bluuebunny/crossref_metadata_2025_split huggingface dataset:
POTENTIAL TOLERANCE MECHANISMS OF PROROCENTRUM MICANS (DINOPHYCEAE) TO SUBLETHAL LEVELS OF COPPER1
Authors: Lage Olga M. , Parente Ana M. , Vasconcelos M. Teresa S. D. , Gomes Carlos A. R. , Salema Roberto 
Published: October 2004

ABSTRACTWe investigated how Prorocentrum micans Ehrenberg, a planktonic dinoflagellate common in Portuguese coastal waters, is able to tolerate and recover from sublethal concentrations of copper(II). The experimental design simulated events in inshore waters, where P. micans is subjected to high levels of pollutants, including copper. Decrease in growth rate, induction of a growth lag phase, temporary loss of motility, and potassium leakage were the effects induced in P. micans cultures by 90 nM labile copper. A 10–20‐fold increase in cellular copper concentration was observed in toxicity experiments. Copper efflux (representing a 50% decrease in cellular metal content) was a short‐term tolerance mechanism. A 25‐kDa protein was detected after only 3 h of exposure to copper, but there was no evidence of phytochelatin synthesis. Ultracytochemical labeling of metals with the sulfide‐silver procedure showed that copper was associated with the thecal plates, starch grains, and, to a lesser extent, lipid droplets. High values affixation capacities and average conditional stability constants for copper binding by starch, amylopectin, and cellulose support the location of copper in thecal plates and starch grains. We conclude that P. micans responds rapidly to copper toxicity and has two tolerance mechanisms for copper: copper efflux and sequestration in polymeric substances.
ASSESSING THE LIMITS OF RANDOM AMPLIFIED POLYMORPHIC DNAs (RAPDs) IN SEAWEED BIOGEOGRAPHY1
Authors: van Oppen Madeleine J. H. , Klerk Hans , de Graaf Martin , Stam Wytze T. , Olsenz Jeanine L. 
Published: October 2004

ABSTRACTAs judged by comparison with other molecular data sets, random amplified polymorphic DNA (RAPD) data are robust in identifying large‐scale biogeographic populations that range from hundreds to thousands of kilometers apart. As the geographical scale is shifted downward, however, RAPD data often fail. This is because RAPD data are inherently “noisy” as a result of technical artifacts and reproducibility problems associated with non‐independence of bands, “missing” bands, and the presence of de novo bands, all of which contribute to scoring errors in the data set. To estimate the contribution of these error factors in algal phylogeographic studies, segregation of RAPD bands in tetrasphorophytic and gametophytic parents, their natural and synthetic offspring, and self‐cycled tetrasporophytes were compared in Lophocladia trichoclados (Mertens in C. Agardh) Schmitz and to a limited extent in Digenea simplex (Wulfen) C. Agardh. Wide‐ranging biogeographic populations of D. simplex were compared as were mixed populations of tetrasporophytes and gametophytes. Results show that nested priming can lead to some nonindependence of bands but that this probably does not significantly contribute to scoring error. Southern analysis using individual RAPD bands as probes revealed that up to 16% of visually nondetectable bands are actually present but that the random distribution of the error contributes uniformly across the data set. Non‐parental (de novo in offspring) and parental (not present in offspring) bands may contribute substantially to the scoring error in tetrasporophytes, gametophytes, and self‐cycled tetrasporophytes. The presence of tetrasporophytes and gametophytes in a sample is not important in large‐scale phylogeographic studies but does affect within‐clade variation at smaller scales. We conclude that the overall level of error remains roughly constant at probably between 5 and 10%, which is not a problem at large biogeographic scales where the phylogenetic signal is strong. Finally, some unexpectedly large abberations in RAPD banding patterns among life stages in L. trichoclados were observed that cannot be explained by methodological artifacts alone due to comparisons with synthetic offspring controls. The possibility that carpospore amplification may not always involve a simple mitotic process is discussed.
RECENT RADIATION OF THE PALMARIACEAE (RHODOPHYTA)1
Authors: Lindstrom Sandra C. , Olsen Jeanine L. , Stam Wytze T. 
Published: October 2004

ABSTRACTMolecular phylogenetic studies on the evolution of the red algae indicate that this ancient division has many lineages that have recently undergone radiations. One such example is the cold–temperate family Palmariaceae. In this study, sequences from the ribosomal DNA internal transcribed spacer regions were compared among ten species in the Palmariaceae from both Atlantic and Pacific sites, Phylogenetic analyses of sequence data, in whichRhodophysema georgiiBatters was used as outgroup and root, indicate a radiation into four clades, three of which contain species of“Palmaria”and the fourth species ofHalosaccion. Palmaria palmata(L.) Kuntze, the type and only North Atlantic species in the genus, stands apart from all remaining species in the family and terminates the most basal branch in the rooted tree. The three more derived clades have radiated mainly in the North Pacific. Southern OceanPalmariaand North AtlanticDevaleraeaare hypothesized to have invaded from separate but closely related North Pacific ancestors. The ease with which sequences could be aligned combined with an unsaturated transition: transversion ratio and modest divergence involving predominantly point mutations suggests that the initial radiation is relatively recent (late Miocene–Pliocene) and that theDevaleraea–Palmariaclade is even more recent (late Pliocene–Pleistocene).
BACTERIA THAT INDUCE MORPHOGENESIS IN ULVA PERTUSA (CHLOROPHYTA) GROWN UNDER AXENIC CONDITIONS1
Authors: Nakanishi Koichi , Nishijima Miyuki , Nishimura Masamichi , Kuwano Kazuyoshi , Saga Naotsune 
Published: October 2004

ABSTRACTMarine foliaceous green macroalgae such as Ulva lose their typical morphology when cultured aseptically in defined synthetic media. However, after reinfection by certain marine bacteria (isolated from unialgal cultures of Ulva pertusa Kjellman), the organisms regain their typical foliaceous or tubular morphology. To investigate the morphogenesis (MG) induced in U. pertusa by bacteria, we isolated and identified bacteria with MG activity on U. pertusa and studied the distribution of such bacteria in seawater and on various marine macroalgae. We isolated 1555 bacterial strains from 18 species of marine macroalgae (six Chlorophyta, five Phaeophyta, and seven Rhodophyta), from seawater and from sediment collected at the beach at Omaezaki, Shizuoka Prefecture; Japan. Of these, 676 bacterial strains (43.5%) showed MG activity. They were classified into six bacterial groups, Flavobacterium, Vibrio, Pseudomonas, Deleya, Escherichia, and gram‐positive cocci. These bacteria were ubiquitous among the samples and were not specific to U. pertusa. Several plant growth regulators had no MG activity. Filter‐sterilized supernatants of culture media of MG‐active bacteria strains did not induce MG. Cocultivation of Ulva with active bacterial strains is so far the only way to induce the MG effect, which suggests that for MG direct contact between Ulva and the bacterial strain is necessary.
A NEW, ARTIFICIAL SEA WATER THAT FACILITATES GROWTH OF LARGE NUMBERS OF CELLS OFACETABULARIA ACETABULUM(CHLOROPHYTA) AND REDUCES THE LABOR INHERENT IN CELL CULTURE1
Authors: Hunt Brenda E. , Mandoli Dina F. 
Published: October 2004

ABSTRACTWe designed a new, artificial seawater (Ace 25) in order to grow bulk cultures ofAcetabularia acetabulum(L.) Silva with a minimum of labor. To this end, we modified the traditional recipe for cell growth (Müller's medium as modified by Schweiger et al.) We eliminated five of the inorganic chemicals and determined the optimum concentration for 16 of the remaining 18 inorganic chemicals from modified Müller's seawater. Ace 25 enables growth ofA. acetabulumfrom the beginning of the juvenile phase through gametangial formation in 11 weeks at high cell densities without medium replenishment. This represents a 98% reduction in the seawater volume required to mature each cell, a 30–40% reduction of the duration of the life cycle, an estimated 80% reduction in labor, and a 50–95% reduction in the space required for culturingA. acetabulumas compared with traditional procedures. These improvements may facilitate studies that require large numbers of cells such as population studies, genetics, and biochemistry, contribute to understanding the nutritional requirements of marine algae, and extend the use of this cell to those who lack the space or manpower to grow the cells in the traditional manner.
A METHOD FOR EXTRACTION OF HIGH MOLECULAR WEIGHT DNA FROM THE MACROALGA PORPHYRA YEZOENSIS (RHODOPHYTA)1,2
Authors: Kitade Yukihiro , Yamazaki Satoru , Saga Naotsune 
Published: October 2004

ABSTRACTWe developed a method for extraction of DNA from the red alga Porphyra yezoensis Ueda. The method consists of three preparation steps that include CsCl‐gradient ultracentrifugation, cetyl trimethyl ammonium bromide treatment, and a final RNase step. The amount of DNA extracted from 1.5 g of starting material averaged 17.7 μg. The resulting DNA had a high molecular weight, was 25‐166 kb in length, was digested with five common restriction enzymes, and showed no nuclease activity. It was of sufficient quality for construction of genomic libraries.
GROWTH AND ORGANIC OSMOLYTES OF GEOGRAPHICALLY DIFFERENT ISOLATES OF MICROCOLEUS CHTHONOPLASTES (CYANOBACTERIA) FROM BENTHIC MICROBIAL MATS:RESPONSE TO SALINITY CHANGE1
Authors: Karsten Ulf 
Published: October 2004

ABSTRACTThe comparative growth and osmotic acclimation often culture strains of the marine benthic cyanobacterium Microcoleus chthonoplastes Thuret isolated from microbial mats in Germany, Spain, Egypt, the United States, Mexico, Chile, and Australia were investigated in salinities ranging from freshwater to twice seawater. All isolates showed a broad growth versus salinity response consistent with the dominance of this species in intertidal and hypersaline microbial communities. Growth optima, salinity preferences, and maximum growth rates differed for each isolate and could be related to the habitat from which they were isolated. This is most obvious when comparing strains from brackish habitats with those from a hypersaline lake. While the former isolates exhibited sharply pronounced growth optima under hyposaline conditions, cultures from the hypersaline environment grew best in salinity more than double seawater. The major low‐molecular weight organic compounds present in all M. chthonoplastes strains were the carbohydrates glycosylglycerol and trehalose. This was proven by using 13C‐nuclear magnetic resonance spectroscopy. Glycosylglycerol was synthesized and accumulated with increasing salinities, indicating its role as an osmolyte. In contrast, trehalose was present in relatively high concentrations under hyposaline conditions only. Differences in the patterns of growth versus salinity, as well as in those of osmotic acclimation among the M. chthonoplastes isolates, point to the development of different physiological ecotypes within the species.
THE EFFECT OF PHOSPHATE STATUS ON THE KINETICS OF CYANOPHAGE INFECTION IN THE OCEANIC CYANOBACTERIUM SYNECHOCOCCUS SP. WH78031
Authors: Wilson William H. , Carr Noel G. , Mann Nicholas H. 
Published: October 2004

ABSTRACTPhycoerythrin‐containing Synechococcus species are considered to be major primary producers in nutrient‐limited gyres of subtropical and tropical oceanic provinces, and the cyanophages that infect them are thought to influence marine biogeochemical cycles. This study begins an examination of the effects of nutrient limitation on the dynamics of cyanophage/Synechococcus interactions in oligotrophic environments by analyzing the infection kinetics of cyanophage strain S‐PM2 (Cyanomyoviridae isolated from coastal water off Plymouth, UK) propagated on Synechococcus sp. WH7803 grown in either phosphate‐deplete or phosphate‐replete conditions. When the growth of Synechococcus sp. WH7803 in phosphate‐deplete medium was followed after infection with cyanophage, an 18‐h delay in cell lysis was observed when compared to a phosphate‐replete control. Synechococcus sp. WH7803 cultures grown at two different rates (in the same nutritional conditions) both lysed 24 h postinfection, ruling out growth rate itself as a factor in the delay of cell lysis. One‐step growth kinetics of S‐PM2 propagated on host Synechococcus sp. WH7803, grown in phosphate‐deplete and‐replete media, revealed an apparent 80% decrease in burst size in phosphate‐deplete growth conditions, but phage adsorption kinetics ofS‐PM2 under these conditions showed no differences. These results suggested that the cyanophages established lysogeny in response to phosphate‐deplete growth of host cells. This suggestion was supported by comparison of the proportion of infected cells that lysed under phosphate‐replete and‐deplete conditions, which revealed that only 9.3% of phosphate‐deplete infected cells lysed in contrast to 100% of infected phosphate‐replete cells. Further studies with two independent cyanophage strains also revealed that only approximately 10% of infected phosphate‐deplete host cells released progeny cyanophages. These data strongly support the concept that the phosphate status of the Synechococcus cell will have a profound effect on the eventual outcome of phage‐host interactions and will therefore exert a similarly extensive effect on the dynamics of carbon flow in the marine environment.
ECOTYPIC VARIATION IN CYSTOCLONIUM PURPUREUM (RHODOPHYTA) SYNCHRONIZES LIFE HISTORY EVENTS IN DIFFERENT REGIONS1
Authors: Molenaar Frieda J. , Breeman Anneke M. , Venekamp Loes A. H. 
Published: October 2004

ABSTRACTTemperature and daylength responses were determined in culture for isolates of the red alga Cystoclonium purpureum (Hudson) Batters from Nova Scotia (NS, Canada), Helgoland (HE, Germany), and Roscoff (RO, France). Most isolates survived temperatures of –1.5°/–2° to 23°C, whereas 25°C was lethal. Only the RO‐gametophytes died at 23°C. Optimal growth conditions were 10°–20°C in both long and short days for the NS isolates and 8°–15°C and 8°–18°C at daylengths of >12 h for the RO and HE isolates, respectively. Tetrasporophytes and gametophytes of the NS isolate reproduced at 10°–20°C in long and short days within 5 months. At lower temperatures reproduction was limited or slow. The European isolates formed tetrasporangia at 10°–20°C (HE) or 5°–l8°C(RO), spermatangia at 5°–15°C (HE) or 5°–20°C (RO), and carpospores at 5°–15°C(HE) or 10°–15°C (RO). Short days either blocked or delayed reproduction of the European isolates.The phenology of C. purpureum was studied at Helgoland and Roscoff, where similar seasonal patterns were observed. In early spring, growth was rapid and plants started to form reproductive structures. In summer, tetra‐and carpospores were shed followed by degeneration of the upright axes while branched holdfasts persisted. New upright axes and juvenile plants were formed in autumn, but these remained small during the winter months. Published data indicate that the seasonal pattern at Nova Scotia is similar, although the onset of growth and reproduction is delayed until the end of spring. These observations correspond well with the results of the experiments.The life history of C. purpureum is regulated by temperature and daylength. In the eastern Atlantic, the limiting effect of short days confines growth and reproduction to spring and summer. In the western Atlantic, low winter temperatures alone bring about the same seasonal pattern. After plants have reproduced, uprights degenerate in spite of continuing favorable conditions.
RESTING CYST FORMATION OFEUTREPTIELLA GYMNASTICA(EUGLENOPHYCEAE) IN THE NORTHERN COASTAL BALTIC SEA1
Authors: Olli Kalle 
Published: October 2004

ABSTRACTResting cyst formation ofEutreptiella gymnasticaThrondsen was observed during a mesocosm experiment, where nutrient enrichment had induced almost a unialgal bloom. Cells and resting cysts ofE. gymnasticawere examined in scanning (SEM) and transmission electron microscopy (TEM) and light microscopy. Mature cysts were spherical, with a smooth thick mucilaginous cover that appeared layered when observed with the TEM. Intermediate forms were spherical and lacking flagella and a mucilaginous cover; the euglenoid pellicular striation and canal opening were easily visible. The volume of these intermediate spherical cells and mature cysts was estimated to have increased threefold compared to flagellated cells and contained many paramylon grains. When the cells were grazed by zooplankton, the paramylon grains passed the gut intact and were packed into fecal pellets. Intact undigested paramylon grains were observed in SEM after the breaking up of the pellets.
DESMID‐BACTERIAL ASSOCIATIONS IN SPHAGNUM‐DOMINATED WISCONSIN PEATLANDS1
Authors: Fisher Madeline M. , Wilcox Lee W. 
Published: October 2004

ABSTRACTIn a survey employing epifluorescence microscopy with the DNA fluorochrome DAPI, associations between bacteria and filamentous desmids were found to be commonplace in acidic, Sphagnum‐dominated Wisconsin peat‐lands. Bacteria were associated with all genera of filamentous desmids encountered including Desmidium, Hyalotheca, Onychonema, Spondylosium, and Teilingia. Although only associations involving filamentous desmids having mucilaginous sheaths are illustrated here, bacteria were also noted on taxa lacking sheaths as well as some unicellular forms. Bacteria on Desmidium majus Lagerheim, D. grevillii (Kütz.) De Bary, and Hyalotheca dissiliens (Smith) Bréb. ex Ralfs tended to be concentrated in small pockets in the sheath material located near the isthmus and in the region between adjacent cells in the filament, whereas those associated with Spondylosium pulchrum (Bail.) Archer were more evenly distributed throughout the sheath. Most bacteria were rodshaped. Those associated with S. pulchrum, D. grevillii, and D. majus ranged from 1.1 to 11.2 μm in length. Bacteria within the sheaths of H. dissiliens and D. grevillii were Gram‐negative. A second morphologically distinct population of bacteria was found at the sheath margin in D. majus and D. grevillii. Field collections containing filamentous desmids were examined with scanning electron microscopy and bacteria associated with Desmidium majus were investigated with transmission electron microscopy.
CHANGES IN PHOTOSYNTHESIS IN RESPONSE TO COMBINED IRRADIANCE AND TEMPERATURE STRESS IN CYANOBACTERIAL SURFACE WATERBLOOMS1
Authors: Ibelings Bas W. 
Published: October 2004

ABSTRACTBuoyant cyanobacteria, previously mixed throughout the water column, float to the lake surface and form a surface waterbloom when mixing subsides. At the surface, the cells are exposed to full sunlight, and this abrupt change in photon irradiance may induce photoinhibition; at the same time, temperature rises as well. This study investigated the damaging effects of this increase in temperature as well as the ecologically more relevant combination of both an increased temperature and a high photon irradiance. Analysis of surface blooms with oxygen microelectrodes showed that integrated oxygen contents that are dependent on the balance of photosynthetic oxygen evolution and respiratory oxygen uptake decreased when temperature was raised above the lake temperature. Gross rates of photosynthesis were unaffected by temperatures up to of 35°C; hence, a moderate increase in temperature mainly stimulated oxygen uptake. Preincubation of cells of the cyanobacterium Anabaena flos‐aquae (Lyngb.) de Brébisson at temperatures up to 35°C did not affect the subsequent measurement of rates of net photosynthesis. Another 5°C rise in temperature severely damaged the photosynthetic apparatus. Failure to restore net rates of photosynthesis was coupled to a strong quenching of the ratio of variable to maximum fluorescence, Fv/Fm, that was the result of a rise in Fo. A combination of high temperature and high photon irradiance was more damaging than high temperature alone. In contrast, low photon irradiances offered substantial protection against heat injury of the photosynthetic apparatus. I conclude from this study that because cyanobacteria usually are acclimated to low average irradiance prior to bloom formation, there is a reasonable risk of chronic photoinhibition. The increase in temperature will enhance the photodamage of cells in the top layer of the bloom. Low photon irradiances in subsurface layers will offer protection against heat injury. If the high temperatures extend to the deepest, dark layers of the bloom, damage in those layers is likely to occur.
AKINETE DIFFERENTIATION IN ANABAENA CIRCINALIS (CYANOPHYTA)1
Authors: van Dok Wendy , Hart Barry T. 
Published: October 2004

ABSTRACTThree lines of evidence established conclusively that phosphorus limitation triggered akinetes to differentiate in Anabaena circinalis Rabenhorst. First, akinetes differentiated when phosphorus was limited, but not when nitrogen, inorganic carbon, iron, trace elements, or light were limited, or when dissolved oxygen concentration was increased. In the phosphorus limitation experiment, akinetes appeared first in the 0 mg P‐L−1 cultures, and the higher the initial concentration of phosphorus was, the longer it took for akinetes to differentiate. Second, akinete differentiation commenced when Qp fell to the same critical concentration in all cultures. The critical Qp for akinete differentiation in A. circinalis was 0.3‐0.45 pg P·cell−1, and there was no significant difference between cultures grown with 0.6, 0.2, 0.06, or 0 mg P · L−1 (F= 5.48, of = 3, P > 0.05). Similarly, there were no significant differences between P cultures in internal cellular soluble reactive phosphorus (SRP) concentration (F= 0.63, df = 3, P > 0.05) or external SRP per cell in the medium (F= 5.16, df= 3, P > 0.05) when akinete differentiation commenced. Both were between 0.01 and 0.07 pg SRP‐cell−1. A thorough literature search indicates that this information has not been reported previously. The third line of evidence came from electron micrographs, which illustrated that polyphosphate was present in trichomes prior to akinete differentiation but was absent in trichomes with akinetes indicating that phosphorus reserves were depleted when akinetes differentiated. Lipid globules (carbon reserve) and cyanophycin granules (nitrogen reserve) increased in number in trichomes with akinetes, compared to trichomes without akinetes. Thus, the ratio of internal P:C:N was different in trichomes with akinetes compared to trichomes without akinetes and may be important in activating akinete‐differentiating genes.