mucilage covering of palmellae. As palmellae mature, the mucilage surface becomes less porous and the individuality of most mucilage strands is lost.
COMPARISONS OF SALT‐MARSH FUCOID PRODUCTION ESTIMATED FROM THREE DIFFERENT INDICES1
Authors: Brinkhuis B. H. 
Published: August 2007

ABSTRACTProduction of Ascophyllum nodosum (L.) LeJolis ecads and Fuscus vesiculosus L. was calculated from measurements of in situ growth, seasonal variations in standing‐crops and seasonal variations in photosynthetic capacity. A computer model for predicting daily, monthly and yearly net production from photosynthesis data was constructed. This model used daily irradiation, actual biomass of algae/m2 contributing to production and photosynthesis vs. light intensity relationships as data inputs. Comparison of production estimated from in situ growth, standing‐crops and photosynthesis indicated that both marsh fucoids turn over biomass twice per year. Total net production of both fucoids, estimated from photosynthesis data, was ca. 315 g C · m−2· yr−1. On the other hand, production of both fucoids calculated from standing‐crop data was only 155 g C · m−2· yr−1.
INFLUENCE OF NITROGEN SOURCE ON MORPHOLOGY OF RIVULARIACEAE (CYANOPHYTA)1
Authors: Sinclair Christine , Whitton Brian A. 
Published: August 2007

ABSTRACTThirty‐four heterocyst‐producing strains of Rivulariaceae (29 Calothrix, 1 Dichothrix, 2 Gloeotrichia, 2 Rivularia), which produced tapered trichomes in medium minus combined nitrogen, were grown in the presence of nitrate. One strain was unchanged in morphology under this condition. The remaining 33 strains developed trichomes lacking heterocysts. In 19 strains almost all the trichomes became untapered and in the other 14, similar untapered trichomes were produced, but also many tapered trichomes resembling Homoeothrix or Hammatoidea. Similar results were obtained when representative strains were incubated with ammonia as the source of combined N. Only five strains formed colorless hairs in the control medium (minus combined N). The presence of combined N did not diminish hair development in the two strains which had only a few short hairs, but hair frequency and length were both reduced considerably in the three strains with many long hairs in the control medium. Two strains of the non‐heterocystous genus Homoeothrix were incubated in medium without combined N. Neither strain showed any growth or heterocyst development, indicating that neither is simply a growth form of a heterocystous genus.
STORAGE AND STRUCTURAL PRODUCTS FORMED DURING PHOTOSYNTHESIS IN THE SIPHONOUS ALGA CAULERPA SIMPLICIUSCULA(CHLOROPHYCEAE)1
Authors: Howard Russell John , Grant Bruce Raymond , Fock Heinrich 
Published: August 2007

ABSTRACTThe distribution of radioactivity into storage and intermediary metabolites during photosynthesis over periods of up to three hours was followed in the siphonous green alga Caulerpa simpliciuscula C. Ag. After the first hour, almost all the carbon assimilated was recovered as insoluble 1,4‐α‐glucan. There was rapid movement of carbon into insoluble 1,3‐β‐glucans during the first 20 min of photosynthesis, but little additional carbon moved into these compounds after that time. This contrasted with the movement of carbon into the soluble 1,3‐β‐glucan fraction, which continued for 2 h. Sucrose accumulated very little 14C during the entire period of photosynthesis. There was a very slow transfer of 14C into lipid throughout the period but the rate was linear. Protein labelling showed a lag of 2 h before it reached the same rate of 14C accumulation as shown by the lipid initially. It is suggested that the distribution of radioactivity can be explained in part by proposing that the tissue is in the latter stages of recovery from the wounding which look place at the time of dividing the thallus into sections.
ALCIAN BLUE: A QUANTITATIVE AQUEOUS ASSAY FOR ALGAL ACID AND SULFATED POLYSACCHARIDES1
Authors: Ramus J. 
Published: August 2007

ABSTRACTAlcian Blue, a cationic copper phthalocyanine dye, complexes with the anionic carboxyl and half‐ester sulfate groups of acidic algal polysaccharide in aqueous solution to form an insoluble precipitate. The quantity of dye removed from solution is proportional to the quantity of polyanion in solution, and this principle forms the basis for the quantitative determination of acid and/or sulfated algal polysaccharides. The assay is linear between 0 and 100 μg/ml agar, alginic acid, carrageenan, pectin and Porphyridium aerugineum Geit. polysaccharide. In addition, the technique is used to determine the anion density of acid polysaccharides on a molar or weight equivalency basis.
PIGMENTS OF THE DINOFLAGELLATE PERIDINIUM BALTICUM AND ITS PHOTOSYNTHETIC ENDOSYMBIONT1
Authors: Withers Nancy W. , Cox Elenor R. , Tomas Ronald , Haxo Francis T. 
Published: August 2007

ABSTRACTAn examination of the pigments of the binucleate dinoflagellate Peridinium balticum (Levander) Lemmerman revealed the presence of chlorophylls a, c1 and c2 and the carotenoids: fucoxanthin (most abundant), diadinoxanthin, diatoxanthin, an unidentified fucoxanthin‐like xanthophyll, β‐carotene, γ‐carotene and astaxanthin. A comparison of the pigments of P. balticum and P. foliaceum (Stein) Biecheler, also a binucleate dinoflagellate, demonstrated similar compositions. However P. balticum lacked the β‐carotene precursors (e.g. phytoene) which accumulated outside the chloroplast in P. foliaceum. This study indicates that P. balticum and P. foliaceum are closely related; each species is a heterotrophic dinoflagellate with a photosynthetic endosymbiont taxonomically affiliated with the Chrysophyta (Chrysophyceae or Bacillariophyceae).
COLONY DEVELOPMENT INEUDORINA ELEGANS(CHLOROPHYTA, VOLVOCALES)1
Authors: Gottlieb Bruce , Goldstein Melvin E. 
Published: August 2007

ABSTRACTA detailed ultrastructure study was made of cell division and colony development inEudorina elegansEhrenberg. At the onset of cell division and prior to nuclear division the nucleus moved from the cell center to the cell surface. During nuclear division the nuclear membrane remained intact, except for openings occurring at the nuclear poles. The spindle microtubules appeared to arise from a MTOC‐like (microtubule organizing centers) structure, while centrioles were absent from the nuclear poles. Following telophase, daughter nuclei formed which were separated by several distinct bands of endoplasmic reticulum. Cytokinesis occurred with formation of a cleavage furrow, associated with a typical phycoplast band of microtubules. However, cytokinesis was incomplete, resulting in formation of cytoplasmic bridges between the plakeal cells. Upon completion of up to five successive cell divisions, the plakea underwent inversion, which appeared to involve the production of colonial envelope material and rearrangement of cytoplasmic bridges. A new hypothesis concerning inversion is postulated based on these observations.
A CULTURE STUDY OF SALINITY RESPONSES IN ECOTYPES OF TWO ESTUARINE RED ALGAE1
Authors: Yarish Charles , Edwards Peter , Casey And Stephen 
Published: August 2007

ABSTRACTLaboratory culture studies on the euryhalinity of Bostrychia radicans Montagne and Caloglossa leprieurii (Montagne) J. Agardh from the mouth and head of the Mullica River estuary, New Jersey, revealed both species probably have ecotypes whose growth patterns correlate with the salinity regime of their habitat in nature. Significant growth differences of tetrasporelings were determined in response to four salinities (5, 15, 25, 35%c) even after acclimation periods of the tetrasporophytes from 6 mo–2 yr in laboratory culture. However, one isolate of Bostrychia and both isolates of Caloglossa also demonstrated some capability for physiological adaptation to salinity changes although this was less significant statistically than their ecotypic response. It thus appears that certain euryhaline algae may consist of ecotypes, each of which has some capacity for physiological adaptation to salinity variations.
VOLATILE ORGANIC SULFIDES FROM FRESHWATER ALGAE1
Authors: Bechard Marc J. , Rayburn William R. 
Published: August 2007

ABSTRACTDimethyl sulfide (DMS) was found to be the principle biogenic sulfur compound in a freshwater environment. Endemic and non‐endemic algae were cultured under axenic and nonaxenic conditions in defined media. Sulfur gas analysis of culture fluids indicated that members of the Cyanophyta were probable sources of DMS whereas representatives of the divisions Chlorophyta, Xanthophyta and Bacillariophyta apparently did not produce this compound. Comparison of gaseous contents of young and old nonaxenic cultures of filamentous algae in the divisions Chlorophyta and Xanthophyta showed DMS occurred only in aged cultures and was probably produced by bacteria utilizing substances from senescent algal cells. Data suggest that the composition of the algal community determines whether DMS is algal and/or bacterial in origin.
DIEL CHANGES IN PHASED‐DIVIDING CULTURES OF CERATIUM FURCA (DINOPHYCEAE): NUCLEOTIDE TRIPHOSPHATES, ADENYLATE ENERGY CHARGE, CELL CARBON, AND PATTERNS OF VERTICAL MIGRATION1
Authors: Weiler Caroline S. , Karl David M. 
Published: August 2007

ABSTRACTThe diel pattern of cell division, cell carbon, adenine nucleotides and vertical migration was determined for laboratory cultures of the photosynthetic marine dinoflagellate, Ceratium furca (Ehr.) Clap. & Lachm., entrained on an alternating 12:12 LD schedule at 20 C. Cell division was initiated during the latter portion of the dark period with ca. 30% of the population undergoing division. Cell C increased during the light period and exhibited a linear decrease with a loss of 33% during the dark period. ATP · cell−1 increased during the light period and decreased by ca. 40–50% during the dark period. The diel patterns of cell C and ATP tended to “buffer” the magnitude of the change in C:ATP ratios around an overall mean value of 89. There was no obvious trend in the concentration of [GTP + UTP] · cell−1 over the cell cycle. The cellular adenylate energy charge was maintained at values between 0.8 to 0.9 throughout the 24 h LD cycle, despite a ca. 40% decrease in total adenylates (AT= ATP + ADP + AMP) during the dark period on 12:12 LD, and over a 68% decrease in ATP during 42 h of continuous darkness. These data lend experimental support to the theory of cellular metabolic control by the adenine nucleotides. With lateral illumination on 12:12 LD cycles, the cells began to concentrate at the surface of the experimental tubes shortly before the lights were turned on, and at the bottom of the tubes shortly before the lights were extinguished. This pattern continued for 6 days in continuous darkness, suggesting that the vertical migration pattern is independent of a phototactic response and may be under the control of an endogenous rhythm.
VITAMIN B12‐BINDER AND OTHER ALGAL INHIBITORS1
Authors: Pintner Irma J. , Altmeyer Vicki L. 
Published: August 2007

ABSTRACTEuglena gracilisKlebs,Poterioochromonas malhamensis(Pringsheim) Peterfi,Monochrysis lutheriDroop,Isochrysis galbanaParke andPhaeodactylum tricornutumBohlin are known to release into the medium a substance which binds free vitamin B12. The binder, apparently a glycoprotein, makes vitamin B12unavailable and inhibits growth of vitamin B12‐requiring microorganisms. Culture filtrates of selected marine diatoms, chrysophytes, cryptophytes, dinoflagellates and green algae contained the binder, indicating that binder release was not restricted to any algal group. However the three prokaryotic bluegreens tested do not produce B12‐binder. Production is also independent of the nutritional requirements of the donor, being produced by autotrophs and auxotrophs. The binders produced by these marine species have similar properties: they are heat labile; inhibition is not species‐specific; it is competitive, being reversed by adding B12. Production increases with density of the culture and is not restricted to stationary or scenescent cells. The marine species tested produced much less B12than the freshwaterEuglenaandPoterioochromonas;the inhibition is reversed by 20–50 ng · 1−1of B12for marine species which reach moderate densities and by 150–300 ng · 1−1B12for the densely growing species. Consequently the binder may affect the growth of B12‐requiring species only in environments like the open ocean poor in B12. By contrast, the marine algae produce other inhibitors which are often heat stable and very inhibitory. These inhibitors, being species‐specific and less labile, may be more important in affecting the succession of algal species in natural waters.
EFFECTS OF ARSENIC SPECIATION AND PHOSPHATE CONCENTRATION ON ARSENIC INHIBITION OF SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)1
Authors: Sanders James G. 
Published: August 2007

ABSTRACTArsenate is taken up readily by Skeletonema costatum (Greville) Cleve due to its chemical similarity to phosphate, and it inhibits primary productivity at concentrations as low as 67 nM when the phosphate concentration is low. A phosphate enrichment of greater than 0.3 μM alleviates this inhibition; however, the arsenate stress causes an increase in the cell's requirement for phosphorus. Arsenite is also toxic to Skeletonema at similar concentrations. Methylated species, such as dimethylarsinic acid, did not affect cell productivity at the levels examined. Thus, the reduction and methylation of arsenate to dimethylarsinic acid by the cell produces a stable, non‐toxic compound.