bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF FLOWING WATER ON NITROGEN‐ AND PHOSPHORUS‐LIMITED PHOTOSYNTHESIS AND OPTIMUM N:P RATIOS BY SPIROGYRA FLUVIATILIS (CHAROPHYCEAE)1,2
Authors: Borchardt Mark A. 
Published: October 2004

ABSTRACTThe effects of flowing water on net photosynthesis, dark respiration, specific growth rate, and optimum N:P ratios by Spirogyra fluviatilis Hilse were assessed. The alga was cultivated under nitrogen or phosphorus limitation in laboratory streams at three flow velocities: 3, 12, and 30 cm·s−1. The Droop equation adequately described respiration and photosynthesis (PSnet) as a function of N or P cell quota (QN or Qp). The data show that for N‐ or P‐limited Spirogyra fluviatilis, flowing water is physiologically costly. Generally, flowing water had little effect on respiration rates; however, the proportion of gross photosynthesis devoted to dark respiration did increase with flow velocity. For photosynthesis, the minimum N and P cell quotas increased with velocity, and the theoretical PSnet maxima for N and P both appeared greatest at 12 cm·s−1. The Droop models showed that for any given QN or Qp, PSnet, was reduced by the 30‐cm·s−1 treatment. Consistent with this finding, independent estimates of specific growth rates for P‐limited S. fluviatilis in the laboratory streams were inversely related to flow velocity when ambient PO4−3 was undetectable. However, growth was not diminished at the fastest velocity when PO4−3 was available for uptake. Thus, the increase in cellular phosphorus demand can be offset by flow‐enhanced P uptake when conditions permit; otherwise, growth will be impaired.The optimum N:P ratios for S. fluviatilis at 3, 12, and 30 cm·s−1 were 50, 58, and 52 by atoms, respectively, when calculated for PSnet= 0. The optimum ratios were inversely related to PSnet and decreased to approximately 20 when PSnet was near maximum. The potential for flowing water to mediate nutrient partitioning among lotic algae by altering growth rates and optimum nutrient ratios is discussed.
METABOLIC ACTIVITY OF MICROORGANISMS IN EVAPORITES1
Authors: Rothschild Lynn J. , Giver Lorraine J. , White Melisa R. , Mancinelli Rocco L. 
Published: October 2004

ABSTRACTCrystalline salt is generally considered so hostile to most forms of life that it has been used for centuries as a preservative. Here, we present evidence that prokaryotes inhabiting a natural evaporite crust of halite and gypsum are metabolically active while inside the evaporite for at least 10 months.In situmeasurements demonstrated that some of these “endoevaporitic” microorganisms (probably the cyanobacteriumSynechococcusNägeli) fixed carbon and nitrogen. Denitrifecation was not observed. Our results quantified the slow microbial activity that can occur in salt crystals. Implications of this study include the possibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.
CELL CYCLE AND ACCUMULATION OF ASTAXANTHIN IN HAEMATOCOCCUS LACUSTRIS (CHLOROPHYTA)1
Authors: Lee Yuan‐Kun , Ding Sun‐Yeun 
Published: October 2004

ABSTRACTSynchronous release of ellipsoidal biflagellated zoo‐spores from thick‐walled akinetes of Haematococcus lacustris (Gir.) Rostaf. (UTEX 16) was induced. After being released, the zoospores divided rapidly at a rate that depended on the initial concentration of urea in the culture medium. Cells fused after approximately five doublings, and the DNA content of most cells doubled within 50 h. Spherical nonmotile palmella cells and aplanospores appeared after 100 h of incubation in media containing high (1.7 g·L−1) and low (0.85 g·L−1) urea concentrations. Thereafter, the number of nonmotile cells increased with time, whereas motile cell numbers decreased with time. Nonmotile cells continued to grow and divide by forming 4–32 aplanospores, for up to 200 h of incubation in the high‐urea medium. The size of the nonmotile cells and the number of daughter cells formed within was inversely proportional to the growth rate of the cultures. Within the first 100 h of incubation, dry weight biomass of the zoo‐spores increased from about 0.3 to 0.8 g·L−1. In the following 180 h, dry weight biomass reached 1.7 g·L−1 in the low‐urea medium and 2.5 g·L−1 in the high‐urea medium. The astaxanthin content of zoospores decreased with time, whereas there was a net accumulation of astaxanthin in the nonmotile cells. The specific rate of accumulation of astaxanthin in motile and nonmotile cells, however, was practically identical.
DETECTION OF PROLIFERATING CELL NUCLEAR ANTIGEN ANALOG IN FOUR SPECIES OF MARINE PHYTOPLANKTON1
Authors: Lin Senjie , Chang Jeng , Carpenter Edward J. 
Published: October 2004

ABSTRACTProliferating cell nuclear antigen (PCNA) is an auxiliary protein for polymerase‐δ and therefore is essential for cellular DNA synthesis. The synthesis and abundance of PCNA in the cell are cell‐cycle‐dependent, both increasing markedly during the S phase. Such a protein could be a useful cell cycle marker, which is required for estimating algal species‐specific growth rates via the cell cycle approach. By using commercially available monoclonal anti‐rat‐PCNA antibody and an enhanced chemiluminescence technique, PCNA‐like proteins were detected in four species of marine phytoplankton. The strong single band detected on western blots of Isochrysis galbana Parke, Thalassiosira weissflogii Cleve, and Dunaliella tertiolecta Butcher had an apparent molecular weight of 33–36 kDa. This molecular weight is within the range as observed for PCNA in a wide phylogenetic array of organisms (33–36 kDa). In the diatom Skeletonema costatum (Grev.) Cleve, the PCNA antibody detected a major band of about 19 kDa as well as a minor band of 38 kDa. The detected proteins were specifically recognized by the monoclonal anti‐rat‐PCNA antibody. The PCNA‐like proteins in I. galbana, T. weissflogii, and D. tertiolecta were more abundant in the exponential growth stage and then decreased and became undetectable in the late stationary stage. Our results show that the detected antigens appear to be algal analogs of PCNA.
SALINITY TOLERANCE, BILIPROTEINS, AND FLORIDOSIDE CONTENT OF COMPSOPOGON COERULEUS (RHODOPHYTA)1
Authors: Glazer Alexander N. , Chan Crystal F. , Karsten Ulf , West John A. 
Published: October 2004

ABSTRACTThe freshwater red alga Compsopogon coeruleus (Balbis) Montague is capable of growing and reproducing in salinities up to 35 ppt. Increased accumulation of floridoside (D‐galactopyranosyl glycerol) parallels increase in salinity. Compsopogon phycobilisomes contain an unusual B‐phycoerythrin completely lacking in phycourobilin chromophores, but with a pigmented γ subunit. The α, β, and γ subunits of this phycoerythrin all carry phycoerythrobilins. These results suggest that C. coeruleus is secondarily adapted to freshwater from marine habitats.
HOST SPECIFICITY IN THE RED ALGAL PARASITES BOSTRYCHIOCOLAX AUSTRALIS AND DAWSONIOCOLAX BOSTRYCHIAE (CHOREOCOLACACEAE, RHODOPHYTA)1
Authors: Zuccarello Giuseppe C. , West John A. 
Published: October 2004

ABSTRACTThe determinants of host specificity, which are poorly understood in red algal parasites, were studied in the red algal parasites Bostrychiocolax australis Zuccarello et West and Dawsoniocolax bostrychiae (Joly et Yamaguishi‐Tomita) Joly et Yamaguishi‐Tomita. Culture studies were performed to determine host range, sites of host resistance, and genetics of transmission of resistance. Both species parasitize Bostrychia radicans (Montagne) Montagne, whereas Bostrychiocolax australis also parasitizes Bostrychia moritziana (Sonder ex Kützing) J. Agardh and Stictosiphonia kelanensis (Grunow ex Post) R. J. King et Puttock. Isolates of B. radicans resistant to both parasites were found worldwide, often within the same population as susceptible isolates. On resistant Bostrychia species and isolates, specificity was manifested at three stages: 1) host penetration, in which the spore germ peg failed to penetrate the host cuticle/wall; 2) parasite–host cell fusion, in which the fusion cell died and the parasite died; and 3) growth, in which parasites grew but soon died; parasites rarely reproduced and infections did not continue in culture. Resistance to parasite infection was usually transmitted as a dominant trait and did not segregate as a single locus during meiosis. In certain crosses, transmission of resistance was non‐mendelian.
18S RIBOSOMAL DNA SEQUENCES INDICATE A MONOPHYLETIC ORIGIN OF CHAROPHYCEAE1
Authors: Ragan Mark A. , Parsons Thomas J. , Sawa Takashi , Straus Neil A. 
Published: October 2004

ABSTRACTNuclear‐encoded small‐subunit (18S) ribosomal RNA genes ofChara australisR. Brown(C. corallinavar.nobilisf.nobilisR.D.W.) andNitella flexilis (L.)Ag. were amplified by polymerase chain reaction, cloned, and completely sequenced. Using structural criteria, the sequences were aligned with 18S ribosomal DNAs (rDNAs) from 11 other chlorophyllb‐containing algae and six higher plants (embryophytes). Phylogenetic trees were inferred by distance, neighbor‐joining, parsimony, and maximum‐likelihood approaches; confidence intervals were estimated by bootstrapping, and nonrandomness of tree structure was confirmed by permutation tests. 18S rDNAs ofC. australisand twoNitellaspecies were found to be specifically related and, together with 18S rDNAs ofChlorokybus atmophyticusGeitler,Klebsormidium flaccidum(A. Br.) Silva, Mattox, et Blackwell, and twoColeochaetespecies, support a robust monophyletic group (Charophyceae). Although most trees favored a specific sister‐group relationship between Charophyceae and embryophytes, statistical tests revealed that a sister‐group relationship between Charophyceae and Chlorophyceae could not be ruled out. Additional complete sequences from 18S rDNAs of lower land plants may be required to resolve phylogenetic relationships among these organisms.
ISOLATION AND CHARACTERIZATION OF PHASE‐SPECIFIC COMPLEMENTARY DNAs FROM SPOROPHYTES AND GAMETOPHYTES OF PORPHYRA PURPUREA (RHODOPHYTA) USING SUBTRACTED COMPLEMENTARY DNA LIBRARIES1
Authors: Liu Qing Yan , van der Meer John P. , Reith Michael E. 
Published: October 2004

ABSTRACTThe red alga Porphyra purpurea (Roth) C. Agardh has a life cycle that alternates between shell‐boring, filamentous sporophytes and free‐living, foliose gametophytes. The significant morphological differences between these two phases suggest that many genes should be developmentally regulated and expressed in a phase‐specific manner. In this study, we prepared and screened subtracted complementary DNA (cDNA) libraries specific for the sporophyte and gametophyte of P. purpurea. This involved the construction of cDNA libraries from each phase, followed by the removal of common clones through subtractive hybridization. Sampling of the subtracted libraries indicated that 8–10% of the recombinant colonies in each library were specific for the appropriate phase. Of 20 putative phase‐specific cDNAs selected from each subtracted library, eight unique clones were obtained for the sporophyte and seven for the gametophyte. After confirming their phase‐specificities by hybridization to gametophyte and sporophyte messenger RNA, these 15 phase‐specific cDNAs were sequenced, and the deduced amino acid sequences were used to search protein databanks. Two proteins encoded by the sporophyte‐specific cDNAs and two by the gametophyte‐specific cDNAs were identified by their similarity to databank entries.
MOLECULAR DELINEATION OF SPECIES AND SPECIES RELATIONSHIPS IN THE RED ALGAL AGAROPHYTES GRACILARIOPSIS AND GRACILARIA (GRACILARIALES)1
Authors: Goff Lynda J. , Moon Debra A. , Coleman Annette W. 
Published: October 2004

ABSTRACTDelineation of species in the economically important agarophyte genera Gracilaria and Gracilariopsis has proven extremely difficult using available morphological characteristics. In this study, we examine the usefulness of two transcribed spacers for molecular systematic studies of these genera. The polymerase chain reaction was used to amplify the internal transcribed spacers (ITSs) and the intervening 5.8S ribosomal DNA of the nuclear ribosomal repeat region. In addition, a plastid spacer region and flanking regions of coding genes were amplified from the RUBISCO operon. Both regions were sequenced for individuals and populations of Gracilariopsis lemaneiformis (Bory) Dawson, Acleto, et Foldvik to determine the usefulness of these spacers in delimiting populations. These studies reveal that there is as much variation among individuals of a population as there is between individuals of geographically separate populations. In addition, the ITS spacer regions were compared between different species of Gracilariopsis and Gracilaria. The nuclear ITS spacer region is conserved at a species level in both genera and provides phylogenetically informative characters that can be used to examine species interrelationships among relatively closely related taxa. However, because of the difficulties of aligning this entire region among species from the two genera, the ITS region is not useful for examining intergenera relationships. ITS interspecies sequence comparisons indicate that Gracilariopsis lemaneiformis from California is significantly different from G. lemaneiformis from China and that a species of Gracilariopsis from Peru is more closely related to G. lemaneiformis from North Carolina than it is to the other Gracilariopsis species examined. In addition, these studies indicate that Gracilaria chilensis Bird, McLachlan, et Oliveira from New Zealand and Gracilaria tenuistipitata Chang et Xia from southeast Asia are as closely related as are Gracilaria verrucosa (Hudson) Papenfuss, G. pacifica Abbott, and Gracilaria robusta Kylin. Phylogenetic analysis of aligned plastid spacer sequences from Gracilaria and Gracilariopsis taxa provide similar conclusions about species relationships.
TETREUTREPTIA POMQUETENSIS GEN. ET SP. NOV. (EUGLENOPHYCEAE): A QUADRIFLAGELLATE, PHOTOTROPHIC MARINE EUGLENOID1
Authors: McLachlan Jack L. , Seguel Miriam R. , Fritz Lawrence 
Published: October 2004

ABSTRACTA new euglenoid genus and species, Tetreutreptia pomquetensis, is described from winter waters of Maritime Canada. This phototrophic species is characterized by four emergent heterodynamic flagella, two about the length of the cell and two less than one‐half this length. Tetreutreptia pomquetensis has features in common with species of Eutreptiella while it differs in several respects from any of the described species of that genus. It could be assigned to the order Eutreptiales or Euglenamorphales sensu Leedale or the order Euglenales sensu Farmer. This new alga has a narrow range of temperature tolerance; it grows best from 0° to 7° C and dies at temperatures above 10° C. The optimum salinity for growth was near full‐strength seawater. Growth conditions for the alga define the conditions whence this species was isolated.
GENETIC VARIABILITY WITHIN A POPULATION AND BETWEEN DIPLOID/HAPLOID TISSUE OF MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1
Authors: Coyer James A. , Robertson Deborah L. , Alberte Randall S. 
Published: October 2004

ABSTRACTMulti‐locus DNA fingerprints using an M13 probe were obtained for eight individuals of giant kelp Macrocystis pyrifera (L.) C. Ag. collected from Monterey Bay, California. For each individual, DNA was extracted from a diploid blade and from ca. 109 haploid spores that were released from four to Jive sporophylls. Viable or swimming spores from one individual were pooled and referred to as a spore group. A total of 34 bands (4–19 kb) was detected in DNA fingerprints from the eight blades and eight spore groups, with individual blade or spore groups exhibiting 7–18 bands (mean = 12.6). One band (4.5 kb) was present in all 16 samples. Eight bands were detected in 11–14 of the 16 samples. Similarity indices were calculated for all pairwise comparisons of fingerprint bands among all possible combinations of blades and spore groups. Mean similarity indices for the eight blades (0.51, SE = 0.032) and spore groups (0.56, SE = 0.031) were significantly lower than for the eight comparisons of the blade and spore groups from a single individual (0.86, SE = 0.052). The data indicate that DNA fingerprints can be used to measure genetic variation within populations of M. pyrifera because variation of DNA fingerprints associated with meiotic products (spores) of a given individual is small relative to variation observed among individuals within the population. Additionally, fingerprint variation between diploid vegetative tissue and haploid meiotic products may be a measure of genetic change due to recombination or DNA turnover mechanisms.
QUANTITATIVE GENETICS OF FATTY ACID VARIATION IN ISOCHRYSIS GALBANA (PRYMNESIOPHYCEAE) AND PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE)1
Authors: Alonso Diego López , del Castillo Clara I. Segura , Sánchez José L. García , Sánchez Pérez José A. , Camacho Francisco Garcia 
Published: October 2004

ABSTRACTFatty acid variation among culture collection strains and 40 new isolates of Isochrysis galbana Parke was analyzed by quantitative genetic methods. Fatty acid variation among strains and among isolates was highly significant for major fatty acids showing the existence of a genetic component in the determination of differences in fatty acid content. The heritabilities for the major fatty acids ranged between 0.68 and 0.99 among collection strains and between 0.31 and 0.43 among isolates. Eicosapentaenoic acid (EPA) had the highest heritability in I. galbana, but the majority of remaining fatty acids also showed high heritability values. A similar experiment with five UTEX strains of Phaeodactylum tricornutum also showed the presence of a genetic component in four out of seven major fatty acids. Nevertheless, the UTEX strains did not differ significantly in EPA content, although they showed a heritability of 0.40 for this fatty acid. An additional experiment culturing the same isolates of I. galbana in larger volumes of media showed that there was a high significant positive linear relation between EPA content in different volumes. Therefore, EPA content in small volume cultures was an unbiased indicator of EPA content in larger volume cultures. Our results provide support for the genetic determination of fatty acid content in microalgae and suggest that selection, and mutation and selection, are likely to improve EPA content in I. galbana and probably in many other microalgae. Such a selection program can be carried out in small‐volume cultures with high confidence.
CRYOPRESERVATION OF THE CONCHOCELIS OF PORPHYRA (RHODOPHYTA) BY APPLYING A SIMPLE PREFREEZING SYSTEM1
Authors: Kuwano Kazuyoshi , Aruga Yusho , Saga Naotsune 
Published: October 2004

ABSTRACTThe conchocelis cells of four strains of Porphyra yezoensis Udea and four other Porphyra species were cryopreserved in liquid nitrogen (LN) using a programmable freezer or a simple prefreezing system, which consisted of a styrofoam box and a deep‐freezer at −40° C. The cells differed in their freezing tolerance but survived maximally when prefrozen to −40° C in a cryoprotective solution composed of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater. The cryopreservation was successfully performed by applying the simple prefreezing system as well as by a programmable freezer. Conchocelis cells thawed from the LN temperature formed colonies and retained the ability to form conchospores that grew into gametophytic thalli. This technique using a simple prefreezing system will accelerate the spread of Porphyra cryopreservation.
GROWTH OF THE FILAMENTOUS GREEN ALGA CTENOCLADUS CIRCINNATUS (CHAETOPHORALES, CHLOROPHYCEAE) IN RELATION TO ENVIRONMENTAL SALINITY1
Authors: Herbst David B. , Castenholz Richard W. 
Published: October 2004

ABSTRACTClones of the filamentous green alga Ctenocladus circinnatus Borzi were isolated from algae collected at Abert Lake (Oregon) and Mono Lake (California). Stock cultures were exposed to varied salinities of natural lake water to examine the effects on growth rate, cell form, chlorophyll a, and water content. Growth rates were reduced in both clones with increased salinity over the range 25–100 g·L−1 and were almost completely inhibited at 150 g·L−1. Chlorophyll a increased between salinities of 25 and 100 g·L−1, reflecting slower growth, higher proportions of akinetes, and smaller cell sizes as salinity increased. Tissue water content remained essentially constant from 25 to 100 g·L−1 salinity. Shorter cell dimensions with increased salinity suggest that a lower surface‐to‐volume ratio may reduce the potential for passive loss of cell water. Prior acclimation of stock cultures to elevated salinity provided no enhancement of growth response at any salinity. The results indicate that environmental salinity can limit the productivity and distribution of Ctenocladus in nature.
RADIOLABELING STUDIES OF LIPIDS AND FATTY ACIDS IN NANNOCHLOROPSIS (EUSTIGMATOPHYCEAE), AN OLEAGINOUS MARINE ALGA1
Authors: Schneider Jane C. , Roessler Paul 
Published: October 2004

ABSTRACTThe synthesis of fatty acids and lipids in Nannochloropsis sp. was investigated by labeling cells in vivo with [14C]‐bicarbonate or [14C]‐acetate. [14C]‐bicarbonate was incorporated to the greatest extent into 16:0, 16:1, and 14:0 fatty acids, which are the predominant fatty acids of triacylglycerols. However, more than half of the [14C]‐acetate was incorporated into longer and more desaturated fatty acids, which are constituents of membrane lipids. [14C]‐acetate was incorporated most strongly into phosphatidylcholine, which rapidly lost label during a 5‐h chase period. The label associated with phosphatidylethanolamine also decreased during the chase period, whereas label in other membrane lipids and triacylglycerol increased. The dynamics of labeling, along with information regarding the acyl compositions of various lipids, suggests that 1) the primary products of chloroplast fatty acid synthesis are 14:0, 16:0, and 16:1; 2) C20 fatty acids are formed by an elongation reaction that can utilize externally supplied acetate; 3) phosphatidylcholine is a site for desaturation of C18 fatty acids; and 4) phosphatidylethanolamine may be a site for desaturation of C20 fatty acids.