bluuebunny/crossref_metadata_2025 huggingface dataset:
FLUORESCENCE INDUCTION AND PHOTOSYNTHETIC RESPONSES OF ARCTIC ICE ALGAE TO SAMPLE TREATMENT AND SALINITY1
Authors: Bates Stephen S. , Cota Glenn F.
Published: March 2008

The measurement of Photosynthetic rates of algae growing on the undersurface of 1. 7 m thick ice in the Canadian Arctic (Resolute Passage. N.W.T.) presents several problems. During the preparation of samples for physiological measurements, the ice algae may he exposed to salinity and temperature shocks. Fluorescence induction (the rise in in vivo Chl a fluorescence intensity during a period of millineconds) and photosynthesis‐irradiance (PI) experiments examined the potential effects of salinity and temperature on the physiology of ice algae.

Experimental suspensions were routinely prepared by scraping one part ire crystals (11–14%0 salinity) and attached algae from the bottom ice into four parts filtered seawater (32%0 salinity). giving a final salinity of 28–31%0. Post‐dilution of melted ice scrapings with seawater suppressed photosynthetic 14C‐fixation and decreased ADCMU (the area above the fluorescence induction curve measured in the presence of the inhibitor DCMC: an estimate of photosynthetic capacity) by a factor of 3–16. due to the low salinity of the melted ice scrapings. Fluorescence induction and PI experiments showed that the ice algae had a salinity optimum near 30%0, close to the ambient seawater salinity, Experiments in which the Chl a concentration was manipulated showed that ADCMU, Pam (Chl a‐normalized rate of photosynthesis at light saturation), and a (photosynthetic efficiency) declined with increasing Chl a concentration. Ice algae tolerated heating (l.5°C‐min‐1) up to 17° C, above which ADCMU’decreased with sample temperature.
CRYPTOENDOLITHIC ALGAL COMMUNITIES OF THE COLORADO PLATEAU1
Authors: Bell Robert A. , Athey Patrick V. , Sommerfeld Milton R.
Published: March 2008

Eighteen taxa, including representatives of both eukaryotic and prokaryotic genera, were isolated from below the surface of eight sandstones in four semi‐desert and cold temperate biomes of northern Arizona, southern Utah and Western New Mexico. The algae occurred as uniform well defined bands in light‐colored sandstones and also as scattered patches in dark sandstones. The algal communities varied in generic composition, chlorophyll a content, and location within the different sandstones. Biomass, estimated by chlorophyll a content, was approximately two to twenty‐fold greater than reported for cryptoendolithic algal bands in a cold desert habitat. The widespread distribution of certain algae in endolithic habitats of the Colorado Plateau and their presence in rocks at quite distant locations suggests that the endolithic habitat may he utilized by algae whenever it provides more favorable conditions than the surrounding surfaces.
THE UPTAKE OF MANNITOL AND SORBITOL BY A SPECIES OF CHLORELLA (CHLOROPHYCEAE)1
Authors: Colman Brian , Brickell Peter C. , Gehl Katharina A.
Published: March 2008

Chlorella saccharophila (Krüger) Nadson takes up mannitol and sorbitol in the light and the dark. The rate of uptake is concentration dependent. is not affected by pH in the range pH 6.0 to 8.0 and ii not stimulated by light. Uptake is inhibited by the respiration inhibitor sodium azide (10‐2 M) but not by 3‐(3,4‐dichlorophenyl)‐1,1‐di‐methyl urea (10‐6 M), an inhibitor of photosynthesis. Sorbitol. but not mannitol, stimulates the rate of dark respiration but both support the heterotrophic growth of the alga. Both compounds permeate the cells of C. miniata. and two strains of C. pyrenoidosa but do not support the heterotrophic growth of these algae. The cells of C. vulgaris are impermeable to both compounds.
PHYCOBILIPROTEIN COMPOSITION AND CHLOROPLAST STRUCTURE IN THE FRESHWATER RED ALGA COMPSOPOGON COERULEUS (RHODOPHYTA)1
Authors: Gantt Elisabeth , Scott Joe , Lipschultz Claudia
Published: March 2008

Serial sections of uncorticated axial cells of Compsopogon coeruleus revealed a single interconnected parietal chloroplast. Phycobilisomes in such chloroplasts were hemidiscoidal in shape with a broad‐face diameter of ca. 25–30 nm. The molar ratio of phycobiliproteins in whole cell extracts was IPE:3PC:1APC, similar to isolated phycobilisomes. Two spectrally distinct C‐phycocyanin forms (A618 nm, F648 nm and A630 nm, F652 nm) were resolved in dissociated phycobilisomes along with B‐phycoerythrin and allophycocyanin.
ULTRASTRUCTURE OF MEIOSIS INDASYA BAILLOUVIANA(RHODOPHYTA). I. PROPHASE I1
Authors: Broadwater Sharon , Scott Joe , Pobiner Bonnie
Published: March 2008

This first of two papers on ultrastructural observations of meiosis in the red algaDasya baillouviana (Gmelin) Montague describes stages of prophase I of meiosis. Although the five stages of prophase were originally derived from light microscopic studies, the same stages were utilized for this study based on the developmental sequence of the synaptonemal complex, which has the same morphology and mode of development as those reported for other red algae. The cytoplasm in early prophase sporocytes was typically less electron dense than either vegetative cells or sporocytes in later stages of meiosis. The reduction in density suggests clearing of ribosomes and other cytoplasmic components prior to conversion from sporophyte to gametophyte control. Leptotene cells often had an amorphous, chromatin‐free area, function unknown, which was not obviously associated with any specific nuclear region. Diplotene cells were characterized by nuclei containing prominent ring‐shaped nucleoli composed of a dark staining ring of material surrounding an electron‐translucent “vacuole.” Packets of electron‐dense, fibrillar material were often noted in the cytoplasm of late prophase cells. These packets are thought to he “nuage,” a term applied to large cytoplasmic aggregations of RNA in germ cells of several other phyla. It is suggested that nuage may represent a new infusion of ribosomal and messenger RNA for post‐meiotic development. The division pales are established by late prophase and a single polar ring is found within each large “exclusion zone” in close association with a pore‐free area of nuclear envelope. Both annulate lamellae and small, numerous vesicles are located in the exclusion zones. The significance of the various aspects of prophase I is discussed with the overall observation that this phase of meiosis in red algae is very similar to the process in higher plant and animal cells.
CELL FORM AND SURFACE PATTERNS INCHROOMONASandCRYPTOMONASCELLS (CRYPTOPHYTA) AS REVEALED BY SCANNING ELECTRON MICROSCOPY1
Authors: Kugrens Paul , Lee Robert E. , Andersen Robert A.
Published: March 2008

Fifteen freshwater cryptomonad species were freeze‐dried and examined with the scanning electron microscope. Surveys of cell surfaces revealed four general cell types. Chroomonastype cells lack a furrow but possess a shallow vestibular depression where the flagella are inserted. The presence of a gullet could not be detected. Cryptomonasspp. displayed three morphological types, all lacking gullets. The first type ofCryptomonashas a simple, shallow furrow with ridges that apparently can close to form a raphe but an oval opening or stoma remains at the posterior end and an opening from the vestibulum is formed at the anterior end. The secondCryptomonastype consists of a complex furrow with furrow ridges and folds that extend almost two‐thirds of the cell length. A sloma is present in the central region of the closed furrow. The folds apparently can separate thereby exposing the underlying furrow. The third type ofCryptomonaspossesses a simple, non‐closing furrow. At the anterior end there is a vestibular ligule which extends from the dorsalleft side of the cell and covers the region of the vestibulum where the contractile vacuole discharges.
LIPIDS IN BLUE‐GREEN ALGAL MATS (MODERN STROMATOLITES) FROM ANTARCTIC OASIS LAKES1
Authors: Orcutt David M. , Parker Bruce C. , Lusby William R.
Published: March 2008

Lipids comprising the stenols, stanols, polar lipid fatty acids, alkanes and alkenes of blue‐green algal‐(diatomaceous)‐microbial mats and cores (modern cold water stromatolites) collected from three Antarctic lakes were identified and compared with those of other algae. The major stenols were: (cholesta‐5, 22‐dien‐3β‐ol, cholest‐5‐en‐3β‐ol, 24‐methylcholesta‐5, 22‐dien‐3β‐ol, 24‐methyl‐cholest‐5‐en‐3β‐ol, 24‐ethylcholesta‐5, 22‐dien‐3β‐ol, and 24‐ethylcholest‐5‐en‐3β‐ol). The presence of C28 Δ3, 22 stenols, as well as other C28 stenols, was suggestive of diatom input. C29 stenols may have originated from blue‐grern algae. However, the high concentrations of stenols present and the lack of Δ7 stenols was atypical for known stenol components of several blue‐green algal species previously reported. The occurrence of these stenols and other lipid markers strongls implicate diatoms as well as blue‐green algae as important biogenetic sources of lipids and has established the potential for studies of lipid diagenesis in these unique cold, freshwater stromatolites.
ALGAL PHOTOSYNTHETIC MEMBRANE COMPLEXES AND THE PHOTOSYNTHESIS‐IRRADIANCE CURVE: A COMPARISON OF LIGHT‐ADAPTATION RESPONSES IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1
Authors: Neale Patrick J. , Melis Anastasios
Published: March 2008

Chlamydomonas reinhardtii was grown at photon flux densities (PFDs) ranging from 47 to 400 μE.m‐2 s‐1. The total cellular content of chlorophyll (Chl) was twice as high in the low light (LL) versus high light (HL) grown cells. On an equal Chl basis, photosystem II (PSII) and cytochrome f (Cyt f) content was higher in HL cells, but photosystem I (PSI) concentration displayed little variation with the light intensity during cell growth. Consequently, there was a shift in the ratio of PSII / PSI and Cyt / PSI from near unity in LL cells to greater than two in HL cells. The functional Chl antenna size of PSII and PSI ranged from 460 and 170 Chl (a + b)in HL‐grown cells to 620 and 370 Chl (a+ b)in LL‐grown cells, respectively. The initial slope of the Chl‐specific photosyn‐thesis‐irradiance (P‐I) curve was similar in LL‐ and HL‐grown cells, but the light saturated rate of photosynthesis was lower under LL. The response to low light was beneficial at the cellular level, since there was an enhancement of photosynthesis in LL. The PFD for the onset of light saturation, 1 was a factor of 2 lower in LL‐ relative to HL‐grown photosythetic membranes. Since growth PFD varied by a factor of ten, photosynthesis shifted from being light‐limited in the LL regime to light‐saturated in the HL regime. The requirement for balanced absorption of light by the two photosystems constrains the PSII / PSI ratio to near unity when growth is light‐limited, but such a constraint does not apply in HL conditions. Instead the concentration of individual electron transport complexes way be related to the pool size necessary for maximum rates of steady‐state electron transport. Thus the stoichiometry of electron transport complexes changes in response to growth PFD and this change is correlated with the response flexlbility of algal photosynthesis in diverse light environments.
THE HOST RANGE OF THE CHLORELLAVOROUS BACTERIUM (“VAMPIROVIBRIO CHLORELLVORUS”)
Authors: Coder David M. , Goff Lynda J.
Published: March 2008

The chlorellavorous bacterium. “Vampirovibrio chlorellavorus”Gromov et Mamkaeva, grows only by killing and consuming the cell contents of species of the green alga Chlorella Beijerinck. Of the 76 algal strains examined in this study, the bacterium attacks all 31 strains of the species C. vulgaris. C. sorokiniana, and C. kessleri, but attacks only two of 39 strains of nine other Chlorella species. Neither of two Prototheca strains was susceptible to attack. This narrow host specificity may be related to cell surface properties.
USE OF THE CRICKET ACHETA DOMESTICA L. AS A BIOASSAY ORGANISM FOR THE TOXIC EXTRACT FROM GONYAULAX MONILATA (DINOPHYCEAE)1
Authors: Bass Eugene L.
Published: March 2008

A toxic extract from unialgal cultures, of Gonyaulax monilata Howell was tested for insecticidal activity on the cricket Acheta domestica L The regression line of the activity was compared with that of ouabain in this insect as well as with that of the toxic extract in mice. Although mice are approximately 2.5°as sensitive as the cricket an a body weight basis, because of the insect's smaller mass‘(1/50 that of the mouse), one can treat 26° as many crickets with the same amount of toxic material. This fact, coupled with the simple rearing requirements of the insect, makes it an ideal bioassay organism as well as a useful subject far further investigations of the physiological properties of the toxic extract and other bioactive compounds available in limited quantities.
STRONG PROBABILITY OF LETHAL TOXICITY IN THE BLUE‐GREEN ALGA MICROCYSTIS VIRIDIS LEMMERMANN1
Authors: Watanabe Mariyo F. , Oishi Shihshi , Watanabe Yasunori , Watanabe Masayuki
Published: March 2008

Lethal toxicity (intraperitoneal, mouse) was examined in relation to Species composition of samples containing bloom‐forming Microcystis populations from natural waters and correlated with toxicity of laboratory strains of four Microcystis formas and species. Toxicity was not always associated with the presence of M. aeruginosa f. aeruginosa Elenkin. A sample with almost all cells of M. aeruginosa f. aeruginosa showed no toxicity, However samples comprised of a high percentage of M. viridis Lemmermann often showed lethal toxicity. Toxicity tests were done on culture strains M. aeruginosa f aeruginosa, M. aeruginosa f flos‐aquae Elenkin, M. viridis and M. wesenbergii Kamárek. All five cultured strains of M. viridis were found to be toxic, while only one out of nine strains of M. aeruginosa f. aeruginosa was toxic. Six strains of M. wesenbergii showed no toxicity, It is recommended that attention should be paid to the occurrences and possibility of toxic bloom of M. viridis from the standpoint of water management and public health.
ELECTRON MICROSCOPY OF MEMBRANOUS BODIES AND GENOPHORE IN CHLOROPLASTS OF BOTRYOCLADIA BOTRYOIDES (RHODYMENIALES, RHODOPHYTA)1
Authors: Tripodi Giacomo , Gargiulo Gaetano M. , Masi Flora de
Published: March 2008

An ultrastructural study on the chloroplasts of the red alga Botryocladia botryoides(Wulfen) J. Feldmann has been carried out to investigate the morphology of globular membranaous bodies (MBs) located between thylakoids. These membranous bodies show an electron dense lumen, in which a pair of denser cores occasionally occurs. The lumen is electron transparent in the chloroplasts of vacuolized, non‐dividing cells. The surface of MBs is in contact with the fibrils representing the plastidial genophore; the fibrils sometimes bridge the surface of MBs with the nearest thylakoid. In some planes of section a membranous stalk connecting a MB with thylakoids has been made evident.

Because the presence of similar bodies in chloroplasts and mitochondria of other red algae, as well as in mitochondria of yeast in which an intense synthesis of DNA occurs, the authors propose that MBs in red algae have a role in the replication of the genophore.
EFFECT OF TREE CANOPY REMOVAL BY GYPSY MOTH LARVAE ON THE MACROALGAE OF A RHODE ISLAND HEADWATER STREAM1
Authors: Sheath Robert G. , Burkholder JoAnn M. , Morison Mary O. , Steinman Alan D. , VanAlstyne Kathryn L.
Published: March 2008

A spring‐fed, headwater stream in central Rhode Island was examined during the period from June to October, 1979 to 1982. In the first two summers, a dense riparian canopy reduced the light penetration at the stream surface to a range of 5 to 18% of incident radiation. The lotic macroalgal community during this period was limited to 1 to 4 species covering < 1 to 35% of the stream bottom. However, in June and July, 1981, the surrounding leaf canopy was removed by a massive gypsy moth larval outbreak. Light penetration to the stream during this summer increased to 73% by early July, thereby resulting in a rise in water temperatures by 3.7°C. Even though there was a partial regrowth of leaves in late July and August of 1981, macroalgal cover values continued to rise to an early August peak of 80%. During the third summer, 88% of the macroalgal abundance could be attributed to illumination and water temperature. The filamentous diatom Funotia pectinalis (O.F. Müll.) Rabh. was the predominant species in the midsummer of all four years, accounting for at least 60% of the total cover. In 1981. an important taxon was the desmid Hyalotheca dissiliens (S. Smith) Bréb., a species which was not seen in other years. A less severe gypsy moth defoliation occurred in 1982 but did not produce significant differences in light, temperature or macroalgal cover from 1979 and 1980. The results indicate that light and temperature can be limiting during the summer in spring‐fed, headwater streams and that seed populations of some species are present in undetect‐able levels during these periods of suboptimal growth conditions. In addition, it appears that stream macroalgal communities can be quite resilient, recovering rapidly following a major perturbation.
REJUVENATION OF MELOSIRA GRANULATA (BACILLARIOPHYCEAE) RESTING CELLS FROM THE ANOXIC SEDIMENTS OF DOUGLAS LAKE, MICHIGAN, II. ELECTRON MICROSCOPY 1
Authors: Sicko‐Goad Linda
Published: March 2008

Detailed cytological changes that accompany the rejuvenation of resting cells of Melosira granulata were studied with the electron microscope. Dormant and viable cells that we previously classified as the condensed state generally contain definable chloroplasts, mitochondria, a nucleus and other cytoplasmic remnants. However, there appears to be a continuous cytoplasmic degradation spectrum and some cells which appear intensely colored with the light microscope have discontinuous chloroplast membranes and few other cytoplasmic remnants. Rejuvenation of viable dormant cells is initially accompanied by the accumulation of both lipids and polyphosphates. In the earliest stages of expansion, these storage products are dispersed throughout the cell. In later stages of expansion, the lipids appear to be coalesced into larger droplets which are easily identified at the light microscope level. The fully expanded stage is characterized by the normal complement of organelles and their arrangement at the periphery of the cells and central cytoplasmic bridge. These cells appear both anabolically and catabolically active as evidenced by the abundance of endoplasmic reticulum, ribosomes and secretory and lytic vesicles. Prior to cell division, both lipids and polyphosphates a re reduced or absent in the cells. The ultrastructural features of the dormant, condensed state in resting cells of M, granulata are similar to those described for hypnospores. A rejuvenation sequence that produces cytological features common to resting state formation could provide a population of cells which could easily revert should environmental conditions become adverse.
PHRAGMOPLASTS IN CYTOKINESIS OFCEPHALEUROS PARASITICUS(CHLOROPHYTA) VEGETATIVE GELLS1
Authors: Chapman Russell L. , Henk Margaret C.
Published: March 2008

Cytokinesis in apical cells of actively growing cultures ofCephaleuros parasiticusKarsten sporangiate thalli was examined with transmission electron microscopy. A massive, interzonal cytokinetic microtubule spindle is anchored at its poles to the medial surfaces of the daughter nuclei at telophase. Later, the daughter nuclei are widely separated and no longer associated with the interzonal spindle; however, the spindle retains its shape and becomes a distinct phragmoplast with an array of vesicles, presumably derived from dictyosomes, aligned in the division plane. Fusion of the vesicles gives rise to a thin cell plate. Some bundles of microtubules in the spindle appear to mark the sites of plasmodesmata formation, but no endoptasmic reticulum is directly involved in plasmodesmata formation. No infurrowing or phycoplast array of microtubules is involved in the cytokinesis. The relationship, if any. between the metaphase‐anaphase mitotic microtubule system and the interzonal cytokinetic spindle has not been determined. Cephaleuros parasiticus isone of only four green algae now known to contain a higher plant‐like phragmoplast and cytokinetic process. The observations reported can be interpreted as very strong evidence for a phylogenetic affinity between the Trentepohliaceae and the Charophyceae, but consideration of ulvophycean features of the Trentepohliaceae such as motile cell ultrastructure and life histories precludes unequivocal assignment of the family to either the Charophyceae or Ulvophyceae.
HYDROGEN ION BUFFERING OF CULTURE MEDIA FOR ALGAE FROM MODERATELY ACIDIC, OLIGOTROPHIC WATERS 1
Authors: Wehr John D. , Brown Lewis M. , Vanderelst Ingrid E.
Published: March 2008

Five hydrogen ion buffers were compared for their usefulness in regulating pH in a model oligotrophic, moderately acidic (pH 6.0) algal growth medium. These were 3,3‐dimethylglutaric acid (DMGA), tricarbaliylic acid (TCA), trans‐aconitic acid (tAA), N‐2‐hydroxyethylpiperazine‐N′‐2‐ethanesulfonic acid (HEPES) and 2‐(N‐morpholino) ethanesulfonic acid (MES). All buffers (2.5 mM) except HEPES limited the reduction of pH in a NH4+‐based medium during growth of Chrysochromulina breviturrita Nich. to less than 0.12 units, compared with more than 2 units in an unbuffered medium. Long term growth of C. breviturrita in these media was significantly inhibited (P < 0.05) by TCA and tAA. MES was able to control pH with the minimum amount of NaOH (1.0 mM) added to the medium to adjust to pH 6.0. Four of five bacterial isolates were capable of utilizing tAA as a sole organic‐C source, and no isolate could metabolize HEPES or MES. No significant differences (P > 0.05) were found in the maximum growth rates of six algal species (from five classes) in a medium with or without MES buffer, although significantly greater cell yields of Ochromonas danica Prings. were obtained in the buffered medium.

MES (pK4=6.15) was considered to be the most useful buffer in the pH range 5.0–6.5, due to its biological inertness, buffering capacity, the minimal requirement for excess base to adjust pH and its minimal metal complexing ability.
GROWTH RATE DEPENDENT OPTIMUM RATIOS IN SELENASTRUM MINUTUM (CHLOROPHYTA): IMPLICATIONS FOR COMPETITION, COEXISTENCE AND STABILITY IN PHYTOPLANKTON COMMUNITIES 12
Authors: Turpin David H.
Published: March 2008

Steady‐State growth equations predict that the optimum C:P ratio (R) of Selenastrum minutum (Naeq.) Collins should change by a factor of 20 over the growth range of this organism. Chemostat cultures were established at fixed inflow C:P ratios chosen such that a transition from carbon to phosphorus limitation should occur solely as a result of increasing the steady‐state growth rate. Measurements of residual dissolved inorganic carbon (DIC), cellular C:P, the kinetics of photosynthesis with respect to [DIC] and the response of culture biomass lo DIC or K2HPO4 additions were obtained. These results show that optimum ratios are growth rate dependent and that this dependency can be predicted based on steady‐stale algal growth equations.

A theoretical analysis was undertaken evaluating the range of growth rate dependent changes in the optimum ratio which could be expected for different nutrient pairs. Further analysis showed that, under certain conditions, the growth rate dependence of the optimum ratio may alter the breadth of zones of stable coexistence between species and allow for either the formation or complete elimination of such zones.
ALGAL COMMUNITIES OF SPRINGS AND STREAMS IN THE MT. ST. HELENS REGION, WASHINGTON, U.S.A. FOLLOWING THE MAY 1980 ERUPTION1
Authors: Rushforth Samuel R. , Squires Lorin E. , Cushing Colbert E.
Published: March 2008

Mt. St. Helens, a volcanic peak in the Cascade Range in southern Washington erupted violently on May 18, 1980, causing enormous damage to both terrestrial and aquatic ecosystems. The initial explosion evaporated, scoured or buried all springs and streams in the blast impact area. Ash fall and erosion from defoliated hillsides subsequently filled most of the lotic habitats with organic debris and volcanic ash. Recolonization of springs and streams by algae occurred quickly in areas where erosion through the ash progressed down to bedrock. Within 15 months or less of the eruption, algal communities were established throughout the blast impact area. However, as a result of the initial and continued disturbance these communities remained in an early successional stage. Floral assemblages were highly variable except that they were composed mostly of diatoms, with Achnanthes minutissima dominating most lotic sites. Springs showed the most rapid development toward stable floras.
THE GENUS HYPOGLOSSUM KÜTZING (DELESSERIACEAE, RHODOPHYTA) IN THE TROPICAL WESTERN ATLANTIC, INCLUDING H. ANOMALUM SP. NOV.1
Authors: Wynne Michael J. , Ballantine David L.
Published: March 2008

Observations are made on the occurrence and distribution of the red algal genus Hypoglossum Kützing (Delesseriaceae, Ceramiales) in the tropical western Atlantic. In addition to the type of the genus, H. hypoglossoides (Stackh.) Coll. & Herv., three other species are reported: H. anomalum sp. nov., H. involvens (Harv.) J. Ag., and H. tenuifolium (Harv.) J. Ag. A key is presented to distinguish these four species. The newly described species, H. anomalum, is like other species in the genus in that its branches arise endogenously from the primary axial row but it is unique in that the branches emerge from the parent blade at some point between the midline and the margin of the blade. The new species is reported from Puerto Rico and Florida.
HETEROTHALLIC SEXUALITY AND DENSITY DEPENDENT ENCYSTMENT IN THE CHRYSOPHYCEAN ALGA SYNURA PETERSENII KORSH.1
Authors: Sandgren Craig D. , Flanagin Joseph
Published: March 2008

Sexual reproduction of the common planktonic chrysophyte Synura petersenii is described from observations made on clonal isolates grown in defined culture. Sexual fusion was isogamous and heterothallic, with cells of normal appearance from compatible clones serving as hologametes. No special culture conditions were required to induce sexual behavior; actively growing cell populations appeared to be continually receptive to mating when mixed with a sufficient number of cells from a compatible clone. A single, bipolar mating group was documented containing five of the seven clones tested. Zygotic statospores were found to be binucleate and to contain 4 chloroplasts at maturity. Production rates of zygospores were low for even the most highly compatible clones, with batch culture yields ranging from 1‐20% of final cell density under the culture conditions utilized. Six of the clones tested were also capable of very low frequency (0.001‐0.01%) homothallic statospore production but the reproductive significance of these cysts remains enigmatic. The dynamics of sexual encystment suggest that the process proceeds during periods of active population growth and is density dependent. Based on the characteristics of cyst induction and encystment dynamics, it is concluded that chrysophycean flagellates may have a perennation strategy quite different from that of the majority of planktonic diatoms, dinoflagellates, and green algae for which resting cyst production requires an exogenous trigger usually associated with physiological stress and periods of negative growth.
THE INTRAMEMBRANOUS PARTICLE PROFILE OF THE PARAMYLON MEMBRANE DURING PARAMYLON SYNTHESIS IN EUGLENA (EUGLENOPHYCEAE)1
Authors: Kiss John Z. , Vasconcelos Aurea C. , Triemer Richard E.
Published: March 2008

Paramylon is the β‐1, 3‐glucan storage product in euglenoid algae. It is a fibrous crystal that occurs as membrane‐bound granules in the cytosol. The role of the surrounding membrane in paramylon synthesis was investigated by the use of freeze‐etch electron microscopy. When Euglena gracilis Klebs strain Z (Pringsheim) cells were frozen in supercooled liquid nitrogen, the fracture plane primarily was throuh the paramylon membrane. A large intramembranous particle (IMP, mean diam range 5.6‐6.5 nm) and a small IMP (mean diam range 9.6‐10.3 nm) were predominant in both PF (protoplasmic fracture) and EF (exoplasmic fracture) faces of the paramylon membrane. During paramylon synthesis induction, the ratio of small to large IMPs increased in both fracture faces. The IMP density decreased in both fracture faces concomitant to paramylon synthesis increase. These changes in IMP profile and density suggest that the paramylon membrane is involved in the synthesis of paramylon.
DAYLENGTH AND LIGHT RESPONSES IN GROWTH AND FERTILITY OF GLOSSOPHORA KUNTHII (PHAEOPHYTA, DICTYOTALES) FROM PACIFIC SOUTH AMERICA1
Authors: Hoffmann Alicia J.
Published: March 2008

Excised ligulae of Glossophora kunthii (C. Ag.) J. Ag. were cultured in photoperiods of 4–24 h and photon fluence rates of 10–75 μmol.m−2.s−1. Daylength interacted with irradiance on the growth of the ligulae. Maximal growth of primary ligulae occurred in long‐day regimens with high irradiances suggesting an effect of irradiance on photosynthesis and growth. In contrast, growth of secondary ligulae was greatest in short‐day regimes. Differences were significant at the highest irradiance tested. Differentiation of tetrasporangia on the ligulae is a short‐day photoperiodic response. Daylengths of 8.5 h or less induced a sharp increase in numbers of fertile ligulae and tetrasporangia attaining maturity. Interruptions of the dark period decreased the development of tetrasporangia; the number of interruptions had a cumulative inhibitory effect. Differentiation of reproductive structures was influenced by interactions of photoperiod and irradiance. Maximum numbers of tetrasporangia were formed at short‐day regimes and low irradiances; differentiation was completely inhibited at long‐day conditions and high irradiance.
LIGHT ACCLIMATION IN PORPHYRIDIUM PURPUREUM (RHODOPHYTA): GROWTH, PHOTOSYNTHESIS, AND PHYCOBILISOMES1
Authors: Levy Israel , Gantt Elisabeth
Published: March 2008

Acclimation to three photon flux densities (10, 35, 180 μE.m−2.s−1) was determined in laboratory cultures of Porphyridium purpureum Bory, Drew and Ross. Cultures grown at low, medium, and high PPFDs had compensation points of <3, 6, and 20 μE‐m−2.s−1, respectively, and saturating irradiances in the initial log phase of 90, 115, 175 μE.m−2.s−1 and up to 240 μE.m−2.s−1 in late log phase. High light cells had the smallest photosynthetic unit size (phycobiliproteins plus chlorophyll), the highest photosynthetic capacity, and the highest growth rates. Photosystem I reaction centers (P700) per cell remained proportional to chlorophyll at ca. 110 chl / P700. However, phycobiliprotein content decreased as did the phycobilisome number (ca. 50%) in high light cells, where as the phycobilisome size remained the same as in medium and low light cells. We concluded that acclimation of this red alga to varied PPFDs was manifested by the plasticity of the photosystem II antennae with little, if any, effect noted on photosystem I.
CHLORTETRACYCLINE‐INDUCED FORMATION OF WALL APPOSITIONS (CALLOSE PLUGS) IN INTERNODAL CELLS OF NITELLA FLEXILIS (CHARACEAE)1
Authors: Foissner Ilse
Published: March 2008

The formation of chlortetracycline (CTC)‐induced wall appositions or plugs in internodal cells of Nitella flexilis (L.) Ag. was studied with light, fluorescence and electron microscopy. These plugs contain callose and pectin. A few minutes after CTC addition plug formation starts by fusion of polysaccharide‐containing vesicles (glycosomes) with the plasmalemma. Plug growth is continued by incorporation of glycosome‐endoplasmic reticulum (ER) complexes. The cytoplasm near the plug appears dense because of the accumulation of glycosomes and the increased electron density of plasma matrix and organelles. About 1 h after CTC addition plug growth ceases, the cytoplasm recovers to its pretreatment appearance, and a few glycosomes fuse singly with the plug membrane. Crystalline inclusions which consist of hexagonally packed rods are found near the plug. Coated vesicles and coated pits are clearly seen only in very early and late stages of plug formation. Callose is also found in parts of wound plugs produced after mechanical injury. No callose is present in the underlying, highly ordered wound wall. The failure to produce a wound wall beneath CTC‐induced plugs appears to be related to the lower number of coated vesicles during plug formation. The possible significance of the partially coated reticulum in plug and wound wall formation is discussed.
SEASONAL PATTERNS OF MORPHOLOGICAL VARIABILITY IN SARGASSUM POLYCERATIUM (PHAEOPHYTA)1
Authors: Kilar John A. , Hanisak M. Dennis
Published: March 2008

Temporal variability in certain morphological and taxonomically important features was quantified for Sargassum polyceratium Mont. from a population in the Content Keys, Florida (U.S.A.). Patterns of blade development, senescence, and loss caused pronounced seasonal changes in blade length‐width ratios. Blade length and width were maximal early in the growing season (August‐November) and decreased as the annual stems matured. Early in the growing season, plants had broader blades with randomly distributed cryptostomata. Late in the growing season (February‐April), plants had more linear blades with cryptostomata approximately arranged in two rows, one on each side of the midrib. The length‐width ratio of blades increased acropetally along the stems and were directly correlated to the size of the cryptostomatal opening and inversely correlated with the number of cryptostomata. The branching pattern of the annual stems ranged from short spur branches to well‐developed, lateral axillary branches. The frequency of bifurcated blades increased significantly late in the growing season. Vesicle shape and size and pedicel length were temporally stable. Alated pedicels and mucronate vesicles occurred in low frequencies. The variability of the morphological features used to delineate species within the genus Sargassum on the tropical eastern coasts of the Americas is poorly understood.
STRUCTURE AND FUNCTION OF THE BRISTLES OF PEDIASTRUM BORYANUM (CHLOROPHYTA)1
Authors: Gawlik Stanley R. , Millington William F.
Published: March 2008

Tufts of long delicate bristles were detected on mature colonies of Pediastrum boryanum (Turp.) Meneghini. The bristles are not uniform in length and can exceed 100 μm. Bristle number per tuft can exceed eighty. Ultrastructure studies revealed that tufts are an aggregate of hexagonal tubules arranged in staggered rows. Each hexagonal tubule has an inner diameter of 6 nm and is made up of six interconnected subunits 4 nm in diameter that are shared by adjoining tubules. The bristles can be easily removed from mature colonies with a vortex stirrer. Removal of bristles from mature colonies in culture results in the loss of buoyancy and subsequent settling to the bottom of the flask.
THE FLAGELLAR APPARATUS AND RESERVOIR/CANAL CYTOSKELETON OF CRYPTOGLENA PIGRA (EUGLENOPHYCEAE)1
Authors: Owens Kristin J. , Farmer Mark A. , Triemer Richard E.
Published: March 2008

The flagellar apparatus and reservoir cytoskeleton of Cryptoglena pigra Ehrenberg are described. Three flagellar roots are associated with the two basal bodies. The four‐membered dorsal root arises from the dorsal basal body and extends anteriorly following the reservoir membrane. At the base of the reservoir the dorsal root nucleates a large microtubular group termed the dorsal band. The dorsal band continues anteriorlhy between the reservoir and eyespot and is continuous with the microtubules of the canal and ultimately the pellicle. The ventral basal body is associated with two roots. The four‐membered intermediate root proceeds anteriorly and extends the length of the reservoir. The seven‐to eight‐membered ventral root projects anteriorly along the reservoir membrane and bends away from the reservoir. At this point, the microtubules of the ventral root line a cytoplasmic pocket and are termed the MTR (reinforcing microtubules). The canal region is composed of longitudinal microtubules surrounded by two semicircles of microtubles. Ultimately, the fifteen ridges of the canal give rise to the pellicular ridges.
ENDOPHYTIC ALGAE OF CHONDRUS CRISPUS (RHODOHYTA). II. ACROCHAETE HETEROCLADA SP. NOV., A. OPERCULATA SP. NOV., AND PHAEOPHILA DENDROIDES (CHLOROPHYTA)1
Authors: Correa Jun A. , Nielsen Ruth , Grund Darryl W.
Published: March 2008

The occurrence of three endophytic green algae within Chondrus crispus Stackh. is reported. Two of them are new to science and are described as Acrochaete heteroclada Correa and Nielsen sp. nov. and A. operculata Correa and Nielsen sp. nov. The algae were studied in unialgal culture and in association with the host following infection of C. crispus under laboratory conditions. The experimental infection showed A. heteroclada to be initially epiphytic, with endophytic filaments growing into the cortex of the host during late infection. A. operculata is entirely endophytic when associated with the host. Phaeophila dendroides (Crouan frat.) Batters behaves as an epiphyte at 15 and 24°C but penetrates the host tissues at 20°C. For all three species, a close physical association with the host is established only when zoospores settle and germinate on the surface of C. crispus.
PHYCOGENETIC COMPARISON OF THE SMALL‐SUBUNIT RIBOSOMAL DNA SEQUENCE OF COSTARIA COSTATA (PHAEOPHYTA) WITH THOSE OF OTHER ALGAE, VASCULAR PLANTS AND OOMYCETES1
Authors: Bhattacharya Debashish , Druehl Louis D.
Published: March 2008

The small‐subunit ribosomal DNA (rDNA) coding sequence was determined for the help Costaris Costata (Phaeophyta) and compared to those of chlorophyll a + b‐ and chlorophyll a + c‐containing vascular and nonvascular plants. Phylogenetic comparison of all sequences indicated a common ancestor for phaeophytes, chrysophytes and oomycetes. Phylogenies based on rDNA sequence data and those based on plastid characteristics were compared. Relative evolutionary distances between some taxa, derived from rDNA sequence data, conflicted with findings of plastid‐based phylogenies.
THE MICROTUBULAR CYTOSKELETON OF AMPHIDINIUM RHYNCHOCEPHALUM (DINOPHYCEAE)1
Authors: Roberts Keith R. , Farmer Mark A. , Schneider Robin M. , Lemoine Julie E.
Published: March 2008

ABSTRACTS

The sub‐thecal microtubular cytoskeleton of Amphidinium rhynchocephalum Anissimowa was investigated using indirect immunofluorescence microscopy and transmission electron microscopy. The majority of sub‐thecal microtubules are longitudinally oriented and radiate from one of two sub‐thecal transverse microtubular bands that lie adjacent to the anterior and posterior edge of the cingulum.Both transverse bands consist of 3–5 microtubules and are loop shaped with one end adjacent to the cell's right edge of the sulcus and the other end adjacent to the fibrous ventral ridge. The posterior transverse microtubular band (PTB) defines the posterior edge of the cingulum and gives rise to numerous posteriorly directed longitudinal microtubular bundles that consist of 1–3 microtubules per bundle. These bundles end at the posterior end of the cell. The PTB also gives rise to the cingular longitudinal microtubules that underlie the cingular groove and terminate at the anterior transverse microtubular band (ATB). The ATB defines the anterior edge of the cingulum and loops around the base of the epicone. This band gives rise to anteriorly directed longitudinal microtubular bundles that terminate in the small epicone of the cell. The longitudinal microtubular root of the flagellar apparatus is directed posteriorly and lies immediately beneath the theca but is distinct from the subthecal microtubule system. A narrow fibrous ridge is ventrally located to the cell's left between the exit apertures of the transverse and longitudinal flagella. In this position, the ventral ridge lies between and also connects with the anterior and posterior transverse microtubular bands. The ventral ridge is also associated with three microtubules that are distinct from other cytoskeletal microtubules. Our results demonstrate that the majority of sub‐thecal microtubules originate from one of two microtubular bands associated with the cingulum. The possible role of the fibrous ventral ridge and its associated microtubules is also discussed.
PHYSIOLOGICAL ECOLOGY OF NITROGEN FIXING BLUE‐GREEN ALGAL CRUSTS IN THE UPPER‐SUBALPINE LIFE ZONE1
Authors: Fritz‐Sheridan Richard P.
Published: March 2008

Blue‐green algal (cyanobacterial) crusts composed of nitrogen fixing Nostoc commune Voucher ex Born. et Flah. and Tolypothrix conglutinata var. colorata Ghose were studied in the upper‐subalpine life zone, Mission Mountain Wilderness, Montana. Rates of ethylene production were highest in the submerged shoreline crusts, lower for exposed crusts pioneering rocky shorelines and lowest in the Carex meadow. Nitrogenase activity (acetylene reduction technique) was constant between 200–285% crust moisture content (wet/dry weight) and then rapidly declined to 0 between 200–140%. Optimal temperatures for ethylene production by illuminated cells was between 20–30° C for T. conglutinata, 20° C for N. commune and about 25° C in darkness for both species. Nitrogenase activity by T. conglutinata in culture was unaffected by repeated freeze‐thaw treatments whereas N. commune was severely inhibited. In contrast, N2‐ase activity of these two species in an intact crust was unaffected by repeated freeze‐thaw treatments. Application of nitrogen‐free growth medium to intact crusts increased nitrogenase activity by 3.7 times implying that these were mineral deficient under field conditions. Photosynthesis was light saturated at 125 μmol‐m−2.s−1 whereas nitrogenase activity was light independent for cells with carbohydrate reserves. When carbohydrate reserves were reduced by 8 h incubation in darkness, between 1–3 h of illumination were required to restore nitrogenase activity to 80% of the maximum rate. Biochemical pathway inhibitor studies employing DCMU, MFA, and CCCP showed that oxidative metabolism was the source of reductant for acetylene reduction. Tetrazolium precipitation in heterocysts paralleled acetylene reduction activity in the inhibitor treated cells.
DIEL PERIODICITY OF PHOTOSYNTHESIS AND CELL DIVISION COMPARED IN THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1
Authors: Putt Mary , Prézelin Barbara B.
Published: March 2008

Diel patterns of photosynthesis and cell division were examined in Thalassiosira weissflogii Grun. (clone Actin) grown in nitrogen‐limited cyclostat culture. Ammonia (NH4+) was either supplied continuously or as a daily pulse to cultures grown in constant light or in a light: dark cycle. When either nitrogen or light was supplied periodically, both cell division and photosynthetic capacity were periodic. When both nitrogen and light were supplied periodically, cell division was coupled to the N‐pulse whereas periodicities of photosynthetic capacity were modified but remained coupled to the light‐dark cycle. Diel oscillations in photosynthesis were i) largely independent of cellular pigmentation and ii) similar for light‐limiting and saturating irradiances. Periodicity in photosynthetic capacity also persisted following transfer of non‐dividing batch cultures to constant light. Results suggest that photosynthesis but not cell division was coupled to a circadian clock in T. weissflogii. A circadian rhythm of photosynthesis may optimize carbon assimilation in phytoplankton exposed to intermittent nutrient supply by ensuring that maximum photosynthetic capacity occurs during the day.
ASCOPHYLLUM NODOSUM (PHAEOPHYTA) IN AXENIC CULTURE AND ITS RESPONSE TO THE ENDOPHYTIC FUNGUS MYCOSPHAERELLA ASCOPHYLLI AND EPIPHYTIC BACTERIA1
Authors: Fries Lisbeth
Published: March 2008

Ascophyllum nodosum (L.) Le Jol. was freed from bacteria and the endophytic fungus Mycosphaerella ascophylli Cotton by repeated treatment with chlorine solutions and grown in artificial seawater. Two types of axenic culture of different origin were obtained. Type 1 was developed from apices of A. nodosum collected in the sea. Type 2 was from plants which developed from adventitious embryos on rhizoids formed by type 1. This is the first time A. nodosum has been cultivated axenically. Growth of the axenic alga was increased by IAA, 21P and zeatin. Without external growth regulators some strains of the axenic alga deteriorated within a year; others developed a filamentous habit. Sulfur in a reduced state also stimulated growth. Addition of either glucose, mannose or mannitol to the medium caused the formation of calluslike layers of loosely packed colorless cells under the epidermis of the thalli and the epidermis was sloughed off. No increase in thallus length was noticed.

Mycosphaerella ascophylli in axenic culture did not excude any substances stimulating growth of the alga, but that does not exclude an influence of the fungus on the alga in vivo. The fungus, when growing within the alga, seemed to have little influence on algal morphology. A bacterized but fungus‐free A. nodosum was cultivated in an artificial seawater for 8 years. In the bacteria‐free alga, the fungus protruded from the epidermis and evidently utilized the alga as a carbon source. The bacteria thus seem much more important than the fungus for normal growth of the Ascophyllum plant.
INTERACTIONS BETWEEN PULSED NUTRIENT SUPPLIES AND A PHOTOCYCLE AFFECT PHYTOPLANKTON COMPETITION FOR LIMITING NUTRIENTS IN LONG‐TERM CULTURE1
Authors: Brzezinski Mark A. , Nelson David M.
Published: March 2008

The influence of periodic nutrient supplies and a photocycle on phytoplankton competition for limiting nutrients was examined using the diatoms Thalassiosira rotula Meunier (clone 411) and Chaetoceros sp. cf. vixvisibilis Schiller (clone 847). Chaetoceros sp. cf. vixvisibilis displaced T. rotula from ammonium‐limited cultures under constant light irrespective of whether ammonium was supplied continuously, in 6 pulses.day−1 or in a single daily pulse. In contrast, the species coexisted under the 14:10 h LD photocycle under either continuous or pulsed ammonium supplies with the relative abundance of C. sp. cf. vixvisibilis increasing as the interval between ammonium additions lengthened. Coexistence was not observed with either silicic acid or nitrate limitation. Chaetoceros sp. cf. vixvisibilis displaced T. rotula from both nitrate‐ and silicic acid‐limited chemostat cultures and from semi‐continuous cultures grown under the same photoperiod that produced coexistence with a daily pulse of ammonium.

The presence of a photocycle was both necessary and sufficient to permit coexistence with ammonium limitation. Under continuous ammonium supply the photocycle may have induced a temporal separation of ammonium uptake between species, permitting sharing of the limiting nutrient and coexistence. In contrast, the species were shown to be in direct competition for the daily ammonium pulse. A competition model suggested that coexistence in this case arose from a balance between the species’ammonium uptake rates and their nitrogen demands for steady‐state growth induced by the photocycle. The results indicate that variations in nutrient supply rates may contribute to the coexistence of phytoplankton species in the sea, but that the identity of the limiting nutrient and the influence of variations in other non‐limiting resources play important roles in affecting the outcome of nutrient competition among planktonic algae.