bluuebunny/crossref_metadata_2025_split huggingface dataset:
A COMPARISON OF AIR AND WATER AS ENVIRONMENTS FOR PHOTOSYNTHESIS BY THE INTERTIDAL ALGA FUCUS SPIRALIS (PHAEOPHYTA)1
Authors: Madsen Tom V. , Maberly Stephen C. 
Published: October 2004

ABSTRACTThe response of photosynthesis and respiration of the intertidal brown alga Fucus spiralis L. to light and temperature at ambient and elevated concentrations of inorganic carbon was investigated. The light‐saturated rate of photosynthesis was greater in air at 15° C and 20° C, but greater in water at 10° C. Light compensation point and Ik was about 50% lower under submerged relative to emerged conditions, whereas the initial slope of photosynthesis versus irradiance was higher, except at 20° C. Under both submerged and emerged conditions light‐saturated photosynthesis was limited to a similar degree (78%, and 65%, respectively) by the availability of inorganic carbon at naturally occuring concentrations. In air, slight desiccation at tissue water contents of about 96% to 92% caused a stimulation in the rate of net photosynthesis to 110–148% of fully hydrated fronds. At lower water contents the rate of net photosynthesis declined linearly with decreasing water content and became zero at a water content of about 15%. Dark respiration declined linearly with tissue water content and remained positive to a water content of 8%. Upon reimmersion the fronds showed a complete recovery within 35 min following desiccation to a water content of 20–30%. Thus F. spiralis seems to be very tolerant to desiccation. Since F. spiralis photosynthesizes effectively in air, even at a higher rate than in water as long as it has not lost a large proportion of its water in desiccation, the alternating exposure to air may be beneficial by increasing the daily carbon gain compared to a fully submerged situation.
LIGHT‐DEPENDENT DECLINE OF NH4+ ASSIMILATION UNDER CO2 DEPRIVATION IN N‐LIMITED CHLORELLA SOROKINIANA (CHLOROPHYCEAE)1
Authors: Rigano Vittoria Di Martino , Vona Vincenza , Esposito Sergio , Di Martino Catello , Rigano Carmelo 
Published: October 2004

ABSTRACTCells of Chlorella sorokiniana Shihira & Krauss 211/8k, grown in a chemostat under conditions of nitrate limitation, assimilated ammonium in light (307 ± 12 μmol · mL packed cell volume (pcv)−1· h−1) and darkness (305 ± 30 μmol · mL pcv−1· h−1) at similar rates when supplied with air containing 5% CO2. Ammonium assimilation in cell suspensions flushed with pure nitrogen to establish anaerobic conditions was almost totally prevented both in darkness and in light. Cell suspensions flushed with CO2−‐free air and grown in the dark assimilated ammonium at a rate of 314 ± 23 μmol · mL pcv−1· h−1. Light assimilation was 128 ± 10 μmol · mL pcv−1· h−1, a rate which was only 41% of that in darkness. Resupply of ammonium to N‐limited chemostat cells resulted in a 3.5‐fold stimulation of dark respiration and a suppression of photosynthetic O2 evolution. We hypothesize that the partial decline of ammonium assimilation in Chlorella 211/8k in the light under conditions of limited CO2 supply is due to the fact that the photosynthetic carboxylation reaction competes with the dark carboxylation reaction for the available CO2, and that the production of C4 and C5 precursors foramina acid biosynthesis will be slower than in the dark. Alternatively we suggest that an increase in the concentration of photogenerated compound(s) not used for CO2 assimilation attains an intracellular level suitable to trigger a control mechanism operating at the level of starch break‐down or glycolysis.
TRIGLYCERIDE ACCUMULATION AND FATTY ACID PROFILE CHANGES IN CHLORELLA (CHLOROPHYTA) DURING HIGH pH‐INDUCED CELL CYCLE INHIBITION1
Authors: Guckert James B. , Cooksey Keith E. 
Published: October 2004

ABSTRACTAlkaline pH stress resulted in triglyceride (TG) accumulation in Chlorella CHLOR1 and was independent of medium nitrogen or carbon levels. Based on morphological observations, alkaline pH inhibited autospore release, thus increasing the time for cell cycle completion. Autospore release has been postulated to coincide with TG utilization within the microalgal cell division cycle. The alkaline pH stress affected lipid accumulation by inhibiting the cell division cycle prior to autospore release and, therefore, prior to TG utilization. Cells inhibited in this manner showed an increase in TG accumulation but a decrease in both membrane lipid classes (glycolipid and polar lipid). Unlike TG fatty acid profiles, membrane lipid fatty acid profiles were not stable during TG accumulation. The membrane profiles became similar to the TG, i.e. less unsaturated than in the membrane lipids of unstressed control cells.
ULTRASTRUCTURF OF FERTILIZATION IN LAMINARIA ANGUSTATA (PHAEOPHYTA, LAMINARIALES) WITH EMPHASIS ON THE BEHAVIOR OF CENTRIOLES, MITOCHONDRIA AND CHLOROPLASTS OF THE SPERM1
Authors: Motomura Taizo 
Published: October 2004

ABSTRACTFertilization and zygote development in Laminaria angustata Kjellman were observed ultrastructurally. Cell wall formation of the zygote is initiated immediately after plasmogamy. The zygote begins to elongate, chloroplasts move from the renter to the periphery, and the sperm nucleus moves toward the egg nucleus. Karyogamy occurs with both euchromatin‐rich female nucleus and hetero‐chromatin‐rich male nucleus in interphase. Cytoplasmic inheritance of centrioles, mitochondria and chloroplasts was examined, especially during zygote development of L. angustata. Two pairs of centrioles originating from the egg and sperm exist in the early zygote. Later, egg centrioles disappear and only sperm centrioles remain resulting in one pair of centrioles in the zygote. When mitosis of the zygote is initiated, the centrioles of the pair separate and are duplicated as they migrate to the poles, in a manner similar to that in brown algal mitosis. Sperm mitochondria are enclosed with endoplasmic reticulum (ER) and Golgi vesicles. The vesicles finally become single‐membrane vesicles, and enclosed mitochondria are digested. Small sperm chloroplasts do not fuse with egg chloroplasts, increase in size, or divide and can be detected even at the stage of two‐celled sporophytes. Therefore, almost all chloroplasts of the zygote and sporophyte originate from the egg.
DIRECT OBSERVATIONS ON FLAGFLLAR TRANSFORMATION IN MALLOMONAS SPLENDENS (SYNUROPHYCEAE)1
Authors: Beech Peter L. , Wetherbree Richard 
Published: October 2004

ABSTRACTInterphase cells of Mallomonas splendens (G. S. West) Playfair have two basal bodies: BB1 bears no flagellum, and BB2 produces a mastigoneme‐bearing, anteriorly directed flagellum (F2). Light microscopy of live cells undergoing mitosis and cytokinesis showed that two small flagella arise adjacent to F2 at preprophase. These new flagella commenced beating soon after their emergence and elongated as F2 shortened. By metaphase the new flagella were en. 12 μm long, and their bases had moved to either side of the metaphase plate. The shortening F2 segregated with one of the new flagella. At early cytokinesis the new flagella were ca. 15 μm long and the parental F2 had completely retracted so that its basal body (BB2) was transformed into a BB1. A similar pattern of events is described for Mallomonas papillosa Harris & Bradley. We conclude that the mastigoneme‐bearing flagellum in Mallomonas spp. is produced from first generation basal bodies. This flagellum entirely retracts during the next mitosis so that its basal body becomes a BB1. BB1 remains as such for subsequent generations.
THE FLAGELLAR APPARATUS OF MALLOMONAS SPLENDENS (SYNUROPHYCEAE) AT INTERPHASE AND ITS DEVELOPMENT DURING THE CELL CYCLE1
Authors: Beech Peter L. , Wetherbee Richard 
Published: October 2004

ABSTRACTThe interphase configuration of the flagellar apparatus of Mallomonas splendens (G. S. West) Playfair displays several features that are novel in the Synurophyceae. One of the two basal bodies usually has no flagellum, and two fibrous bands connect the basal bodies. Surrounding the basal bodies is a distinctive, fibrous capsule which is continuous with a thick, fibrous band that constitutes the anterior portion of the rhizoplast. The remainder of the rhizoplast spreads over the nuclear apex as numerous, prominently striated straps. A single, three‐membered, mi‐crotubular root (R1) forms a loop at the cell anterior and then descends from the loop to abutt on the rhizoplast near the nuclear apex. The descending portion of R1 displays at least two orientations with respect to the basal bodies.Two new basal bodies appear before mitosis and bear the rudiments of new Ills. At preprophase these new roots are 2–3 μm long, and new rhizoplasts, which organize (nucleate?) microtubules of the incipient mitotic spindle, arise from the proximal end of the new basal bodies. The latter produce new fiagella as the parental flagellum shortens. Simultaneous to these developments is the disassembly of the parental rhizoplast and the descending portion of the parental RI. At metaphase the two pairs of basal bodies have separated so that each pair consists of a parental and a daughter basal body. The parental R1 loop is absent and the new R1s form semi‐loops around each pair of basal bodies. The rhizoplasts extend down either side of the nuclear material as the spindle becomes fully formed. The new loops are completed at mid‐cytokinesis. At the end of cytokinesis the roots elongate towards the nuclear apex, and each rhizoplast takes on the interphase appearance. Mitosis in M. splendens is compared to that in the Chrysophyceae.
FINE STRUCTURE OF THE FLAGELLAR APPARATUS OF UROGLENA AMERICANA (CHRYSOPHYCEAE)1
Authors: Owen Heather A. , Stewart Kenneth D. , Mattox Karl R. 
Published: October 2004

ABSTRACTThe three‐dimensional structure of the flagellar apparatus of Uroglena americana Calkins (Uroglenopsis americana [Calkins] Lemmerman) was determined using serial section reconstruction. The three microtubular rootlet systems (R2, R3, and R4) follow the general pattern found in other chrysophytes. The R2 rootlet originates between the basal bodies of the mastigoneme‐bearing long flagellum (F1) and the short smooth flagellum (F2) and is attached to the former by a fibrous connection. The R3 rootlet system originates as a trough‐shaped band of six microtubules spanning the distance between the proximal ends of the F1 and F2 basal bodies. The six‐membered rootlet splits into two parts (designated R3 and R3) which circle the depression from which the F2 flagellum emerges in counter‐clockwise direction. These two rootlets pass beneath the F2 basal body and descend into the cell alongside the chloroplast. The R4 rootlet originates in fibrous material which passes diagonally over the F2 basal body, forms a clockwise loop about three‐quarters of the way around the depression, and ends in the cytoplasm.In place of a typical chrysophyte R1 rootlet, U. americana has a different array of microtubules attached to the F1 basal body which we have designated the descending rootlet (DR). This rootlet is a hairpin‐shaped structure lying just below the surface of the cell; its longitudinal axis is predominantly parallel to the longitudinal axis of the cell. The DR resembles the bypassing rootlet which occurs in phaeophyte zoospores. Other chrysophytes may possess rootlets which are similar to the DR found in Uroglena.
SEXUAL REPRODUCTION IN THE FRESHWATER DINOFLAGELLATEGLOEODINIUM MONTANUM1
Authors: Kelley Ingrid , Pfiester Lois A. 
Published: October 2004

ABSTRACTThe sexual life cycle ofGloeodinium montanumKlebs was examined with light and scanning electron microscopy. In unialgal culturesG. montanumdivided predominantly by simple division, giving rise to two nonmotile cells. When placed in fresh medium, 2–4 biflagellated swarmers were formed from the vegetative cells. Swarmers developed directly into vegetative cells or acted as gametes. Both isogamy and anisogamy were observed.Gloeodinium montanumis homothallic. Fusion occurred in the non‐motile state producing a large aplanozygote, which germinated after approximately two months to a year or more. Zygote germination liberated four aplanospores. Budding of the zygote, resulting from unequal division of the protoplast and multiple fusion attempts also were observed.
LIGHT‐HARVESTING PIGMENT‐PROTEIN COMPLEXES OF THE ULVOPHYCEAE (CHLOROPHYTA):CHARACTERIZATION AND PHYLOGENETIC SIGNIFICANCE1
Authors: Fawley Marvin W. , Douglas Cheryl A. , Stewart Kenneth D. , Mattox Karl R. 
Published: October 2004

ABSTRACTPhotosystem II light‐harvesting complexes were isolated from a number of ulvophycean algae. Some of these light‐harvesting complexes displayed unusual features, most notably a high apparent molecular weight (ca. 58,000) when isolated by lithium doderyl sulfate polyarrylamide gel electrophoresis. Other ulvophycean light‐harvesting complexes had a low‐molecular weight (ca. 30,000). The distribution of the high‐molecular weight complex was limited to certain members of the Caulerpales and Blastophysa rhizopus (Siphanocladales). Within the Caulerpales, there were also spectral differences between the high‐molecular weight and low‐molecular weight light‐harvesting complex types. The differences in light‐harvesting complexes in the Ulvophyceae suggest that there are two lines of evolution in the Caulerpales and that Blastophysa may be an intermediate between the Siphon‐ocladales and the Caulerpales.
A SEX DETERMINING MECHANISM IN THE CLOSTERIUM EHRENBERGII (CHLOROPHYTA) SPECIES COMPLEX1
Authors: Kasai Fumie , Ichimura Terunobu 
Published: October 2004

ABSTRACTHomozygous mt−/mt− diploid clones of the Closterium ehrenbergii Menegh. ex Ralfs species complex were obtained by hypertonic treatment from minus vegetative cells, and mating type segregation ratios in the F1 progeny of “triploid” zygospores between wild type mt+ haploid and mt−/mt− homozygous diploui were analyzed. The ratio of plus to minus individuals was 1:4.8, and the ratio of the pairs of opposite mating types to those of minus mating type was 1:2.1. The results clearly show that mt− is dominant to mt+ and that the mating type inheritance in these zygospores follows the triploid‐like pattern. The validity of our assumption that the two mating types are determined by one genetic factor (mt− allele dominant) was confirmed in B1 progeny analyses as well. The results suggest that this sex determining mechanism is working effectively in the C. ehrenbergii species complex, in which several biological species have evolved through polyploidization.
SEASONAL PRIMARY PRODUCTION OF UNDERSTORY RHODOPHYTA IN AN UPWELLING SYSTEM1
Authors: Levitt Graham J. , Bolton John J. 
Published: October 2004

ABSTRACTThe in situ primary production of three common under‐story members of the Rhodophyta in South African west coast kelp beds was determined monthly for a year using dissolved oxygen techniques. Strong seasonal patterns of photosynthesis and respiration were evident in all three species. Net photosynthesis of all three species was greatest in spring (October) and lowest in winter (June). Increasing photosynthesis in late winter coincided with increasing ambient irradiance and photoperiod, whereas decreasing photosynthesis in summer was not explained by changes in the environmental parameters measured. We suggest that this may he due to an innate pattern related to some other seasonal plant activity such as reproduction. Seasonal Pmaxand Ikvalues reveal that the obligate understory species,B. proliferaandE. obtusa,are shade‐adapted whereasG. radula,a low intertidal and shallow subtidal dominant, is sun‐adapted. Low C: X ratios consistent with a high nutrient environment and high rates of productivity were found in all three species. Net photosynthesis to respiration (Pn:R) ratios were fairly constant forB. proliferaandE. obtusa,implying that then photosynthetic processes were governed more by seasonal variations in irradiance than by instantaneous light availability. The Pn: R ratio ofG. radulawas variable, suggesting that this species is more responsive to rapid fluctuations in irradiance and may therefore be adapted for rapid growth during periods of high irradiance.
LIGHT AND NUTRIENT LIMITATION OF SEA‐ICE MICROALGAE (HUDSON BAY, CANADIAN ARCTIC)1
Authors: Gosselin Michel , Legendre Louis , Therriault Jean‐Claude , Demers Serge 
Published: October 2004

ABSTRACTChanges in the biochemical composition of sea‐ice microalgae (southeastern Hudson Bay, Canadian Arctic) were used to assess the light and nutrient status of cells growing at the ire‐water interface. These changes allowed us to test the hypothesis that ire algae are limited by light at the beginning of their growth season and become periodically limited by nutrients as the season progresses. During the vernal growth season, three patterns of variation in cellular components were found in response to changes in environmental conditions. 1) Chlorophyllsaandc,ATP, carbohydrate, and carbon followed the seasonal increase in under‐ice irradiance, which was mainly mused by melting of the snow cover. 2) Dissolved and biogenic silicon underwent periodic variations, which were coupled to the fortnightly neap‐spring cycle of tidal mixing. 3) Cellular contents of free amino acids, protein, and total nitrogen remained relatively constant during the season. An early decrease in intracellular chlorophyllsaandcsuggests that ire algae did respond to small changes in solar irradiance by changing the pigment composition of their photosynthetic units. Seasonal increases in ATP, carbohydrate, and total carbon indicate light limitation in April, followed in May by a period of excess irradiance and/or nutrients in short supply. The seasonal increase in ATP and the high values of the ratio free amino acids: protein show that neither phosphorus nor nitrogen limited algal growth at the ire‐water interface. In May, higher values of carbohydrate: protein, carbon: nitrogen, carbon: chlorophylla,and also carbon: silicon and ATP: silicon indicate that the ice algae became silicon‐deficient in their natural environment. Following a period of light limitation, at the beginning of the season, ice‐algal growth became silicon‐limited, when in situ irradiance and the accumulated algal biomass were high and the tidally‐driven nutrient supply was not strong enough to satisfy algal nutrient requirements.
PHOTOSYNTHETIC RESPONSES TO LIGHT AND TEMPERATURE OF THE HETEROMORPHIC MARINE ALGAMASTOCARPUS PAPILLATUS(RHODOPHYTA)1
Authors: Zupan John R. , West John A. 
Published: October 2004

ABSTRACTPhysiological differentiation of the heteromorphic life‐history phases of the red algaMastocarpus papillatus(C. Agardh) Kützing was assessed. Photosynthetic responses to light and temperature of the erect, foliose gametophyte were compared to those of the crustose tetrasporophyte. Plants of both phases were collected from four locations on the Pacific coast of Baja California, Mexico, and California, USA, between 32–4l° N latitude. Within each location, the chlorophyll‐specific, light‐saturated photosynthetic rates of gametophytes were generally five times greater than those of tetrasporophytes. Initial slopes of photosynthesis: irradiance curves were greater for gametophytes than for tetrasporophytes. The crust and the blade from each location were similar with respect to dark respiration rates. For tetrasporophytes from all locations, the photosynthetic temperature optima were between 12–15° C. The photosynthetic temperature optima for gametophytes ranged from 15–17° C for plants from Trinidad Head (41° N) to 22–25° C for plants from Punta Descanso (32° N). Both gametophytes and tetrasporophytes from the northernmost location had significantly higher photosynthetic rates than the same phase from the other three locations. The photosynthetic responses to light support models for the life history in which life history phases have different ecological roles. The gametophyte, thought to be specialized for rapid growth and competition, may allocate more resources to photosynthetic machinery, hence the higher maximum photosynthetic rates. The tetrasporophyte, thought to be specialized for resistance to herbivores, may allocate more resources to structural or chemical defenses in preference to photosynthetic machinery. Consequently, the tetrasporophyte has lower photosynthetic capacity.
INFLUENCE OF VARIOUS EXPOSURE PERIODS ON THE BIOMASS AND CHLOROPHYLL A OF CLADOPHORA GLOMERATA (CHLOROPHYTA)1
Authors: Usher Howell D. , Blinn Dean W. 
Published: October 2004

ABSTRACTThe biomass of Cladophora glomerata (L.) Kütz. was estimated at selected sites in the Colorado River between Glen Canyon Dam, Arizona, and River Kilometer 354. C. glomerata biomass was significantly higher at sites above Lees Ferry (25 km downstream from the Dam) than sites below the Ferry. Biomass and chlorophyll a were significantly reduced when C. glomerata was subjected to one‐time exposures to the atmosphere for 12 daylight h in more. Repeated 12/12 h and 24/24 h (exposure/submergence) cycles over a two‐week period also showed a significant reduction in biomass. The adaptations of C. glomerata to “stranding” during regulated flows are discussed.
CHANGES IN CELL CHEMICAL COMPOSITION DURING THE LIFE CYCLE OF SCRIPPSIELLA TROCHOIDEA (DINOPHYCEAE)1
Authors: Lirdwitayaprasit Thaithaworn , Okaichi Tomotoshi , Montani Shigeru , Ochi Tadashi , Anderson Donald M. 
Published: October 2004

ABSTRACTThe cellular content of carbon, nitrogen, amino acids, polysaccharides, phosphorus and adenosine trtphosphate (ATP) was determined at several stages during the life cycle of the dinoflagellate Scrippsiella trochoidea (Stein) Loeblich. Carbon per cell decreased slightly between exponential and stationary phase growth in vegetative cells whereas nitrogen per cell did not change. Both of these cellular components increased markedly on encystment and then decreased to vegetative cell levels during dormancy and germination. C/N ratios increased gradually during cyst dormancy and activation, reflecting a more rapid decrease in N than in C pools, even though both decreased through time. Amino acid composition was relatively constant during the vegetative cell stages; glutamic acid was the dominant component. Arginine was notably higher in cysts than in vegetative cells but decreased significantly during germination, suggesting a role in nitrogen storage. The ratio of neutral ammo acids to total ammo acids (NAA/TAA) decreased as cysts were formed and then gradually increased during storage and germination. The ratio of basic ammo acids to total ammo acids (BAA/TAA) changed in the opposite direction of NAA/TAA, whereas the ratio of acidic acids to total amino adds (AAA/TAA) was generally invariant. Ammo acid pools were not static during the resting slate in the cysts: there was degradation or biosynthesis of certain, but not all, classes of these compounds. The monosacchande composition of cold and hot water extracted polysaccharides was quite different between cells and cysts. A high percentage of glucose in cysts suggests that the storage carbohydrate is probably in the form of glucan. Total cellular phosphorus was higher in all cyst stages than in vegetative cells. However, ATP‐cell−1 decreased as vegetative cells entered stationary phase and encysted, and continued to decrease in cysts during dark cold storage. ATP increased only as the cysts were activated at warm temperatures in the light and began to germinate. The above data demonstrate that dormancy and quiescence are not periods of inactive metabolism but instead are times when numerous biochemical transformations are occurring that permit prolonged survival in a resting state.