bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

ABSTRACTChlamydomonas 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

ABSTRACT 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

ABSTRACT 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

ABSTRACT 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

ABSTRACT 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

ABSTRACT 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

ABSTRACT 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

ABSTRACTCytokinesis 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

ABSTRACT 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

ABSTRACT 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

ABSTRACTMt. 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

ABSTRACTObservations 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

ABSTRACTSexual 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

ABSTRACTParamylon 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

ABSTRACTExcised 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

ABSTRACTAcclimation 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

ABSTRACTThe 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.