bluuebunny/crossref_metadata_2025 huggingface dataset:
THE CHITINOUS NATURE OF FILAMENTS EJECTED BY PHAEOCYSTIS (PRYMNESIOPHYCEAE)1
Authors: Chrétiennot‐Dinet Marie‐JosèPhe , Giraud‐Guille Marie‐Madeleine , Vaulot Daniel , Putaux Jean‐Luc , Saito Yukie , Chanzy Henri
Published: October 2004

Filaments ejected by Phaeocystis globosa Scherffel, organized in star‐like structures, were observed and analyzed before and after their discharge from cells. Ultrastructural observations obtained after cryofixation and cryosubstitution led to a model for their storage within the cell and for their ejection from the cell. Electron diffraction analysis on the ejected filaments demonstrated their chitinous composition. This technique indicated without ambiguity that each filament was in fact a whisker‐like α‐chitin crystal, with the axes of the corresponding polymer chains aligned with the filament's axis. X‐ray microanalysis of the mats of filaments indicated that the silica content suggested by earlier workers was an artifact resulting from the filtration procedure.
GROWTH‐CONTROLLED OSCILLATION IN ACTIVITY OF HISTONE H1 KINASE DURING THE CELL CYCLE OF CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1
Authors: Zachleder Vilém , Schläfli Oliver , Boschetti Arminio
Published: October 2004

Synchronous cultures of the cell wall‐less mutant Chlamydomonas reinhardtii Dangeard cw 15 were grown under different mean irradiances and different illumination regimes, which produced cell cycles that differed in the number of daughter cells released from one mother cell, in the length of the cell cycle, and in the growth rate. During the cell cycle, the cells reached several commitment points whose number and timing differed according to the particular pattern of the cell cycle. The cell volume was used as a growth parameter and increased in a stepwise manner. Each of the steps consisted of periods of both fast and slow growth. Growth usually stopped when the cells attained a volume twice that of the preceding step. Reaching particular commitment points was coupled with the position of these points in the enlargement of cell volume. Changes in the activity of histone H1 kinase were noted during the cell cycles of all experimental variants, and the activities were compared with the timing of various commitment points. It was found that kinase activity varied markedly within a single cell cycle, attaining maximal values when the cellular volume had doubled. Each peak in kinase activity slightly preceded the commitment to an individual sequence of reproductive events. In addition to the oscillations related to cell growth, a peak of kinase activity always occurred toward the end of the cell cycle when multiple rounds of DNA replication, mitosis, and cell division occurred.
TWO MORPHOLOGICALLY SIMILAR BIOLOGICAL SPECIES: CHONDRUS PINNULATUS AND C. ARMATUS (GIGARTINACEAE, RHODOPHYTA)1
Authors: Brodie Juliet , Masuda Michio , Mine Ichiro , Guiry Michael D.
Published: October 2004

The nature of the relationship between Chondrus pinnulatus (Harvey) Okamura f. pinnulatus and C. pinnulatus f. armatus (Harvey) Yamada et Mikami (Gigartinaceae, Rhodophyta) was investigated by comparative analysis of their biogeography, phenologies, life histories, gross and vegetative morphology, crossability, and upper thermal tolerance. The forma pinnulatus has a more northerly distribution in Japan and adjacent waters, exhibiting adaptation to the cooler regions, whereas the forma armatus has a more southerly range. The latter may be the result of a higher thermal tolerance. Both formae have a Polysiphonia‐type life history and are similar in their internal vegetative morphology. They can, however, be distinguished by gross morphology: forma pinnulatus has wide, flattened axes, compressed to flattened ultimate segments and proliferations, while forma armatus has narrow, compressed to subterete axes and subterete to terete ultimate segments and proliferations. These differences persist in laboratory culture. All intraformae crosses were positive, with carpospores from the cross developing into fertile F1 tetrasporophytes releasing tetraspores that developed into dioecious F1 gametophytes, the female gametophytes of which formed normal cystocarps. This suggests that members of populations of each forma freely interbreed. Among interformae crosses, only some offspring derived from geographically distant strains bore normal cystocarps in the F1 female gametophytes. Other crosses showed that interbreeding between populations of these two formae was blocked by various isolating mechanisms: incompatibility, hybrid inviability, and hybrid sterility. Reproductive isolation between f. pinnulatus and f. armatus is virtually complete in wild populations, because hybrid populations have not been found in the wild. In addition, these two entities can be considered biological species that are also referred to the taxonomic species, C. armatus and C. pinnulatus, because they do not overlap with regard to the morphology of the ultimate segments and proliferations. Subtle (but significant) gross morphological differences, partial interfertility between the two species, and deleterious hybridization in the area in which they occur sympatrically suggest that their evolutionary divergence was relatively recent.
DNA EXTRACTION AND RAPD MARKERS TO ASSESS THE GENETIC SIMILARITY AMONG GELIDIUM SESQUIPEDALE (RHODOPHYTA) POPULATIONS1
Authors: Alberto Filipe , Santos Rui , Leitão José M.
Published: October 2004

A simple method developed for genomic DNA isolation from fungus was tested on the red alga, Gelidium sesquipedale (Clem.) Born et Thur., which is commercially exploited for its high sulfated polysaccharide (agar) content. This method is faster, cheaper, and less toxic than conventional phenol/chloroform methods. Random amplified polymorphic DNA (RAPD) amplifications were performed successfully without the necessity of purifying the DNA. RAPD markers were used to investigate the genetic similarity among three natural populations of G. sesquipedale from southern Portugal. Bulked‐genomic DNA samples of 15 different individuals were made in each population. These can be conceived of as a sample of the population DNA. Of the 62 primers screened, 41 produced bands and 22 revealed polymorphisms. Genetic similarities among populations were high. Populations that are further away from each other have the lowest similarity coefficients, whereas the intermediate Ingrina population, located on the south coast, showed higher genetic similarity with the Odeceixe population located on the southwest coast, than with the São Rafael southern population. This suggests a higher genetic flow between Odeceixe and Ingrina or the result may be a founder effect in the sense that the species has propagated from the east coast to the south coast of Portugal. We conclude that the use of this isolation method with RAPD analysis is appropriate to characterize the genetic variability of this commercial species along its geographical distribution. Large sample sizes can be screened at a relatively low cost. Finding genetic markers for commercial populations of G. sesquipedale may be of industrial interest.
ICE NUCLEATION IN SEAWEEDS IN RELATION TO VERTICAL ZONATION1
Authors: Lundheim Rolv
Published: October 2004

The ice nucleation temperatures of thallus fragments of different macroalgal species were investigated. The samples were collected from the littoral zone on a rocky shore in Trondheimsfjord, central Norway. Thallus fragments of species growing in the upper parts of the eulittoral zone had lower ice nucleation temperatures than those of species living in the lower eulittoral zone and in the upper sublittoral zone. Samples collected in the winter had lower nucleation temperatures than samples from the same species collected in the summer, which indicates that the seaweeds are removing or inactivating ice nucleators as a part of their cold hardiness strategy.
EPIPHYTE‐GRAZER INTERACTIONS ON ZOSTERA MARINA (ANTHOPHYTA: MONOCOTYLEDONES): EFFECTS OF DENSITY ON COMMUNITY FUNCTION1
Authors: Nelson Timothy A.
Published: October 2004

Interactions between algal epiphytes and their grazers can have a significant impact on the structure and function of eelgrass (Zostera marina L.) meadows. In Puget Sound, the herbivorous gastropod Lacuna variegata Carpenter and its congeners appear to remove large quantities of the epiphytic community from eelgrass blades. When snails at typical field densities were used in microcosms, Lacuna significantly reduced epiphytic biomass and areal productivity. Biomass‐specific productivity of the epiphytic community showed an increasing trend with increasing snail density. Epiphytic productivity increased nonlinearly with increasing epiphytic biomass. The commonly used logistic population growth formula adequately described this relationship. Grazing rate also increased nonlinearly with increasing epiphytic biomass. The Hailing equation adequately described the relationship between grazing rate and epiphytic biomass. The proportion of the epiphytic biomass found on the oldest blade of an eelgrass shoot was related linearly to epiphytic biomass, suggesting that a constant fraction of the epiphytic community is lost regardless of epiphytic density. Lacuna clearly removed large quantities of epiphytic material from eelgrass blades, significantly altering community function. Modified Lotka‐Volterra equations, incorporating the logistic growth form and Hailing grazing equation, should prove useful in modeling the epiphyte–grazer interaction.
SEASONAL VARIATION OF PHOTOSYNTHETIC PERFORMANCE AND LIGHT ATTENUATION INULVACANOPIES FROM PALMONES RIVER ESTUARY1
Authors: Vergara Juan J. , Pérez‐Lloréns J. Lucas , Peralta Gloria , Hernández Ignacio , Niell F. Xavier
Published: October 2004

The primary production ofUlvapopulations relies on their photosynthetic performance, which is dependent on the light availability under natural conditions. This study concerns the light attenuation characteristics inUlvacanopies and the seasonal photosynthetic performance of two different species (Ulva rotundataBlid.,Ulva curvata(Kütz.) De Toni) blooming in the Palmones river estuary. Light within canopies differed from that reaching the surface. Light availability was reduced through the water column (at high tide) andUlvacanopies. In addition, light was spectrally filtered. As a result, the photosynthetically usable radiation (PUR) was further attenuated throughUlvacanopies, increasing the photosynthetically active radiation/PUR ratio. The muddy sediment deposited on and between theUlvathalli also drastically restricted the light availability. ThickUlvamats are frequently found covering the intertidal mudflats, and therefore, thalli within these mats may be subjected to steep light gradients. As a consequence, individualUlvagrowth rates cannot be extrapolated to estimate the primary production ofUlvacanopies. Interspecific differences were observed for light‐saturated photosynthetic rates (Pmax) and light compensation points (LCP), withUlva curvatagenerally displaying higher values than didU. rotundata. For both species, maxima were recorded in winter for Pmax, quantum yield, chlorophyll content, and absorptance, whereas minima were found in summer. Dark respiration (Rd) was not seasonally affected, and a maximum LCPwas found in summer. To extrapolate these data to field situations, the temperature dependence of photosynthesis should be considered. The Q10values were 2.44 for Rdand 1.79 for Pmax, whereas the photosynthesis rate at subsaturating light levels was unaffected. The Q10values showed an enhanced respiratory rate in summer and a minimum in winter, whereas the seasonal differences on Pmaxwere damped.
ANTIOXIDATIVE PROTECTION OF PERIDINIUM GATUNENSE IN LAKE KINNERET: SEASONAL AND DAILY VARIATION1
Authors: Butow Barbara J. , Wynne David , Tel‐Or Elisha
Published: October 2004

A comprehensive antioxidative mechanism was found in the freshwater dinoflagellate Peridinium gatunense Lemm. during the spring bloom in Lake Kinneret. Ascorbate was present throughout the bloom period and was responsible, together with catalase, for the elimination of photosynthetically produced H2O2. As glutathione concentrations and ascorbate regenerative enzymes were negligible during mid‐spring, ascorbate was presumably biosynthesized during the photosynthetically active period. Antioxidative activity increased overall at the end of the spring in conjunction with elevated ambient stress conditions, for example high light. Under such circumstances, ascorbate was regenerated. Ascorbate levels doubled when cells were exposed to an increase in irradiance from 60 to 600 μmol photons·m−2·s−1, and on addition of H2O2, concentrations increased a further 20‐fold. Significant antioxidative activity was also noted in the dark, although this was dependent on the presence of H2O2. Diurnal changes in antioxidants and their regenerative enzymes were observed. The activities of mono‐dehydroascorbate reductase, glutathione reductase, and ascorbate concentrations showed ultraradian periodicity and were completely in phase throughout the day/night period. Dehydroascorbate reductase activity and glutathione concentrations were also in phase but showed aperiodic variation, as did ascorbate peroxidase activity. Superoxide dismutase and catalase activities were generally out of phase during the 24‐h period but did show ultraradian periodicity. Lake samples entrained under constant light revealed an inate 12‐h rhythm for catalase activity, during at least 36 h.
SUPEROXIDE DISMUTASE ACTIVITY IN PERIDINIUM GATUNENSE IN LAKE KINNERET: EFFECT OF LIGHT REGIME AND CARBON DIOXIDE CONCENTRATION1
Authors: Butow Barbara J. , Wynne David , Tel‐Or Elisha
Published: October 2004

The activity of superoxide dismutase (EC 1.15.1.1, superoxide: superoxide oxidoreductase) (SOD) was determined in Peridinium gatunense Lemm. under natural and controlled conditions. SOD activity increased toward the end of the spring algal bloom in Lake Kinneret simultaneously with maximal photosynthetic activity and conditions of elevated ambient stress such as high irradiance. Activity staining of native polyacrylamide gel electrophoresis gels of bloom samples showed a similar pattern to the spectrophotometrically measured SOD. Both Mn SOD and CuZn SOD were present, however no Fe SOD was found in Peridinium. One of three isoenzymes of Mn SOD showed marked differential regulation of activity under stress. An increase in the quantity of the 32‐kDa Mn SOD polypeptide during the bloom was found to be unrelated to senescence; it was assumed that this polypeptide was induced by stress. Thus, SOD in Peridinium undergoes physiological and molecular acclimation to seasonal environmental changes. When Peridinium was exposed to various O2 and CO2 concentrations in culture, CuZn SOD significantly increased under high C02 concentrations and normoxic conditions (20% O2). However, at high irradiances, Peridinium cultures exposed to low and high CO2 concentrations also had similar CuZn SOD activity. It was concluded that stressful irradiance is the overriding cause of increased SOD activity in both lake samples and in cultures of Peridinium.
INTERACTION OF NITROGEN FIXATION AND PHOSPHORUS LIMITATION IN APHANIZOMENON FLOS‐AQUAE (CYANOPHYCEAE)1
Authors: De Nobel W. T. (Pim) , Snoep Jacky L. , Westerhoff Hans V. , Mur Luuc R.
Published: October 2004

The effect of simultaneous nitrogen fixation and phosphorus limitation on the physiological adaptation and growth performance of Aphanizomenon flos‐aquae (L.) Ralfs PCC 7905 was studied in continuous culture. In the absence of ammonia, N2 fixation occurred and the maximum growth rate (as determined in diluted batch cultures) was lower. However, no distinction could be made between the steady‐state N uptake rates (based on cellular N contents) of N2‐fixing cells and cells grown with ammonia. At the higher dilution rates, the residual P concentration increased with increasing dilution rate, more so under N2‐fixing conditions, compared to the cultures grown in the presence of ammonia. More generally, the yield of biomass per consumed P, as the biomass concentration itself, decreased with increasing dilution rate, and both were lower under N2‐fixing conditions. The restricted biomass production under N2‐fixing conditions suggests that reduction of N loading may benefit lake restoration projects. The influence of N2‐fixation on the severity of P limitation is discussed in terms of metabolic control analysis. From the increase of the residual P concentration on switching from ammonium to N2‐fixing conditions, it is deduced that under N2‐fixing and P‐limited conditions, control of growth is shared by N and P metabolism.
ACCLIMATION OF SYNECHOCOCCUS STRAIN WH7803 TO AMBIENT CO2 CONCENTRATION AND TO ELEVATED LIGHT INTENSITY1
Authors: Hassidim Miriam , Keren Nir , Ohad Itzhak , Reinhold Leonora , Kaplan Aaron
Published: October 2004

A CO2 concentrating mechanism has been identified in the phycoerythrin‐possessing Synechococcus sp. WH7803 and has been observed to be severely inhibited by short exposure to elevated light intensities. A light treatment of 300–2000 μmol quanta·m−2·s−1 resulted in a considerable decay in the variable fluorescence of PSII with time, suggesting decreased efficiency of energy transfer from the phycobilisomes, direct damage to the reaction center II, or both. Measurements of the activity of PSII and changes in fluorescence emission spectra during a light treatment of 1000 μmol quanta·m−2·s−1 indicated considerable reduction in the energy flow from the phycocyanin to the phycobilisome terminal acceptor and chlorophyll a. Consequently, whereas the maximal photosynthetic rate, at saturating light and Co2 concentration, was hardly affected by a light treatment of 1000 μmol quanta·m−2·s−1 for 2 h, the light intensity required to reach that maximum increased with the duration of the light treatment.
GROWTH, DARK RESPIRATION AND PHOTOSYNTHETIC PARAMETERS OF THE COCCOLITHOPHORID EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) ACCLIMATED TO DIFFERENT DAY LENGTH‐IRRADIANCE COMBINATIONS1
Authors: Nielsen Marianne V.
Published: October 2004

Growth, dark respiration rate, photosynthetic parameters, and chemical composition were determined for Emiliania huxleyi (Lohmann) Hay et Mohler acclimated to different combinations of day length (12, 18, 24 h) and irradiance (30, 100, 200, 800 μmol·m−2·s−1). Specific growth rate (μ, day−1) and carbon‐specific dark respiration rate (rCd, day−1) were independent of day length, but increased significantly with increasing irradiance. The photosynthetic parameters depended on the initial acclimation day length and irradiance: Chlorophyll a‐specific maximum photosynthetic rate (PmB) increased up to threefold with decreasing day length and twofold with increasing irradiance. The maximum light utilization coefficient (αB) and maximum quantum yield (φm) increased up to threefold with decreasing day length. αB increased almost four‐fold with decreasing irradiance, whereas φm was independent of irradiance. Literature data for phytoplankton indicate that PmB consistently increases with increasing irradiance, and day length‐irradiance responses of αB and φm are species specific. Results from the present experiment and other studies indicate that if day length‐irradiance variability in the photosynthetic parameters are neglected, this may cause an over‐ or underestimation up to a factor of two in the photosynthetic rate estimation based on these parameters.
IMMUNOLOCALIZATION OF CENTRIN DURING FERTILIZATION AND THE FIRST CELL CYCLE IN FUCUS DISTICHUS AND PELVETIA COMPRESSA (FUCALES, PHAEOPHYCEAE)1
Authors: Bisgrove Sherryl R. , Nagasato Chikako , Motomura Taizo , Kropf Darryl L.
Published: October 2004

Antibodies that recognize the centrosome‐associated protein centrin were used to characterize centrosomal origin and positioning during fertilization and the first cell cycle in Fucus distichus subsp. evanescens (C. Agardh) Powell and Pelvetia compressa (J. Agardh) De Toni. Centrin was identified in sperm, eggs, and zygotes on protein blots, indicating the protein is present in both gametes. Using immunofluorescence microscopy, centrin was found in discrete foci in sperm. In contrast, eggs lack centrosomes and centrin was not detectable by immunofluorescence, indicating that centrin was probably dispersed in the cytoplasm. Two foci of centrin were present on the nuclear envelope of zygotes, but microtubules remained dispersed over the zygotic nucleus. Centrin foci separated over the nuclear envelope as the first cell cycle progressed. Microtubules became concentrated at the centrin foci to form centrosomes that gave rise to the spindle poles at mitosis.
PASSAGE OF A MARINE BROWN ALGAL DNA VIRUS FROM ECTOCARPUS FASCICULATUS (ECTOCARPALES, PHAEOPHYCEAE) TO MYRIOTRICHIA CLAVAEFORMIS (DICTYOSIPHONALES, PHAEOPHYCEAE): INFECTION SYMPTOMS AND RECOVERY1
Authors: Maier Ingo , Rometsch Elke , Wolf Susanne , Kapp Markus , Müller Dieter G. , Kawai Hiroshi
Published: October 2004

A dsDNA virus (EfasV‐1) isolated from Ectocarpus fasciculatus Harvey infected Myriotrichia clavaeformis Harvey, a species belonging to a different brown algal order. The virus did not complete its infection cycle in the foreign host but caused infertility due to malformed reproductive structures. After some time in culture, the host's reproductive capacity was sometimes restored with concomitant loss of at least part of the viral genome. This incidence of interordinal virus transfer is discussed in relation to possibilities for virus‐mediated horizontal gene transfer in brown algae.
CARBONIC ANHYDRASE IN THE MARINE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1
Authors: Roberts Samantha B. , Lane Todd W. , Morel François M. M.
Published: October 2004

The zinc metalloenzyme carbonic anhydrase plays a critical role in inorganic carbon acquisition in marine diatoms, thus conferring on zinc a key role in oceanic carbon cycling. As a first step in determining the location and function of carbonic anhydrase (CA) in Bacillariophyceae, we purified and partially sequenced CA from T. weissflogii (Gru) Fryxell et Hasle (TWCA1) and cloned the corresponding cDNA (twca1). The twca1 sequence is different from other known algal carbonic anhydrase genes, and encodes a protein of roughly 34 kDa. The amino terminal amino acids sequenced from purified TWCA1 are 72 residues downstream of the putative starting methionine predicted by twca1. This difference may be due to the presence of a short‐lived signal sequence designed to guide the enzyme to the correct cellular location. The absence of any homology between TWCA1 and previously sequenced CAs from Chlorophyceae may indicate either convergent evolution or that carbon acquisition represents a fundamental physiological difference among algal phyla.
PHYLOGENETIC ANALYSIS OF MORPHOLOGICAL SPECIES OF CARTERIA (VOLVOCALES, CHLOROPHYTA) BASED ON rbcL GENE SEQUENCES1
Authors: Nozaki Hisayoshi , Ito Motomi , Watanabe Makoto M. , Takano Hiroyoshi , Kuroiwa Tsuneyoshi
Published: October 2004

Four related species in the unicellular volvocalean genus Carteria [C. crucifera Pascher, C. eugametos Mitra, C. inversa (Korshikov) Bourrelly and C. cerasiformis Nozaki et al.] were delineated on the basis of recent comparative light and electron microscopy of a large number of culture strains. However, the species thus delineated may not represent natural or monophyletic entities. In the present study, 1128 base pairs of the chloroplast protein‐coding gene (large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase gene) from 12 Carteria strains representing the four species as well as from related volvocalean species were analyzed to elucidate the phylogenetic status of the taxonomic or morphologic species of Carteria. The sequence data showed that the 12 Carteria strains exhibit four robust monophyletic groups which are strictly consistent with the four taxonomic species. These results are discussed in relation to contrasting results found in other microalgal genera. It is concluded that phylogenetic analysis, based on DMA sequence data and comparative morphologic characterization of species and using a large number of culture strains, is essential to a natural system of microalgal species taxonomy.
SINGLE LOCUS MICROSATELLITES IN GRACILARIALES (RHODOPHYTA): HIGH LEVEL OF GENETIC VARIABILITY WITHIN GRACILARIA GRACILIS AND CONSERVATION IN RELATED SPECIES1
Authors: Wattier Rémi , Dallas John F. , Destombe Christophe , Saumitou‐Laprade Pierre , Valero Myriam
Published: October 2004

Four single locus microsatellites identified in the red alga Gracilaria gracilis (Stackhouse) Steentoft, Irvine, et Farnham (Rhodophyta) were examined for allelic diversity at different spatial and taxonomic levels. First, because simple morphological diagnostic characters are often missing within the Gracilariaceae, we developed a simple and rapid method based on rDNA ITS size variation in order to verify the taxonomic status of the samples used in this study. All European (including Mediterranean samples), Argentinian, and Namibian samples used in our study were confirmed to be a homogenous G. gracilis group. By contrast, our results on rDNA ITS sizes showed that Gracilaria from Japan, initially identified as G. gracilis, was different from the rest of the G. gracilis group. Secondly, microsatellite polymorphism and conservation at the species level was tested on the worldwide collection of G. gracilis and within a single population. The loci Gv1AAG and Gv1AAC showed no allelic variation, whereas two others, Gv1CT and Gv2CT, were highly polymorphic. All microsatellite loci were conserved within G. gracilis, except in the sample from Japan. The taxonomic status of G. gracilis from Japan is thus questionable. This study revealed a high level of within‐population polymorphism (52 alleles for Gv1CT and 12 for Gv2CT). Moreover, the combination of these two loci was shown to be very powerful for identifying individuals within a population, that is, 93% of the individuals were characterized by a unique genotype. Finally, conservation of the four loci was tested in taxonomically related species of Gracilaria (G. chilensis, G. pacifica, and G. tikvahiae) and two Gracilariopsis species (Gs. sp. and Gs. longissima). The results suggest that the polymorphic locus Gv2CT may provide a valuable genetic marker within the different species of the Gracilariaceae.
PORGUENIA PERUVIANA GEN. ET SP. NOV., A MARINE CENTRIC DIATOM WITH AN UNUSUAL OCELLUS1
Authors: Sullivan Michael J.
Published: October 2004

A new diatom genus and species, Porguenia peruviana Sullivan, is described from an Eocene marine deposit from the Paracas Peninsula, Peru. The valve outline is circular and the areolation is best described as pseudoloculate; spines of any type are lacking. A ring of elongated, densely packed rimoportulae is situated on the secondary marginal ridge. Externally, each rimoportula consists of a long, flattened, fluted upper portion supported by a shorter cylindrical stalk. The processes are winged and exhibit various degrees of curvature of the major axis. Typically, six reniform ocelli of unusual structure are situated centrifugally to the ring of rimoportulae and interrupt the true marginal ridge. Because the perforation plate differs from that of all other ocellus‐bearing diatoms, a new term has been introduced for this structure, the diaphoron. The placement and structure of this newly discovered “perforation plate” do not allow Porguenia to be placed in any circumscribed family, although the Triceratiaceae would appear at present to be the most closely related family.
GENETIC DIVERSITY WITHIN BALTIC SEA POPULATIONS OF NODULARIA (CYANOBACTERIA)1
Authors: Hayes Paul K. , Barker Gary L. A.
Published: October 2004

The determination of the genetic structure of microbial populations has, until recently, required the establishment of many independent clonal cultures for genotypic analysis. In such studies it has been necessary to assume that isolates able to grow in laboratory culture are representative of the full range of diversity within the natural population. In order to test this assumption we used the polymerase chain reaction (PCR) to amplify the intergenic spacer region of the Phycocyanin operon (PC‐IGS) from filaments of Nodularia taken both from clonal cultures and from natural populations in the Baltic Sea. Analysis of the nucleotide sequences revealed more variation among 16 cultured isolates than within 23 single filaments sampled from a natural population. As a means of rapidly determining population genetic structure we designed and used mixtures of allele‐specific amplification primers in diagnostic PCRs to identify which PC‐IGS allele was present in single filaments from natural cyanobacterial assemblages. Using this method, we determined the PC‐IGS genotype of 156 filaments from 9 sampling stations throughout the central basin of the Baltic Sea in July 1996. Our results show that two distinct genotypes of Nodularia are present in the population at all stations. Although the two types were present in approximately equal numbers, they were not distributed uniformly.
PRIMARY ADHESION OF ENTEROMORPHA (CHLOROPHYTA, ULVALES) PROPAGULES: QUANTITATIVE SETTLEMENT STUDIES AND VIDEO MICROSCOPY1
Authors: Callow Maureen E. , Callow James A. , Pickett‐Heaps Jeremy D. , Wetherbee Richard
Published: October 2004

Quantitative methods and associated kinetic analyses have been used for the first time to study detailed aspects of the settlement and adhesion of various types of Enteromorpha popagule. Time course experiments showed that quadri and biflagellate zoospores and zygotes adhered rapidly, but a proportion within any one population appeared to be incompetent at adhering to the substratum. Kinetic (Scatchard) analysis of adhesion experiments performed at a range of zoospore concentrations revealed density‐dependent effects not previously reported, with positive cooperativity at low spore densities and negative cooperativity at high spore densities. High‐resolution video microscopy was used for the first time to reveal details of the various stages in the settlement and adhesion of zoospores and zygotes. Novel observations were made of an initial, temporary phase of attachment via the apical papilla, followed by a permanent phase of commitment, characterized by discharge of adhesive‐containing cytoplasmic vesicles, as the cell contracted against the surface, and adsorption of flagella. The phase of commitment was followed by exploitation of the surface through amoeboid‐like movements at the interface. Gregarious settlement behavior was frequently observed leading to the formation of rafts of cells. The possible mechanisms and significance of density‐dependent spore adhesion are discussed.
EFFECTS OF ULTRAVIOLET RADIATION ON PHOTOSYNTHESIS IN THE SUBTROPICAL MARINE DIATOM, CHAETOCEROS GRACILIS (BACILLARIOPHYCEAE)1
Authors: Hazard Christina , Lesser Michael P. , Kinzie Robert A.
Published: October 2004

ARSTRACT

Acclimation to ambient ultraviolet radiation (UVR) was examined in a subtropical marine diatom, Chaetoceros gracilis Schutt. Short‐term exposure to UVR (<24 h) reduced the efficiency of photosynthetic energy conversion, carbon fixation, activity of 1,5‐bisphosphate carboxylase‐loxygenase (RUBISCO), and the rapid turnover of the putative Dl reaction center (32 kda) protein, whereas longer‐term exposure to ambient UVR (24–48 h) revealed a steady‐state acclimation, defined as recovery of carbon fixation and RUBISCO activity to rates equivalent to treatments without exposure to UVR. The turnover of D1 and chlorophyll a (Chl a) remained high during exposure to UVR. Efficiency of energy conversion by photosystem II, measured with double flash (pump and probe) fluorometry, increased by 24% in cells acclimated to UVR. Acclimation to UVR had no detectable effect on the functional absorption cross‐section or cellular concentrations of Chl a, Chl c, or total carotenoids. However, the maximum rate of carbon fixation was reduced by UVR on a Chl a basis but remained unaffected on a per‐cell basis. Response to UVR exposure in this subtropical diatom has two components: a short‐term inhibitory response and a longer‐term acclimation process that ameliorates the inhibition of carbon fixation.
THE EFFECT OF GROWTH TEMPERATURE AND CULTURE DENSITY ON THE MOLECULAR SPECIES COMPOSITION OF THE GALACTOLIPIDS IN THE RED MICROALGA PORPHYHDIUM CRUENTUM (RHODOPHYTA)1
Authors: Adlerstein Daniel , Bigogno Chiara , Khozin Inna , Cohen Zvi
Published: October 2004

The effects of biomass concentration and growth temperature on the molecular species composition of the major galactolipids of the red microalga Porphyridium cruentum Nag. were detmined. At lower biomass concentrations, the Δ17 desaturation of arachidonic acid to eicosapentaenoic acid (20:5) was enhanced in both prokaryotic‐type and eukalyotic‐type molecular species of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol. We suggest that chloroplastic Δ17 desaturation is correlated with the availability of light. A reduction in the growth temperature led to an increase in the proportion of the eukalyotic molecular species of MGDG, especially for 20:5/ 20:5 MGDG, These results suggest that this molecular species, and perhaps eukaryotic molecular species in general, may play a role in the adaptation of cells to low growth temperatures.
AUTOLYSIS KINETICS OF THE MARINE DIATOM DITYLUM BRIGHTWELLII (BACILLARIOPHYCEAE) UNDER NITROGEN AND PHOSPHORUS LIMITATION AND STARVATION1
Authors: Brussaard Corina P. D. , Noordeloos Anna A. M. , Riegman Roel
Published: October 2004

Autolysis kinetics in axenic cultures of the diatom Ditylum brightwellii (West) Grunow were studied under nutrient limitation in continuous cultures and under nutrient starvation in batch‐mode cultures obtained by switching off nutrient supply in the continuous cultures. Under N limitation, the specific algal autolysis rates (δ, day−1) were found constant at 0.014 ± 0.002 day−1over a broad range of specific dilution rates (D, day−1) (0.09–0.56 day−1), implying an intrinsic death factor independent of the physiologzc state of the algal cells. Under P limitation, 8 was inversely related to D and ranged between 0.067 and 0.005 day−1 at D = 0.17–0.44 day−1. Under conditions of nutrient stamation, the degree of algal nutrient deficiency prior to stamation affected autolysis rates (δb, day−1) and subsequently survival of the algal cultures. Nitrogen‐starved D. brightwellii showed highest δb (maximum, 0.10 day−1) when precultured at the higher growth rates. Phosphorus stamation led to highest δb (maximum, 0.21 day−1) in the cultures preconditioned at the lower steady state growth rates. The lower death rates for D. brightwellii under limitation and starvation of N compared to P suggest that D. brightwellii was better equipped to handle N than P deficiency. The present results showed that cell lysis induced by nutrient stress was a significant cause of mortality in D. brightwellii and provided more insight into the field distribution of this neritic diatom.
PHYLOGENYOF THE VLE‐14 CHLAMYOMONAS (CHLOROPHYCEAE) GROUP: A STUDY OF 18S rRNA GENE SEQUENCES1
Authors: Buchheim Mark A. , Buchheim Julie A. , Chapman Russell L.
Published: October 2004

Comparative specificity of sporangial wall autolysins (i.e. vegetative lytic enzymes [VLE]) derived from sporulating cultures has been used to group Chlamydomonas taxa into 15 different VLE types. The VLE‐14 group, including isolates of C. geitleri, C. noctigama, C. monoica, C. pinicola, C. terricoia, and C. hindakii, is one of the largest of these VLE groups. Genetic studies have shown that a number of the VLE‐14 taxa are interfertile, albeit with little or reduced viability of progeny. A reevaluation of the VLE‐14 group suggested that all members should be regarded as distinct isolates of C. noctigama. The present investigation tests the phylogenetic implications of the VLE evidence and examines the validity of the taxonomic reevaluation in a phylogenetic context by analysis of 18S rRNA gene sequence data. Results from analyses of the sequence data are consistent with an interpretation of the VLE evidence as indicative of monophyletic taxa. Phylogenetic analyses of the sequence data are also consistent with the taxonomic reevaluation and reidentification of the group. However, at least some of the VLE‐14 isolates studied in this investigation fit criteria for distinct biologic or phylogenetic species. It is concluded that the VLE‐14 taxa represent a very closely allied group that includes some isolates that are in the early stages of speciation ly reproductive isolation.
A MOLECULAR PHYLOGENY OF THE HETEROKONT ALGAE BASED ON ANALYSES OF CHLOROPLAST‐ENCODED rbcL SEQUENCE DATA1
Authors: Daugbjerg Niels , Andersen Robert A.
Published: October 2004

Nearly complete ribulose‐1,5‐bisphosphate carboxylase/ oxygenase (rbcL)sequences from 27 taxa of heterokont algae were determined and combined with rbcL sequences obtained from GenBank for four other heterokont algae and three red algae. The phylogeny of the morphologically diverse haterokont algae was inferred from an unambiguously aligned data matrix using the red algae as the root, Significantly higher levels of mutational saturation in third codon positions were found when plotting the pair‐wise substitutions with and without corrections for multiple substitutions at the same site for first and second codon positions only and for third positions only. In light of this observation, third codon positions were excluded from phylogenetic analyses. Both weighted‐parsimony and maximum‐likelihood analyses supported with high bootstrap values the monophyly of the nine currently recognized classes of heterokont algae. The Eustigmatophyceae were the most basal group, and the Dictyochophyceae branched off as the second most basal group. The branching pattern for the other classes was well supported in terms of bootstrap values in the weightedparsimony analysis but was weakly supported in the maximum‐likelihood analysis (<50%). In the parsimony analysis, the diatoms formed a sister group to the branch containing the Chrysophyceae and Synurophyceae. This clade, charactetized by siliceous structures (frustules, cysts, scales), was the sister group to the Pelagophyceae/Sarcinochrysidales and Phaeo‐/Xantho‐/ Raphidophyceae clades. In the latter clade, the raphido‐phytes were sister to the Phaeophyceae and Xanthophyceae. A relative rate test revealed that the rbcL gene in the Chrysophyceae and Synurophyceae has experienced a significantly different rate of substitutions compared to other classes of heterokont algae. The branch lengths in the maximum‐likelihood reconstruction suggest that these two classes have evolved at an accelerated rate. Six major carotenoids were analyzed cladistically to study the usefulness of carotenoid pigmentation as a class‐level character in the heterokont algae. In addition, each carotenoid was mapped onto both the rbcL tree and a consensus tree derived from nuclear‐encoded small‐subunit ribosomal DNA (SSU rDNA) sequences. Carotenoid pigmentation does not provide unambiguous phylogenetic information, whether analyzed cladistically by itself or when mapped onto phylogenetic trees based upon molecular sequence data.
RECOGNITION OF TAXONOMICALLY SIGNIFICANT CLUSTERS NEAR THE SPECIES LEVEL, USING COMPUTATIONALLY INTENSE METHODS, WITH EXAMPLES FROM THE STEPHANODISCUS NIAGARAE COMPLEX (BACILLARIOPHYCEAE)1
Authors: Julius Matthew L. , Estabrook George F. , Edlund Mark B. , Stoermer Eugene F.
Published: October 2004

Since the early 1960s, numerical techniques have produced a wide variety of methods to suggest classifications of organisms based on quantitative measurements. A long‐recognized shortcoming of these methods is that they will suggest classifications for any group of organisms and any set of measurements, whether or not the clusters in the suggested classification have any natural meaning or significance. Some progress has been made in assessing the reality of clusters determined by various methods. Data simulated to reflect known cluster structure have been used to test the accuracy of different methods, Various methods have been applied to the same data sets to compare how well they realize various desirable properties. Here we define a data‐based model of randomness to represent what might be meant by “no natural basis for subdivision into clusters” and use it to compare an observed measure of cluster distinctness to the distribution of this measure predicted by this model of randomness. In this way, unwarranted subdivision can be statistically avoided, and significant subdivisions can be investigated with confidence. Our methods are illustrated with some examples from the Stephanodiscus niagarae Ehrenb. species complex. Significant differences in morphologic expression are identified in S. reimerii Theriot and Stoermer in Theriot, S. superiorensis Theriot and Stoermer and S. yellowstonensis Theriot and Stoermer. In addition, statistically significant clusters are identified in S. niagarae populations from different geographic locations and in members of the same population grown in different environments. These results suggest current criteria for resolving diatom taxa may not be sufficient to discern subtle differences that occur between real species.
CHARACTERIZATION AND MOLECULAR PHYLOGENYOF A PROTEIN KINASE cDNA FROM THE DINOFLAGELLATE GONYAULAX (DINOPHYCEAE)1
Authors: Salois Patrick , Morse David
Published: October 2004

Degenerate primers corresponding to conserved protein kinase motifs were used to amplify potential kinase DNA fragments from a Gonyaulax polyedra Stein cDNA library using PCR. One PCR fragment, potentially encoding a CAMP‐dependent protein kinase, was used as a probe to isolate a near full‐length cDNA from the library. The nucleic acid sequence of the entire cDNA clone had a high homology to the catalytic subunit of cAMP‐dependent protein kinase (cAPK subfamily and affiliated members. Northern blot analysis showed that the corresponding mRNA had a size (about 1.4 kb) and a relative high abundance consistent with a cAPK homologue. Southern blot analysis showed that while there are roughly 30 copies of the kinase gene per genome, the pattern of restriction fragments is inconsistent with the hypothesis of a large gene family. Phylogenetic analyses comparing the deduced amino acid sequence from the Gonyaulax cDNA with other cAPK sequences place Gonyaulax close to the slime mold Dictyostelium discoideum. This is the first phylogenetic analysis of dinoflagellates based on protein sequence, and the results are in agreement with similar analyses based on rRNA sequences.
THE USE OF IMMOBILIZATION IN ALGINATE BEADS FOR LONG‐TERM STORAGE OF PSEUDANABAENA GALEATA (CYANOBACTERIA) IN THE LABORATORY1
Authors: Romo Susana , Pérez‐Martínez Carmen
Published: October 2004

A new method for long‐term storage of algal cultures in the laboratory was tested. The procedure is based on the cell immobilization technique. Cells of the filamentous cyanobacterium Pseudanabaena galeata Bocher were immobilized in sodium‐alginate beads and stored for 14–18 months. The structure and functional features of the organism were maintained in this immobilized state and no ultrastructural biochemical, or growth rate differences were detected between stock and previously immobilized cell cultures after this period. We discuss the advantages of this method compared to other preservation methods and recommend the use of immobilization in alginate beads for long‐term algal storage.
Caulerpa taxifoliain the Mediterranean: Damage Control and Opportunities for New Research
Authors: Olsen Jeanine L.
Published: October 2004

Academie des Science—Paris. 1997. Danamique d'especs marines invasives: application a l'expansion de Caulerpa taxifolia en Mediterranee. Technique and Documentation.
IL‐10 is not required to prevent immune hyperactivity during memory responses to Toxoplasma gondii
Authors: Wille U. , Nishi M. , Lieberman L. , Wilson E. H. , Roos D. S. , Hunter C. A.
Published: October 2004

Primary infection of IL‐10 knockout (KO) mice with the protozoan parasite Toxoplasma gondii leads to a CD4+‐T‐cell dependent shock‐like reaction with high systemic levels of IL‐12 and IFN‐γ, severe liver pathology and death of mice. In the present study, this immune‐mediated pathology was prevented by treatment of IL‐10 KO mice with the anti‐parasitic drug sulfadiazine, allowing these mice to progress to the chronic phase of infection. To address the role of endogenous IL‐10 in the regulation of secondary immune responses to T. gondii, IL‐10 KO mice were infected with the avirulent Me49 strain of this parasite, treated with sulfadiazine for 2 weeks starting at day 3 p.i., and were rechallenged 6 weeks p.i. with RH, a highly virulent strain of T. gondii. In these studies, chronically infected IL‐10 KO mice survived secondary infection with RH and controlled parasite load. Although serum levels of IL‐12 and IFN‐γ were higher in IL‐10 KO mice than in wild type (WT) mice 8 days after RH rechallenge, these levels were well controlled in the absence of endogenous IL‐10, suggesting that IL‐10 is not required to down‐regulate cytokine production during the memory response. Antigen‐specific ex vivo recall responses further revealed that splenocytes from chronically infected WT and IL‐10 KO mice responded to parasite antigen with similar production of IL‐12 and IFN‐γ, and there was also no significant difference in ex vivo production of these cytokines by splenocytes in response to parasite antigen 7 days after secondary infection with T. gondii. Furthermore, IL‐10 KO mice immunized with the Ts‐4 vaccine‐strain of T. gondii were protected when rechallenged with the virulent RH strain. Together, these studies demonstrate that the inhibitory effect of IL‐10, which is required to prevent immune‐mediated pathology during primary infection, is not required to prevent immune hyperactivity during a secondary response to T. gondii, and a highly effective memory response is generated in the absence of endogenous IL‐10.
The Folk Psychology of Free Will: Fits and Starts
Authors: Nichols Shaun
Published: October 2004

Abstract: According to agent‐causal accounts of free will, agents have the capacity to cause actions, and for a given action, an agentcould have done otherwise. This paper uses existing results and presents experimental evidence to argue that young children deploy a notion of agent‐causation. If young children do have such a notion, however, it remains quite unclear how they acquire it. Several possible acquisition stories are canvassed, including the possibility that the notion of agent‐causation develops from a prior notion of obligation. Finally, the paper sets out how this work might illuminate the philosophical problem of free will.
Primary sweat gland carcinosarcoma of the scrotal skin
Authors: Lin Tzu‐Ping , Pan Chin‐Chen , Huang William Ji‐Sien , Murphy George F.
Published: October 2004

Background:  Carcinosarcoma is a biphasic tumor composed of malignant epithelial and mesenchymal elements. Although the tumors have been reported in different locations, they rarely occur in the skin and have not been reported in the skin of external genitalia.

Case report:  We present such a case in a 71‐year‐old Taiwanese man. He had had a long‐term indolent nodule on scrotal skin, but it enlarged rapidly in 2 weeks. Wide excision of the tumor was performed.

Results and Discussion:  The pathologic examination revealed a sweat gland carcinosarcoma consisting of admixed mucin‐producing adenocarcinoma and solid spindle cell sarcoma. The two components exhibited contrasting immunohistochemical profiles with the epithelial component diffusely positive for epithelial markers and S‐100 protein, while the sarcomatous component positive for vimentin and smooth muscle actin but negative for epithelial markers and S‐100 protein. The immunoreactivity for S‐100 protein in the epithelial component supports sweat gland origin. The tumor behaved aggressively. Local recurrence and distant metastases to lungs and brain occurred 6 months and 18 months later. The patient died of the disease 20 months after the initial diagnosis.