bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHYLOGENETIC ANALYSIS OF EUDORINA SPECIES (VOLVOCACEAE, CHLOROPHYTA) BASED ON rbcL GENE SEQUENCES1
Authors: Nozaki Hisayoshi , Ito Motomi , Uchida Hidenobu , Watanabe Makoto M. , Kuroiwa Tsuneyoshi 
Published: October 2004

ABSTRACTSpecies and varieties in the genus Eudorina Ehrenberg (Volvocaceae, Chlorophyta) were evaluated on the basis of phylogenetic analyses of the large subunit ofribulose‐1,5‐bis‐phosphate carboxylase/oxygenase (rbcL) gene sequences from 14 strains of four Eudorina species, as well as from nine species of Pleodorina and Volvox. The sequence data suggested that 10 of the 14 Eudorina strains form three separate and robust monophyletic groups within the nonmonophyletic genus Eudorina. The first group comprises all three strains of E. unicocca G. M. Smith; the second group consists of one of the E. elegans Ehrenberg var. elegans strains, the E. cylindrica Korshikov strain, and both E. illinoisensis (Kofoid) Pascher strains; and the third group consists of two monoecious varieties of E. elegans [two strains of E. elegans var. synoica Goldstein and one strain of E. elegans var. carteri (G. M. Smith) Goldstein]. In addition, E. illinoisensis represents a poly‐ or paraphyletic species within the second group. The remaining four strains, all of which are assigned to E. elegans var. elegans, are nonmonophyletic. Although their position in the phylogenetic trees is more or less ambiguous, they are ancestral to other taxa in the large anisogamous/oogamous monophyletic group including Eudorina, Pleodorina, and Volvox (except for sect. Volvox). Thus, the four Eudorina groups resolved in the present molecular phylogeny do not correspond with the species concepts of Eudorina based on vegetative morphology, but they do reflect the results of the previous intercrossing experiments and modes of monoecious and dioecious sexual reproduction.
THE NATURAL LIFE CYCLE IN WILD POPULATIONS OFDIATOMA MONILIFORMIS(BACILLARIOPHYCEAE) AND ITS DISRUPTION IN AN ABERRANT ENVIRONMENT1
Authors: Potapova Marina , Snoeijs Pauli 
Published: October 2004

ABSTRACTWe studied how size variation in populations ofDiatoma moniliformisKütz. was influenced by environmental effects on the diatom life cycle. One of the two populations sampled monthly in the northern Baltic Sea grew under natural conditions; the other population was in a cooling water discharge channel of a nuclear power plant, where the temperature and flow rate of the water were artificially higher. The life cycle was synchronous at the natural site, with sexual reproduction occurring in the winter; most of the initial cells were found in March‐April. After this, a reduction in cell size occurred, and the vegetative life cycle consisted of two parts. During the first part, cell volume decreased, whereas the surface area to volume ratio increased, and during the second part of the cycle, both of these parameters decreased. No direct evidence was found for the existence of a supra‐annual life cycle inD. moniliformis,as convincing modes fm large cells were lacking in the size‐frequency distributions. It was concluded from extrapolations of the data that the natural life cycle ofD. moniliformisprobably lasts 2 or 3 years. The changes in cell proportions during the life cycle fit well with annual growth cycles ofD. moniliformisat the natural site (i.e. the cells had high surface area to volume ratios during the period of optimal growth in late spring [May‐June]). At the site affected by cooling water discharge, the synchronization of the natural life cycle was disrupted, but some seasonal size variation did occur. Under natural conditions, auxosporulation is probably triggered by a combination of small cell size, low water temperature (0–3° C), and rapidly increasing light intensity or daylength in late winter to early spring. When these conditions were not met (e.g. at the heated site, the required low temperature was absent), auxosporulation did not occur simultaneously. This paper also presents scanning electron photomicrographs showing the typical shape and fine structure of the initial cell ofD. moniliformis.These cells are semispherical in cross section, possess a pronounced curvature along the longitudinal axis, and are bent in the perualvar plane.
FINE STRUCTURE OF THE MALE AND FEMALE GAMETES OFATRACTOMORPHA PORCATA(SPHAEROPLEACFAE, CHLOROPHYTA) WITH EMPHASIS ON THE DEVELOPMENT AND ABSOLUTE CONFIGURATION OF THE FLAGELLAR APPARATUS1
Authors: Cáceres Eduardo J. , Hoffman Larry R. , Leonardi Patricia I. 
Published: October 2004

ABSTRACTGametogenesis in Atractomorpha porcata Hoffman was initiated b the synchronous mitotic division of nuclei within a multinucleate gametangium. Uninucleate gametes were subsequently produced following two series of cytokinetic divisions. The first series involved the formation of phycoplast microtubules (phycoplastic cytokinesis), whereas the second series did not (nonphycoplastic cytokinesis). Centrioles were connected by a rudimentary striated distal fiber by the time they migrated to the planes of division preceding the first series of cytokinetic division. These first divisions produced binucleate gametocytes. A well‐developed flagellar apparatus lay near the cell surface in close proximity to each nucleus of the gametocyte prior to the second series of cytokinetic divisions that produced the uninucleate gametes. As seen in apical view, the paired basal bodies were directly opposed, with no lateral displacement of their longitudinal axes. In lateral view, the paired basal bodies diverged from one another at an angle of 130–180° (female) or 170–180° (male) and were connected by an arched, distal striated fiber about 670–750 nm long and 600 nm at its widest part. Four electron‐opaque, pyramid‐shaped lateral bodies flanked the basal bodies in close contact with their undersurfaces. The flagellar roots demonstrated a cruciate arrangement, with s=6–9 over 1 (female gametes) or 7–10 over 1 (male gametes) microtubules and d= 2 microtubules. In male gametes, one of the multistranded roots was located close to the eyespot, and a second system of cytoskeletal microtubules was detected internally. Based on gamete ultrastructure, Atractomorpha porcata appears to be the most undifferentiated member of the genus.
UPTAKE, EFFLUX, AND PHOTOSYNTHETIC UTILIZATION OF INORGANIC CARBON BY THE MARINE EUSTIGMATOPHYTE NANNOCHLOROPSIS SP.1
Authors: Sukenik Assaf , Tchernov Dan , Kaplan Aaron , Huertas Emma , Lubian Luis M. , Livne Alexander 
Published: October 2004

ABSTRACTUptake, efflux and utilization of inorganic carbon were investigated in the marine eustigmatophyte Nannochloropsis sp. grown under an air level of CO2. Maximal photosynthetic rate was hardly affected by raising the pH porn 5.0 to 9.0. The apparent photosynthetic affinity for dissolved inorganic carbon (DIC) was 35 μM DIC between pH 6.5 to 9.0, but increased approximately threefold at pH 5.0 suggesting that HCO3‐ was the main DIC species used from the medium. No external carbonic anhydrase (CA) activity could be detected by the pH drift method. However, application of ethoxyzolamide (an inhibitor of CA) resulted an a significant inhibition of photosynthetic O2 evolution and carbon utilization, suggesting involvement of internal CA or CA‐like activity in DIC utilization. Under high light conditions, the rate of HCO3− uptake and its internal conversion to CO2 apparently exceeded the rate of carbon fixation, resulting in a large leak of CO2 from the cells to the external medium. When the cells were exposed to low DIC concentrations, the ratio of internal to external DIC concentration was about eight. On the other hand, in the presence of 2 mM DIC, conditions prevailing in the marine environment, the internal concentration of DIC was only 50% higher than the external one.
VARIATION IN THE OCCURRENCE OF EXTERNAL CARBONIC ANHYDRASE AMONG STRAINS OF THE MARINE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE)1
Authors: John‐McKay Meryl E. , Colman Brian 
Published: October 2004

ABSTRACTEleven different strains of Phaeodactylum tricornutum Bohlin were obtained from three culture collections and were examined for the presence of external and internal carbonic anhydrase (CA). Cells of all strains, grown in standing culture at alkaline pH and low, dissolved inorganic carbon had internal CA, but only eight were found to have external CA. External CA activity was reduced when cultures were bubbled with air and was completely repressed when they were grown on 5% CO2. Expression of external CA activity appears to be regulated by CO2 concentration in the growth medium, but within one species, there appears to be a variation in occurrence of external CA and consequently in the mode of inorganic carbon acquisition.
KINETICS OF CELL DEATH IN THE CYANOBACTERIUM ANABAENA FLOS‐AQUAE AND THE PRODUCTION OF DISSOLVED ORGANIC CARBON1
Authors: Lee Dae‐Young , Rhee G‐Yull 
Published: October 2004

ABSTRACTKinetics of cell death and the production of dissolved organic carbon (DOC) were investigated in Anabaena flos‐aquae (Lyngb.) Bréb grown on three different N sources (N2nitrate, and ammonium) in a phosphorus (P)‐limited chemostat. The fraction of live cells in the total population increased as growth rate increased with decreasing P limitation. Cell death was less in nitrate and ammonium media than in N2. The specific death rate (γ), when calculated as the slope ofv−1x vs. D−1, where vxand D are live cell fraction (or cell viability) and dilution rate, respectively, was 0. 0082 day−1 in N2and 0.0042 day−1 in nitrate. The slope of the plot in ammonium culture was not significant; however, the value of the live cell fraction was within the range for the NO−3culture. The fraction of live vegetative cells in N2 culture was constant at all growth rates and the increase in the overall live cell fraction with growth rate was due entirely to an increase in live heterocysts. Live heterocysts comprised 3.5% of the total cells at a growth rate of 0.25 day−1 and increased to 6.3% at 0.75 day−1 with the ratio of live heterocysts to live vegetative cells linearly increasing with growth rate. The fraction of live vegetative cells was invariant in nitrate cultures us in N2cultures. The live heterocysts fraction also increased with growth rate in nitrate cultures, along with the live heterocysts : live vegetative cells ratio, but the level was lower than in N2cultures. DOC released from dead cells increased inversely with growth rate in N2from 36.4% of the total DOC at a growth rate of 0.75 day−1 to 54.15% at 0.25 day−1. The contribution of cell death to the total DOC production in nitrate and ammonium media was significantly less than that under N2DOC from dead cells consisted mainly of high‐molecular‐weight compounds, whereas DOC excreted from live cells was largely of low molecular weight.
A NEW METHOD FOR ESTIMATING EXTERNAL, CARBONIC ANHYDRASE ACTMTY IN MACROALGAE1,2
Authors: Mercado Jesús M. , Figueroa F. L. , Xauier Niell F. , Axelsson Lennart 
Published: October 2004

ABSTRACTThe effects of external carbonic anhydrase (CA, E.C. 4.2.1.1) on HCO−3and CO2use under disequilibnum conditions were examined in 14 species of macroalgae. CO2 was added to the algae in synthetic seawater free from inorganic carbon and buffered to pH 8.7. This resulted in a transient O2 evolution, which was similar for most of the species tested: an initial rapid increase in the rate was followed by a gradual decrease, approaching a steady state within 10 min. The initial high rate of O2evolution was attributed to diffusive entry of CO2into the cells and the steady state to use of HCO−3. An enhancement of CO2diffusive entry was obtained with acetazolamide, an inhibitor of external CA activity. Using this enhancement, a variable was developed to quantify the degree to which CO2entry into the cell was prevented by the external CA. This variable, CA (%), was used as a measure of the external CA activity of the alga. Comparative measurements of the external CA activity using a potentiomtric method revealed that the new method was able to detect low levels of external CA activity, where the potentiometric method failed. These two different methods could be used together to increase the reliability of the measurements. The new method was useful for red and brown macroalgae and for those green macroalgae that lacked direct HCO3uptake. Thus prominent external CA activity was found for Valonia utricularis (green), Halopteris scoparia (brown), and Osmunda pinnatifida (red), where the potentiometric method failed, or nearly failed, to indicate any external CA activity. Direct uptake of HCO−3interfered with the new method and the degree of this interference was dependent on the magnitude of the uptake.
INTER‐ AND INTRASPECIFIC GENETIC VARIATION IN TWELVE PRYMAESIUM (HAPTOPHYCEAE) CLONES1
Authors: Larsen Aud , Medlin Linda K. 
Published: October 2004

ABSTRACTThe haptophytes Prymnesium parvum Carter and Prymnesium patelliferum Green, Hibberd, and Pienaar are two closely related species, which can only be distinguished by minor differences in the morphology of their organic body scales. The two Prymnesium species are reported to coexist at several locations, including the Sands‐fjord system in southwestern Norway. Comparisons of physiology and toxicity within the two species have failed to reveal differences that can add to the small morphological distinctions used to separate them. To investigate the genetic relationship between the two species, we compared the sequence of the first internal transcribed spacer region (ITS1)and length variation in one intron separating calmodulin genes for four P. parvum strains and eight P. patelliferum strains. Both the ITS1 sequence and the banding patterns obtained by PCR amplification of one intron in the calmodulin genes indicated that the Prymnesium isolates are related by their geographic origin instead of 4 their species affiliation. The results indicate that P. parvum and P. patelliferum are so closely related that they could be considered one species. Alternatively, we discuss the possibility that the two species might be joined in a heteromorphic haploid‐diploid life cycle, as is now widely reported for other haptophycean algae.
UNUSUAL DIHYDROXYSTEROLS AS CHEMOTAXONOMIC MARKERS FOR MICROALGAE FROM THE ORDER PAVLOVALES (HAPTOPHYCEAE)1
Authors: Volkman John K. , Farmen Christine L. , Barrett Stephanie M. , Sikes Elisabeth L. 
Published: October 2004

ABSTRACTRecent studies have led to the identification of an unusual class of dihydroxysterols (steroidal diols termed “pavlovols”)in a few species of microalgae from the genus Pavlova (family Pavlovaceae, class Haptophyceae = Prymnesiophyceae). These compounds have an additional hydroxyl group at G‐4 in the sterol A ring, which appears to be very rare in sterol biosynthetic pathways. The sterol compositions of many other haptophytes from different orders have been analyzed, but to date all have lacked pavlovols. We now report the occurrence of these compounds inDiacronema vlkianumPrauser and two strains ofPavlova pinguisGreen. This is the first report of the lipid composition of these species. Both microalgae contained “24‐methylpavlovol” (4α, 24‐dimethyl‐5α‐cholestan‐3β, 4β‐diol), P. pinguis also contained “24‐ethylpavlovol” (4α‐methyl‐24‐ethyl‐5α‐cholestan‐3β, 4β‐diol), andD. vlkianumcontained a diol identified from its mass spectrum as 4α, 24β‐dimethyl‐5α‐cholest‐22E‐en‐3β,4β‐diol. Both species contained structurally analogous 4‐desmethyl sterols and 4‐methyl sterols, although there were major differences in the proportions in each series. The major 4‐desmethyl sterol in both species was 24‐ethylcholesta‐5, 22E‐dien‐3β‐ol and the major 4‐methyl sterol was 4α‐methyl‐24‐ethyl‐5α‐cholest‐22E‐en‐3β‐ol. The presence of pavlovols inP. pinguis,combined with earlier data, suggests that allPavlovaspecies might have this distinguishing lipid feature. However, their identtjication inD. vlkianumextends the occurrence of these compounds to another genus and shows that they are not unique to the genusPavlova.However, they are probably restricted to species from the order Pavlov ales. The modes of biosynthesis and functions of pavlovols remain unknown.
DESCRIPTION AND CHARACTERIZATION OF THE ALGAL SPECIES AUREOUMBRA LAGUNENSIS GEN. ET SP. NOV. AND REFERRAL OF AUREOUMBRA AND AUREOCOCCUS TO THE PELAGOPHYCEAE1
Authors: DeYoe Hudson R. , Stockwell Dean A. , Biolagare Robert R. , Latasa Mikel , Johnson Paul W. , Hargraves Paul E. , Suttle Curtis A. 
Published: October 2004

ABSTRACTThe Texas brown tide alga (strain TBA‐2) is described as Aureoumbra lagunensis Stockwell, DeYoe, Hargraves, et Johnson, gen. et sp. nov. Pigment composition, chloroplast structure, and 18s ribosomal RNA gene sequence data indicate that A. lagunensis and the east coast brown tide alga Aureococcus anophagefferens (originally placed in the Chrysophyceae) belong in the class Pelagophyceae. The new genus Aureoumbra with A. lagunensis as the type species differs from Aureococcus in 18s ribosomal RNA gene sequence, pyrenoid form, nitrogen physiology, and possession of basal bodies. The genus Aureococcus is placed in the order Pelagomonadates and family Pelagomonadaceae while ordinal placement of Aureoumbra is deferred.
A PRELIMINARY COMPARISON OF RESTRICTION FRAGMENT PATTERNS IN THE GENUS CAULERPA (CHLOROPHYTA) AND THE UNIQUE STRUCTURE OF THE CHLOROPLAST GENOME OF CAULERPA SERTULARIOIDES1
Authors: Lehman Roy L. , Manhart James R 
Published: October 2004

ABSTRACTComparisons of chloroplast DNA restriction fragments in four species of Caulerpa revealed that patterns between the species were different, with few and possibly no homologous bands. Two forms of Caulerpa sertularioides also revealed different patterns, and it is possible that the forms are separate species. The chloroplast genome in Caulerpa sertularioides f sertularioides (S. G. Gmelin) Howe is 131.4 kb in size and lacks large repeat units. The discovery of another green‐algal chloroplast genome that lacks an inverted repeat indicates that this feature is either not ancestral to the Chlorophyceae or has been lost several times. Several gene clusters commonly found in chloroplast DNAs were found to occur in Caulerpa chloroplast DNA, for example, psbD/C, atpF/H, and psaA/B. The 16S and 23s rRNA, which are typically adjacent, contained in an inverted repeat, and cotranscribed, are over 40 kb apart. Genes rps12 and tufA, members of the str operon in eubacteria, are over 50 kb in distance from each other in Caulerpa. The gene order in Caulerpa is unlike any other chloroplast genome characterized to date.
Serum levels of soluble urokinase plasminogen activator receptor is associated with parasitemia in children with acute Plasmodium falciparum malaria infection
Authors: Perch M. , Kofoed PE. , Fischer T. K. , Có F. , Rombo L. , Aaby P. , Eugen‐Olsen J. 
Published: October 2004

SUMMARY Serum levels of soluble urokinase plasminogen activator receptor (suPAR) are significantly elevated and of prognostic value in patients suffering from serious infectious diseases such as HIV and tuberculosis. Our objective was to investigate suPAR levels during symptomatic malaria infection and 7 days after treatment. Children younger than 6 years who presented with fever or other symptoms compatible with malaria were enrolled. Blood films and samples were collected on day 0 and day 7. Twenty‐five children were allocated to each of three groups according to the amount of Plasmodium falciparum detected in their initial blood film. Children in group 1 had parasite densities in excess of 20 parasites per 200 leucocytes. The median plasma suPAR level was 6·49 ng/mL (interquartile range [IQR]: 4·90–7·61) and correlated to parasitemia (Spearman 0·43, P < 0·0001). Blood was obtained from 20 children in group 1 after 7 days of treatment. All became malaria negative in their blood slides and all decreased in suPAR level to median 3·48 ng/mL (IQR: 3·08–3·91) (P < 0·0001). Group 2 consisted of 25 children with 1–20 parasites in their blood slide. The suPAR level was median 2·91 ng/mL (IQR: 2·27–4·40) and decreased with median 0·5 ng/mL following treatment (P = 0·0002). Group 3 showed to be negative in their blood slides and most received antibiotic treatment. suPAR decreased from median 3·26 ng/mL (IQR: 2·77–4·46) to median 2·47 ng/mL (IQR: 2·01–3·75), on day 7 (P = 0·006). This study demonstrates an important association between suPAR and acute malaria infection in humans.
Activation by malaria antigens renders mononuclear cells susceptible to HIV infection and re‐activates replication of endogenous HIV in cells from HIV‐infected adults
Authors: Froebel K. , Howard W. , Schafer J. R. , Howie F. , Whitworth J. , Kaleebu P. , Brown A. L. , Riley E. 
Published: October 2004

SUMMARY We have tested the hypothesis that activation of T cells by exposure to malaria antigens facilitates both de novo HIV infection and viral reactivation and replication. PBMC from malaria‐naïve HIV‐uninfected European donors could be productively infected with HIV following in vitro stimulation with a lysate of Plasmodium falciparum schizonts and PBMC from malaria‐naïve and malaria‐exposed (semi‐immune) HIV‐positive adults were induced to produce higher levels of virus after stimulation with the same malaria extract. These findings suggest that effective malaria control measures might con‐tribute to reducing the spread of HIV and extending the life span of HIV‐infected individuals living in malaria endemic areas.
A protective merozoite protein of Plasmodium falciparum shares an epitope with surface antigens of Paramecium
Authors: Sehgal A. , Singh N. J. , Chakraborty T. , Sharma S. 
Published: October 2004

SUMMARY A Plasmodium falciparum cDNA expression clone, λPf9, had been identified earlier as a protective epitope, using anti‐λPf9 antibodies and combinatorial phagotopes. A segment of the Pf9 gene showed homology with Paramecium immobilization surface antigens such as 51B, 51A and 156G. A synthetic Pf9‐peptide was designed from this region, and specific antibodies were raised. Each of these anti‐Pf9 antibodies and combinatorial reagents, as well as anti‐Paramecium 51B antibodies, recognized the Pf9‐peptide on ELISA, and the same protein band in parasite immunoblots. The P. falciparum protein was released from the merozoite membrane fraction on treatment with PI‐PLC, indicating the presence of a GPI anchor. Anti‐Pf9‐peptide antibodies specifically inhibited the growth of P. falciparum in culture. Immunofluorescence assays showed the reactivity of anti‐Pf9‐peptide sera with P. falciparum merozoites and gametocytes, as well as on the surface of Paramecium tetraurelia. The Pf9‐peptide was able to induce proliferation of splenic lymphocytes obtained from mice infected with the rodent malarial parasites Plasmodium berghei and Plasmodium yoelii. These results point towards Plasmodium Pf9 as a conserved novel protective protein, sharing an epitope with Paramecium surface antigens.