bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPONTANEOUS AND STIMULATED BIOLUMINESCENCE OF THE DINOFLAGELLATE CERATOCORYS HORRZDA (PERIDINIALES)1
Authors: Latz Michael I. , Lee Andrea O. 
Published: October 2004

ABSTRACT This is the first report of spontaneous bioluminescence in the autotrophic dinoflagellate Ceratocorys horrida von Stein. Bioluminescence was measured, using an automated data acquisition system, in a strain of cultured cells isolated from the Sargasso Sea. Ceratocorys horrida is only the second dinoflagellate species to exhibit rhythmicity in the rate of spontaneous flashing, flash quantum flux (intensity), and level of spontaneous glowing. The rate of spontaneous flashing was maximal during hours 2–4 of the dark phase [i.e. circadian time (CT)16–18 for a 14:10 h LD cycle (LD14:10)], with approximately 2% of the population flashing‐min−1, a rate approximately one order of magnitude greater than that of the dinoflagellate Gonyaulax polyedra. Flash quantum flux was also maximal during this period. Spontaneous flashes were 134 ms in duration with a maximum flux (intensity) of 3.1×109 quanta‐s−1. Light emission presumably originated from blue fluorescent microsources distributed in the cell periphery and not from the spines. Values of both spontaneous flash rate and maximum flux were independent of cell concentration. Isolated cells also produced spontaneous flashes. Spontaneous glowing was dim except for a peak of 6.4× 104quanta‐s−1 cell−1, which occurred at CT22.9 for LD14:10 and at CT22.8 for LD12:12. The total integrated emission of spontaneous flashing and glowing during the dark phase was 4×109 quantacell−1, equivalent to the total stimulable luminescence. The rhythms for C. horrida flash and glow behavior were similar to those of Gonyaulax polyedra, although flash rate and quantum flux were greater. Spontaneous bioluminescence in C. horrida may be a circadian rhythm because it persisted for at least three cycles in constant dark conditions. This is also the first detailed study of the stimulated bioluminescence of C. horrida, which also displayed a diurnal rhythm. Cultures exhibited >200 times more mechanically stimulated bioluminescence during the dark phase than during the light phase. Mechanical stimulation during the dark phase resulted in 6.7 flashes. cell−1; flashes were brighter and longer in duration than spontaneous flashes. Cruise‐collected cells exhibited variability in quantum flux with few differences in flash kinetics. The role of dinoflagellate spontaneous bioluminescence in the dynamics of near‐surface oceanic communities is unknown, but it may be an important source of natural in situ bioluminescence.
DIVISION APPARATUS OF THE CHLOROPLAST IN NANNOCHLORIS BACILLARIS (CHLOROPHYTA)1
Authors: Ogawa Satoko , Ueda Katsumi , Noguchi Tetsuko 
Published: October 2004

ABSTRACT Chloroplast division in Nannochloris bacillaris Naumann (Chlorophyta) was examined by electron microscopy after preparation of samples by freeze‐substitution. A pair of belts appeared on the surface of the outer and inner envelope membranes at the middle of the chloroplast. These belts seemed to be constructed of thin fibrils that run parallel to the longitudinal direction of the belts. The outer fibrillar belt increased in width as the constriction of the chloroplast advanced. It appears that the fibrillar belt is the division apparatus of the chloroplast. It encircles the chloroplast and finally divides the chloroplast in two as the diameter of the belt decreases.
DNA:ATP RATIOS IN MARINE MICROALGAE AND BACTERIA: IMPLICATIONS FOR GROWTH RATE ESTIMATES BASED ON RATES OF DNA SYNTHESIS1
Authors: Jones David R. , Karl David M. , Laws Edward A. 
Published: October 2004

ABSTRACT DNA: ATP and carbon: DNA (C:DNA) ratios were measured in a total of 14 species of marine microalgae and bacteria. Comparison of several DNA assay methods with results obtained with cultures uniformly labeled with 33P indicated that by far the most accurate results were obtained using diaminobenzoic acid (DABA) or diphen‐ylamine, with DABA having the highest precision. Both the Hoechst and DAPI methods seriously underestimated DNA concentrations in algal cultures. Average DNA: ATP ratios in the algal and bacterial cultures were I7 and 34 by weight, respectively, with almost all values lying in the range of 10–40. DNA: ATP ratios in the microalgae showed no correlation with growth conditions but varied by about a factor of 3 among species. C:DNA ratios for individual species of microalgae and bacteria ranged from 21 to 155 by weight and averaged 50 for the microalgae and bacteria taken together. Growth rates of microalgal species grown in cyclostats were estimated to within 8% of dilution rates when calculated from the uptake of 3H‐adenine and the DNA: ATP ratio of the species. Use of the 3H‐adenine method for estimating microalgal growth rates in the field may thus be a useful tool for investigating the physiology of microalgae in nature.
DISTURBANCE OF STREAM PERIPHYTON BY PERTURBATIONS IN SHEAR STRESS: TIME TO STRUCTURAL FAILURE AND DIFFERENCES IN COMMUNITY RESISTANCE1
Authors: Biggs Barry J.F. , Thomsen Henrik A. 
Published: October 2004

ABSTRACT The resistance of stream periphyton to structural disturbance by increases in shear stress (simulating a spate) was investigated in a laboratory flow tank. We monitored loss of biomass from a filamentous community (dominated by Melosira varians) under four different levels of shear stress. In each case, any loss that was going to occur did so within 10 min for this community. In a second experiment, we tested the resistance of four different communities (two dominated by nonfilamentous diatoms and two dominated by filamentous green algae/diatoms) to increases in shear stress. Nine different levels of shear stress were used, ranging from 1‐ to 70‐fold higher than the conditions to which the communities were acclimated. All communities were 14 days old, but some differences in initial biomass occurred that influenced the degree of resistance independently of species composition. Overall, the nonfilamentous diatom communities were the most resistant, and the filamentous communities were the least resistant. The kinetics of the sloughing process varied among community types, with a community dominated by Melosira varians/Gom‐phonema parvulum losing 50% of its biomass with only a 3‐fold increase in shear stress. In contrast, a community dominated by the nonfilamentous diatoms Fragilaria vaucheriae/Cymbella minuta lost <50% of its biomass after a 70‐fold increase in shear stress. Shear stresses required for 50% loss of biomass for the different communities were as follows: 3.6 Newtons.m−2 for the Melosira varians/Gomphonema parvulum community, 10.0 N.m−2 for the Spirogyra sp./Gomphoneis her‐culeana/Ulothrix zonata community, 50.6 N.m−2 for the Fragilaria construens/Cymbella minuta/Ach‐nanthes minutissima community, and >90.0 N.m−2for the Fragilaria vaucheriae/Cymbella minuta community. These results show that spates without bedload movement can potentially have widely differing disturbance effects on periphyton loss among streams depending on the initial taxonomic composition of resident communities. These results have important implications for stream ecosystem analysis and modeling.
IDENTIFICATION OF A MYOSIN‐LIKE PROTEIN IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1
Authors: La Claire John W. , Chen Richard , Herrin David L. 
Published: October 2004

ABSTRACT A myosin‐like protein was identified in vegetative cells of the unicellular green alga Chlamydomonas reinhardtii Dangeard. Polyclonal antibodies affinity purified against the heavy chain of slime‐mold myosin recognized a 180,000 Mr protein in western blots of total protein extracts from three different strains, including cyt‐1, a cytokinesis‐defective mutant. Immunoblots of isolated chloroplasts indicated that some of the cellular myosin fractionated with chloroplasts, whereas tubulin did not. Evidence for the presence of at least one myosin gene was obtained by probing Southern blots of genomic DNA with a myosin heavy‐chain gene fragment isolated from the green alga Ernodesmis verticillata (Kützing) Børgesen. Collectively, the immunological and molecular data identify at least one myosin heavy‐chain gene and a myosin‐like protein in vegetative cells of the model organism Chlamydomonas.
A SEASONAL COMPARISON OF CARBON, NITROGEN, AND PIGMENT CONTENT IN LAMINARIA SOLIDUNGULA AND L. SACCHARINA (PHAEOPHYTA) IN THE ALASKAN ARCTIC1
Authors: Henley William J. , Dunton Kenneth H. 
Published: October 2004

ABSTRACTLaminaria solidungula and L. saccharina inhabit the Beaufort Sea in the Alaskan High Arctic. Laminaria solidungula is an Arctic endemic, whereas L. saccharina extends from north temperate Pacific and Atlantic waters to the Arctic. Previous studies have shown that the two species have different seasonal timing of growth, but little comparative physiological information exists. As a first step in characterizing these two species from a mixed Arctic population, we measured variations in carbon, nitrogen, and photosynthetic pigment content in blade tissue from plants collected under the fast ice in April and during the open water Period in late July, Both species exhibited seasonal differences in many measured variables; seasonal differences in L. solidungula were most pronounced in growing basal blades. For example, the molar CIN ratio of basal blades averaged 11 in April and 21 in July for L. solidungula and 11.5 in April and 28 in July for L. saccharina. Basal and mature second blades differed in pigment content in April but not in July: chlorophyll a + c in L. solidungula basal and mature second blades averaged 19 and 27 nmol.cm−2 in April and 30 and 29 nmol. cm−2 in July, respectively. The corresponding values for L. saccharina were 17 and 29 nmol.cm−2 in April and 16 and 16 nmol.cm−2 in July (95% confidence intervals approximately 1–3 nmol. cm −2). Carotenoids exhibited similar patterns. Species differences in pigments, carbon, and nitrogen were minor and were probably effects rather than causes of the different seasonal patterns of growth and development. The primary difference between the two species may be the ability of L. solidungula to retain multiple metabolically active blades and to fuel areal growth with stored carbohydrates during winter near‐darkness, whereas L. saccharina growth is more closely tied to active photosynthesis in the growing basal blade. The cause of old blade retention in L. solidungula and the possibility of other physiological differences between the two species, including gametophytes, remain to be determined.
CHARACTERIZATION OF THE LIGHT‐HARVESTING COMPLEX OFGIRAUDYOPSIS STELLIFER(CHRYSOPHYCEAE) AND EFFECTS OF LIGHT STRESS1
Authors: Lichtlé Christiane , Arsalane Wafa , Duval Jean Claude , Passaquet Chantal 
Published: October 2004

ABSTRACTThe light‐harvesting complex (LHC) ofGiraudyopsis stelliferDangeard was isolated on a sucrose density gradient after digitonin treatment, and the pigment composition was analyzed by reverse‐phase high‐pressure liquid chromatography. The LHC is a chlorophyll (Chl) a/c/fucoxanthin/violaxanthin complex, depleted of β‐carotene, comparable to the LHC of Fucophyceae. The excitation transfer from Chlcand fucoxanthin to Chlais efficient in whole cells. Immunological reactions indicate a close relationship between Chrysophyceae and Fucophyceae. The immunocytochemical labeling confirms the lack of segregation of the LHC in the appressed membranes of the three associated thylakoids and its localization in the intrapyrenoid thylakoid. The violaxanthin‐antheraxanthin‐zeaxanthin cycle is operative in the cells and efficiently protects photosystem II reaction centers against photoinhibition.
CELL DIVISION IN THE DINOFLAGELLATE GAMBIERDISCUS TOXICUS IS PHASED TO THE DIURNAL CYCLE AND ACCOMPANIED BY ACTIVATION OF THE CELL CYCLE REGULATORY PROTEIN, CDC2 KINASE1
Authors: van Dolah Frances M. , Leighfield Tod A. , Sandel H. Daniel , Hsu Chuin Kang 
Published: October 2004

ABSTRACT The cell division cycle in several pelagic dinoflagellate species has been shown to be phased with the diurnal cycle, suggesting that their cell cycle may be regulated by a circadian clock. In this study, we examined the cell cycle of an epibenthic dinoflagellate, Gambierdiscus toxicus Adachi and Fukuyo (Dinophyceae), and found that cell division was similarly phased to the diurnal cycle. Cell division occurred during a 3‐h window beginning 6 h after the onset of the dark phase. Cell cycle progression in higher eukaryotes is regulated by a cell cycle regulatory protein complex consisting of cyclin and the cyclin‐dependent kinase CDC2. In this report, we identified a CDC2‐like kinase in G. toxicus that displays activity in vitro against a known substrate of CDC2 kinase, histone H1. As in higher eukaryotes, CDC2 kinase was expressed constitutively in G. toxicus throughout the cell cycle, but it was activated only late in the dark phase, concurrent with the presence of mitotic cells. These results indicate that cell division in G. toxicus is regulated by molecular controls similar to those found in higher eukaryotes.
PSEUDO‐NITZSCHIA PUNGENS AND P. MULTISERIES (BACILLARIOPHYCEAE): NOMENCLATURAL HISTORY, MORPHOLOGY, AND DISTRIBUTION1
Authors: Hasle Grethe Rytter 
Published: October 2004

ABSTRACTPseudo‐nitzschia pungens f: multiseries is raised in rank from form to species based on morphological, physiological, and genetic features. Distinctive details of the valve face striae, the valve mantle, and the girdle of P. pungens and P. multiseries are outlined. The nomenclatural history and the distribution of the two species and their relationship to other species of the genus are discussed.
CARBON AVAILABILITY AND THE PATTERN OF CYANOBACTERIAL DOMINANCE IN ENRICHED LOW‐CARBON LAKES1
Authors: Klemer Andrew R. , Hendzel Len L. , Findlay David L. , Hedin Randy A. , Mageau Michael T. , Konopka Allan 
Published: October 2004

ABSTRACT We hypothesize that the pattern of cyanobacterial dominance in experimentally enriched, low‐carbon lakes is related not only to the resultant N:P ratio but also to the availability of carbon for gas‐vesicle synthesis. We tested this hypothesis by determining the buoyancy responses of a highly gas‐vacuolate, N2‐fixing cyanobacterium to P enrichment with and without induced C limitation. Enrichment of samples of Aphanizomenon schindleri (Kling et al. 1994) from blooms in Lake 227 with combinations of C, N, and P produced rapid buoyancy reductions in P treatments, reductions that were reversed within a generation time in treatments that included C or C and N as well as P. These responses are the first of their kind to be observed in experiments with lake populations of cyano‐bacteria. The rapid buoyancy reductions were associated with polyphosphate accumulations in P‐treated A. schindleri. Differences in buoyancy status after one generation time were linked to differences in relative gas vacuolation between samples treated with P only and samples treated with C and N as well as P. These results may explain the relative success of different types of cyanobacteria in newly enriched, low‐carbon lakes. The availability of C for gasvesicle synthesis may determine whether a low N:P ratio induces N2 fixation by benthic or by planktonic cyanobacteria and whether a high NP ratio leads to dominance by non‐gas‐vacuolate or by highly gas‐vacuolate, non‐N2‐fixers.
INFLUENCE OF FLUCTUATING PHOSPHATE SUPPLY ON THE REGULATION OF PHOSPHATE UPTAKE BY THE BLUE‐GREEN ALGA ANACYSTZS NIDULANS1
Authors: Falkner Gernot , Wagner Ferdinand , Small John Victor , Falkner Renate 
Published: October 2004

ABSTRACT The blue‐green alga Anacystis nidulans Drouet (Synechococcus leopoliensis Raciborski) cultivated under phosphate‐limited conditions adopts a threshold value in the nanomolar range below which uptake ceases. In this study, we investigated the influence of phosphate pulses on the regulation of uptake behavior during reestablishment of the threshold value. Short‐term pulses had only a slight effect on uptake kinetics and, hence, on the threshold value, even if the population had been exposed several times to elevated concentrations above the steady‐state level in the growth medium. The threshold value was also practically insensitive to the amount of phosphate stored during these short‐term fluctuations. Long‐term phosphate pulses resulted in a transition to a metastable state that was characterized by a severalfold higher threshold value. This transition, apparently an adaptation to the transiently elevated phosphate concentrations, was further studied by following the influx of 32P‐phosphate at constant external concentrations and was shown to be complete after a period of 10–20 min. After adaptation to pulses, the uptake behavior followed a linear flow‐force relation over a wide range of external concentrations. This behavior was explained by the simultaneous operation of at least two uptake systems with different, but coordinated kinetic parameters. This linear flow‐force relation facilitated a direct determination of the threshold value from uptake measurements. For applicability in the field the force‐flow relation can be a diagnostic tool to assay for fluctuating phosphate and to establish threshold values below the normal measurable range.
SPECTRAL CHARACTERIZATION OF NEW CHLOROPHYLLCPIGMENTS ISOLATED FROMEMILIANIA HUXLEYI(PRYMNESIOPHYCEAE) BY HIGH‐PERFORMANCE LIQUID CHROMATOGRAPHY1
Authors: Garrido José L. , Zapata Manuel , Muñiz Susana 
Published: October 2004

ABSTRACTPigment extracts from the prymnesiophyteEmiliania huxleyi (Lohm.) Hay & Mohler (CCMP 370) were analyzed using a new chromatographic method based on the use of polymeric octadecylsilica columns, which split both the chlorophyllc3peak and phytol‐substituted chlorophyllc‐like peak into two fractions. The pigments corresponding to each of these fractions were isolated. The spectra and chromatographic behavior suggest that chlorophyll c3fromE. huxleyiis a mixture of two different compounds whereas the splitting of the phytol‐substituted c‐like pigment could be the result of the equilibrium of two forms showing the same absorption spectrum. The method allowed, as well, the detection of magnesium 3,8‐divinylpheoporphy‐rin a, monomethyl ester in the prymnesiophytesE. huxleyi (CCMP 370) andPrymnesium parvumCarter (CCMP 708) and the chrysophytePelagococcus subviridisNorris (CCMP 1429).
COLINEARITY OF CHLOROPLAST GENOMES IN DIVERGENT ECOTYYES OF THE MARINE DIATOM SKELETONEMA COSTATUM (BACILLARIOPHYTA)1
Authors: Stabile Joseph E. , Gallagher Jane C. , Wurtzel Eleanore T. 
Published: October 2004

ABSTRACT The chloroplast genomes of three isolates of the marine diatom Skeletonema costatum (Grev.) Cleve were mapped and found to be 131 ± 2 kb with inverted repeats (IRs) of approximately 20 kb. In contrast to higher plants, the psbA gene mapped to the IR, and rbcS mapped to the same fragment as the rbcL gene in the large single‐copy region. The maps of the three isolates were colinear and revealed as many as 20 site mutations out of a total of 47 sites. The number of site mutations among isolates was consistent with previous data on their genetic diversity and physiology. Comparisons of gene order among our maps and those of three other diatom species showed that closely related genera retained similar gene orders but that more distantly related taxa exhibited extensive rearrangements. We conclude that simple restriction fragment analysis of chloroplast DNA is useful in comparative studies of diatom populations and species but that other analytical methods are more appropriate for phylogenetic studies at higher levels.
INHERITANCE AND MEIOTIC ELIMINATION OF A VIRUS GENOME IN THE HOST ECTOCARPUS SZLZCULOSUS (PHAEOPHYCEAE)1
Authors: Bräutigam Martin , Klein Michael , Knippers Rolf , Müller Dieter G. 
Published: October 2004

ABSTRACT The marine brown alga Ectocarpus siliculosus (Dillwyn) Lyngbye is frequently infected by a latent DNA virus that multiplies in modified sporangia and gametangia of the host. We describe a polymerase chain reaction (PCR) procedure for the amplification and detection of viral DNA in Ectocarpus. PCR analysis of parents and progeny plants confirmed that virus DNA passes through meiosis like a Mendelian trait. An infected sporophyte produced equal numbers of gametophytes with and without the viral genome. Thus, meiosis in sexual populations of the host acts as a mechanism for the creation of virus‐free progeny.
SPATIAL DYNAMICS OF A HIMANTHALIA ELONGATA (FUCALES, PHAEOPHYTA) POPULATION
Authors: Creed Joel C. 
Published: October 2004

ABSTRACT In dense monospecific stands of plants intraspecific competition usually results in self‐thinning, the concurrent increase in biomass and decrease in density over time. Self‐thinning may also result in a change in the spatial pattern of individuals, but so far the spatial dynamics of marine plants has not been investigated. The brown alga Himanthalia elongata (L.) S. F. Gray forms dense monospecific stands on many northern temperate rocky shores, and various attributes (including its simple form) facilitated the study of the spatial dynamics of this species. The spatial pattern of settling zygotes was examined in the laboratory. In the absence of water movement, substratum heterogeneity, and a point source, zygotes usually settled in clumps rather than randomly. Within the clumps zygotes appeared to be regularly distributed at a scale similar to the size of the zygotes themselves. Furthermore, the clumps themselves seemed to be regularly distributed. On the shore, well‐established stands of “button‐stage” Himanthalia populations were examined during a period of extensive growth and self‐thinning. Individual plants were initially highly regular in spatial pattern but became less so over time. The pattern of plants dying during self‐thinning was also highly regular and probably reflected existing spatial regularity. However, using a hypothesis of mortality as a random event, I found that smaller plants had a less than average survival potential, while larger plants had a greater than average chance. A consideration of the spatial pattern of plants alive at the end of the study revealed regularity at a scale of 2–7 mm but a random spatial pattern at larger scales, which might indicate a small sphere of influence of competing individuals. The best predictor of mean nearest neighbor distances in the populations was mean plant diameter.
CARBONIC ANHYDRASE ACTIVITY IN THE BLOOM‐FORMING DINOFLAGELLATE PERIDINIUM GATUNENSE
Authors: Berman‐Frank Ilana , Kaplan Aaron , Zohary Tamar , Dubinsky Zvy 
Published: October 2004

ABSTRACT The response of carbonic anhydrase (CA) activity in Peridinium gatunense Nygaard, the natural bloom‐forming dinoflagellate in Lake Kinneret, to diel and seasonal variations in environmental conditions was characterized under controlled laboratory experiments. Simulated diel cycles demonstrated large changes in the ambient concentration of dissolved CO2 and parallel changes in CA activity. The CA activity depended on the total concentrations of inorganic carbon (C1) and in particular on the dissolved CO2. Lowering the C1concentrations resulted in a large increase in CA activity within several hours. Light and photosynthesis were both required for the induction of CA activity. Under CO2 ‐limited conditions, the dependence of the photosynthetic rate on CA (estimated from the ratio of photosynthetic rates in the presence or absence of CA inhibitors) was greater in P. gatunense than in other eukaryotic microalgae. This points to the ecological significance of CA in photosynthetic carbon uptake mechanisms of a large, dominant alga in a natural ecosystem.