Showing papers in "Journal of Phycology in 1977"

Effect of blue‐green light on photosynthetic pigments and chloroplast structure in unicellular marine algae from six classes1

Abstract: The photosynthetic pigments of 17 species of unicellular marine algae grown in white and blue-green light were examined. Blue-green light (400 μW·cm−2; 12:12 LD cycle) caused major chlorophyll increases (55–146%) in five diatoms, one dinoflagellate and one cryptomonad; minor chlorophyll increases (17–39%) in two diatoms, two dinoflagellates, one prymnesiophyte (haptophyte), one chrysophyte and one chlorophyte; and no chlorophyll increase in two diatoms and one pyrmnesiophyte (haptophyte). The relative proportions of major chlorophylls and carotenoids did not change, but in six of eight species tested small increases in the concentration of chlorophyll c occurred. Blue-green light caused a small increase in the concentration of phycoerythrin relative to chlorophyll a in the cryptomonad. A larger number of thylakoids per chloroplast were observed in six species grown in blue-green light compared to white light controls. The ultrastructure changes observed depended not only on the magnitude of the chlorophyll increase but also on the architecture of the chloroplast.

Alcian blue: a quantitative aqueous assay for algal acid and sulfated polysaccharides1

Abstract: Alcian 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.

Calcification in the green alga halimeda. i. an ultrastructure study of thallus development1

Abstract: The ultrastructure of 4 species of the calcareous, siphonaceous alga Halimeda (H. cylindracea Decaisne, H. discoidea Decaisne, H. macroloba Decaisne and H. tuna (Ellis & Solander) Lamour) has been studied, and the observed changes during growth and development are related to changes in the degree of calcification. A distinct gradient in the types and quantities of cell organelles exists in a growing apical filament. As these filaments grow, branch, and eventually develop into a mature segment, changes in the organization of organelles such as mitochondria and chloroplasts are observed. Calcification begins when the chloroplasts reach structural maturity and when the peripheral utricles adhere (fuse). This adhesion of the peripheral utricles isolates the intercellular space (ICS) in which calcification occurs from the external seawater. Calcification begins in the outermost (pilose) cell wall layer of the walls facing into the ICS. The cell walls at the thallus exterior undergo extensive changes after utricular fusion; the pilose layer is lost, the cuticles of adjacent utricles fuse forming a ridge at their junction, and multiple cuticles are formed. The aragonite (CaCO3) crystals which are initially precipitated within the pilose wall layer, rapidly increase in size and number, eventually filling much of the ICS. Only the initial nucleation of aragonite is associated with the pilose wall layer, the later precipitation of aragonite is totally independent of the pilose layer. In older segments secondary deposition of CaCO3 also occurs around existing aragonite needles.

Sexual reproduction of peridinium gatunense (dinophyceae)1

Abstract: Sexual reproduction was induced in the dinoflagellate Peridinium gatunense Nygaard when exponentially growing cells were inoculated into nitrogen deficient medium. Small thecate cells produced by division of vegetative cells then acted as gametes. Thecae of fusing gametes broke in the girdle region and were lost. Zygotes thus formed remained motile 3–5 days during which time they enlarged slightly with the newly formed theca becoming warty. Three to 5 days following plasmogamy the zygote became nonmotile, the protoplast contracted, and the cell wall thickened. Hypnozygotes with 4 nuclei were observed ca. 10–12 h following formation. Meiosis was inferred. Hypnozygotes germinated within 12 h of formation producing 2 vegetative cells which divided within a 24 h period. Attempts to induce sexual reproduction by inoculation of cells into media deficient in a number of basic elements other than N were unsuccessful.

Steady state growth of phytoplankton in continuous culture: comparison of internal and external nutrient equations1,2

Abstract: Previously, there have been conflicts over whether external or internal nutrient concentrations control phytoplankton growth rates at steady state in continuous culture. To experimentally demonstrate that both equations equally describe steady state growth, continuous culture studies with phosphorus-limited growth of the chrysophyte Monochrysis lutheri Droop were carried out over the entire growth rate region up to biomass washout. Data were examined using both the Monod and Droop equations, and, even though there were significant variations in the yield coefficient with growth rate, the data fit both equations reasonably well. Because of their relative simplicity, the Droop equation and an equation combining both the Monod and Droop equations are better suited for expressing kinetic data than the Monod equation. It is crucial, though, that the criteria necessary to achieve steady state be fulfilled.

Effects of light intensity and temperature on cryptomonas ovata (cryptophyceae) growth and nutrient uptake rates1

Abstract: Specific growth rate of Cryptomonas ovata var. palustris Pringsheim was measured in batch culture at 14 light-temperature combinations. Both the maximum growth rate (μm) and optimum light intensity (Iopt) fit an empirical function that increases exponentially with temperature up to an optimum (Topt), then declines rapidly as temperature exceeds Topt. Incorporation of these functions into Steele's growth equation gives a good estimate of specific growth rate over a wide range of temperature and light intensity. Rates of phosphate, ammonium and nitrate uptake were measured separately at 16 combinations of irradiance and temperature and following a spike addition of all starved cells initially took up nutrient at a rapid rate. This transitory surge was followed by a period of steady, substrate-saturated uptake that persisted until external nutrient concentration fell. Substrate-saturated NO3−-uptake proceeded at very slow rates in the dark and was stimulated by both increased temperature and irradiance; NH4+-uptake apparently proceeded at a basal rate at 8 and l4 C and was also stimulated by increased temperature and irradiance. Rates of NH4−-uptake were much higher than NO3−-uptake at all light-temperature combinations. Below 20 C, PO4−3-uptake was more rapid in dark than in light, but was light enhanced at 26 C.

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

Abstract: The 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.

Effect of blue-green light on photosynthetic pigments and chloroplast structure in the marine diatom stephanopyxis turris1

Abstract: Blue-green light increased the chlorophyll concentration and chloroplast number of cells of Stephanopyxis turris (Grev.) Ralfs, compared to white light controls. Light fields for growth were 400 μW·cm−2 (12:12 LD cycles). Chlorophyll increased up to 100%/cell, but no change in the ratio of chlorophylls to major carotenoids occurred. The effect was, therefore, not that of complementary chromatic adaptation. At the same time, blue-green light enhanced the photosynthetic fixation of CO2. At the ultrastructure level, an increase in, and rearrangement of, the thylakoid system occurred.

Antiviral substances from california marine algae1

Abstract: Extracts of 28 species of marine macroscopic algae collected from various coastal habitats of northern California were examined for antiviral activity against a broad spectrum of mammalian viruses. Ten members of Rhodophyta contained substance(s) which caused greater than a 2 log reduction in the infectivity of herpes simplex virus types 1 and 2. In addition, anti-Coxsackie Bs virus activity was detected in extracts of Constantinea simplex Setchell. The physical and chemical properties of the substance in extracts of Farlowia mollis (Harvey and Bailey) Farlow and Setchell and C. simplex indicated the active agent was a structural polysaccharide.

DIATOM MINERALIZATION OF SILICIC ACID. II. REGULATION OF Si (OH)4 TRANSPORT RATES DURING THE CELL CYCLE OF NAVICULA PELLICULOSA1

Abstract: Synchronized populations of Navicula pelliculosa (Breb.) Hilse show a 10-fold increase in Si(OH)4 transport rate during traverse through the cell division cycle. The transport activity pattern is similar to a “peak enzyme.” Kinetic analysis showed there was a significant change in Ks values, indicating increased “affinity” for Si(OH)4 as cells neared maximal uptake rates. However, the dramatic changes in transport rate at various cell cycle stages were also reflected by alterations in the Vmax, values of the transport process, suggesting a change in the number of functional transport “sites” in the plasma membrane. Cells in the wall forming stage, arrested from further development by Si(OH)4 deprivation, maintained high transport rates for as long as 7 h. The rates decreased rapidly if protein synthesis were blocked or if Si(OH)4 was added, the latter allowing the cells to traverse the rest of the cycle. The half-life of the transport activity ranged from 1.0 to 2.2 h when protein synthesis was inhibited at various cell cycle stages and during the natural decline of activity late in the cycle. The transport system appears to be metabolically unstable as is typical for a “peak protein.” The rise in transport rate through the cell cycle did not depend on the presence of Si(OH)4 in the medium; therefore, the transport system does not appear to be induced by its substrate. The rise in transport is also observed in L:D synchronized cells developing in the presence of Si(OH)4; neither does the transport system appear to be derepressed. The transport rate was strongly cell cycle-stage dependent; the data appeared to fit the “dependent pathway” model proposed by Hart-well to explain oscillations in enzyme synthesis during the cell cycle.

Culture and hybridization studies on gigartina papillata (rhodophyta)1

Abstract: The foliose red alga Gigartina papillata (C. Ag.) J. Ag. was studied in culture to determine its life history and possible relationship to the life history of Petrocelis middendorffii (Ruprecht) Kjellman. Carpospores cultured from individual female plants gave rise to either crustose Petrocelis-like plants that reproduced by tetraspores, or to another generation of foliose female (cystocarpic) plants that reproduced by carpospores. Apices cultured from blades of individual field-collected female plants produced either papillae with many procarps that developed cystocarps only when crossed with male plants, or papillae with few procarps that produced cystocarps in the absence of male plants. The results are interpreted to demonstrate that two types of life history occur in G. papillata: one, a sexual life history involving a crustose tetrasporophyte; the other, a possibly apomictic life history involving only cystocarpic plants. Hybridization experiments demonstrated, that G. papillata is interfertile with Gigartina-phase gametophytes cultured from tetraspores of P. middendorffii. Sexual plants of G. papillata are postulated to represent the naturally-occurring gametophyte of P. middendorffii in California. The possible relationships of the sexual and apomictic plants of G. papillata are discussed.

Structural, chemical and ecological studies on iridescence in iridaea (rhodophyta)1

Abstract: Transmission electron microscopy of the iridescent algae Iridaea flaccida (S & G) Silva, Iridaea cordata (Turn.) Bory var. cordata and I. cordata var. splendens (S & G) Abbott reveals a multilaminated cuticle covering the thallus. Experimental results show the cuticle: a) can be isolated intact by mechanical scraping or NaOH treatment; b) is iridescent by itself and the denuded thallus is not; and, c) is isolated without any subtending polysaccharide layer, cell walls, or cells. This cuticle acts as a thin layer producing the constructive and destructive light interference which is seen as iridescence. It is formed of alternating electron opaque and translucent layers with a total thickness of 0.5–1.6 μm. Analysis of mechanically isolated cuticle shows that it is composed of protein (50%), carbohydrate (ca. 40%), inorganic salts (5%) and some fatty acids (less than 1.0%). The electron opaque layers may correspond to protein-rich regions and the electron translucent ones to regions rich in carbohydrates. The cuticle does not appear to affect photosynthesis or respiration, but rather, may protect the alga from physical factors such as desiccation and from predator injury. It is likely that the iridescence in other foliaceous red algae is caused by a similar structure.

An aberrant chrysophycean alga pelagococcus subviridis gen. nov. et sp. nov. from the north pacific ocean1,2

Abstract: A description and Latin diagnosis of the new genus and species Pelagococcus subviridis Norris is presented. Pale green, spherical cells appeared in enrichment cultures initiated from water samples collected at stations between 132°W and 175°W and between 45°N and 50°N in the North Pacific Ocean. The alga is placed in the Chrysophyceae based on organelle fine structure, and presence of chlorophylls a and c, diatoxanthin, diadinoxanthin and two fucoxanthin-like pigments. There are a number of atypical features however; the two fucoxanthin-like pigments differ from true fucoxanthin; there is only chlorophyll c2 (not C1+ c2); probably mostly a, not β-carotene; half of the chlorophyll a is in the form of chlorophyllide a.

Ecology and natural history of iridaea cordata (gigartinales, rhodophyta) growth1

Abstract: The in situ growth, maturation and senescence, of central California Iridaea cordata (Turner) Bory was studied. This ontogenetic progression was quantified by measuring development and growth of: i) individually tagged blades, and ii) populations of blades within cumulative (1-yr duration) and seasonal experimental plots. Greatest growth and longest life span were exhibited by winter-spring initiated blades, and were correlated with a rapid increase, in irradiance, but not with either seawater temperature or nutrients. Tagging studies showed that reproductive maturation and senescence of blades occurred throughout the year, irrespective of date tagged, growth rate or size. Moreover, the majority of blades continued to elongate following maturation, and some matured within 3 mo of initiation at all seasons but winter. At the population level maturation took place primarily during summer-autumn when 90 ±2% of the population was mature. The majority of the population senesces or “dies back” during autumn-winter. It is concluded that in situ, the blades are derived almost totally via vegetative means involving perennation. This indirectly suggests that sexual reproduction or the success of sporeling development are marginal. Additionally, the species is perennial with annually deciduous blades, characterized by both rapid growth and maturation.

Comparison of attached diatom communities on natural and artificial substrates1

Abstract: A study of attached diatom communities on artificial and natural substrates was conducted in Wheelwright Pond, New Hampshire, during 1975. There were differences in the species composition growing on artificial glass slides and natural substrates. The slides favored the accumulation of Achnanthes minutissima Kutz. and decreased the relative abundance of Eunotia incisa W. Sm. ex. Greg. and Cocconeis placentula v. euglypta (Ehr.) Cleve. Large growths of planktonic species were also noted on the slides. Compositional differences between slides positioned at 15–30 cm (upper) and 1 m (lower) from the surface of the water were minimal. A similar community composition of periphytic diatoms was found on five aquatic macrophytes.

Factors influencing the toxicity and animal susceptibility of anabaena flos‐aquae (cyanophyta) blooms1

Abstract: Biological factors have been found which can catise variable toxicily of colony and clonal isolates of Anabaena flos-aquae (Lyngb.) de Breb. when cultured in the laboratory. These factors help to explain some of the variable toxicity of and animal .susceptibility to A, ilos-aquae blooms in nature. Two bacteria in the Enterobacteriaceae isolated from a toxic waterbloom, depressed toxin production in selected bacteria-free toxic clones of A. flosaquae. These toxin-depressing bacteria decreased culture toxicity 3-fold from 80 to 240 mg/kg (intraperitoneal in male mice). Many colony isolates from, a toxic bloom had minimum lethal dosages (LD^i,^) greater than 240 mg/kg. This was because they were composed of mixtures of toxic and nontoxic filaments. The oral LD^^^„ of the toxin from A. flosaqtiae clonal isolate NRC-44-1 varied significantly for 6 different animal species. Using these oral LD,,,fn it is estimated that a surface-concentrated bloom of toxic A, flos-aquae, having a biomass density of 20 mg/rnl dry lueight, would cause death of ducks or calves when 20 ml/kg was consumed whereas a monogastric animal such as a rat would require 80 ml/kg.

Distribution of diatoms in the plankton of yaquina estuary, oregon1

Abstract: The distributional patterns of diatoms in the plankton of the Yaqnina Estuary, Oregon, were, investigated and related to selected climatic and hydrographic factors. Distribution was strongly influenced by seasonal patterns of rainfall resulting in the introduction of a large volume of fresh water into the estuary during fall and winter. Plankton assemblages in spring, summer and fall had fewer diatom species and exhibited a more rapid rate of change in species composition than in winter. Winter assemblages were further characterized by many pennate diatoms, apparently dislodged from the benthos during periods of high freshwater discharge and silt loads. A statistical measure of community difference indicated an increase in taxonomic homogeneity among assemblages throughout the estuary with the onset of the rainy season in late fall and a gradual transition to a more heterogeneous system again during late spring. Canonical correlation ordered 20 prominent diatom taxa along the salinity gradient and identified possible relationships among certain taxa and selected environmental variables, namely visible light energy and temperature. Redundancy in the species data given the environmental data was only 40%, emphasizing the difficulty in demonstrating a quantitive relationship between plankton dynamics in the field and concurrent measurements of chemical and physical variables.

Effects of iron deficiency on isochrysis galbana (chrysophyceae) and phaeodactylum tricornutum (bacillariophyceae)1

Abstract: Cultures of Isochrysis galbana Parks and Phaeodactylum tricornutum Bohlin were grown in iron-limited chemostats. With increasing iron deficiency, photosynthetic rate per cell and assimilation number decreased. The pattern of photosynthesis was also altered; in Fe deficient cells the proportion of 14C fixed in glycine and serine decreased with an accompanying increase into alanine after 3 min assimilation. Although there was no significant effect of Fe deficiency on the proportion of 14C incorporated into total amino acids and amides, the percentage of total 14C fixed in protein increased with increasing Fe deficiency. Cellular levels of chlorophyll a, carotenoids, cytochromes and protein also decreased with increasing Fe deficiency. However, the reduction in chlorophyll a/cell was not as great as that of cytochrorne f1 and Fe deficient cells therefore showed a marked increase in chlorophyll a:cytochrorne f1 ratio.

Photosynthesis in the snow: the alga chlamydomonas nivalis (chlorophyceae)1

Abstract: Red blooms of snow algae consisting almost exclusively of large spherical red cells of Chlamydomonas nivalis (Bauer) Wille are widespread during the summer in the Beartooth Mountains in Montana and Wyoming. Field studies designed to examine the effects of temperature, light, and water potential on algal activity were performed with natural populations using photosynthetic /sup 14/C-HCO/sub 3//sup -/ or /sup 14/CO/sub 2/ incorporation as a measure of activity. The algae photosynthesized optimally at 5.4 x 10/sup 4/ lx, but were not inhibited by increased light intensity up to 8.6 x 10/sup 4/ lx, the maximum observed in the field. Photosynthesis was sensitive to a reduction in water potential, and since low water potentials develop in snow at temperatures below 0 C, it is unlikely that significant algal activity occurs at the sub-0 temperatures which occur throughout winter. Photosynthesis was much lower following melting of the snow, but this was probably due to decreased diffusion of CO/sub 2/. The optimal temperatures varied considerably among the different algal populations. Most samples photosynthesized optimally at 10 or 20/sup 0/C but retained substantial activity at temperatures as low as 0 or -3/sup 0/C. Exceptional samples photosynthesized optimally at 0 or -3/sup 0/C. It ismore » proposed that the varied temperature responses reflect the presence of different temperature strains. Taken together, the data suggest that development of the snow algae can occur only during the summer months.« less

Pigments of the dinoflagellate peridinium balticum and its photosynthetic endosymbiont1

Abstract: An 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).

Polymorphic behavior of ulva lactuca (chlorophyta) in axenic culture. i. occurrence of enteromorpha‐like plants in haploid clones1

Abstract: An isolate of Ulva lactuca L. was brought into axenic culture in both defined synthetic medium and enriched seawater. Haploid clones were established and followed through several generations in both media. Plants possessing distromatic, partially distromatic or completely tubular blades in cross sections, as well as individuals that were completely distromatic in one area of the blade and tubular in another all developed from the same swarmer population. Variations in basal area morphology also occurred. Progeny from swarmers of any of these morphological types showed a similar mixture of morphological variation, indicating non-mutational variability in phenotypic expression of the blade and basal areas. A mechanism by which such variation may occur without mutation is discussed.

Nitrate uptake kinetics and clonal variability in the neritic diatom biddulphia aurita1

Abstract: Nitrate uptake experiments were conducted at 18 and 25 C on subtropical and temperate isolates of the neritic diatom Biddulphia aurita (Lyngb.) Breb. & Godey. Two clones (STX-88 and B1) were grown in a 12:12 LD cycle in NO3-limited continuous cultures used for uptake experiments. The half-saturation constant (Ks) and the maximum NO3- uptake rate (Vm) were measured under conditions in which external NO3- concentration controlled uptake rate. The kinetic constants for both clones were higher at the higher temperature. The subtropical clone (STX-88) had lower kinetic values than temperate clone (B1) at both temperatures. The differences appear to be of adaptive significance since STX-88 has a NO3- uptake system, described by its lower Ks value, which minimizes the double stress effects of high temperature-low NO3- concentration conditions characteristic of its habitat. Cytoplasmic enzyme electrophoretic analyses were conducted on the clones. Differences in banding patterns and mobilities showed evidence of allelic substitution. The results suggest genetic variation at the intraspecific level.

Ultrastructure of cyst formation in ochromonas tuberculata (chrysophyceae)1

Abstract: The 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.

Comparisons of salt‐marsh fucoid production estimated from three different indices1

Abstract: Production 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/m/sup 2/ 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/sup -2/ . yr/sup -1/. On the other hand, production of both fucoids calculated from standing-crop data was only 155 g c . m/sup -2/ . yr/sup -1/.

Ultrastructure of a chain-forming diatom phaeodactylum tricornutum1

Abstract: The ultrastructure of a chain-forming clone of the polymorphic diatom Phaeodactylum tricornutum Bohlin has been studied by scanning and transmission electron microscopy. Both fusiform and tri-radiate cells are capable of forming chains. The cells, lacking any silica shell, are attached to each other at the central region of the theca, leaving the arms free. Neither homogenization nor sonication completely disrupts the chains. The attachment is due to fusion of the cell wall in the central region of the cell during cell wall deposition. This fusion results from failure of the cytoplasmic cleavage furrow to separate the plasma membranes of the two daughter cells sufficiently so that a single wall is deposited instead of two separate walls. Possible explanations for this are discussed.

Probing phycobilisome structure by immuno‐electron microscopy1

Abstract: By immuno-electron microscopy it was shown that phycoerythrin is located on the outer surface of the phycobilisome and allophycocyanin is on the inside near the photosynthetic membrane in the red alga Porphyridium purpureum (Bory) Drew & Ross (P. cruentum). These findings are consistent with the idea that the phycobilisome junctions as a light harvesting antenna and energy sink, which directs the energy to chlorophyll in the photosynthetic membrane. A technique was devised in which unfixed phycobilisomes, attached to thylakoid vesicles, were separately reacted with three monospecific antisera (to B-phycoerythrin, R-phycocyanin and allophycocyanin) and the reaction products were secondarily marked by reaction with ferritin-conjugated goat-antirabbit gamma globulin fraction. This was subsequently followed by glutaraldehyde fixation and staining with phosphotungstic acid. The entire procedure was carried out on an electron microscope grid. The results confirm the previously proposed phycobilisome structural model.

Accumulation of water soluble phosphorus and hydrolysis of polyphosphates by cladophora glomerata (chlorophyceae)1,2

Abstract: Concentrations of hot-water extractable phosphorus from most samples of Cladophora glomerata (L.) Kutz. were relatively high (0.06–0.68%) and correlated closely with total dissolved P in ambient Lake Michigan water. Cladophora was able to hydrolyze polyphosphates by enzymes found in intracellular, extracellular and cell wall fractions. The intracellular phosphatase activity is pH dependent with the optimal hydrolysis rate at pH 7.8. Secretion of phosphatases is affected by pH, with maximum rate at 7, but affected little by light intensity. Magnesium is the most effective metallic cofactor required for maximal rates of intracellular phosphatase activities.

Maturation of algal zygotes: alternative experimental approaches for chlamydomonas reinhardtii (chlorophyceae)1

Abstract: Young 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.

An investigation of the vertical distribution of selected benthic marine algae with a tide–simulating apparatus1

Abstract: The growth yields of 8 species of red and 4 species of green algae, collected from various vertical levels on the western Atlantic (New Jersey) shore, were investigated in a range of emersion-submersion regimes in the laboratory. The sinusoidal tide-simulating apparatus consisted of a plexiglass frame connected by a nylon thread to a rotating wheel, powered by an electric motor geared to make one revolution every 12 h. Inocula of settled spores on glass cover-glasses were placed at 6 levels on the frame and alternately raised out of, and lowered into, a seawater tank every 6 h with consequent subjection to 0, 18, 37, 58, 79, and 100% submergence regimes per tidal cycle. There was little correlation between the vertical position of a species on the shore in nature and its ability to grow as the percentage submergence per tidal cycle increased. All species tested grew best when continuously submerged, even those that are usually restricted to elevated positions on the shore in nature. The majority grew well in all regimes in which there was some submergence per tidal cycle, except for one sublittoral species (Callithamnion byssoides) whose growth decreased sharply as the percentage exposure to the air was increased.

Copper sorption and release by cyclotella meneghiniana (bacillariophyceae) and chlamydomonas reinhardtii (chlorophyceae)1

Abstract: Initial Cu++ sorption by Cyclotella meneghiniana Kutz. (Cu++-sensitive) and Chlamydomonas reinhardtii Dangeard (Cu++-resistant) was rapid in the first 5 min of Cu++ incubation with little sorption after 2 h. On a cell to cell basis, Cyclotella sorbed ca. five times more Cu++ from the medium than Chlamydomonas. In MBL medium with EDTA Cyclotella and Chlamydomonas cells sorbed 21.0 and 4.41 nM Cu++/106 cells respectively in 6 h with 0.3 mg Cu++/l in the medium. Proportionally similar quantities of Cu++ were sorbed when the cells were Cu++ incubated in MBL + citrate or filtered lake water. Cleaned cell walls of Cyclotella sorbed little Cu++ (1.7 nM/106 cells) as compared to living cells (17.5 nM Cu++/106 cells) in 3 h. Therefore, in living Cyclotella most of the Cu++ taken up must be absorbed by the protoplasm or perhaps by the organic layer surrounding the silica wall. Cleaned cell walls of Chlamydomonas sorbed 3.5 nM Cu++/106 cells and living Chlamydomonas cells sorbed 2.6 nM Cu++/106 cells. This indicates that most of the Cu++ sorbed by Chlamydomonas cells remained bound to the cell wall and probably did not readily enter into the protoplasm: When placed in Cu++ free medium after Cu++ incubation, Cyclotella and Chlamydomonas cells released 46 and 59% respectively of the Cu++ sorbed.