bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHARACTERISTICS OF SEXUAL AND ASEXUAL RESTING CYST (STATOSPORE) FORMATION IN DINOBRYON CYLINDRICUM IMHOF (CHRYSOPHYTA)1
Authors: Sandgren Craig D. 
Published: August 2007

ABSTRACTThe reproductive significance of siliceous cysts (statospores) produced by the common vernal chrysophyte Dinobryon cylindricum Imhof has been investigated under defined culture conditions. Three types of statospores have thus far been induced in culture: 1) uninucleate, asexual; 2) binucleate, asexual (potentially autogamic); 3) binucleate, sexual (zygotic). The production of each type of cyst responds differently to an array of nutrient deficiencies (P, N, vitamins, micrometals). An individual clone may be capable of participating in the production of all or only a subset of these types of resting cysts. All D. cylindricum statospores are morphologically identical regardless of their reproductive significance. Sexual reproduction leading to zygotic statospore formation is anisogamous, heterothallic, and involves a gametogenic hormone (erogen) that is apparently continuously released from female clones. Only a single bipolar mating group is documented here and clonal compatibility varies considerably within the mating group.The dynamics of encystment for each type of statospore has been determined relative to the growth of the vegetative cell population. Statospores may be produced either during the exponential phase (intrinsic encystment) or stationary phase (extrinsic encystment) of culture growth depending on the clones involved. The effect of both asexual and sexual resting cyst production on the net growth rate and dynamics of natural chrysophyte populations is discussed. Statospores appear to represent a more flexible reproductive strategy than the resistant zygospores produced by the other common groups of planktonic microalgae.
ULTRASTRUCTURE OF ACTIVE AND RESTING COLONIES OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE)1
Authors: Wolf Fred R. , Cox Elenor R. 
Published: August 2007

ABSTRACTThe ultrastructure of resting state colonies of Botryococcus braunii Kützing from two localities is compared to active state colonies maintained in the laboratory. Qualitative hydrocarbon analyses confirmed the physiological status of each sample according to the precedent in the literature; resting state colonies contained botryococcenes, while active state colonies contained a predominance of straight‐chain olefins. The ultrastructure of resting and active state colonies is fundamentally similar. The chloroplast of resting state cells contains fewer thylakoids and larger relative numbers of plastoglobuli than the chloroplast of active state cells maintained under favorable growth conditions. Previously undescribed phenomena include the cytochemical demonstration of polyphosphate bodies microbody‐like organelles and ER‐ribosomal‐mitochondrial complexes.Attempts to elicit the transition of active to resting state colonies utilizing different light intensities and/or nitrogen deficient media were unsuccessful. Instead, these experiments induced the formation of yellow or whitish‐brown senescent colonies which always contained a predominance of olefins. Senescent cells contain reduced, peripherally displaced organelles. Most of the cytoplasm is occupied by vacuoles and lipid (probably hydrocarbon) inclusions. Morphologically identifiable polyphosphate bodies are usually small or absent. Observations pertinent to the mechanism of hydrocarbon secretion were in basic agreement with previously published information. The outer cell wall, or trilamellar structure (TLS), was recently as the primary site of hydrocarbon accumulation and production. The role of the TLS in hydrocarbon biosynthesis, however, should be cautiously regarded without additional evidence.
THE DISTRIBUTION OF EDAPHIC DIATOMS ALONG ENVIRONMENTAL GRADIENTS OF A LOUISIANA SALT MARSH1
Authors: Cook Lawrence L. , Whipple Stephen A. 
Published: August 2007

ABSTRACTEdaphic (sediment‐associated) diatoms were collected from five sites along a gradient from slightly brackish to saline marsh on 30 November 1977 and 29 April 1978. Several environmental factors change along this gradient in addition to salinity, including tidal flushing and percent organic content of the soil. A total of 112 taxa were identified, with Amphora exigua Greg., Navicula phyllepta Kütz., N. salinarum Grun., and N. tripunctata (Müll.) Bory being among the five most abundant taxa on both sampling dates. The taxonomic composition of the diatom flora was very similar to those observed for other salt marshes located along the Gulf and Atlantic coasts. Diatom taxa were generally euryhaline and distributed continuously along the gradient from brackish to saline marsh. Species diversity (H1) and the number of taxa in a sample (S) were also similar to those reported for other North American salt marshes. The number of taxa in a sample was higher in the saline than in the brackish area on both sampling dates while species diversity was greater in the saline area only in April.
NITRATE AND PHOSPHATE UPTAKE INTERACTIONS IN A MARINE PRYMNESIOPHYTE1
Authors: Terry Kenneth L. 
Published: August 2007

ABSTRACTThe short‐ and long‐term uptake of nitrate and phosphate ions, and their interactions, were studied as functions of the preconditioning of Pavlova lutheri (Droop) Green. Populations were preconditioned in continuous culture at a variety of growth rates and N:P supply ratios. The maximum uptake rates cell−1 for nitrate and phosphate were of similar magnitudes, in spite of the forty‐fold smaller requirement for phosphorus. Short‐term phosphate uptake was independent of the nitrate concentration, but the short‐term nitrate uptake rate was reduced in the presence of phosphate. The severity of inhibition of nitrate uptake by phosphate was positively correlated with the preconditioning N:P supply ratio and the preconditioning growth rate. In response to large additions of nutrients, P. lutheri was able to increase its phosphorus content sixty‐fold, but was only able to take up enough nitrate to double its nitrogen content. The high rate of phosphate uptake relative to its requirement, the inhibition of nitrate uptake by phosphate, and the large capacity for phosphorus storage relative to its requirement, all of which were observed even under N limitation, may imply that even where nitrogen is limiting there can be interspecific competition for available phosphate.
COLONIZATION AND SUCCESSION OF ALGAE AND SOIL‐ALGAL INTERACTIONS ASSOCIATED WITH DISTURBED AREAS1
Authors: Starks Thomas L. , Shubert L. Elliot 
Published: August 2007

ABSTRACTThe number and abundance of algal species were not significantly different between non‐topsoiled areas and top‐soiled areas. Successional trends were evident at both sites, since the number of species and their abundance increased over time. Soil‐algal interactions were determined by regression analysis. A conceptual model was developed that illustrated the influence of soil chemical properties on algal abundance. Important factors affecting the soil algae were sodium, calcium, potassium, magnesium and certain trace elements. The possible influence of these factors on algal growth is discussed.
AUTECOLOGY OF AN ULTRAPLANKTONIC SHADE ALGA IN LAKE TAHOE2
Authors: Vincent Warwick F. 
Published: August 2007

ABSTRACTThe ultraplanktonic green alga Monoraphidium contortum Korm. in Lake Tahoe (California‐Nevada) demonstrated several ecological and physiological attributes of a genetically adapted shade species. Monoraphidium contortum achieved maximum biomass during deep mixing in winter when light availability was at a minimum. During stratification it was found in maximum abundance in the deep euphotic region, 100–150 m. This species was also distributed through the deep aphotic zone where, despite prolonged darkness, it remained capable of immediate photosynthesis when re‐exposed to light levels in the euphotic zone. The spirally twisted cells were grazed by two calanoid copepods in Lake Tahoe as readily as much larger‐celled phytoplankton species of less complex morphology. Slow growth rates in combination with high susceptibility to copepod grazing may effectively exclude M. contortum from the upper 75 m, where it was rarely recorded. In culture it showed a marked incapacity to adjust to ‘sun’ conditions but was well adapted to low light regimes. Under a wide range of irradiances, photochemical capacity, photosynthetic capacity and growth rates were low, but cellular pigment content remained high. The ratio of Pmax to respiration was at the lower end of the range for shade plants. Genetically distinct sun and shade populations of phytoplankton may play a determining role in major shifts of community structure over depth and time in Lake Tahoe.
ADAPTATION OF CERATIUM FURCA AND GONYAULAX POLYEDRA (DINOPHYCEACE) TO DIFFERENT TEMPERATURES AND IRRADIANCES: GROWTH RATES AND CELL VOLUMES1
Authors: Meeson Blanche W. , Sweeney Beatrice M. 
Published: August 2007

ABSTRACTGrowth rates and cell volumes of Ceratium furca Ehrenberg and Gonyaulax polyedra Stein were determined during the log phase of growth in cultures which had been extensively adapted to one of three temperatures and five irradiances. At each temperature, curves for the growth rate vs. irradiance for both species had light‐limited and light‐saturated regions. Three properties of these curves characterized the response of each species to temperature: the light‐saturated growth rate, the irradiance at which growth became light‐saturated and the compensation irradiance for growth. For both species, the first two properties generally decreased with declining growth temperature, while the compensation irradiance declined for Ceratium but had a V‐shaped response pattern for Gonyaulax. The light‐saturated growth rates were generally higher for Ceratium than for Gonyaulax, while the irradiance at which growth became saturated and the compensation irradiance were lower for Ceratium. The changes in cell volume associated with the irradiance and temperature of growth were very different for Ceratium and Gonyaulax. The cell size of Gonyaulax increased as irradiance and temperature decreased, while cell volumes of Ceratium did not change with temperature but were smallest at the highest and lowest growth irradiances. In general, the growth rate patterns were similar for Ceratium and Gonyaulax, while those for cell size were different. The maximum growth rate, the irradiance at which growth became saturated, the compensation irradiance, and the cell volume all showed that Ceratium grew at the same rate or faster than Gonyaulax over the entire range of irradiances and temperatures examined.
FACTORS CONTROLLING THE INTERTIDAL ZONATION OF IRIDAEA FLACCIDA (RHODOPHYTA)1
Authors: Foster Michael S. 
Published: August 2007

ABSTRACTField experiments were used to examine the effects of biological interactions on the abundance of Iridaea flaccida (S. & G.) Silva within and below its normal range in the intertidal zone of central California. A combination of competitor removal, grazer exclusion and transplant manipulations showed that within the I. flaccida zone, this alga can be the first macroscopic plant to become reestablished after clearing and that this can occur in less than two months. Grazing by molluscs within this zone retards, but does not prevent, re‐establishment. Although absent prior to the experiments, both I. flaccida and I. cordata (Turn.) Bory settled, grew rapidly and reproduced in cleared areas below the I. flaccida zone, regardless of the presence of grazers. These plants did not establish themselves if entire thalli or holdfasts of other algae normally occupying the lower zone were present. The results support the few other in situ experimental investigations of algal zonation by showing that, when bounded by other plants, the lower limits of intertidal algae are directly determined by competition. They also suggest that I. flaccida and I. cordata may be conspecific.
RESPONSE OF PROROCENTRUM MARIAE‐LEBOURIAE (DINOPHYCEAE) TO LIGHT OF DIFFERENT SPECTRAL QUALITIES AND IRRADIANCES: GROWTH AND PIGMENTATION1
Authors: Faust Maria A. , Sager John C. , Meeson Blanche W. 
Published: August 2007

ABSTRACTGrowth and pigment concentrations of the, estuarine dinoflagellate, Prorocentrum mariae‐lebouriae (Parke and Ballantine) comb. nov., were measured in cultures grown in white, blue, green and red radiation at three different irradiances. White irradiances (400–800 nm) were 13.4, 4.0 and 1.8 W · m−2 with photon flux densities of 58.7 ± 3.5, 17.4 ± 0.6 and 7.8 ± 0.3 μM quanta · m−2· s−1, respectively. All other spectral qualities had the same photon flux densities. Concentrations of chlorophyll a and chlorophyll c were inversely related to irradiance. A decrease of 7‐ to 8‐fold in photon flux density resulted in a 2‐fold increase in chlorophyll a and c and a 1.6‐ to 2.4‐fold increase in both peridinin and total carotenoid concentrations. Cells grown in green light contained 22 to 32% more peridinin per cell and exhibited 10 to 16% higher peridinin to chlorophyll a ratios than cells grown in white light. Growth decreased as a function of irradiance in white, green and red light grown cells but was the same at all blue light irradiances. Maximum growth rates occurred at 8 μM quanta · m−2· s−1 in blue light, while in red and white light maximum growth rates occurred at considerably higher photon flux densities (24 to 32 μM quanta · m−2· s−1). The fastest growth rates occurred in blue and red radiation. White radiation producing maximum growth was only as effective as red and blue light when the photon flux density in either the red or blue portion of the white light spectrum was equivalent to that of a red or of blue light treatment which produced maximum growth rates. These differences in growth and pigmentation indicate that P. mariae‐lebouriae responds to the spectral quality under which it is grown.
THE NORMAL AND INDUCED OCCURRENCE OF CYANOPHYCIN INCLUSION BODIES IN SEVERAL BLUE‐GREEN ALGAE1
Authors: Lawry Nelson H. , Simon Robert D. 
Published: August 2007

ABSTRACTMulti‐L‐arginyl‐poly(L‐aspartic acid) [arg‐poly(asp)], the polypeptide component of the cyanophycin inclusion body, is found in cells of many blue‐green algae. Formation of this material can be induced by a variety of treatments including the addition of excess nitrogen‐containing compounds, the addition of specific inhibitors of macromolecular synthesis, and the exclusion of sulfur or phosphorus. Knowledge of the conditions that induce the synthesis of this polypeptide has made possible an ultrastructural survey to determine the presence and cellular location of cyanophycin bodies in a variety of cyanobacteria. Data presented show that certain strains of the unicellular genus Synechococcus Nägeli do not contain arg‐poly(asp) under environmental conditions that markedly increase the level of such material in other cyanobacteria. In addition many strains show spatial localization of the cyanophycin bodies under normal growth conditions, and moreover the normal pattern is retained even when massive synthesis of arg‐poly(asp) is induced. Finally there is no evidence that these inclusion bodies occur in certain beggiatoan gliding bacteria.
ACROSYMPHYTON FIRMUM SP. NOV. (RHODOPHYTA, CRYPTONEMIALES), A NEW SUBTIDAL RED ALGA FROM NEW ZEALAND; DEVELOPMENTAL MORPHOLOGY AND DISTRIBUTION OF THE GAMETOPHYTE1
Authors: Hawkes Michael W. 
Published: August 2007

ABSTRACT Acrosymphyton firmum sp. nov., is described from the northeastern coast of North 1., New Zealand. Gametophytes are spring–summer annuals which grow subtidally on cobbles. Thalli are uniaxial; each axial cell bears a whorl of four indeterminate and one determinate branchlets. Indeterminate branchlets are alternately arranged giving the thallus a distichous and feather‐like appearance. Numerous corticating rhizoidal filaments are produced from the periaxial and lower whorl branchlet cells. These rhizoids entwine and obscure the main axis as the thallus develops until in the mature plant the axes have a firm consistency and lubricous texture. The carpogonial branch bearing short lateral filaments and auxiliary cell branch with terminal auxiliary cell place this new species in the genus Acrosymphyton Sjöstedt. Of the three described species in the genus, A. firmum is most similar to A. taylori. This is the first report of the genus Acrosymphyton and the only confirmed report of the family Dumontiaceae in New Zealand waters.
PHYSIOLOGY OF SEA ICE DIATOMS. I. RESPONSE OF THREE POLAR DIATOMS TO A SIMULATED SUMMER‐WINTER TRANSITION1
Authors: Palmisano Anna C. , Sullivan Cornelius W. 
Published: August 2007

ABSTRACTThree axenic polar sea ice diatom cultures were subjected to a 30 day simulated summer‐winter transition in which light and temperature were decreased and salinity was increased to mimic seasonal changes previously reported for ice‐covered polar seas. The diatoms responded to these changes by a reduction in cellular metabolism as indicated by: 1) A decline in growth rate and photosynthetic rate; 2) a decrease in cellular ATP; and 3) the storage and subsequent utilization of endogenous carbon reserves. In addition, heterotrophic potential of the three clones increased by as much as 60‐fold. In some cases, the decrease in light intensity characteristic of the onset of polar winter was alone sufficient to trigger these physiological changes.
ZINC ADSORPTION AND TRANSPORT BYCHLAMYDOMONAS VARUIABILISANDSCENEDESMUS SUBSPICATUS(CHLOROPHYCEAE) GROWN IN SEMICONTINUOUS CULTURE1
Authors: Bates Stephen S. , Tessier André , Campbell Peter G. C. , Buffle Jacques 
Published: August 2007

ABSTRACTThe amount of zinc adsorbed onto the cell surface of the unicellular green algaeScenedesmus subspicatusHodat andChlamydomonas variabilisDangeard was operationally defined by extraction with EDTA; it was a function of the concentration of free ionic zinc remaining in the growth medium, rather than that of the total (free plus complexed) zinc concentration, and could be described by Langmuir isotherms. Conditional adsorption equilibrium constants for zinc were 0.123 and 0.039 L ·μmol−1forS. subspicatusandC. variabilis, respectively. A portion of the zinc adsorbed ontoC. variabiliswas released into solution after 1 h of contact with the metal, providing a possible tolerance mechanism for this alga; the division rate ofC. variabiliswas not altered by up to 12 μmol Zn2+· L−1, although the cell yield obtained during the stationary phase was significantly decreased. The amount of transported or cellular zinc, for both algal species, was operationally defined as the zinc remaining with the cell after EDTA‐extraction; it was a linear function of the free ionic zinc concentration remaining in solution, suggesting that the zinc transported into the cell was not derived from the total adsorbed fraction, although the latter may contain some zinc originating from specific sites leading to zinc transport.
ACCUMULATION OF β‐CAROTENE IN HALOTOLERANT ALGE: PURIFICATION AND CHARACTERIZATION OF β‐CAROTENE‐RICH GLOBULES FROM DUNALIELLA BARDAWIL (CHLOROPHYCEAE)1
Authors: Ben‐Amotz Ami , Katz Adriana , Avron Mordhay 
Published: August 2007

ABSTRACT Dunaliella bardawil Ben‐Amotz & Avron, but not most other Dunaliella species, has a unique property of being able to accumulate, in addition to glycerol, large amounts of β‐carotene when cultivated under appropriate conditions. These include high light intensity, a high sodium chloride concentration, nitrate deficiency and extreme temperatures. Under conditions of maximal carotene accumulation D. bardawil contains at least 8% of its dry weight as β‐carotene while D. salina grown under similar conditions contains only about 0.3%. Electron micrographs of D. bardawil grown under conditions of high β‐carotene accumulation show many β‐carotene containing globules located in the interthylakoid spaces of the chloroplast. The same algae grown under conditions where β‐carotene does not accumulate, contain few to no β‐carotene globules. The β‐carotene‐rich globules were released from the algae into an aqueous medium by a two‐stage osmotic shock technique and further purified by centrifugal ion on 10% sucrose. The isolated purified globules were shown by electron microscopy to be free of significant contamination and composed of membrane‐free osmiophilic droplets with an average diameter of 150 nm. Reversed phase high performance liquid chromatography of a total pigment extract of the cells revealed the presence of β‐carotene as the major pigment, together with chlorophylls a and b, α‐carotene and the xanthophylls lutein, neoxauthin and zeaxanthin. β‐Carotene accounted for essentially all the pigment in the purified globules. Analysis of the algal and globule β‐carotene fractions by HPLC showed that the β‐carotene was composed of approximately equal amounts of all‐trans β‐carotene and of its 9‐cis isomer. Intact D. bardawil cells contained on a dry weight basis about 30% glycerol, 30% protein, 18% lipid, 11% carbohydrate, 9%β‐carotene and 1% chlorophyll. The β‐carotene globules were composed of practically only neutral lipids, more than half of which was β‐carotene. It is suggested that the β‐carotene globules may serve to protect D. bardawil against injury by the high intensity irradiation to which this alga is usually exposed in nature.
CONSPICUOUS ALGAL COLONIZATION OF THE ASH FROM MOUNT ST. HELENS1
Authors: Rayburn William R. , Mack Richard N. , Metting Blaine 
Published: August 2007

ABSTRACTConspicuous growth of green and yellow‐green algae developed in arid steppe communities in eastern Washington on the silt‐sized ash from the 18 May 1980 eruption of Mount St. Helens. In a veneer on the ash, cell numbers per gram dry ash of these aerial immigrants equaled or exceeded the highest reported values for terrestrial chlorophytes (108 cells · g−1 dry soil). Such pronounced growth was restricted largely to three microsites (under the canopy of Artemisia tridentata, along the runways of the vole, Microtus montanus, and surrounding emergent agarics), apparently in response to water‐holding properties of the ash, localized nutrient input and possible reduction of predation by nematodes. Highest algal counts were in Microtus runways where daily water and urea‐N input per adult animal may be 8 mL and 23 mg, respectively. Cyanophytes, commonly considered early colonizers of volcanic ash, were extremely rare. The role of blue‐green algae in succession on volcanic materials may be more restricted geographically than previously recognized.
ULTRASTRUCTURE OF SWARMERS IN THE LAMINARIALES (PHAEOPHYCEAE). I. ZOOSPORES1
Authors: Henry Eric C. , Cole Kathleen M. 
Published: August 2007

ABSTRACTZoospores of 17 species in 14 genera of Laminariales, collected in the northeast Pacific Ocean, were studied by electron microscopy. These zoospores are unique in the brown algae in lacking both an eyespot in the single chloroplast and any associated swelling at the base of the shorter, posterior flagellum. Spores of all species examined possess a distal whiplash portion on the longer, mastigoneme‐bearing anterior flagellum. This appendage may sometimes be as long as the mastigoneme‐bearing portion of the flagellum, but it is only seldom preserved in the preparations for electron microscopy. A microtubular cytoskeleton is probably responsible for maintaining the shape of the spore. It consists of a short band of about 10 microtubules between the two basal bodies, scattered tubules converging at the anterior of the spore, a band of 7–9 tubules directed anteriorly from the anterior basal body, and a band directed posteriorly from the posterior basal body. These anterior and posterior bands may form one continuous band looping around the periphery of the spore. Variation with possible taxonomic significance was found in the ultrastructure of vesicles which apparently contain adhesive material, and which are extruded through the plasmalemma when the zoospores settle.