bluuebunny/crossref_metadata_2025 huggingface dataset:
RECENT RADIATION OF THE PALMARIACEAE (RHODOPHYTA)1
Authors: Lindstrom Sandra C. , Olsen Jeanine L. , Stam Wytze T.
Published: October 2004

Molecular 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

Marine 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

We 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

We 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

The 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

Phycoerythrin‐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

Temperature 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

Resting 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

In 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

Buoyant 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

Three 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.
WAVELENGTH DEPENDENCY OF THE MAXIMUM QUANTUM YIELD OF CARBON FIXATION FOR TWO RED TIDE DINOFLAGELLATES, HETEROCAPSA PYGMAEA AND PROROCENTRUM MINIMUM (PYRROPHYTA): IMPLICATIONS FOR MEASURING PHOTOSYNTHETIC RATES1
Authors: Schofield Oscar , Prézelin Barbara , Johnsen Geir
Published: October 2004

The influence of photoadaptive state on the spectral dependency of the maximum quantum yield for carbon fixation was determined for two red tide dinoflagellates, Heterocapsa pygmaea Loeblich, Schmidt, et Sherley and Prorocentrum minimum Pavillard. Cultures were acclimated to green, blue, red, and white light. The spectral dependency in the light‐limited slope of the photosynthesis–irradiance curves (α) was measured with carbon action spectra that, when divided by the spectrally weighted absorption coefficient, provided estimates of the maximum quantum yield (φmax) for carbon fixation. Values of φmax varied with wavelength within each culture condition as well as between different culture conditions. The degree to which the spectral dependency in φmax was influenced by the presence of photoprotective carotenoids and/or energy imbalances between photosystems I and II was assessed for both dinoflagellates. The impact of photoprotective pigmentation on the spectral dependency of φmax was most significant for cells grown under high light conditions reflecting the enrichment of diadinoxanthin. Energy imbalances between the photosystems was assessed by quantifying enhancement effects on spectral φmax in the presence of background illumination. Under our experimental conditions, enhancement effects on carbon action spectra were evident for H. pygmaea under nearly all growth conditions but were not detectable for P. minimum under any growth condition. We hypothesize that sensitivity to enhancement effects reflected differences in the structure of the photosynthetic machinery of these two peridinin‐containing dinoflagellates. While measurements of φmax are sensitive to the color of the light within an incubator, the relative impact on the spectral dependency of a was less than the wavelength dependency associated with the cellular absorption properties. Finally we used our data to validate an approach proposed by others to aid in the correction of photosynthetic measurements where the in situ spectral light field cannot be easily mimicked. The average error using this approach was 8%, which was significantly less than the error associated with ignoring the spectral dependency in α.
INFLUENCE OF CELL WALL COMPOSITION ON THE RESISTANCE OF TWO CHLORELLA SPECIES (CHLOROPHYTA) TO DETERGENTS1
Authors: Corre Gwenael , Templier Joëlle , Largeau Claude , Rousseau Bernard , Berkaloff Claire
Published: October 2004

The influence of dodecylbenzene sulfonate (DBS) and Triton X‐100 (TX‐100) was examined on two species of Chlorella exhibiting conspicuous differences in cell wall composition. Chlorella emersonii has both a classical polysaccharidic wall and a thin trilaminar outer wall (TLS) composed of nonhydrolyzable macromolecules. Chlorella vulgaris lacks a TLS. Photosynthetic capacity was measured following short exposures (1 h) of the algae at different physiological stages to high DBS and TX‐100 concentrations, up to 1 g·L−1. Comparisons with untreated controls indicated that 1) the presence of a TLS in C. emersonii was associated with a very high resistance to the anionic (DBS) and nonionic (TX‐100) detergents at all growth stages, and net photosynthesis was not significantly affected in that species, 2) a high toxicity, particularly pronounced with TX‐100, was observed for actively growing cells of the TLS‐devoid species, C. vulgaris, and 3) aging exerted a protective influence, especially efficient against DBS, on the latter species. Additional observations, including fluorescence spectra and high‐performance liquid chromatography pigment analyses, were conducted following short exposures of actively growing cells. Fluorescence emission spectra revealed that the chlorophyll a‐protein complexes in thylakoid membranes were not substantially affected by DBS and TX‐100, even in the case of C. vulgaris. In sharp contrast, fluorescence excitation spectra on the latter species showed 1) that excitation transfer from antenna pigments to chlorophyll a in reaction centers was substantially altered with both detergents and 2) that the two detergents affected different parts of the photosynthetic system of the TLS‐devoid species. Analyses of C. vulgaris extracts indicated significant decreases in pigment content following exposure to DBS and, to a lesser extent, to TX‐100. Longer exposure experiments (1 day) were conducted with actively growing algae. The TLS‐containing species still showed a very high resistance and no important changes in photosynthetic capacity compared to cells exposed for 1 h. For the sensitive TLS‐devoid species, the detrimental influence of TX‐100, already very high after 1 h, was not increased. DBS toxicity was markedly increased and may reflect a lower uptake rate of DBS by C. vulgaris.

Taken together, these observations confirm the important protective role of TLS against detergents. They also provide information on the factors controlling detergent toxicity in the sensitive, TLS‐devoid species and on the different modes of action of DBS and TX‐100 on its photosynthetic system. Such large differences in microalgal sensitivity to detergents, related to TLS occurrence, should have important consequences for the selection of suitable species in toxicity tests.
EVIDENCE THAT MICROCYSTIN IS A THIO‐TEMPLATE PRODUCT1
Authors: Arment Anthony R. , Carmichael Wayne W.
Published: October 2004

The hepatotoxic cyclic heptapeptide toxins of cyanobacteria, collectively termed microcystins, are potent inhibitors of protein phosphatases PP1 and PP2A. The structure of microcystins resembles small, cyclic peptide secondary metabolites from fungi and eubacteria. Many of these metabolites are manufactured via a nonribosomal thio‐template mechanism. We submit evidence that microcystin is synthesized by a similar mechanism. The organism used in this study was Microcystis aeruginosa PCC7820.

Using the traditional ATP‐32PPi exchange assay for thio‐template activity, we found activity in the presence of the substrate d‐amino acids occurring in microcystin. Thio‐template mechanisms are known to be unaffected by protein synthesis inhibitors such as chloramphenicol. We subjected cultures in exponential and stationary growth to chloramphenicol and monitored culture health versus toxicity. Although the health of the treated cultures declined, the toxicity of the remaining cells increased. We developed an in vitro assay to measure microcystin synthesis in cell lysates in the presence of chloramphenicol. By supplementing the lysates with ATP and the substrate amino acids present in microcystin, we detected a fourfold increase in total microcystins over the course of 20 min.
FATTY ACID AND LIPID COMPOSITION OF THE ACIDOPHILIC GREEN ALGA CHLAMYDOMONAS SP.1
Authors: Tatsuzawa Hidetaka , Takizawa Etsuko , Wada Masayuki , Yamamoto Yoko
Published: October 2004

The lipid and fatty acid compositions of Chlamydomonas sp. isolated from a volcanic acidic lake and C. reinhardtii were compared, and the effects of pH of the medium on lipid and fatty acid components of Chlamydomonas sp. were studied. The fatty acids in polar lipids from Chlamydomonas sp. were more saturated than those of C. reinhardtii. The relative percentage of triacylglycerol to the total lipid content in Chlamydomonas sp. grown in medium at pH 1 was higher than that in other cells grown at higher pH. A probable explanation might be that Chlamydomonas sp. has two low pH adaptation mechanisms. One mechanism is the saturation of fatty acids in membrane lipids to decrease membrane lipid fluidity, and the other is the accumulation of triacylglycerol, as a storage lipid, to prevent the osmotic imbalance caused by high concentrations of H2SO4.
IMMUNOLOGICAL IDENTIFICATION OF THE ALTERNATIVE OXIDASE IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1
Authors: Derzaph Tina L. M. , Weger Harold G.
Published: October 2004

Using a monoclonal antibody to the alternative oxidase from voodoo lily, we provide evidence that the green alga Chlamydomonas reinhardtii Dang, possesses a protein that is immunologically related to the higher plant alternative oxidase. Mitochondria were isolated from a cell wall‐less mutant strain (CW‐15), and the presence of cyanide‐resistant oxygen consumption was confirmed in these mitochondria. The voodoo lily antibody was used as a probe for immunoblotting of sodium dodecyl sulphate‐polyacrylamide gel electrophoresis gels of mitochondrial proteins of C. reinhardtii. The antibody reacted with a protein from C. reinhardtii with the same molecular mass (36 kDa) as the alternative oxidase from voodoo lily and tobacco mitochondria. These results suggest that cyanide‐resistant respiration in C. reinhardtii is mediated by a higher plant‐type alternative oxidase.
IMMUNOLOCALIZATION OF NITRATE REDUCTASE IN THE MARINE DINOFLAGELLATE GONYAULAX POLYEDRA (PYRROPHYTA)1
Authors: Fritz Lawrence , Stringher Claudia Gadni , Colepicolo Pio
Published: October 2004

A polyclonal antibody, raised against nitrate reductase (NR) purified from the photosynthetic dinoflagellate Gonyaulax polyedra Stein, was used as a probe in immunogold‐labeling experiments on thin sections prepared from cells harvested both during day and night phases. Previous experiments have shown that both NR activity and the amount of immunoreactive NR in cell extracts is greater when day‐phase cells are examined, and this property was exploited as an internal control for the cytochemical labeling. We observed that in day‐phase cells, chloroplasts contained approximately three times more gold particles than night‐phase cells (highly significant difference; P < 0.0001), whereas cytoplasmic labeling levels remained relatively level between day and night. We conclude from the diurnal difference in labeling that our antibody faithfully reflects the distribution of NR in Gonyaulax cells. Thus, as in to some other higher plants and green algae, Gonyaulax compartmentalizes active NR in its chloroplasts.
IDENTIFICATION OF CULTURED PSEUDO‐NITZSCHIA (BACILLARIOPHYCEAE) USING SPECIES‐SPECIFIC LSU rRNA‐TARGETED FLUORESCENT PROBES1
Authors: Miller Peter E. , Scholin Christopher A.
Published: October 2004

Some, but not all, marine pennate diatoms of the genus Pseudo‐nitzschia H. Peragallo are associated with the production of domoic acid, a naturally occurring amino acid responsible for amnesic shellfish poisoning. Distinguishing between potentially toxic and nontoxic representatives of this genus is time‐consuming and difficult because it demands scanning electron microscopy of cleaned frustules. The objective of this work is to speed and ease identification of these organisms by using whole‐cell (in situ) hybridization and species‐specific large‐subunit ribosomal RNA (LSU rRNA)‐targeted oligonucleotide probes. Toward that end, cultures of P. australis Frenguelli, P. pungens (Grunow) Hasle, P. multiseries (Hasle) Hasle, P. fraudulenta (P. T. Cleve) Heiden, P. heimii Manguin, P. delicatissima (P. T. Cleve) Heiden, P. pseudo‐delicatissima (Hasle) Hasle, and P. americana (Hasle) Fryxell were screened with a suite of 15 putative species‐specific probes. Of those, a subset of eight probes was found that distinguished each species tested. In addition, Pseudo‐nitzschia chloroplasts were labeled with a probe directed against a eubacterial‐conserved sequence. Identification of new cultures based on their reactivity toward a set of probes agreed with species designations as defined by morphological criteria. Whole‐cell hybridization is a rapid, simple, and cost‐effective technique for discriminating among cultured Pseudo‐nitzschia species.
TAXONOMY OF THE FLATTENED SOLIERIACEAE (RHODOPHYTA) IN BRAZIL: AGARDHIELLA AND MERISTIELLA1
Authors: Guimarães Silvia M. P. B. , Oliveira Eurico C.
Published: October 2004

Taxonomic studies of an extensive collection of flattened members of the Solieriaceae considered by many authors to be species of Agardhiella, Eucheuma, Meristotheca, and Meristiella lead us to conclude that they represent only two genera in Brazil: Agardhiella, including A. ramosissima (Harvey) Kylin and A. floridana (Kylin) Gabrielson ex Guimarães et Oliveira, and Meristiella, with only one species, M. gelidium (J. Agardh) Cheney et Gabrielson. Accordingly, we propose that 1) Meristotheca gigartinoides Joly et Ugadim be synonymized with Agardhiella floridana, and 2) Meristiella echinocarpa (Areschoug) Cheney et Gabrielson and M. schrammii (P. et H. Crouan) Cheney et Gabrielson be synonymized with Meristiella gelidium.
MORPHOLOGY AND ECOLOGY OF THE MARINE BENTHIC DINOFLAGELLATE SCRIPPSIELLA SUBSALSA (DINOPHYCEAE)1
Authors: Faust Maria A.
Published: October 2004

The thecal surface morphology of Scrippsiella subsalsa (Ostenfeld) Steidinger et Balech was examined using the scanning electron microscope. This species is distinguished by a number of morphological characteristics. Apical plate 1′ is wide, asymmetric, and pentagonal, and it ends at the anterior margin of the cingulum. Intercalary plates 2a and 3a are separated by apical plate 3′. The apical pore complex includes a large Po plate with a raised dome at the center and a deep canal plate with thickened margins at plates 2′, 3′, and 4′. The intercalary bands are wide and deeply striated. The cingulum is deep, formed by six cingular plates; its surface is transversely striated and aligned with a row of minute pores. The cingular list continues around postcingular plate 1′” to form a sulcal list. The sulcal list is a flexible ribbon with a rounded tip that protrudes posteriorly, partially covering the sulcal plates. The hypotheca is lobed, and the antapical plates are irregularly shaped and wide in antapical view. The thecal surface is vermiculate to reticulate. A comparison in morphology and ecology is presented between S. subsalsa and other known Scrippsiella species.
SILICEOUS SCALE PRODUCTION IN CHRYSOPHYTE AND SYNUROPHYTE ALGAE. I. EFFECTS OF SILICA‐LIMITED GROWTH ON CELL SILICA CONTENT, SCALE MORPHOLOGY, AND THE CONSTRUCTION OF THE SCALE LAYER OFSYNURA PETERSENII1
Authors: Sandgren Craig D. , Hall Shirley A. , Barlow Steven B.
Published: October 2004

The cells of synurophyte flagellates (algal class Synurophyceae, formerly included in the Chrysophyceae) are enclosed within a regularly imbricate layer of ornamented siliceous scales. Scale morphology is of critical taxonomic importance within this group of algae, and the scales are valuable indicator microfossils in paleolimnological studies. The data presented here demonstrate that scale morphology and the integrity of the scale layer can exhibit extreme variability in culture as a function of the cellular quota of silica under silica‐limited growth. Silica‐limited, steady‐state populations of the colonial flagellateSynura peterseniiKorsh. were maintained over a range of specific growth rates (μ= 0.11–0.69 days−1) and silica cell quotas (Qsi= 0.13–2.40 pmoles Si · cell1). Scale morphology and the organization of the scale layer became increasingly aberrant as silica stress increased. Under severe stress, scale deposition was completely suppressed so that cells appeared scale‐free. This depression of scale deposition was reversible; populations of silica‐starved, scale‐free cells rapidly regenerated new scale layers when placed in batch culture and spiked with dissolved silica. During recovery from silica stress, cell division was repressed for 24 h while mean cell silica quota increased 25‐fold. The first new scales appeared within 2 h after the silica addition, and development of the new scale layer proceeded in an approximately synchronous manner, residting in normal scale layers on virtually all cells after 48 h of recovery in Sirich medium. Silica content of silica‐repleteSynuracells is comparable to freshwater diatoms of siynilar size, butSynurahas much greater potential quota variability than diatoms and no apparent threshold silica requirement. Silica‐limited growth kinetics and competition between diatoms andSynurafor silica are discussed.

The results suggest that morphological variability of siliceous scales in natural populations of synurophyte flagellates may result from silica stress and that the experimental approach developed here has great potential value as a means for circumscribing ecotypic variation in scale morphology. Results also demonstrate that scale production can be uncoupled from cell division, suggesting that cell cycle regulation of silica biomineralization in the Synurophyceae may be fundamentally different from that of diatoms (algal class Bacillariophyceae). This experimental system has application in the future study of the intracellular membrane systems and the regulatory processes involved in silica biomineralization.
QUANTITATIVE METHOD FOR DETERMINING A REPRESENTATIVE ALGAL SAMPLE COUNT1
Authors: Pappas Janice L. , Stoermer Eugene F.
Published: October 2004

A method for determining a representative count of a sample dependent on number of species is presented for application to various algal communities. Constant species curves are calculated as efficiency = (number of individuals–number of species)/number of individuals and diagrammed on a plot of efficiency versus number of individuals counted. Efficiency is defined as the probability that a new species encountered is minimal. That is, as the ratio of number of species to number of individuals approaches 1, more individuals will need to be counted in order to achieve a representative count. Data and calculations of efficiency from two algal communities are presented for illustration.
PHOTOSYNTHESIS AND REGULATION OF RUBISCO ACTIVITY IN NET PHYTOPLANKTON FROM DELAWARE BAY1
Authors: MacIntyre Hugh L. , Geider Richard J. , McKay R. Michael
Published: October 2004

Net phytoplankton (> 20 μm) comprised 51 ± 9% of the total chlorophyll (Chl) in a Skeletonema costatum– dominated spring bloom in Delaware Bay. The net phytoplankton had low C:N and high protein: carbohydrate ratios, indicating that their growth was nutrient‐replete. Their photosynthetic responses were characterized by low specific absorption, low light‐limited and light‐saturated rates of photosynthesis, and high quantum yields, indicative of acclimation to low irradiance and internal self‐shading. High fucoxanthin: Chi ratios also indicated low light acclimation, but high photoprotective xanthophyll: Chi ratios suggested a high capacity for photoprotective energy dissipation. Ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) could be activated and deactivated in response to changes in irradiance and was fully activated at the surface of the water column and fully deactivated in aphotic deep water. Maximum Rubisco activity was correlated with Rubisco content and bulk protein content of the phytoplankton and with light‐saturated rates of photosynthesis measured in short (< 20‐min) incubations. Long (60‐min) incubations caused a decrease in the light‐saturated rate of photosynthesis, possibly because of feedback limitation. While feedback limitation is unlikely to occur in the water column, it should be considered when estimating productivity in well‐mixed waters from fixed light‐depth incubations.
A MODEL APPROACH FOR SIZE‐SELECTIVE COMPETITION OF MARINE PHYTOPLANKTON FOR FLUCTUATING NITRATE AND AMMONIUM1
Authors: Stolte Willem , Riegman Roel
Published: October 2004

Phytoplankton size‐selective competition for fluctuating nutrients was studied with the use of a numerical model, which describes nitrate and ammonium uptake, nitrate reduction to ammonium, and growth as a function of cell she under fluctuating nitrogen limitation. The only size‐dependent parameter in the model was the cell nutrient quota. Related to this, the cell surface area per biomass was negatively correlated to cell volume, and the vacuole volume per biomass ratio was positively correlated to cell volume. Simulations showed an inverse correlation between the maximum specific growth rate and cell size under steady‐state conditions. With nitrate as the limiting nitrogen source, nitrogen quotas were always higher than with ammonium at the same specific growth rate. Net passive transport of ammonium due to unspecific diffusion of ammonia across the plasma membrane decreased the affinity for ammonium, whereas the affinity for nitrate was not influenced. Transient state‐specific ammonium uptake was not dependent on cell size. However, small algae always have the highest specific growth rate in ammonium‐controlled systems according to our model. Transient state nitrate uptake rate was positively correlated to cell size because larger algae have a higher vacuole volume per biomass, in which nitrate can be stored. Despite their lower maximum growth rate, larger algae became dominant during simulations under fluctuating nitrate supply when amplitude of and the period between nitrate pulses were high enough. Results from model simulations were qualitatively validated by earlier observations that large diatoms become dominant under fluctuating conditions when nitrate is the main nitrogen source.
PHYSIOLOGICAL AND OPTICAL PROPERTIES OF RHIZOSOLENIA FORMOSA (BACILLARIOPHYCEAE) IN THE CONTEXT OF OPEN‐OCEAN VERTICAL MIGRATION1
Authors: Richardson Tammi L. , Ciotti Áurea M. , Cullen John J. , Villareal Tracy A.
Published: October 2004

Cultures of Rhizosolenia formosa H. Peragallo were studied to assess whether or not physiological and optical characteristics of this large diatom were consistent with the ability to migrate vertically in the open ocean. Time‐course experiments examined changes in chemical composition and buoyancy of R. formosa during nitrate (N)–replete growth, N starvation, and recovery. Cells could maintain unbalanced growth for at least 53 h after depletion of ambient nitrate. Increases in C:N and carbohydrate: protein ratios observed during N starvation reversed within 24 h of reintroduction of nitrate to culture medium. Buoyancy was related to nutrition: Upon N depletion, the percentage of positively buoyant cells decreased to 4% from 11% but reverted to 9% within 12 h of nitrate readdition. Cells took up nitrate in the dark. Nitrogen‐specific uptake rates averaged 0.48 d−1; these rates were higher than N‐specific growth rates (0. 15 d−1), indicating the potential for luxury consumption of nitrate, which can be stored for later use. Measurements of photosynthesis vs. irradiance, chlorophyll‐specific absorption (aph*(λ)), and pigment composition showed that cells may be adapted for growth under a wide range of irradiances. Values of aph*(λ) were lower for N‐depleted cells than for N‐replete cells, and N‐depleted cells had higher ratios of total carotenoids to chlorophyll a. Aggregation of chloroplasts was more pronounced in N‐depleted cells. These are possibly photoprotective mechanisms that would be an advantage to N‐depleted cells in surface waters. Compounds that absorb in the ultraviolet region were detected in N‐replete cells but were absent in N‐depleted cultures. Overall, these results have important implications for migrations of Rhizosolenia in nature. Cells may survive fairly long periods in N‐depleted surface waters and will continue to take up carbon; then they can resume nitrate uptake and revert to positive buoyancy upon returning to deep, N‐rich water. Uncoupled uptake of carbon and nitrogen during migrations of Rhizosolenia is a form of new production that may result in the net removal of carbon from oceanic surface waters.
MACROALGAL RESPONSES TO NITROGEN SOURCE AND AVAILABILITY: AMINO ACID METABOLIC PROFILING AS A BIOINDICATOR USING GRACILARIA EDULIS (RHODOPHYTA)1
Authors: Jones Adrian B. , Dennison William C. , Stewart George R.
Published: October 2004

The use of macroalgae as biological indicators of dissolved nutrient source and availability in the water column was investigated. Total tissue nitrogen (N) content, pigments, and amino acids of the red alga Gracilaria edulis (Gmelin) Silva were compared to N source and availability in laboratory and field incubations to identify responses that would serve as bioindicators of N. Field‐collected algae were preincubated (6–8 wk) in low‐nutrient seawater to deplete their luxury reserves ofN. Incubations were then conducted for periods of 3 d in laboratory aquaria (N‐spiked seawater) and in the field using macroalgal incubation chambers. After incubation in different N sources (NH4+, NO3−, and urea) in laboratory aquaria, photosynthetic pigments (phycoerythrin and chlorophyll a) and total tissue N increased, in response to increasing [NH4+] but not to [NO3−] or [urea]. Incubation in two ranges of [NH4+], one from 0 to 80 μM and the other from 0 to 800 μM, in laboratory aquaria increased the total amino acid pool. Citrulline concentrations were the most responsive to [NH4+] (r2= 0. 84). NH4+ source treatments produced increases in citrulline, phenylalanine, serine, and free NH4+ and decreases in alanine; NO3− treatments produced increases in glutamic acid, citrulline, and alanine; and urea treatments produced increases in free NH4+ and decreases in phenylalanine and serine. The observed variations in amino acid content facilitated the development of an index for each N source based on relative concentrations of various amino acids (i. e. metabolic profiling). Gracilaria edulis was incubated along a field N gradient in the Brisbane River (three sites) and Moreton Bay (four sites), Queensland, Australia. Both phycoerythrin and tissue N appeared to respond equally to NH4+ and NO3− availability in the field. N source indices, based on amino acid concentration, were effective predictors of both [NH4+] and [NO3−] over a wide range of concentrations along the field gradient. Macroalgal physiological responses, particularly amino acid content, to changes in source and availability of N appear to be useful as sensitive bioindicators of N.
GROWTH PATTERN, REPRODUCTION, AND SELF‐THINNING IN SEAWEEDS1
Authors: Flores‐Moya Antonio , Fernández José A. , Niell F. Xavier
Published: October 2004

In unispecific plant stands, the logarithm of mean individual weight (w) depends on the logarithm of density (d) by the ‐3/4 power law (a slope of ‐1.5 and an intercept ranging from 2.3 to 5.0). The analysis of the w and d relationships in whole cohorts of two seaweed species from the Strait of Gibraltar shows deviations from the canonical equation. The kelp Phyllariopsis purpurascens (C. Agardh) Henry et South (Phaeophyta) growing at a 30‐m depth has the lowest intercept value (0.6) recorded for any plant species and a slope not significantly different from ‐1.5. The slope value is in accordance with those found in species whose growth is not stopped by reproduction. Irradiance under a single layer of blades was lower than the photosynthetic light compensation point, and this could be due to overdispersion of the shoots and, in consequence, to the low intercept value of the self‐thinning equation. The w to d relationships in Asparagopsis armata Harvey (Rhodophyta) show two different components: no dependence between these two variables (slope not significantly different from 0) at densities < 500 shoots·m−2, and a slope more negative (‐2.1) than proposed by the ‐3/2 power law at densities > 500 shoots·m−2. The pattern at high densities could be due to intraspecific competition for light, whereas the slope ∼0 at low densities could be related to inhibition of growth by reproduction (cystocarp and carpospore production). Therefore, rather than being considered exceptional, we suggest that a gradient of variability could be expected in the dependence of w on d when specific growth patterns and reproduction are considered.
COLONIZATION AND REPRODUCTION OF THE EPIBIOTIC FLAGELLATE COLACIUM VESICULOSUM (EUGLENOPHYCEAE) ON DAPHNIA PULEX1
Authors: Al‐Dhaheri Rowaya S. , Willey Ruth L.
Published: October 2004

The epibiotic flagellate Colacium vesiculosum Pringsheim attaches to planktonic species of Daphnia in freshwater habitats. Previous studies found that prevalence (percentage of substrate organisms carrying attached epibionts) and intensity (number of attached epibionts on a given substrate organism) are low early in the Daphnia intermolt period and are high late in the intermolt period. We tested the hypothesis that increases of Colacium cells attached to Daphnia occur both by rapid initial and continuous colonization and by cell reproduction. Epibiont prevalence and intensities were determined at successive intermolt stages of Daphnia pulex Leydig collected from freshwater ponds in Colorado. Colonization was continuous throughout the intermolt period and was most important to epibiont population increase at the beginning of the intermolt period. Cell division was the major contributor to epibiont increase at the end of the intermolt period.