bluuebunny/crossref_metadata_2025_split huggingface dataset:
GROWTH CHARACTERISTICS OF PHYTOPLANKTON DETERMINED BY CELL CYCLE PROTEINS: PCNA IMMUNOSTAINING OF DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1
Authors: Lin Senjie , Chang Jeng , Carpenter Edward J. 
Published: October 2004

ABSTRACT By immunohistochemistry and immunofluorescence methods, we observed that the analog of proliferating cell nuclear antigen (PCNA) in Dunaliella tertiolecta Butcher (Chlorophyceae) was exclusively located in the nucleus. Among positively stained cells, PCNA abundance varied, being highest in S‐phase cells, lower in others, and undetectable in early G1‐ or late M‐phase cells. In exponentially growing and partially synchronized cultures, the percentage of PCNA‐stained cells (% PCNA‐stained cells) oscillated in the photocycle (12:12 h LD). It increased during the light period and reached a peak (75%) before the onset of the dark period when the culture was mainly (71%) in the S phase of the cell cycle. The DNA synthesis inhibitor, hydroxyurea, depressed PCNA abundance, whereas no effect was detected for the mitosis inhibitor colchicine. We conclude that PCNA in D. tertiolecta is associated with the S phase of the cell cycle where it is accumulated and functioning. PCNA was used to characterize the growth pattern of cultures grown in different media, temperatures, and growth stages. The time lag between the PCNA‐stained phase and the M phase was very short in a continuous culture grown in reduced f/2 medium at 22°C and was considerably longer in the cultures grown in f/2 at 15°C. When an exponentially growing culture grew older, % PCNA‐stained cells decreased. In a late stationary culture where there was no net growth, a small number of cells were still cycling through the PCNA‐stained phase and cell division. In the continuous culture grown at 22°C, the duration of the PCNA‐stained phase (Ts) was 13 h. Calculations with this Ts and % PCNA‐stained cells yielded a growth rate of 0.77 d−1, which was close to that obtained by cell counts (0.69 d−1). Taken together, the results suggest that PCNA is a useful indicator of growth status and a promising cell cycle marker for estimation of species‐specific growth rate.
EFFECTS OF BROMIDE AND IODIDE ON STALK SECRETION IN THE BIOFOULING DIATOM ACHNANTHES LONGIPES (BACILLARIOPHYCEAE)1
Authors: Johnson Lisa M. , Hoagland Kyle D. , Gretz Michael R. 
Published: October 2004

ABSTRACT Extracellular polymeric substance (EPS) secretion was examined in the stalked marine diatom Achnanthes longipes Ag. in defined medium. This common biofouling diatom exhibited an absolute requirement for bromide for stalk production and substratum attachment, whereas elevated iodide concentrations in the growth medium inhibited stalk formation and adhesion. Varying EPS morphologtes resulted from altering bromide and iodide levels: pads, stalk‐pads, stalks, and no EPS. Cells showed no differences in growth with bromide or iodide concentrations, indicating that they were not physiologically stressed under conditions that impaired EPS secretion. Cells grown in elevated iodide secreted significantly more soluble extracellular carbohydrate into the medium, suggesting that the EPS was soluble and unable to be polymerized into a morphologically distinct gel. By replacing sulfate with methionine, the diatom lost its ability to form stalks even in the presence of bromide, indicating that free sulphate may be required for proper cross‐linking of stalk polymers. Lotus‐FITC, a fluorescent‐tagged lectin, preferentially labeled the EPS and, thus, was used to visualize and quantify EPS secretion along a bromide gradient in conjunction with an image analysis system. This technique demonstrated a direct correlation between the amount of bromide present in the medium and the specific EPS morphology formed.
PHYLOGENY OF AUREOCOCCUS ANOPHAGEFFERENS AND A MORPHOLOGICALLY SIMILAR BLOOM‐FORMING ALGA FROM TEXAS AS DETERMINED BY 18S RIBOSOMAL RNA SEQUENCE ANALYSIS1
Authors: DeYoe Hudson R. , Chan Amy M. , Suttle Curtis A. 
Published: October 2004

ABSTRACT The 18S ribosomal RNA genes from isolates of the east coast “brown tide” alga Aureococcus anophagefferens (strain Pt‐1) and the Texas “brown tide” alga (strain TBA‐2) were sequenced and compared to the gene sequences of Pelagomonas calceolata, a member of the Pelagophyceae, and 10 other organisms. The genes of A. anophagefferens and strain TBA‐2 consisted of 1814 and 2236 bases, respectively. The difference in length was largely due to a 423‐base insert occurring in the gene of strain TBA‐2. Excluding the insert, 93% of the bases of the aligned sequences were identical. Phylogenetic analyses were performed based on two different alignment refinement methods (eye refinement and Gatesy refinement). Trees inferred from the Jukes‐Cantor distance matrices using the neighbor‐joining method were similar for both alignment methods. In both trees, A. anophagefferens, strain TBA‐2, and P. calceolata formed a monophyletic group with A. anophagefferens and P. calceolata being sister taxa and strain TBA‐2 occurring on a deeper‐rooted branch. Bootstrap data sets for both alignment methods gave strong support for the Pelagophyceae group and the branches within that group. Parsimony analyses using the two alignments gave one tree for the eye‐refined alignment and two trees for the Gatesy method. All three trees had nearly the same topology as the trees inferred from the distance method. In addition, the Pelagophyceae group and the branches within that group were supported by bootstrap analyses and decay indices. Based on the available data, A. anophagefferens and strain TBA‐2 should be placed in the Pelagophyceae but not in the same order and family as P. calceolata.
PHYLOGENETIC POSITION OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE) BASED ON SMALL SUBUNIT RIBOSOMAL RNA SEQUENCE DATA1
Authors: Sawayama Shigeki , Inoue Seiichi , Yokoyama Shin‐ya 
Published: October 2004

ABSTRACT A small subunit ribosomal RNA (16S‐like rRNA) in the hydrocarbon‐rich microalga Botryococcus braunii Kützing (Chlorophyceae) was amplified using RNA polymerase chain reaction, and its sequence was determined. The sequence data of B. braunii were analyzed with those of several other algae in order to determine phylogenetic relationships among these algae. Phylogenetic analysis indicated B. braunii to be a member of the Chlorophyta and possibly related to Characium vacuolatum and Dunaliella parva.
OBSERVATIONS ON A CHAMAESIPHONACEOIS ALGA (CYANOPHYCEAE) WITH SPECIAL REFERENCE TO EXOCYTE FORMATION1,2
Authors: Rosowski James R. , Bielik Ivan , Lee Kit W. 
Published: October 2004

ABSTRACT A unicellular cyanophycean culture contaminant had features of both Geitleribactron Kom. and Cyanophanon Geitl. The cells were elongated, sheathless, mostly similar in diameter throughout their length, and attached polarly in rosettes or groups and produced only a single elongated exocyte (=exospore). Young cells were moderately elongated and resembled Geitleribactron. As cells aged, they greatly elongated and then resembled Cyanophanon. Some cells formed Y‐shaped bifurcations, features of C. mirabile Geitl. and C. minus Geitl., but they lacked the basal sheath (pseudovagina) of C. mirabile. During exocyte formation, a thick and localized L‐II wall layer protuberance extended the exocyte away from the parent cell. This terminal wall thickening then appeared to move to one side from subsequent and unequal cell wall growth. Cells sovnetimes bent abruptly, occasionally opposite a thickening in the L‐II wall layer. Further studies in culture of putative Geitleribactron and Cyanophanon isolates are necessary to ascertain the breadth of their structural diversity and the identity of the present taxon.
GOMPHONEIS MESTA (BACILLARIOPHYTA). II. MORPHOLOGY OF THE INITIAL FRUSTULES AND PERIZONIUM ULTRASTRUCTURE WITH SOME INFERENCES ABOUT DIATOM EVOLUTION1
Authors: Passy‐Tolar Sophia I. , Lowe Rex L. 
Published: October 2004

ABSTRACT The morphology of initial frustules of Gomphoneis mesta Passy‐Tolar & Lowe was studied with light and scanning electron microscopy The structure of the raphe, central nodule, stigma, striae, and apical pore field in post‐auxospore generations was described. Discovery of internal chambers and an axial plate in very early stages of the life cycle of G. mesta reveals a possible evolutionary connection with the Herculeana group (sensu Kociolek and Stoermer 1989) and suggests that the loss of axial plates is a secondary event. Polarization of the characters “stigma number” and “outline of the internal stigmal opening” is proposed. A perizonium, composed of transverse and longitudinal bands, is reported for the first time in the genus Gomphoneis.
CYTOMORPHOLOGICAL CHARACTERIZATION OF THE PLANKTONIC DIAZOTROPHIC CYANOBACTERIA TRICHODESMIUM SPP. FROM THE INDIAN OCEAN AND CARIBBEAN AND SARGASSO SEAS1
Authors: Janson Sven , Siddiqui Pirzada J. A. , Walsby Anthony E. , Romans Kristen M. , Carpenter Edward J. , Bergman Birgitta 
Published: October 2004

ABSTRACTTrichodesmium Ehrenberg species were collected in the Caribbean Sea, Sargasso Sea, and coastal areas of Tanzania (Indian Ocean). The specimens were divided into five species on the basis of morphometric characters such as cell dimensions and colony formation: T. tenue Wille, T. erythraeum Ehrenberg, T. thiebautii Gomont, T. hildebrandtii Gomont, and T. contortum Wille. In addition, Trichodesmium sp., a spherical colony of uncertain taxonomic position was examined. The cell structure of each species was investigated by means of light, scanning electron, and transvnission electron microscopy. Particular attention was paid to the presence and ultrastructural arrangement of gas vacuoles and glycogen fiber clusters (GFCs). This resulted in identification of two major groups of species: 1) T. tenue, Trichodesmium sp. with spherical‐shaped colonies, and T. erythraeum with GFCs and more or less localized gas vacuoles; and 2) T. thiebautii, T. hildebrandtii, and T. contortum lacking GFCs and with gas vacuoles spread at random. The species within each group were further characterized with respect to the dimension of the gas vesicles, cylindrical bodies, scroll bodies, and a new cellular inclusion body, Differences in colony formation and cell dimensions correlated with specific ultrastructural characters in five of the six forms. This is the first ultrastructural study comparing different forms of Trichodesmium sampled at geographically remote areas and shows that one species appears identical regardless of the sampling site. Some of the species had not been investigated earlier, and probably more species are to be identified and analyzed.
EFFECTS OF SHADING BY ADULTS ON THE GROWTH OF BLADE‐STAGE MACROCYSTIS PYRZFERA (PHAEOPHYTA) DURING AND AFTER THE 1982–1984 EL NIÑO1
Authors: Schroeter Stephen C. , Dean Thomas A. , Thies Karl , Dixon John D. 
Published: October 2004

ABSTRACT The effect of shading by an adult canopy on blade‐stage Macrocystis pyrifera (L.) C. A. Agardh was estimated by comparing the average growth rate of individuals under a canopy to that of individuals in a canopy gap. This comparison was made in 1983 during a strong El Niño and again in 1986 after the El Niño. Estimated nutrient concentrations in 1983 were two orders of magnitude below those in 1986, whereas ambient light levels were over 3 times higher. The kelp canopy caused similar proportional light reductions (20–30%) during both years. Blades grew 18% slower under the canopy than in the clearing in 1983 and about 77% slower under the canopy in 1986. Blade‐stage individuals grew at the same rates in clearings in 1983 and 1986. Regardless of shading, the average growth rate of blade‐stage kelp under the ambient, low‐nutrient conditions of 1983 was higher than that later observed for multifronded juveniles during the same El Niño. The growth of blade‐stage kelp was more like that of larger juveniles growing under high‐nutrient conditions. The difference may be due to greater concentrations of nutrients very near the sea floor where single blades are growing compared to concentrations higher in the water column where larger kelp have most of their tissues.
PHOTOSYNTHETIC CHARACTERISTICS OF THE COCCOLITHOPHORID EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) EXPOSED TO ELEVATED CONCENTRATIONS OF DISSOLVED INORGANIC CARBON1
Authors: Nielsen Marianne V. 
Published: October 2004

ABSTRACT Light‐saturated photosynthesis (Pmax) of Emiliania huxleyi (Lohmann) Hay et Mohler is known to be carbonlimited at natural concentrations of dissolved inorganic carbon (DIC). In the present study, light‐limited and light‐saturated photosynthetic rates of E. huxleyi were studied at three concentrations of DIC (2.4, 7.4, and 12.4 mM) for high‐calcite (Cin/Ctot=0.48) and low‐calcite (Cin/Ctot=0.08) cells of the same strain. The photosynthetic efficiency (α) and the maximum quantum yield (θmax)A increased by more than a factor of 2 from the lowest to the highest DIC level. Pmax a, and θmax were always higher for the high‐calcite than for the low‐calcite cells at identical DIC levels. This may indicate that the calcifcation process acts as an extra supplier of CO2 for photosynthesis making the CO2 shortage at natural DIC levels a little smaller for high‐calcite than for low‐calcite E. huxleyi. A dependency of θmax on DIC has not previously been shown for marine phytoplankton. θmax is a key parameter in recent biooptical models of phytoplankton productivity, and the results from the present study are therefore important for modeling the productivity of E. huxleyi.
TEMPERATURE AND IRRADIANCE EFFECTS ON GROWTH OF PITHOPHORA OEDOGONIA (CHLOROPHYCEAE) AND SPIROGYRA SP. (CHAROPHYCEAE)1
Authors: O'Neal Steven W. , Lembi Carole A. 
Published: October 2004

ABSTRACT Growth responses of Pithophora oedogonia (Mont.) Wittr. and Spirogyra sp. to nine combinations of temperature (15°, 25°, and 35°C) and photon flux rate (50, 100, and 500 μmol·m−2·s−1) were determined using a three‐factorial design. Maximum growth rates were measured at 35°C and 500 pmol·m−2·s−1 for P. oedogonia (0.247 d−1) and 25°C and 500 μmol·m−2·s−1 for Spirogyra sp. (0.224 d−1). Growth rates of P. oedogonia were strongly inhibited at 15°C (average decrease= 89%of maximum rate), indicating that this species is warm stenothermal. Growth rates of Spirogyra sp. were only moderately inhibited at 15° and 35°C (average decrease = 36 and 30%, respectively), suggesting that this species is eurythermal over the temperature range employed. Photon flux rate had a greater influence on growth of Spirogyra sp. (31% reduction at 50 pmol·m−2·s−1 and 25°C) than it did on growth of P. oedogonia (16% reduction at 50 μmol·m−2·s−1 and 35°C). Spirogyra sp. also exhibited much greater adjustments to its content of chlorophyll a (0.22–3.34 μg·mg fwt−1) than did P. oedogonia (1.35–3.08 μg·mg fwt−1). The chlorophyll a content of Spirogyra sp. increased in response to both reductions in photon flux rate and high temperatures (35°C). Observed species differences are discussed with respect to in situ patterns of seasonal abundance in Surrey Lake, Indiana, the effect of algal mat anatomy on the internal light environment, and the process of acclimation to changes in temperature and irradiance conditions.
SEASONAL VARIATIONS IN PHOTOSYNTHESIS‐IRRADIANCE RESPONSES BY BIOFILMS IN MEDITERRANEAN STREAMS
Authors: Guasch Helena , Subater Sergi 
Published: October 2004

ABSTRACT The relationships between primary production and irradiance were analyzed over an annual cycle in natural biofilms of two undisturbed streams: La Solana (LS), an open calcareous stream, and Riera Major (RM), a shaded siliceous stream. In LS, low photosynthetic efficiency (αchl and αarea) and high values of both the light saturation parameter (Ik) and the carotenoid/chlorophyll ratio indicated adaptation to high light regimes. On the other hand, higher photosynthetic efficiency and lower Ik as well as photoinhibition at high irradiance found in the biofilms of RM indicated shade adaptation. However, the lack of correlation between light availability in nature and the photosynthetic parameters studied in the laboratory suggested that light was not the most important factor in determining seasonal changes in the photosynthetic behavior in this stream. Both in the open and shaded streams, algal patches collected simultaneously exhibited different photosynthesis‐irradiance (P‐I) curues, showing that community composition influenced the P‐I parameters. In the open stream (LS), however, significant negative correlations between αarea and chlorophyll a and between Pmaxchland chlorophyll a (r=‐0.994, P < 0.001, and r =‐0.929, P < 0.05, respectively) suggested that photosynthesis was affected by self‐shading. Due to the absence of photoinhibition in the biofilms of LS, high photosynthetic rates were maintained at the ambient high light environment, thus compensating for low photosynthesis at low irradiance. In the shaded stream (RM), because photosynthesis was saturated at low irradiances, primary production was relatively high given the low light conditions.
LIGHT RESPIRATION IN SIX ESTUARINE PHYTOPLANKTON SPECIES: CONTRASTS UNDER PHOTOAUTOTROPHIC AND MIXOTROPHIC GROWTH CONDITIONS1
Authors: Lewitus Alan J. , Kana Todd M. 
Published: October 2004

ABSTRACT The photoresponse of respiration was examined in six estuarine phytoplankton species grown at a limiting irradiance in the presence or absence of glucose. Cellular respiration rates in the dark, at the growth irradiance, and at saturating light levels were higher in glucose‐grown cultures than in photoautotrophic cultures. Glucose uptake also affected the relationship between incident irradiance and gross respiration rate, and the specific respiratory pathways that contributed to the respiration versus irradiance (R vs. I) response. The energy‐conseming Mehler reaction contributed largely to light‐stimulated respiration in photoautotrophic (energy‐limited) cultures. However, the energy‐dissipating alternative pathway was the predominant form of respiration measured in mixotrophic (energy‐sufficient) cultures. Based on these and previous observations, a model of phytoplankton R us. I response is presented, in which the relative contributions of different light respiratory processes (cytochrome pathway respiration, alternative pathway respiration, chlororespiration, Mehler reaction) are dependent on the incident irradiance and cellular energy content.
GROWTH CHARACTERISTICS OF MARINE PHYTOPLANKTON DETERMINED BY CELL CYCLE PROTEINS: THE CELL CYCLE OF ETHMODISCUS REX (BACILLARIOPHYCEAE) IN THE SOUTHWESTERN NORTH ATLANTIC OCEAN AND CARIBBEAN SEA1
Authors: Lin Senjie , Carpenter Edward J. 
Published: October 2004

ABSTRACTEthmodiscus spp. is an important contributor to oceanic tropical‐ooze sediments and thus might be an important transport vehicle of carbon from the ocean surface to sediments. The knowledge of its cell cycle and growth rate, which is still lacking, is necessary to evaluate the importance of Ethmodiscus in nutrient cycling and to solve the discrepancy between its high sedimentary abundance and rarity in the plankton. We used immunofluorescence of a cell cycle protein, prolqerating cell nuclear antigen (PCNA), and DNA‐specific staining to study the progression of the cell cycle and roughly estimate the growth rate for E. rex (Rattray) Wiseman and Hendey in the southwestern North Atlantic Ocean and Caribbean Sea in June 1994 and January 1995. During the cell division cycle, the chloroplasts appeared to synthesize DNA before the nucleus (S phase). Following the S phase, the nucleus moved from one end of the cell toward the center underneath the midline of the girdle band (G2 phase) where it divided (M phase). During a very brief period, the parent cell split and moved apart from the girdle midline, and two new valves were produced (late M phase). The two daughter nuclei apparently remained attached at the joint of the two newly produced valves, where they appeared to be responsible for coordinating the symmetrical formation of the new valves. The morphologically complete daughter cells remained joined for a short period of time before separating into solitary cells whose nucleus was located at one end of the cell. Derived from the phase fraction curves, the duration of the cell cycle phases decreased in the order from G1, S, G2, to M. A conservative estimate of the growth rate in the study area obtained by using PCNA immunostaining was 0.39–0.46 d−1 in June and 0.15 d−1 in January. The validity and implication of the growth rate estimates are discussed.
SPECIES‐SPECIFIC DIFFERENCES OF PYRENOIDS IN CHLORELLA (CHLOROPHYTA)1
Authors: Ikeda Taiji , Takeda Hiroshi 
Published: October 2004

ABSTRACT The structure of the pyrenoid supports the separation of Chlorella species into two groups based on cell wall chemistry and suggests evolutionary relationships. Chlorella species with a glucan‐type wall exhibit quite diverse pyrenoid structures, which may indicate that these species are not closely related. Those species with glucosamine cell walls (C. kessleri, C. sorokiniana, C. vulgaris) are virtually identical in pyrenoid morphology, indicating a closer evolutionary relationship. In the species with glucosamine walls, the thylakoid that penetrates into the pyrenoid matrix, is unijormly double‐layered. Pyrenoids in the species with glucan walls show various features: 1) a pyrenoid matrix only, 2) a pyrenoid traversed by a few discs of double thylakoids with many adhering pyrenoglobuli, 3) a pyrenoid penetrated with tubelike structures or 4) a pyrenoid penetrated with many single undulating thylakoids. The pyrenoid structure of the symbiotic Chlorella in Paramecium bursaria resembles those of free‐living Chlorella with glucosamine walls.
GENETIC VARIABILITY AND PARENTAGE IN MACROCYSTIS PYRZFERA (PHAEOPHYCEAE) USING MULTI‐LOCUS DNA FINGERPRINTING1
Authors: Coyer James A. , Robertson Deborah L. , Alberte Randall S. 
Published: October 2004

ABSTRACT Multi‐locus DNA fingerprints using an M13 probe were obtained for two individuals of Macrocystis pyrifera (L.) C. Ag. collected from Monterey Bay, California, and their laboratory‐reared offspring. DNA was extracted from each of two field‐collected individuals (= parents), their self‐fertilized diploid offspring (three and seven individuals), and one diploid individual resulting from spores of the two parents. A total of 20 bands (4–19 kb) was detected among all individuals, ranging from 7 to 14 bands for any one individual. Two bands were present in all individuals, and three bands were unique to one parent and its three progeny. Ten bands were observed in the out‐crossed individual, of which three were inherited from one parent, two from the other parent, and five were present in both parents. Genetic similarity between each parent and their self‐fertilized offspring was significantly higher than similarity between the two self‐fertilized groups. The data show that multi‐locus DNA fingerprints can be used to assess parentage in the giant kelp and that there is consistent agreement between genetic similarity and known genetic relatedness among parents and offspring.