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1

Green Algae  

NSDL National Science Digital Library

Color photomicrographs of several species of green algae with brief descriptions of their chief characteristics and habitat. Scroll to the bottom of the page to links to bacteria, and more protists including diatoms, desmids and rotifers.

Wim van Egmond

2010-01-01

2

Hydrogen production by photosynthetic green algae.  

PubMed

Oxygenic photosynthetic organisms such as cyanobacteria, green algae and diatoms are capable of absorbing light and storing up to 10-13% of its energy into the H-H bond of hydrogen gas. This process, which takes advantage of the photosynthetic apparatus of these organisms to convert sunlight into chemical energy, could conceivably be harnessed for production of significant amounts of energy from a renewable resource, water. The harnessed energy could then be coupled to a fuel cell for electricity generation and recycling of water molecules. In this review, current biochemical understanding of this reaction in green algae, and some of the major challenges facing the development of future commercial algal photobiological systems for H2 production have been discussed. PMID:17133763

Ghirardi, Maria L

2006-08-01

3

Diatoms  

USGS Multimedia Gallery

Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health....

4

Red and Green Algal Origin of Diatom Membrane Transporters: Insights into Environmental Adaptation and Cell Evolution  

PubMed Central

Membrane transporters (MTs) facilitate the movement of molecules between cellular compartments. The evolutionary history of these key components of eukaryote genomes remains unclear. Many photosynthetic microbial eukaryotes (e.g., diatoms, haptophytes, and dinoflagellates) appear to have undergone serial endosymbiosis and thereby recruited foreign genes through endosymbiotic/horizontal gene transfer (E/HGT). Here we used the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum as models to examine the evolutionary origin of MTs in this important group of marine primary producers. Using phylogenomics, we used 1,014 diatom MTs as query against a broadly sampled protein sequence database that includes novel genome data from the mesophilic red algae Porphyridium cruentum and Calliarthron tuberculosum, and the stramenopile Ectocarpus siliculosus. Our conservative approach resulted in 879 maximum likelihood trees of which 399 genes show a non-lineal history between diatoms and other eukaryotes and prokaryotes (at the bootstrap value ?70%). Of the eukaryote-derived MTs, 172 (ca. 25% of 697 examined phylogenies) have members of both red/green algae as sister groups, with 103 putatively arising from green algae, 19 from red algae, and 50 have an unresolved affiliation to red and/or green algae. We used topology tests to analyze the most convincing cases of non-lineal gene history in which red and/or green algae were nested within stramenopiles. This analysis showed that ca. 6% of all trees (our most conservative estimate) support an algal origin of MTs in stramenopiles with the majority derived from green algae. Our findings demonstrate the complex evolutionary history of photosynthetic eukaryotes and indicate a reticulate origin of MT genes in diatoms. We postulate that the algal-derived MTs acquired via E/HGT provided diatoms and other related microbial eukaryotes the ability to persist under conditions of fluctuating ocean chemistry, likely contributing to their great success in marine environments. PMID:22195008

Chan, Cheong Xin; Reyes-Prieto, Adrian; Bhattacharya, Debashish

2011-01-01

5

Introduction to the Green Algae  

NSDL National Science Digital Library

This interesting site on "Green Algae" (a paraphyletic group excluding Plantae) is maintained by the University of California's Museum of Paleontology, and is a central resource for algal information with links to associated resources. Four sections make up the heart of the site: Fossil Record, Life History & Ecology, Systematics, and More on Morphology. Additionally, this well-designed site contains many links to illustrated definitions and additional facts.

Speer, Brian R.

6

Diatoms  

USGS Multimedia Gallery

Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. Diatoms can live in permanently ice-cove...

7

Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength  

E-print Network

Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness algae that is mainly composed of amorphous silica, which features a hierarchical structure that ranges in diatom algae as a basis to study a bioinspired nanoporous material implemented in crystalline silica. We

Buehler, Markus J.

8

How-to-Do-It: Diatoms: The Ignored Alga in High School Biology.  

ERIC Educational Resources Information Center

Provides historical background, descriptions, uses and basis for identification of diatoms. Explains collection, dry-mount cleaning, and preparation procedures of the algae. Cites additional resources. (RT)

Hungerford, James J.

1988-01-01

9

Hierarchical and size dependent mechanical properties of silica and silicon nanostructures inspired by diatom algae  

E-print Network

Biology implements fundamental principles that allow for attractive mechanical properties, as observed in biomineralized structures. For example, diatom algae contain nanoporous hierarchical silicified shells that provide ...

García, Andre Phillipé

2010-01-01

10

Diatoms  

USGS Multimedia Gallery

Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. A scanning electron micrograph (SEM) sho...

11

Diatoms  

USGS Multimedia Gallery

Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. Shown here is a live cell of Didymosphen...

12

Diatoms  

USGS Multimedia Gallery

Diatoms are algae that reflect the biotic condition of streams, lakes and estuaries. Diatoms are important indicator organisms because they are sensitive to natural and human impacts, and monitoring their condition provides information about ecosystem health. A large, living Pleurosira laevis cell h...

13

PPR proteins of green algae  

PubMed Central

Using the repeat finding algorithm FT-Rep, we have identified 154 pentatricopeptide repeat (PPR) proteins in nine fully sequenced genomes from green algae (with a total of 1201 repeats) and grouped them in 47 orthologous groups. All data are available in a database, PPRdb, accessible online at http://giavap-genomes.ibpc.fr/ppr. Based on phylogenetic trees generated from the repeats, we propose evolutionary scenarios for PPR proteins. Two PPRs are clearly conserved in the entire green lineage: MRL1 is a stabilization factor for the rbcL mRNA, while HCF152 binds in plants to the psbH-petB intergenic region. MCA1 (the stabilization factor for petA) and PPR7 (a short PPR also acting on chloroplast mRNAs) are conserved across the entire Chlorophyta. The other PPRs are clade-specific, with evidence for gene losses, duplications, and horizontal transfer. In some PPR proteins, an additional domain found at the C terminus provides clues as to possible functions. PPR19 and PPR26 possess a methyltransferase_4 domain suggesting involvement in RNA guanosine methylation. PPR18 contains a C-terminal CBS domain, similar to the CBSPPR1 protein found in nucleoids. PPR16, PPR29, PPR37, and PPR38 harbor a SmR (MutS-related) domain similar to that found in land plants pTAC2, GUN1, and SVR7. The PPR-cyclins PPR3, PPR4, and PPR6, in addition, contain a cyclin domain C-terminal to their SmR domain. PPR31 is an unusual PPR-cyclin containing at its N terminus an OctotricoPeptide Repeat (OPR) and a RAP domain. We consider the possibility that PPR proteins with a SmR domain can introduce single-stranded nicks in the plastid chromosome. PMID:24021981

Tourasse, Nicolas J; Choquet, Yves; Vallon, Olivier

2013-01-01

14

Intracellular invasion of green algae in a salamander host  

E-print Network

Intracellular invasion of green algae in a salamander host Ryan Kerneya,1 , Eunsoo Kimb , Roger P) and green algae ("Oophila amblystomatis" Lamber ex Printz) has been considered an ectosymbiotic mutu- alism tracts, consistent with oviductal transmission of algae from one salamander generation to the next

15

Acetylene reduction by nitrogen-fixing blue-green algae  

Microsoft Academic Search

Known nitrogen-fixing species of blue-green algae are capable of reducing acetylene to ethylene, but acetylene is not reduced by Anacystis nidulans, which does not fix nitrogen. Cycad root nodules which contain blue-green algae as endophytes reduce acetylene. Acetylene reduction is inhibited by carbon monoxide. Nitrate or ammonium-nitrogen has no immediate effect on algae reducing acetylene, but algae grown on nitrate-nitrogen

W. D. P. Stewart; G. P. Fitzgerald; R. H. Burris

1968-01-01

16

Parachloroidium gen. nov. (Trebouxiophyceae, Chlorophyta), a novel genus of coccoid green algae from subaerial corticolous biofilms  

E-print Network

Parachloroidium gen. nov. (Trebouxiophyceae, Chlorophyta), a novel genus of coccoid green algae. Parachloroidium gen. nov. (Trebouxiophyceae, Chlorophyta), a novel genus of coccoid green algae from subaerial the Parachloroidium strains from other similar green algae. However, ultrastructural characteristics and molecular

17

Blue-Green Algae: Why They Become Dominant  

Microsoft Academic Search

The injection of carbon dioxide and the addition of nitrogen and phosphorus to a lake population dominated by blue-green algae results in a rapid shift to dominance by green algae. The basis for the change and its implications are discussed.

Joseph Shapiro

1973-01-01

18

The presence and localization of thioredoxins in diatoms, unicellular algae of secondary endosymbiotic origin.  

PubMed

Diatoms are unicellular algae of great ecological importance. So far, very little is known about the regulation of carbon fixation in these algae; however, there are strong indications that in diatom plastids, the ferredoxin/thioredoxin system might play a minor role in redox regulation of the photosynthetic reactions compared to land plants. Until now, it is unknown whether there are fewer or other target enzymes of thioredoxins in diatoms. Only a single potential target enzyme for thioredoxin, the plastidic fructose-1,6-bisphosphatase, has yet been identified. Nevertheless, during the annotation of the genome of the diatom Phaeodactylum tricornutum, we identified several genes encoding different thioredoxins. Utilizing in vivo expression of GFP:presequence fusion proteins in P. tricornutum, we were able to show that these thioredoxins are targeted either into plastids, mitochondria, or remain in the cytosol. Surprisingly, two of the three usually cytosolic thioredoxin h proteins are apparently plastid associated and, together with a thioredoxin reductase, putatively located in the periplastidic compartment. This is one of the few indications for so far unknown enzymatic reactions in the space between the two pairs of diatom plastid envelope membranes. PMID:19825630

Weber, Till; Gruber, Ansgar; Kroth, Peter G

2009-05-01

19

Diatom/copepod interactions in plankton: the indirect chemical defense of unicellular algae.  

PubMed

Numerous coexisting species can be observed in the open oceans. This includes the complex community of the plankton, which comprises all free floating organisms in the sea. Traditionally, nutrient limitation, competition, predation, and abiotic factors have been assumed to shape the community structure in this environment. Only in recent years has the idea arisen that chemical signals and chemical defense can influence species interactions in the plankton as well. Key players at the base of the marine food web are diatoms (unicellular algae with silicified cell walls) and their main predators, the herbivorous copepods. It was assumed that diatoms represent a generally good food source for the grazers but recent work indicates that some species use chemical defenses. Secondary metabolites, released by these algae immediately after wounding, are targeted not against the predators themselves but rather at interfering with their reproductive success. This strategy allows diatoms to reduce the grazer population, thereby influencing the marine food web. This review addresses the chemical ecology of the defensive oxylipins formed by diatoms and the question of how these metabolites can act in such a dilute environment. Aspects of biosynthesis, bioassays, and the possible implications of such a chemical defense for the plankton community structure are also discussed. PMID:15883976

Pohnert, Georg

2005-06-01

20

Green Autofluorescence in Dinoflagellates, Diatoms, and Other Microalgae and Its Implications for Vital Staining and Morphological Studies? †  

PubMed Central

Green autofluorescence (GAF) has been described in the short flagellum of golden and brown algae, the stigma of Euglenophyceae, and cytoplasm of different life stages of dinoflagellates and is considered by some researchers a valuable taxonomic feature for dinoflagellates. In addition, green fluorescence staining has been widely proposed or adopted to measure cell viability (or physiological state) in areas such as apoptosis of phytoplankton, pollutant stresses on algae, metabolic activity of algae, and testing treatment technologies for ships' ballast water. This paper reports our epifluorescence microscopic observations and quantitative spectrometric measurements of GAF in a broad phylogenetic range of microalgae. Our results demonstrate GAF is a common feature of dinoflagellates, diatoms, green algae, cyanobacteria, and raphidophytes, occurs in the cytoplasm and particularly in eyespots, accumulation bodies, spines, and aerotopes, and is caused by molecules other than chlorophyll. GAF intensity increased with time after cell death or fixation and with excitation by blue or UV light and was affected by pH. GAF of microalgae may be only of limited value in taxonomy. It can be strong enough to interfere with the results of green fluorescence staining, particularly when stained samples are observed microscopically. GAF is useful, however, for microscopic study of algal morphology, especially to visualize cellular components such as eyespots, nucleus, aerotopes, spines, and chloroplasts. Furthermore, GAF can be used to visualize and enumerate dinoflagellate cysts in marine and estuarine sediments in the context of anticipating and monitoring harmful algal blooms and in tracking potentially harmful dinoflagellates transported in ships' ballast tanks. PMID:17277199

Tang, Ying Zhong; Dobbs, Fred C.

2007-01-01

21

RESEARCH ARTICLE Open Access Origin of land plants: Do conjugating green algae  

E-print Network

RESEARCH ARTICLE Open Access Origin of land plants: Do conjugating green algae hold the key? Sabina (embryophytes) evolved from streptophyte algae, also referred to as charophycean algae. The streptophyte algae are a paraphyletic group of green algae, ranging from unicellular flagellates to morphologically complex forms

22

Plastid proteome prediction for diatoms and other algae with secondary plastids of the red lineage.  

PubMed

The plastids of ecologically and economically important algae from phyla such as stramenopiles, dinoflagellates and cryptophytes were acquired via a secondary endosymbiosis and are surrounded by three or four membranes. Nuclear-encoded plastid-localized proteins contain N-terminal bipartite targeting peptides with the conserved amino acid sequence motif 'ASAFAP'. Here we identify the plastid proteomes of two diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum, using a customized prediction tool (ASAFind) that identifies nuclear-encoded plastid proteins in algae with secondary plastids of the red lineage based on the output of SignalP and the identification of conserved 'ASAFAP' motifs and transit peptides. We tested ASAFind against a large reference dataset of diatom proteins with experimentally confirmed subcellular localization and found that the tool accurately identified plastid-localized proteins with both high sensitivity and high specificity. To identify nucleus-encoded plastid proteins of T. pseudonana and P. tricornutum we generated optimized sets of gene models for both whole genomes, to increase the percentage of full-length proteins compared with previous assembly model sets. ASAFind applied to these optimized sets revealed that about 8% of the proteins encoded in their nuclear genomes were predicted to be plastid localized and therefore represent the putative plastid proteomes of these algae. PMID:25438865

Gruber, Ansgar; Rocap, Gabrielle; Kroth, Peter G; Armbrust, E Virginia; Mock, Thomas

2015-02-01

23

Chemoreception in the green alga Dunaliella tertiolecta  

Microsoft Academic Search

A capillary assay was employed to quantify positive chemotactic responses in the motile, unicellular, marine algaDunaliella tertiolecta. Among a wide range of inorganic and organic compounds tested, only ammonium ion,l-tyrosine,l-tryptophan, andl-phenylalanine were found to be major atractants for the chlorophyte.l-Methionine andl-cysteine weakly attracted the alga at 10?3 M. The minimum concentration of the major attractants needed to elicit an observable

Roy D. Sjoblad; Ilan Chet; Ralph Mitchellw

1978-01-01

24

Green algae to land plants: An evolutionary transition  

Microsoft Academic Search

Studies focused upon the evolutionary transition from ancestral green algae to the earliest land plants are important from\\u000a a range of ecological, molecular and evolutionary perspectives. A substantial suite of ultrastructural, biochemical and molecular\\u000a data supports the concept that land plants (embryophytes) are monophyletically derived from an ancestral charophycean alga.\\u000a However, the details of phylogenetic branching patterns linking extant charophytes

Linda E. Graham

1996-01-01

25

DNA is present in the pyrenoid core of the siphonous green algae of the genus Caulerpa and yellow-green algae of the genus Pseudodichotomosiphon  

Microsoft Academic Search

Summary The pyrenoids of a number of siphonous green and yellow-green algae have been examined for the presence of chloroplast DNA (chloroplast nucleoids). We have found a conspicuous localization of chloroplast DNA in the pyrenoid core ofCaulerpa lentillifera andC. fergusonii (siphonous green algae), andPseudodichotomosiphon constrictus (a siphonous yellow-green alga) using fluorescence microscopy after staining with the DNA specific fluorochrome 4',6-diamidino-2-phenylindole

S. Miyamura; T. Hori

1991-01-01

26

Development of Green Fuels From Algae - The University of Tulsa  

SciTech Connect

The general public has become increasingly aware of the pitfalls encountered with the continued reliance on fossil fuels in the industrialized world. In response, the scientific community is in the process of developing non-fossil fuel technologies that can supply adequate energy while also being environmentally friendly. In this project, we concentrate on â??green fuelsâ?ť which we define as those capable of being produced from renewable and sustainable resources in a way that is compatible with the current transportation fuel infrastructure. One route to green fuels that has received relatively little attention begins with algae as a feedstock. Algae are a diverse group of aquatic, photosynthetic organisms, generally categorized as either macroalgae (i.e. seaweed) or microalgae. Microalgae constitute a spectacularly diverse group of prokaryotic and eukaryotic unicellular organisms and account for approximately 50% of global organic carbon fixation. The PIâ??s have subdivided the proposed research program into three main research areas, all of which are essential to the development of commercially viable algae fuels compatible with current energy infrastructure. In the fuel development focus, catalytic cracking reactions of algae oils is optimized. In the species development project, genetic engineering is used to create microalgae strains that are capable of high-level hydrocarbon production. For the modeling effort, the construction of multi-scaled models of algae production was prioritized, including integrating small-scale hydrodynamic models of algae production and reactor design and large-scale design optimization models.

Crunkleton, Daniel; Price, Geoffrey; Johannes, Tyler; Cremaschi, Selen

2012-12-03

27

Photosynthetic H2 metabolism in Chlamydomonas reinhardtii (unicellular green algae).  

PubMed

Unicellular green algae have the ability to operate in two distinctly different environments (aerobic and anaerobic), and to photosynthetically generate molecular hydrogen (H2). A recently developed metabolic protocol in the green alga Chlamydomonas reinhardtii permitted separation of photosynthetic O2-evolution and carbon accumulation from anaerobic consumption of cellular metabolites and concomitant photosynthetic H2-evolution. The H2 evolution process was induced upon sulfate nutrient deprivation of the cells, which reversibly inhibits photosystem-II and O2-evolution in their chloroplast. In the absence of O2, and in order to generate ATP, green algae resorted to anaerobic photosynthetic metabolism, evolved H2 in the light and consumed endogenous substrate. This study summarizes recent advances on green algal hydrogen metabolism and discusses avenues of research for the further development of this method. Included is the mechanism of a substantial tenfold starch accumulation in the cells, observed promptly upon S-deprivation, and the regulated starch and protein catabolism during the subsequent H2-evolution. Also discussed is the function of a chloroplast envelope-localized sulfate permease, and the photosynthesis-respiration relationship in green algae as potential tools by which to stabilize and enhance H2 metabolism. In addition to potential practical applications of H2, approaches discussed in this work are beginning to address the biochemistry of anaerobic H2 photoproduction, its genes, proteins, regulation, and communication with other metabolic pathways in microalgae. Photosynthetic H2 production by green algae may hold the promise of generating a renewable fuel from nature's most plentiful resources, sunlight and water. The process potentially concerns global warming and the question of energy supply and demand. PMID:17721788

Melis, Anastasios

2007-10-01

28

FL47CH15-Goldstein ARI 25 November 2014 9:45 Green Algae as Model  

E-print Network

FL47CH15-Goldstein ARI 25 November 2014 9:45 Green Algae as Model Organisms for Biological Fluid green algae, spanning from the unicellular Chlamydomonas to multicellular Volvox, have emerged as model of flagellar synchronization. Green algae are well suited to the study of such problems because of their range

Goldstein, Raymond E.

29

Xylochloris irregularis gen. et sp. nov. (Trebouxiophyceae, Chlorophyta), a novel subaerial coccoid green alga  

E-print Network

green alga JIR I´ NEUSTUPA 1 *, MAREK ELIA´ S1 , PAVEL SKALOUD 1 , YVONNE NE MCOVA´ 1 AND LENKA irregularis gen. et sp. nov. (Trebouxiophyceae, Chlorophyta), a novel subaerial coccoid green alga. Phycologia 50: 57­66. DOI: 10.2216/08-64.1 The phylogenetic diversity of subaerial coccoid green algae remains

30

Toxins of a Blue-Green Alga: Similarity to Saxitoxin  

Microsoft Academic Search

Toxins were isolated from the freshwater blue-green alga Aphanizomenon flos-aquae. The toxic fractions were characterized by paper and thin-layer chromatography, isolation characteristics, infrared spectra, physiological activity, and reactivity with specific color reagents. The toxic fractions appear to be similar, if not identical, to saxitoxin (paralytic shellfish toxin), which is produced by the marine dinoflagellate Gonyaulax catenella.

Eugene Jackim; John Gentile

1968-01-01

31

Photosynthetic hydrogen and oxygen production by green algae  

Microsoft Academic Search

An overview of photosynthetic hydrogen and oxygen production by green algae in the context of its potential as a renewable chemical feed stock and energy carrier is presented. Beginning with its discovery by Gaffron and Rubin in 1942, motivated by curiosity-driven laboratory research, studies were initiated in the early 1970s that focused on photosynthetic hydrogen production from an applied perspective.

E. Greenbaum; J. W. Lee

1997-01-01

32

Oleosin of subcellular lipid droplets evolved in green algae.  

PubMed

In primitive and higher plants, intracellular storage lipid droplets (LDs) of triacylglycerols are stabilized with a surface layer of phospholipids and oleosin. In chlorophytes (green algae), a protein termed major lipid-droplet protein (MLDP) rather than oleosin on LDs was recently reported. We explored whether MLDP was present directly on algal LDs and whether algae had oleosin genes and oleosins. Immunofluorescence microscopy revealed that MLDP in the chlorophyte Chlamydomonas reinhardtii was associated with endoplasmic reticulum subdomains adjacent to but not directly on LDs. In C. reinhardtii, low levels of a transcript encoding an oleosin-like protein (oleolike) in zygotes-tetrads and a transcript encoding oleosin in vegetative cells transferred to an acetate-enriched medium were found in transcriptomes and by reverse transcription-polymerase chain reaction. The C. reinhardtii LD fraction contained minimal proteins with no detectable oleolike or oleosin. Several charophytes (advanced green algae) possessed low levels of transcripts encoding oleosin but not oleolike. In the charophyte Spirogyra grevilleana, levels of oleosin transcripts increased greatly in cells undergoing conjugation for zygote formation, and the LD fraction from these cells contained minimal proteins, two of which were oleosins identified via proteomics. Because the minimal oleolike and oleosins in algae were difficult to detect, we tested their subcellular locations in Physcomitrella patens transformed with the respective algal genes tagged with a Green Fluorescent Protein gene and localized the algal proteins on P. patens LDs. Overall, oleosin genes having weak and cell/development-specific expression were present in green algae. We present a hypothesis for the evolution of oleosins from algae to plants. PMID:23391579

Huang, Nan-Lan; Huang, Ming-Der; Chen, Tung-Ling L; Huang, Anthony H C

2013-04-01

33

Carnets de Gologie / Notebooks on Geology -Article 2006/03 (CG2006_A03) Are the green algae (phylum Viridiplantae)  

E-print Network

Carnets de GĂ©ologie / Notebooks on Geology - Article 2006/03 (CG2006_A03) 1 Are the green algae planet, A.H. KNOLL states that the first documented fossils of green algae date back 750 Ma. However" and of a primitive clade of green algae, the Pyramimonadales. A paraphyletic group of unicellular green algae, named

Paris-Sud XI, Université de

34

Cycloartane triterpenes from marine green alga Cladophora fascicularis  

NASA Astrophysics Data System (ADS)

Six cycloartanes were isolated from ethanol extract of marine green alga Cladophora fascicularis by column chromatography. Procedure of isolation and description of these compounds are given in this paper. The structures were elucidated as (1). 24-hydroperoxycycloart-25- en-3?-ol; (2). cycloart-25-en-3? 24-diol; (3). 25-hydroperoxycycloart-23-en-3?-ol; (4). cycloart-23-en-3?, 25-diol; (5). cycloart-23, 25-dien-3?-ol; and (6). cycloart-24-en-3?-ol by spectroscopic (MS, ID and 2D NMR) data analysis. Cycloartane derivatives are widely distributed in terrestrial plants, but only few were obtained in the alga. All these compounds that have been isolated from terrestrial plants, were found in the marine alga for the first time.

Huang, Xinping; Zhu, Xiaobin; Deng, Liping; Deng, Zhiwei; Lin, Wenhan

2006-12-01

35

Oxygen Isotope Fractionation during Photosynthesis in a Blue-Green and a Green Alga 12  

PubMed Central

Oxygen isotope fractionation (18O/16O) at the natural abundance level has been measured during photosynthesis of a blue-green and a green alga. When sufficient attention is paid to removal of contaminating air O2 before and during the experiments, then the photosynthetic O2 evolved, as compared to the water O2, had an average difference of ?0.36% for a blue-green alga and ?0.80% for a green alga. These experiments suggest that there is no reason to invoke an inverse isotope effect in photosynthesis as part of the explanation for the 18O enrichment in atmospheric O2 relative to O2 in oceanic waters. In addition, in an indirect way, the experiments also support the argument that the bulk of O2 evolved during photosynthesis comes from water. A 10% contribution of O2 arising from CO2 would have been detectable in the present work. PMID:16659241

Stevens, Catherine L. R.; Schultz, David; Van Baalen, Chase; Parker, Patrick L.

1975-01-01

36

Green Algae as Model Organisms for Biological Fluid Dynamics  

E-print Network

In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these re...

Goldstein, Raymond E

2014-01-01

37

Green Algae as Model Organisms for Biological Fluid Dynamics  

E-print Network

In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.

Raymond E. Goldstein

2014-09-08

38

Green Algae as Model Organisms for Biological Fluid Dynamics  

NASA Astrophysics Data System (ADS)

In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.

Goldstein, Raymond E.

2015-12-01

39

The problems of Prochloron. [evolution of green algae  

NASA Technical Reports Server (NTRS)

Prokaryotic green algae (prochlorophytes), which contain chlorophylls a and b but no bilin pigments, may be phylogenetically related to ancestral chloroplasts if symbiogenesis occurred. They may be otherwise related to eukaryotic chlorophytes. They could have evolved from cyanophytes by loss of phycobilin and gain of chlorophyll b synthesis. These possibilities are briefly discussed. Relevant evidence from biochemical studies in many collaborative laboratories is now becoming available for the resolution of such questions.

Lewin, R. A.

1983-01-01

40

Gain and loss of elongation factor genes in green algae  

PubMed Central

Background Two key genes of the translational apparatus, elongation factor-1 alpha (EF-1?) and elongation factor-like (EFL) have an almost mutually exclusive distribution in eukaryotes. In the green plant lineage, the Chlorophyta encode EFL except Acetabularia where EF-1? is found, and the Streptophyta possess EF-1? except Mesostigma, which has EFL. These results raise questions about evolutionary patterns of gain and loss of EF-1? and EFL. A previous study launched the hypothesis that EF-1? was the primitive state and that EFL was gained once in the ancestor of the green plants, followed by differential loss of EF-1? or EFL in the principal clades of the Viridiplantae. In order to gain more insight in the distribution of EF-1? and EFL in green plants and test this hypothesis we screened the presence of the genes in a large sample of green algae and analyzed their gain-loss dynamics in a maximum likelihood framework using continuous-time Markov models. Results Within the Chlorophyta, EF-1? is shown to be present in three ulvophycean orders (i.e., Dasycladales, Bryopsidales, Siphonocladales) and the genus Ignatius. Models describing gene gain-loss dynamics revealed that the presence of EF-1?, EFL or both genes along the backbone of the green plant phylogeny is highly uncertain due to sensitivity to branch lengths and lack of prior knowledge about ancestral states or rates of gene gain and loss. Model refinements based on insights gained from the EF-1? phylogeny reduce uncertainty but still imply several equally likely possibilities: a primitive EF-1? state with multiple independent EFL gains or coexistence of both genes in the ancestor of the Viridiplantae or Chlorophyta followed by differential loss of one or the other gene in the various lineages. Conclusion EF-1? is much more common among green algae than previously thought. The mutually exclusive distribution of EF-1? and EFL is confirmed in a large sample of green plants. Hypotheses about the gain-loss dynamics of elongation factor genes are hard to test analytically due to a relatively flat likelihood surface, even if prior knowledge is incorporated. Phylogenetic analysis of EFL genes indicates misinterpretations in the recent literature due to uncertainty regarding the root position. PMID:19216746

Cocquyt, Ellen; Verbruggen, Heroen; Leliaert, Frederik; Zechman, Frederick W; Sabbe, Koen; De Clerck, Olivier

2009-01-01

41

Ingestion, assimilation, survival, and reproduction by Daphnia pulex fed seven species of blue-green algae  

Microsoft Academic Search

Daphnia p&x (Crustacea, Cladocera) was fed the blue-green algae (Cyanophyceae) Anacystis nidulans, Synechococcus elongata, S. cedrorum, Merismopedia sp., Anabaena flos- aquae, Synechocystis sp., and Gloeocapsa alpicola. The green algae ( Chlorophyceae) Ankis- trodesmus falcatus and Chlorella uulgaris were used for comparison. Direct observations were made of D. pulex feeding in depression slides filled with the test food. Food labeled with

DEAN E. ARNOLD

1971-01-01

42

Facts about Cyanobacteria (Blue-green Algae) and Cyanobacterial Harmful Algal Blooms  

E-print Network

#12;1 Facts about Cyanobacteria (Blue-green Algae) and Cyanobacterial Harmful Algal Blooms (CyanoHABs) Cyanobacteria (blue-green algae) Cyanobacteria are bacteria that grow in water and are photosynthetic (use sunlight to create food and support life). Cyanobacteria live

43

Antiprotozoal, antimycobacterial and cytotoxic potential of some british green algae.  

PubMed

In the continuation of our search for natural sources for antiprotozoal and antitubercular molecules, we have screened the crude extracts of four green marine algae (Cladophora rupestris, Codium fragile ssp. tomentosoides, Ulva intestinalis and Ulva lactuca) collected from the Dorset area of England. Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and Mycobacterium tuberculosis were used as test organisms in the in vitro assays. The selective toxicity of the extracts was also determined toward mammalian skeletal myoblast (L6) cells. The crude seaweed extracts had no activity against M. tuberculosis, but showed antiprotozoal activity against at least two protozoan species. All algal extracts were active against T. brucei rhodesiense, with C. rupestris being the most potent one (IC(50) value 3.7 microg/ml), whilst only C. rupestris and U. lactuca had moderate trypanocidal activity against T. cruzi (IC(50) values 80.8 and 34.9 microg/ml). Again, all four extracts showed leishmanicidal activity with IC(50) values ranging between 12.0 and 20.2 microg/ml. None of the extracts showed cytotoxicity toward L6 cells, indicating that their antiprotozoal activity is specific. This is the first study reporting antiprotozoal and antimycobacterial activity of British marine algae. PMID:19960429

Spavieri, Jasmine; Kaiser, Marcel; Casey, Rosalyn; Hingley-Wilson, Suzie; Lalvani, Ajit; Blunden, Gerald; Tasdemir, Deniz

2010-07-01

44

Cellular response of freshwater green algae to perfluorooctanoic acid toxicity.  

PubMed

Perfluorooctanoic acid (PFOA) is a kind of persistent organic pollutants and its aquatic eco-toxicity has attracted wide attention; however, the mechanism involved in its toxicity as well as the cell response against PFOA have not been well established. Herein, using single-celled green algae Chlorella pyrenoidosa and Selenastrum capricornutum at the logarithmic growth stage as test organisms, we studied the toxic effects of PFOA on the cell permeability, The 96 h-EC(50) values of PFOA for C. pyrenoidosa and S. capricornutum were 207.46 mg L(-1) and 190.99 mg L(-1), respectively, lower than the 96 h-EC(50) values reported in the literatures. After 96 h of PFOA exposure, the permeability of the cell membranes of both algae was significantly decreased, and the chlorophyll concentration mirrored the trends of algal growth. In both algal species, after a 192-h exposure to a low concentration of PFOA, the activities of superoxide dismutase and catalase were greater than those of the control. At higher concentrations of PFOA, activities of superoxide dismutase and catalase were strongly inhibited. These results indicate that long-term exposure to low levels of PFOA may induce excessive generation of reactive oxygen species in algal cells, causing oxidative damage to cells. PMID:23183033

Xu, Dongmei; Li, Chandan; Chen, Hong; Shao, Bo

2013-02-01

45

Molecular Characterization of Epiphytic Bacterial Communities on Charophycean Green Algae  

PubMed Central

Epiphytic bacterial communities within the sheath material of three filamentous green algae, Desmidium grevillii, Hyalotheca dissiliens, and Spondylosium pulchrum (class Charophyceae, order Zygnematales), collected from a Sphagnum bog were characterized by PCR amplification, cloning, and sequencing of 16S ribosomal DNA. A total of 20 partial sequences and nine different sequence types were obtained, and one sequence type was recovered from the bacterial communities on all three algae. By phylogenetic analysis, the cloned sequences were placed into several major lineages of the Bacteria domain: the Flexibacter/Cytophaga/Bacteroides phylum and the ?, ?, and ? subdivisions of the phylum Proteobacteria. Analysis at the subphylum level revealed that the majority of our sequences were not closely affiliated with those of known, cultured taxa, although the estimated evolutionary distances between our sequences and their nearest neighbors were always less than 0.1 (i.e., greater than 90% similar). This result suggests that the majority of sequences obtained in this study represent as yet phenotypically undescribed bacterial species and that the range of bacterial-algal interactions that occur in nature has not yet been fully described. PMID:9797295

Fisher, Madeline M.; Wilcox, Lee W.; Graham, Linda E.

1998-01-01

46

Enhanced Genetic Tools for Engineering Multigene Traits into Green Algae  

PubMed Central

Transgenic microalgae have the potential to impact many diverse biotechnological industries including energy, human and animal nutrition, pharmaceuticals, health and beauty, and specialty chemicals. However, major obstacles to sophisticated genetic and metabolic engineering in algae have been the lack of well-characterized transformation vectors to direct engineered gene products to specific subcellular locations, and the inability to robustly express multiple nuclear-encoded transgenes within a single cell. Here we validate a set of genetic tools that enable protein targeting to distinct subcellular locations, and present two complementary methods for multigene engineering in the eukaryotic green microalga Chlamydomonas reinhardtii. The tools described here will enable advanced metabolic and genetic engineering to promote microalgae biotechnology and product commercialization. PMID:24710110

Rasala, Beth A.; Chao, Syh-Shiuan; Pier, Matthew; Barrera, Daniel J.; Mayfield, Stephen P.

2014-01-01

47

AIDS-antiviral sulfolipids from cyanobacteria (blue-green algae).  

PubMed

A recently developed tetrazolium-based microculture assay was used to screen extracts of cultured cyanobacteria (blue-green algae) for inhibition of the cytopathic effects of the human immunodeficiency virus (HIV-1), which is implicated as a causative agent of AIDS. A number of extracts were found to be remarkably active against the AIDS virus. A new class of HIV-1-inhibitory compounds, the sulfonic acid-containing glycolipids, was discovered through the use of the microculture assay to guide the fractionation and purification process. The pure compounds were active against HIV-1 in cultured human lymphoblastoid CEM, MT-2, LDV-7, and C3-44 cell lines in the tetrazolium assay as well as in p24 viral protein and syncytium formation assays. PMID:2502635

Gustafson, K R; Cardellina, J H; Fuller, R W; Weislow, O S; Kiser, R F; Snader, K M; Patterson, G M; Boyd, M R

1989-08-16

48

Eyespot placement and assembly in the green alga Chlamydomonas.  

PubMed

The eyespot organelle of the green alga Chlamydomonas allows the cell to phototax toward (or away) from light to maximize the light intensity for photosynthesis and minimize photo-damage. At cytokinesis, the eyespot is resorbed at the cleavage furrow and two new eyespots form in the daughter cells 180 degrees from each other. The eyespots are positioned asymmetrically with respect to the microtubule cytoskeleton. Eyespots are assembled from all three chloroplast membranes and carotenoid-filled granules, which form a sandwich structure overlaid by the tightly apposed plasma membrane. This review describes (1) my interest in cellular asymmetry and organelle biology, (2) isolation of mutations that describe four genes governing eyespot placement and assembly, (3) the characterization of the EYE2 gene, which encodes a thioredoxin superfamily member, and (4) the characterization of the MIN1 gene, which is required for the layered organization of granules and membranes in the eyespot. BioEssays 25:410-416, 2003. PMID:12655648

Dieckmann, Carol L

2003-04-01

49

Photoperiod influences endogenous indoleamines in cultured green alga Dunaliella bardawil.  

PubMed

Effect of light intensity and photoperiod on growth, indoleamines and carotenoid production was studied in unicellular green algae D. bardawil. Maximum biomass and carotenoid contents were found when cultures were grown in light (intensity of 2.0 Klux) at a photoperiod of 16/8h light and dark cycle. There was a profound influence of tested photoperiod conditions of light:dark viz. 8:16, 10:14, and 12:12 hr, continuous light on indoleamines (SER and MEL) production as estimated by HPLC and confirmed by mass spectral data obtained from LC-MS-ESI studies. Serotonin level increased from 908 to 1765 pg/g fresh wt with increase in light duration and melatonin level increased from 267 to 584 pg/g fresh wt during increase in dark phase. Carotenoids production was high in continuous light than other tested conditions. PMID:21452604

Ramakrishna, A; Dayananda, C; Giridhar, P; Rajasekaran, T; Ravishankar, G A

2011-03-01

50

Measurement of rates of grazing of the ostracod Cyprinotus carolinensis on blue-green algae  

Microsoft Academic Search

Measurements were made of the rates of grazing of the ostracod Cyprinotus carolinensis fed 14C-labelled filamentous blue-green algae (cyanobacteria). The grazing rate was a linear function of food concentration at densities below 1.1 µg dry weight of algae · ml-1 and independent of concentration at densities above 11.5 µg algae · ml-1. Starvation affected grazing rates significantly, but light vs.

I. F. Grant; E. A. Egan; M. Alexander

1983-01-01

51

The Cell Walls of Green Algae: A Journey through Evolution and Diversity  

PubMed Central

The green algae represent a large group of morphologically diverse photosynthetic eukaryotes that occupy virtually every photic habitat on the planet. The extracellular coverings of green algae including cell walls are also diverse. A recent surge of research in green algal cell walls fueled by new emerging technologies has revealed new and critical insight concerning these coverings. For example, the late divergent taxa of the Charophycean green algae possess cell walls containing assemblages of polymers with notable similarity to the cellulose, pectins, hemicelluloses, arabinogalactan proteins (AGPs), extensin, and lignin present in embryophyte walls. Ulvophycean seaweeds have cell wall components whose most abundant fibrillar constituents may change from cellulose to ?-mannans to ?-xylans and during different life cycle phases. Likewise, these algae produce complex sulfated polysaccharides, AGPs, and extensin. Chlorophycean green algae produce a wide array of walls ranging from cellulose–pectin complexes to ones made of hydroxyproline-rich glycoproteins. Larger and more detailed surveys of the green algal taxa including incorporation of emerging genomic and transcriptomic data are required in order to more fully resolve evolutionary trends within the green algae and in relationship with higher plants as well as potential applications of wall components in the food and pharmaceutical industries. PMID:22639667

Domozych, David S.; Ciancia, Marina; Fangel, Jonatan U.; Mikkelsen, Maria Dalgaard; Ulvskov, Peter; Willats, William G. T.

2012-01-01

52

Oxidative stress tolerance in the filamentous green algae Cladophora glomerata and Enteromorpha ahlneriana  

Microsoft Academic Search

Cladophora glomerata (L.) Kütz. and Enteromorpha ahlneriana Bliding are morphologically similar filamentous green algae that are dominants in the upper littoral zone of the brackish Baltic Sea. As these two species co-exist in a continuously fluctuating environment, we hypothesised that they may have different strategies to cope with oxidative stress. This was tested in laboratory experiments through stressing the algae

Kyung-sil Choo; Pauli Snoeijs; Marianne Pedersén

2004-01-01

53

Green Pacific Biologicals Rapid & stable nuclear genetic engineering of eukaryotic algae  

E-print Network

to Investors · Rapid & stable nuclear genetic engineering of eukaryotic algae · WW exclusive license Max Planck's competitive advantage? Rapid & stable algae nuclear genetic engineering Wild-typeWild-typeWild-type GPBStrainGPBStrainGPBStrain #12;Green Pacific Biologicals Organism with high levels of oils Powerful genetic engineering GPB [no

54

JENUFA GEN. NOV.: A NEW GENUS OF COCCOID GREEN ALGAE (CHLOROPHYCEAE, INCERTAE SEDIS) PREVIOUSLY RECORDED BY ENVIRONMENTAL SEQUENCING1  

E-print Network

JENUFA GEN. NOV.: A NEW GENUS OF COCCOID GREEN ALGAE (CHLOROPHYCEAE, INCERTAE SEDIS) PREVIOUSLY of unicellular green algae from algal biofilms growing on tree bark in a Southeast Asian tropical rainforest: AU, approximately unbiased; BBM, Bold basal medium; CAUP, Culture Collection of algae at Charles

55

A biologically active diphenyl ether from the green alga Cladophora fascicularis  

Microsoft Academic Search

Summary A new polybrominated diphenyl ether (1) has been isolated from the green algaCladaphora fascicularis, and the structure was determined by spectral analysis and conversion to known compounds. It showed antibacterial and antiinflammatory activities.

M. Kuniyoshi; K. Yamada; T. Higa

1985-01-01

56

Production and release of selenocyanate by different green freshwater algae in environmental and laboratory samples.  

PubMed

In a previous study, selenocyanate was tentatively identified as a biotransformation product when green algae were exposed to environmentally relevant concentrations of selenate. In this follow-up study, we confirm conclusively the presence of selenocyanate in Chlorella vulgaris culture medium by electrospray mass spectrometry, based on selenium's known isotopic pattern. We also demonstrate that the observed phenomenon extends to other green algae (Chlorella kesslerii and Scenedesmus obliquus) and at least one species of blue-green algae (Synechococcus leopoliensis). Further laboratory experiments show that selenocyanate production by algae is enhanced by addition of nitrate, which appears to serve as a source of cyanide produced in the algae. Ultimately, this biotransformation process was confirmed in field experiments where trace amounts of selenocyanate (0.215 ± 0.010 ppb) were observed in a eutrophic, selenium-impacted river with massive algal blooms, which consisted of filamentous green algae (Cladophora genus) and blue-green algae (Anabaena genus). Selenocyanate abundance was low despite elevated selenium concentrations, apparently due to suppression of selenate uptake by sulfate, and insufficient nitrogen concentrations. Finally, trace levels of several other unidentified selenium-containing compounds were observed in these river water samples; preliminary suggestions for their identities include thioselenate and small organic Se species. PMID:22455319

LeBlanc, Kelly L; Smith, Matthew S; Wallschläger, Dirk

2012-06-01

57

Biochemical Basis ofObligate Autotrophy in Blue-Green Algae andThiobacilli  

Microsoft Academic Search

Differential rates ofincorporation ofsugars,organic acids, andaminoacids during autotrophic growth ofseveral blue-green algae andthiobacilli havebeendetermined. Inobligate autotrophs (both blue-green algae andthiobacilli), exogenously fur- nished organic compounds makea verysmallcontribution tocellular carbon; ace- tate, themostreadily incorporated compound ofthose studied, contributes about 10% ofnewlysynthesized cellular carbon. InThiobacillus intermedius, a facultative chemoautotroph, acetate contributes over40%ofnewly synthesized cellular carbon, andsuccinate andglutamate almost 90%.Intheobligate autotrophs, carbon from

ARNOLD J. SMITH; ROGER Y. STANIER

1967-01-01

58

Polysaccharides and sterols from green algae Caulerpa lentillifera and C. sertularioides  

Microsoft Academic Search

Sterols and polysaccharides of green alga Caulerpa lentillifera grown under laboratory conditions and in mariculture and polysaccharides of green alga C. sertularioides grown under natural conditions were studied. The sterol fraction consisted of C27-C29 steroidal alcohols with ?5-unsaturation in the steroid core regardless of the growth conditions. The dominant (79.9%) steroid component of the sterol\\u000a fraction was clionasterol. The water-soluble

N. M. Shevchenko; Yu. V. Burtseva; T. N. Zvyagintseva; O. S. Sergeeva; A. M. Zakharenko; V. V. Isakov; Nguyen Thi Linh; Nguyen Xuan Hoa; Bui Minh Ly; Pham Van Huyen

2009-01-01

59

Algae as Protein Factories: Expression of a Human Antibody and the Respective Antigen in the Diatom Phaeodactylum tricornutum  

PubMed Central

Microalgae are thought to offer great potential as expression system for various industrial, therapeutic and diagnostic recombinant proteins as they combine high growth rates with all benefits of eukaryotic expression systems. Moreover, microalgae exhibit a phototrophic lifestyle like land plants, hence protein expression is fuelled by photosynthesis, which is CO2-neutral and involves only low production costs. So far, however, research on algal bioreactors for recombinant protein expression is very rare calling for further investigations in this highly promising field. In this study, we present data on the expression of a monoclonal human IgG antibody against the Hepatitis B surface protein and the respective antigen in the diatom Phaeodactylum tricornutum. Antibodies are fully-assembled and functional and accumulate to 8.7% of total soluble protein, which complies with 21 mg antibody per gram algal dry weight. The Hepatitis B surface protein is functional as well and is recognized by algae-produced and commercial antibodies. PMID:22164289

Hempel, Franziska; Lau, Julia; Klingl, Andreas; Maier, Uwe G.

2011-01-01

60

Production of carbonate sediments by a unicellular green alga  

USGS Publications Warehouse

This study investigates the ability of the unicellular green alga Natmochloris atoimis to precipitate CaCO3, quantifies mineral precipitation rates, estimates sediment production in a N. atomiis bloom, and discusses the implications of microbial calcification for carbonate sediment deposition. A series of N. atomus cultures, isolated from Lake Reeve, Australia, were incubated at various pH and calcium concentrations to determine environmental parameters for calcification. Rates of calcification were calculated from initial and postincubation alkalinity, pH, and calcium measurements. Replicate experiments and controls consisting of non-calcifying cultures, uninoculated media, and dead cell cultures were performed using environmental culture parameters determined in series cultures. Average calcification rates from replicate experiments were used to predict daily sediment production rates in a small bloom of N. atomus. N. atomus precipitates 0.138 g/L of calcite in approximately 4 h when incubated at pH 8.5, 14.24 mM calcium concentration, 33 ??C, 100 ??E/m2/s light intensity, and a cell population density of 107 cells/mL. Assuming continuous precipitation, this corresponds to a maximum estimated sediment production rate of 1.6 ?? 106 kg of CaCO3, per 12 h day in a single bloom of 3.2 ?? 109 L. Our results suggest that microbial calcification contributes significantly to the carbonate sediment budget.

Yates, K.K.; Robbins, L.L.

1998-01-01

61

Phylogenetic and molecular analysis of hydrogen-producing green algae  

PubMed Central

A select set of microalgae are reported to be able to catalyse photobiological H2 production from water. Based on the model organism Chlamydomonas reinhardtii, a method was developed for the screening of naturally occurring H2-producing microalgae. By purging algal cultures with N2 in the dark and subsequent illumination, it is possible to rapidly induce photobiological H2 evolution. Using NMR spectroscopy for metabolic profiling in C. reinhardtii, acetate, formate, and ethanol were found to be key compounds contributing to metabolic variance during the assay. This procedure can be used to test algal species existing as axenic or mixed cultures for their ability to produce H2. Using this system, five algal isolates capable of H2 production were identified in various aquatic systems. A phylogenetic tree was constructed using ribosomal sequence data of green unicellular algae to determine if there were taxonomic patterns of H2 production. H2-producing algal species were seen to be dispersed amongst most clades, indicating an H2-producing capacity preceded evolution of the phylum Chlorophyta. PMID:19342428

Timmins, Matthew; Thomas-Hall, Skye R.; Darling, Aaron; Zhang, Eugene; Hankamer, Ben; Marx, Ute C.; Schenk, Peer M.

2009-01-01

62

The Mitochondrial Genome of the Entomoparasitic Green Alga Helicosporidium  

PubMed Central

Background Helicosporidia are achlorophyllous, non-photosynthetic protists that are obligate parasites of invertebrates. Highly specialized, these pathogens feature an unusual cyst stage that dehisces inside the infected organism and releases a filamentous cell displaying surface projections, which will penetrate the host gut wall and eventually reproduce in the hemolymph. Long classified as incertae sedis or as relatives of other parasites such as Apicomplexa or Microsporidia, the Helicosporidia were surprisingly identified through molecular phylogeny as belonging to the Chlorophyta, a phylum of green algae. Most phylogenetic analyses involving Helicosporidia have placed them within the subgroup Trebouxiophyceae and further suggested a close affiliation between the Helicosporidia and the genus Prototheca. Prototheca species are also achlorophyllous and pathogenic, but they infect vertebrate hosts, inducing protothecosis in humans. The complete plastid genome of an Helicosporidium species was recently described and is a model of compaction and reduction. Here we describe the complete mitochondrial genome sequence of the same strain, Helicosporidium sp. ATCC 50920 isolated from the black fly Simulium jonesi. Methodology/Principal Findings The circular mapping 49343 bp mitochondrial genome of Helicosporidium closely resembles that of the vertebrate parasite Prototheca wickerhamii. The two genomes share an almost identical gene complement and display a level of synteny that is higher than any other sequenced chlorophyte mitochondrial DNAs. Interestingly, the Helicosporidium mtDNA feature a trans-spliced group I intron, and a second group I intron that contains two open reading frames that appear to be degenerate maturase/endonuclease genes, both rare characteristics for this type of intron. Conclusions/Significance The architecture, genome content, and phylogeny of the Helicosporidium mitochondrial genome are all congruent with its close relationship to Prototheca within the Trebouxiophyceae. The Helicosporidium mitochondrial genome does, however, contain a number of novel features, particularly relating to its introns. PMID:20126458

Pombert, Jean-François; Keeling, Patrick J.

2010-01-01

63

Hidden genetic diversity in the green alga Spirogyra (Zygnematophyceae, Streptophyta)  

PubMed Central

Background The unbranched filamentous green alga Spirogyra (Streptophyta, Zygnemataceae) is easily recognizable based on its vegetative morphology, which shows one to several spiral chloroplasts. This simple structure falsely points to a low genetic diversity: Spirogyra is commonly excluded from phylogenetic analyses because the genus is known as a long-branch taxon caused by a high evolutionary rate. Results We focused on this genetic diversity and sequenced 130 Spirogyra small subunit nuclear ribosomal DNA (SSU rDNA) strands of different origin. The resulting SSU rDNA sequences were used for phylogenetic analyses using complex evolutionary models (posterior probability, maximum likelihood, neighbor joining, and maximum parsimony methods). The sequences were between 1672 and 1779 nucleotides long. Sequence comparisons revealed 53 individual clones, but our results still support monophyly of the genus. Our data set did not contain a single slow-evolving taxon that would have been placed on a shorter branch compared to the remaining sequences. Out of 130 accessions analyzed, 72 showed a secondary loss of the 1506 group I intron, which formed a long-branched group within the genus. The phylogenetic relationship to the genus Spirotaenia was not resolved satisfactorily. The genetic distance within the genus Spirogyra exceeded the distances measured within any other genus of the remaining Zygnemataceae included in this study. Conclusion Overall, we define eight distinct clades of Spirogyra, one of them including the genus Sirogonium. A large number of non-homoplasious synapomorphies (NHS; 114 NHS in total) was found for Spirogyra (41 NHS) and for each clade (totaling 73 NHS). This emphasizes the high genetic diversity of this genus and the distance to the remaining Zygnematophyceae. PMID:22655677

2012-01-01

64

Bioactive constituents from the green alga Caulerpa racemosa.  

PubMed

Three diterpenoids, including a pair of epimers, racemobutenolids A and B (1 and 2), and 4',5'-dehydrodiodictyonema A (3), an ?-tocopheroid, ?-tocoxylenoxy (8), and an 28-oxostigmastane steroid, (23E)-3?-hydroxy-stigmasta-5,23-dien-28-one (11), together with 12 known compounds, were isolated from the green alga Caulerpa racemosa. The structures of the new compounds were elucidated by detailed analysis of spectroscopic data, and by comparison with data for related known compounds. The epimers (1 and 2) are two unusual diterpenoid lactones bearing a ?-methyl-?-substituted butenolide moiety, and 3 and 8 represent the first naturally occurring natural products with a hematinic acid ester group and 3,5-dimethylphenoxy functionality, respectively. The enzyme inhibitory activities of the isolated compounds were evaluated in vitro against PTP1B and related PTPs (TCPTP, CDC25B, LAR, SHP-1, and SHP-2). Compounds 3, 5, 6, and 9-14 exhibited different levels of PTP1B inhibitory activities with IC50 values ranging from 2.30 to 50.02?M. Of these compounds, 3, 9, and 11 showed the most potent inhibitory activities towards PTP1B with IC50 values of 2.30, 3.85, and 3.80?M, respectively. More importantly, the potent PTP1B inhibitors 3, 9, and 11 also displayed high selectivity over the highly homologous TCPTP and other PTPs. Also, the neuroprotective effects of the isolates against A?25-35-induced cell damage in SH-SY5Y cells were investigated. Compounds 10, 11, and 14 exhibited significant neuroprotective effects against A?25-35-induced SH-SY5Y cell damage with 11.31-15.98% increases in cell viability at 10?M. In addition, the cytotoxic activities of the isolated compounds were tested against the human cancer cell lines A-549 and HL-60. PMID:25497963

Yang, Peng; Liu, Ding-Quan; Liang, Tong-Jun; Li, Jia; Zhang, Hai-Yan; Liu, Ai-Hong; Guo, Yue-Wei; Mao, Shui-Chun

2015-01-01

65

Natural Synchronisation for the Study of Cell Divisionin the Green Unicellular Alga Ostreococcus tauri  

Microsoft Academic Search

Ostreococcus tauri (Prasinophyceae) is a marine unicellular green alga which diverged early in the green lineage. The interest of O. tauri as a potential model to study plant cell division is based on its key phylogenetic position, its simple binary division,\\u000a a very simple cellular organisation and now the availability of the full genome sequence. In addition O. tauri has

Benoît Farinas; Camille Mary; Carmem-Lara de O Manes; Yvonne Bhaud; Gérard Peaucellier; Hervé Moreau

2006-01-01

66

Trails of green alga hydrogen research - from hans gaffron to new frontiers.  

PubMed

This paper summarizes aspects of the history of photosynthetic hydrogen research, from the pioneering discovery of Hans Gaffron over 60 years ago to the potential exploitation of green algae in commercial H(2)-production. The trail started as a mere scientific curiosity, but promises to be a most important discovery, one that leads photosynthesis research to important commercial applications. Progress achieved in the field of photosynthetic hydrogen production by green algae includes elucidation of the mechanism, the ability to modify photosynthesis by physiological means and to produce bulk amounts of H(2) gas, and cloning of the [Fe]-hydrogenase genes in several green algal species. PMID:16328836

Melis, Anastasios; Happe, Thomas

2004-01-01

67

Tracing floating green algae blooms in the Yellow Sea and the East China Sea using Lagrangian transport simulations  

NASA Astrophysics Data System (ADS)

Lagrangian particle tracking experiments were conducted to understand the pathway of the floating green algae patches observed in the Yellow Sea (YS) and East China Sea (ECS) in summer 2011. The numerical simulation results indicated that dominant southerly winds during June and July 2011 were related to offshore movement of the floating green algae, especially their eastward extension in the YS/ECS. An infrequent and unusual event occurred in June 2011: a severe Tropical Strom MEARI, caused the green algae to detach from the coast and initiated movement to the east. After the typhoon event, sea surface temperature recovered rapidly enough to grow the floating green algae, and wind and local current controlled the movement of the massive floating algae patches (coastal accumulation or offshore advection in the area). Analysis of the floating green algae movement using satellite images during passage of Typhoon MAON in July 2011 revealed that the floating green algae patches were significantly controlled by both ocean currents and enhanced winds. These findings suggest that the floating green algae bloom off Qingdao, China and in the middle of the YS and ECS in the summer of 2011 occurred due to the combined effects of recent rapid expansion of seaweed aquaculture, strong winds, and the wind patterns in blooming regions. Our combined approach, using satellite data and numerical simulations, provides a robust estimate for tracing and monitoring changes in green algae blooms on a regional scale.

Park, Young-Gyu; Son, Young Baek; Choi, Byoung-Ju; Kim, Yong Hoon

2014-05-01

68

AlgaePath: comprehensive analysis of metabolic pathways using transcript abundance data from next-generation sequencing in green algae  

PubMed Central

Background Algae are important non-vascular plants that have many research applications, including high species diversity, biofuel sources, and adsorption of heavy metals and, following processing, are used as ingredients in health supplements. The increasing availability of next-generation sequencing (NGS) data for algae genomes and transcriptomes has made the development of an integrated resource for retrieving gene expression data and metabolic pathway essential for functional analysis and systems biology. In a currently available resource, gene expression profiles and biological pathways are displayed separately, making it impossible to easily search current databases to identify the cellular response mechanisms. Therefore, in this work the novel AlgaePath database was developed to retrieve transcript abundance profiles efficiently under various conditions in numerous metabolic pathways. Description AlgaePath is a web-based database that integrates gene information, biological pathways, and NGS datasets for the green algae Chlamydomonas reinhardtii and Neodesmus sp. UTEX 2219–4. Users can search this database to identify transcript abundance profiles and pathway information using five query pages (Gene Search, Pathway Search, Differentially Expressed Genes (DEGs) Search, Gene Group Analysis, and Co-expression Analysis). The transcript abundance data of 45 and four samples from C. reinhardtii and Neodesmus sp. UTEX 2219–4, respectively, can be obtained directly on pathway maps. Genes that are differentially expressed between two conditions can be identified using Folds Search. The Gene Group Analysis page includes a pathway enrichment analysis, and can be used to easily compare the transcript abundance profiles of functionally related genes on a map. Finally, the Co-expression Analysis page can be used to search for co-expressed transcripts of a target gene. The results of the searches will provide a valuable reference for designing further experiments and for elucidating critical mechanisms from high-throughput data. Conclusions AlgaePath is an effective interface that can be used to clarify the transcript response mechanisms in different metabolic pathways under various conditions. Importantly, AlgaePath can be mined to identify critical mechanisms based on high-throughput sequencing. To our knowledge, AlgaePath is the most comprehensive resource for integrating numerous databases and analysis tools in algae. The system can be accessed freely online at http://algaepath.itps.ncku.edu.tw. PMID:24628857

2014-01-01

69

The growth and distribution of the green alga Cladophora at Presqu'ile Provincial Park: Implications for management (Ontario)  

Microsoft Academic Search

The Green alga genus Caldophora is one of the most abundant kinds of algae worldwide, found in both freshwater and marine environments. It prefers nutrient-rich waters and requires a rocky substrate and water movement for growth. When water temperatures reach 22 to 26 C, the alga dies and washes into shore in large mats. Dead Cladophora produces a terrible odour,

Dolf Craig DeJong

2000-01-01

70

Bioelectricity generation and microcystins removal in a blue-green algae powered microbial fuel cell.  

PubMed

Bioelectricity production from blue-green algae was examined in a single chamber tubular microbial fuel cell (MFC). The blue-green algae powered MFC produced a maximum power density of 11 4 mW/m(2) at a current density of 0.55 mA/m(2). Coupled with the bioenergy generation, high removal efficiencies of chemical oxygen demand (COD) and nitrogen were also achieved in MFCs. Over 78.9% of total chemical oxygen demand (TCOD), 80.0% of soluble chemical oxygen demand (SCOD), 91.0% of total nitrogen (total-N) and 96.8% ammonium-nitrogen (NH(3)-N) were removed under closed circuit conditions in 12 days, which were much more effective than those under open circuit and anaerobic reactor conditions. Most importantly, the MFC showed great ability to remove microcystins released from blue-green algae. Over 90.7% of MC-RR and 91.1% of MC-LR were removed under closed circuit conditions (500?). This study showed that the MFC could provide a potential means for electricity production from blue-green algae coupling algae toxins removal. PMID:21295401

Yuan, Yong; Chen, Qing; Zhou, Shungui; Zhuang, Li; Hu, Pei

2011-03-15

71

Genomic footprints of a cryptic plastid endosymbiosis in diatoms.  

PubMed

Diatoms and other chromalveolates are among the dominant phytoplankters in the world's oceans. Endosymbiosis was essential to the success of chromalveolates, and it appears that the ancestral plastid in this group had a red algal origin via an ancient secondary endosymbiosis. However, recent analyses have turned up a handful of nuclear genes in chromalveolates that are of green algal derivation. Using a genome-wide approach to estimate the "green" contribution to diatoms, we identified >1700 green gene transfers, constituting 16% of the diatom nuclear coding potential. These genes were probably introduced into diatoms and other chromalveolates from a cryptic endosymbiont related to prasinophyte-like green algae. Chromalveolates appear to have recruited genes from the two major existing algal groups to forge a highly successful, species-rich protist lineage. PMID:19556510

Moustafa, Ahmed; Beszteri, Bánk; Maier, Uwe G; Bowler, Chris; Valentin, Klaus; Bhattacharya, Debashish

2009-06-26

72

Isolation of plasmid from the blue-green alga Spirulina platensis  

NASA Astrophysics Data System (ADS)

CCC plasmid was isolated from an economically important blue-green alga — Spirulina platensis (1.7×106 dalton from the S6 strain and 1.2×106 dalton from the F3 strain) using a rapid method based on ultrasonic disruption of algal cells and alkaline removal of chromosomal DNA. The difference in the molecular weight of the CCC DNAs from the two strains differing in form suggests that plasmid may be related with the differentiation of algal form. This modified method, which does not use any lysozyme, is a quick and effective method of plasmid isolation, especially for filamentous blue-green algae.

Qin, Song; Tong, Shun; Zhang, Peijun; Tseng, C. K.

1993-09-01

73

Uptake and Retention of Cs137 by a Blue-Green Alga in Continuous Flow and Batch Culture Systems  

SciTech Connect

Since routine monitoring data show that blue-green algae concentrate radioactivity from water by factors as great as 10,000, this study was initiated to investigate the uptake and retention patterns of specific radionuclides by the dominant genera of blue-green algae in the reactor effluents. Plectonema purpureum was selected for this study.

Watts, J.R.

2003-02-18

74

Antioxidant Enzyme Activities in the Cyanobacteria Planktothrix Agardhii, Planktothrix Perornata, Raphidiopsis Brookii, and the Green Alga Selenastrum Capricornutum  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous studies have demonstrated that compounds generating reactive oxygen species (ROS) are selectively toxic towards certain species of cyanobacteria (blue-green algae) when compared to green algae (e.g., Selenastrum capricornutum). The antioxidant enzyme activities of S. capricornutum and seve...

75

MOLECULAR CHARACTERIZATION OF THE ASSIMILATORY NITRATE REDUCTASE GENE AND ITS EXPRESSION IN THE MARINE GREEN ALGA DUNALIELLA  

E-print Network

IN THE MARINE GREEN ALGA DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1 Bongkeun Song2 and Bess B. Ward Department from a marine phytoplankton, the green alga Dunaliella tertiolecta Butcher. Its sequence is veryDNA of D. tertiolecta. The complete NR gene of D. tertiolecta is 2.7 kb in size and is similar at the amino

Ward, Bess

76

ASPECTS OF PHOSPHATE UTILIZATION BY BLUE-GREEN ALGAE  

EPA Science Inventory

The effects of various external phosphate concentrations on physiological and cytological aspects of Plectonema boryanum have been studied. P. boryanum was found to tolerate a wide range of phosphate concentrations, from 1 to 1000 mg of phosphate per liter. Growth of the alga in ...

77

Green Autofluorescence in Dinoflagellates, Diatoms, and Other Microalgae and Its Implications for Vital Staining and Morphological Studies  

Microsoft Academic Search

Green autofluorescence (GAF) has been described in the short flagellum of golden and brown algae, the stigma of Euglenophyceae, and cytoplasm of different life stages of dinoflagellates and is considered by some researchers a valuable taxonomic feature for dinoflagellates. In addition, green fluorescence staining has been widely proposed or adopted to measure cell viability (or physiological state) in areas such

Ying Zhong Tang; Fred C. Dobbs

2007-01-01

78

Chloroplast-mitochondria cross-talk in diatoms.  

PubMed

Diatoms are unicellular, mainly photosynthetic, eukaryotes living within elaborate silicified cell walls and believed to be responsible for around 40% of global primary productivity in the oceans. Their abundance in aquatic ecosystems is such that they have on different occasions been described as the insects, the weeds, or the cancer cells of the ocean. In contrast to higher plants and green algae which derive from a primary endosymbiosis, diatoms are now believed to originate from a serial secondary endosymbiosis involving both green and red algae and a heterotrophic exosymbiont host. As a consequence of their dynamic evolutionary history, they appear to have red algal-derived chloroplasts empowered largely by green algal proteins, working alongside mitochondria derived from the non-photosynthetic exosymbiont. This review will discuss the evidence for such an unusual assemblage of organelles in diatoms, and will present the evidence implying that it has enabled them with unorthodox metabolisms that may have contributed to their profound ecological success. PMID:22268145

Prihoda, Judit; Tanaka, Atsuko; de Paula, Wilson B M; Allen, John F; Tirichine, Leďla; Bowler, Chris

2012-02-01

79

Resurrection kinetics of photosynthesis in desiccation-tolerant terrestrial green algae (Chlorophyta) on tree bark.  

PubMed

The rough bark of orchard trees (Malus) around Darmstadt is predominantly covered in red to purple-brown layers (biofilms) of epiphytic terrestrial alga of Trentepohlia umbrina. The smooth bark of forest trees (Fagus sylvatica L. and Acer sp.) in the same area is covered by bright green biofilms composed of the green algae Desmococcus, Apatococcus and Trebouxia, with a few cells of Coccomyxa and 'Chlorella' trebouxioides between them. These algae are desiccation tolerant. After samples of bark with the biofilms were kept in dry air in darkness for various periods of time, potential quantum yield of PSII, F(v)/F(m), recovered during rehydration upon rewetting. The kinetics and degree of recovery depended on the length of time that the algae were kept in dry air in the desiccated state. Recovery was better for green biofilm samples, i.e. quite good even after 80 days of desiccation (F(v)/F(m) = ca. 50% of initial value), than the red samples, where recovery was only adequate up to ca. 30-40 days of desiccation (F(v)/F(m) = ca. 20-55% of initial value). It is concluded that the different bark types constitute different ecophysiological niches that can be occupied by the algae and that can be distinguished by their capacity to recover from desiccation after different times in the dry state. PMID:20522179

Lüttge, U; Büdel, B

2010-05-01

80

Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological and molecular mechanisms  

PubMed Central

Although most green algae typically occur in aquatic ecosystems, many species also live partly or permanently under aeroterrestrial conditions, where the cells are exposed to the atmosphere and hence regularly experience dehydration. The ability of algal cells to survive in an air-dried state is termed desiccation tolerance. The mechanisms involved in desiccation tolerance of green algae are still poorly understood, and hence the aim of this review is to summarize recent findings on the effects of desiccation and osmotic water loss. Starting from structural changes, physiological, and biochemical consequences of desiccation will be addressed in different green-algal lineages. The available data clearly indicate a range of strategies, which are rather different in streptophycean and non-streptophycean green algae. While members of the Trebouxiophyceae exhibit effective water loss-prevention mechanisms based on the biosynthesis and accumulation of particular organic osmolytes such as polyols, these compounds are so far not reported in representatives of the Streptophyta. In members of the Streptophyta such as Klebsormidium, the most striking observation is the appearance of cross-walls in desiccated samples, which are strongly undulating, suggesting a high degree of mechanical flexibility. This aids in maintaining structural integrity in the dried state and allows the cell to maintain turgor pressure for a prolonged period of time during the dehydration process. Physiological strategies in aeroterrestrial green algae generally include a rapid reduction of photosynthesis during desiccation, but also a rather quick recovery after rewetting, whereas aquatic species are sensitive to drying. The underlying mechanisms such as the affected molecular components of the photosynthetic machinery are poorly understood in green algae. Therefore, modern approaches based on transcriptomics, proteomics, and/or metabolomics are urgently needed to better understand the molecular mechanisms involved in desiccation-stress physiology of these organisms. The very limited existing information is described in the present review. PMID:23986769

Holzinger, Andreas; Karsten, Ulf

2013-01-01

81

Genome-wide analysis of tandem repeats in plants and green algae.  

PubMed

Tandem repeats (TRs) extensively exist in the genomes of prokaryotes and eukaryotes. Based on the sequenced genomes and gene annotations of 31 plant and algal species in Phytozome version 8.0 (http://www.phytozome.net/), we examined TRs in a genome-wide scale, characterized their distributions and motif features, and explored their putative biological functions. Among the 31 species, no significant correlation was detected between the TR density and genome size. Interestingly, green alga Chlamydomonas reinhardtii (42,059 bp/Mbp) and castor bean Ricinus communis (55,454 bp/Mbp) showed much higher TR densities than all other species (13,209 bp/Mbp on average). In the 29 land plants, including 22 dicots, 5 monocots, and 2 bryophytes, 5'-UTR and upstream intergenic 200-nt (UI200) regions had the first and second highest TR densities, whereas in the two green algae (C. reinhardtii and Volvox carteri) the first and second highest densities were found in intron and coding sequence (CDS) regions, respectively. In CDS regions, trinucleotide and hexanucleotide motifs were those most frequently represented in all species. In intron regions, especially in the two green algae, significantly more TRs were detected near the intron-exon junctions. Within intergenic regions in dicots and monocots, more TRs were found near both the 5' and 3' ends of genes. GO annotation in two green algae revealed that the genes with TRs in introns are significantly involved in transcriptional and translational processing. As the first systematic examination of TRs in plant and green algal genomes, our study showed that TRs displayed nonrandom distribution for both intragenic and intergenic regions, suggesting that they have potential roles in transcriptional or translational regulation in plants and green algae. PMID:24192840

Zhao, Zhixin; Guo, Cheng; Sutharzan, Sreeskandarajan; Li, Pei; Echt, Craig S; Zhang, Jie; Liang, Chun

2014-01-01

82

Endolithic Blue-Green Algae in the Dry Valleys: Primary Producers in the Antarctic Desert Ecosystem  

Microsoft Academic Search

Endolithic unicellular blue-green algae occur under the surface of orthoquartzite rocks in the dry valleys of southern Victoria Land, Antarctica. This report of primary producers in the Antarctic desert ecosystem suggests that, in future efforts to detect life in extraterrestrial (for example, martian) environments, scientists should consider the possible existence of endolithic life forms.

E. Imre Friedmann; Roseli Ocampo

1976-01-01

83

Phycobilisomes from blue-green and red algae: isolation criteria and dissociation characteristics  

Microsoft Academic Search

A general procedure for the isolation of functionally intact phycobilisomes was devised, based on modifications of previously used procedures. It has been successful with numerous species of red and blue-green algae (Anabaena variabilis, Anacystis nidulans, Agmenellum quadruplicatum, Fremyella diplosiphon, Glaucosphaera vacuolata, Griffithsia pacifica, Nemalion multifidum, Nostoc sp., Phormidium persicinum, Porphyridium cruentum, P. sordidum, P. aerugineum, Rhodosorus marinus). Isolation was carried

E. Gantt; C. A. Lipschultz; J. Grabowski; B. K. Zimmerman

1979-01-01

84

The ultrasmall green alga Ostreococcus unveils a unique regulation of the Calvin cycle  

E-print Network

capable of forming high molecular GADPH complexes GapC: proteobacterial (mitochondrial) origin sequencing:1109-1118, (2006)) Ostreococcus tauri is a unicellular green alga, belonging to the Prasinophyceae. With a size, Mitochondrion; N, nucleus; Np, nuclear pore; P, chloroplast; Sg, starch grain) A B Situation in two Ostreococcus

Gent, Universiteit

85

Photosystem II and Pigment Dynamics among Ecotypes of the Green Alga Ostreococcus1  

E-print Network

Photosystem II and Pigment Dynamics among Ecotypes of the Green Alga Ostreococcus1 Christophe Six2 Ostreococcus ecotypes were all capable of deploying modulation of the photosystem II repair cycle in order in the photosystem II repair cycle in this strain. Moreover, the deepwater Ostreococcus accumulated lutein and showed

Vincent, Warwick F.

86

Microelement composition of the green alga Ulva fenestrata from Peter the Great Bay, Sea of Japan  

Microsoft Academic Search

Concentrations of heavy metals Fe, Mn, Cu, Zn, Pb, Cd, and Ni were determined in the thalluses of the green alga Ulva fenestrata sampled from different locations in Peter the Great Bay (Sea of Japan). According to the metal concentrations in Ulva, the degree of pollution of the surveyed areas in Peter the Great Bay decreases in the following series:

S. I. Kozhenkova; E. N. Chernova; V. M. Shulkin

2006-01-01

87

A STATUS REPORT ON PLANKTONIC CYANOBACTERIA (BLUE-GREEN ALGAE) AND THEIR TOXINS  

EPA Science Inventory

Toxic blue-green algae (cyanobacteria) continue to be agents of certain waterbased toxicoses. heir presence is now being acknowledged in many of the world's fresh and brackish waters with eutrophication status of meso to hypereutrophic. ense surface scums called waterblooms will ...

88

Assessing Potential Health Risks from Microcystin Toxins in Blue-Green Algae Dietary Supplements  

Microsoft Academic Search

The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and

Duncan J. Gilroy; Kenneth W. Kauffman; Ronald A. Hall; Xuan Huang; Fun S. Chu

89

Original article Fermentation of green alga sea-lettuce (Ulva sp)  

E-print Network

Original article Fermentation of green alga sea-lettuce (Ulva sp) and metabolism of its sulphate). The purpose of this study was to assess the fermentation characteristics and sulphate metabolism of Ulva and ulvan by human faecal bacteria fermentation system using a semi-continu- ous fermenter. Ulva and ulvan

Paris-Sud XI, Université de

90

Oleosin of Subcellular Lipid Droplets Evolved in Green Algae1[W][OA  

PubMed Central

In primitive and higher plants, intracellular storage lipid droplets (LDs) of triacylglycerols are stabilized with a surface layer of phospholipids and oleosin. In chlorophytes (green algae), a protein termed major lipid-droplet protein (MLDP) rather than oleosin on LDs was recently reported. We explored whether MLDP was present directly on algal LDs and whether algae had oleosin genes and oleosins. Immunofluorescence microscopy revealed that MLDP in the chlorophyte Chlamydomonas reinhardtii was associated with endoplasmic reticulum subdomains adjacent to but not directly on LDs. In C. reinhardtii, low levels of a transcript encoding an oleosin-like protein (oleolike) in zygotes-tetrads and a transcript encoding oleosin in vegetative cells transferred to an acetate-enriched medium were found in transcriptomes and by reverse transcription-polymerase chain reaction. The C. reinhardtii LD fraction contained minimal proteins with no detectable oleolike or oleosin. Several charophytes (advanced green algae) possessed low levels of transcripts encoding oleosin but not oleolike. In the charophyte Spirogyra grevilleana, levels of oleosin transcripts increased greatly in cells undergoing conjugation for zygote formation, and the LD fraction from these cells contained minimal proteins, two of which were oleosins identified via proteomics. Because the minimal oleolike and oleosins in algae were difficult to detect, we tested their subcellular locations in Physcomitrella patens transformed with the respective algal genes tagged with a Green Fluorescent Protein gene and localized the algal proteins on P. patens LDs. Overall, oleosin genes having weak and cell/development-specific expression were present in green algae. We present a hypothesis for the evolution of oleosins from algae to plants. PMID:23391579

Huang, Nan-Lan; Huang, Ming-Der; Chen, Tung-Ling L.; Huang, Anthony H.C.

2013-01-01

91

Biological importance of marine algae  

PubMed Central

Marine organisms are potentially prolific sources of highly bioactive secondary metabolites that might represent useful leads in the development of new pharmaceutical agents. Algae can be classified into two main groups; first one is the microalgae, which includes blue green algae, dinoflagellates, bacillariophyta (diatoms)… etc., and second one is macroalgae (seaweeds) which includes green, brown and red algae. The microalgae phyla have been recognized to provide chemical and pharmacological novelty and diversity. Moreover, microalgae are considered as the actual producers of some highly bioactive compounds found in marine resources. Red algae are considered as the most important source of many biologically active metabolites in comparison to other algal classes. Seaweeds are used for great number of application by man. The principal use of seaweeds as a source of human food and as a source of gums (phycocollides). Phycocolloides like agar agar, alginic acid and carrageenan are primarily constituents of brown and red algal cell walls and are widely used in industry. PMID:23960716

El Gamal, Ali A.

2009-01-01

92

Endosymbiotic alga from green hydra under the influence of cinoxacin.  

PubMed

Cinoxacin (Cxn) showed a strong effect on the endosymbiotic alga Chlorella; it was significantly damaged. Changes in algal color, position, structure and ultrastructure were found. In some algal cells ultrastructures were completely destroyed. The antichloroplastal and antimitochondrial effect was especially expressed. Damage to the thylakoid system of chloroplasts was more pronounced with increasing Cxn concentration. Some of the mitochondria were swollen and some of them were completely destroyed. From the evolutionary point of view, the correlation between antibacterial, and antichloroplastal and antimitochondrial effect of Cxn points to the evolutionary connection of chloroplasts and mitochondria with eubacteria. PMID:16295658

Kovacevi?, G; Kalafati?, M; Ljubesi?, N

2005-01-01

93

Origin of land plants: Do conjugating green algae hold the key?  

PubMed Central

Background The terrestrial habitat was colonized by the ancestors of modern land plants about 500 to 470 million years ago. Today it is widely accepted that land plants (embryophytes) evolved from streptophyte algae, also referred to as charophycean algae. The streptophyte algae are a paraphyletic group of green algae, ranging from unicellular flagellates to morphologically complex forms such as the stoneworts (Charales). For a better understanding of the evolution of land plants, it is of prime importance to identify the streptophyte algae that are the sister-group to the embryophytes. The Charales, the Coleochaetales or more recently the Zygnematales have been considered to be the sister group of the embryophytes However, despite many years of phylogenetic studies, this question has not been resolved and remains controversial. Results Here, we use a large data set of nuclear-encoded genes (129 proteins) from 40 green plant taxa (Viridiplantae) including 21 embryophytes and six streptophyte algae, representing all major streptophyte algal lineages, to investigate the phylogenetic relationships of streptophyte algae and embryophytes. Our phylogenetic analyses indicate that either the Zygnematales or a clade consisting of the Zygnematales and the Coleochaetales are the sister group to embryophytes. Conclusions Our analyses support the notion that the Charales are not the closest living relatives of embryophytes. Instead, the Zygnematales or a clade consisting of Zygnematales and Coleochaetales are most likely the sister group of embryophytes. Although this result is in agreement with a previously published phylogenetic study of chloroplast genomes, additional data are needed to confirm this conclusion. A Zygnematales/embryophyte sister group relationship has important implications for early land plant evolution. If substantiated, it should allow us to address important questions regarding the primary adaptations of viridiplants during the conquest of land. Clearly, the biology of the Zygnematales will receive renewed interest in the future. PMID:21501468

2011-01-01

94

The vegetative arctic freshwater green alga Zygnema is insensitive to experimental UV exposure  

Microsoft Academic Search

The physiological performance and ultrastructural integrity of the vegetative freshwater green alga Zygnema sp., growing under ambient polar day solar radiation and after exposure to experimentally low radiation, but with high UVR:PAR ratio were investigated. In the laboratory, algae were exposed to low photosynthetic active radiation (PAR=P, 400–700nm, 20?molm?2s?1), PAR+UV-A=PA (320–400nm, 4.00Wm?2=UV-A) and PAR+UV-A+UV-B=PAB (280–320nm, 0.42Wm?2=UV-B) for 24h at 7°C.

Andreas Holzinger; Michael Y. Roleda; Cornelius Lütz

2009-01-01

95

The effect of low temperature on Antarctic endolithic green algae  

NASA Technical Reports Server (NTRS)

Laboratory experiments show that undercooling to about -5 degrees C occurs in colonized Beacon sandstones of the Ross Desert, Antarctica. High-frequency temperature oscillations between 5 degrees C and -5 degrees C or -10 degrees C (which occur in nature on the rock surface) did not damage Hemichloris antarctica. In a cryomicroscope, H. antarctica appeared to be undamaged after slow or rapid cooling to -50 degrees C. 14CO2 incorporation after freezing to -20 degrees C was unaffected in H. antarctica or in Trebouxia sp. but slightly depressed in Stichococcus sp. (isolated from a less extreme Antarctic habitat). These results suggest that the freezing regime in the Antarctic desert is not injurious to endolithic algae. It is likely that the freezing-point depression inside the rock makes available liquid water for metabolic activity at subzero temperatures. Freezing may occur more frequently on the rock surface and contribute to the abiotic nature of the surface.

Meyer, M. A.; Morris, G. J.; Friedmann, E. I.

1988-01-01

96

MACROALGAL VOLUME: A SURROGATE FOR BIOMASS IN SOME GREEN ALGAE  

EPA Science Inventory

Two green algal morphotypes, filamentous species (e.g., Chaetomorpha spp.) and flattened or tubular (e.g.,Ulva spp. and Enteromorpha spp.) were collected from 63 sites within the Yaquina Bay estuary (Newport, OR) and used to compare an in situ volumetric biomass estimator to the...

97

Effect of wave exposure on morphology, attachment strength and survival of the invasive green alga Codium fragile ssp. tomentosoides  

Microsoft Academic Search

Hydrodynamic forces are a key factor influencing morphology and survival of marine algae in intertidal and shallow subtidal habitats. Since 1989, the invasive green alga Codium fragile ssp. tomentosoides has spread rapidly in Atlantic Canada, forming dense stands in intertidal pools and shallow subtidal habitats. We measured the morphology and attachment strength of Codium over 4 seasons at 3 sites

Olivier D'Amours; Robert E. Scheibling

2007-01-01

98

PRODUCTION AND NUTRITIVE VALUE OF ARTHROSPIRA PLATENSIS, A SPIRAL BLUE-GREEN ALGA GROWN ON SWINE WASTES  

Microsoft Academic Search

SUMMARY Methane generation has been proposed as a means of swine waste disposal. As a secondary treatment to recover nitrogen, carbon and other nutrients from the effluent of a methane generator, Arthrospira platensis (a blue-green alga also known as Spirulina) was grown and its nutritive value determined. This alga con- tained 55 to 61% crude protein and was easy to

Po Chung; W. G. Pond; J. M. Kingsbury; L. Krook

2010-01-01

99

Algae.  

PubMed

Algae frequently get a bad press. Pond slime is a problem in garden pools, algal blooms can produce toxins that incapacitate or kill animals and humans and even the term seaweed is pejorative - a weed being a plant growing in what humans consider to be the wrong place. Positive aspects of algae are generally less newsworthy - they are the basis of marine food webs, supporting fisheries and charismatic marine megafauna from albatrosses to whales, as well as consuming carbon dioxide and producing oxygen. Here we consider what algae are, their diversity in terms of evolutionary origin, size, shape and life cycles, and their role in the natural environment and in human affairs. PMID:25004359

Raven, John A; Giordano, Mario

2014-07-01

100

Substitution rate calibration of small subunit ribosomal RNA identifies chlorarachniophyte endosymbionts as remnants of green algae.  

PubMed

Chlorarachniophytes are amoeboid algae with chlorophyll a and b containing plastids that are surrounded by four membranes instead of two as in plants and green algae. These extra membranes form important support for the hypothesis that chlorarachniophytes have acquired their plastids by the ingestion of another eukaryotic plastid-containing alga. Chlorarachniophytes also contain a small nucleus-like structure called the nucleomorph situated between the two inner and the two outer membranes surrounding the plastid. This nucleomorph is a remnant of the endosymbiont's nucleus and encodes, among other molecules, small subunit ribosomal RNA. Previous phylogenetic analyses on the basis of this molecule provided unexpected and contradictory evidence for the origin of the chlorarachniophyte endosymbiont. We developed a new method for measuring the substitution rates of the individual nucleotides of small subunit ribosomal RNA. From the resulting substitution rate distribution, we derived an equation that gives a more realistic relationship between sequence dissimilarity and evolutionary distance than equations previously available. Phylogenetic trees constructed on the basis of evolutionary distances computed by this new method clearly situate the chlorarachniophyte nucleomorphs among the green algae. Moreover, this relationship is confirmed by transversion analysis of the Chlorarachnion plastid small subunit ribosomal RNA. PMID:8755544

Van de Peer, Y; Rensing, S A; Maier, U G; De Wachter, R

1996-07-23

101

Purification and characterization of pentagalloylglucose, and alpha-glucosidase inhibitor/antibiotic from the freshwater green alga Spirogyra varians.  

PubMed Central

An alpha-glucosidase inhibitor/antibiotic was purified from the freshwater green alga Spirogyra varians and was determined to be the pentagalloylglucose 3-O-digalloyl-1,2,6-trigalloylglucose. PMID:3145739

Cannell, R J; Farmer, P; Walker, J M

1988-01-01

102

Ulvan, a Sulfated Polysaccharide from Green Algae, Activates Plant Immunity through the Jasmonic Acid Signaling Pathway  

PubMed Central

The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway. PMID:20445752

Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérčse; Dumas, Bernard

2010-01-01

103

Ulvan, a sulfated polysaccharide from green algae, activates plant immunity through the jasmonic acid signaling pathway.  

PubMed

The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway. PMID:20445752

Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérčse; Dumas, Bernard

2010-01-01

104

ULTRASTRUCTURE OF MITOSIS AND CYTOKINESIS IN THE MULTINUCLEATE GREEN ALGA ACROSIPHONIA  

PubMed Central

The processes of mitosis and cytokinesis in the multinucleate green alga Acrosiphonia have been examined in the light and electron microscopes. The course of events in division includes thickening of the chloroplast and migration of numerous nuclei and other cytoplasmic incusions to form a band in which mitosis occurs, while other nuclei in the same cell but not in the band do not divide. Centrioles and microtubules are associated with migrated and dividing nuclei but not with nonmigrated, nondividing nuclei. Cytokinesis is accomplished in the region of the band, by means of an annular furrow which is preceded by a hoop of microtubules. No other microtubules are associated with the furrow. Characteristics of nuclear and cell division in Acrosiphonia are compared with those of other multinucleate cells and with those of other green algae. PMID:4139161

Hudson, Peggy R.; Waaland, J. Robert

1974-01-01

105

Biosynthesis of phytoquinones. Homogentisic acid: a precursor of plastoquinones, tocopherols and ?-tocopherolquinone in higher plants, green algae and blue–green algae  

PubMed Central

1. By means of 14C tracer experiments and isotope competition experiments the roles of d-tyrosine, p-hydroxyphenylpyruvic acid, p-hydroxyphenylacetic acid, phenylacetic acid, homogentisic acid and homoarbutin (2-methylquinol 4-?-d-glucoside) in the biosynthesis of plastoquinones, tocopherols and ?-tocopherolquinone by maize shoots was investigated. It was established that d-tyrosine, p-hydroxyphenylpyruvic acid and homogentisic acid can all be utilized for this purpose, whereas p-hydroxyphenylacetic acid, phenylacetic acid and homoarbutin cannot. Studies on the mode of incorporation of d-tyrosine, p-hydroxyphenylpyruvic acid and homogentisic acid showed that their nuclear carbon atoms and the side-chain carbon atom adjacent to the nucleus give rise (as a C6-C1 unit) to the p-benzoquinone rings and nuclear methyl groups (one in each case) of plastoquinone-9 and ?-tocopherolquinone and the aromatic nuclei and nuclear methyl groups (one in each case) of ?-tocopherol and ?-tocopherol. 2. By using [14C]-homogentisic acid it has been shown that homogentisic acid is also a precursor of plastoquinone, tocopherols and ?-tocopherolquinone in the higher plants Lactuca sativa and Rumex sanguineus, the green algae Chlorella pyrenoidosa and Euglena gracilis and the blue–green alga Anacystis nidulans. PMID:4986835

Whistance, G. R.; Threlfall, D. R.

1970-01-01

106

COMPLEMENTARY CHROMATIC ADAPTATION IN A FILAMENTOUS BLUE-GREEN ALGA  

PubMed Central

Fluorescent and red light environments generate greatly different patterns of pigmentation and morphology in Fremyella diplosiphon. Most strikingly, red-illuminated cultures contain no measurable C-phycoerythrin and have a mean filament length about 10 times shorter than fluorescent-illuminated cultures. C-phycoerythrin behaves as a photoinducible constituent of this alga. Spectrophotometric and immunochemical procedures were devised so that C-phycoerythrin metabolism could be studied quantitatively with [14C]-phenylalanine pulse-chased cultures. Transfer of red-illuminated cultures to fluorescent light initiates C-phycoerythrin production by essentially de novo synthesis. C-phycoerythrin is not degraded to any significant extent in cultures continuously illuminated with fluorescent light. Transfer of fluorescent-illuminated cultures to red light causes an abrupt cessation of C-phycoerythrin synthesis. The C-phycoerythrin content of cultures adapting to red light decreases and subsequently becomes constant. Loss of C-phycoerythrin is not brought about by metabolic degradation, but rather by a decrease in mean filament length which is effected by transcellular breakage. In this experimental system, light influences intracellular C-phycoerythrin levels by regulating the rate of synthesis of the chromoprotein. PMID:4199659

Bennett, Allen; Bogorad, Lawrence

1973-01-01

107

Effects of nutrients present in Bold’s basal medium on the green alga Stigeoclonium pascheri  

Microsoft Academic Search

The effects of varying concentrations of nutrients present in Bold’s basal medium on the extent of colony formation from vegetative\\u000a fragments, sporulation and spore germination of the green algaStigeoclonium poscheri were studied. A decrease of colony formation was observed in media deficient in MgSO4, NaNO3, phosphates, and containing a 10-fold increase of H3BO3. Sporulation decreased in the same media. However,

S. C. Agrawal; Y. S. R. K. Sarma

1982-01-01

108

Nitrogenase activity in the blue-green alga Plectonema boryanum strain 594  

Microsoft Academic Search

The non-heterocystous filamentous blue-green alga, Plectonema boryanum strain 594 reduces acetylene to ethylene, incorporates 15N2 into cell protoplasm, and grows readily in medium free of combined nitrogen, when incubated in a gas phase without added oxygen. Cells grown in the presence of 50 mg\\/l of ammonium-nitrogen do not reduce acetylene, and a concentration of 0.015 atm. CO in the gas

W. D. P. Stewart; M. Lex

1970-01-01

109

Growth inhibition of blue–green algae by allelopathic effects of macrophytes  

Microsoft Academic Search

Inhibitory effects of macrophytes on the growth of blue-green algae (i.e. Microcystis oeruginosa, Anoboena flos-aquae, or Phormidium tenue) were evaluated in a coexistence culture system in which concentrations of different macrophyte species were varied (i.e. Egeria densa, Cabomba caroliniana. Myriophyllutn spicatum, Ceratophyllum demersum, Eleocharis acicularis, Potamogeton oxyphyllus, Potamogeton crispus, Limnophila sessilifloro, or Vallisneria denseserrulata). Coexistence assay results showed that only

Satoshi Nakai; Yutaka Inoue; Masaaki Hosomi; Akihiko Murakami

1999-01-01

110

Regulation of phytochelatin synthesis by zinc and cadmium in marine green alga, Dunaliella tertiolecta  

Microsoft Academic Search

Although Cd2+ is a more effective inducer of phytochelatin (PC) synthesis than Zn2+ in higher plants, we have observed greater induction of PC synthesis by Zn2+ than Cd2+ in the marine green alga, Dunaliella tertiolecta. To elucidate this unique regulation of PC synthesis by Zn2+, we investigated the effects of Zn2+ and Cd2+ on the activities of both phytochelatin synthase

Naoki Tsuji; Nayumi Hirayanagi; Osamu Iwabe; Takashi Namba; Mariko Tagawa; Shiho Miyamoto; Hitoshi Miyasaka; Masahiro Takagi; Kazumasa Hirata; Kazuhisa Miyamoto

2003-01-01

111

Large arrays of tandemly repeated DNA sequences in the green alga Chlamydomonas reinhardtii  

Microsoft Academic Search

We describe the characterization of tandemly repeated DNA sequences, which resemble the satellite DNA sequences of multicellular eucaryotes, in the unicellular green alga Chlamydomonas reinhardtii. Restriction enzymes that cleave C. reinhardtii DNA relatively frequently produce a number of high molecular weight DNA fragments in addition to the bulk of low molecular weight DNA fragments. pTANC 1.5 contains a 1.5 kb

Trudy Hails; Mark Jobling; Anil Day

1993-01-01

112

Trails of Green Alga Hydrogen Research – from Hans Gaffron to New Frontiers  

Microsoft Academic Search

This paper summarizes aspects of the history of photosynthetic hydrogen research, from the pioneering discovery of Hans Gaffron\\u000a over 60 years ago to the potential exploitation of green algae in commercial H2-production. The trail started as a mere scientific curiosity, but promises to be a most important discovery, one that leads\\u000a photosynthesis research to important commercial applications. Progress achieved in

Anastasios Melis; Thomas Happe

2004-01-01

113

Class XIII myosins from the green alga Acetabularia : driving force in organelle transport and tip growth?  

Microsoft Academic Search

The green alga Acetabularia cliftonii (Dasycladales) contains at least two myosin genes, which already have been assigned class XIII of the myosin superfamily\\u000a (Cope et al., 1996, Structure 4: 969–987). Here we report a complete analysis of their gene structure and their corresponding transcripts\\u000a Aclmyol and Aclmyo2. Despite promising Northern blot data no evidence for alternative splicing could be found.

Oliver Vugrek; Heiko Sawitzky; Diedrik Menzel

2003-01-01

114

EFFECT OF BLUE GREEN MICRO ALGAE (SPIRULINA) ON COCOON QUANTITATIVE PARAMETERS OF SILKWORM (Bombyx mori L.)  

Microsoft Academic Search

Spirulina is blue-green micro algae. It contains 18 amino acids and vital vitamins like biotin, tocopherol, thiamine, riboflavin, niacin, folic acid, pyrodozoic acid, beta-carotene and vitamin B12 etc. These nutrients which are very easy to digest protein (biliprotein), carbohydrates (mucopolysaccharides, rhamnose and glycogen), 50 different minerals and trace minerals, beta-carotene, chlorophyll, GLA omega-3 fatty acid, and many other nutrients found

Dhiraj Kumar; Ashutosh Kumar; S. S. Dhami

115

Purification and characterization of phycocyanin from the blue-green alga Aphanizomenon flos-aquae  

Microsoft Academic Search

Aphanizomenon flos-aquae (AFA) is a blue-green alga and represents a nutrient-dense food source. In this study the presence of phycocyanin (PC), a blue protein belonging to the photosynthetic apparatus, has been demonstrated in AFA. An efficient method for its separation has been set up: PC can be purified by a simple single step chromatographic run using a hydroxyapatite column (ratio

Serena Benedetti; Sara Rinalducci; Francesca Benvenuti; Sonia Francogli; Silvia Pagliarani; Luca Giorgi; Mauro Micheloni; Gian Maria D’Amici; Lello Zolla; Franco Canestrari

2006-01-01

116

Phylogenetic analysis identifies the invertebrate pathogen Helicosporidium sp. as a green alga (Chlorophyta).  

PubMed

Historically, the invertebrate pathogens of the genus Helicosporidium were considered to be either protozoa or fungi, but the taxonomic position of this group has not been considered since 1931. Recently, a Helicosporidium sp., isolated from the blackfly Simulium jonesi Stone & Snoddy (Diptera: Simuliidae), has been amplified in the heterologous host Helicoverpa zea. Genomic DNA has been extracted from gradient-purified cysts. The 185, 28S and 5.8S regions of the Helicosporidium rDNA, as well as partial sequences of the actin and beta-tubulin genes, were amplified by PCR and sequenced. Comparative analysis of these nucleotide sequences was performed using neighbour-joining and maximum-parsimony methods. All inferred phylogenetic trees placed Helicosporidium sp. among the green algae (Chlorophyta), and this association was supported by bootstrap and parsimony jackknife values. Phylogenetic analysis focused on the green algae depicted Helicosporidium sp. as a close relative of Prototheca wickerhamii and Prototheca zopfii (Chlorophyta, Trebouxiophyceae), two achlorophylous, pathogenic green algae. On the basis of this phylogenetic analysis, Helicosporidium sp. is clearly neither a protist nor a fungus, but appears to be the first described algal invertebrate pathogen. These conclusions lead us to propose the transfer of the genus Helicosporidium to Chlorophyta, Trebouxiophyceae. PMID:11837312

Tartar, Aurélien; Boucias, Drion G; Adams, Byron J; Becnel, James J

2002-01-01

117

BROWN ALGAE Colpomenia sinuosa  

E-print Network

BROWN ALGAE Colpomenia sinuosa GREEN ALGAE Dictyosphaeria cavernosa Amphiroa fragilissima Gelidiopsis intricata Botryocladia pyriformis RED ALGAE CYANOBACTERIA Oscillitoria acuminata Schizothrix sp. "ALGAE"­ A DIVERSE ASSORTMENT OF LIFE FORMS Photosynthesis is performed by a taxonomically diverse

Sullivan, Matthew B.

118

Impact of green algae on the measurement of Microcystis aeruginosa populations in lagoon-treated wastewater with an algae online analyser.  

PubMed

Tests on the algae online analyser (AOA) showed that there was a strong direct linear correlation between cell density and in vivo Chl-a concentration for M. aeruginosa over the range of interest for a biologically treated effluent at a wastewater treatment plant (25,000-65,000?cells?mL(-1), equivalent to a biovolume of 2-6?mm(3?)L(-1)). However, the AOA can provide an overestimate or underestimate of M. aeruginosa populations when green algae are present in the effluent, depending on their species and relative numbers. The results from this study demonstrated that the green algae (e.g., Euglena gracilis, Chlorella sp.) in the field phytoplankton population should be considered during calibration. In summary, the AOA has potential for use as an alert system for the presence of M. aeruginosa, and thus potentially of cyanobacterial blooms, in wastewater stabilization ponds. PMID:25204421

Nguyen, Thang; Roddick, Felicity A; Fan, Linhua

2015-03-01

119

Expulsion of Symbiotic Algae during Feeding by the Green Hydra – a Mechanism for Regulating Symbiont Density?  

PubMed Central

Background Algal-cnidarian symbiosis is one of the main factors contributing to the success of cnidarians, and is crucial for the maintenance of coral reefs. While loss of the symbionts (such as in coral bleaching) may cause the death of the cnidarian host, over-proliferation of the algae may also harm the host. Thus, there is a need for the host to regulate the population density of its symbionts. In the green hydra, Chlorohydra viridissima, the density of symbiotic algae may be controlled through host modulation of the algal cell cycle. Alternatively, Chlorohydra may actively expel their endosymbionts, although this phenomenon has only been observed under experimentally contrived stress conditions. Principal Findings We show, using light and electron microscopy, that Chlorohydra actively expel endosymbiotic algal cells during predatory feeding on Artemia. This expulsion occurs as part of the apocrine mode of secretion from the endodermal digestive cells, but may also occur via an independent exocytotic mechanism. Significance Our results demonstrate, for the first time, active expulsion of endosymbiotic algae from cnidarians under natural conditions. We suggest this phenomenon may represent a mechanism whereby cnidarians can expel excess symbiotic algae when an alternative form of nutrition is available in the form of prey. PMID:18596972

Fishman, Yelena; Zlotkin, Eliahu; Sher, Daniel

2008-01-01

120

Evaluation of antigenotoxic effects of carotenoids from green algae Chlorococcum humicola using human lymphocytes  

PubMed Central

Objective To identify the available phytochemicals and carotenoids in the selected green algae and evaluate the potential genotoxic/antigenotoxic effect using lymphocytes. Methods Organic solvent extracts of Chlorococcum humicola (C. humicola) were used for the phytochemical analysis. The available carotenoids were assessed by HPLC, and LC-MS analysis. The genotoxicity was induced by the benzo(a)pyrene in the lymphocyte culture, the genotoxic and antigenotoxic effects of algal carotenoids with and without genotoxic inducer were evaluated by chromosomal aberration (CA), sister chromatid exchange (SCE) and micronucleus assay (MN). Results The results of the analysis showed that the algae were rich in carotenoids and fatty acids. In the total carotenoids lutein, ?-carotene and ?-carotene were found to be present in higher concentration. The frequency of CA and SCE increased by benzo(a)pyrene were significantly decreased by the carotenoids (P<0.05 for CA, P<0.001 for SCE). The MN frequencies of the cells were significantly decreased by the treatment with carotenoids when compared with the positive controls (P<0.05). Conclusions The findings of the present study demonstrate that, the green algae C. humicola is a rich source of bioactive compounds especially carotenoids which effectively fight against environmental genotoxic agents, the carotenoids itself is not a genotoxic substance and should be further considered for its beneficial effects. PMID:23569879

Bhagavathy, S; Sumathi, P

2012-01-01

121

Identification of phytochelatins in the cadmium-stressed conjugating green alga Micrasterias denticulata.  

PubMed

Aquatic environments like peat bogs are affected by anthropogenic metal input into the environment. These ecosystems are inhabited by unicellular green algae of the class Zygnematophyceae. In this study the desmid Micrasterias denticulata was stressed with 600 nM Cd, 10 ?M Cr and 300 nM Cu for 3 weeks. GSH levels were measured with HPLC and did not differ between the different treatments or the control. According to the metallo-thiolomics concept, mass spectrometry was used as a method for unambiguous thiol peptide identification. PC2, PC3 and PC4 were clearly identified in the Cd stressed sample with UPLC-MS by their MS spectrum and molecular masses. PC2 and PC3 were determined to be the main thiol compounds, while PC4 was only abundant in traces in Micrasterias. In addition, the identity of PC2 and PC3 was confirmed by MS/MS. No PCs were detected in the Cu stressed algae sample. However, in the Cr stressed sample traces of PC2 were indicated by a peak in UPLC-MS at the retention time of the PC2 standard, but the intensity was too low to acquire reliable MS and MS/MS spectra. In this study PCs have been detected for the first time in a green alga of the division Streptophyta, a close relative to higher plants. PMID:23266414

Volland, Stefanie; Schaumlöffel, Dirk; Dobritzsch, Dirk; Krauss, Gerd-Joachim; Lütz-Meindl, Ursula

2013-04-01

122

Experimental Studies on Sexual Reproduction in Diatoms  

Microsoft Academic Search

The diatoms are the most speciose group of algae, having global ecological significance in the carbon and silicon cycles. They are almost unique among algae in being diplontic, and sexual reproduction is an obligate stage in the life cycle of most diatom species. It is unclear which are the principal factors that have fostered the evolutionary success of diatoms, but

Victor A. Chepurnov; David G. Mann; Koen Sabbe; Wim Vyverman

2004-01-01

123

Carbon acquisition by diatoms  

Microsoft Academic Search

Diatoms are responsible for up to 40% of primary productivity in the ocean, and complete genome sequences are available for\\u000a two species. However, there are very significant gaps in our understanding of how diatoms take up and assimilate inorganic\\u000a C. Diatom plastids originate from secondary endosymbiosis with a red alga and their Form ID Rubisco (ribulose-1,5-bisphosphate\\u000a carboxylase-oxygenase) from horizontal gene

Karen Roberts; Espen Granum; Richard C. Leegood; John A. Raven

2007-01-01

124

DNA barcoding of a new record of epi-endophytic green algae Ulvella leptochaete (Ulvellaceae, Chlorophyta) in India.  

PubMed

Epi-endophytic green algae comprise one of the most diverse and phylogenetically primitive groups of green algae and are considered to be ubiquitous in the world's oceans; however, no reports of these algae exist from India. Here we report the serendipitous discovery of Ulvella growing on intertidal green algae Cladophora glomerata and benthic red algae Laurencia obtusa collected from India. DNA barcodes at nuclear ribosomal DNA Internal Transcriber Spacer (nrDNA ITS) 1 and 2 regions for Indian isolates from the west and east coasts have been generated for the first time. Based on morphology and DNA barcoding, isolates were identified as Ulvella leptochaete. Phylogenetic reconstruction of concatenated dataset using Maximum Likelihood method differentiated Indian isolates from other accessions of this alga available in Genbank, albeit with low bootstrap support. Monophyly of Ulvella leptochaete was obvious in both of our phylogenetic analyses. With this first report of epi-endophytic algae from Indian territorial waters, the dire need to catalogue its cryptic diversity is highlighted and avenues of future research are discussed. PMID:25116625

Bast, Felix; Bhushan, Satej; John, Aijaz Ahmad

2014-09-01

125

A Lack of Parasitic Reduction in the Obligate Parasitic Green Alga Helicosporidium  

PubMed Central

The evolution of an obligate parasitic lifestyle is often associated with genomic reduction, in particular with the loss of functions associated with increasing host-dependence. This is evident in many parasites, but perhaps the most extreme transitions are from free-living autotrophic algae to obligate parasites. The best-known examples of this are the apicomplexans such as Plasmodium, which evolved from algae with red secondary plastids. However, an analogous transition also took place independently in the Helicosporidia, where an obligate parasite of animals with an intracellular infection mechanism evolved from algae with green primary plastids. We characterised the nuclear genome of Helicosporidium to compare its transition to parasitism with that of apicomplexans. The Helicosporidium genome is small and compact, even by comparison with the relatively small genomes of the closely related green algae Chlorella and Coccomyxa, but at the functional level we find almost no evidence for reduction. Nearly all ancestral metabolic functions are retained, with the single major exception of photosynthesis, and even here reduction is not complete. The great majority of genes for light-harvesting complexes, photosystems, and pigment biosynthesis have been lost, but those for other photosynthesis-related functions, such as Calvin cycle, are retained. Rather than loss of whole function categories, the predominant reductive force in the Helicosporidium genome is a contraction of gene family complexity, but even here most losses affect families associated with genome maintenance and expression, not functions associated with host-dependence. Other gene families appear to have expanded in response to parasitism, in particular chitinases, including those predicted to digest the chitinous barriers of the insect host or remodel the cell wall of Helicosporidium. Overall, the Helicosporidium genome presents a fascinating picture of the early stages of a transition from free-living autotroph to parasitic heterotroph where host-independence has been unexpectedly preserved. PMID:24809511

Pombert, Jean-François; Blouin, Nicolas Achille; Lane, Chris; Boucias, Drion; Keeling, Patrick J.

2014-01-01

126

A lack of parasitic reduction in the obligate parasitic green alga Helicosporidium.  

PubMed

The evolution of an obligate parasitic lifestyle is often associated with genomic reduction, in particular with the loss of functions associated with increasing host-dependence. This is evident in many parasites, but perhaps the most extreme transitions are from free-living autotrophic algae to obligate parasites. The best-known examples of this are the apicomplexans such as Plasmodium, which evolved from algae with red secondary plastids. However, an analogous transition also took place independently in the Helicosporidia, where an obligate parasite of animals with an intracellular infection mechanism evolved from algae with green primary plastids. We characterised the nuclear genome of Helicosporidium to compare its transition to parasitism with that of apicomplexans. The Helicosporidium genome is small and compact, even by comparison with the relatively small genomes of the closely related green algae Chlorella and Coccomyxa, but at the functional level we find almost no evidence for reduction. Nearly all ancestral metabolic functions are retained, with the single major exception of photosynthesis, and even here reduction is not complete. The great majority of genes for light-harvesting complexes, photosystems, and pigment biosynthesis have been lost, but those for other photosynthesis-related functions, such as Calvin cycle, are retained. Rather than loss of whole function categories, the predominant reductive force in the Helicosporidium genome is a contraction of gene family complexity, but even here most losses affect families associated with genome maintenance and expression, not functions associated with host-dependence. Other gene families appear to have expanded in response to parasitism, in particular chitinases, including those predicted to digest the chitinous barriers of the insect host or remodel the cell wall of Helicosporidium. Overall, the Helicosporidium genome presents a fascinating picture of the early stages of a transition from free-living autotroph to parasitic heterotroph where host-independence has been unexpectedly preserved. PMID:24809511

Pombert, Jean-François; Blouin, Nicolas Achille; Lane, Chris; Boucias, Drion; Keeling, Patrick J

2014-05-01

127

A new model for the calcification of the green macro-alga Halimeda opuntia (Lamouroux)  

NASA Astrophysics Data System (ADS)

Halimeda opuntia is a cosmopolitan marine calcifying green alga in shallow tropical marine environments. Besides Halimeda's contribution to a diverse habitat, the alga is an important sediment producer. Fallen calcareous segments of Halimeda spp. are a major component of carbonate sediments in many tropical settings and play an important role in reef framework development and carbonate platform buildup. Consequently the calcification of H. opuntia accounts for large portions of the carbonate budget in tropical shallow marine ecosystems. Earlier studies investigating the calcification processes of Halimeda spp. have tended to focus on the microstructure or the physiology of the alga, thus overlooking the interaction of physiological and abiotic processes behind the formation of the skeleton. By analyzing microstructural skeletal features of Halimeda segments with the aid of scanning electron microscopy and relating their occurrence to known physiological processes, we have been able to identify the initiation of calcification within an organic matrix and demonstrate that biologically induced cementation is an important process in calcification. For the first time, we propose a model for the calcification of Halimeda spp. that considers both the alga's physiology and the carbon chemistry of the seawater with respect to the development of different skeletal features. The presence of an organic matrix and earlier detected external carbonic anhydrase activity suggest that Halimeda spp. exhibit biotic precipitation of calcium carbonate, as many other species of marine organisms do. On the other hand, it is the formation of micro-anhedral carbonate through the alga's metabolism that leads to a cementation of living segments. Precisely, this process allows H. opuntia to contribute substantial amounts of carbonate sediments to tropical shallow seas.

Wizemann, André; Meyer, Friedrich W.; Westphal, Hildegard

2014-12-01

128

Photosynthetic biomanufacturing in green algae; production of recombinant proteins for industrial, nutritional, and medical uses.  

PubMed

Recombinant proteins are widely used for industrial, nutritional, and medical applications. Green microalgae have attracted considerable attention recently as a biomanufacturing platform for the production of recombinant proteins for a number of reasons. These photosynthetic eukaryotic microorganisms are safe, scalable, easy to genetically modify through transformation, mutagenesis, or breeding, and inexpensive to grow. Many microalgae species are genetically transformable, but the green alga Chlamydomonas reinhardtii is the most widely used host for recombinant protein expression. An extensive suite of molecular genetic tools has been developed for C. reinhardtii over the last 25 years, including a fully sequenced genome, well-established methods for transformation, mutagenesis and breeding, and transformation vectors for high levels of recombinant protein accumulation and secretion. Here, we review recent successes in the development of C. reinhardtii as a biomanufacturing host for recombinant proteins, including antibodies and immunotoxins, hormones, industrial enzymes, an orally-active colostral protein for gastrointestinal health, and subunit vaccines. In addition, we review the biomanufacturing potential of other green algae from the genera Dunaliella and Chlorella. PMID:24659086

Rasala, Beth A; Mayfield, Stephen P

2015-03-01

129

Photosynthetic unit size, carotenoids, and chlorophyll—protein composition of Prochloron sp., a prokaryotic green alga  

PubMed Central

Six samples of the prokaryotic, unicellular algae Prochloron sp., which occur in association with didemnid ascidians, were collected from various localities in the tropical Pacific Ocean, and their pigments and chlorophyll-protein complexes were identified and characterized. No phycobilin pigments were detected in any of the species. Chlorophylls a and b were present in ratios of a/b = 4.4-6.9. The major carotenoids were ?-carotene (70%) and zeaxanthin (20%). Minor carotenoids of one isolate were identified as echinenone, cryptoxanthin, isocryptoxanthin, mutachrome, and trihydroxy-?-carotene; no ?-ring carotenoids were found in any sample. Except for the absence of glycosidic carotenoids, the overall pigment composition is typical of cyanobacteria. A chlorophyll a/b-protein complex was present in Prochloron; it was electrophoretically and spectrally indistinguishable from the light-harvesting chlorophyll a/b-protein of higher plants and green algae. It accounted for 26% (compared to ?50% in green plants) of the total chlorophyll; 17% was associated with a P700-chlorophyll a-protein. The photosynthetic unit size of 240 ± 10 chlorophylls per P700 in Prochloron was about half that of eukaryotic green plants. A model is proposed for the in vivo organization of chlorophyll in Prochloron. PMID:16592528

Withers, Nancy W.; Alberte, Randall S.; Lewin, Ralph A.; Thornber, J. Philip; Britton, George; Goodwin, Trevor W.

1978-01-01

130

Reproduction-related effects of green alga Coccomyxa sp. infestation in the horse mussel Modiolus modiolus.  

PubMed

The effects of Coccomyxa sp. infestation on the reproductive characteristics of the horse mussel Modiolus modiolus from the north-western Pacific (Peter the Great Bay, Sea of Japan) are demonstrated in this study. The mussels were collected monthly from May to September of 2009, and the prevalence of females and males with green tissues was 39% and 47%, respectively. Overall, the green alga infection caused a mild effect on gametogenesis in the horse mussel. The dynamics of gonad development in the healthy and infected mussels during the study period was generally similar, with the spawning being partial and occurring from the beginning of June to the first half of September; total spawning was recorded at the end of this period. However, several negative reproduction-related effects of the green alga infestation were observed, i.e., general gonadal underdevelopment, which was apparent from significant decrease in the acinus areas of the ovaries and testes and an increase in the connective tissue layer between the acini, a delay in some stages of the reproductive cycle and production of decreased number of spermatozoa and large vitellogenic oocytes, especially in the early spawning period (June). All of these results suggest a reduced reproductive output for the infected mussels. PMID:23439265

Vaschenko, M A; Kovaleva, A L; Syasina, I G; Kukhlevsky, A D

2013-05-01

131

Inhibitory effects of terpene alcohols and aldehydes on growth of green alga Chlorella pyrenoidosa  

SciTech Connect

The growth of the green alga Chlorella pyrenoidosa was inhibited by terpene alcohols and the terpene aldehyde citral. The strongest activity was shown by citral. Nerol, geraniol, and citronellol also showed pronounced activity. Strong inhibition was linked to acyclic terpenes containing a primary alcohol or aldehyde function. Inhibition appeared to be taking place through the vapor phase rather than by diffusion through the agar medium from the terpene-treated paper disks used in the system. Inhibition through agar diffusion was shown by certain aged samples of terpene hydrocarbons but not by recently purchased samples.

Ikawa, Miyoshi; Mosley, S.P.; Barbero, L.J. (Univ. of New Hampshire, Durham (United States))

1992-10-01

132

Proteasome and NF-kappaB inhibiting phaeophytins from the green alga Cladophora fascicularis.  

PubMed

Chemical examination of the green alga Cladophora fascicularis resulted in the isolation and characterization of a new porphyrin derivative, porphyrinolactone (1), along with five known phaeophytins 2-6 and fourteen sterols and cycloartanes. The structure of 1 was determined on the basis of spectroscopic analyses and by comparison of its NMR data with those of known phaeophytins. Compounds 1-6 displayed moderate inhibition of tumor necrosis factor alpha (TNF-alpha) induced nuclear factor-kappaB (NF-kappaB) activation, while 2 and 4 displayed potential inhibitory activity toward proteasome chymotripsin-like activation. The primary structure-activity relationship was also discussed. PMID:17851413

Huang, Xinping; Li, Min; Xu, Bo; Zhu, Xiaobin; Deng, Zhiwei; Lin, Wenhan

2007-01-01

133

Lipids of membranes and of the cell envelope in heterocysts of a blue-green alga.  

PubMed

Heterocysts of Anabaena cylindrica, isolated rapidly in the cold, were found-in contrast to earlier reports-to contain all of the same lipids and lipophilic pigments, and in about the same proportions, as vegetative cells. In broken filaments and in heterocysts damaged during isolation, the membrane lipids and certain pigments (myxoxanthophyll and an unidentified red pigment) break down rapidly. The glycolipids specific to heterocyst-forming blue-green algae are localized in the laminated layer of the heterocyst envelope. A possible role of the laminated layer is discussed. PMID:24477350

Winkenbach, F; Wolk, C P; Jost, M

1972-03-01

134

Chemical composition, in vitro protein digestibility and in vitro available iron of blue green alga, Nostoc commune  

Microsoft Academic Search

Blue-green alga,Nostoc commune, contained moderate amounts of protein and iron. Itsin vitro protein digestibility was 43–50%. The soluble and ionic iron from the alga was extractable to some extent at pH 1.5 but was not detectable at pH 8.0. The digestion by protease did not affect the iron detection. Heat processing at 100 and 120°C failed to increase the digestibility

Kohji Hori; Tomoko Ueno-Mohri; Takuo Okita; Genji Ishibashi

1990-01-01

135

In Vivo Characterization of the Electrochemical Proton Gradient Generated in Darkness in Green Algae and Its Kinetic Effects on Cytochrome b6f Turnover  

E-print Network

Algae and Its Kinetic Effects on Cytochrome b6f Turnover Giovanni Finazzi*, and Fabrice Rappaport CNRSV) fits well with estimations based on the ATP/ADP ratio measured in green algae under the same conditions dark incubation of algae, the electrochemical transmembrane potential is determined only

136

A comparison of the role of two blue-green algae in THM and HAA formation.  

PubMed

The contribution of two blue-green algae species, Anabaena flos-aquae and Microcystis aeruginosa, to the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) was investigated. The experiments examined the formation potential of these disinfection by-products (DBPs) from both algae cells and extracellular organic matter (EOM) during four algal growth phases. Algal cells and EOM of Anabaena and Microcystis exhibited a high potential for DBP formation. Yields of total THMs (TTHM) and total HAAs (THAA) were closely related to the growth phase. Reactivity of EOM from Anabaena was slightly higher than corresponding cells, while the opposite result was found for Microcystis. Specific DBP yields (yield/unit C) of Anabaena were in the range of 2-11micromol/mmol C for TTHM and 2-17micromol/mmol C for THAA, while those of Microcystis were slightly higher. With regard to the distributions of individual THM and HAA compounds, differences were observed between the algae species and also between cells and EOM. The presence of bromide shifted the dominant compounds from HAAs to THMs. PMID:19457536

Huang, J; Graham, N; Templeton, M R; Zhang, Y; Collins, C; Nieuwenhuijsen, M

2009-07-01

137

Structural characterization of toxic cyclic peptides from blue-green algae by tandem mass spectrometry.  

PubMed Central

Combined use of chemical degradation, derivatization, and tandem mass spectrometry for rapid structural characterization of toxic cyclic peptides from blue-green algae at the nanomole level is described. Previously, all blue-green algal toxins were thought to belong to a family of seven-residue cyclic peptides, having the general structure cyclo-D-Ala-L-Xaa-erythro-beta-methyl-D-isoaspartic acid-L-Yaa-Adda-D-isoglutamic acid-N-methyldehydroalanine, where Xaa and Yaa represent variable amino acids of the L configuration and Adda is 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid. Structural characterization of two additional toxins indicates that further variability can exist within this family of naturally occurring toxic cyclic peptides. Isoaspartic acid and dehydroalanine can substitute for beta-methylisoaspartic acid and N-methyldehydroalanine, respectively. PMID:2492662

Krishnamurthy, T; Szafraniec, L; Hunt, D F; Shabanowitz, J; Yates, J R; Hauer, C R; Carmichael, W W; Skulberg, O; Codd, G A; Missler, S

1989-01-01

138

Toxicity and bioaccumulation kinetics of arsenate in two freshwater green algae under different phosphate regimes.  

PubMed

In the present study, the toxicity and bioaccumulation kinetics of arsenate in two green algae Chlamydomonas reinhardtii and Scenedesmus obliquus under phosphate-enriched (+P) and limited (-P) conditions were investigated. P-limitation was found to aggravate arsenate toxicity and S. obliquus was more tolerant than C. reinhardtii. Such phosphate-condition-dependent or algal-species-specific toxicity difference was narrowed when the relative inhibition of cell growth was plotted against intracellular arsenate content instead of its extracellular concentration. The discrepance was further reduced when the intracellular ratio of arsenic to phosphorus was applied. It suggests that both arsenate bioaccumulation and intracellular phosphorus played an important role in arsenate toxicity. On the other hand, arsenate uptake was induced by P-limitation and its variation with ambient arsenate concentration could be well fitted to the Michaelis-Menten model. Arsenate transporters of S. obliquus were found to have a higher affinity but lower capacity than those of C. reinhardtii, which explains its better regulation of arsenate accumulation than the latter species in the toxicity experiment. Further, arsenate depuration was facilitated and more was transformed to arsenite in C. reinhardtii or under -P condition. Intracellular proportion of arsenite was also increased after the algae were transferred from the long-term uptake media to a relatively clean solution in the efflux experiment. Both phenomena imply that algae especially the sensitive species could make physiological adjustments to alleviate the adverse effects of arsenate. Overall, our findings will facilitate the application of algae in arsenate remediation. PMID:23497978

Wang, Ning-Xin; Li, Yan; Deng, Xi-Hai; Miao, Ai-Jun; Ji, Rong; Yang, Liu-Yan

2013-05-01

139

Biochemical Basis of Obligate Autotrophy in Blue-Green Algae and Thiobacilli  

PubMed Central

Differential rates of incorporation of sugars, organic acids, and amino acids during autotrophic growth of several blue-green algae and thiobacilli have been determined. In obligate autotrophs (both blue-green algae and thiobacilli), exogenously furnished organic compounds make a very small contribution to cellular carbon; acetate, the most readily incorporated compound of those studied, contributes about 10% of newly synthesized cellular carbon. In Thiobacillus intermedius, a facultative chemoautotroph, acetate contributes over 40% of newly synthesized cellular carbon, and succinate and glutamate almost 90%. In the obligate autotrophs, carbon from pyruvate, acetate, and glutamate is incorporated into restricted groups of cellular amino acids, and the patterns of incorporation in all five organisms are essentially identical. These patterns suggest that the tricarboxylic acid cycle is blocked at the level of ?-ketoglutarate oxidation. Enzymatic analyses confirmed the absence of ?-ketoglutarate dehydrogenase in the obligate autotrophs, and also revealed that they lacked reduced nicotinamide adenine dinucleotide oxidase, and had extremely low levels of malic and succinic dehydrogenase. These enzymatic deficiencies were not manifested by the two facultative chemoautotrophs examined. On the basis of the data obtained, an interpretation of obligate autotrophy in both physiological and evolutionary terms has been developed. PMID:4963789

Smith, Arnold J.; London, Jack; Stanier, Roger Y.

1967-01-01

140

Structural characterization and anticoagulant activity of a sulfated polysaccharide from the green alga Codium divaricatum.  

PubMed

A sulfated polysaccharide, designated CP2-1, was isolated from the green alga Codium divaricatum by water extraction and purified by anion-exchange and size-exclusion chromatography. CP2-1 is a galactan which is highly sulfated and substituted with pyruvic acid ketals. On the basis of chemical and spectroscopic analyses, the backbone of CP2-1 was mainly composed of (1?3)-?-d-galactopyranose residues, branched by single (1?)-?-d-galactopyranose units attached to the main chain at C-4 positions. The degree of branching was estimated to be about 12.2%. Sulfate groups were at C-4 of (1?3)-?-d-galactopyranose and C-6 of non-reducing terminal galactose residues. In addition, the ketals of pyruvic acid were found at 3,4- of non-reducing terminal galactose residues forming a five-membered ring. CP2-1 possessed a high anticoagulant activity as assessed by the activated partial thromboplastin time and thrombin time assays. The investigation demonstrated that CP2-1 was an anticoagulant-active sulfated polysaccharide distinguishing from other sulfated polysaccharides from marine green algae. PMID:25659687

Li, Na; Mao, Wenjun; Yan, Mengxia; Liu, Xue; Xia, Zheng; Wang, Shuyao; Xiao, Bo; Chen, Chenglong; Zhang, Lifang; Cao, Sujian

2015-05-01

141

A novel ether-linked phytol-containing digalactosylglycerolipid in the marine green alga, Ulva pertusa.  

PubMed

Galactosylglycerolipids (GGLs) and chlorophyll are characteristic components of chloroplast in photosynthetic organisms. Although chlorophyll is anchored to the thylakoid membrane by phytol (tetramethylhexadecenol), this isoprenoid alcohol has never been found as a constituent of GGLs. We here described a novel GGL, in which phytol was linked to the glycerol backbone via an ether linkage. This unique GGL was identified as an Alkaline-resistant and Endogalactosylceramidase (EGALC)-sensitive GlycoLipid (AEGL) in the marine green alga, Ulva pertusa. EGALC is an enzyme that is specific to the R-Gal?/?1-6Gal?1-structure of galactolipids. The structure of U. pertusa AEGL was determined following its purification to 1-O-phytyl-3-O-Gal?1-6Gal?1-sn-glycerol by mass spectrometric and nuclear magnetic resonance analyses. AEGLs were ubiquitously distributed in not only green, but also red and brown marine algae; however, they were rarely detected in terrestrial plants, eukaryotic phytoplankton, or cyanobacteria. PMID:25157808

Ishibashi, Yohei; Nagamatsu, Yusuke; Miyamoto, Tomofumi; Matsunaga, Naoyuki; Okino, Nozomu; Yamaguchi, Kuniko; Ito, Makoto

2014-10-01

142

The charophycean green algae provide insights into the early origins of plant cell walls.  

PubMed

Numerous evolutionary innovations were required to enable freshwater green algae to colonize terrestrial habitats and thereby initiate the evolution of land plants (embryophytes). These adaptations probably included changes in cell-wall composition and architecture that were to become essential for embryophyte development and radiation. However, it is not known to what extent the polymers that are characteristic of embryophyte cell walls, including pectins, hemicelluloses, glycoproteins and lignin, evolved in response to the demands of the terrestrial environment or whether they pre-existed in their algal ancestors. Here we show that members of the advanced charophycean green algae (CGA), including the Charales, Coleochaetales and Zygnematales, but not basal CGA (Klebsormidiales and Chlorokybales), have cell walls that are comparable in several respects to the primary walls of embryophytes. Moreover, we provide both chemical and immunocytochemical evidence that selected Coleochaete species have cell walls that contain small amounts of lignin or lignin-like polymers derived from radical coupling of hydroxycinnamyl alcohols. Thus, the ability to synthesize many of the components that characterize extant embryophyte walls evolved during divergence within CGA. Our study provides new insight into the evolutionary window during which the structurally complex walls of embryophytes originated, and the significance of the advanced CGA during these events. PMID:21707800

Sřrensen, Iben; Pettolino, Filomena A; Bacic, Antony; Ralph, John; Lu, Fachuang; O'Neill, Malcolm A; Fei, Zhangzhun; Rose, Jocelyn K C; Domozych, David S; Willats, William G T

2011-10-01

143

Cell death in the unicellular green alga Micrasterias upon H2O2 induction  

PubMed Central

In the present study we investigate whether the unicellular green alga Micrasterias denticulata is capable of executing programmed cell death (PCD) upon experimental induction and by which morphological, molecular and physiological hallmarks it is characterized. This is particularly interesting as unicellular fresh water green algae growing in shallow bog ponds are exposed to extreme environmental conditions and the capability to perform PCD may provide an important strategy to guarantee survival of the population. The theoretically “immortal” alga Micrasterias is an ideal object for such investigations as it has served as a cell biological model system since many years and details on its growth properties, physiology and ultrastructure throughout the cell cycle are well known. Treatment with low concentrations of H2O2 known to induce PCD in other organisms resulted in severe ultrastructural changes of organelles as observed in TEM. These include deformation and partly disintegration of mitochondria, abnormal dilatation of cisternal rims of dictyosomes, the occurrence of multivesicular bodies, an increase in the number of ER compartments and slight condensation of chromatin. Additionally, a statistically significant increase in caspase-3-like activity could be detected which was abrogated by a caspase-3 inhibitor. Photosynthetic activity measured by fast chlorophyll fluorescence decreased as a consequence of H2O2 exposure whereas pigment composition, except of a reduction in carotenoids, was the same as in untreated controls. TUNEL positive staining and ladder-like degradation of DNA, both frequently regarded as PCD hallmark in higher plants could only be detected in dead Micrasterias cells. PMID:18950431

Darehshouri, Anza; Affenzeller, Matthias; Lütz-Meindl, Ursula

2010-01-01

144

Growth and Metabolism of the Green Alga, Chlorella Pyrenoidosa, in Simulated Microgravity  

NASA Technical Reports Server (NTRS)

The effect of microgravity on living organisms during space flight has been a topic of interest for some time, and a substantial body of knowledge on the subject has accumulated. Despite this, comparatively little information is available regarding the influence of microgravity on algae, even though it has been suggested for long duration flight or occupancy in space that plant growth systems, including both higher plants and algae, are likely to be necessary for bioregenerative life support systems. High-Aspect-Ratio Rotating-Wall Vessel or HARV bioreactors developed at Johnson Space Center provide a laboratory-based approach to investigating the effects of microgravity on cellular reactions. In this study, the HARV bioreactor was used to examine the influence of simulated microgravity on the growth and metabolism of the green alga, Chlorella pyrenoidosa. After the first 2 days of culture, cell numbers increased more slowly in simulated microgravity than in the HARV gravity control; after 7 days, growth in simulated microgravity was just over half (58%) that of the gravity control and at 14 days it was less than half (42%). Chlorophyll and protein were also followed as indices of cell competence and function; as with growth, after 2-3 days, protein and chlorophyll levels were reduced in modeled microgravity compared to gravity controls. Photosynthesis is a sensitive biochemical index of the fitness of photosynthetic organisms; thus, CO2-dependent O2 evolution was tested as a measure of photosynthetic capacity of cells grown in simulated microgravity. When data were expressed with respect to cell number, modeled microgravity appeared to have little effect on CO2 fixation. Thus, even though the overall growth rate was lower for cells cultured in microgravity, the photosynthetic capacity of the cells appears to be unaffected. Cells grown in simulated microgravity formed loose clumps or aggregates within about 2 days of culture, with aggregation increasing over time. Presently, the basis for, or significance of, the cell aggregation is unknown. The results from this study suggest that cell growth and morphological characteristics of green algae may be altered by culture in simulated microgravity. The data obtained to date should provide a solid basis for additional experimentation regarding the influence of modeled microgravity on cell morphology, physiological activity, protein production and possibly gene expression in algal and plant cell systems. The final aim of the study is to provide useful information to elucidate the underlying mechanism for the biological effects of microgravity on cells.

Mills, W. Ronald

2003-01-01

145

Structure and interactions of ulvan in the cell wall of the marine green algae Ulva rotundata (Ulvales, Chlorophyceae)  

Microsoft Academic Search

Ulvan, the sulfated cell-wall polysaccharides from green seaweeds (Ulva species), presents structural and functional properties of interest for different applications. Its extraction yield in water varies depending on the species, the period of collect and the mode of conservation of algae. To identify limits of extraction, the structure and interactions of ulvan in the cell wall of Ulva were investigated

A. Robic; C. Rondeau-Mouro; J.-F. Sassi; Y. Lerat; M. Lahaye

2009-01-01

146

Overview on Biological Activities and Molecular Characteristics of Sulfated Polysaccharides from Marine Green Algae in Recent Years  

PubMed Central

Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits. PMID:25257786

Wang, Lingchong; Wang, Xiangyu; Wu, Hao; Liu, Rui

2014-01-01

147

Overview on biological activities and molecular characteristics of sulfated polysaccharides from marine green algae in recent years.  

PubMed

Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits. PMID:25257786

Wang, Lingchong; Wang, Xiangyu; Wu, Hao; Liu, Rui

2014-09-01

148

Bioaccumulation of Cr(III) ions by Blue Green alga Spirulina sp. Part I. A Comparison with Biosorption  

Microsoft Academic Search

The paper presents the results of studies on kinetics and equilibrium of bioaccumulati on process of Cr(III) ions by blue-green alga Spirulina sp. Bioaccumulation was described as the process that consists of two stages, passive (identical with biosorption) and active (accumulation inside the cells). The passive stage (similarly as biosorption itself) was found to be quick process and the subsequent

Katarzyna Chojnacka

149

Increase of Nitrogenase Activity in the Blue-Green Alga Nostoc muscorum (Cyanobacterium)  

PubMed Central

Preincubation of the blue-green alga (cyanobacterium) Nostoc muscorum under hydrogen or argon (nongrowing conditions, neither CO2 nor N2 or bound nitrogen present) in the light resulted in a two- to fourfold increase of light-induced hydrogen evolution and a 30% increase of acetylene reduction. Preincubation under the same gases in the dark led to a decrease of both activities. Cultivation of algae under a hydrogen-containing atmosphere (N2, H2, CO2) increased neither hydrogen nor ethylene evolution by the cells. Formation of both ethylene and hydrogen is due to nitrogenase activity, which apparently was induced by the absence of N2 or bound nitrogen and not by the presence of hydrogen. Inhibitors of protein biosynthesis prevented the increase of nitrogenase activity. Hydrogen uptake by the cells was almost unaffected under all of these conditions. With either ammonia or chloramphenicol present, nitrogenase activity decreased under growing conditions (i.e., an atmosphere of N2 and CO2). The kinetics of decrease were the same with ammonia or chloramphenicol, which was interpreted as being due to rapid protein breakdown with a half-life of approximately 4 h. The decay of nitrogenase activity caused by chloramphenicol could be counteracted by nitrogenase-inducing conditions, i.e., by the absence of N2 or bound nitrogen. A cell-free system from preconditioned algae with an adenosine 5?-triphosphate-generating system exhibited the same increase or decrease of nitrogenase activity as the intact cell filaments, indicating that this effect resided in the nitrogenase complex only. We tentatively assume that not the whole nitrogenase complex, but merely a subunit or a special protein with regulatory function, is susceptible to fast turnover. PMID:6777364

Scherer, Siegfried; Kerfin, Wolfgang; Böger, Peter

1980-01-01

150

Inhibition of target of rapamycin signaling by rapamycin in the unicellular green alga Chlamydomonas reinhardtii.  

PubMed

The macrolide rapamycin specifically binds the 12-kD FK506-binding protein (FKBP12), and this complex potently inhibits the target of rapamycin (TOR) kinase. The identification of TOR in Arabidopsis (Arabidopsis thaliana) revealed that TOR is conserved in photosynthetic eukaryotes. However, research on TOR signaling in plants has been hampered by the natural resistance of plants to rapamycin. Here, we report TOR inactivation by rapamycin treatment in a photosynthetic organism. We identified and characterized TOR and FKBP12 homologs in the unicellular green alga Chlamydomonas reinhardtii. Whereas growth of wild-type Chlamydomonas cells is sensitive to rapamycin, cells lacking FKBP12 are fully resistant to the drug, indicating that this protein mediates rapamycin action to inhibit cell growth. Unlike its plant homolog, Chlamydomonas FKBP12 exhibits high affinity to rapamycin in vivo, which was increased by mutation of conserved residues in the drug-binding pocket. Furthermore, pull-down assays demonstrated that TOR binds FKBP12 in the presence of rapamycin. Finally, rapamycin treatment resulted in a pronounced increase of vacuole size that resembled autophagic-like processes. Thus, our findings suggest that Chlamydomonas cell growth is positively controlled by a conserved TOR kinase and establish this unicellular alga as a useful model system for studying TOR signaling in photosynthetic eukaryotes. PMID:16299168

Crespo, José L; Díaz-Troya, Sandra; Florencio, Francisco J

2005-12-01

151

Genotoxic effects of commercial formulations of Chlorpyrifos and Tebuconazole on green algae.  

PubMed

The alkaline single-cell gel electrophoresis assay (comet assay) was used for the study of the genotoxic effects of insecticide Chlorpyrifos and fungicide Tebuconazole (commercial formulations) on two freshwater green algae species, Pseudokirchneriella subcapitata and Nannocloris oculata, after 24 h of exposure. The percentage of DNA in tail of migrating nucleoids was taken as an endpoint of DNA impairment. Cell viability was measured by fluorometric detection of chlorophyll "a" in vivo and the determination of cell auto-fluorescence. Only the higher concentration of Chlorpyrifos tested resulted to affect significantly the cell viability of P. subcapitata, whereas cells of N. oculata were not affected. Tebuconazole assayed concentrations (3 and 6 mg/l) did not affect cell viability of both species. The results of comet assay on P. subcapitata showed that Chlorpyrifos concentration evaluated (0.8 mg/l) exerted a genotoxic effects; while for the other specie a concentration of 10 mg/l was needed. Tebuconazole was genotoxic at 3 and 6 mg/l for both species. The comet assay evidenced damage at the level of DNA simple strains molecule at pesticide concentrations were cytotoxicity was not evident, demonstrating that algae are models to take into account in ecological risk assessments for aquatic environments. PMID:25230876

Martinez, Ricardo Santiago; Di Marzio, Walter Darío; Sáenz, María Elena

2015-01-01

152

Toxicity of polyfluorinated and perfluorinated compounds to lettuce (Lactuca sativa) and green algae (Pseudokirchneriella subcapitata).  

PubMed

Recently, polyfluorinated and perfluorinated compounds (PFCs) have been detected in most surface waters around the world. Because some PFCs are persistent and tend to accumulate in surface waters, their potential adverse effects to aquatic organisms have received increasing attention. Nevertheless, currently available toxicity information is limited. The aim of this study was to evaluate the toxicity effects of seven PFCs on root elongation of lettuce (Lactuca sativa) and photosynthesis of green algae (Pseudokirchneriella subcapitata). It was found that the toxicity profiles of both species tested were similar and had good relations with the fluorinated carbon-chain length of the PFCs investigated. One of the compounds tested, perfluorobutanoic acid, was found to be more toxic than expected in the algae test, which may be related with acidification of the test solution. It was concluded that because short-chained PFCs are becoming the predominant PFC pollutants in surface waters, their long-term toxicity and mixture toxicity with other PFCs should be studied in greater detail. PMID:21626016

Ding, Guanghui; Wouterse, Marja; Baerselman, Rob; Peijnenburg, Willie J G M

2012-01-01

153

Mössbauer study of cobalt and iron in the cyanobacterium (blue green alga)  

NASA Astrophysics Data System (ADS)

Mössbauer emission and absorption studies have been performed on cobalt and iron in the cyanobacterium (blue-green alga). The Mössbauer spectrum of the cyanobacterium cultivated with57Co is decomposed into two doublets. The parameters of the major doublet are in good agreement with those of cyanocobalamin (vitamin B12) labeled with57Co. The other minor doublet has parameters close to those of Fe(II) coordinated with six nitrogen atoms. These suggest that cobalt is used for the biosynthesis of vitamin B12 or its analogs in the cyanobacterium. The spectra of the cyanobacterium grown with57Fe show that iron is in the high-spin trivalent state and possibly in the form of ferritin, iron storage protein.

Ambe, Shizuko

1990-07-01

154

Fatty acid composition of unicellular strains of blue-green algae.  

PubMed

The fatty acids of 34 strains of unicellular blue-green algae provisionally assigned to the genera Synechococcus, Aphanocapsa, Gloeocapsa, Microcystis, and Chlorogloea by Stanier et al. have been chemically characterized. The strains analyzed can be divided into a series of compositional groups based upon the highest degree of unsaturation of the major cellular fatty acids. Twenty strains fall into the group characterized by one trienoic fatty acid isomer (alpha-linolenic acid), and seven strains fall into a group characterized by another trienoic acid isomer (gamma-linolenic acid). These groups in many cases correlate well with groupings based upon other phenotypic characters of the strains, e.g., deoxyribonucleic acid base composition. The assignment of a strain to a compositional group is not altered when the strain is grown under a variety of different culture conditions. All strains contain glycolipids with the properties of mono- and digalactosyldiglycerides. PMID:4621688

Kenyon, C N

1972-02-01

155

Vesicular trafficking in characean green algae and the possible involvement of a VAMP72-family protein  

PubMed Central

The RAB5 GTPase ARA6 of Arabidopsis thaliana is known to be involved in endosomal trafficking by targeting vesicles to the plasma membrane. During this process AtARA6 is working in close relationship with the SNARE protein VAMP727 (vesicle associated membrane protein 727). Recently, ARA6 of the characean green algae Chara australis (CaARA6) was shown to have properties similar to AtARA6, pointing to similar trafficking pathways. In order to gain further insight into the vesicle trafficking machinery of Characeae, C. australis was analyzed for homologous proteins of the VAMP72-family. A CaVAMP72 protein was detected and classified by protein sequence alignment and phylogenetic analyses. PMID:24614164

Hoepflinger, Marion C; Hametner, Christina; Ueda, Takashi; Foissner, Ilse

2014-01-01

156

Pectin metabolism and assembly in the cell wall of the charophyte green alga Penium margaritaceum.  

PubMed

The pectin polymer homogalacturonan (HG) is a major component of land plant cell walls and is especially abundant in the middle lamella. Current models suggest that HG is deposited into the wall as a highly methylesterified polymer, demethylesterified by pectin methylesterase enzymes and cross-linked by calcium ions to form a gel. However, this idea is based largely on indirect evidence and in vitro studies. We took advantage of the wall architecture of the unicellular alga Penium margaritaceum, which forms an elaborate calcium cross-linked HG-rich lattice on its cell surface, to test this model and other aspects of pectin dynamics. Studies of live cells and microscopic imaging of wall domains confirmed that the degree of methylesterification and sufficient levels of calcium are critical for lattice formation in vivo. Pectinase treatments of live cells and immunological studies suggested the presence of another class of pectin polymer, rhamnogalacturonan I, and indicated its colocalization and structural association with HG. Carbohydrate microarray analysis of the walls of P. margaritaceum, Physcomitrella patens, and Arabidopsis (Arabidopsis thaliana) further suggested the conservation of pectin organization and interpolymer associations in the walls of green plants. The individual constituent HG polymers also have a similar size and branched structure to those of embryophytes. The HG-rich lattice of P. margaritaceum, a member of the charophyte green algae, the immediate ancestors of land plants, was shown to be important for cell adhesion. Therefore, the calcium-HG gel at the cell surface may represent an early evolutionary innovation that paved the way for an adhesive middle lamella in multicellular land plants. PMID:24652345

Domozych, David S; Sřrensen, Iben; Popper, Zoë A; Ochs, Julie; Andreas, Amanda; Fangel, Jonatan U; Pielach, Anna; Sacks, Carly; Brechka, Hannah; Ruisi-Besares, Pia; Willats, William G T; Rose, Jocelyn K C

2014-05-01

157

Community interactions between the filamentous alga Cladophora glomerata (L.) Kuetzing, its epiphytes, and epiphyte grazers  

Microsoft Academic Search

Interactions between epiphytes, epiphyte grazers and the filamentous green alga Cladophora glomerata (L.) Kuetzing were explored with smaples from rivers in Montana. Extracts of C. glomerata lowered photosynthetic rates of Nitzschia fonticola Grunow (an epiphytic diatom). Nutrient enrichment showed that C. glomerata from the Madison River was N deficient and its epiphytes were P deficient on 2 dates and N

Walter K. Dodds

1991-01-01

158

Phylogenetic and morphological characterization of the green alga infesting the horse mussel Modiolus modiolus from Vityaz Bay (Peter the Great Bay, Sea of Japan).  

PubMed

In this work, the ultrastructural features and taxonomic position of the green microalga infesting the horse mussel Modiolus modiolus from the north-western Pacific (Vityaz Bay, Peter the Great Bay, Sea of Japan) are reported. Mussels were collected monthly from May to September of 2009. In different months, the prevalence of mussels with green tissues was 16.6-62.5% (mean 43%). The most affected organs were the mantle, digestive gland and gonad. Histological analysis revealed severe infiltration of the connective tissue by hemocytes containing the alga cells. Electron microscopy showed that the alga was morphologically similar to the green algae from the genus Coccomyxa (Chlorophyta: Chlorococcales). Two new primers were designed to generate partial small subunit (SSU) rRNA sequences of the green alga from M. modiolus. Phylogenetic analysis based on the comparison of the SSU rRNA sequences of the trebouxiophyceans confirmed an affiliation of the green alga with the genus Coccomyxa. The sequence (1296 bases) of the green alga from M. modiolus was most closely related to the sequence CPCC 508 (AM981206) (identity 100%), obtained from an acid-tolerant, free-living chlorophyte microalga Coccomyxa sp. and to the sequences EU127470 (identity 99.3%) and EU127471 (identity 99.7%) of the green alga, presumably the true Coccomyxa parasitica, infecting the blue mussel Mytilus edulis from the Flensburg Fjord (North Atlantic). PMID:22902969

Syasina, I G; Kukhlevsky, A D; Kovaleva, A L; Vaschenko, M A

2012-10-01

159

From algae to angiosperms–inferring the phylogeny of green plants (Viridiplantae) from 360 plastid genomes  

PubMed Central

Background Next-generation sequencing has provided a wealth of plastid genome sequence data from an increasingly diverse set of green plants (Viridiplantae). Although these data have helped resolve the phylogeny of numerous clades (e.g., green algae, angiosperms, and gymnosperms), their utility for inferring relationships across all green plants is uncertain. Viridiplantae originated 700-1500 million years ago and may comprise as many as 500,000 species. This clade represents a major source of photosynthetic carbon and contains an immense diversity of life forms, including some of the smallest and largest eukaryotes. Here we explore the limits and challenges of inferring a comprehensive green plant phylogeny from available complete or nearly complete plastid genome sequence data. Results We assembled protein-coding sequence data for 78 genes from 360 diverse green plant taxa with complete or nearly complete plastid genome sequences available from GenBank. Phylogenetic analyses of the plastid data recovered well-supported backbone relationships and strong support for relationships that were not observed in previous analyses of major subclades within Viridiplantae. However, there also is evidence of systematic error in some analyses. In several instances we obtained strongly supported but conflicting topologies from analyses of nucleotides versus amino acid characters, and the considerable variation in GC content among lineages and within single genomes affected the phylogenetic placement of several taxa. Conclusions Analyses of the plastid sequence data recovered a strongly supported framework of relationships for green plants. This framework includes: i) the placement of Zygnematophyceace as sister to land plants (Embryophyta), ii) a clade of extant gymnosperms (Acrogymnospermae) with cycads?+?Ginkgo sister to remaining extant gymnosperms and with gnetophytes (Gnetophyta) sister to non-Pinaceae conifers (Gnecup trees), and iii) within the monilophyte clade (Monilophyta), Equisetales?+?Psilotales are sister to Marattiales?+?leptosporangiate ferns. Our analyses also highlight the challenges of using plastid genome sequences in deep-level phylogenomic analyses, and we provide suggestions for future analyses that will likely incorporate plastid genome sequence data for thousands of species. We particularly emphasize the importance of exploring the effects of different partitioning and character coding strategies. PMID:24533922

2014-01-01

160

Enzymes Related to Lactate Metabolism in Green Algae and Lower Land Plants 1  

PubMed Central

Cell-free extracts of Chlorella pyrenoidosa contained two enzymes capable of oxidizing d-lactate; these were glycolate dehydrogenase and NAD+-dependent d-lactate dehydrogenase. The two enzymes could be distinguished by differential centrifugation, glycolate dehydrogenase being largely particulate and NAD+-d-lactate dehydrogenase being soluble. The reduction of pyruvate by NADH proceeded more rapidly than the reverse reaction, and the apparent Michaelis constants for pyruvate and NADH were lower than for d-lactate and NAD+. These data indicated that under physiological conditions, the NAD+-linked d-lactate dehydrogenase probably functions to produce d-lactate from pyruvate. Lactate dehydrogenase activity dependent on NAD+ was found in a number of other green algae and in the green tissues of a few lower land plants. When present in species which contain glycolate oxidase rather than glycolate dehydrogenase, the enzyme was specific for l-lactate rather than d-lactate. A cyclic system revolving around the production and utilization of d-lactate in some species and l-lactate in certain others is proposed. PMID:16658670

Gruber, Peter J.; Frederick, Sue Ellen; Tolbert, N. E.

1974-01-01

161

Natural synchronisation for the study of cell division in the green unicellular alga Ostreococcus tauri.  

PubMed

Ostreococcus tauri (Prasinophyceae) is a marine unicellular green alga which diverged early in the green lineage. The interest of O. tauri as a potential model to study plant cell division is based on its key phylogenetic position, its simple binary division, a very simple cellular organisation and now the availability of the full genome sequence. In addition O. tauri has a minimal yet complete set of cell cycle control genes. Here we show that division can be naturally synchronised by light/dark cycles and that organelles divide before the nucleus. This natural synchronisation, although being only partial, enables the study of the expression of CDKs throughout the cell cycle. The expression patterns of OtCDKA and OtCDKB were determined both at the mRNA and protein levels. The single OtCDKA gene is constantly expressed throughout the cell cycle, whereas OtCDKB is highly regulated and expressed only in S/G2/M phases. More surprisingly, OtCDKA is not phosphorylated at the tyrosine residue, in contrast to OtCDKB which is strongly phosphorylated during cell division. OtCDKA kinase activity appears before the S phase, indicating a possible role of this protein in the G1/S transition. OtCDKB kinase activity occurs later than OtCDKA, and its tyrosine phosphorylation is correlated to G2/M, suggesting a possible control of the mitotic activity. To our knowledge this is the first organism in the green lineage which showed CDKB tyrosine phosphorylation during cell cycle progression. PMID:16429264

Farinas, Benoît; Mary, Camille; de O Manes, Carmem-Lara; Bhaud, Yvonne; Peaucellier, Gérard; Moreau, Hervé

2006-01-01

162

Anaerobic and aerobic hydrogen gas formation by the blue-green alga Anabaena cylindrica.  

PubMed

An investigation was made of certain factors involved in the formation of hydrogen gas, both in an anaerobic environment (argon) and in air, by the blue-green alga Anabaena cylindrica. The alga had not been previously adapted under hydrogen gas and hence the hydrogen evolution occurred entirely within the nitrogen-fixing heterocyst cells; organisms grown in a fixed nitrogen source, and which were therefore devoid of heterocysts, did not produce hydrogen under these conditions. Use of the inhibitor dichlorophenyl-dimethyl urea showed that hydrogen formation was directly dependent on photosystem I and only indirectly dependent on photosystem II, consistent with heterocysts being the site of hydrogen formation. The uncouplers carbonyl cyanide chlorophenyl hydrazone and dinitrophenol almost completely inhibited hydrogen formation, indicating that the process occurs almost entirely via the adenosine 5'-triphosphate-dependent nitrogenase. Salicylaldoxime also inhibited hydrogen formation, again illustrating the necessity of photophosphorylation. Whereas hydrogen formation could usually only be observed in anaerobic, dinitrogen-free environments, incubation in the presence of the dinitrogen-fixing inhibitor carbon monoxide plus the hydrogenase inhibitor acetylene resulted in significant formation of hydrogen even in air. Hydrogen formation was studied in batch cultures as a function of age of the cultures and also as a function of culture concentration, in both cases the cultures being harvested in logarithmic growth. Hydrogen evolution (and acetylene-reducing activity) exhibited a distinct maximum with respect to the age of the cultures. Finally, the levels of the protective enzyme, superoxide dismutase, were measured in heterocyst and vegetative cell fractions of the organism; the level was twice as high in heterocyst cells (2.3 units/mg of protein) as in vegetative cells (1.1 units/mg of protein). A simple procedure for isolating heterocyst cells is described. PMID:412467

Daday, A; Platz, R A; Smith, G D

1977-11-01

163

Reconstruction of a human mitochondrial complex I mutation in the unicellular green alga Chlamydomonas.  

PubMed

Defects in complex I (NADH:ubiquinone oxidoreductase (EC 1.6.5.3)) are the most frequent cause of human respiratory disorders. The pathogenicity of a given human mitochondrial mutation can be difficult to demonstrate because the mitochondrial genome harbors large numbers of polymorphic base changes that have no pathogenic significance. In addition, mitochondrial mutations are usually found in the heteroplasmic state, which may hide the biochemical effect of the mutation. We propose that the unicellular green alga Chlamydomonas could be used to study such mutations because (i) respiratory complex-deficient mutants are viable and mitochondrial mutations are found in the homoplasmic state, (ii) transformation of the mitochondrial genome is feasible, and (iii) Chlamydomonas complex I is similar to that of humans. To illustrate this proposal, we introduced a Leu157Pro substitution into the Chlamydomonas ND4 subunit of complex I in two recipient strains by biolistic transformation, demonstrating that site-directed mutagenesis of the Chlamydomonas mitochondrial genome is possible. This substitution did not lead to any respiratory enzyme defects when present in the heteroplasmic state in a patient with chronic progressive external ophthalmoplegia. When present in the homoplasmic state in the alga, the mutation does not prevent assembly of whole complex I (950 kDa) and the NADH dehydrogenase activity of the peripheral arm of the complex is mildly affected. However, the NADH:duroquinone oxidoreductase activity is strongly reduced, suggesting that the substitution could affect binding of ubiquinone to the membrane domain. The in vitro defects correlate with a decrease in dark respiration and growth rate in vivo. PMID:22268373

Larosa, Véronique; Coosemans, Nadine; Motte, Patrick; Bonnefoy, Nathalie; Remacle, Claire

2012-06-01

164

Evaluation of toxicity data to green algae and relationship with hydrophobicity.  

PubMed

The quality of the biological activity data is of great importance for the development of algal quantitative structure-activity relationship (QSAR) models. However, a number of algal QSAR models in the literature were developed based on toxicity data without considering the response endpoints, exposure periods and species sensitivity. In this paper, 2323 algal toxicity data (log 1/EC50) in different toxicity response endpoints for 1081 compounds to 26 algal species within different exposure periods (14 and 15 min; 24, 48, 72, 96, 168 and 192 h) were used to evaluate the quality of the toxicity data to green algae. Analysis of 72 h toxicity to algae showed that the closed test had the same sensitivity as the open test for most of the test compounds, but a significant difference was observed for a few compounds. The overall average difference for all compounds ranges from 0.15 to 0.43 log units between toxicity endpoints (yield–growth rate). The relationships between exposure periods of 24, 48, 72 and 96 h indicated that 48 h exposure period is the most sensitive for algal growth inhibition test, and its sensitivity is 0.25 log units greater than 72 and 96 h exposure periods, respectively. Interspecies relationships showed that some algal species have very close sensitivity (e.g. Pseudokirchneriella subcapitata and Chlorella pyrenoidosa or Chlorella vulgaris and Scenedesmus obliquus, respectively), whereas some species have significantly different sensitivity (e.g. P. subcapitata and S. obliquus). Relationships between toxicity and hydrophobicity demonstrated that no difference was observed for non-polar narcotics within different exposure periods (24, 48, 72, and 96 h) or response variables (yield and growth rate). For polar narcotics, in contrast, algal toxicity is dependent on algal species and is related to the response variables and exposure period. We cannot expect significant QSAR models between algal toxicity and descriptors without considering species sensitivity, exposure periods and response endpoints. PMID:25462296

Fu, Ling; Li, Jin J; Wang, Yu; Wang, Xiao H; Wen, Yang; Qun, Wei C; Su, Li M; Zhao, Yuan H

2015-02-01

165

Insights into intrathalline genetic diversity of the cosmopolitan lichen symbiotic green alga Trebouxia decolorans Ahmadjian using microsatellite markers.  

PubMed

Trebouxia decolorans is a widespread and common symbiotic green alga that is found in association with different species of lichen-forming fungi. By applying T. decolorans-specific microsatellite markers, we investigated the within-thallus diversity of T. decolorans in thalli of Xanthoria parietina and Anaptychia ciliaris. We found several algal strains in most of the thalli of both hosts. High genetic differentiation among thalli suggests that algal diversity is generated de novo via mutation in both fungal hosts. Rarefied allelic richness of the algae was higher in thalli of X. parietina. Our results indicate that in X. parietina intrathalline algal diversity is additionally created by environmental uptake of algae either at the start of the symbiotic association or during the lifetime of the thallus. This study indicates that promiscuous host-symbiont associations in lichen symbioses with Trebouxia spp. may be more common than currently recognized. PMID:24412431

Dal Grande, Francesco; Alors, David; Divakar, Pradeep K; Bálint, Miklós; Crespo, Ana; Schmitt, Imke

2014-03-01

166

Effect of scenedesmus acuminatus green algae extracts on the development of Candida lipolytic yeast in gas condensate-containing media  

NASA Technical Reports Server (NTRS)

Data are given of a comparative study of the growth and development as well as the characteristics of the biomass of the C. Lipolytica yeast according to the content of raw protein, protein, lipids, vitamins in the B group, and residual hydrocarbons during growth in media with de-aromatized gas-condensate FNZ as the carbon source with aqueous and alcohol extracts of S. acuminatus as the biostimulants. It is shown that the decoction and aqueous extract of green algae has the most intensive stimulating effect on the yeast growth. When a decoction of algae is added to the medium, the content of residual hydrocarbons in the biomass of C. lipolytica yeast is reduced by 4%; the quantity of protein, lipids, thamine and inositol with replacement of the yeast autolysate by the decoction of algae is altered little.

Bilmes, B. I.; Kasymova, G. A.; Runov, V. I.; Karavayeva, N. N.

1980-01-01

167

Diatom Communities and Metrics as Indicators of Urbanization Effects on Streams and Potential Moderation by Landscape Green Infrastructure  

EPA Science Inventory

Diatoms are very useful and important indicators of anthropogenic impacts on streams because they are the foundation of primary production and are responsive to nutrients, conductivity, and habitat conditions. We characterized relationships of diatom assemblages with water chemis...

168

[Peculiarities of growth of the monocellular green algae culture after the influence of electromagnetic field in deuterated water-containing media].  

PubMed

Exposing the inoculum of monocellular green algae Dunalialla tertiolecta and Tetraselmis viridis to 50 Hz electromagnetic field for several hours resulted in a reduced growth rate in both cultures. It was ascertained that heavy water inhibited growth of algae Dunaliella tertiolecta. The light water activated growth of the culture in the exponential phase only. PMID:23650857

Semenov, K T; Aslanian, R R

2013-01-01

169

Response of the green alga Oophila sp., a salamander endosymbiont, to a PSII-inhibitor under laboratory conditions.  

PubMed

In a rare example of autotroph-vertebrate endosymbiosis, eggs of the yellow-spotted salamander (Ambystoma maculatum) are colonized by a green alga (Oophila sp.) that significantly enhances salamander development. Previous studies have demonstrated the potential for impacts to the salamander embryo when growth of the algae is impaired by exposure to herbicides. To further investigate this relationship, the authors characterized the response of the symbiotic algae (Oophila sp.) alone to the photosystem II (PSII) inhibitor atrazine under controlled laboratory conditions. After extraction of the alga from A. maculatum eggs and optimization of culturing conditions, 4 toxicity assays (96 h each) were conducted. Recovery of the algal population was also assessed after a further 96 h in untreated media. Average median effective concentration (EC50) values of 123 µg L(-1) (PSII yield), 169 µg L(-1) (optical density), and 299 µg L(-1) (growth rate) were obtained after the 96-h exposure. Full recovery of exposed algal populations after 96 h in untreated media was observed for all endpoints, except for optical density at the greatest concentration tested (300 µg L(-1) ). Our results show that, under laboratory conditions, Oophila sp. is generally less sensitive to atrazine than standard test species. Although conditions of growth in standard toxicity tests are not identical to those in the natural environment, these results provide an understanding of the tolerance of this alga to PSII inhibitors as compared with other species. PMID:24782078

Baxter, Leilan; Brain, Richard; Rodriguez-Gil, Jose Luis; Hosmer, Alan; Solomon, Keith; Hanson, Mark

2014-08-01

170

Culture observation and molecular phylogenetic analysis on the blooming green alga Chaetomorpha valida (Cladophorales, Chlorophyta) from China  

NASA Astrophysics Data System (ADS)

The marine green alga Chaetomorpha valida fouls aquaculture ponds along the coastal cities of Dalian and Rongcheng, China. Unialgal cultures were observed under a microscope to determine the developmental morphological characters of C. valida. Results reveal that gametophytic filaments often produce lateral branches under laboratory culture conditions, suggesting an atypical heteromorphic life cycle of C. valida between unbranched sporophytes and branched gametophytes, which differs from typical isomorphic alternation of Chaetomorpha species. The shape of the basal attachment cell, an important taxonomic character within the genus, was found variable depending on environmental conditions. The 18S rDNA and 28S rDNA regions were used to explore the phylogenetic affinity of the taxa. Inferred trees from 18S rDNA sequences revealed a close relationship between C. valida and Chaetomorpha moniligera. These results would enrich information in general biology and morphological plasticity of C. valida and provided a basis for future identification of green tide forming algae.

Deng, Yunyan; Tang, Xiaorong; Zhan, Zifeng; Teng, Linhong; Ding, Lanping; Huang, Bingxin

2013-05-01

171

Complex phylogenetic distribution of a non-canonical genetic code in green algae  

PubMed Central

Background A non-canonical nuclear genetic code, in which TAG and TAA have been reassigned from stop codons to glutamine, has evolved independently in several eukaryotic lineages, including the ulvophycean green algal orders Dasycladales and Cladophorales. To study the phylogenetic distribution of the standard and non-canonical genetic codes, we generated sequence data of a representative set of ulvophycean green algae and used a robust green algal phylogeny to evaluate different evolutionary scenarios that may account for the origin of the non-canonical code. Results This study demonstrates that the Dasycladales and Cladophorales share this alternative genetic code with the related order Trentepohliales and the genus Blastophysa, but not with the Bryopsidales, which is sister to the Dasycladales. This complex phylogenetic distribution whereby all but one representative of a single natural lineage possesses an identical deviant genetic code is unique. Conclusions We compare different evolutionary scenarios for the complex phylogenetic distribution of this non-canonical genetic code. A single transition to the non-canonical code followed by a reversal to the canonical code in the Bryopsidales is highly improbable due to the profound genetic changes that coincide with codon reassignment. Multiple independent gains of the non-canonical code, as hypothesized for ciliates, are also unlikely because the same deviant code has evolved in all lineages. Instead we favor a stepwise acquisition model, congruent with the ambiguous intermediate model, whereby the non-canonical code observed in these green algal orders has a single origin. We suggest that the final steps from an ambiguous intermediate situation to a non-canonical code have been completed in the Trentepohliales, Dasycladales, Cladophorales and Blastophysa but not in the Bryopsidales. We hypothesize that in the latter lineage an initial stage characterized by translational ambiguity was not followed by final reassignment of both stop codons to glutamine. Instead the standard code was retained by the disappearance of the ambiguously decoding tRNAs from the genome. We correlate the emergence of a non-canonical genetic code in the Ulvophyceae to their multinucleate nature. PMID:20977766

2010-01-01

172

Carotenoids in the eyespot apparatus of the flagellate green alga Spermatozopsis similis : Adaptation to the retinal-based photoreceptor  

Microsoft Academic Search

Isolated intact eyespot apparatuses, the photoreceptive organelles involved in blue-light-mediated photoresponses of flagellate green algae, were analyzed regarding their carotenoid composition. Carotenoids from the eyespot apparatuses of Spermatozopsis similis were identified by high-performance liquid chromatography, visible-light absorption spectra, mass spectroscopy and by 1H-nuclear magnetic resonance spectroscopy (carotenes), and compared with those of whole-cell extracts. Both extracts contained ß,ß-carotene, ß,?-carotene (formerly

Merete Grung; Georg Kreimer; Michael Calenberg; Michael Melkonian; Synnřve Liaaen-Jensen

1994-01-01

173

Shear-oriented Microfibrils in the Mucilaginous Investments of Two Motile Oscillatoriacean Blue-Green Algae1  

PubMed Central

Trichomes of two oscillatoriacean blue-green algae execute screw-like gliding motion, but the two organisms differ from each other with respect to the screw sense of motion. Electron microscopy of serial longitudinal sections reveals extracellular microfibrils which lie roughly parallel to stream-lines at the surface of each organism. The author proposes that the microfibrils are oriented by shear in a zone just external to the outer unit membrane-like component of the cell wall. Images PMID:5764337

Lamont, Hayes C.

1969-01-01

174

Nitrogen-fixation associated with the marine blue-green alga, Trichodesmium , as measured by the acetylene-reduction technique  

Microsoft Academic Search

The marine blue-green alga, Trichodesmium, was collected from the Gulf Stream, near Miami, and occurred in two distinct colonial forms both of which reduced acetylene to ethylene. Trichodesmium was more abundant during the summer but its acetylene-reducing potential showed no obvious seasonal variation. Illuminated Trichodesmium reduced acetylene to ethylene equally well either anaerobically or aerobically (20% oxygen). Acetylene-reduction in the

Barrie F. Taylor; Chun C. Lee; John S. Bunt

1973-01-01

175

Vanillic acid derivatives from the green algae Cladophora socialis as potent protein tyrosine phosphatase 1B inhibitors.  

PubMed

A novel vanillic acid derivative (1) and its sulfate adduct (2) were isolated from a green algae, Cladophora socialis. The structures of 1 and 2 were elucidated from NMR and HRESIMS experiments. Both compounds showed potent inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), an enzyme involved in the regulation of insulin cell signaling. Compounds 1 and 2 had IC50 values of 3.7 and 1.7 microM, respectively. PMID:17949055

Feng, Yunjiang; Carroll, Anthony R; Addepalli, Rama; Fechner, Gregory A; Avery, Vicky M; Quinn, Ronald J

2007-11-01

176

Strategies for psbA gene expression in cyanobacteria, green algae and higher plants: from transcription to PSII repair.  

PubMed

The Photosystem (PS) II of cyanobacteria, green algae and higher plants is prone to light-induced inactivation, the D1 protein being the primary target of such damage. As a consequence, the D1 protein, encoded by the psbA gene, is degraded and re-synthesized in a multistep process called PSII repair cycle. In cyanobacteria, a small gene family codes for the various, functionally distinct D1 isoforms. In these organisms, the regulation of the psbA gene expression occurs mainly at the level of transcription, but the expression is fine-tuned by regulation of translation elongation. In plants and green algae, the D1 protein is encoded by a single psbA gene located in the chloroplast genome. In chloroplasts of Chlamydomonas reinhardtii the psbA gene expression is strongly regulated by mRNA processing, and particularly at the level of translation initiation. In chloroplasts of higher plants, translation elongation is the prevalent mechanism for regulation of the psbA gene expression. The pre-existing pool of psbA transcripts forms translation initiation complexes in plant chloroplasts even in darkness, while the D1 synthesis can be completed only in the light. Replacement of damaged D1 protein requires also the assistance by a number of auxiliary proteins, which are encoded by the nuclear genome in green algae and higher plants. Nevertheless, many of these chaperones are conserved between prokaryotes and eukaryotes. Here, we describe the specific features and fundamental differences of the psbA gene expression and the regeneration of the PSII reaction center protein D1 in cyanobacteria, green algae and higher plants. This article is part of a Special Issue entitled Photosystem II. PMID:21565160

Mulo, Paula; Sakurai, Isamu; Aro, Eva-Mari

2012-01-01

177

Bioaccumulation of Cr(III) ions by Blue Green-alga Spirulina sp. Part II. Mathematical Modeling  

Microsoft Academic Search

In the present paper bioaccumulation of Cr(III) ions by blue -green algae Spirulina sp. is discussed. We found that the process consisted of two stages: passive in which Cr(III) ions are bound to the surface of cells, identical with biosorption and active, metabolism-dependent, in which Cr(III) ions are transported into the cellular interior. The passive stage occurs in both living

Katarzyna Chojnacka; Piotr M. Wojciechowski

178

Effect of urea, blue green algae and Azolla on nitrogen fixation and chlorophyll accumulation in soil under rice  

Microsoft Academic Search

Nitrogen fixing potential in terms of acetylene reducing activity (ARA) and biomass accumulation (in terms of chlorophyll) were investigated using surface and below-surface soil cores, collected from rice fields 45 and 90 days after transplanting (DAT). Treatments included different levels of urea (30, 60, 90 and 120 kg N ha -1) in combination with inoculation using blue green algae (BGA) and Azolla biofertilizers. Application

Saswati Nayak; Radha Prasanna; Anjuli Pabby; T. K. Dominic; P. K. Singh

2004-01-01

179

Effects of different levels of chemical Nitrogen (urea) on Azolla and Blue-green algae intercropping with rice  

Microsoft Academic Search

Application of higher levels (60 and 90 kg N ha-1) of nitrogen fertilizer (Urea) inhibited the growth ofAzolla pinnata (Bangkok) and blue-green algae (BGA) though the reduction was more in BGA thanAzolla. Inoculation of 500 kg ha-1 of freshAzolla 10 days after transplanting (DAT) in the rice fields receiving 30, 60 and 90 kg N ha-1 as urea produced an

A. L. Singh; P. K. Singh; Pushp Lata

1988-01-01

180

Molecular Identification of Rickettsial Endosymbionts in the Non-Phagotrophic Volvocalean Green Algae  

PubMed Central

Background The order Rickettsiales comprises Gram-negative obligate intracellular bacteria (also called rickettsias) that are mainly associated with arthropod hosts. This group is medically important because it contains human-pathogenic species that cause dangerous diseases. Until now, there has been no report of non-phagotrophic photosynthetic eukaryotes, such as green plants, harboring rickettsias. Methodology/Principal Findings We examined the bacterial endosymbionts of two freshwater volvocalean green algae: unicellular Carteria cerasiformis and colonial Pleodorina japonica. Epifluorescence microscopy using 4?-6-deamidino-2-phenylindole staining revealed the presence of endosymbionts in all C. cerasiformis NIES-425 cells, and demonstrated a positive correlation between host cell size and the number of endosymbionts. Strains both containing and lacking endosymbionts of C. cerasiformis (NIES-425 and NIES-424) showed a >10-fold increase in cell number and typical sigmoid growth curves over 192 h. A phylogenetic analysis of 16 S ribosomal (r)RNA gene sequences from the endosymbionts of C. cerasiformis and P. japonica demonstrated that they formed a robust clade (hydra group) with endosymbionts of various non-arthropod hosts within the family Rickettsiaceae. There were significantly fewer differences in the 16 S rRNA sequences of the rickettsiacean endosymbionts between C. cerasiformis and P. japonica than in the chloroplast 16 S rRNA or 18 S rRNA of the host volvocalean cells. Fluorescence in situ hybridization demonstrated the existence of the rickettsiacean endosymbionts in the cytoplasm of two volvocalean species. Conclusions/Significance The rickettsiacean endosymbionts are likely not harmful to their volvocalean hosts and may have been recently transmitted from other non-arthropod organisms. Because rickettsias are the closest relatives of mitochondria, incipient stages of mitochondrial endosymbiosis may be deduced using both strains with and without C. cerasiformis endosymbionts. PMID:22363720

Kawafune, Kaoru; Hongoh, Yuichi; Hamaji, Takashi; Nozaki, Hisayoshi

2012-01-01

181

Isolation of a novel oil globule protein from the green alga Haematococcus pluvialis (Chlorophyceae).  

PubMed

Cytoplasmic oil globules of Haematococcus pluvialis (Chlorophyceae) were isolated and analyzed for pigments, lipids and proteins. Astaxanthin appeared to be the only pigment deposited in the globules. Triacyglycerols were the main lipids (more than 90% of total fatty acids) in both the cell-free extract and in the oil globules. Lipid profile analysis of the oil globules showed that relative to the cell-free extract, they were enriched with extraplastidial lipids. A fatty acids profile revealed that the major fatty acids in the isolated globules were oleic acid (18:1) and linoleic acid (18:2). Protein extracts from the globules revealed seven enriched protein bands, all of which were possible globule-associated proteins. A major 33-kDa globule protein was partially sequenced by MS/MS analysis, and degenerate DNA primers were prepared and utilized to clone its encoding gene from cDNA extracted from cells grown in a nitrogen depleted medium under high light. The sequence of this 275-amino acid protein, termed the Haematococcus Oil Globule Protein (HOGP), revealed partial homology with a Chlamydomonas reinhardtii oil globule protein and with undefined proteins from other green algae. The HOGP transcript was barely detectable in vegetative cells, but its level increased by more than 100 fold within 12 h of exposure to nitrogen depletion/high light conditions, which induced oil accumulation. HOGP is the first oil-globule-associated protein to be identified in H. pluvialis, and it is a member of a novel gene family that may be unique to green microalgae. PMID:21732215

Peled, Ehud; Leu, Stefan; Zarka, Aliza; Weiss, Meira; Pick, Uri; Khozin-Goldberg, Inna; Boussiba, Sammy

2011-09-01

182

High Yields of Hydrogen Production Induced by Meta-Substituted Dichlorophenols Biodegradation from the Green Alga Scenedesmus obliquus  

PubMed Central

Hydrogen is a highly promising energy source with important social and economic implications. The ability of green algae to produce photosynthetic hydrogen under anaerobic conditions has been known for years. However, until today the yield of production has been very low, limiting an industrial scale use. In the present paper, 73 years after the first report on H2-production from green algae, we present a combinational biological system where the biodegradation procedure of one meta-substituted dichlorophenol (m-dcp) is the key element for maintaining continuous and high rate H2-production (>100 times higher than previously reported) in chloroplasts and mitochondria of the green alga Scenedesmus obliquus. In particular, we report that reduced m-dcps (biodegradation intermediates) mimic endogenous electron and proton carriers in chloroplasts and mitochondria, inhibit Photosystem II (PSII) activity (and therefore O2 production) and enhance Photosystem I (PSI) and hydrogenase activity. In addition, we show that there are some indications for hydrogen production from sources other than chloroplasts in Scenedesmus obliquus. The regulation of these multistage and highly evolved redox pathways leads to high yields of hydrogen production and paves the way for an efficient application to industrial scale use, utilizing simple energy sources and one meta-substituted dichlorophenol as regulating elements. PMID:23145057

Papazi, Aikaterini; Andronis, Efthimios; Ioannidis, Nikolaos E.; Chaniotakis, Nikolaos; Kotzabasis, Kiriakos

2012-01-01

183

Phytochrome of the green alga Mougeotia: cDNA sequence, autoregulation and phylogenetic position.  

PubMed

A cDNA clone encoding phytochrome (apoprotein) of the zygnematophycean green alga Mougeotia scalaris has been isolated and sequenced. The clone consisted of 3372 bp, encoded 1124 amino acids, and showed strainspecific nucleotide exchanges for M. scalaris, originating from different habitats. No indication was found of multiple phytochrome genes in Mougeotia. The 5' non-coding region of the Mougeotia PHY cDNA harbours a striking stem-loop structure. Homologies with higher-plant phytochromes were 52-53% for PHYA and 57-59% for PHYB. Highest homology scores were found with lower-plant phytochromes, for example 67% for Selaginella (Lycopodiopsida), 64% for Physcomitrella (Bryopsida) and 73% for Mesotaenium (Zygnematophyceae). In an unrooted phylogenetic tree, the position of Mougeotia PHY appeared most distant to all other known PHYs. The amino acids Gly-Val in the chromophore-binding domain (-Arg-Gly-Val-His-Gly-Cys-) were characteristic of the zygnematophycean PHYs known to date. There was no indication of a transmembrane region in Mougeotia phytochrome in particular, but a carboxyl-terminal 16-mer three-fold repeat in both, Mougeotia and Mesotaenium PHYs may represent a microtubule-binding domain. Unexpected for a non-angiosperm phytochrome, its expression was autoregulated in Mougeotia in a red/far-red reversible manner: under Pr conditions, phytochrome mRNA levels were tenfold higher than under Pfr conditions. PMID:8980511

Winands, A; Wagner, G

1996-11-01

184

?-Tocopherol methyltransferase from the green alga Chlamydomonas reinhardtii: functional characterization and expression analysis.  

PubMed

?-Tocopherol methyltransferase (?-TMT) (EC 2.1.1.95) is a very important enzyme in tocopherol biosynthesis in all photosynthetic organisms. In this paper, we present the functional characterization and expression analysis of ?-TMT from the unicellular green alga Chlamydomonas reinhardtii. Recombinant TMT1 enzyme was purified and characterized. The size of TMT1 subunit was estimated as 37 kDa by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), in accordance with the predicted molecular size after TMT1 cDNA sequence. Recombinant TMT1 also showed an apparent molecular mass of 37 kDa in its native conformation, suggesting that native TMT1 has a monomeric structure similar to the plant TMTs already characterized. pH and temperature dependence of TMT1 activity were also similar to plant TMTs. Substrate specificity studies showed that Chlamydomonas TMT1 is responsible for the conversion of ?- and ?-tocopherol to ?- and ?-tocopherol, respectively. The kinetic properties of Chlamydomonas recombinant ?-TMT activity were studied and ?-TMT1 has a similar affinity for ?- and ?-tocopherol. Promoter sequence analysis and expression analysis by northern blot revealed that tmt1 expression is strongly upregulated by high light and downregulated by low temperature. This regulatory pattern of tmt1 expression supports the idea that ?- and ?-tocopherol play specific roles in the adaptation to growth under low temperature and high light stress conditions. PMID:21883249

Gálvez-Valdivieso, Gregorio; Cardeńosa, Rosa; Vera, José Manuel; Pineda, Manuel; Aguilar, Miguel

2011-12-01

185

Prasinoviruses of the Marine Green Alga Ostreococcus tauri Are Mainly Species Specific  

PubMed Central

Prasinoviruses infecting unicellular green algae in the order Mamiellales (class Mamiellophyceae) are commonly found in coastal marine waters where their host species frequently abound. We tested 40 Ostreococcus tauri viruses on 13 independently isolated wild-type O. tauri strains, 4 wild-type O. lucimarinus strains, 1 Ostreococcus sp. (“Ostreococcus mediterraneus”) clade D strain, and 1 representative species of each of two other related species of Mamiellales, Bathycoccus prasinos and Micromonas pusilla. Thirty-four out of 40 viruses infected only O. tauri, 5 could infect one other species of the Ostreococcus genus, and 1 infected two other Ostreococcus spp., but none of them infected the other genera. We observed that the overall susceptibility pattern of Ostreococcus strains to viruses was related to the size of two host chromosomes known to show intraspecific size variations, that genetically related viruses tended to infect the same host strains, and that viruses carrying inteins were strictly strain specific. Comparison of two complete O. tauri virus proteomes revealed at least three predicted proteins to be candidate viral specificity determinants. PMID:22318150

Clerissi, Camille; Desdevises, Yves

2012-01-01

186

Isolation of Prasinoviruses of the Green Unicellular Algae Ostreococcus spp. on a Worldwide Geographical Scale? †  

PubMed Central

Ostreococcus spp. are extremely small unicellular eukaryotic green algae found worldwide in marine environments, and they are susceptible to attacks by a diverse group of large DNA viruses. Several biologically distinct species of Ostreococcus are known and differ in the ecological niches that they occupy: while O. tauri (representing clade C strains) is found in marine lagoons and coastal seas, strains belonging to clade A, exemplified by O. lucimarinus, are present in different oceans. We used laboratory cultures of clonal isolates of these two species to assay for the presence of viruses in seawater samples from diverse locations. In keeping with the distributions of their host strains, we found a decline in the abundance of O. tauri viruses from a lagoon in southwest France relative to the Mediterranean Sea, whereas in the ocean, no O. tauri viruses were detected. In contrast, viruses infecting O. lucimarinus were detected from distantly separated oceans. DNA sequencing, phylogenetic analyses using a conserved viral marker gene, and a Mantel test revealed no relationship between geographic and phylogenetic distances in viruses infecting O. lucimarinus. PMID:19897754

Bellec, Laure; Grimsley, Nigel; Desdevises, Yves

2010-01-01

187

Effects of lead on tolerance, bioaccumulation, and antioxidative defense system of green algae, Cladophora.  

PubMed

Effects of various concentrations (0.5, 1.0, 2.5, 5.0, 7.5, and 10.0mg/L) of lead (Pb(2+)) on the growth, bioaccumulation, and antioxidative defense system of green algae, Cladophora, was investigated. Low concentrations of Pb(2+) accelerated Cladophora growth, but concentrations of 10.0mg/L and above inhibited the growth because of the hinderance to photosynthesis. The total soluble sugar content of Cladophora was affected by Pb(2+) treatment, but the protein content showed no significant changes. The malondialdehyde (MDA) content and peroxidase(POD) activity of Cladophora gradually increased whereas superoxide dismutase(SOD) decreased with Pb(2+) concentrations. Catalase (CAT) activity exhibited no significant changes following Pb(2+) treatment. Pb(2+) accumulated in Cladophora and that the lead content in Cladophora was correlated with POD growth, MDA, and Metallothionein (MT). POD and MT play a role in the survival of Cladophora in Pb-contaminated environments. This study suggests that Cladophora can be a choice organism for the phytoremediation of Pb-polluted coastal areas. PMID:25463875

Cao, De-Ju; Shi, Xiao-Dong; Li, Hao; Xie, Pan-Pan; Zhang, Hui-Min; Deng, Juan-Wei; Liang, Yue-Gan

2015-02-01

188

Growth rate affects the responses of the green alga Tetraselmis suecica to external perturbations.  

PubMed

Acclimation to environmental changes involves a modification of the expressed proteome and metabolome. The reproductive advantage associated with the higher fitness that acclimation provides to the new conditions more than compensates for the costs of acclimation. To exploit such an advantage, however, the duration of the perturbation must be sufficiently long relative to the growth rate. Otherwise, a selective pressure may exist in favour of responses that minimize changes in carbon allocation and resource use and do not require reversal of the acclimation after the perturbation ceases (compositional homeostasis). We hypothesize that the choice between acclimation and homeostasis depends on the duration of the perturbation relative to the length of the cell cycle. To test this hypothesis, we cultured the green alga Tetraselmis suecica at two growth rates and subjected the cultures to three environmental perturbations. Carbon allocation was studied with Fourier transform infrared (FTIR) spectroscopy; elemental stoichiometry was investigated by total reflection X-ray fluorescence (TXRF) spectroscopy. Our data confirmed that growth rate is a crucial factor for C allocation in response to external changes, with a higher degree of compositional homeostasis in cells with lower growth rate. PMID:23927015

Fanesi, Andrea; Raven, John A; Giordano, Mario

2014-02-01

189

Tracking the invasive history of the green alga Codium fragile ssp. tomentosoides.  

PubMed

The spread of nonindigenous species into new habitats is having a drastic effect on natural ecosystems and represents an increasing threat to global biodiversity. In the marine environment, where data on the movement of invasive species is scarce, the spread of alien seaweeds represents a particular problem. We have employed a combination of plastid microsatellite markers and DNA sequence data from three regions of the plastid genome to trace the invasive history of the green alga Codium fragile ssp. tomentosoides. Extremely low levels of genetic variation were detected, with only four haplotypes present in the species' native range in Japan and only two of these found in introduced populations. These invasive populations displayed a high level of geographical structuring of haplotypes, with one haplotype localized in the Mediterranean and the other found in Northwest Atlantic, northern European and South Pacific populations. Consequently, we postulate that there have been at least two separate introductions of C. fragile ssp. tomentosoides from its native range in the North Pacific. PMID:15643962

Provan, Jim; Murphy, Susan; Maggs, Christine A

2005-01-01

190

Removal of malachite green by using an invasive marine alga Caulerpa racemosa var. cylindracea.  

PubMed

The biosorption of a cationic dye, malachite green oxalate (MG) from aqueous solution onto an invasive marine alga Caulerpa racemosa var. cylindracea (CRC) was investigated at different temperatures (298, 308 and 318 K). The dye adsorption onto CRC was confirmed by FTIR analysis. Equilibrium data were analyzed using Freundlich, Langmuir and Dubinin-Radushkevich (DR) equations. All of the isotherm parameters were calculated. The Freundlich model gave a better conformity than Langmuir equation. The mean free energy values (E) from DR isotherm were also estimated. In order to clarify the sorption kinetic, the fit of pseudo-first-order kinetic model, second-order kinetic model and intraparticle diffusion model were investigated. It was obtained that the biosorption process followed the pseudo-second-order rate kinetics. From thermodynamic studies the free energy changes were found to be -7.078, -9.848 and -10.864 kJ mol(-1) for 298, 308 and 318 K, respectively. This implied the spontaneous nature of biosorption and the type of adsorption as physisorption. Activation energy value for MG sorption (E(a)) was found to be 37.14 kJ mol(-1). It could be also derived that this result supported physisorption as a type of adsorption. PMID:18562093

Bekçi, Zehra; Seki, Yolda?; Cavas, Levent

2009-01-30

191

Comparison of ESTs from juvenile and adult phases of the giant unicellular green alga Acetabularia acetabulum  

PubMed Central

Background Acetabularia acetabulum is a giant unicellular green alga whose size and complex life cycle make it an attractive model for understanding morphogenesis and subcellular compartmentalization. The life cycle of this marine unicell is composed of several developmental phases. Juvenile and adult phases are temporally sequential but physiologically and morphologically distinct. To identify genes specific to juvenile and adult phases, we created two subtracted cDNA libraries, one adult-specific and one juvenile-specific, and analyzed 941 randomly chosen ESTs from them. Results Clustering analysis suggests virtually no overlap between the two libraries. Preliminary expression data also suggests that we were successful at isolating transcripts differentially expressed between the two developmental phases and that many transcripts are specific to one phase or the other. Comparison of our EST sequences against publicly available sequence databases indicates that ESTs from the adult and the juvenile libraries partition into different functional classes. Three conserved sequence elements were common to several of the ESTs and were also found within the genomic sequence of the carbonic anhydrase1 gene from A. acetabulum. To date, these conserved elements are specific to A. acetabulum. Conclusions Our data provide strong evidence that adult and juvenile phases in A. acetabulum vary significantly in gene expression. We discuss their possible roles in cell growth and morphogenesis as well as in phase change. We also discuss the potential role of the conserved elements found within the EST sequences in post-transcriptional regulation, particularly mRNA localization and/or stability. PMID:15070428

Henry, Isabelle M; Wilkinson, Mark D; Hernandez, J Marcela; Schwarz-Sommer, Zsuzsanna; Grotewold, Erich; Mandoli, Dina F

2004-01-01

192

Dopamine functions as an antiherbivore defense in the temperate green alga Ulvaria obscura.  

PubMed

On northeastern Pacific coasts, Ulvaria obscura is a dominant component of subtidal "green tide" blooms, which can be harmful to marine communities, fisheries, and aquaculture facilities. U. obscura is avoided by herbivores relative to many other locally common macrophytes, which may contribute to its ability to form persistent blooms. We used a bioassay-guided fractionation method to experimentally determine the cause of reduced feeding on Ulvaria by echinoderms, molluscs, and arthropods. Our results indicated that dopamine, which constituted an average of 4.4% of the alga's dry mass, was responsible for decreased feeding by sea urchins (Strongylocentrotus droebachiensis). Subsequent experiments demonstrated that dopamine also reduced the feeding rates of snails (Littorina sitkana) and isopods (Idotea wosnesenskii). Dopamine is a catecholamine that is a common neurotransmitter in animals. The catecholamines dopamine, epinephrine (adrenaline), and norepinephrine also occur in at least 44 families of higher plants. The functions of catecholamines in plants are less well known than in animals but are likely to be diverse and include both physiological and ecological roles. Our results are the first experimental demonstration of a plant or algal catecholamine functioning as a feeding deterrent. This novel use of dopamine by Ulvaria may contribute to the formation and persistence of harmful Ulvaria blooms in northeastern Pacific coastal waters. PMID:16489461

Van Alstyne, Kathryn L; Nelson, Amorah V; Vyvyan, James R; Cancilla, Devon A

2006-06-01

193

Health Benefits of Blue-Green Algae: Prevention of Cardiovascular Disease and Nonalcoholic Fatty Liver Disease  

PubMed Central

Abstract Blue-green algae (BGA) are among the most primitive life forms on earth and have been consumed as food or medicine by humans for centuries. BGA contain various bioactive components, such as phycocyanin, carotenoids, ?-linolenic acid, fibers, and plant sterols, which can promote optimal health in humans. Studies have demonstrated that several BGA species or their active components have plasma total cholesterol and triglyceride-lowering properties due to their modulation of intestinal cholesterol absorption and hepatic lipogenic gene expression. BGA can also reduce inflammation by inhibiting the nuclear factor ? B activity, consequently reducing the production of proinflammatory cytokines. Furthermore, BGA inhibit lipid peroxidation and have free radical scavenging activity, which can be beneficial for the protection against oxidative stress. The aforementioned effects of BGA can contribute to the prevention of metabolic and inflammatory diseases. This review provides an overview of the current knowledge of the health-promoting functions of BGA against cardiovascular disease and nonalcoholic fatty liver disease, which are major health threats in the developed countries. PMID:23402636

Ku, Chai Siah; Yang, Yue; Park, Youngki

2013-01-01

194

Active Hydrocarbon Biosynthesis and Accumulation in a Green Alga, Botryococcus braunii (Race A)  

PubMed Central

Among oleaginous microalgae, the colonial green alga Botryococcus braunii accumulates especially large quantities of hydrocarbons. This accumulation may be achieved more by storage of lipids in the extracellular space rather than in the cytoplasm, as is the case for all other examined oleaginous microalgae. The stage of hydrocarbon synthesis during the cell cycle was determined by autoradiography. The cell cycle of B. braunii race A was synchronized by aminouracil treatment, and cells were taken at various stages in the cell cycle and cultured in a medium containing [14C]acetate. Incorporation of 14C into hydrocarbons was detected. The highest labeling occurred just after septum formation, when it was about 2.6 times the rate during interphase. Fluorescent and electron microscopy revealed that new lipid accumulation on the cell surface occurred during at least two different growth stages and sites of cells. Lipid bodies in the cytoplasm were not prominent in interphase cells. These lipid bodies then increased in number, size, and inclusions, reaching maximum values just before the first lipid accumulation on the cell surface at the cell apex. Most of them disappeared from the cytoplasm concomitant with the second new accumulation at the basolateral region, where extracellular lipids continuously accumulated. The rough endoplasmic reticulum near the plasma membrane is prominent in B. braunii, and the endoplasmic reticulum was often in contact with both a chloroplast and lipid bodies in cells with increasing numbers of lipid bodies. We discuss the transport pathway of precursors of extracellular hydrocarbons in race A. PMID:23794509

Hirose, Mana; Mukaida, Fukiko; Okada, Sigeru

2013-01-01

195

Molecular dynamics of the diatom thylakoid membrane under different light conditions.  

PubMed

During the last years significant progress was achieved in unraveling molecular characteristics of the thylakoid membrane of different diatoms. With the present review it is intended to summarize the current knowledge about the structural and functional changes within the thylakoid membrane of diatoms acclimated to different light conditions. This aspect is addressed on the level of the organization and regulation of light-harvesting proteins, the dissipation of excessively absorbed light energy by the process of non-photochemical quenching, and the lipid composition of diatom thylakoid membranes. Finally, a working hypothesis of the domain formation of the diatom thylakoid membrane is presented to highlight the most prominent differences of heterokontic thylakoids in comparison to vascular plants and green algae during the acclimation to low and high light conditions. PMID:21327535

Lepetit, Bernard; Goss, Reimund; Jakob, Torsten; Wilhelm, Christian

2012-03-01

196

Production of Calcite by the Green Alga Halimeda in Artificial Cretaceous Seawater  

NASA Astrophysics Data System (ADS)

The codiacean green alga Halimeda contributes 20-30% of the carbonate sediment in lagoonal areas adjacent to modern Caribbean and Indo-Pacific coral reefs. This alga is syncytial, lacking cell membranes, so that an individual thallus functions as a giant, multinucleate cell. The thallus grows as branching chains of segments interconnected by tubular filaments. A segment is formed in a single day and then filled with calcium carbonate over several days. Aragonite crystals grow within segments in the form of needles, but in some regions of a segment these are subsequently dissolved and their calcium carbonate is reprecipitated as microgranular aragonite. Some of the needles grow in a spherulitic pattern similar to that of inorganic aragonite precipitates. It has been debated whether Halimeda employs organic templates to secrete the aragonite polymorph of calcium carbonate or simply induces precipitation by taking up carbon dioxide for photosynthesis. We have found that Halimeda incrassata segments grown in seawater of modern ionic composition (Mg/Ca molar ratio = 5.2) actually contain an average of about 8% high-Mg calcite (mean 16 mol % Mg substituting for Ca). As the Mg/Ca ratio of ambient seawater is stepped down, calcite constitutes an increasing percentage of the calcium carbonate produced, and, as we have found for numerous other kinds of organisms, the Mg content of the calcite declines. For segments grown in seawater with the imputed Cretaceous Mg/Ca molar ratio of 1.5, calcite constituted, on average, 46% of the calcium carbonate (maximum, 67%) and contained about 6 mol% Mg. Experiments show that in artificial seawaters having different Mg/Ca molar ratios but otherwise having the ionic strength and chemical composition of modern seawater, aragonite can precipitate inorganically when the Mg/Ca molar ratio is above 2. The fact that Halimeda produces slightly more aragonite than calcite when the ambient Mg/Ca molar ratio is 1.5 indicates that it does exert a degree of biological control over its calcium carbonate production, but that the control is incomplete. Our growth experiments showed that there is a correlation between rate of production of carbonate and rate of production of organic matter by Halimeda, apparently because, as has been previously demonstrated, this alga's photosynthesis is enhanced by the carbon dioxide produced by its calcification. Productivity was highest in seawater of modern composition. Experiments in which either the ambient Mg/Ca ratio or the absolute concentration of Ca was held constant while the other was varied showed that an increase in either one led to a higher rate of production of both organic matter and calcium carbonate. Nonetheless, rates of production were higher in imputed Cretaceous seawater (Mg/Ca molar ratio = 1.5) than in imputed Oligocene seawater (Mg/Ca molar ratio = 2.5), presumably because in the Oligocene treatment, both of the minerals produced (high-Mg calcite and aragonite) were favored by the ambient Mg/Ca ratio, whereas in the Cretaceous treatment, 56% of the calcium carbonate was aragonite, which was not favored by the ambient Mg/Ca ratio.

Stanley, S. M.; Ries, J. B.

2006-12-01

197

Comparison of green algae Cladophora sp. and Enteromorpha sp. as potential biomonitors of chemical elements in the southern Baltic.  

PubMed

The contents of Cd, Cu, Ni, Pb, Zn, Mn, K, Na, Ca and Mg were determined in the green algae Cladophora sp. from coastal and lagoonal waters of the southern Baltic. Factor analysis demonstrated spatial differences between concentration of chemical elements. The algae from the southern Baltic contained more Na and K while the anthropogenic impact of Cu, Pb and Zn was observed in the case of Cladophora sp. and Enteromorpha sp. from the Gulf of Gdansk at the vicinity of Gdynia. This area is exposed to emission of heavy metals from municipal and industrial sources with the main contribution of shipbuilding industry and seaport. The statistical evaluation of data has demonstrated that there exists a correlation between concentrations of Cu, Pb and Zn in both green algae collected at the same time and sampling sites of the Gulf of Gdansk. Our results show that in the case of absence of one species in the investigated area it is still possible to continue successfully the biomonitoring studies with its replacing by second one, i.e. Cladophora sp. by Enteromorpha sp. and vice versa; in consequence reliable results may be obtained. PMID:17719620

Zbikowski, Rados?aw; Szefer, Piotr; Lata?a, Adam

2007-11-15

198

Evidence of Coexistence of C3 and C4 Photosynthetic Pathways in a Green-Tide-Forming Alga, Ulva prolifera  

PubMed Central

Ulva prolifera, a typical green-tide-forming alga, can accumulate a large biomass in a relatively short time period, suggesting that photosynthesis in this organism, particularly its carbon fixation pathway, must be very efficient. Green algae are known to generally perform C3 photosynthesis, but recent metabolic labeling and genome sequencing data suggest that they may also perform C4 photosynthesis, so C4 photosynthesis might be more wide-spread than previously anticipated. Both C3 and C4 photosynthesis genes were found in U. prolifera by transcriptome sequencing. We also discovered the key enzymes of C4 metabolism based on functional analysis, such as pyruvate orthophosphate dikinase (PPDK), phosphoenolpyruvate carboxylase (PEPC), and phosphoenolpyruvate carboxykinase (PCK). To investigate whether the alga operates a C4-like pathway, the expression of rbcL and PPDK and their enzyme activities were measured under various forms and intensities of stress (differing levels of salinity, light intensity, and temperature). The expression of rbcL and PPDK and their enzyme activities were higher under adverse circumstances. However, under conditions of desiccation, the expression of rbcL and ribulose-1, 5-biphosphate carboxylase (RuBPCase) activity was lower, whereas that of PPDK was higher. These results suggest that elevated PPDK activity may alter carbon metabolism and lead to a partial operation of C4-type carbon metabolism in U. prolifera, probably contributing to its wide distribution and massive, repeated blooms in the Yellow Sea. PMID:22616009

Zhang, Xiaowen; Xu, Dong; Mou, Shanli; Cao, Shaona; Zheng, Zhou; Miao, Jinlai; Ye, Naihao

2012-01-01

199

Complete sequence of the mitochondrial DNA of the red alga Porphyra purpurea. Cyanobacterial introns and shared ancestry of red and green algae.  

PubMed Central

The mitochondrial DNA (mtDNA) of Porphyra purpurea, a circular-mapping genome of 36,753 bp, has been completely sequenced. A total of 57 densely packed genes has been identified, including the basic set typically found in animals and fungi, as well as seven genes characteristic of protist and plant mtDNAs and specifying ribosomal proteins and subunits of succinate:ubiquinone oxidoreductase. The mitochondrial large subunit rRNA gene contains two group II introns that are extraordinarily similar to those found in the cyanobacterium Calothrix sp, suggesting a recent lateral intron transfer between a bacterial and a mitochondrial genome. Notable features of P. purpurea mtDNA include the presence of two 291-bp inverted repeats that likely mediate homologous recombination, resulting in genome rearrangement, and of numerous sequence polymorphisms in the coding and intergenic regions. Comparative analysis of red algal mitochondrial genomes from five different, evolutionarily distant orders reveals that rhodophyte mtDNAs are unusually uniform in size and gene order. Finally, phylogenetic analyses provide strong evidence that red algae share a common ancestry with green algae and plants. PMID:10488235

Burger, G; Saint-Louis, D; Gray, M W; Lang, B F

1999-01-01

200

Metribuzin impairs the unicell-colony transformation in the green alga Scenedesmus obliquus.  

PubMed

Active growth is a prerequisite for the formation of grazing-protective, mostly eight-celled colonies by the ubiquitous green alga Scenedesmus in response to chemical cues from zooplankton. Colonies can also be evoked by chemically quite similar manmade anionic surfactants, such as FFD-6. In this study, it was hypothesized that growth-inhibiting concentrations of the herbicide metribuzin impair the ability of Scenedesmus obliquus to form colonies in response to the surfactant morphogen FFD-6. The results confirmed that the formation of colonies in S. obliquus was hampered by metribuzin. EC50 values of metribuzin for colony inhibition (approximately 11 ?g L(-1)) were similar to those for growth and photosynthesis inhibition (12-25 ?g metribuzinL(-1)). In the absence of the colony-inducing surfactant FFD-6, S. obliquus populations were comprised of 92% unicells, having on average 1.2 cells per colony at all tested metribuzin concentrations (0-100 ?g L(-1)). In contrast, in the presence of FFD-6 and at low metribuzin concentrations (0 and 5 ?g L(-1)), S. obliquus had more than five cells per colony with a high portion of eight-celled colonies. However, increasing concentrations of metribuzin decreased the number of colonies in the FFD-6-exposed populations and caused them to remain mostly unicellular at the highest concentrations (50 and 100 ?g L(-1)). This study revealed that metribuzin impeded growth and by doing so, also obstructed the possibility for unicellular Scenedesmus to form colonies. Consequently, an increase in mortality of Scenedesmus from grazing is expected. PMID:20971494

Lürling, M

2011-01-01

201

Chlorovirus: a genus of Phycodnaviridae that infects certain chlorella-like green algae.  

PubMed

SUMMARY Taxonomy: Chlorella viruses are assigned to the family Phycodnaviridae, genus Chlorovirus, and are divided into three species: Chlorella NC64A viruses, Chlorella Pbi viruses and Hydra viridis Chlorella viruses. Chlorella viruses are large, icosahedral, plaque-forming, dsDNA viruses that infect certain unicellular, chlorella-like green algae. The type member is Paramecium bursaria chlorella virus 1 (PBCV-1). Physical properties: Chlorella virus particles are large (molecular weight approximately 1 x 10(9) Da) and complex. The virion of PBCV-1 contains more than 100 different proteins; the major capsid protein, Vp54, comprises approximately 40% of the virus protein. Cryoelectron microscopy and three-dimensional image reconstruction of PBCV-1 virions indicate that the outer glycoprotein-containing capsid shell is icosahedral and surrounds a lipid bilayered membrane. The diameter of the viral capsid ranges from 1650 A along the two- and three-fold axes to 1900 A along the five-fold axis. The virus contains 5040 copies of Vp54, and the triangulation number is 169. The PBCV-1 genome is a linear, 330 744-bp, non-permuted dsDNA with covalently closed hairpin ends. The PBCV-1 genome contains approximately 375 protein-encoding genes and 11 tRNA genes. About 50% of the protein-encoding genes match proteins in the databases. Hosts: Chlorella NC64A and Chlorella Pbi, the hosts for NC64A viruses and Pbi viruses, respectively, are endosymbionts of the protozoan Paramecium bursaria. However, they can be grown in the laboratory free of both the paramecium and the virus. These two chlorella species are hosts to viruses that have been isolated from fresh water collected around the world. The host for hydra chlorella virus, a symbiotic chlorella from Hydra viridis, has not been grown independently of its host; thus the virus can only be obtained from chlorella cells freshly released from hydra. PMID:20565652

Kang, Ming; Dunigan, David D; VAN Etten, James L

2005-05-01

202

A rapid, modular and marker-free chloroplast expression system for the green alga Chlamydomonas reinhardtii.  

PubMed

In search of alternative expression platforms heterologous protein production in microalgae has gained increasing importance in the last years. Particularly, the chloroplast of the green alga Chlamydomonas reinhardtii has been adopted to successfully express foreign proteins like vaccines and antibodies. However, when compared with other expression systems, the development of the algal chloroplast to a powerful production platform for recombinant proteins is still in its early stages. In an effort to further improve methods for a reliable and rapid generation of transplastomic Chlamydomonas strains we constructed the key plasmid pMM2 containing the psbA gene and a multiple cloning site for foreign gene insertion. The psbA gene allows a marker-free selection procedure using as a recipient the Fud7 strain of Chlamydomonas, which grows on media containing acetate as a carbon source, but is unable to grow photoautotrophically due to the lack of an intact psbA gene. Biolistic transformation of Fud7 with vectors containing this gene restores photoautotrophic growth and thus permits selection in the light on media without carbon sources and antibiotics. The multiple cloning site with a BsaI recognition sequence allows type IIs restriction enzyme-based modular cloning which rapidly generates new gene constructs without sequences, which could influence the expression and characteristics of the foreign protein. In order to demonstrate the feasibility of this approach, a codon optimized version of the gene for the bacterial protein MPT64 has been integrated into the plastome. Several strains with different promoter/UTR combinations show a stable expression of the HA tagged MPT64 protein in Chlamydomonas chloroplasts. PMID:25554634

Bertalan, Ivo; Munder, Matthias C; Weiß, Caroline; Kopf, Judith; Fischer, Dirk; Johanningmeier, Udo

2015-02-10

203

Functional Rearrangement of the Light-Harvesting Antenna upon State Transitions in a Green Alga.  

PubMed

State transitions in the green alga Chlamydomonas reinhardtii serve to balance excitation energy transfer to photosystem I (PSI) and to photosystem II (PSII) and possibly play a role as a photoprotective mechanism. Thus, light-harvesting complex II (LHCII) can switch between the photosystems consequently transferring more excitation energy to PSII (state 1) or to PSI (state 2) or can end up in LHCII-only domains. In this study, low-temperature (77 K) steady-state and time-resolved fluorescence measured on intact cells of Chlamydomonas reinhardtii shows that independently of the state excitation energy transfer from LHCII to PSI or to PSII occurs on two main timescales of <15 ps and ?100 ps. Moreover, in state 1 almost all LHCIIs are functionally connected to PSII, whereas the transition from state 1 to a state 2 chemically locked by 0.1 M sodium fluoride leads to an almost complete functional release of LHCIIs from PSII. About 2/3 of the released LHCIIs transfer energy to PSI and ?1/3 of the released LHCIIs form a component designated X-685 peaking at 685 nm that decays with time constants of 0.28 and 5.8 ns and does not transfer energy to PSI or to PSII. A less complete state 2 was obtained in cells incubated under anaerobic conditions without chemical locking. In this state about half of all LHCIIs remained functionally connected to PSII, whereas the remaining half became functionally connected to PSI or formed X-685 in similar amounts as with chemical locking. We demonstrate that X-685 originates from LHCII domains not connected to a photosystem and that its presence introduces a change in the interpretation of 77 K steady-state fluorescence emission measured upon state transitions in Chalamydomonas reinhardtii. PMID:25606675

Wlodarczyk, Lucyna M; Snellenburg, Joris J; Ihalainen, Janne A; van Grondelle, Rienk; van Stokkum, Ivo H M; Dekker, Jan P

2015-01-20

204

Active CO sub 2 transport by the green alga Chlamydomonas reinhardtii  

SciTech Connect

Mass spectrometric measurements of dissolved free {sup 13}CO{sub 2} were used to monitor CO{sub 2} uptake by air grown (low CO{sub 2}) cells and protoplasts from the green alga Chlamydomonas reinhardtii. In the presence of 50 micromolar dissolved inorganic carbon and light, protoplasts which had been washed free of external carbonic anhydrase reduced the {sup 13}CO{sub 2} concentration in the medium to close to zero. Similar results were obtained with low CO{sub 2} cells treated with 50 micromolar acetazolamide. Addition of carbonic anhydrase to protoplasts after the period of rapid CO{sub 2} uptake revealed that the removal of CO{sub 2} from the medium in the light was due to selective and active CO{sub 2} transport rather than uptake of total dissolved inorganic carbon. In the light, low CO{sub 2} cells and protoplasts incubated with carbonic anhydrase took up CO{sub 2} at an apparently low rate which reflected the uptake of total dissolved inorganic carbon. No net CO{sub 2} uptake occurred in the dark. Measurement of chlorophyll a fluorescence yield with low CO{sub 2} cells and washed protoplasts showed that variable fluorescence was mainly influenced by energy quenching which was reciprocally related to photosynthetic activity with its highest value at the CO{sub 2} compensation point. During the linear uptake of CO{sub 2}, low CO{sub 2} cells and protoplasts incubated with carbonic anhydrase showed similar rates of net O{sub 2} evolution.

Sueltemeyer, D.F.; Miller, A.G.; Espie, G.S.; Fock, H.P.; Canvin, D.T. (Queen's Univ., Kingston, Ontario (Canada) Univ. of Kaiserslautern (West Germany))

1989-04-01

205

Molecular phylogeny of conjugating green algae (Zygnemophyceae, Streptophyta) inferred from SSU rDNA sequence comparisons.  

PubMed

Nuclear-encoded SSU rDNA sequences have been obtained from 64 strains of conjugating green algae (Zygnemophyceae, Streptophyta, Viridiplantae). Molecular phylogenetic analyses of 90 SSU rDNA sequences of Viridiplantae (inciuding 78 from the Zygnemophyceae) were performed using complex evolutionary models and maximum likelihood, distance, and maximum parsimony methods. The significance of the results was tested by bootstrap analyses, deletion of long-branch taxa, relative rate tests, and Kishino-Hasegawa tests with user-defined trees. All results support the monophyly of the class Zygnemophyceae and of the order Desmidiales. The second order, Zygnematales, forms a series of early-branching clades in paraphyletic succession, with the two traditional families Mesotaeniaceae and Zygnemataceae not recovered as lineages. Instead, a long-branch Spirogyra/Sirogonium clade and the later-diverging Netrium and Roya clades represent independent clades. Within the order Desmidiales, the families Gonatozygaceae and Closteriaceae are monophyletic, whereas the Peniaceae (represented only by Penium margaritaceum) and the Desmidiaceae represent a single weakly supported lineage. Within the Desmidiaceae short internal branches and varying rates of sequence evolution among taxa reduce the phylogenetic resolution significantly. The SSU rDNA-based phylogeny is largely congruent with a published analysis of the rbcL phylogeny of the Zygnemophyceae (McCourt et al. 2000) and is also in general agreement with classification schemes based on cell wall ultrastructure. The extended taxon sampling at the subgenus level provides solid evidence that many genera in the Zygnemophyceae are not monophyletic and that the genus concept in the group needs to be revised. PMID:12569426

Gontcharov, Andrey A; Marin, Birger A; Melkonian, Michael A

2003-01-01

206

Phragmoplast of the green alga Spirogyra is functionally distinct from the higher plant phragmoplast  

PubMed Central

Cytokinesis in the green alga Spirogyra (Zygnemataceae) is characterized by centripetal growth of a septum, which impinges on a persistent, centrifugally expanding telophase spindle, leading to a phragmoplast-like structure of potential phylogenetic significance (Fowke, L. C., and J. D. Pickett-Heaps. 1969. J. Phycol. 5:273-281). Combining fluorescent tagging of the cytoskeleton in situ and video- enhanced differential interference contrast microscopy of live cells, the process of cytokinesis was investigated with emphasis on cytoskeletal reorganization and concomitant redistribution of organelles. Based on a sequence of cytoskeletal arrangements and the effects of cytoskeletal inhibitors thereon, cytokinetic progression could be divided into three functional stages with respect to the contribution of microfilaments (MFs) and microtubules (MTs): (1) Initiation: in early prophase, a cross wall initial was formed independently of MFs and MTs at the presumptive site of wall growth. (2) Septum ingrowth: numerous organelles accumulated at the cross wall initial concomitant with reorganization of the extensive peripheral interphase MF array into a distinct circumferential MF array. This array guided the ingrowing septum until it contacted the expanding interzonal MT array. (3) Cross wall closure: MFs at the growing edge of the septum coaligned with and extended along the interzonal MTs toward the daughter nuclei. Thus, actin-based transportation of small organelles during this third stage occurred, in part, along a scaffold previously deployed in space by MTs. Displacement of the nuclei- associated interzonal MT array by centrifugation and depolymerization of the phragmoplast-like structure showed that the success of cytokinesis at the third stage depends on the interaction of both MF and MT cytoskeletons. Important features of the phragmoplast-like structure in Spirogyra were different from the higher plant phragmoplast: in particular, MFs were responsible for the positioning of organelles at the fusion site, contrary to the proposed role of MTs in the higher plant phragmoplast. PMID:7559758

1995-01-01

207

Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements.  

PubMed

The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 microg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 microg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener. PMID:10811570

Gilroy, D J; Kauffman, K W; Hall, R A; Huang, X; Chu, F S

2000-05-01

208

Structural studies of ?-carbonic anhydrase from the green alga Coccomyxa: inhibitor complexes with anions and acetazolamide.  

PubMed

The ?-class carbonic anhydrases (?-CAs) are widely distributed among lower eukaryotes, prokaryotes, archaea, and plants. Like all CAs, the ?-enzymes catalyze an important physiological reaction, namely the interconversion between carbon dioxide and bicarbonate. In plants the enzyme plays an important role in carbon fixation and metabolism. To further explore the structure-function relationship of ?-CA, we have determined the crystal structures of the photoautotroph unicellular green alga Coccomyxa ?-CA in complex with five different inhibitors: acetazolamide, thiocyanate, azide, iodide, and phosphate ions. The tetrameric Coccomyxa ?-CA structure is similar to other ?-CAs but it has a 15 amino acid extension in the C-terminal end, which stabilizes the tetramer by strengthening the interface. Four of the five inhibitors bind in a manner similar to what is found in complexes with ?-type CAs. Iodide ions, however, make contact to the zinc ion via a zinc-bound water molecule or hydroxide ion--a type of binding mode not previously observed in any CA. Binding of inhibitors to Coccomyxa ?-CA is mediated by side-chain movements of the conserved residue Tyr-88, extending the width of the active site cavity with 1.5-1.8 Ĺ. Structural analysis and comparisons with other ?- and ?-class members suggest a catalytic mechanism in which the movements of Tyr-88 are important for the CO(2)-HCO(3)(-) interconversion, whereas a structurally conserved water molecule that bridges residues Tyr-88 and Gln-38, seems important for proton transfer, linking water molecules from the zinc-bound water to His-92 and buffer molecules. PMID:22162771

Huang, Shenghua; Hainzl, Tobias; Grundström, Christin; Forsman, Cecilia; Samuelsson, Göran; Sauer-Eriksson, A Elisabeth

2011-01-01

209

Structural Studies of ?-Carbonic Anhydrase from the Green Alga Coccomyxa: Inhibitor Complexes with Anions and Acetazolamide  

PubMed Central

The ?-class carbonic anhydrases (?-CAs) are widely distributed among lower eukaryotes, prokaryotes, archaea, and plants. Like all CAs, the ?-enzymes catalyze an important physiological reaction, namely the interconversion between carbon dioxide and bicarbonate. In plants the enzyme plays an important role in carbon fixation and metabolism. To further explore the structure-function relationship of ?-CA, we have determined the crystal structures of the photoautotroph unicellular green alga Coccomyxa ?-CA in complex with five different inhibitors: acetazolamide, thiocyanate, azide, iodide, and phosphate ions. The tetrameric Coccomyxa ?-CA structure is similar to other ?-CAs but it has a 15 amino acid extension in the C-terminal end, which stabilizes the tetramer by strengthening the interface. Four of the five inhibitors bind in a manner similar to what is found in complexes with ?-type CAs. Iodide ions, however, make contact to the zinc ion via a zinc-bound water molecule or hydroxide ion — a type of binding mode not previously observed in any CA. Binding of inhibitors to Coccomyxa ?-CA is mediated by side-chain movements of the conserved residue Tyr-88, extending the width of the active site cavity with 1.5-1.8 Ĺ. Structural analysis and comparisons with other ?- and ?-class members suggest a catalytic mechanism in which the movements of Tyr-88 are important for the CO2-HCO3- interconversion, whereas a structurally conserved water molecule that bridges residues Tyr-88 and Gln-38, seems important for proton transfer, linking water molecules from the zinc-bound water to His-92 and buffer molecules. PMID:22162771

Huang, Shenghua; Hainzl, Tobias; Grundström, Christin; Forsman, Cecilia; Samuelsson, Göran; Sauer-Eriksson, A. Elisabeth

2011-01-01

210

Evolution and metabolic significance of the urea cycle in photosynthetic diatoms.  

PubMed

Diatoms dominate the biomass of phytoplankton in nutrient-rich conditions and form the basis of some of the world's most productive marine food webs. The diatom nuclear genome contains genes with bacterial and plastid origins as well as genes of the secondary endosymbiotic host (the exosymbiont), yet little is known about the relative contribution of each gene group to diatom metabolism. Here we show that the exosymbiont-derived ornithine-urea cycle, which is similar to that of metazoans but is absent in green algae and plants, facilitates rapid recovery from prolonged nitrogen limitation. RNA-interference-mediated knockdown of a mitochondrial carbamoyl phosphate synthase impairs the response of nitrogen-limited diatoms to nitrogen addition. Metabolomic analyses indicate that intermediates in the ornithine-urea cycle are particularly depleted and that both the tricarboxylic acid cycle and the glutamine synthetase/glutamate synthase cycles are linked directly with the ornithine-urea cycle. Several other depleted metabolites are generated from ornithine-urea cycle intermediates by the products of genes laterally acquired from bacteria. This metabolic coupling of bacterial- and exosymbiont-derived proteins seems to be fundamental to diatom physiology because the compounds affected include the major diatom osmolyte proline and the precursors for long-chain polyamines required for silica precipitation during cell wall formation. So far, the ornithine-urea cycle is only known for its essential role in the removal of fixed nitrogen in metazoans. In diatoms, this cycle serves as a distribution and repackaging hub for inorganic carbon and nitrogen and contributes significantly to the metabolic response of diatoms to episodic nitrogen availability. The diatom ornithine-urea cycle therefore represents a key pathway for anaplerotic carbon fixation into nitrogenous compounds that are essential for diatom growth and for the contribution of diatoms to marine productivity. PMID:21562560

Allen, Andrew E; Dupont, Christopher L; Oborník, Miroslav; Horák, Aleš; Nunes-Nesi, Adriano; McCrow, John P; Zheng, Hong; Johnson, Daniel A; Hu, Hanhua; Fernie, Alisdair R; Bowler, Chris

2011-05-12

211

System Responses to Equal Doses of Photosynthetically Usable Radiation of Blue, Green, and Red Light in the Marine Diatom Phaeodactylum tricornutum  

PubMed Central

Due to the selective attenuation of solar light and the absorption properties of seawater and seawater constituents, free-floating photosynthetic organisms have to cope with rapid and unpredictable changes in both intensity and spectral quality. We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions. PMID:25470731

Valle, Kristin Collier; Nymark, Marianne; Aamot, Inga; Hancke, Kasper; Winge, Per; Andresen, Kjersti; Johnsen, Geir; Brembu, Tore; Bones, Atle M.

2014-01-01

212

Evolutionary relatedness does not predict competition and co-occurrence in natural or experimental communities of green algae.  

PubMed

The competition-relatedness hypothesis (CRH) predicts that the strength of competition is the strongest among closely related species and decreases as species become less related. This hypothesis is based on the assumption that common ancestry causes close relatives to share biological traits that lead to greater ecological similarity. Although intuitively appealing, the extent to which phylogeny can predict competition and co-occurrence among species has only recently been rigorously tested, with mixed results. When studies have failed to support the CRH, critics have pointed out at least three limitations: (i) the use of data poor phylogenies that provide inaccurate estimates of species relatedness, (ii) the use of inappropriate statistical models that fail to detect relationships between relatedness and species interactions amidst nonlinearities and heteroskedastic variances, and (iii) overly simplified laboratory conditions that fail to allow eco-evolutionary relationships to emerge. Here, we address these limitations and find they do not explain why evolutionary relatedness fails to predict the strength of species interactions or probabilities of coexistence among freshwater green algae. First, we construct a new data-rich, transcriptome-based phylogeny of common freshwater green algae that are commonly cultured and used for laboratory experiments. Using this new phylogeny, we re-analyse ecological data from three previously published laboratory experiments. After accounting for the possibility of nonlinearities and heterogeneity of variances across levels of relatedness, we find no relationship between phylogenetic distance and ecological traits. In addition, we show that communities of North American green algae are randomly composed with respect to their evolutionary relationships in 99% of 1077 lakes spanning the continental United States. Together, these analyses result in one of the most comprehensive case studies of how evolutionary history influences species interactions and community assembly in both natural and experimental systems. Our results challenge the generality of the CRH and suggest it may be time to re-evaluate the validity and assumptions of this hypothesis. PMID:25473009

Alexandrou, Markos A; Cardinale, Bradley J; Hall, John D; Delwiche, Charles F; Fritschie, Keith; Narwani, Anita; Venail, Patrick A; Bentlage, Bastian; Pankey, M Sabrina; Oakley, Todd H

2015-01-22

213

A geometrical approach explains Lake Ball (Marimo) formations in the green alga, Aegagropila linnaei  

PubMed Central

An extremely rare alga, Aegagropila linnaei, is known for its beautiful spherical filamentous aggregations called Lake Ball (Marimo). It has long been a mystery in biology as to why this species forms 3D ball-like aggregations. This alga also forms two-dimensional mat-like aggregations. Here we show that forming ball-like aggregations is an adaptive strategy to increase biomass in the extremely limited environments suitable for growth of this alga. We estimate the maximum biomass attained by ball colonies and compare it to that attained by mat colonies. As a result, a ball colony can become larger in areal biomass than the mat colony. In the two large ball colonies studied so far, they actually have larger biomasses than the mat colonies. The uniqueness of Lake Balls in nature seems to be due to the rarity of such environmental conditions. This implies that the conservation of this alga is difficult, but important. PMID:24441685

Togashi, Tatsuya; Sasaki, Hironobu; Yoshimura, Jin

2014-01-01

214

Blue-green algae (Arthrospira platensis) as an ingredient in pasta: free radical scavenging activity, sensory and cooking characteristics evaluation.  

PubMed

The effects of semolina enrichment with blue-green algae (Arthrospira platensis) at three different levels (1, 2 and 3 g/100 g of semolina) on the colour, cooking properties, firmness, free radical scavenging activity and sensory characteristics of pasta are reported. Microalgae addition resulted in higher swelling index and lower cooking loss than the control sample. A significant increase in pasta firmness was evidenced with an increase of added microalgae due to structural reinforcement. In addition to colouring, the use of A. platensis (2 g/100 g of semolina) can enhance the sensory quality and nutraceutical potential as evaluated by free radical scavenging activity of pasta. PMID:21568819

Zouari, Nacim; Abid, Mouna; Fakhfakh, Nahed; Ayadi, M A; Zorgui, Lazhar; Ayadi, Moez; Attia, Hamadi

2011-12-01

215

Cloning and expression study of a putative carotene biosynthesis related (cbr) gene from the halotolerant green alga Dunaliella salina.  

PubMed

Dunaliella salina, a unicelluar green alga that can tolerate an extreme variation of salt concentration is being studied as a model system to analyze the tolerance of abiotic stresses at the molecular level. Upon abnormal NaCl levels, new transcripts were abundantly expressed in cells of the alga. EST gene discovery efforts utilizing salt-shock cells had identified one cDNA designated Dscbr (GenBank accession no. DQ867041) with significant similarity to a carotene biosynthesis related gene (cbr) from Dunaliella bardawil and to early light inducible genes (elip) of higher plants. Dscbr was 976 bp in length, encoding a 190 amino acid deduced polypeptide (DsCBR) with a predicted molecular mass of 19.9 kDa and pI of 9.0. The three dimensional structure of DsCBR modeled by computer homology modeling techniques showed that the protein possessed three predicted transmembrane helices and six conserved pigment-binding residues. Real-Time Quantitative PCR clearly demonstrated that Dscbr mRNA can be rapidly induced by high light intensity and salt shocks. The results presented in this work are consistent with the earlier proposal (Jin et al. 2001 Biochim Biophys Acta 1506:244-259, 2003 Plant Physiol 132:352-364) that the DsCBR protein is an adaptive response to stress-induced photodamage within the alga chloroplast, and plays a key role in the protection and/or repair of the photosynthetic apparatus. PMID:17562223

Chen, Chen; Bai, Lin Han; Qiao, Dai Rong; Xu, Hui; Dong, Gui Ling; Ruan, Kun; Huang, Fei; Cao, Yi

2008-09-01

216

The GC-Rich Mitochondrial and Plastid Genomes of the Green Alga Coccomyxa Give Insight into the Evolution of Organelle DNA Nucleotide Landscape  

PubMed Central

Most of the available mitochondrial and plastid genome sequences are biased towards adenine and thymine (AT) over guanine and cytosine (GC). Examples of GC-rich organelle DNAs are limited to a small but eclectic list of species, including certain green algae. Here, to gain insight in the evolution of organelle nucleotide landscape, we present the GC-rich mitochondrial and plastid DNAs from the trebouxiophyte green alga Coccomyxa sp. C-169. We compare these sequences with other GC-rich organelle DNAs and argue that the forces biasing them towards G and C are nonadaptive and linked to the metabolic and/or life history features of this species. The Coccomyxa organelle genomes are also used for phylogenetic analyses, which highlight the complexities in trying to resolve the interrelationships among the core chlorophyte green algae, but ultimately favour a sister relationship between the Ulvophyceae and Chlorophyceae, with the Trebouxiophyceae branching at the base of the chlorophyte crown. PMID:21887287

Smith, David Roy; Burki, Fabien; Yamada, Takashi; Grimwood, Jane; Grigoriev, Igor V.; Van Etten, James L.; Keeling, Patrick J.

2011-01-01

217

The GC-Rich Mitochondrial and Plastid Genomes of the Green Alga Coccomyxa Give Insight into the Evolution of Organelle DNA Nucleotide Landscape  

SciTech Connect

Most of the available mitochondrial and plastid genome sequences are biased towards adenine and thymine (AT) over guanine and cytosine (GC). Examples of GC-rich organelle DNAs are limited to a small but eclectic list of species, including certain green algae. Here, to gain insight in the evolution of organelle nucleotide landscape, we present the GC-rich mitochondrial and plastid DNAs from the trebouxiophyte green alga Coccomyxa sp. C-169. We compare these sequences with other GC-rich organelle DNAs and argue that the forces biasing them towards G and C are nonadaptive and linked to the metabolic and/or life history features of this species. The Coccomyxa organelle genomes are also used for phylogenetic analyses, which highlight the complexities in trying to resolve the interrelationships among the core chlorophyte green algae, but ultimately favour a sister relationship between the Ulvophyceae and Chlorophyceae, with the Trebouxiophyceae branching at the base of the chlorophyte crown.

Smith, David Roy; Burki, Fabien; Yamada, Takashi; Grimwood, Jane; Grigoriev, Igor V.; Van Etten, James L.; Keeling, Patrick J.

2011-05-13

218

The Mitochondrial Genome of Chara vulgaris: Insights into the Mitochondrial DNA Architecture of the Last Common Ancestor of Green Algae and Land PlantsW?  

PubMed Central

Mitochondrial DNA (mtDNA) has undergone radical changes during the evolution of green plants, yet little is known about the dynamics of mtDNA evolution in this phylum. Land plant mtDNAs differ from the few green algal mtDNAs that have been analyzed to date by their expanded size, long spacers, and diversity of introns. We have determined the mtDNA sequence of Chara vulgaris (Charophyceae), a green alga belonging to the charophycean order (Charales) that is thought to be the most closely related alga to land plants. This 67,737-bp mtDNA sequence, displaying 68 conserved genes and 27 introns, was compared with those of three angiosperms, the bryophyte Marchantia polymorpha, the charophycean alga Chaetosphaeridium globosum (Coleochaetales), and the green alga Mesostigma viride. Despite important differences in size and intron composition, Chara mtDNA strikingly resembles Marchantia mtDNA; for instance, all except 9 of 68 conserved genes lie within blocks of colinear sequences. Overall, our genome comparisons and phylogenetic analyses provide unequivocal support for a sister-group relationship between the Charales and the land plants. Only four introns in land plant mtDNAs appear to have been inherited vertically from a charalean algar ancestor. We infer that the common ancestor of green algae and land plants harbored a tightly packed, gene-rich, and relatively intron-poor mitochondrial genome. The group II introns in this ancestral genome appear to have spread to new mtDNA sites during the evolution of bryophytes and charalean green algae, accounting for part of the intron diversity found in Chara and land plant mitochondria. PMID:12897260

Turmel, Monique; Otis, Christian; Lemieux, Claude

2003-01-01

219

Metabolite profiling and integrative modeling reveal metabolic constraints for carbon partitioning under nitrogen starvation in the green algae Haematococcus pluvialis.  

PubMed

The green alga Hematococcus pluvialis accumulates large amounts of the antioxidant astaxanthin under inductive stress conditions, such as nitrogen starvation. The response to nitrogen starvation and high light leads to the accumulation of carbohydrates and fatty acids as well as increased activity of the tricarboxylic acid cycle. Although the behavior of individual pathways has been well investigated, little is known about the systemic effects of the stress response mechanism. Here we present time-resolved metabolite, enzyme activity, and physiological data that capture the metabolic response of H. pluvialis under nitrogen starvation and high light. The data were integrated into a putative genome-scale model of the green alga to in silico test hypotheses of underlying carbon partitioning. The model-based hypothesis testing reinforces the involvement of starch degradation to support fatty acid synthesis in the later stages of the stress response. In addition, our findings support a possible mechanism for the involvement of the increased activity of the tricarboxylic acid cycle in carbon repartitioning. Finally, the in vitro experiments and the in silico modeling presented here emphasize the predictive power of large scale integrative approaches to pinpoint metabolic adjustment to changing environments. PMID:25183014

Recht, Lee; Töpfer, Nadine; Batushansky, Albert; Sikron, Noga; Gibon, Yves; Fait, Aaron; Nikoloski, Zoran; Boussiba, Sammy; Zarka, Aliza

2014-10-31

220

Ribosomal protein L10 is encoded in the mitochondrial genome of many land plants and green algae  

PubMed Central

Background The mitochondrial genomes of plants generally encode 30-40 identified protein-coding genes and a large number of lineage-specific ORFs. The lack of wide conservation for most ORFs suggests they are unlikely to be functional. However, an ORF, termed orf-bryo1, was recently found to be conserved among bryophytes suggesting that it might indeed encode a functional mitochondrial protein. Results From a broad survey of land plants, we have found that the orf-bryo1 gene is also conserved in the mitochondria of vascular plants and charophycean green algae. This gene is actively transcribed and RNA edited in many flowering plants. Comparative sequence analysis and distribution of editing suggests that it encodes ribosomal protein L10 of the large subunit of the ribosome. In several lineages, such as crucifers and grasses, where the rpl10 gene has been lost from the mitochondrion, we suggest that a copy of the nucleus-encoded chloroplast-derived rpl10 gene may serve as a functional replacement. Conclusion Despite the fact that there are now over 20 mitochondrial genome sequences for land plants and green algae, this gene has remained unidentified and largely undetected until now because of the unlikely coincidence that most of the earlier sequences were from the few lineages that lack the intact gene. These results illustrate the power of comparative sequencing to identify novel genomic features. PMID:19917118

2009-01-01

221

Different fates of the chloroplast tufA gene following its transfer to the nucleus in green algae.  

PubMed Central

Previous work suggested that the tufA gene, encoding protein synthesis elongation factor Tu, was transferred from the chloroplast to the nucleus within the green algal lineage giving rise to land plants. In this report we investigate the timing and mode of transfer by examining chloroplast and nuclear DNA from the three major classes of green algae, with emphasis on the class Charophyceae, the proposed sister group to land plants. Filter hybridizations reveal a chloroplast tufA gene in all Ulvophyceae and Chlorophyceae and in some but not all Charophyceae. One charophycean alga, Coleochaete orbicularis, is shown to contain an intact but highly divergent chloroplast tufA gene, whose product is predicted to be non-functional in protein synthesis. We propose that a copy of the tufA gene was functionally transferred from the chloroplast to the nucleus early in the evolution of the Charophyceae, with chloroplast copies of varying function being retained in some but not all of the subsequently diverging lineages. This proposal is supported by the demonstration of multiple tufA-like sequences in Coleochaete nuclear DNA and in nuclear DNA from all other Charophyceae examined. Images PMID:2371274

Baldauf, S L; Manhart, J R; Palmer, J D

1990-01-01

222

New “missing link” genus of the colonial volvocine green algae gives insights into the evolution of oogamy  

PubMed Central

Background The evolution of oogamy from isogamy, an important biological event, can be summarized as follows: morphologically similar gametes (isogametes) differentiated into small “male” and large “female” motile gametes during anisogamy, from which immotile female gametes (eggs) evolved. The volvocine green algae represent a model lineage to study this type of sex evolution and show two types of gametic unions: conjugation between isogametes outside the parental colonies (external fertilization during isogamy) and fertilization between small motile gametes (sperm) and large gametes (eggs) inside the female colony (internal fertilization during anisogamy and oogamy). Although recent cultural studies on volvocine algae revealed morphological diversity and molecular genetic data of sexual reproduction, an intermediate type of union between these two gametic unions has not been identified. Results We identified a novel colonial volvocine genus, Colemanosphaera, which produces bundles of spindle-shaped male gametes through successive divisions of colonial cells. Obligately anisogamous conjugation between male and female motile gametes occurred outside the female colony (external fertilization during anisogamy). This new genus contains 16- or 32-celled spheroidal colonies similar to those of the volvocine genera Yamagishiella and Eudorina. However, Colemanosphaera can be clearly distinguished from these two genera based on its sister phylogenetic position to the enigmatic flattened colonial volvocine Platydorina and external fertilization during anisogamy. Two species of Colemanosphaera were found in a Japanese lake; these species are also distributed in European freshwaters based on a published sequence of an Austrian strain and the original description of Pandorina charkowiensis from Ukraine. Conclusions Based on phylogeny and morphological data, this novel genus exhibits a missing link between Platydorina and the typical spheroidal colonial volvocine members such as Pandorina or Yamagishiella. Considering the external obligate anisogamy, oogamy evolution may have been preceded by the transition from external to internal fertilization during anisogamy within the volvocine green algae. PMID:24589311

2014-01-01

223

Biosynthetic Pathway and Health Benefits of Fucoxanthin, an Algae-Specific Xanthophyll in Brown Seaweeds  

PubMed Central

Fucoxanthin is the main carotenoid produced in brown algae as a component of the light-harvesting complex for photosynthesis and photoprotection. In contrast to the complete elucidation of the carotenoid biosynthetic pathways in red and green algae, the biosynthetic pathway of fucoxanthin in brown algae is not fully understood. Recently, two models for the fucoxanthin biosynthetic pathway have been proposed in unicellular diatoms; however, there is no such information for the pathway in brown seaweeds to date. Here, we propose a biosynthetic pathway for fucoxanthin in the brown seaweed, Ectocarpus siliculosus, derived from comparison of carotenogenic genes in its sequenced genome with those in the genomes of two diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum. Currently, fucoxanthin is receiving attention, due to its potential benefits for human health. Therefore, new knowledge regarding the medical and nutraceutical properties of fucoxanthin from brown seaweeds is also summarized here. PMID:23820585

Mikami, Koji; Hosokawa, Masashi

2013-01-01

224

Biosorption of Chromium(VI) From Aqueous solutions by green algae spirogyra species  

Microsoft Academic Search

Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters. Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species. Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH. Equilibrium

V. K. Gupta; A. K. Shrivastava; Neeraj Jain

2001-01-01

225

Transcriptomics of Desiccation Tolerance in the Streptophyte Green Alga Klebsormidium Reveal a Land Plant-Like Defense Reaction  

PubMed Central

Background Water loss has significant effects on physiological performance and survival rates of algae. However, despite the prominent presence of aeroterrestrial algae in terrestrial habitats, hardly anything is known about the molecular events that allow aeroterrestrial algae to survive harsh environmental conditions. We analyzed the transcriptome and physiology of a strain of the alpine aeroterrestrial alga Klebsormidium crenulatum under control and strong desiccation-stress conditions. Principal Findings For comparison we first established a reference transcriptome. The high-coverage reference transcriptome includes about 24,183 sequences (1.5 million reads, 636 million bases). The reference transcriptome encodes for all major pathways (energy, carbohydrates, lipids, amino acids, sugars), nearly all deduced pathways are complete or missing only a few transcripts. Upon strong desiccation, more than 7000 transcripts showed changes in their expression levels. Most of the highest up-regulated transcripts do not show similarity to known viridiplant proteins, suggesting the existence of some genus- or species-specific responses to desiccation. In addition, we observed the up-regulation of many transcripts involved in desiccation tolerance in plants (e.g. proteins similar to those that are abundant in late embryogenesis (LEA), or proteins involved in early response to desiccation ERD), and enzymes involved in the biosynthesis of the raffinose family of oligosaccharides (RFO) known to act as osmolytes). Major physiological shifts are the up-regulation of transcripts for photosynthesis, energy production, and reactive oxygen species (ROS) metabolism, which is supported by elevated cellular glutathione content as revealed by immunoelectron microscopy as well as an increase in total antiradical power. However, the effective quantum yield of Photosystem II and CO2 fixation decreased sharply under the applied desiccation stress. In contrast, transcripts for cell integrative functions such as cell division, DNA replication, cofactor biosynthesis, and amino acid biosynthesis were down-regulated. Significance This is the first study investigating the desiccation transcriptome of a streptophyte green alga. Our results indicate that the cellular response is similar to embryophytes, suggesting that embryophytes inherited a basic cellular desiccation tolerance from their streptophyte predecessors. PMID:25340847

Holzinger, Andreas; Kaplan, Franziska; Blaas, Kathrin; Zechmann, Bernd; Komsic-Buchmann, Karin; Becker, Burkhard

2014-01-01

226

Antitumor activity of marine algae  

Microsoft Academic Search

Powdered tissue from 46 species of air-dried marine algae (four green, 21 brown and 21 red algae) were screened for antitumor activity. Significant activity against Ehrlich carcinoma was found in the brown algae Scytosiphon lomentaria (69.8% inhibition), Lessonia nigrescens (60.0%), Laminaria japonica (57.6%), Sargassum ringgoldianum (46.5%), the red algae Porphyra yezoensis (53.2%) and Eucheuma gelatinae (52.1%) and the green alga

Hiroyuki Noda; Hideomi Amano; Koichi Arashima; Kazutosi Nisizawa

1990-01-01

227

Biogeography of Marine Algae  

E-print Network

Biogeography of Marine Algae David J Garbary, St Francis Xavier University, Antigonish, Nova Scotia and vicariance in establishing distributions and as factors associated with speciation. Since eukaryotic algae. There are many species that are virtually cosmopolitan (e.g. the green alga Enteromorpha intestinalis, the red

228

The ultrastructure of the marine blue green alga, Trichodesmium erythraeum , with special reference to the cell wall, gas vacuoles, and cylindrical bodies  

Microsoft Academic Search

The marine blue green alga, Trichodesmium erythraeum, was studied with electron microscopy in an attempt to elucidate the structural basis for its rapid lysis when removed from its marine environment. In this connection, it was found that a thining of the electron-dense layer of the longitudinal wall at the site adjacent to transverse wall attachment was responsible for lysis. The

Chase Baalen; R. Malcolm Brown

1969-01-01

229

Draft Genome Sequence of Vibrio owensii GRA50-12, Isolated from Green Algae in the Intertidal Zone of Eastern Taiwan.  

PubMed

Vibrio owensii GRA50-12 was isolated from symbiotic green algae of coral. The genome contains genes encoding toxin production, virulence regulation, stress response proteins, types II, IV, and VI secretion systems, and proteins for the metabolism of aromatic compounds, which reflects its pathogenic potential and its ecological roles in the ocean. PMID:25593265

Lin, Ling-Chun; Lin, Guang-Huey; Tseng, Yi-Hsiung; Yu, Mei-Shiuan

2015-01-01

230

Draft Genome Sequence of Vibrio owensii GRA50-12, Isolated from Green Algae in the Intertidal Zone of Eastern Taiwan  

PubMed Central

Vibrio owensii GRA50-12 was isolated from symbiotic green algae of coral. The genome contains genes encoding toxin production, virulence regulation, stress response proteins, types II, IV, and VI secretion systems, and proteins for the metabolism of aromatic compounds, which reflects its pathogenic potential and its ecological roles in the ocean. PMID:25593265

Lin, Ling-Chun; Lin, Guang-Huey

2015-01-01

231

What is Ostreococcus tauri? Ostreococcus tauri is a unicellular green algae that was discovered in the Mediterranean Thau lagoon (France) in 1994. With a size less than  

E-print Network

is simple with a relatively large nucleus, a single chloroplast, one mitochondrium, one Golgi body and a very reduced cytoplasmatic compartment. A membrane surrounds the cells, but no cell wall can, compared to other green algae. Apart from this simple cellular structure, the genome size of Ostreococcus

Gent, Universiteit

232

Characterization of the heterotrimeric G-protein complex and its regulator from the green alga Chara braunii expands the evolutionary breadth of plant G-protein signaling.  

PubMed

The lack of heterotrimeric G-protein homologs in the sequenced genomes of green algae has led to the hypothesis that, in plants, this signaling mechanism coevolved with the embryophytic life cycle and the acquisition of terrestrial habitat. Given the large evolutionary gap that exists between the chlorophyte green algae and most basal land plants, the bryophytes, we evaluated the presence of this signaling complex in a charophyte green alga, Chara braunii, proposed to be the closest living relative of land plants. The C. braunii genome encodes for the entire G-protein complex, the G?, G?, and G? subunits, and the REGULATOR OF G-PROTEIN SIGNALING (RGS) protein. The biochemical properties of these proteins and their cross-species functionality show that they are functional homologs of canonical G-proteins. The subunit-specific interactions between CbG? and CbG?, CbG? and CbG?, and CbG? and CbRGS are also conserved, establishing the existence of functional G-protein complex-based signaling mechanisms in green algae. PMID:24179134

Hackenberg, Dieter; Sakayama, Hidetoshi; Nishiyama, Tomoaki; Pandey, Sona

2013-12-01

233

Preliminary laboratory experimentation on the potential of mass-scale cultivation of a high-potein blue-green alga, spirulina geitleri, utilizing cattle feedlot manure  

Microsoft Academic Search

Major detriments to beef production in Hawaii are the cost of feed and the problems associated with the treatment and disposal of the manure in a environmentally safe manner. In an effort to alleviate these problems, laboratory studies were conducted on the feasibility of culturing the high protein (> 50%) blue-green alga Spirulina in elutriated (washed) manure and in the

M. T. Santerre; G. L. Dugan; P. K. Takahashi

1978-01-01

234

Draft Genome Sequence of Pseudomonas pelagia CL-AP6, a Psychrotolerant Bacterium Isolated from Culture of Antarctic Green Alga Pyramimonas gelidicola.  

PubMed

Pseudomonas pelagia CL-AP6, isolated from a culture of the Antarctic green alga Pyramimonas gelidicola, is a psychrotolerant bacterium. Here, we report the draft genome sequence of this strain, which may provide insights into the mutualistic interaction between microalgae and bacteria in sea ice, as well as the cold adaptation mechanisms of bacteria. PMID:24009125

Koh, Hye Yeon; Jung, Woongsic; Do, Hackwon; Lee, Sung Gu; Lee, Jun Hyuck; Kim, Hak Jun

2013-01-01

235

Anti-cancer effects of blue-green alga Spirulina platensis, a natural source of bilirubin-like tetrapyrrolic compounds.  

PubMed

Spirulina platensis is a blue-green alga used as a dietary supplement because of its hypocholesterolemic properties. Among other bioactive substances, it is also rich in tetrapyrrolic compounds closely related to bilirubin molecule, a potent antioxidant and anti-proliferative agent. The aim of our study was to evaluate possible anticancer effects of S. platensis and S. platensis-derived tetrapyrroles using an experimental model of pancreatic cancer. The anti-proliferative effects of S. platensis and its tetrapyrrolic components [phycocyanobilin (PCB) and chlorophyllin, a surrogate molecule for chlorophyll A] were tested on several human pancreatic cancer cell lines and xenotransplanted nude mice. The effects of experimental therapeutics on mitochondrial reactive oxygen species (ROS) production and glutathione redox status were also evaluated. Compared to untreated cells, experimental therapeutics significantly decreased proliferation of human pancreatic cancer cell lines in vitro in a dose-dependent manner (from 0.16 g•L-1 [S. platensis], 60 ?M [PCB], and 125 ?M [chlorophyllin], p<0.05). The anti-proliferative effects of S. platensis were also shown in vivo, where inhibition of pancreatic cancer growth was evidenced since the third day of treatment (p < 0.05). All tested compounds decreased generation of mitochondrial ROS and glutathione redox status (p = 0.0006; 0.016; and 0.006 for S. platensis, PCB, and chlorophyllin, respectively). In conclusion, S. platensis and its tetrapyrrolic components substantially decreased the proliferation of experimental pancreatic cancer. These data support a chemopreventive role of this edible alga. Furthermore, it seems that dietary supplementation with this alga might enhance systemic pool of tetrapyrroles, known to be higher in subjects with Gilbert syndrome. PMID:24552870

Koní?ková, Renata; Va?ková, Kate?ina; Vaníková, Jana; Vá?ová, Kate?ina; Muchová, Lucie; Subhanová, Iva; Zadinová, Marie; Zelenka, Jaroslav; Dvo?ák, Aleš; Kolá?, Michal; Strnad, Hynek; Rimpelová, Silvie; Ruml, Tomáš; J Wong, Ronald; Vítek, Libor

2014-01-01

236

Promotive effect of se on the growth and antioxidation of a blue-green alga Spirulina maxima  

NASA Astrophysics Data System (ADS)

Cultures of a blue-green alga Spirulina maxima (Setch. et Gard.) Geitler with various concentrations of Se in Zarrouk's medium showed that not higher than 40 mg/L Se could promote its growth. The present experiments showed that S. maxima grown under normal conditions, has an oxidant stress defence system for hydrogen peroxide (H2O2) removal, which is the Halliwell-Asada pathway. When 4 to 20 mg/L Se was added to the algal medium, this pathway was replaced by a so-called Sestressed pathway containing GSH peroxidase (GSH-POD). As a result of the occurrence of both higher activity of GSH-POD and lower levels of hydroxyl radical (OH·), the Se-stressed pathway scavenged H2O2 so effectively that the growth of S. maxima was promoted by 4 to 20 mg/L Se. While GSH-POD activity of the alga disappeared at 40 mg/L Se, the recovery of ascorbate peroxidase was observed. The lower levels of ascorbic acid and GSH made the Halliwell-Asada pathway for scavenging H2O2 less effective, while the highest activity of catalase might be responsible in part for the H2O2 removal, causing the level of OH· in S. maxima grown at 40 mg/L Se to be much higher than the OH· level in this alga grown at 4 to 20 mg/L Se, but lower than that in the control. The OH· level changes caused the growth of S. maxima cultured at 40 mg/L Se to increase slightly to close to that of the control.

Zhi-Gang, Zhou; Zhi-Li, Liu

1998-12-01

237

Effect of nutrients on growth and lipid accumulation in the green algae Dunaliella tertiolecta.  

PubMed

Production of biofuel from algae is dependent on the microalgal biomass production rate and lipid content. Both biomass production and lipid accumulation are limited by several factors, of which nutrients play a key role. In this research, the marine microalgae Dunaliella tertiolecta was used as a model organism and a profile of its nutritional requirements was determined. Inorganic phosphate PO4(3-) and trace elements: cobalt (Co2+), iron (Fe3+), molybdenum (Mo2+) and manganese (Mn2+) were identified as required for algae optimum growth. Inorganic nitrogen in the form of nitrate NO3- instead of ammonium (NH4+) was required for maximal biomass production. Lipids accumulated under nitrogen starvation growth condition and this was time-dependent. Results of this research can be applied to maximize production of microalgal lipids in optimally designed photobioreactors. PMID:20947341

Chen, Meng; Tang, Haiying; Ma, Hongzhi; Holland, Thomas C; Ng, K Y Simon; Salley, Steven O

2011-01-01

238

Determination of growth rate depression of some green algae by atrazine  

SciTech Connect

A common contaminant of surface waters of agricultural regions is the triazine herbicide, atrazine (2-chloro-4-ethylamino-6-isoproplyamino-s-triazine). Atrazine effectively inhibits growth and photosynthesis of most plants, including freshwater algae. Both depression of growth rate and reduced yield have been used as parameters in studies of the effects of atrazine on algal growth. Considerable variation exists among algal toxicity methods despite attempts at standardization. Experimental endpoints range from percent inhibitions to EC50s. Algae from two different Iowa springs were the subjects of a study of naturally occurring atrazine tolerance. The authors report here the results of two aspects of that study: development of a quick method of assessing toxin effects on algal growth, and investigation of a ecologically meaningful endpoint for toxin-growth experiments.

Hersh, C.M.; Crumpton, W.G.

1987-12-01

239

Effect of pesticides on blue-green algae and nitrogen-fixation  

Microsoft Academic Search

The effects of the pesticides, amitrol, a derivative of amitrol (viz. 3,5-diamino-1,2,4-triazole), diquat, paraquat, linuron, MCPA, malathion, and monuron, were studied on the nitrogen-fixing algae,Anabaena cylindrica, Aulosira sp.,Calothrix elenkenii, Chlorogloeae fritschii, Cylindrospermum muscicola, Nostoc sp. fromCollema tenax, Nostoc muscorum, Tolypothrix tenuis, andWestiellopsis sp. In general, two types of response were discernible; an initial period of depression succeeded by an increased

Edgar J. DaSilva; Lars Eric Henriksson; Elisabet Henriksson

1975-01-01

240

Effects of temperature on the astaxanthin productivity and light harvesting characteristics of the green alga Haematococcus pluvialis.  

PubMed

The green alga Haematococcus pluvialis, which accumulates astaxanthin at an optimal temperature of 20°C, was cultivated under temperatures of 20°C, 23.5°C, 27°C, and 30.5°C, in order to assess the effects on algal metabolism during the growth phase. The culture growth rate declined with above-optimal increases in temperature, and the final maximum cell concentration at 30.5°C reached only 35% of that attained at 20°C. On the contrary, the biomass productivity was increased under all the high-temperature conditions, probably reflecting the metabolism switch from cell duplication to energy accumulation that is typically observed in algal cultures subjected to environmental stress. Moreover, an increase in the light-harvesting capability of the alga was observed by means of the total pigment balance and the photosynthesis-intensity (PI) curve measured under the different cultivation conditions. Cultures kept at higher temperatures were able to better harvest and utilize the impinging light due to photo-acclimation. Finally, the differences in the astaxanthin metabolism were elucidated by subjecting the cultures to nitrogen starvation at 20°C and 27°C. In the culture at 27°C, a 1.4-fold increase in the astaxanthin productivity was observed when compared to that at 20°C, and the latter required almost two-fold more energy for the astaxanthin production compared with the 27°C culture. PMID:25441445

Giannelli, Luca; Yamada, Hiroyuki; Katsuda, Tomohisa; Yamaji, Hideki

2014-11-01

241

Hydrogen metabolism of green algae: discovery and early research - a tribute to Hans Gaffron and his coworkers.  

PubMed

The detection of hydrogen metabolism in green algae more than 60 years ago by Hans Gaffron dispelled the widely accepted dogma at that time that this feature was unique to prokaryotic organisms. Research on this unexpected aspect of algal physiology has continued until today because of its evolutionary implications and possible practical significance. This minireview focuses on the work of Gaffron and his collaborators, whose experiments provided most of the information about the mechanism of hydrogen metabolism in algae during the 35 years following its discovery. It is shown that the emergence of our present mechanistic concepts was closely linked to the changing perception of the process of photosynthetic water oxidation. Whereas the mechanism of 'photoreduction,' i.e., the photoassimilation of carbon dioxide with hydrogen as the electron donor, was well understood already by Gaffron's group as being a reaction mediated by Photosystem I only, a clear concept of the mechanism of light-dependent hydrogen production has been more difficult to establish. Gaffron and his collaborators provided ample evidence, however, that 'photohydrogen' evolution can be fueled by reducing equivalents derived from a photolysis of water as well as by an oxidation of internal and external organic molecules. The presently prevailing view embraces this concept of multiple pathways, but the relative contribution of each of them, and the regulatory mechanisms determining it, remain a matter of debate. PMID:16228569

Homann, Peter H

2003-01-01

242

A 150 Kilodalton Cell Surface Protein Is Induced by Salt in the Halotolerant Green Alga Dunaliella salina.  

PubMed

Dunaliella salina is an extremely halotolerant, unicellular, green alga lacking a rigid cell wall. Osmotic adaptation to high salinities is based on the accumulation of glycerol. To uncover other functions responsible for halotolerance, protein profiles of algae continuously grown in different salinities were compared. A 150 kilodalton protein (p 150) increased in amount with salt concentration. Furthermore, when the cells were subjected to drastic hyperosmotic shocks, p150 started to rise long after completion of the osmotic response but coincident with reinitiation of cell proliferation. Cells with an initially higher level of p150 resumed growth faster than cells with a lower level of the protein. Addition of cycloheximide early after hyperosmotic shock prevented the rise in p150, indicating this rise was due to de novo synthesis of the protein. These observations suggest that p150 is a saltinduced protein required for proliferation of the cells in saline media. p150 was purified to homogeneity and found to be a detergent-soluble glycoprotein. Polyclonal antibodies against p150 recognized a single protein component in D. salina crude extracts. A high M(r) cross-reacting protein was also observed in another Dunaliella strain, D. bardawil. Immunoelectron microscopy localized p150 to the cell surface. PMID:16668060

Sadka, A; Himmelhoch, S; Zamir, A

1991-03-01

243

A 150 Kilodalton Cell Surface Protein Is Induced by Salt in the Halotolerant Green Alga Dunaliella salina1  

PubMed Central

Dunaliella salina is an extremely halotolerant, unicellular, green alga lacking a rigid cell wall. Osmotic adaptation to high salinities is based on the accumulation of glycerol. To uncover other functions responsible for halotolerance, protein profiles of algae continuously grown in different salinities were compared. A 150 kilodalton protein (p 150) increased in amount with salt concentration. Furthermore, when the cells were subjected to drastic hyperosmotic shocks, p150 started to rise long after completion of the osmotic response but coincident with reinitiation of cell proliferation. Cells with an initially higher level of p150 resumed growth faster than cells with a lower level of the protein. Addition of cycloheximide early after hyperosmotic shock prevented the rise in p150, indicating this rise was due to de novo synthesis of the protein. These observations suggest that p150 is a saltinduced protein required for proliferation of the cells in saline media. p150 was purified to homogeneity and found to be a detergent-soluble glycoprotein. Polyclonal antibodies against p150 recognized a single protein component in D. salina crude extracts. A high Mr cross-reacting protein was also observed in another Dunaliella strain, D. bardawil. Immunoelectron microscopy localized p150 to the cell surface. Images Figure 8 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9 PMID:16668060

Sadka, Avi; Himmelhoch, Stanley; Zamir, Ada

1991-01-01

244

Comparative effects of the blue green algae Nodularia spumigena and a lysed extract on detoxification and antioxidant enzymes in the green lipped mussel (Perna viridis).  

PubMed

Nodularia spumigena periodically proliferates to cause toxic algal blooms with some aquatic animals enduring and consuming high densities of the blue green algae or toxic lysis. N. spumigena contains toxic compounds such as nodularin and lipopolysaccharides. This current work investigates physiological effects of exposure from bloom conditions of N. spumigena cells and a post-bloom lysis. Biochemical and antioxidative biomarkers were comparatively studied over an acute 3-day exposure. In general, a post-bloom N. spumigena lysis caused opposite physiological responses to bloom densities of N. spumigena. Specifically, increases in glutathione (GSH) and glutathione peroxidase (GPx) and decreases in glutathione S-transferase (GST) were observed from the N. spumigena lysis. In contrast, N. spumigena cell densities decreased GSH and increased GST and lipid peroxidation (LPO) in mussels. Findings also suggest that at different stages of a toxic bloom, exposure may result in toxic stress to specific organs in the mussel. PMID:16291202

Davies, Warren R; Siu, William H L; Jack, Ralph W; Wu, Rudolf S S; Lam, Paul K S; Nugegoda, Dayanthi

2005-01-01

245

Anticholinesterase poisonings in dogs from a cyanobacterial (blue-green algae) bloom dominated by Anabaena flos-aquae.  

PubMed

Cyanobacteria (blue-green algae) implicated in the deaths of 9 dogs at Richmond Lake, SD, on Aug 26, 1985, were analyzed. The dominant cyanobacterial species from the water sample was Anabaena flos-aquae. The lyophilized bloom material or the high-performance liquid chromatography purified toxin peak, when administered to mice IP, induced clinical signs of salivation, lacrimation, urinary incontinence, defecation, convulsion, fasciculation, and respiratory arrest. Further comparison of the semipurified bloom toxin with an irreversible anticholinesterase anatoxin-a(s), produced by A flos-aquae strain NRC-525-17, revealed the bloom toxin and anatoxin-a(s) had similar properties on high-performance liquid chromatography and on the inhibition of electric eel acetylcholinesterase (EC 3.1.1.7). PMID:3132068

Mahmood, N A; Carmichael, W W; Pfahler, D

1988-04-01

246

Postmaturational Cleavage of 23s Ribosomal Ribonucleic Acid and Its Metabolic Control in the Blue-Green Alga Anacystis nidulans  

PubMed Central

Data are presented consistent with the notion that the 23s ribosomal ribonucleic acid (rRNA) of Anacystis nidulans undergoes specific endonucleolytic cleavage in vivo, to produce two fragments with molecular weights of 0.88 × 106 and 0.17 × 106 daltons. Cleavage occurred at random after 23s rRNA formation and was stimulated by light in this organism, an obligately photoautotrophic unicellular blue-green alga. The half-life of intact 23s rRNA was about 5 h in illuminated cultures and 10 h in unilluminated cultures. 3-(p-Chlorophenyl)-1, 1-dimethylurea, an inhibitor of photosystem II, retarded 23s rRNA cleavage in the light. The results are discussed in the context of recent reports of rRNA instability in a variety of eukaryotic and prokaryotic organisms. PMID:4632397

Doolittle, W. Ford

1973-01-01

247

Interactive effect of brassinosteroids and cytokinins on growth, chlorophyll, monosaccharide and protein content in the green alga Chlorella vulgaris (Trebouxiophyceae).  

PubMed

Interaction between brassinosteroids (BRs) (brassinolide, BL; 24-epibrassinolide, 24-epiBL; 28-homobrassinolide, 28-homoBL; castasterone, CS; 24-epicastasterone, 24-epiCS; 28-homocastasterone, 28-homoCS) and adenine- (trans-zeatin, tZ; kinetin, Kin) as well as phenylurea-type (1,3-diphenylurea, DPU) cytokinins (CKs) in the regulation of cell number, phytohormone level and the content of chlorophyll, monosaccharide and protein in unicellular green alga Chlorella vulgaris (Trebouxiophyceae) were examined. Chlorella vulgaris exhibited sensitivity to CKs in the following order of their stimulating properties: 10 nM tZ > 100 nM Kin >1 ?M DPU. Exogenously applied BRs possessed the highest biological activity in algal cells at concentration of 10 nM. Among the BRs, BL was characterized by the highest activity, while 28-homoCS - by the lowest. The considerable increase in the level of all endogenous BRs by 27-46% was observed in C. vulgaris culture treated with exogenous 10 nM tZ. It can be speculated that CKs may stimulate BR activity in C. vulgaris by inducing the accumulation of endogenous BRs. CKs interacted synergistically with BRs increasing the number of cells and endogenous accumulation of proteins, chlorophylls and monosaccharides in C. vulgaris. The highest stimulation of algal growth and the contents of analyzed biochemical parameters were observed for BL applied in combination with tZ, whereas the lowest in the culture treated with both 28-homoCS and DPU. However, regardless of the applied mixture of BRs with CKs, the considerable increase in cell number and the metabolite accumulation was found above the level obtained in cultures treated with any single phytohormone in unicellular green alga C. vulgaris. PMID:24787502

Bajguz, Andrzej; Piotrowska-Niczyporuk, Alicja

2014-07-01

248

Pectin Metabolism and Assembly in the Cell Wall of the Charophyte Green Alga Penium margaritaceum1[W][OPEN  

PubMed Central

The pectin polymer homogalacturonan (HG) is a major component of land plant cell walls and is especially abundant in the middle lamella. Current models suggest that HG is deposited into the wall as a highly methylesterified polymer, demethylesterified by pectin methylesterase enzymes and cross-linked by calcium ions to form a gel. However, this idea is based largely on indirect evidence and in vitro studies. We took advantage of the wall architecture of the unicellular alga Penium margaritaceum, which forms an elaborate calcium cross-linked HG-rich lattice on its cell surface, to test this model and other aspects of pectin dynamics. Studies of live cells and microscopic imaging of wall domains confirmed that the degree of methylesterification and sufficient levels of calcium are critical for lattice formation in vivo. Pectinase treatments of live cells and immunological studies suggested the presence of another class of pectin polymer, rhamnogalacturonan I, and indicated its colocalization and structural association with HG. Carbohydrate microarray analysis of the walls of P. margaritaceum, Physcomitrella patens, and Arabidopsis (Arabidopsis thaliana) further suggested the conservation of pectin organization and interpolymer associations in the walls of green plants. The individual constituent HG polymers also have a similar size and branched structure to those of embryophytes. The HG-rich lattice of P. margaritaceum, a member of the charophyte green algae, the immediate ancestors of land plants, was shown to be important for cell adhesion. Therefore, the calcium-HG gel at the cell surface may represent an early evolutionary innovation that paved the way for an adhesive middle lamella in multicellular land plants. PMID:24652345

Domozych, David S.; Sřrensen, Iben; Popper, Zoë A.; Ochs, Julie; Andreas, Amanda; Fangel, Jonatan U.; Pielach, Anna; Sacks, Carly; Brechka, Hannah; Ruisi-Besares, Pia; Willats, William G.T.; Rose, Jocelyn K.C.

2014-01-01

249

Loliolide in marine algae  

Microsoft Academic Search

Loliolide content was determined in 13 marine algae including red, brown and green algae collected from the Black Sea, the Dardanelles and the Aegean Sea. Identification and quantification were performed by gas chromatography-mass spectrometry. The loliolide content in green alga is 1.76 µg g, ranges from 0.14 to 4.35 µg g in red and from 0.18 to 4.83 µg g

Aline Percot; Ahmet Yalç?n; Veysel Aysel; Hüseyin Erdu?an; Berrin Dural; Kas?m Cemal Güven

2009-01-01

250

An update on carotenoid biosynthesis in algae: phylogenetic evidence for the existence of two classes of phytoene synthase.  

PubMed

Carotenoids play crucial roles in structure and function of the photosynthetic apparatus of bacteria, algae, and higher plants. The entry-step reaction to carotenoid biosynthesis is catalyzed by the phytoene synthase (PSY), which is structurally and functionally related in all organisms. A comparative genomic analysis regarding the PSY revealed that the green algae Ostreococcus and Micromonas possess two orthologous copies of the PSY genes, indicating an ancient gene duplication event that produced two classes of PSY in algae. However, some other green algae (Chlamydomonas reinhardtii, Chlorella vulgaris, and Volvox carteri), red algae (Cyanidioschyzon merolae), diatoms (Thalassiosira pseudonana and Phaeodactylum tricornutum), and higher plants retained only one class of the PSY gene whereas the other gene copy was lost in these species. Further, similar to the situation in higher plants recent gene duplications of PSY have occurred for example in the green alga Dunaliella salina/bardawil. As members of the PSY gene families in some higher plants are differentially regulated during development or stress, the discovery of two classes of PSY gene families in some algae suggests that carotenoid biosynthesis in these algae is differentially regulated in response to development and environmental stress as well. PMID:19066941

Tran, Duc; Haven, James; Qiu, Wei-Gang; Polle, Juergen E W

2009-02-01

251

Gas-bacuoles and other viruslike structures in blue-green algae  

Microsoft Academic Search

The result of electron microscopic investigation of gas-vacuoles in a culture of the benthal algaOscillatoria chalybea was compared with the extensive literature concerning gas-vacuole formation and virus infection in bacteria and animals.\\u000a \\u000a On the basis of 21 features indicating that gas-vacuoles are pathological inclusions it was concluded that they are viruslike\\u000a particles.\\u000a \\u000a \\u000a \\u000a Viruslike structures have also been found in our

E. Fjerdingstad

1972-01-01

252

Comparison of plastid 16S rRNA (rrn16) genes from Helicosporidium spp.: evidence supporting the reclassification of Helicosporidia as green algae (Chlorophyta).  

PubMed

The Helicosporidia are invertebrate pathogens that have recently been identified as non-photosynthetic green algae (Chlorophyta). In order to confirm the algal nature of the genus Helicosporidium, the presence of a retained chloroplast genome in Helicosporidia cells was investigated. Fragments homologous to plastid 16S rRNA (rrn16) genes were amplified successfully from cellular DNA extracted from two different Helicosporidium isolates. The fragment sequences are 1269 and 1266 bp long, are very AT-rich (60.7 %) and are similar to homologous genes sequenced from non-photosynthetic green algae. Maximum-parsimony, maximum-likelihood and neighbour-joining methods were used to infer phylogenetic trees from an rrn16 sequence alignment. All trees depicted the Helicosporidia as sister taxa to the non-photosynthetic, pathogenic alga Prototheca zopfii. Moreover, the trees identified Helicosporidium spp. as members of a clade that included the heterotrophic species Prototheca spp. and the mesotrophic species Chlorella protothecoides. The clade is always strongly supported by bootstrap values, suggesting that all these organisms share a most recent common ancestor. Phylogenetic analyses inferred from plastid 16S rRNA genes confirmed that the Helicosporidia are non-photosynthetic green algae, close relatives of the genus Prototheca (Chlorophyta, Trebouxiophyceae). Such phylogenetic affinities suggest that Helicosporidium spp. are likely to possess Prototheca-like organelles and organelle genomes. PMID:14657099

Tartar, Aurélien; Boucias, Drion G; Becnel, James J; Adams, Byron J

2003-11-01

253

Noninvasive measurement of membrane potential modulation in microorganisms: photosynthesis in green algae.  

PubMed

Cell membrane potential (CMP) modulation is a physical measurement to quantitatively probe cell physiology in real time at high specificity. Electrochemical field effect transistors (eFETs) made from graphene and Si nanowire provide strong mechanical and electrical coupling with neurons and muscle cells to noninvasively measure CMP at high sensitivity. To date, there are no noninvasive methods to study electrophysiology of microorganisms because of stiff cell walls and significantly smaller membrane polarizations. An eFET made from the smallest possible nanostructure, a nanoparticle, with sensitivity to a single-electron charge is developed to noninvasively measure CMP modulation in algae. The applicability of the device is demonstrated by measuring CMP modulation due to a light-induced proton gradient inside the chloroplast during photosynthesis. The ?9 mV modulation in CMP in algae is consistent with the absorbance spectrum of chlorophyll, photosynthetic pathway, and inorganic carbon source concentration in the environment. The method can potentially become a routine method to noninvasively study electrophysiology of cells, such as microorganisms for biofuels. PMID:24354302

Lee, Eun-Hee; Lee, Seung-Woo; Saraf, Ravi F

2014-01-28

254

Food production and gas exchange system using blue-green alga (Spirulina) for CELSS  

NASA Astrophysics Data System (ADS)

In order to reduce the cultivation area required for the growth of higher plants in space adoption of algae, which have a higher photosynthetic ability, seems very suitable for obtaining oxygen and food as a useful source of high quality protein. The preliminary cultivation experiment for determining optimum cultivation conditions and for obtaining the critical design parameters of the cultivator itself has been conducted. Spirulina was cultivated in the 6-liter medium containing a sodium hydrogen carbonate solution and a cultivation temperature controlled using a thermostat. Generated oxygen gas was separated using a polypropyrene porous hollow fiber membrane module. Through this experiment, oxygen gas (at a concentration of more than 46%) at a rate of 100 ~ 150 ml per minute could be obtained.

Oguchi, Mitsuo; Otsubo, Koji; Nitta, Keiji; Hatayama, Shigeki

255

Food production and gas exchange system using blue-green alga (spirulina) for CELSS  

NASA Technical Reports Server (NTRS)

In order to reduce the cultivation area required for the growth of higher plants in space adoption of algae, which have a higher photosynthetic ability, seems very suitable for obtaining oxygen and food as a useful source of high quality protein. The preliminary cultivation experiment for determining optimum cultivation conditions and for obtaining the critical design parameters of the cultivator itself was conducted. Spirulina was cultivated in the 6 liter medium containing a sodium hydrogen carbonate solution and a cultivation temperature controlled using a thermostat. Generated oxygen gas was separated using a polypropyrene porous hollow fiber membrane module. Through this experiment, oxygen gas (at a concentration of more than 46 percent) at a rate of 100 to approx. 150 ml per minute could be obtained.

Oguchi, Mitsuo; Otsubo, Koji; Nitta, Keiji; Hatayama, Shigeki

1987-01-01

256

Salicylhydroxamic acid (SHAM) inhibition of the dissolved inorganic carbon concentrating process in unicellular green algae  

SciTech Connect

Rates of photosynthetic O{sub 2} evolution, for measuring K{sub 0.5}(CO{sub 2} + HCO{sub 3}{sup {minus}}) at pH 7, upon addition of 50 micromolar HCO{sub 3}{sup {minus}} to air-adapted Chlamydomonas, Dunaliella, or Scenedesmus cells, were inhibited up to 90% by the addition of 1.5 to 4.0 millimolar salicylhydroxamic acid (SHAM) to the aqueous medium. The apparent K{sub i}(SHAM) for Chlamydomonas cells was about 2.5 millimolar, but due to low solubility in water effective concentrations would be lower. Salicylhydroxamic acid did not inhibit oxygen evolution or accumulation of bicarbonate by Scenedesmus cells between pH 8 to 11 or by isolated intact chloroplasts from Dunaliella. Thus, salicylhydroxamic acid appears to inhibit CO{sub 2} uptake, whereas previous results indicate that vanadate inhibits bicarbonate uptake. These conclusions were confirmed by three test procedures with three air-adapted algae at pH 7. Salicylhydroxamic acid inhibited the cellular accumulation of dissolved inorganic carbon, the rate of photosynthetic O{sub 2} evolution dependent on low levels of dissolved inorganic carbon (50 micromolar NaHCO{sub 3}), and the rate of {sup 14}CO{sub 2} fixation with 100 micromolar ({sup 14}C)HCO{sub 3}{sup {minus}}. Salicylhydroxamic acid inhibition of O{sub 2} evolution and {sup 14}CO{sub 2}-fixation was reversed by higher levels of NaHCO{sub 3}. Thus, salicylhydroxamic acid inhibition was apparently not affecting steps of photosynthesis other than CO{sub 2} accumulation. Although salicylhydroxamic acid is an inhibitor of alternative respiration in algae, it is not known whether the two processes are related.

Goyal, A.; Tolbert, N.E. (Michigan State Univ., East Lansing (USA))

1990-03-01

257

Green energy from marine algae: biogas production and composition from the anaerobic digestion of Irish seaweed species.  

PubMed

Marine algae have emerged as an alternative feedstock for the production of a number of renewable fuels, including biogas. In addition to energy potential, other characteristics make them attractive as an energy source, including their ability to absorb carbon dioxide (CO2), higher productivity rates than land-based crops and the lack of water use or land competition. For Ireland, biofuels from marine algae can play an important role by reducing imports of fossil fuels as well as providing the necessary energy in rural communities. In this study, five potential seaweed species common in Irish waters, Saccorhiza polyschides, Ulva sp., Laminaria digitata, Fucus serratus and Saccharina latissima, were co-digested individually with bovine slurry. Batch reactors of 120ml and 1000ml were set up and incubated at 35 degrees C to investigate their suitability for production of biogas. Digesters fed with S. latissima produced the maximum methane yield (335 ml g volatile solids(-1) (g(VS)(-1) followed by S. polyschides with 255 ml g(VS)(-1). L. digitata produced 246ml g(VS)(-1) and the lowest yields were from the green seaweed Ulva sp. 191ml g(VS)(-1). The methane and CO2 percentages ranged between 50-72% and 10-45%, respectively. The results demonstrated that the seaweed species investigated are good feedstocks candidates for the production of biogas and methane as a source of energy. Their use on a large-scale process will require further investigation to increase yields and reduce production costs. PMID:24350482

Vanegas, C H; Bartlett, J

2013-01-01

258

Molecular and biochemical analysis of the first ARA6 homologue, a RAB5 GTPase, from green algae.  

PubMed

RAB5 GTPases are important regulators of endosomal membrane traffic in yeast, plants, and animals. A specific subgroup of this family, the ARA6 group, has been described in land plants including bryophytes, lycophytes, and flowering plants. Here, we report on the isolation of an ARA6 homologue in a green alga. CaARA6 (CaRABF1) from Chara australis, a member of the Characeae that is a close relative of land plants, encodes a polypeptide of 237 aa with a calculated molecular mass of 25.4 kDa, which is highly similar to ARA6 members from Arabidopsis thaliana and other land plants and has GTPase activity. When expressed in Nicotiana benthamiana leaf epidermal cells, fluorescently tagged CaARA6 labelled organelles with diameters between 0.2 and 1.2 µm, which co-localized with fluorescently tagged AtARA6 known to be present on multivesicular endosomes. Mutations in the membrane-anchoring and GTP-binding sites altered the localization of CaARA6 comparable to that of A. thaliana ARA6 (RABF1). In characean internodal cells, confocal immunofluorescence and immunogold electron microscopy with antibodies against AtARA6 and CaARA6 revealed ARA6 epitopes not only at multivesicular endosomes but also at the plasma membrane, including convoluted domains (charasomes), and at the trans-Golgi network. Our findings demonstrate that ARA6-like proteins have a more ancient origin than previously thought. They indicate further that ARA6-like proteins could have different functions in spite of the high similarity between characean algae and flowering plants. PMID:24127512

Hoepflinger, Marion C; Geretschlaeger, Anja; Sommer, Aniela; Hoeftberger, Margit; Nishiyama, Tomoaki; Sakayama, Hidetoshi; Hammerl, Peter; Tenhaken, Raimund; Ueda, Takashi; Foissner, Ilse

2013-12-01

259

A clade uniting the green algae Mesostigma viride and Chlorokybus atmophyticus represents the deepest branch of the Streptophyta in chloroplast genome-based phylogenies  

PubMed Central

Background The Viridiplantae comprise two major phyla: the Streptophyta, containing the charophycean green algae and all land plants, and the Chlorophyta, containing the remaining green algae. Despite recent progress in unravelling phylogenetic relationships among major green plant lineages, problematic nodes still remain in the green tree of life. One of the major issues concerns the scaly biflagellate Mesostigma viride, which is either regarded as representing the earliest divergence of the Streptophyta or a separate lineage that diverged before the Chlorophyta and Streptophyta. Phylogenies based on chloroplast and mitochondrial genomes support the latter view. Because some green plant lineages are not represented in these phylogenies, sparse taxon sampling has been suspected to yield misleading topologies. Here, we describe the complete chloroplast DNA (cpDNA) sequence of the early-diverging charophycean alga Chlorokybus atmophyticus and present chloroplast genome-based phylogenies with an expanded taxon sampling. Results The 152,254 bp Chlorokybus cpDNA closely resembles its Mesostigma homologue at the gene content and gene order levels. Using various methods of phylogenetic inference, we analyzed amino acid and nucleotide data sets that were derived from 45 protein-coding genes common to the cpDNAs of 37 green algal/land plant taxa and eight non-green algae. Unexpectedly, all best trees recovered a robust clade uniting Chlorokybus and Mesostigma. In protein trees, this clade was sister to all streptophytes and chlorophytes and this placement received moderate support. In contrast, gene trees provided unequivocal support to the notion that the Mesostigma + Chlorokybus clade represents the earliest-diverging branch of the Streptophyta. Independent analyses of structural data (gene content and/or gene order) and of subsets of amino acid data progressively enriched in slow-evolving sites led us to conclude that the latter topology reflects the true organismal relationships. Conclusion In disclosing a sister relationship between the Mesostigmatales and Chlorokybales, our study resolves the long-standing debate about the nature of the unicellular flagellated ancestors of land plants and alters significantly our concepts regarding the evolution of streptophyte algae. Moreover, in predicting a richer chloroplast gene repertoire than previously inferred for the common ancestor of all streptophytes, our study has contributed to a better understanding of chloroplast genome evolution in the Viridiplantae. PMID:17222354

Lemieux, Claude; Otis, Christian; Turmel, Monique

2007-01-01

260

Changes in pigments profile in the green alga Haeamtococcus pluvialis exposed to environmental stresses  

Microsoft Academic Search

Haematococcus green culture starved for either nitrogen or phosphate accumulated astaxanthin up to 4% cell dry wt (2.6 g l-1). While under nitrogen starvation astaxanthin accumulation was faster (maximum achieved after 8 days in comparison to 14 days in the phosphate-starved culture) and accompanied by a drop in the chlorophyll content per cell down to 50% of its original value (30 pg cell-1); in the

Sammy Boussiba; Wang Bing; Jian-Ping Yuan; Aliza Zarka; Feng Chen

1999-01-01

261

Alkaloids in Marine Algae  

PubMed Central

This paper presents the alkaloids found in green, brown and red marine algae. Algal chemistry has interested many researchers in order to develop new drugs, as algae include compounds with functional groups which are characteristic from this particular source. Among these compounds, alkaloids present special interest because of their pharmacological activities. Alkaloid chemistry has been widely studied in terrestrial plants, but the number of studies in algae is insignificant. In this review, a detailed account of macro algae alkaloids with their structure and pharmacological activities is presented. The alkaloids found in marine algae may be divided into three groups: 1. Phenylethylamine alkaloids, 2. Indole and halogenated indole alkaloids, 3. Other alkaloids. PMID:20390105

Güven, Kas?m Cemal; Percot, Aline; Sezik, Ekrem

2010-01-01

262

Bioaccumulation and toxicity of zinc in the green alga, Cladophora glomerata.  

PubMed

The bioaccumulation and toxicity of zinc in Cladophora glomerata from two populations in the River Roding, Essex, UK, were examined in experimental laboratory flowing-water channels. Plants were subjected to zinc concentrations ranging from 0 to 4.0 mg litre(-1) at current velocities of 20-33 cm s(-1) for up to 3 h. Zinc in algal tissue was then quantified and toxicity was assessed by the ability of the alga to grow in a recovery medium after the experimental treatment. There was little difference in zinc bioaccumulation between Cladophora from the site showing mild organic pollution and that from the site subjected to considerable inputs from urban and motorway runoff. Uptake of zinc increased with increasing concentration in the test solution and was linear and proportional up to 0.4 mg litre(-1). Three stages of uptake were identified with the most dramatic accumulation occurring in the first 10 min. Experimental concentration factors ranged from 1.9-5.2 x 10(3), which were in agreement with those previously obtained in the field. Cellular damage was evident in Cladophora subjected to 0.4 mg litre(-1) zinc, and this increased with increasing zinc concentration, thus leading to the conclusion that, at times, the levels of zinc found in the river could be potentially damaging. PMID:15092250

McHardy, B M; George, J J

1990-01-01

263

Flow shear induced cross-stream migration by a green alga  

NASA Astrophysics Data System (ADS)

Swimming and migration characteristics of micro-organisms in shear flows has overarching implications in formation of biological thin layers in aquatic ecosystems, design of bioreactors, and cell separations. Experiments are conducted in a microfluidic channel using digital holographic microscopy. A motile micro-alga, Dunaliella primolecta, is studied in a laminar shear flow at maximum shear rates ranging from 0.1 to 25 s-1. It is found that D. primolecta cells aggregate in the direction of positive vorticity when a critical local shear rate of 5 s-1 is reached. Unlike nonmotile cells, D. primolecta in high shear flow do not rotate along the Jeffrey orbits, neither resumes the local vorticity of flow. The torque on cell body is counter-acted by the spatial alignment of beating flagella. It is speculated that under severe viscous stresses, motile cells "opt" to align themselves in the direction where the least stresses are experienced on cell wall. Beating of flagella, which prevents cells from assuming local flow vorticity, consequently propel them in the span wise direction and allow them to disperse only in a thin two-dimensional layer.

Chengala, Anwar; Hondzo, Miki; Sheng, Jian

2010-11-01

264

On the way to cyanobacterial blooms: Impact of the herbicide metribuzin on the competition between a green alga ( Scenedesmus) and a cyanobacterium ( Microcystis)  

Microsoft Academic Search

The hypothesis that exposure to a common and widely applied photosynthesis-inhibiting herbicide, metribuzin, would alter the outcome of the competitive battle between susceptible green algae (Scenedesmus obliquus) and tolerant cyanobacteria (Microcystis aeruginosa) was tested. In a long-term (17d) experiment, Scenedesmus and Microcystis populations as well as mixtures that started with different inoculum composition (i.e. 3:1, 1:1 and 1:3 Scenedesmus:Microcystis) were

M. F. L. L. W. Lürling; Ivo Roessink

2006-01-01

265

Light-stimulated respiration in the green alga Dunaliella tertiolecta : Involvement of the ultraviolet\\/blue-light photoreceptor(s) and phytochrome?  

Microsoft Academic Search

Starch breakdown and respiratory O2 uptake in the green algaDunaliella tertiolecta (Butcher) are stimulated not only by blue, but also by red light. In the present study, attempts are described to identify the photoreceptor(s) involved. Fluence rate-response curves with different slopes in the ultraviolet (UV)\\/blue and in the red spectral region as well as differences in the kinetics and in

Giinter Ruyters

1988-01-01

266

Experimental substantiation of the possibility of developing selenium- and iodine-containing pharmaceuticals based on blue–green algae Spirulina platensis  

Microsoft Academic Search

The great potential of using blue–green algae Spirulina platensis as a matrix for the production of selenium- and iodine-containing pharmaceuticals is shown experimentally. The background levels of 31 major, minor and trace elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni (using (n,p) reaction), As, Br, Zn, Rb, Mo, Ag, Sb, I, Ba, Sm, Tb,

L. M Mosulishvili; E. I Kirkesali; A. I Belokobylsky; A. I Khizanishvili; M. V Frontasyeva; S. S Pavlov; S. F Gundorina

2002-01-01

267

The effect of different polychlorinated biphenyls on two aquatic models, the green alga Pseudokirchneriella subcapitata and the haemocytes from the European abalone Haliotis tuberculata.  

PubMed

The present study was conducted to determine the toxicity of different polychlorinated biphenyls (PCBs) on the green algae, Pseudokirchneriella subcapitata and the haemocytes from the European abalone, Haliotis tuberculata. Using the algal growth inhibition test, the green algae median Effective Concentration (EC50) values ranged from 0.34?M for PCB28 to more than 100?M for PCBs 101 and 153. Considering the MTT viability test, the abalone EC50 values ranged from 1.67?M for PCB153 to 89?M for PCB28. Our results in contrast to previous observation in vertebrates did not show significant differences between the dioxin like- and non dioxin like-PCBs toxicities regardless of the model used. However, our results demonstrated that the toxicities of PCBs were species dependent. For example, PCB28 was the most toxic compound for P. subcapitata whereas PCBs 1, 180 and 153 were less toxic for that species. On the contrary, PCB153 was reported as the most toxic for H. tuberculata haemocytes and PCB28 the least toxic. To investigate the mode of action of these compounds, we used an in silico method. Our results suggested that PCBs have a non-specific mode of action (e.g., narcosis) on green algae, and another mode of action, probably more specific than narcosis, was reported for PCBs on the abalone haemocytes. PMID:24630249

Halm-Lemeille, Marie-Pierre; Abbaszadeh Fard, Elham; Latire, Thomas; Ferard, Jean-François; Costil, Katherine; Lebel, Jean-Marc; Bureau, Ronan; Serpentini, Antoine

2014-09-01

268

Transcriptional analysis of cell growth and morphogenesis in the unicellular green alga Micrasterias (Streptophyta), with emphasis on the role of expansin  

PubMed Central

Background Streptophyte green algae share several characteristics of cell growth and cell wall formation with their relatives, the embryophytic land plants. The multilobed cell wall of Micrasterias denticulata that rebuilds symmetrically after cell division and consists of pectin and cellulose, makes this unicellular streptophyte alga an interesting model system to study the molecular controls on cell shape and cell wall formation in green plants. Results Genome-wide transcript expression profiling of synchronously growing cells identified 107 genes of which the expression correlated with the growth phase. Four transcripts showed high similarity to expansins that had not been examined previously in green algae. Phylogenetic analysis suggests that these genes are most closely related to the plant EXPANSIN A family, although their domain organization is very divergent. A GFP-tagged version of the expansin-resembling protein MdEXP2 localized to the cell wall and in Golgi-derived vesicles. Overexpression phenotypes ranged from lobe elongation to loss of growth polarity and planarity. These results indicate that MdEXP2 can alter the cell wall structure and, thus, might have a function related to that of land plant expansins during cell morphogenesis. Conclusions Our study demonstrates the potential of M. denticulata as a unicellular model system, in which cell growth mechanisms have been discovered similar to those in land plants. Additionally, evidence is provided that the evolutionary origins of many cell wall components and regulatory genes in embryophytes precede the colonization of land. PMID:21943227

2011-01-01

269

Identification of a gene for UDP-sulfoquinovose synthase of a green alga, Chlamydomonas reinhardtii, and its phylogeny.  

PubMed

Sulfoquinovosyl diacylglycerol is responsible for the structural and functional integrity of the photosystem II complex of a green alga, Chlamydomonas reinhardtii. We cloned a cDNA of C. reinhardtii containing an open reading frame for a protein 36-64% identical in the primary structure to known UDP-sulfoquinovose synthases, which are required for SQDG synthesis, in other organisms. Through the introduction of the cDNA, a cyanobacterial disruptant as to the UDP-sulfoquinovose synthase gene recovered the ability to synthesize sulfoquinovosyl diacylglycerol, thus confirming that the cDNA encodes the UDP-sulfoquinovose synthase. On the genome, the cDNA was divided into 14 exons, and the gene designated as SQD1 was present as one copy. The molecular phylogenetic tree for the UDP-sulfoquinovose synthase showed grouping of C. reinhardtii together with species that require sulfoquinovosyl diacylglycerol for the functioning of the PSII complex, but not with those that do not utilize the lipid for photosynthesis. The role of sulfoquinovosyl diacylglycerol in the functioning of the photosynthetic membranes might evolve in harmony with the system of the membrane lipid synthesis such as UDP-sulfoquinovose synthase gene. PMID:15029954

Sato, Norihiro; Sugimoto, Kouichi; Meguro, Ayano; Tsuzuki, Mikio

2003-12-31

270

Electrochemical Potential Gradients of H+, K+, Ca2+, and Cl- across the Tonoplast of the Green Alga Eremosphaera Viridis.  

PubMed Central

Using ion-selective microelectrodes, we measured the activity of H+, K+, Ca2+, and Cl- and the electrical potential both in the vacuole and in the cytoplasm of the unicellular green alga Eremosphaera viridis to obtain comparable values of the named parameters from the same object under identical conditions. The cytosol had a pH of 7.3, and activities of the other ions were 130 mM K+, 160 nM Ca2+, and 2.2 mM Cl-. We observed only small and transient light-dependent changes of the cytosolic Ca2+ activity. The vacuolar K+ activity did not differ significantly from the cytosolic one. The Ca2+ activity inside the vacuole was approximately 200 [mu]M, the pH was 5.0, and the Cl- activity was 6.2 mM. The concentrations of K+, Ca2+, and Cl- in cell extracts were measured by induction-coupled plasma spectroscopy and anion chromatography. This confirmed the vacuolar activities for K+ and Cl- obtained with ion-selective microelectrodes and indicated that approximately 60% of the vacuolar Ca2+ was buffered. The tonoplast potential was vanishingly low ([less than or equal to][plus or minus]2 mV). There was no detectable electrochemical potential gradient for K+ across the tonoplast, but there was, however, an obvious electrochemical potential gradient for Cl- (-26 mV), indicating an active accumulation of Cl- inside the vacuole. PMID:12228672

Bethmann, B.; Thaler, M.; Simonis, W.; Schonknecht, G.

1995-01-01

271

Elevated water temperature reduces the acute toxicity of the widely used herbicide diuron to a green alga, Pseudokirchneriella subcapitata.  

PubMed

In the actual environment, temperatures fluctuate drastically through season or global warming and are thought to affects risk of pollutants for aquatic biota; however, there is no report about the effect of water temperature on toxicity of widely used herbicide diuron to fresh water microalgae. The present research investigated inhibitory effect of diuron on growth and photosynthetic activity of a green alga Pseudokirchneriella subcapitata at five different temperatures (10, 15, 20, 25, and 30 °C) for 144 h of exposure. As a result, effective diuron concentrations at which a 50% decrease in algal growth occurred was increased with increasing water temperature ranging from 9.2 to 20.1 ?g L(-1) for 72 h and 9.4-28.5 ?g L(-1) for 144 h. The photochemical efficiency of photosystem II (F v/F m ratio) was significantly reduced at all temperatures by diuron exposure at 32 ?g L(-1) after 72 h. Inhibition rates was significantly increased with decreased water temperature (P?

Tasmin, Rumana; Shimasaki, Yohei; Tsuyama, Michito; Qiu, Xuchun; Khalil, Fatma; Okino, Nozomu; Yamada, Naotaka; Fukuda, Shinji; Kang, Ik-Joon; Oshima, Yuji

2014-01-01

272

3-D analysis of dictyosomes and multivesicular bodies in the green alga Micrasterias denticulata by FIB/SEM tomography.  

PubMed

In the present study we employ FIB/SEM tomography for analyzing 3-D architecture of dictyosomes and formation of multivesicular bodies (MVB) in high pressure frozen and cryo-substituted interphase cells of the green algal model system Micrasterias denticulata. The ability of FIB/SEM of milling very thin 'slices' (5-10 nm), viewing the block face and of capturing cytoplasmic volumes of several hundred ?m(3) provides new insight into the close spatial connection of the ER-Golgi machinery in an algal cell particularly in z-direction, complementary to informations obtained by TEM serial sectioning or electron tomography. Our FIB/SEM series and 3-D reconstructions show that interphase dictyosomes of Micrasterias are not only closely associated to an ER system at their cis-side which is common in various plant cells, but are surrounded by a huge "trans-ER" sheath leading to an almost complete enwrapping of dictyosomes by the ER. This is particularly interesting as the presence of a trans-dictyosomal ER system is well known from mammalian secretory cells but not from cells of higher plants to which the alga Micrasterias is closely related. In contrast to findings in plant storage tissue indicating that MVBs originate from the trans-Golgi network or its derivatives our investigations show that MVBs in Micrasterias are in direct spatial contact with both, trans-Golgi cisternae and the trans-ER sheath which provides evidence that both endomembrane compartments are involved in their formation. PMID:24135121

Wanner, Gerhard; Schäfer, Tillman; Lütz-Meindl, Ursula

2013-11-01

273

A freshwater green alga under cadmium stress: ameliorating calcium effects on ultrastructure and photosynthesis in the unicellular model Micrasterias.  

PubMed

Cadmium is a highly toxic heavy metal pollutant arising mainly from increasing industrial disposal of electronic components. Due to its high solubility it easily enters soil and aquatic environments. Via its similarity to calcium it may interfere with different kinds of Ca dependent metabolic or developmental processes in biological systems. In the present study we investigate primary cell physiological, morphological and ultrastructural responses of Cd on the unicellular freshwater green alga Micrasterias which has served as a cell biological model system since many years and has proved to be highly sensitive to any kind of abiotic stress. Our results provide evidence that the severe Cd effects in Micrasterias such as unidirectional disintegration of dictyosomes, occurrence of autophagy, decline in photosystem II activity and oxygen production as well as marked structural damage of the chloroplast are based on a disturbance of Ca homeostasis probably by displacement of Ca by Cd. This is indicated by the fact that physiological and structural cadmium effects could be prevented in Micrasterias by pre-treatment with Ca. Additionally, thapsigargin an inhibitor of animal and plant Ca(2+)-ATPase mimicked the adverse Cd induced morphological and functional effects on dictyosomes. Recovery experiments indicated rapid repair mechanisms after Cd stress. PMID:22762790

Andosch, Ancuela; Affenzeller, Matthias J; Lütz, Cornelius; Lütz-Meindl, Ursula

2012-10-15

274

3-D analysis of dictyosomes and multivesicular bodies in the green alga Micrasterias denticulata by FIB/SEM tomography?  

PubMed Central

In the present study we employ FIB/SEM tomography for analyzing 3-D architecture of dictyosomes and formation of multivesicular bodies (MVB) in high pressure frozen and cryo-substituted interphase cells of the green algal model system Micrasterias denticulata. The ability of FIB/SEM of milling very thin ‘slices’ (5–10 nm), viewing the block face and of capturing cytoplasmic volumes of several hundred ?m3 provides new insight into the close spatial connection of the ER–Golgi machinery in an algal cell particularly in z-direction, complementary to informations obtained by TEM serial sectioning or electron tomography. Our FIB/SEM series and 3-D reconstructions show that interphase dictyosomes of Micrasterias are not only closely associated to an ER system at their cis-side which is common in various plant cells, but are surrounded by a huge “trans-ER” sheath leading to an almost complete enwrapping of dictyosomes by the ER. This is particularly interesting as the presence of a trans-dictyosomal ER system is well known from mammalian secretory cells but not from cells of higher plants to which the alga Micrasterias is closely related. In contrast to findings in plant storage tissue indicating that MVBs originate from the trans-Golgi network or its derivatives our investigations show that MVBs in Micrasterias are in direct spatial contact with both, trans-Golgi cisternae and the trans-ER sheath which provides evidence that both endomembrane compartments are involved in their formation. PMID:24135121

Wanner, Gerhard; Schäfer, Tillman; Lütz-Meindl, Ursula

2013-01-01

275

Quality evaluation of the edible blue-green alga Nostoc flagelliforme using a chlorophyll fluorescence parameter and several biochemical markers.  

PubMed

Nostoc flagelliforme is an edible blue-green alga with herbal and dietary values. Due to the diminishing supply of natural N. flagelliforme and the large investment on the development of its cultivation technology, it is anticipated that artificially cultured N. flagelliforme will soon sustain the market supply. Once this change occurs, the storage-associated quality problem will become the focus of attention for future trade. In this paper, we used a chlorophyll fluorescence parameter, maximum quantum efficiency of Photosystem II (Fv/Fm), and several biomarkers to evaluate the quality of several N. flagelliforme samples. It was found that longer storage times resulted in darker coloured solutions (released pigments) and decreased amounts of chlorophyll a (Chl a) and water-soluble sugars (WSS). Additionally, a higher Fv/Fm value suggests better physiological recovery and quality. In actual application, determination of Fv/Fm would be the first step for evaluating the quality of N. flagelliforme, and the biochemical indexes would serve as good secondary markers. PMID:24054244

Gao, Xiang; Yang, Yiwen; Ai, Yufeng; Luo, Hongyi; Qiu, Baosheng

2014-01-15

276

Co-evolution of mitochondrial tRNA import and codon usage determines translational efficiency in the green alga Chlamydomonas.  

PubMed

Mitochondria from diverse phyla, including protozoa, fungi, higher plants, and humans, import tRNAs from the cytosol in order to ensure proper mitochondrial translation. Despite the broad occurrence of this process, our understanding of tRNA import mechanisms is fragmentary, and crucial questions about their regulation remain unanswered. In the unicellular green alga Chlamydomonas, a precise correlation was found between the mitochondrial codon usage and the nature and amount of imported tRNAs. This led to the hypothesis that tRNA import might be a dynamic process able to adapt to the mitochondrial genome content. By manipulating the Chlamydomonas mitochondrial genome, we introduced point mutations in order to modify its codon usage. We find that the codon usage modification results in reduced levels of mitochondrial translation as well as in subsequent decreased levels and activities of respiratory complexes. These effects are linked to the consequential limitations of the pool of tRNAs in mitochondria. This indicates that tRNA mitochondrial import cannot be rapidly regulated in response to a novel genetic context and thus does not appear to be a dynamic process. It rather suggests that the steady-state levels of imported tRNAs in mitochondria result from a co-evolutive adaptation between the tRNA import mechanism and the requirements of the mitochondrial translation machinery. PMID:23028354

Salinas, Thalia; Duby, Francéline; Larosa, Véronique; Coosemans, Nadine; Bonnefoy, Nathalie; Motte, Patrick; Maréchal-Drouard, Laurence; Remacle, Claire

2012-09-01

277

Toxicant Induced Changes on Delayed Fluorescence Decay Kinetics of Cyanobacteria and Green Algae: A Rapid and Sensitive Biotest  

PubMed Central

Algal tests have developed into routine tools for testing toxicity of pollutants in aquatic environments. Meanwhile, in addition to algal growth rates, an increasing number of fluorescence based methods are used for rapid and sensitive toxicity measures. The present study stresses the suitability of delayed fluorescence (DF) as a promising parameter for biotests. DF is based on the recombination fluorescence at the reaction centre of photosystem II, which is emitted only by photosynthetically active cells. We analyzed the effects of three chemicals (3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 3,5 Dichlorophenol (3,5 DCP) and copper) on the shape of the DF decay kinetics for potential use in phytoplankton toxicity tests. The short incubation tests were done with four phytoplankton species, with special emphasis on the cyanobacterium Microcystis aeruginosa. All species exhibited a high sensitivity to DCMU, but cyanobacteria were more affected by copper and less by 3,5 DCP than the tested green algae. Analyses of changes in the DF decay curve in response to the added chemicals indicated the feasibility of the DF decay approach as a rapid and sensitive testing tool. PMID:23646185

Leunert, Franziska; Grossart, Hans-Peter; Gerhardt, Volkmar; Eckert, Werner

2013-01-01

278

Evaluation of antiangiogenic and antiproliferative potential of the organic extract of green algae chlorella pyrenoidosa  

PubMed Central

Objective: algae isolates obtained from fresh and marine resources could be one of the richest sources of novel bioactive secondary metabolites expected to have pharmaceutical significance for new drug development. This study was conducted to evaluate the antiangiogenic and antiproliferative activity of Chlorella pyrenoidosa in experimental models of angiogenesis and by MTT assay. Materials and Methods: lyophilized extract of C. pyrenoidosa was extracted using dichloromethane/methanol (2:1), concentrated and vacuum evaporated to obtain the dried extract. The crude extract was evaluated in the vascular endothelial growth factor (VEGF)-induced angiogenesis in in ovo chick chorioallantoic membrane assay (CAM) at various concentrations (n = 8) using thalidomide and normal saline as positive and untreated control groups, respectively. The crude extract was also subjected to the antiangiogenic activity in the silver nitrate/potassium nitrate cautery model of corneal neovascularization (CN) in rats where topical bevacizumab was used as a positive control. The vasculature was photographed and blood vessel density was quantified using Aphelion imaging software. The extract was also evaluated for its anti proliferative activity by microculture tetrazolium test (MTT) assay using HeLa cancer cell line (ATCC). Results: VEGF increased the blood vessel density by 220% as compared to normal and thalidomide treatment decreased it to 67.2% in in ovo assay. In the in-vivo CN model, the mean neovascular density in the control group, the C. pyrenoidosa extract and bevacizumab group were found to be 100%, 59.02%, and 32.20%, respectively. The Chlorella pyrenoidosa extract negatively affected the viability of HeLa cells. An IC50 value of the extract was 570 ?g/ml, respectively. Conclusion: a significant antiangiogenic activity was observed against VEGF-induced neovascularization and antiproliferative activity by MTT assay. In this study, it could be attributed that the activity may be due to the presence of secondary metabolites in the C. pyrenoidosa extract. PMID:24347763

Kyadari, Mahender; Fatma, Tasneem; Azad, Rajvardhan; Velpandian, Thirumurthy

2013-01-01

279

Transcriptional and cellular responses of the green alga Chlamydomonas reinhardtii to perfluoroalkyl phosphonic acids.  

PubMed

Perfluoroalkyl phosphonic acids (PFPAs), a new class of perfluoroalkyl substances used primarily in the industrial sector as surfactants, were recently detected in surface water and wastewater treatment plant effluents. Toxicological effects of PFPAs have as yet not been investigated in aquatic organisms. The objective of the present study was to evaluate the effects of perfluorooctylphosphonic acid (C8-PFPA) and perfluorodecylphosphonic acid (C10-PFPA) exposure (31-250?g/L) on Chlamydomonas reinhardtii using genomic (qRT-PCR), biochemical (reactive oxygen species production (ROS) and lipid peroxidation), and physiological (cellular viability) indicators. After 72h of exposure, no differences were observed in cellular viability for any of the two perfluorochemicals. However, increase in ROS concentrations (36% and 25.6% at 125 and 250?g/L, respectively) and lipid peroxidation (35.5% and 35.7% at 125 and 250?g/L, respectively) was observed following exposure to C10-PFPA. C8-PFPA exposure did not impact ROS production and lipid peroxidation in algae. To get insights into the molecular response and modes of action of PFPA toxicity, qRT-PCR-based assays were performed to analyze the transcription of genes related to antioxidant responses including superoxide dismutase (SOD-1), glutathione peroxidase (GPX), catalase (CAT), glutathione S-transferase (GST), and ascorbate peroxidase (APX I). Genomic analyses revealed that the transcription of CAT and APX I was up-regulated for all the C10-PFPA concentrations. In addition, PFPAs were quantified in St. Lawrence River surface water samples and detected at concentrations ranging from 250 to 850pg/L for C8-PFPA and 380 to 650pg/L for C10-PFPA. This study supports the prevalence of PFPAs in the aquatic environment and suggests potential impacts of PFPA exposure on the antioxidant defensive system in C. reinhardtii. PMID:25621396

Sanchez, David; Houde, Magali; Douville, Mélanie; De Silva, Amila O; Spencer, Christine; Verreault, Jonathan

2015-03-01

280

The genome of the diatom Thalassiosira pseudonana: Ecology,evolution, and metabolism  

SciTech Connect

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for {approx}20% of global carbon fixation. We report the 34 Mbp draft nuclear genome of the marine diatom, Thalassiosira pseudonana and its 129 Kbp plastid and 44 Kbp mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, utilization of a range of nitrogenous compounds and a complete urea cycle, all attributes that allow diatoms to prosper in the marine environment. Diatoms are unicellular, photosynthetic, eukaryotic algae found throughout the world's oceans and freshwater systems. They form the base of short, energetically-efficient food webs that support large-scale coastal fisheries. Photosynthesis by marine diatoms generates as much as 40% of the 45-50 billion tonnes of organic carbon produced each year in the sea (1), and their role in global carbon cycling is predicted to be comparable to that of all terrestrial rainforests combined (2, 3). Over geological time, diatoms may have influenced global climate by changing the flux of atmospheric carbon dioxide into the oceans (4). A defining feature of diatoms is their ornately patterned silicified cell wall or frustule, which displays species-specific nano-structures of such fine detail that diatoms have long been used to test the resolution of optical microscopes. Recent attention has focused on biosynthesis of these nano-structures as a paradigm for future silica nanotechnology (5). The long history (over 180 million years) and dominance of diatoms in the oceans is reflected by their contributions to vast deposits of diatomite, most cherts and a significant fraction of current petroleum reserves (6). As photosynthetic heterokonts, diatoms reflect a fundamentally different evolutionary history from the higher plants that dominate photosynthesis on land. Higher plants and green, red and glaucophyte algae are derived from a primary endosymbiotic event in which a non-photosynthetic eukaryote acquired a chloroplast by engulfing (or being invaded by) a prokaryotic cyanobacterium. In contrast, dominant bloom-forming eukaryotic phytoplankton in the ocean, such as diatoms and haptophytes, were derived by secondary endosymbiosis whereby a non-photosynthetic eukaryote acquired a chloroplast by engulfing a photosynthetic eukaryote, probably a red algal endosymbiont (Fig. 1). Each endosymbiotic event led to new combinations of genes derived from the hosts and endosymbionts (7). Prior to this project, relatively few diatom genes had been sequenced, few chromosome numbers were known, and genetic maps did not exist (8). The ecological and evolutionary importance of diatoms motivated our sequencing and analysis of the nuclear, plastid, and mitochondrial genomes of the marine centric diatom Thalassiosira pseudonana.

Ambrust, E.V.; Berges, J.; Bowler, C.; Green, B.; Martinez, D.; Putnam, N.; Zhou, S.; Allen, A.; Apt, K.; Bechner, M.; Brzezinski, M.; Chaal, B.; Chiovitti, A.; Davis, A.; Goodstein, D.; Hadi, M.; Hellsten,U.; Hildebrand, M.; Jenkins, B.; Jurka, J.; Kapitonov, V.; Kroger, N.; Lau, W.; Lane, T.; Larimer, F.; Lippmeier, J.; Lucas, S.; Medina, M.; Montsant, A.; Obornik, M.; Parker, M. Schnitzler; Palenik, B.; Pazour,G.; Richardson, P.; Rynearson, T.; Saito, M.; Schwartz, D.; Thamatrakoln,K.; Valentin, K.; Vardi, A.; Wilkerson, F.; Rokhsar, D.; Vardi, A.; Wilkerson, F.P.; Rokhsar, D.S.

2004-09-01

281

Isolation and characterization of a novel chytrid species (phylum Blastocladiomycota), parasitic on the green alga Haematococcus.  

PubMed

A parasite was found in cultures of the green microalga Haematococcus pluvialis that grew epibiotically on algal cells and caused epidemics resulting in damage to the host cultures. The parasite was isolated into axenic culture on solid and liquid media. It was demonstrated to be the sole causative agent of the epidemics. According to its life cycle and phylogenetic analysis based on 18S ribosomal DNA sequences, the pathogen appears to represent a novel chytrid fungus closely related to the vascular plant pathogen Physoderma (Blastocladiomycota), although it differs from all other known chytrids by its infective stage, a wall-less propagule endowed with amoeboid motion and lacking the group's typical flagellum. PMID:18222678

Hoffman, Yoram; Aflalo, Claude; Zarka, Aliza; Gutman, Jenia; James, Timothy Y; Boussiba, Sammy

2008-01-01

282

De novo transcriptomic analysis of hydrogen production in the green alga Chlamydomonas moewusii through RNA-Seq  

PubMed Central

Background Microalgae can make a significant contribution towards meeting global renewable energy needs in both carbon-based and hydrogen (H2) biofuel. The development of energy-related products from algae could be accelerated with improvements in systems biology tools, and recent advances in sequencing technology provide a platform for enhanced transcriptomic analyses. However, these techniques are still heavily reliant upon available genomic sequence data. Chlamydomonas moewusii is a unicellular green alga capable of evolving molecular H2 under both dark and light anaerobic conditions, and has high hydrogenase activity that can be rapidly induced. However, to date, there is no systematic investigation of transcriptomic profiling during induction of H2 photoproduction in this organism. Results In this work, RNA-Seq was applied to investigate transcriptomic profiles during the dark anaerobic induction of H2 photoproduction. 156 million reads generated from 7 samples were then used for de novo assembly after data trimming. BlastX results against NCBI database and Blast2GO results were used to interpret the functions of the assembled 34,136 contigs, which were then used as the reference contigs for RNA-Seq analysis. Our results indicated that more contigs were differentially expressed during the period of early and higher H2 photoproduction, and fewer contigs were differentially expressed when H2-photoproduction rates decreased. In addition, C. moewusii and C. reinhardtii share core functional pathways, and transcripts for H2 photoproduction and anaerobic metabolite production were identified in both organisms. C. moewusii also possesses similar metabolic flexibility as C. reinhardtii, and the difference between C. moewusii and C. reinhardtii on hydrogenase expression and anaerobic fermentative pathways involved in redox balancing may explain their different profiles of hydrogenase activity and secreted anaerobic metabolites. Conclusions Herein, we have described a workflow using commercial software to analyze RNA-Seq data without reference genome sequence information, which can be applied to other unsequenced microorganisms. This study provided biological insights into the anaerobic fermentation and H2 photoproduction of C. moewusii, and the first transcriptomic RNA-Seq dataset of C. moewusii generated in this study also offer baseline data for further investigation (e.g. regulatory proteins related to fermentative pathway discussed in this study) of this organism as a H2-photoproduction strain. PMID:23971877

2013-01-01

283

Response of benthic algae to environmental gradients in an agriculturally dominated landscape  

USGS Publications Warehouse

Benthic algal communities were assessed in an agriculturally dominated landscape in the Central Columbia Plateau, Washington, to determine which environmental variables best explained species distributions, and whether algae species optima models were useful in predicting specific water-quality parameters. Land uses in the study area included forest, range, urban, and agriculture. Most of the streams in this region can be characterized as open-channel systems influenced by intensive dryland (nonirrigated) and irrigated agriculture. Algal communities in forested streams were dominated by blue-green algae, with communities in urban and range streams dominated by diatoms. The predominance of either blue-greens or diatoms in agricultural streams varied greatly depending on the specific site. Canonical correspondence analysis (CCA) indicated a strong gradient effect of several key environmental variables on benthic algal community composition. Conductivity and % agriculture were the dominant explanatory variables when all sites (n = 24) were included in the CCA; water velocity replaced conductivity when the CCA included only agricultural and urban sites. Other significant explanatory variables included dissolved inorganic nitrogen (DIN), orthophosphate (OP), discharge, and precipitation. Regression and calibration models accurately predicted conductivity based on benthic algal communities, with OP having slightly lower predictability. The model for DIN was poor, and therefore may be less useful in this system. Thirty-four algal taxa were identified as potential indicators of conductivity and nutrient conditions, with most indicators being diatoms except for the blue-greens Anabaena sp. and Lyngbya sp.

Munn, M.D.; Black, R.W.; Gruber, S.J.

2002-01-01

284

[Chloroplast ultrastructure in some diatoms from different classes].  

PubMed

Diatoms significantly differ from other groups of heterokont algae in the diversity of chloroplast forms, their number, and location in a cell and in the structure of pyrenoids. The information on the fine structure of chloroplast is recognized to be important for taxonomic and phylogenetic studies of diatoms. Six species of diatoms belonging to different classes have been examined using transmission electron microscopy. New data on the structure of chloroplast have been obtained and characteristics of pyrenoid ultrastructure of diatoms belonging to different phylogenetic clades have been specified. The results enlarge the data obtained earlier and specify a set of features of chloroplast ultrastructure for different phylogenetic clades of diatoms. PMID:19505053

Bedoshvili, E D; Popkova, T P; Likhoshva?, E V

2009-01-01

285

Natural dissolved organic matter mobilizes Cd but does not affect the Cd uptake by the green algae Pseudokirchneriella subcapitata (Korschikov) in resin buffered solutions.  

PubMed

Natural dissolved organic matter (DOM) can have contrasting effects on metal bioaccumulation in algae because of complexation reactions that reduce free metal ion concentrations and because of DOM adsorption to algal surfaces which promote metal adsorption. This study was set up to reveal the role of different natural DOM samples on cadmium (Cd) uptake by the green algae Pseudokirchneriella subcapitata (Korschikov). Six different DOM samples were collected from natural freshwater systems and isolated by reverse osmosis. In addition, one (13)C enriched DOM sample was isolated from soil to trace DOM adsorption to algae. Algae were exposed to standardized solutions with or without these DOM samples, each exposed at equal DOM concentrations and at equal non-toxic Cd(2+) activity (?4 nM) that was buffered with a resin. The DOM increased total dissolved Cd by factors 3-16 due to complexation reactions at equal Cd(2+) activity. In contrast, the Cd uptake was unaffected by DOM or increased maximally 1.6 fold ((13)C enriched DOM). The (13)C analysis revealed that maximally 6% of algal C was derived from DOM and that this can explain the small increase in biomass Cd. It is concluded that free Cd(2+) and not DOM-complexed Cd is the main bioavailable form of Cd when solution Cd(2+) is well buffered. PMID:24874007

Verheyen, Liesbeth; Versieren, Liske; Smolders, Erik

2014-09-01

286

Phytohormones as regulators of heavy metal biosorption and toxicity in green alga Chlorella vulgaris (Chlorophyceae).  

PubMed

The present study was undertaken to test the influence of exogenously applied phytohormones: auxins (IAA, IBA, NAA, PAA), cytokinins (BA, CPPU, DPU, 2iP, Kin, TDZ, Z), gibberellin (GA(3)), jasmonic acid (JA) as well as polyamine - spermidine (Spd) upon the growth and metabolism of green microalga Chlorella vulgaris (Chlorophyceae) exposed to heavy metal (Cd, Cu, Pb) stress. The inhibitory effect of heavy metals on algal growth, metabolite accumulation and enzymatic as well as non-enzymatic antioxidant system was arranged in the following order: Cd > Pb > Cu. Exogenously applied phytohormones modify the phytotoxicity of heavy metals. Auxins, cytokinins, gibberellin and spermidine (Spd) can alleviate stress symptoms by inhibiting heavy metal biosorption, restoring algal growth and primary metabolite level. Moreover, these phytohormones and polyamine stimulate antioxidant enzymes' (superoxide dismutase, ascorbate peroxidase, catalase) activities and ascorbate as well as glutathione accumulation by producing increased antioxidant capacity in cells growing under abiotic stress. Increased activity of antioxidant enzymes reduced oxidative stress expressed by lipid peroxidation and hydrogen peroxide level. In contrast JA enhanced heavy metal toxicity leading to increase in metal biosorption and ROS generation. The decrease in cell number, chlorophylls, carotenoids, monosaccharides, soluble proteins, ascorbate and glutathione content as well as antioxidant enzyme activity was also obtained in response to JA and heavy metals. Determining the stress markers (lipid peroxidation, hydrogen peroxide) and antioxidants' level as well as antioxidant enzyme activity in cells is important for understanding the metal-specific mechanisms of toxicity and that these associated novel endpoints may be useful metrics for accurately predicting toxicity. The data suggest that phytohormones and polyamine play an important role in the C. vulgaris responding to abiotic stressor and algal adaptation ability to metal contamination of aquatic environment. PMID:22305067

Piotrowska-Niczyporuk, Alicja; Bajguz, Andrzej; Zambrzycka, El?bieta; Godlewska-?y?kiewicz, Beata

2012-03-01

287

Salinicoccus qingdaonensis sp. nov., isolated from coastal seawater during a bloom of green algae.  

PubMed

A novel Gram-stain-positive, white-pigmented, non-motile, non-sporulating, catalase- and oxidase-positive, strictly aerobic coccus, designated strain ZXM223(T), was isolated from a seawater sample collected from the coast of Qingdao, PR China, during a green algal bloom. It grew at pH 6.0-10.5 and 0-25.0% (w/v) NaCl, with optimum growth at pH 8.5 and 3.0% (w/v) NaCl. Growth occurred at 16-42 °C (optimum at 28 °C). The major fatty acids were anteiso-C(15:0) and iso-C(15:0). Menaquinone 6 (MK-6) was the major respiratory quinone. The polar lipids were phosphatidylglycerol, three unidentified phospholipids and two unknown glycolipids. The peptidoglycan type was L-Lys-Gly(5-6.) The genomic DNA G+C content was 43.5 mol%. Phylogenetic analysis of the 16S rRNA gene sequence placed strain ZXM223(T) within the genus Salinicoccus, with sequence similarity of 92.2-97.1% between ZXM223(T) and the type strains of this genus. The closest relatives were Salinicoccus kunmingensis YIM Y15(T), 'S. salitudinis' YIM-C678 and S. alkaliphilus T8(T). The DNA-DNA relatedness between strain ZXM223(T) and S. kunmingensis CGMCC 1.6302(T) and 'S. salitudinis' CGMCC 1.6299 (=YIM-C678) was 37±3 and 30±2%, respectively. The phenotypic, chemotaxonomic and phylogenetic characteristics and low DNA-DNA relatedness support the proposal of a novel species of the genus Salinicoccus, Salinicoccus qingdaonensis sp. nov., with the type strain ZXM223(T) (=LMG 24855(T) =CGMCC 1.8895(T)). PMID:21498663

Qu, Zhe; Li, Zhao; Zhang, Xiuming; Zhang, Xiao-Hua

2012-03-01

288

Comparison of Cd(II), Cu(II), and Pb(II) biouptake by green algae in the presence of humic acid.  

PubMed

The present study examines the role of humic acid, as a representative of dissolved organic matter, in Cd(II), Cu(II), and Pb(II) speciation and biouptake by green microalgae. Cellular and intracellular metal fractions were compared in the presence of citric and humic acids. The results demonstrated that Cd and Cu uptake in the presence of 10 mg L(-1) humic acid was consistent with that predicted from measured free metal concentrations, while Pb biouptake was higher. By comparing Cd, Cu, and Pb cellular concentrations in the absence and presence of humic acid, it was found that the influence of the increased negative algal surface charge, resulting from humic acid adsorption, on cellular metal was negligible. Moreover, the experimental results for all three metals were in good agreement with the ternary complex hypothesis. Given that metal has much higher affinity with algal sites than humic acid adsorbed to algae, the contribution of the ternary complex to metal bioavailability was negligible in the case of Cd (II) and Cu (II). In contrast, the ternary complex contributed to over 90% of total cellular metal for Pb(II), due to the comparable affinity of Pb to algal sites in comparison with humic acid adsorbed to algae. Therefore, the extension of the biotic ligand model by including the formation of the ternary complex between the metal, humic acid, and algal surface would help to avoid underestimation of Pb biouptake in the presence of humic substances by green algae Chlorella kesslerii. PMID:17612207

Lamelas, Cristina; Slaveykova, Vera I

2007-06-01

289

Evaluation of an oil-producing green alga Chlorella sp. C2 for biological DeNOx of industrial flue gases.  

PubMed

NOx, a significant portion of fossil fuel flue gases, are among the most serious environmental issues in the world and must be removed in an additional costly gas treatment step. This study evaluated the growth of the green alga Chlorella sp. C2 under a nitrite-simulated NOx environment and the removal rates of actual flue gas fixed salts (FGFSs) from Sinopec's Shijiazhuang refinery along with lipid production. The results showed that nitrite levels lower than 176.5 mM had no significant adverse effects on the cell growth and photosynthesis of Chlorella sp. C2, demonstrating that this green alga could utilize nitrite and NOx as a nitrogen source. High concentrations of nitrite (88.25-176.5 mM) also resulted in the accumulation of neutral lipids. A 60% nitrite removal efficiency was obtained together with the production of 33% algae lipids when cultured with FGFS. Notably, the presence of nitrate in the FGFS medium significantly enhanced the nitrite removal capability, biomass and lipid production. Thus, this study may provide a new insight into the economically viable application of microalgae in the synergistic combination of biological DeNOx of industrial flue gases and biodiesel production. PMID:25105531

Zhang, Xin; Chen, Hui; Chen, Weixian; Qiao, Yaqin; He, Chenliu; Wang, Qiang

2014-09-01

290

Colony organization in the green alga Botryococcus braunii (Race B) is specified by a complex extracellular matrix.  

PubMed

Botryococcus braunii is a colonial green alga whose cells associate via a complex extracellular matrix (ECM) and produce prodigious amounts of liquid hydrocarbons that can be readily converted into conventional combustion engine fuels. We used quick-freeze deep-etch electron microscopy and biochemical/histochemical analysis to elucidate many new features of B. braunii cell/colony organization and composition. Intracellular lipid bodies associate with the chloroplast and endoplasmic reticulum (ER) but show no evidence of being secreted. The ER displays striking fenestrations and forms a continuous subcortical system in direct contact with the cell membrane. The ECM has three distinct components. (i) Each cell is surrounded by a fibrous ?-1, 4- and/or ?-1, 3-glucan-containing cell wall. (ii) The intracolonial ECM space is filled with a cross-linked hydrocarbon network permeated with liquid hydrocarbons. (iii) Colonies are enclosed in a retaining wall festooned with a fibrillar sheath dominated by arabinose-galactose polysaccharides, which sequesters ECM liquid hydrocarbons. Each cell apex associates with the retaining wall and contributes to its synthesis. Retaining-wall domains also form "drapes" between cells, with some folding in on themselves and penetrating the hydrocarbon interior of a mother colony, partitioning it into daughter colonies. We propose that retaining-wall components are synthesized in the apical Golgi apparatus, delivered to apical ER fenestrations, and assembled on the surfaces of apical cell walls, where a proteinaceous granular layer apparently participates in fibril morphogenesis. We further propose that hydrocarbons are produced by the nonapical ER, directly delivered to the contiguous cell membrane, and pass across the nonapical cell wall into the hydrocarbon-based ECM. PMID:22941913

Weiss, Taylor L; Roth, Robyn; Goodson, Carrie; Vitha, Stanislav; Black, Ian; Azadi, Parastoo; Rusch, Jannette; Holzenburg, Andreas; Devarenne, Timothy P; Goodenough, Ursula

2012-12-01

291

Partial purification and characterization of a Ca(2+)-dependent protein kinase from the green alga, Dunaliella salina  

NASA Technical Reports Server (NTRS)

A calcium-dependent protein kinase was partially purified and characterized from the green alga Dunaliella salina. The enzyme was activated at free Ca2+ concentrations above 10(-7) molar. and half-maximal activation was at about 3 x 10(-7) molar. The optimum pH for its Ca(2+)-dependent activity was 7.5. The addition of various phospholipids and diolein had no effects on enzyme activity and did not alter the sensitivity of the enzyme toward Ca2+. The enzyme was inhibited by calmodulin antagonists, N-(6-aminohexyl)-1-naphthalene sulfonamide and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide in a dose-dependent manner while the protein kinase C inhibitor, sphingosine, had little effect on enzyme activity up to 800 micromolar. Immunoassay showed some calmodulin was present in the kinase preparations. However, it is unlikely the kinase was calmodulin regulated, since it still showed stimulation by Ca2+ in gel assays after being electrophoretically separated from calmodulin by two different methods. This gel method of detection of the enzyme indicated that a protein band with an apparent molecular weight of 40,000 showed protein kinase activity at each one of the several steps in the purification procedure. Gel assay analysis also showed that after native gel isoelectric focusing the partially purified kinase preparations had two bands with calcium-dependent activity, at isoelectric points 6.7 and 7.1. By molecular weight, by isoelectric point, and by a comparative immunoassay, the Dunaliella kinase appears to differ from at least some of the calcium-dependent, but calmodulin and phospholipid independent kinases described from higher plants.

Roux, S. J.

1990-01-01

292

Photosynthetic activity and protein overexpression found in Cr(III)-tolerant cells of the green algae Dictyosphaerium chlorelloides.  

PubMed

Chromium is an important constituent in effluents obtained from chromium plating industries. Due to the highly toxic nature of Cr(VI), attention has been shifted to less hazardous Cr(III) electroplating processes. This study evaluated aquatic toxicity of Cr(III)-containing laboratory samples representative of effluents from chromium electroplating industries, on the photosynthetic activity exhibited by both Cr(III)-sensitive (Dc1M(wt)) and tolerant (Dc1M(Cr(III)R30)) Dictyosphaerium chlorelloides strains. Additionally, selected de novo-determined peptide sequences, obtained from Dc1M(Cr(III)R30), have been analyzed to evidence the possible Cr(III) toxic mechanism involved in the resistance of these cells to high Cr(III) levels in aquatic environments. Dc1M(Cr(III)R30) strain exhibited a gross photosynthetic balance of about five times lower than that exhibited by Dc1M(wt) strain, demonstrating that Dc1M(Cr(III)R30) has a photosynthetic yield significantly lower than Dc1M(wt). SDS-PAGE of Dc1M(Cr(III)R30) samples showed the presence of at least two protein bands (23.05 and 153.46 KDa, respectively) absent in wild-type strain samples. Although it has achieved a low coincidence between the lower molecular weight band and a GTPase identified from genome of the green alga Chlamydomonas reinhardtii, none of de novo peptide sequences obtained showed a significant MS-BLAST score, so that further studies will be required. PMID:24556547

Pereira, M; Bartolomé, C M; Sánchez-Fortún, S

2014-08-01

293

Life cycle energy and greenhouse gas emissions for an ethanol production process based on blue-green algae.  

PubMed

Ethanol can be produced via an intracellular photosynthetic process in cyanobacteria (blue-green algae), excreted through the cell walls, collected from closed photobioreactors as a dilute ethanol-in-water solution, and purified to fuel grade ethanol. This sequence forms the basis for a biofuel production process that is currently being examined for its commercial potential. In this paper, we calculate the life cycle energy and greenhouse gas emissions for three different system scenarios for this proposed ethanol production process, using process simulations and thermodynamic calculations. The energy required for ethanol separation increases rapidly for low initial concentrations of ethanol, and, unlike other biofuel systems, there is little waste biomass available to provide process heat and electricity to offset those energy requirements. The ethanol purification process is a major consumer of energy and a significant contributor to the carbon footprint. With a lead scenario based on a natural-gas-fueled combined heat and power system to provide process electricity and extra heat and conservative assumptions around the ethanol separation process, the net life cycle energy consumption, excluding photosynthesis, ranges from 0.55 MJ/MJ(EtOH) down to 0.20 MJ/ MJ(EtOH), and the net life cycle greenhouse gas emissions range from 29.8 g CO?e/MJ(EtOH) down to 12.3 g CO?e/MJ(EtOH) for initial ethanol concentrations from 0.5 wt % to 5 wt %. In comparison to gasoline, these predicted values represent 67% and 87% reductions in the carbon footprint for this ethanol fuel on a energy equivalent basis. Energy consumption and greenhouse gas emissions can be further reduced via employment of higher efficiency heat exchangers in ethanol purification and/ or with use of solar thermal for some of the process heat. PMID:20968295

Luo, Dexin; Hu, Zushou; Choi, Dong Gu; Thomas, Valerie M; Realff, Matthew J; Chance, Ronald R

2010-11-15

294

Model based analysis of transient fluorescence yield induced by actinic laser flashes in spinach leaves and cells of green alga Chlorella pyrenoidosa Chick.  

PubMed

Measurements of Single Flash Induced Transient Fluorescence Yield (SFITFY) on spinach leaves and whole cells of green thermophilic alga Chlorella pyrenoidosa Chick were analyzed for electron transfer (ET) steps and coupled proton transfer (PT) on both the donor and the acceptor side of the reaction center (RC) of photosystem II (PS II). A specially developed PS II model (Belyaeva et al., 2008, 2011a) allowed the determination of ET steps that occur in a hierarchically ordered time scale from nanoseconds to several seconds. Our study demonstrates that our SFITFY data is consistent with the concept of the reduction of P680(+) by YZ in both leaves and algae (studied on spinach leaves and cells of Chlorella pyrenoidosa Chick). The multiphasic P680(+) reduction kinetics by YZ in PS II core complexes with high oxygen evolution capacity was seen in both algae and leaves. Model simulation to fit SFITFY curves for dark adapted species used here gives the rate constants to verify nanosecond kinetic stages of P680(+) reduction by YZ in the redox state S1 of the water oxidizing complex (WOC) shown in Kühn et al. (2004). Then a sequence of relaxation steps in the redox state S1, outlined by Renger (2012), occurs in both algae and leaves as a similar non-adiabatic ET reactions. Coupled PT is discussed briefly to understand a rearrangement of hydrogen bond protons in the protein matrix of the WOC (Umena et al., 2011). On the other hand, present studies showed a slower reoxidation of reduced QA by QB in algal cells as compared with that in a leaf that might be regarded as a consequence of differences of spatial domains at the QB-site in leaves compared to algae. Our comparative study helped to correlate theory with experimental data for molecular photosynthetic mechanisms in thylakoid membranes. PMID:24556534

Belyaeva, N E; Schmitt, F-J; Paschenko, V Z; Riznichenko, G Yu; Rubin, A B; Renger, G

2014-04-01

295

Spectrometric constraint in analysis of benthic diatom biomass using monospecific cultures  

Microsoft Academic Search

Among microphytobenthic species (unicellular algae and cyanobacteria), benthic diatoms are often the most common photosynthetic organisms colonizing shallow marine environment such as an intertidal flat. As such areas, particularly mudflats of limited access for point sampling, remote sensing techniques have the potential to map diatom biomass. This study used two monospecific cultures of the benthic diatoms Navicula ramosissima and Entomoneis

V. Méléder; L. Barillé; P. Launeau; V. Carrčre; Y. Rincé

2003-01-01

296

Accumulation of 241Am by suspended matter, diatoms and aquatic weeds of the Yenisei River  

Microsoft Academic Search

In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating 241Am from water. In our experiments large particles of seston (>8?m), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella

T. A. Zotina; A. Ya. Bolsunovsky; L. G. Bondareva

2010-01-01

297

Synergistic effect of auxins and brassinosteroids on the growth and regulation of metabolite content in the green alga Chlorella vulgaris (Trebouxiophyceae).  

PubMed

The relationships between brassinosteroids (BRs) (brassinolide, BL; 24-epiBL; 28-homoBL; castasterone, CS; 24-epiCS; 28-homoCS) and auxins (indole-3-acetic acid, IAA; indole-3-butyric acid, IBA; indole-3-propionic acid, IPA) in the regulation of cell number, phytohormone level and metabolism in green alga Chlorella vulgaris were investigated. Exogenously applied auxins had the highest biological activity in algal cells at 50 ?M. Among the auxins, IAA was characterized by the highest activity, while IBA - by the lowest. BRs at 0.01 ?M were characterized by the highest biological activity in relation to auxin-treated and untreated cultures of C. vulgaris. The application of 50 ?M IAA stimulated the level of all detected endogenous BRs in C. vulgaris cells. The stimulatory effect of BRs in green algae was arranged in the following order: BL > 24-epiBL > 28-homoBL > CS > 24-epiCS > 28-homoCS. Auxins cooperated synergistically with BRs stimulating algal cell proliferation and endogenous accumulation of proteins, chlorophylls and monosaccharides in C. vulgaris. The highest stimulation of algal growth and the contents of analyzed biochemical parameters were observed for the mixture of BL with IAA, whereas the lowest in the culture treated with both 28-homoCS and IBA. However, regardless of the applied mixture of BRs with auxins, the considerable increase in cell number and the metabolite accumulation was found above the level obtained in cultures treated with any single phytohormone. Obtained results confirm that both groups of plant hormones cooperate synergistically in the control of growth and metabolism of unicellular green alga C. vulgaris. PMID:23994360

Bajguz, Andrzej; Piotrowska-Niczyporuk, Alicja

2013-10-01

298

Antioxidant and free radical scavenging properties of marennine, a blue-green polyphenolic pigment from the diatom Haslea ostrearia (Gaillon/Bory) Simonsen responsible for the natural greening of cultured oysters.  

PubMed

Among microalgae, the marine diatom Haslea ostrearia has the distinctive feature of synthesizing and releasing, into the surrounding environment, a blue-green polyphenolic pigment called marennine. The oyster-breeding industry commonly makes use of this natural phenomenon for the greening of oysters grown in the ponds of the French Atlantic coast. This article reports the in vitro antioxidant properties of pure marennine. Two kinds of evaluation systems were adopted to test the antioxidative activity of marennine: antioxidant capacity assays (beta-carotene and thymidine protection assays and iron reducing power assay) and free radical scavenging assays (DPPH*, O2*-, and HO*). In almost all cases, marennine exhibited significantly higher antioxidative and free radical scavenging activities than natural and synthetic antioxidants commonly used in food, as shown by comparing median effective concentration (EC 50) values, for each test independently. This medium molecular weight polyphenol (around 10 kDa) from microalgae is thus a potentially useful natural antioxidant. Because of its blue-coloring property and water solubility, it could also be used as a natural food-coloring additive. PMID:18636683

Pouvreau, Jean-Bernard; Morançais, Michčle; Taran, Frédéric; Rosa, Philippe; Dufossé, Laurent; Guérard, Fabienne; Pin, Serge; Fleurence, Joël; Pondaven, Pierre

2008-08-13

299

J. Phycol. 39, 259267 (2003) THE MESOZOIC RADIATION OF EUKARYOTIC ALGAE  

E-print Network

259 J. Phycol. 39, 259­267 (2003) MINIREVIEW THE MESOZOIC RADIATION OF EUKARYOTIC ALGAE, and heterokonts (including diatoms, brown algae, and raphidophytes). In Paleozoic and earlier eras, the fossil

Falkowski, Paul G.

300

BOTANICAL BRIEFING Streptophyte algae and the origin of embryophytes  

E-print Network

BOTANICAL BRIEFING Streptophyte algae and the origin of embryophytes Burkhard Becker* and Birger March 2009 Background Land plants (embryophytes) evolved from streptophyte green algae, a small group of freshwater algae ranging from scaly, unicellular flagellates (Mesostigma) to complex, filamentous thalli

301

Blue-green algae  

MedlinePLUS

... a source of dietary protein, B-vitamins, and iron. They are also used for weight loss, attention ... a source of dietary protein, vitamin B12, and iron. Other conditions. More evidence is needed to rate ...

302

Acidophilic green alga Pseudochlorella sp. YKT1 accumulates high amount of lipid droplets under a nitrogen-depleted condition at a low-pH.  

PubMed

Microalgal storage lipids are considered to be a promising source for next-generation biofuel feedstock. However, microalgal biodiesel is not yet economically feasible due to the high cost of production. One of the reasons for this is that the use of a low-cost open pond system is currently limited because of the unavoidable contamination with undesirable organisms. Extremophiles have an advantage in culturing in an open pond system because they grow in extreme environments toxic to other organisms. In this study, we isolated the acidophilic green alga Pseudochlorella sp. YKT1 from sulfuric acid mine drainage in Nagano Prefecture, Japan. The vegetative cells of YKT1 display the morphological characteristics of Trebouxiophyceae and molecular phylogenetic analyses indicated it to be most closely related to Pseudochlorella pringsheimii. The optimal pH and temperature for the growth of YKT1 are pH 3.0-5.0 and a temperature 20-25°C, respectively. Further, YKT1 is able to grow at pH 2.0 and at 32°C, which corresponds to the usual water temperature in the outdoors in summer in many countries. YKT1 accumulates a large amount of storage lipids (?30% of dry weigh) under a nitrogen-depleted condition at low-pH (pH 3.0). These results show that acidophilic green algae will be useful for industrial applications by acidic open culture systems. PMID:25221913

Hirooka, Shunsuke; Higuchi, Sumio; Uzuka, Akihiro; Nozaki, Hisayoshi; Miyagishima, Shin-ya

2014-01-01

303

Acidophilic Green Alga Pseudochlorella sp. YKT1 Accumulates High Amount of Lipid Droplets under a Nitrogen-Depleted Condition at a Low-pH  

PubMed Central

Microalgal storage lipids are considered to be a promising source for next-generation biofuel feedstock. However, microalgal biodiesel is not yet economically feasible due to the high cost of production. One of the reasons for this is that the use of a low-cost open pond system is currently limited because of the unavoidable contamination with undesirable organisms. Extremophiles have an advantage in culturing in an open pond system because they grow in extreme environments toxic to other organisms. In this study, we isolated the acidophilic green alga Pseudochlorella sp. YKT1 from sulfuric acid mine drainage in Nagano Prefecture, Japan. The vegetative cells of YKT1 display the morphological characteristics of Trebouxiophyceae and molecular phylogenetic analyses indicated it to be most closely related to Pseudochlorella pringsheimii. The optimal pH and temperature for the growth of YKT1 are pH 3.0–5.0 and a temperature 20–25°C, respectively. Further, YKT1 is able to grow at pH 2.0 and at 32°C, which corresponds to the usual water temperature in the outdoors in summer in many countries. YKT1 accumulates a large amount of storage lipids (?30% of dry weigh) under a nitrogen-depleted condition at low-pH (pH 3.0). These results show that acidophilic green algae will be useful for industrial applications by acidic open culture systems. PMID:25221913

Hirooka, Shunsuke; Higuchi, Sumio; Uzuka, Akihiro; Nozaki, Hisayoshi; Miyagishima, Shin-ya

2014-01-01

304

Target of Rapamycin and LST8 Proteins Associate with Membranes from the Endoplasmic Reticulum in the Unicellular Green Alga Chlamydomonas reinhardtii?  

PubMed Central

The highly conserved target of rapamycin (TOR) kinase is a central controller of cell growth in all eukaryotes. TOR exists in two functionally and structurally distinct complexes, termed TOR complex 1 (TORC1) and TORC2. LST8 is a TOR-interacting protein that is present in both TORC1 and TORC2. Here we report the identification and characterization of TOR and LST8 in large protein complexes in the model photosynthetic green alga Chlamydomonas reinhardtii. We demonstrate that Chlamydomonas LST8 is part of a rapamycin-sensitive TOR complex in this green alga. Biochemical fractionation and indirect immunofluorescence microscopy studies indicate that TOR and LST8 exist in high-molecular-mass complexes that associate with microsomal membranes and are particularly abundant in the peri-basal body region in Chlamydomonas cells. A Saccharomyces cerevisiae complementation assay demonstrates that Chlamydomonas LST8 is able to functionally and structurally replace endogenous yeast LST8 and allows us to propose that binding of LST8 to TOR is essential for cell growth. PMID:18039939

Díaz-Troya, Sandra; Florencio, Francisco J.; Crespo, José L.

2008-01-01

305

Diatoms in space: testing prospects for reliable diatom nanotechnology in microgravity  

NASA Astrophysics Data System (ADS)

The worldwide effort to grow nanotechnology, rather than use lithography, focuses on diatoms, single cell eukaryotic algae with ornate silica shells, which can be replaced by oxides and ceramics, or reduced to elemental silicon, to create complex nanostructures with compositions of industrial and electronics importance. Diatoms produce an enormous variety of structures, some of which are microtubule dependent and perhaps sensitive to microgravity. The NASA Single Loop for Cell Culture (SLCC) for culturing and observing microorganisms permits inexpensive, low labor in-space experiments. We propose to send up to the International Space Station diatom cultures of the three diatom species whose genomes are currently being sequenced, plus the giant diatoms of Antarctica (up to 6 mm length for a single cell) and the unique colonial diatom, Bacillaria paradoxa. Bacillaria cells move against each other in partial synchrony, like a sliding deck of cards, by a microfluidics mechanism. Will normal diatoms have aberrant patterns, shapes or motility compared to ground controls? The generation time is typically one day, so that many generations may be examined from one flight. Rapid, directed evolution may be possible running the SLCC as a compustat. The shell shapes and patterns are preserved in hard silica, so that the progress of normal and aberrant morphogenesis may be followed by drying samples on a moving filter paper "diatom tape recorder". With a biodiversity of 100,000 distinct species, diatom nanotechnology may offer a compact and portable nanotechnology toolkit for space exploration anywhere.

Gordon, Richard; Hoover, Richard B.; Tuszynski, Jack A.; de Luis, Javier; Camp, Philip J.; Tiffany, Mary Ann; Nagy, Stephen S.; Fayek, Mostafa; Lopez, Pascal J.; Lerner, Beatriz E.

2007-09-01

306

Phycoerythrin and photosynthesis of the pelagic blue-green alga Trichodesmium thiebautii in the waters of Kuroshio, Japan  

Microsoft Academic Search

The photosynthetic function of phycoerythrin was investigated in the alga Trichodesmium thiebautii from the waters of Kuroshio, Japan. The spectroscopic characteristics of the in vivo and isolated T. thiebautii phycoerythrin pigments are identical, and have 3 absorption bands at 495, 547 and 562 nm. Light at the wavelengths corresponding to each absorption band of phycoerythrin is equally efficient in T.

S. Shimura; Y. Fujita

1975-01-01

307

How 5000 independent rowers coordinate their strokes in order to row into the sunlight: Phototaxis in the multicellular green alga Volvox  

PubMed Central

Background The evolution of multicellular motile organisms from unicellular ancestors required the utilization of previously evolved tactic behavior in a multicellular context. Volvocine green algae are uniquely suited for studying tactic responses during the transition to multicellularity because they range in complexity from unicellular to multicellular genera. Phototactic responses are essential for these flagellates because they need to orientate themselves to receive sufficient light for photosynthesis, but how does a multicellular organism accomplish phototaxis without any known direct communication among cells? Several aspects of the photoresponse have previously been analyzed in volvocine algae, particularly in the unicellular alga Chlamydomonas. Results In this study, the phototactic behavior in the spheroidal, multicellular volvocine green alga Volvox rousseletii (Volvocales, Chlorophyta) was analyzed. In response to light stimuli, not only did the flagella waveform and beat frequency change, but the effective stroke was reversed. Moreover, there was a photoresponse gradient from the anterior to the posterior pole of the spheroid, and only cells of the anterior hemisphere showed an effective response. The latter caused a reverse of the fluid flow that was confined to the anterior hemisphere. The responsiveness to light is consistent with an anterior-to-posterior size gradient of eyespots. At the posterior pole, the eyespots are tiny or absent, making the corresponding cells appear to be blind. Pulsed light stimulation of an immobilized spheroid was used to simulate the light fluctuation experienced by a rotating spheroid during phototaxis. The results demonstrated that in free-swimming spheroids, only those cells of the anterior hemisphere that face toward the light source reverse the beating direction in the presence of illumination; this behavior results in phototactic turning. Moreover, positive phototaxis is facilitated by gravitational forces. Under our conditions, V. rousseletii spheroids showed no negative phototaxis. Conclusions On the basis of our results, we developed a mechanistic model that predicts the phototactic behavior in V. rousseletii. The model involves photoresponses, periodically changing light conditions, morphological polarity, rotation of the spheroid, two modes of flagellar beating, and the impact of gravity. Our results also indicate how recently evolved multicellular organisms adapted the phototactic capabilities of their unicellular ancestors to multicellular life. PMID:20663212

2010-01-01

308

Characterization of the Heterotrimeric G-Protein Complex and Its Regulator from the Green Alga Chara braunii Expands the Evolutionary Breadth of Plant G-Protein Signaling1[C][W][OPEN  

PubMed Central

The lack of heterotrimeric G-protein homologs in the sequenced genomes of green algae has led to the hypothesis that, in plants, this signaling mechanism coevolved with the embryophytic life cycle and the acquisition of terrestrial habitat. Given the large evolutionary gap that exists between the chlorophyte green algae and most basal land plants, the bryophytes, we evaluated the presence of this signaling complex in a charophyte green alga, Chara braunii, proposed to be the closest living relative of land plants. The C. braunii genome encodes for the entire G-protein complex, the G?, G?, and G? subunits, and the REGULATOR OF G-PROTEIN SIGNALING (RGS) protein. The biochemical properties of these proteins and their cross-species functionality show that they are functional homologs of canonical G-proteins. The subunit-specific interactions between CbG? and CbG?, CbG? and CbG?, and CbG? and CbRGS are also conserved, establishing the existence of functional G-protein complex-based signaling mechanisms in green algae. PMID:24179134

Hackenberg, Dieter; Sakayama, Hidetoshi; Nishiyama, Tomoaki; Pandey, Sona

2013-01-01

309

Development of a Nuclear Transformation System for Oleaginous Green Alga Lobosphaera (Parietochloris) incisa and Genetic Complementation of a Mutant Strain, Deficient in Arachidonic Acid Biosynthesis  

PubMed Central

Microalgae are considered a promising source for various high value products, such as carotenoids, ?-3 and ?-6 polyunsaturated fatty acids (PUFA). The unicellular green alga Lobosphaera (Parietochloris) incisa is an outstanding candidate for the efficient phototrophic production of arachidonic acid (AA), an essential ?-6 PUFA for infant brain development and a widely used ingredient in the baby formula industry. Although phototrophic production of such algal products has not yet been established, estimated costs are considered to be 2–5 times higher than competing heterotrophic production costs. This alga accumulates unprecedented amounts of AA within triacylglycerols and the molecular pathway of AA biosynthesis in L. incisa has been previously elucidated. Thus, progress in transformation and metabolic engineering of this high value alga could be exploited for increasing the efficient production of AA at competitive prices. We describe here the first successful transformation of L. incisa using the ble gene as a selection marker, under the control of the endogenous RBCS promoter. Furthermore, we have succeeded in the functional complementation of the L. incisa mutant strain P127, containing a mutated, inactive version of the delta-5 (?5) fatty acid desaturase gene. A copy of the functional ?5 desaturase gene, linked to the ble selection marker, was transformed into the P127 mutant. The resulting transformants selected for zeocine resistant, had AA biosynthesis partially restored, indicating the functional complementation of the mutant strain with the wild-type gene. The results of this study present a platform for the successful genetic engineering of L. incisa and its long-chain PUFA metabolism. PMID:25133787

Khozin-Goldberg, Inna; Leu, Stefan; Shapira, Michal; Kaye, Yuval; Tourasse, Nicolas; Vallon, Olivier; Boussiba, Sammy

2014-01-01

310

Genetic engineering of the green alga Chlorella zofingiensis: a modified norflurazon-resistant phytoene desaturase gene as a dominant selectable marker.  

PubMed

The unicellular green alga Chlorella zofingiensis has been proposed as a promising producer of natural astaxanthin, a commercially important ketocarotenoid. But the genetic toolbox for this alga is not available. In the present study, an efficient transformation system was established for C. zofingiensis. The transformation system utilized a modified norflurazon-resistant phytoene desaturase (PDS-L516F, with an leucine-phenylalanine change at position 516) as the selectable marker. Three promoters from endogenous PDS, nitrate reductase (NIT), and ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RBCS) genes were tested, with the RBCS promoter demonstrating the highest transformation efficiency. Inclusion of the first intron of the PDS gene further enhanced the efficiency by 91 %. Both particle bombardment and electroporation methods were examined, and the latter gave a fourfold higher transformation efficiency. The introduction of PDS-L516F, which exhibited a 33 % higher desaturation activity than the unaltered enzyme, enabled C. zofingiensis to produce 32.1 % more total carotenoids (TCs) and 54.1 % more astaxanthin. The enhanced accumulation of astaxanthin in transformants was revealed to be related to the increase in the transcripts of PDS, ?-carotenoid ketolase (BKT), and hydroxylase (CHYb) genes. Our study clearly shows that the modified PDS gene is a dominant selectable marker for the transformation of C. zofingiensis and possibly for the genetic engineering of the carotenoid biosynthetic pathway. In addition, the engineered C. zofingiensis might serve as an improved source of natural astaxanthin. PMID:24584513

Liu, Jin; Sun, Zheng; Gerken, Henri; Huang, Junchao; Jiang, Yue; Chen, Feng

2014-06-01

311

Does the abundance of girellids and kyphosids correlate with cover of the palatable green algae, Ulva spp.? A test on temperate rocky intertidal reefs.  

PubMed

This study assessed whether the abundance of girellids and kyphosids was related to cover of the palatable green algae, Ulva australis and Ulva compressa, on rocky intertidal reefs in Jervis Bay, New South Wales, Australia. No relationship was found between Ulva spp. cover and abundance of Girella tricuspidata, Girella elevata and Kyphosus sydneyanus during a period of relatively low Ulva spp. cover (i.e. February 2011 to March 2011), but during a period of significantly higher Ulva spp. cover (i.e. October 2011 to November 2011) there was a strong correlation between Ulva spp. cover and G. tricuspidata abundance. Spatial analysis indicated that the abundance of G. tricuspidata was consistent across time, suggesting G. tricuspidata were not moving between reefs in response to variation in Ulva spp. cover between periods but rather that large schools of G. tricuspidata resided on reefs that had relatively higher Ulva spp. cover at certain times of the year. PMID:25557432

Ferguson, A M; Harvey, E S; Rees, M J; Knott, N A

2015-01-01

312

On the way to cyanobacterial blooms: impact of the herbicide metribuzin on the competition between a green alga (Scenedesmus) and a cyanobacterium (Microcystis).  

PubMed

The hypothesis that exposure to a common and widely applied photosynthesis-inhibiting herbicide, metribuzin, would alter the outcome of the competitive battle between susceptible green algae (Scenedesmus obliquus) and tolerant cyanobacteria (Microcystis aeruginosa) was tested. In a long-term (17 d) experiment, Scenedesmus and Microcystis populations as well as mixtures that started with different inoculum composition (i.e. 3:1, 1:1 and 1:3 Scenedesmus:Microcystis) were grown in the absence or presence of metribuzin (100 microg l-1). In the absence of metribuzin, Scenedesmus was competitively superior and out-competed Microcystis regardless the initial composition of the mixed communities. However, this competitive outcome was reversed completely in the presence of metribuzin, where despite growth inhibition Microcystis became dominant. Hence, photosynthesis-inhibiting herbicides may not only affect algal community structure, but also provide cyanobacteria founder populations a window for dominance and thus play an important role in promoting cyanobacteria blooms. PMID:16540149

Lürling, Miquel; Roessink, Ivo

2006-10-01

313

Effect of growth temperature on lipid and fatty acid compositions in the blue-green algae, Anabaena variabilis and Anacystis nidulans.  

PubMed

The lipid composition was affected by growth temperature in Anacystis nidulans, but was not in Anabaena variabilis. A. variabilis contained fatty acids of 18 and 16 carbon atoms, which were localized at 1- and 2-positions, respectively, of the glycerol moiety of lipids. Desaturation of C18 acids was affected by the growth temperature. A. nidulans contained fatty acids of 14, 16 and 18 carbon atoms. Monounsaturated and saturated acids were esterified mainly to 1- and 2-position, respectively. Desaturation and chain length of fatty acids were influenced by the growth temperature. The variations in lipid and fatty acid compositions with the growth temperature are discussed in relation to the growth temperature-dependent shift of thermotropic phase transition temperature of the membrane lipids in the blue-green algae. PMID:104734

Sato, N; Murata, N; Miura, Y; Ueta, N

1979-01-29

314

Purity of Chloroplasts Prepared from the Siphonous Green Alga, Caulerpa simpliciuscula, as Determined by Their Ultrastructure and Their Enzymic Content 1  

PubMed Central

The ultrastructure and enzyme distribution in chloroplasts and other subcellular fractions isolated from the siphonous green alga, Caulerpa simpliciuscula, are described. The isolated chloroplasts were similar in appearance to those in the tissue from which they were derived, and in typical preparations 70% or more were intact. Chloroplasts which had lost their outer envelopes could be separated from intact plastids by centrifugation at low speeds through gradients of colloidal silica. Intact chloroplasts separated in this way retained their photosynthetic capacity and were impermeable to ferricyanide ions. The chloroplast preparations separated by differential centrifugation and refractionated using either discontinuous or continuous Percoll gradients contained non-chloroplast material. It was estimated that this amounted to a maximum of 10% of the mitochondrial population and 6% of cytoplasm extracted from the plant. The contaminating material surrounded the chloroplasts in a thin layer and was surrounded by a membrane. Images PMID:16661374

Grant, Bruce R.; Wright, Simon W.

1980-01-01

315

Experimental Substantiation of the Possibility of Developing Selenium- and Iodine-Containing Pharmaceuticals Based on Blue-Green Algae Spirulina Platensis  

E-print Network

The great potential of using blue-green algae Spirulina platensis as a matrix for the production of selenium- and iodine-containing pharmaceuticals is shown experimentally. The background levels of 31 major, minor and trace elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni (using -reaction), As, Br, Zn, Rb, Mo, Ag, Sb, I, Ba, Sm, Tb, Tm, Hf, Ta, W, Au, Hg, Th) in Spirulina platensis biomass were determined by means of epithermal neutron activation analysis. The dependence of selenium and iodine accumulation in spirulina biomass on a nutrient medium loding of the above elements was characterised. To demonstrate the possibilities of determining toxic element intake by spirulina biomass, mercury was selected. The technological parameters for production of iodinated treatment-and-prophylactic pills are developed.

Mosulishvili, L M; Belokobylsky, A I; Khisanishvili, L A; Frontasyeva, M V; Pavlov, C C; Gundorina, S F

2001-01-01

316

RNA-Mediated Silencing in Algae: Biological Roles and Tools for Analysis of Gene Function ?  

PubMed Central

Algae are a large group of aquatic, typically photosynthetic, eukaryotes that include species from very diverse phylogenetic lineages, from those similar to land plants to those related to protist parasites. The recent sequencing of several algal genomes has provided insights into the great complexity of these organisms. Genomic information has also emphasized our lack of knowledge of the functions of many predicted genes, as well as the gene regulatory mechanisms in algae. Core components of the machinery for RNA-mediated silencing show widespread distribution among algal lineages, but they also seem to have been lost entirely from several species with relatively small nuclear genomes. Complex sets of endogenous small RNAs, including candidate microRNAs and small interfering RNAs, have now been identified by high-throughput sequencing in green, red, and brown algae. However, the natural roles of RNA-mediated silencing in algal biology remain poorly understood. Limited evidence suggests that small RNAs may function, in different algae, in defense mechanisms against transposon mobilization, in responses to nutrient deprivation and, possibly, in the regulation of recently evolved developmental processes. From a practical perspective, RNA interference (RNAi) is becoming a promising tool for assessing gene function by sequence-specific knockdown. Transient gene silencing, triggered with exogenously synthesized nucleic acids, and/or stable gene repression, involving genome-integrated transgenes, have been achieved in green algae, diatoms, yellow-green algae, and euglenoids. The development of RNAi technology in conjunction with system level “omics” approaches may provide the tools needed to advance our understanding of algal physiological and metabolic processes. PMID:21803865

Cerutti, Heriberto; Ma, Xinrong; Msanne, Joseph; Repas, Timothy

2011-01-01

317

Isolation and characterization of a PSI-LHCI super-complex and its sub-complexes from a siphonaceous marine green alga, Bryopsis Corticulans.  

PubMed

A novel super-complex of photosystem I (PSI)-light-harvesting complex I (LHCI) was isolated from a siphonaceous marine green alga, Bryopsis corticulans. The super-complex contained 9-10 Lhca antennas as external LHCI bound to the core complex. The super-complex was further disintegrated into PSI core and LHCI sub-complexes, and analysis of the pigment compositions by high-performance liquid chromatography revealed unique characteristics of the B. corticulans PSI in that one PSI core contained around 14 ?-carotenes and 1-2 ?-carotenes. This is in sharp contrast to the PSI core from higher plants and most cyanobacteria where only ?-carotenes were present, and is the first report for an ?-carotene-type PSI core complex among photosynthetic eukaryotes, suggesting a structural flexibility of the PSI core. Lhca antennas from B. corticulans contained seven kinds of carotenoids (siphonaxanthin, all-trans neoxanthin, 9'-cis neoxanthin, violaxanthin, siphonein, ?-carotene, and ?-carotene) and showed a high carotenoid:chlorophyll ratio of around 7.5:13. PSI-LHCI super-complex and PSI core showed fluorescence emission peaks at 716 and 718 nm at 77 K, respectively; whereas two Lhca oligomers had fluorescence peaks at 681 and 684 nm, respectively. By comparison with spinach PSI preparations, it was found that B. corticulans PSI had less red chlorophylls, most of them are present in the core complex but not in the outer light-harvesting systems. These characteristics may contribute to the fine tuning of the energy transfer network, and to acclimate to the ever-changing light conditions under which the unique green alga inhabits. PMID:25214185

Qin, Xiaochun; Wang, Wenda; Chang, Lijing; Chen, Jinghua; Wang, Peng; Zhang, Jianping; He, Yikun; Kuang, Tingyun; Shen, Jian-Ren

2015-01-01

318

Comparative Analysis of the Chemical Composition of Mixed and Pure Cultures of Green Algae and Their Decomposed Residues by 13C Nuclear Magnetic Resonance Spectroscopy  

PubMed Central

It is known that macromolecular organic matter in aquatic environments, i.e., humic substances, is highly aliphatic. These aliphatic macromolecules, predominantly paraffinic in structure, are prevalent in marine and lacustrine sediments and are believed to originate from algae or bacteria. A comparative study of mixed and pure cultures of green algae and their decomposed residues was performed by using solid-state 13C nuclear magnetic resonance spectroscopy as the primary analytical method. Results obtained in this study confirm the presence of components that are chemically refractory and that are defined as alghumin and hydrolyzed alghumin. These were detected in heterogeneous, homogeneous, and axenic biomasses composed of several genera of Chlorophyta. Although the chemical composition of algal biomass varied with culture conditions, the chemical structure of the alghumin and hydrolyzed alghumin, demonstrated by 13C nuclear magnetic resonance spectroscopy appeared to be constant for members of the Chlorophyta examined in this study. The alghumin was dominated by carbohydrate-carbon, with minor amounts of amide or carboxyl carbon and paraffinic carbon, the latter surviving strong hydrolysis by 6 N HCI (hydrolyzed alghumin). Bacterial decomposition of heterogeneous algal biomass labeled with 13C was conducted under both aerobic and anaerobic conditions to determine chemical structure and stability of the refractory material. The refractory fraction ranged from 33% in aerobic to 44% in anaerobic cultures. The refractory fraction recovered from either aerobic or anaerobic degradation comprised 40% alghumin, which represented an enrichment by 10% relative to the proportion of alghumin derived from whole cells of algae. The paraffinic component in the hydrolyzed alghumin of whole algal cells was found to be 1.8% and increased to 5.1 and 6.9% after aerobic and anaerobic bacterial degradation, respectively. It is concluded that members of the Chlorophyta contain a common insoluble structure composed of paraffinic carbon that is resistant to chemical and bacterial degradation under conditions used in this study. The paraffinic structure is identical to those constituting humin of aquatic origin. Thus, alga-derived macromolecular compounds deposited in aquatic environments (alghumin) probably contribute to sedimentary humic substances. PMID:16347601

Zelibor, J. L.; Romankiw, L.; Hatcher, P. G.; Colwell, R. R.

1988-01-01

319

Comparative analysis of the chemical composition of mixed and pure cultures of green algae and their decomposed residues by C nuclear magnetic resonance spectroscopy.  

PubMed

It is known that macromolecular organic matter in aquatic environments, i.e., humic substances, is highly aliphatic. These aliphatic macromolecules, predominantly paraffinic in structure, are prevalent in marine and lacustrine sediments and are believed to originate from algae or bacteria. A comparative study of mixed and pure cultures of green algae and their decomposed residues was performed by using solid-state C nuclear magnetic resonance spectroscopy as the primary analytical method. Results obtained in this study confirm the presence of components that are chemically refractory and that are defined as alghumin and hydrolyzed alghumin. These were detected in heterogeneous, homogeneous, and axenic biomasses composed of several genera of Chlorophyta. Although the chemical composition of algal biomass varied with culture conditions, the chemical structure of the alghumin and hydrolyzed alghumin, demonstrated by C nuclear magnetic resonance spectroscopy appeared to be constant for members of the Chlorophyta examined in this study. The alghumin was dominated by carbohydrate-carbon, with minor amounts of amide or carboxyl carbon and paraffinic carbon, the latter surviving strong hydrolysis by 6 N HCI (hydrolyzed alghumin). Bacterial decomposition of heterogeneous algal biomass labeled with C was conducted under both aerobic and anaerobic conditions to determine chemical structure and stability of the refractory material. The refractory fraction ranged from 33% in aerobic to 44% in anaerobic cultures. The refractory fraction recovered from either aerobic or anaerobic degradation comprised 40% alghumin, which represented an enrichment by 10% relative to the proportion of alghumin derived from whole cells of algae. The paraffinic component in the hydrolyzed alghumin of whole algal cells was found to be 1.8% and increased to 5.1 and 6.9% after aerobic and anaerobic bacterial degradation, respectively. It is concluded that members of the Chlorophyta contain a common insoluble structure composed of paraffinic carbon that is resistant to chemical and bacterial degradation under conditions used in this study. The paraffinic structure is identical to those constituting humin of aquatic origin. Thus, alga-derived macromolecular compounds deposited in aquatic environments (alghumin) probably contribute to sedimentary humic substances. PMID:16347601

Zelibor, J L; Romankiw, L; Hatcher, P G; Colwell, R R

1988-04-01

320

The complete chloroplast DNA sequences of the charophycean green algae Staurastrum and Zygnema reveal that the chloroplast genome underwent extensive changes during the evolution of the Zygnematales  

PubMed Central

Background The Streptophyta comprise all land plants and six monophyletic groups of charophycean green algae. Phylogenetic analyses of four genes from three cellular compartments support the following branching order for these algal lineages: Mesostigmatales, Chlorokybales, Klebsormidiales, Zygnematales, Coleochaetales and Charales, with the last lineage being sister to land plants. Comparative analyses of the Mesostigma viride (Mesostigmatales) and land plant chloroplast genome sequences revealed that this genome experienced many gene losses, intron insertions and gene rearrangements during the evolution of charophyceans. On the other hand, the chloroplast genome of Chaetosphaeridium globosum (Coleochaetales) is highly similar to its land plant counterparts in terms of gene content, intron composition and gene order, indicating that most of the features characteristic of land plant chloroplast DNA (cpDNA) were acquired from charophycean green algae. To gain further insight into when the highly conservative pattern displayed by land plant cpDNAs originated in the Streptophyta, we have determined the cpDNA sequences of the distantly related zygnematalean algae Staurastrum punctulatum and Zygnema circumcarinatum. Results The 157,089 bp Staurastrum and 165,372 bp Zygnema cpDNAs encode 121 and 125 genes, respectively. Although both cpDNAs lack an rRNA-encoding inverted repeat (IR), they are substantially larger than Chaetosphaeridium and land plant cpDNAs. This increased size is explained by the expansion of intergenic spacers and introns. The Staurastrum and Zygnema genomes differ extensively from one another and from their streptophyte counterparts at the level of gene order, with the Staurastrum genome more closely resembling its land plant counterparts than does Zygnema cpDNA. Many intergenic regions in Zygnema cpDNA harbor tandem repeats. The introns in both Staurastrum (8 introns) and Zygnema (13 introns) cpDNAs represent subsets of those found in land plant cpDNAs. They represent 16 distinct insertion sites, only five of which are shared by the two zygnematalean genomes. Three of these insertions sites have not been identified in Chaetosphaeridium cpDNA. Conclusion The chloroplast genome experienced substantial changes in overall structure, gene order, and intron content during the evolution of the Zygnematales. Most of the features considered earlier as typical of land plant cpDNAs probably originated before the emergence of the Zygnematales and Coleochaetales. PMID:16236178

Turmel, Monique; Otis, Christian; Lemieux, Claude

2005-01-01

321

The Central Carbon and Energy Metabolism of Marine Diatoms  

PubMed Central

Diatoms are heterokont algae derived from a secondary symbiotic event in which a eukaryotic host cell acquired an eukaryotic red alga as plastid. The multiple endosymbiosis and horizontal gene transfer processes provide diatoms unusual opportunities for gene mixing to establish distinctive biosynthetic pathways and metabolic control structures. Diatoms are also known to have significant impact on global ecosystems as one of the most dominant phytoplankton species in the contemporary ocean. As such their metabolism and growth regulating factors have been of particular interest for many years. The publication of the genomic sequences of two independent species of diatoms and the advent of an enhanced experimental toolbox for molecular biological investigations have afforded far greater opportunities than were previously apparent for these species and re-invigorated studies regarding the central carbon metabolism of diatoms. In this review we discuss distinctive features of the central carbon metabolism of diatoms and its response to forthcoming environmental changes and recent advances facilitating the possibility of industrial use of diatoms for oil production. Although the operation and importance of several key pathways of diatom metabolism have already been demonstrated and determined, we will also highlight other potentially important pathways wherein this has yet to be achieved. PMID:24957995

Obata, Toshihiro; Fernie, Alisdair R.; Nunes-Nesi, Adriano

2013-01-01

322

Effectiveness of algae in the treatment of a wood-based pulp and paper industry wastewater.  

PubMed

In this study, the ability of algae to treat a wood-based pulp and paper industry wastewater was investigated. Tests were performed in batch reactors seeded with a mixed culture of algae. Under different lighting and initial wastewater strength conditions, changes in COD, AOX and color contents of reactors were followed with time. Algae were found to remove up to 58% of COD, 84% of color and 80% of AOX from pulp and paper industry wastewaters. No remarkable differences were observed in COD and color when light intensity and wastewater strength were changed, while AOX removals were strongly affected. Algal species identification studies revealed that some green algae (Chlorella) and diatom species were dominant in the treatment. The study also showed that algae grew mixotrophically, while the main mechanism of color and organics removal from pulping effluents was partly metabolism and partly metabolic conversion of colored and chlorinated molecules to non-colored and non-chlorinated molecules. Adsorption onto algal biomass was not so effective. PMID:12137261

Tarlan, Esra; Dilek, Filiz B; Yetis, Ulku

2002-08-01

323

Proteome turnover in the green alga Ostreococcus tauri by time course 15N metabolic labeling mass spectrometry.  

PubMed

Protein synthesis and degradation determine the cellular levels of proteins, and their control hence enables organisms to respond to environmental change. Experimentally, these are little known proteome parameters; however, recently, SILAC-based mass spectrometry studies have begun to quantify turnover in the proteomes of cell lines, yeast, and animals. Here, we present a proteome-scale method to quantify turnover and calculate synthesis and degradation rate constants of individual proteins in autotrophic organisms such as algae and plants. The workflow is based on the automated analysis of partial stable isotope incorporation with (15)N. We applied it in a study of the unicellular pico-alga Ostreococcus tauri and observed high relative turnover in chloroplast-encoded ATPases (0.42-0.58% h(-1)), core photosystem II proteins (0.34-0.51% h(-1)), and RbcL (0.47% h(-1)), while nuclear-encoded RbcS2 is more stable (0.23% h(-1)). Mitochondrial targeted ATPases (0.14-0.16% h(-1)), photosystem antennae (0.09-0.14% h(-1)), and histones (0.07-0.1% h(-1)) were comparatively stable. The calculation of degradation and synthesis rate constants k(deg) and k(syn) confirms RbcL as the bulk contributor to overall protein turnover. This study performed over 144 h of incorporation reveals dynamics of protein complex subunits as well as isoforms targeted to different organelles. PMID:22077659

Martin, Sarah F; Munagapati, Vijaya S; Salvo-Chirnside, Eliane; Kerr, Lorraine E; Le Bihan, Thierry

2012-01-01

324

Complexation of lead with unicellular algae exudates  

Microsoft Academic Search

Release of exudates by freshwater algae may be different in polluted and non?polluted waters. The purpose of this work is to study the effect of lead on the unicellular green algae (Selenstrum capricornutum Printz), to find out if algae develop some defence mechanism against lead toxicity.Complexation studies were done in lead contaminated and uncontaminated (control) cultures, in exponential and stationary

Sofia Capelo; Ana M. Mota; Maria L. S. Gonçalves

1999-01-01

325

Evolution and functional diversification of fructose bisphosphate aldolase genes in photosynthetic marine diatoms.  

PubMed

Diatoms and other chlorophyll-c containing, or chromalveolate, algae are among the most productive and diverse phytoplankton in the ocean. Evolutionarily, chlorophyll-c algae are linked through common, although not necessarily monophyletic, acquisition of plastid endosymbionts of red as well as most likely green algal origin. There is also strong evidence for a relatively high level of lineage-specific bacterial gene acquisition within chromalveolates. Therefore, analyses of gene content and derivation in chromalveolate taxa have indicated particularly diverse origins of their overall gene repertoire. As a single group of functionally related enzymes spanning two distinct gene families, fructose 1,6-bisphosphate aldolases (FBAs) illustrate the influence on core biochemical pathways of specific evolutionary associations among diatoms and other chromalveolates with various plastid-bearing and bacterial endosymbionts. Protein localization and activity, gene expression, and phylogenetic analyses indicate that the pennate diatom Phaeodactylum tricornutum contains five FBA genes with very little overall functional overlap. Three P. tricornutum FBAs, one class I and two class II, are plastid localized, and each appears to have a distinct evolutionary origin as well as function. Class I plastid FBA appears to have been acquired by chromalveolates from a red algal endosymbiont, whereas one copy of class II plastid FBA is likely to have originated from an ancient green algal endosymbiont. The other copy appears to be the result of a chromalveolate-specific gene duplication. Plastid FBA I and chromalveolate-specific class II plastid FBA are localized in the pyrenoid region of the chloroplast where they are associated with ?-carbonic anhydrase, which is known to play a significant role in regulation of the diatom carbon concentrating mechanism. The two pyrenoid-associated FBAs are distinguished by contrasting gene expression profiles under nutrient limiting compared with optimal CO2 fixation conditions, suggestive of a distinct specialized function for each. Cytosolically localized FBAs in P. tricornutum likely play a role in glycolysis and cytoskeleton function and seem to have originated from the stramenopile host cell and from diatom-specific bacterial gene transfer, respectively. PMID:21903677

Allen, Andrew E; Moustafa, Ahmed; Montsant, Anton; Eckert, Angelika; Kroth, Peter G; Bowler, Chris

2012-01-01

326

Evolution and Functional Diversification of Fructose Bisphosphate Aldolase Genes in Photosynthetic Marine Diatoms  

PubMed Central

Diatoms and other chlorophyll-c containing, or chromalveolate, algae are among the most productive and diverse phytoplankton in the ocean. Evolutionarily, chlorophyll-c algae are linked through common, although not necessarily monophyletic, acquisition of plastid endosymbionts of red as well as most likely green algal origin. There is also strong evidence for a relatively high level of lineage-specific bacterial gene acquisition within chromalveolates. Therefore, analyses of gene content and derivation in chromalveolate taxa have indicated particularly diverse origins of their overall gene repertoire. As a single group of functionally related enzymes spanning two distinct gene families, fructose 1,6-bisphosphate aldolases (FBAs) illustrate the influence on core biochemical pathways of specific evolutionary associations among diatoms and other chromalveolates with various plastid-bearing and bacterial endosymbionts. Protein localization and activity, gene expression, and phylogenetic analyses indicate that the pennate diatom Phaeodactylum tricornutum contains five FBA genes with very little overall functional overlap. Three P. tricornutum FBAs, one class I and two class II, are plastid localized, and each appears to have a distinct evolutionary origin as well as function. Class I plastid FBA appears to have been acquired by chromalveolates from a red algal endosymbiont, whereas one copy of class II plastid FBA is likely to have originated from an ancient green algal endosymbiont. The other copy appears to be the result of a chromalveolate-specific gene duplication. Plastid FBA I and chromalveolate-specific class II plastid FBA are localized in the pyrenoid region of the chloroplast where they are associated with ?-carbonic anhydrase, which is known to play a significant role in regulation of the diatom carbon concentrating mechanism. The two pyrenoid-associated FBAs are distinguished by contrasting gene expression profiles under nutrient limiting compared with optimal CO2 fixation conditions, suggestive of a distinct specialized function for each. Cytosolically localized FBAs in P. tricornutum likely play a role in glycolysis and cytoskeleton function and seem to have originated from the stramenopile host cell and from diatom-specific bacterial gene transfer, respectively. PMID:21903677

Allen, Andrew E.; Moustafa, Ahmed; Montsant, Anton; Eckert, Angelika; Kroth, Peter G.; Bowler, Chris

2012-01-01

327

Aureochrome 1a is involved in the photoacclimation of the diatom Phaeodactylum tricornutum.  

PubMed

Aureochromes constitute a family of blue light (BL) receptors which are found exclusively in heterokont algae such as diatoms (Bacillariophyceae) and yellow-green algae (Xanthophyceae). Previous studies on the diatom Phaeodactylum tricornutum indicate that the formation of a high light acclimated phenotype is mediated by the absorption of BL and that aureochromes might play an important role in this process. P. tricornutum possesses four genes encoding aureochromes. In this study we confirm the nuclear localisation of the PtAUREO1a, 1b and 2 proteins. Furthermore we studied the physiology of light quality acclimation in genetically transformed P. tricornutum cell lines with reduced expression of the aureochrome 1a gene. The results demonstrate that the AUREO1a protein has a distinct function in light acclimation. However, rather unexpectedly AUREO1a seems to repress high light acclimation which resulted in a state of 'hyper' high light acclimation in aureo1a silenced strains. This was indicated by characteristic changes of several photosynthetic parameters, including increased maximum photosynthesis rates, decreased chlorophyll a contents per cell and increased values of non-photochemical quenching in AUREO1a silenced strains compared to wild type cultures. Strikingly, AUREO1a silenced strains exhibited phenotypic differences compared to wild type cells during cultivation under BL as well as under red light (RL) conditions. Therefore, AUREO1a might influence the RL signalling process, suggesting an interaction of AUREO1a with RL perception pathways. PMID:24073211

Schellenberger Costa, Benjamin; Sachse, Matthias; Jungandreas, Anne; Bartulos, Carolina Rio; Gruber, Ansgar; Jakob, Torsten; Kroth, Peter G; Wilhelm, Christian

2013-01-01

328

Diatom frustule photonic crystal geometric and optical characterization  

NASA Astrophysics Data System (ADS)

Diatom algae are single-celled, photosynthetic organisms with a cell wall called a frustule—a periodically patterned nano-structure made of silica. Throughout the last decade, diatom frustules have been studied for their potential uses as photonic crystals and biomimetic templates for artificially developed metamaterials. A MATLAB program characterizing their pore structure as a function of angle was developed, potentially giving insight into how their geometric characteristics determine their optical properties.

Mishler, Jonathan; Blake, Phillip; Alverson, Andrew J.; Roper, D. K.; Herzog, Joseph B.

2014-08-01

329

Recovery of algal oil from marine green macro-algae Enteromorpha intestinalis by acidic-hydrothermal process.  

PubMed

In this study, the recovery of algal oil from Enteromorpha intestinalis based on an acidic-hydrothermal reaction was investigated. Overall, the algal oil yield after the acidic-hydrothermal reaction was increased under the conditions of high reaction temperature, high catalyst concentration, and long reaction time within the tested ranges. Significantly, catalyst concentration, compared with reaction temperature and time, less affected algal oil recovery. The optimal acidic-hydrothermal reaction conditions for production of algal oil from E. intestinalis were as follows-200 °C reaction temperature, 2.92 % catalyst concentration, 54 min reaction time. Under these conditions, an 18.6 % algal oil yield was obtained. By increasing the combined severity factor, the algae oil recovery yield linearly increased. PMID:25055795

Jeong, Gwi-Taek; Hong, Yong-Ki; Lee, Hyung-Ho; Kong, In-Soo; Kim, Joong Kyun; Park, Nam Gyu; Kim, Sung-Koo; Park, Don-Hee

2014-09-01

330

Triassic origin and early radiation of multicellular volvocine algae  

E-print Network

Triassic origin and early radiation of multicellular volvocine algae Matthew D. Herron1 , Jeremiah-studied ETIs is the origin of multicellularity in the green alga Volvox, a model system for the evolution occurred dozens of times independently, for example in the red algae, brown algae, land plants, animals

331

The Development and Application of a Diatom-Based Quantitative Reconstruction Technique in Forensic Science  

Microsoft Academic Search

Diatoms are a group of unicellular algae that have been recorded and classified for over 200 years and have been used in a range of applications in forensic science. We have developed a quantitative diatom-based reconstruction technique to confirm drowning as a cause of death and localize the site of drowning in two recent, high-profile, case studies. In both case

Benjamin P. Horton; Steve Boreham; Caroline Hillier

2006-01-01

332

Copepod Population-Specific Response to a Toxic Diatom Diet  

PubMed Central

Diatoms are key phytoplankton organisms and one of the main primary producers in aquatic ecosystems. However, many diatom species produce a series of secondary metabolites, collectively termed oxylipins, that disrupt development in the offspring of grazers, such as copepods, that feed on these unicellular algae. We hypothesized that different populations of copepods may deal differently with the same oxylipin-producing diatom diet. Here we provide comparative studies of expression level analyses of selected genes of interest for three Calanus helgolandicus populations (North Sea, Atlantic Ocean and Mediterranean Sea) exposed to the same strain of the oxylipin-producing diatom Skeletonema marinoi using as control algae the flagellate Rhodomonas baltica. Expression levels of detoxification enzymes and stress proteins (e.g. glutathione S-transferase, glutathione synthase, superoxide dismutase, catalase, aldehyde dehydrogenases and heat shock proteins) and proteins involved in apoptosis regulation and cell cycle progression were analyzed in copepods after both 24 and 48 hours of feeding on the diatom or on a control diet. Strong differences occurred among copepod populations, with the Mediterranean population of C. helgolandicus being more susceptible to the toxic diet compared to the others. This study opens new perspectives for understanding copepod population-specific responses to diatom toxins and may help in underpinning the cellular mechanisms underlying copepod toxicity during diatom blooms. PMID:23056617

Lauritano, Chiara; Carotenuto, Ylenia; Miralto, Antonio; Procaccini, Gabriele; Ianora, Adrianna

2012-01-01

333

Seeing Toxic Algae Before it Blooms By Steve Ress  

E-print Network

Seeing Toxic Algae Before it Blooms By Steve Ress Researchers at the University of Nebraska of toxic blue-green algae before the bacteria that produce it can grow into a full-scale bloom. Now UNL and monitor in real-time, the water-borne agents that can cause toxic blue- green algae to flourish and become

Nebraska-Lincoln, University of

334

Green synthesis of silver nanoparticles using marine algae Caulerpa racemosa and their antibacterial activity against some human pathogens  

NASA Astrophysics Data System (ADS)

We present the synthesis and antibacterial activity of silver nanoparticles using Caulerpa racemosa, a marine algae. Fresh C. racemosa was collected from the Gulf of Mannar, Southeast coast of India. The seaweed extract was used for the synthesis of AgNO3 at room temperature. UV-visible spectrometry study revealed surface plasmon resonance at 413 nm. The characterization of silver nanoparticle was carried out using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscope (TEM). FT-IR measurements revealed the possible functional groups responsible for reduction and stabilization of the nanoparticles. X-ray diffraction analysis showed that the particles were crystalline in nature with face-centered cubic geometry.TEM micrograph has shown the formation of silver nanoparticles with the size in the range of 5-25 nm. The synthesized AgNPs have shown the best antibacterial activity against human pathogens such as Staphylococcus aureus and Proteus mirabilis. The above eco-friendly synthesis procedure of AgNPs could be easily scaled up in future for the industrial and therapeutic needs.

Kathiraven, T.; Sundaramanickam, A.; Shanmugam, N.; Balasubramanian, T.

2014-08-01

335

Lipid content and fatty acid composition of green algae Scenedesmus obliquus grown in a constant cell density apparatus  

NASA Technical Reports Server (NTRS)

The lipids of alga Scenedesmus obliquus grown under controlled conditions were separated and fractionated by column and thin-layer chromatography, and fatty acid composition of each lipid component was studied by gas-liquid chromatography (GLC). Total lipids were 11.17%, and neutral lipid, glycolipid and phospholipid fractions were 7.24%, 2.45% and 1.48% on a dry weight basis, respectively. The major neutral lipids were diglycerides, triglycerides, free sterols, hydrocarbons and sterol esters. The glycolipids were: monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. The phospholipids included: phosphatidyl choline, phosphatidyl glycerol and phosphatidyl ethanolamine. Fourteen fatty acids were identified in the four lipid fractions by GLC. The main fatty acids were C18:2, C16:0, C18:3(alpha), C18:1, C16:3, C16:1, and C16:4. Total unsaturated fatty acid and essential fatty acid compositions of the total algal lipids were 80% and 38%, respectively.

Choi, K. J.; Nakhost, Z.; Barzana, E.; Karel, M.

1987-01-01

336

Vulnerability of marine habitats to the invasive green alga Caulerpa racemosa var. cylindracea within a marine protected area.  

PubMed

The relative vulnerability of various habitat types to Caulerpa racemosa var. cylindracea invasion was investigated in the National Marine Park of Zakynthos (Ionian Sea, Greece). The density of C. racemosa fronds was modelled with generalized additive models for location, scale and shape (GAMLSS), based on an information theory approach. The species was present in as much as 33% of 748 randomly placed quadrats, which documents its aggressive establishment in the area. The probability of presence of the alga within randomly placed 20 x 20 cm quadrats was 83% on 'matte morte' (zones of fibrous remnants of a former Posidonia oceanica bed), 69% on rocky bottoms, 86% along the margins of P. oceanica meadows, 10% on sandy/muddy substrates, and 6% within P. oceanica meadows. The high frond density on 'matte morte' and rocky bottoms indicates their high vulnerability. The lowest frond density was observed within P. oceanica meadows. However, on the margins of P. oceanica meadows and within gaps in fragmented meadows relative high C. racemosa densities were observed. Such gaps within meadows represent spots of high vulnerability to C. racemosa invasion. PMID:20621771

Katsanevakis, Stelios; Issaris, Yiannis; Poursanidis, Dimitris; Thessalou-Legaki, Maria

2010-08-01

337

Lipid content and fatty acid composition of green algae Scenedesmus obliquus grown in a constant cell density apparatus.  

PubMed

The lipids of alga Scenedesmus obliquus grown under controlled conditions were separated and fractionated by column and thin-layer chromatography, and fatty acid composition of each lipid component was studied by gas-liquid chromatography (GLC). Total lipids were 11.17%, and neutral lipid, glycolipid and phospholipid fractions were 7.24%, 2.45% and 1.48% on a dry weight basis, respectively. The major neutral lipids were diglycerides, triglycerides, free sterols, hydrocarbons and sterol esters. The glycolipids were: monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. The phospholipids included: phosphatidyl choline, phosphatidyl glycerol and phosphatidyl ethanolamine. Fourteen fatty acids were identified in the four lipid fractions by GLC. The main fatty acids were C18:2, C16:0, C18:3(alpha), C18:1, C16:3, C16:1, and C16:4. Total unsaturated fatty acid and essential fatty acid compositions of the total algal lipids were 80% and 38%, respectively. PMID:11539709

Choi, K J; Nakhost, Z; Barzana, E; Karel, M

1987-01-01

338

Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii.  

PubMed

Cerium oxide nanoparticles (CeO2 NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO2 NP and effects on algae are largely unknown. In this study, the short term effects of CeO2 NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO2 NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO2 NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO2 NP had a surface charge of ?0mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO2 NP at pH 7.5 over 24h. This effect was exploited to test CeO2 NP dispersed in phosphate with a mean size of 140nm and agglomerated in absence of phosphate with a mean size of 2000nm. The level of dissolved cerium(III) in CeO2 NP suspensions was very low and between 0.1 and 27nM in all tested media. Exposure of C. reinhardtii to Ce(NO3)3 decreased the photosynthetic yield in a concentration dependent manner with EC50 of 7.5±0.84?M for wild type and EC50 of 6.3±0.53?M for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO3)3 with effective concentrations similar to those inhibiting photosynthesis. The agglomerated CeO2 NP caused a slight decrease of photosynthetic yield at the highest concentrations (100?M), while no effect was observed for dispersed CeO2 NP. The low toxicity of agglomerated CeO2 NP was attributed quantitatively to Ce(3+) ions co-occurring in the nanoparticle suspension whereas for dispersed CeO2 NP, dissolved Ce(3+) was precipitated with phosphate and not bioavailable. Furthermore CeO2 NP did not affect the intracellular ROS level. The cell wall free mutant and wild type of C. reinhardtii showed the same sensitivity to CeO2 NP and Ce(NO3)3, indicating a minor role of the cell wall on toxicity. For both algae strains, a flocculation of cells was observed upon exposure to agglomerated CeO2 NP and Ce(NO3)3, only algae exposed to agglomerated CeO2 NP were tightly packed in exopolymeric substances. PMID:24747084

Röhder, Lena A; Brandt, Tanja; Sigg, Laura; Behra, Renata

2014-07-01

339

RNAi knock-down of LHCBM1, 2 and 3 increases photosynthetic H2 production efficiency of the green alga Chlamydomonas reinhardtii.  

PubMed

Single cell green algae (microalgae) are rapidly emerging as a platform for the production of sustainable fuels. Solar-driven H2 production from H2O theoretically provides the highest-efficiency route to fuel production in microalgae. This is because the H2-producing hydrogenase (HYDA) is directly coupled to the photosynthetic electron transport chain, thereby eliminating downstream energetic losses associated with the synthesis of carbohydrate and oils (feedstocks for methane, ethanol and oil-based fuels). Here we report the simultaneous knock-down of three light-harvesting complex proteins (LHCMB1, 2 and 3) in the high H2-producing Chlamydomonas reinhardtii mutant Stm6Glc4 using an RNAi triple knock-down strategy. The resultant Stm6Glc4L01 mutant exhibited a light green phenotype, reduced expression of LHCBM1 (20.6% ±0.27%), LHCBM2 (81.2% ±0.037%) and LHCBM3 (41.4% ±0.05%) compared to 100% control levels, and improved light to H2 (180%) and biomass (165%) conversion efficiencies. The improved H2 production efficiency was achieved at increased solar flux densities (450 instead of ?100 µE m(-2) s(-1)) and high cell densities which are best suited for microalgae production as light is ideally the limiting factor. Our data suggests that the overall improved photon-to-H2 conversion efficiency is due to: 1) reduced loss of absorbed energy by non-photochemical quenching (fluorescence and heat losses) near the photobioreactor surface; 2) improved light distribution in the reactor; 3) reduced photoinhibition; 4) early onset of HYDA expression and 5) reduction of O2-induced inhibition of HYDA. The Stm6Glc4L01 phenotype therefore provides important insights for the development of high-efficiency photobiological H2 production systems. PMID:23613840

Oey, Melanie; Ross, Ian L; Stephens, Evan; Steinbeck, Janina; Wolf, Juliane; Radzun, Khairul Adzfa; Kügler, Johannes; Ringsmuth, Andrew K; Kruse, Olaf; Hankamer, Ben

2013-01-01

340

The mitochondrial genome of the red alga Kappaphycus striatus ("Green Sacol" variety): Complete nucleotide sequence, genome structure and organization, and comparative analysis.  

PubMed

The complete mitochondrial (mt) DNA sequence of the rhodophyte Kappaphycus striatus ("Green Sacol" variety) was determined. The mtDNA is circular, 25,242 bases long (A+T content: 69.94%), and contains 50 densely packed genes comprising 93.22% of the mitochondrial genome, with genes encoded on both strands. Through comparative analysis, the overall sequence, genome structure, and organization of K. striatus mtDNA were seen to be highly similar with other fully sequenced mitochondrial genomes of the class Florideophyceae. On the other hand, certain degrees of genome rearrangements and greater sequence dissimilarities were observed for the mtDNAs of other evolutionarily distant red algae, such as those from the class Bangiophyceae and Cyanidiophyceae, compared to that of K. striatus. Furthermore, a trend was observed wherein the red algal mtDNAs tend to encode lesser number of protein-coding genes, albeit not necessarily shorter, as the organism becomes more morphologically complex. This trend is supported by the phylogenetic tree inferred from the concatenated amino acid sequences of the deduced protein products of cytochrome c oxidase subunit genes (cox1, 2, and 3). PMID:24880120

Tablizo, Francis A; Lluisma, Arturo O

2014-12-01

341

Cytoskeletal alterations in interphase cells of the green alga Spirogyra decimina in response to heavy metals exposure: II. The effect of aluminium, nickel and copper.  

PubMed

The effect of the toxic metal ions, aluminium (Al3+), nickel (Ni2+), and copper (Cu2+), on both the actin and tubulin cytoskeleton of the green alga Spirogyra decimina was studied. Batch cultured cells were grown for different time intervals at concentrations of 10, 15, 40 and 100 microM of aluminium as AlCl3, nickel as NiCl2 and copper as CuSO(4).5H2O. The impact of copper on the morphology of both MTs and AFs was much more prominent than the other two metals. A rapid irreversible depolymerization of cytoskeletal structures occurred, whereas in the presence of aluminium or nickel, changes in the cytoskeleton were slight and reversible to some extent. Nickel changed the orientation of cortical MTs, which turned from a transverse to a skewed or longitudinal direction. Aluminium caused slight depolymerization of the cytoskeleton, which reverted spontaneously to the normal cytoskeletal state (in AlCl3 free nutrient solution). Copper exerted a strong effect on both the MT and AF cytoskeleton, which fragmented and disorganized rapidly. The extent of cytoskeletal damage by copper was dosage and time dependent and AFs were slightly more sensitive than MTs. PMID:18440197

Pribyl, Pavel; Cepák, Vladislav; Zachleder, Vilém

2008-08-01

342

Disruption of the microtubule network alters cellulose deposition and causes major changes in pectin distribution in the cell wall of the green alga, Penium margaritaceum  

PubMed Central

Application of the dintroaniline compound, oryzalin, which inhibits microtubule formation, to the unicellular green alga Penium margaritaceum caused major perturbations to its cell morphology, such as swelling at the wall expansion zone in the central isthmus region. Cell wall structure was also notably altered, including a thinning of the inner cellulosic wall layer and a major disruption of the homogalacturonan (HG)-rich outer wall layer lattice. Polysaccharide microarray analysis indicated that the oryzalin treatment resulted in an increase in HG abundance in treated cells but a decrease in other cell wall components, specifically the pectin rhamnogalacturonan I (RG-I) and arabinogalactan proteins (AGPs). The ring of microtubules that characterizes the cortical area of the cell isthmus zone was significantly disrupted by oryzalin, as was the extensive peripheral network of actin microfilaments. It is proposed that the disruption of the microtubule network altered cellulose production, the main load-bearing component of the cell wall, which in turn affected the incorporation of HG in the two outer wall layers, suggesting coordinated mechanisms of wall polymer deposition. PMID:24285826

Domozych, David S.

2014-01-01

343

Studies on the genetic variation of the green unicellular alga Haematococcus pluvialis (Chlorophyceae) obtained from different geographical locations using ISSR and RAPD molecular marker.  

PubMed

Haematococcus pluvialis (Flotow) is a unicellular green alga, which is considered to be the best astaxanthin-producing organism. Molecular markers are suitable tools for the purpose of finding out genetic variations in organisms; however there have been no studies conducted on ISSR or RAPD molecular markers for this organism. The DNA of 10 different strains of H. pluvialis (four strains from Iran, two strains from Finland, one strain from Switzerland and three strains from the USA) was extracted. A genetic similarity study was carried out using 14 ISSR and 12 RAPD primers. Moreover, the molecular weights of the bands produced ranged from 0.14 to 3.4 Kb. The PCA and dendrogram clustered the H. pluvialis strains into various groups according to their geographical origin. The lowest genetic similarity was between the Iran2 and USA2 strains (0.08) and the highest genetic similarity was between Finland1 and Finland2 (0.64). The maximum numbers of bands produced by the ISSR and RAPD primers were 35 and 6 bands, respectively. The results showed that ISSR and RAPD markers are useful for genetic diversity studies of Haematococcus as they showed geographical discrimination. PMID:21441863

Mostafa, Noroozi; Omar, Hishamuddin; Tan, Soon Guan; Napis, Suhaimi

2011-01-01

344

Structure-Function Mapping of Key Determinants for Hydrocarbon Biosynthesis by Squalene and Squalene Synthase-like Enzymes from the Green Alga Botryococcus braunii Race B.  

PubMed

Squalene and botryococcene are branched-chain, triterpene compounds that arise from the head-to-head condensation of two molecules of farnesyl diphosphate to yield 1'-1 and 1'-3 linkages, respectively. The enzymes that catalyze their formation have attracted considerable interest from the medical field as potential drug targets and the renewable energy sector for metabolic engineering efforts. Recently, the enzymes responsible for botryococcene and squalene biosynthesis in the green alga Botryococcus braunii race B were characterized. To better understand how the specificity for the 1'-1 and 1'-3 linkages was controlled, we attempted to identify the functional residues and/or domains responsible for this step in the catalytic cascade. Existing crystal structures for the mammalian squalene synthase and Staphylococcus dehydrosqualene synthase enzymes were exploited to develop molecular models for the B. braunii botryococcene and squalene synthase enzymes. Residues within the active sites that could mediate catalytic specificity were identified, and reciprocal mutants were created in an attempt to interconvert the reaction product specificity of the enzymes. We report here the identification of several amino acid positions contributing to the rearrangement of the cyclopropyl intermediate to squalene, but these same positions do not appear to be sufficient to account for the cyclopropyl rearrangement to give botryococcene. PMID:25393512

Bell, Stephen A; Niehaus, Thomas D; Nybo, S Eric; Chappell, Joseph

2014-12-01

345

RuBP limitation of photosynthetic carbon fixation during NH sub 3 assimilation: Interactions between photosynthesis, respiration, and ammonium assimilation in N-limited green algae  

SciTech Connect

The effects of ammonium assimilation on photosynthetic carbon fixation and O{sub 2} exchange were examined in two species of N-limited green algae, Chlorella pyrenoidosa and Selenastrum minutum. Under light-saturating conditions, ammonium assimilation resulted in a suppression of photosynthetic carbon fixation by S. minutum but not by C. pyrenoidosa. These different responses are due to different relationships between cellular ribulose bisphosphate (RuBP) concentration and the RuBP binding site density of ribulose bisphosphate carboxylase/oxygenase (Rubisco). In both species, ammonium assimilation resulted in a decrease in RuBP concentration. In S. minutum the concentration fell below the RuBP binding site density of Rubisco, indicating RuBP limitation of carboxylation. In contrast, RuBP concentration remained above the binding site density in C. pyrenoidosa. Compromising RuBP regeneration in C. pyrenoidosa with low light resulted in an ammonium-induced decrease in RuBP concentration below the RuBP binding site density of Rubisco. This resulted in a decrease in photosynthetic carbon fixation. In both species, ammonium assimilation resulted in a larger decrease in net O{sub 2} evolution than in carbon fixation. Mass spectrometric analysis shows this to be a result of an increase in the rate of mitochondrial respiration in the light.

Elrifi, I.R.; Holmes, J.J.; Weger, H.G.; Mayo, W.P.; Turpin, D.H. (Queen's Univ., Kingston, Ontario (Canada))

1988-06-01

346

Stable transformation and reverse genetic analysis of Penium margaritaceum: a platform for studies of charophyte green algae, the immediate ancestors of land plants.  

PubMed

The charophyte green algae (CGA, Streptophyta, Viridiplantae) occupy a key phylogenetic position as the immediate ancestors of land plants but, paradoxically, are less well-studied than the other major plant lineages. This is particularly true in the context of functional genomic studies, where the lack of an efficient protocol for their stable genetic transformation has been a major obstacle. Observations of extant CGA species suggest the existence of some of the evolutionary adaptations that had to occur for land colonization; however, to date, there has been no robust experimental platform to address this genetically. We present a protocol for high-throughput Agrobacterium tumefaciens-mediated transformation of Penium margaritaceum, a unicellular CGA species. The versatility of Penium as a model for studying various aspects of plant cell biology and development was illustrated through non-invasive visualization of protein localization and dynamics in living cells. In addition, the utility of RNA interference (RNAi) for reverse genetic studies was demonstrated by targeting genes associated with cell wall modification (pectin methylesterase) and biosynthesis (cellulose synthase). This provided evidence supporting current models of cell wall assembly and inter-polymer interactions that were based on studies of land plants, but in this case using direct observation in vivo. This new functional genomics platform has broad potential applications, including studies of plant organismal biology and the evolutionary innovations required for transition from aquatic to terrestrial habitats. PMID:24308430

Sřrensen, Iben; Fei, Zhangjun; Andreas, Amanda; Willats, William G T; Domozych, David S; Rose, Jocelyn K C

2014-02-01

347

Toxic peptides from freshwater cyanobacteria (blue-green algae). I. Isolation, purification and characterization of peptides from Microcystis aeruginosa and Anabaena flos-aquae.  

PubMed

Toxic peptides from two European Microcystis aeruginosa and one Canadian Anabaena flos-aquae species of freshwater cyanobacteria (blue-green algae) were purified by high performance liquid chromatography (HPLC) and examined by amino acid analysis and mass spectrometry. A toxic fraction from a butanol/methanol extract of toxic lyophilized cells was separated by G-25 gel filtration and purified by HPLC using a C-18 semi-preparative Column. A toxic peak with the same elution time was detected for each of the three toxic cyanobacteria. The desalted purified toxins (i.p. LD50 in mice, 50 micrograms/kg) caused signs of poisoning identical with previous literature reports of hepatotoxic peptides from Microcystis. On hydrolysis and amino acid analysis all three toxins showed a similar profile, consisting of equimolar amounts of glutamic acid, alanine, arginine and leucine. beta-methyl aspartic acid was identified in all of the toxic peptides. The fast atom bombardment mass spectra of the toxins indicated the molecular weight to be 994 for all the peptides. The absence of sequence ions in their corresponding fast atom bombardment mass spectra indicated the peptides to be cyclic. PMID:3101230

Krishnamurthy, T; Carmichael, W W; Sarver, E W

1986-01-01

348

In vitro and in vivo safety assessment of edible blue-green algae, Nostoc commune var. sphaeroides Kützing and Spirulina plantensis  

PubMed Central

Blue-green algae (BGA) have been consumed as food and herbal medicine for centuries. However, safety for their consumption has not been well investigated. This study was undertaken to evaluate in vitro and in vivo toxicity of cultivated Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP). Neither NO nor SP contained detectable levels of microcystin (MC)-LA, MC-RR, MC-LW and MC-LR by LC/MS/MS. Cell viability remained ~70-80% when HepG2 cells were incubated with 0-500 ?g/ml of hexane, chloroform, methanol and water-extractable fractions of NO and SP. Four-week-old male and female C57BL/6J mice were fed an AIN-93G/M diet supplemented with 0, 2.5% or 5% of NO and SP (wt/wt) for 6 months. For both genders, BGA-rich diets did not induce noticeable abnormality in weight gain and plasma alanine aminotransferase (ALT) and aspartate aminotransferase concentrations except a significant increase in plasma ALT levels by 2.5% NO supplementation in male mice at 6 month. Histopathological analysis of livers, however, indicated that BGA did not cause significant liver damage compared with controls. In conclusion, our results suggest that NO and SP are free of MC and the long-term dietary supplementation of up to 5% of the BGA may be consumed without evident toxic side-effects. PMID:21473896

Yang, Yue; Park, Youngki; Cassada, David A.; Snow, Daniel D.; Rogers, Douglas G.; Lee, Jiyoung

2011-01-01

349

Improved method for the determination of anatoxin-a and two of its metabolites in blue-green algae using liquid chromatography with fluorescence detection.  

PubMed

Anatoxin-a, a neurotoxin produced by blue-green algae (BGA) species, can cause death to exposed organisms. In North America, BGA are harvested and sold as food supplements, some of which contain elevated levels of other algal toxins, such as microcystins. Concern that elevated levels of anatoxin-a also may be present in BGA food supplements has led to the development of a simple method to determine the presence of anatoxin-a in BGA. Some researchers have successfully analyzed this compound using liquid chromatography with fluorescence detection by forming a fluorescent derivative with 4-fluoro-7-nitrobenzofurazan (NBD-F) in water and phytoplankton extracts. With this method, the background noise is high in BGA extracts due to the presence of co-extractives. Addition of o-phthaldialdehyde (OPA) and mercaptoethanol to the extract before addition of the NBD-F resulted in the successful removal of primary amines from the background noise when the NBD-F derivatives were detected with fluorescence. Improved chromatograms were obtained when extracts were cleaned up in this manner, leading to a lower detection limit (approximately 50 microg/kg) for anatoxin-a. The detection limits obtained for the 2 degradation products dihydroanatoxin-a and epoxyanatoxin-a in BGA extracts were similarly low (55 and 65 microg/kg, respectively). PMID:16526457

Rawn, Dorothea F K; Lau, Benjamin P Y; Niedzwiadek, Barbara; Lawrence, James F

2005-01-01

350

Contamination by Microcystis and microcystins of blue-green algae food supplements (BGAS) on the Italian market and possible risk for the exposed population.  

PubMed

Blue green algae supplements (BGAS) are generally proposed as health-promoting natural products for their purported beneficial effects. Spirulina spp. and Aphanizomenon flos aquae are mainly used in BGAS production. They are usually collected from the natural environment, where other potentially toxic cyanobacteria can be present, making possible BGAS contamination by cyanotoxins, with potential risk for human health. In this work we apply a combined approach, by using chemical and molecular techniques, on BGAS of 17 brands available in Italy. Samples containing Spirulina-only were free of contamination. The Aphanizomenon flos aquae-based samples were contaminated by highly variable levels of microcystins (MC-LR and MC-LA congeners), up to 5.2 ?g MC-LR equivalents per gram product. The highest variability (up to 50 fold) was among batches of the same brand, although intra-batch differences were also evidenced. PCR analyses were positive only for the presence of Microcystis sp., identified as the toxin-producing species responsible for contamination. At the maximum contamination levels found, a risk for consumers can be expected following chronic or sub-chronic exposure to a reasonable daily BGAS consumption of 4 g. The need for a strict monitoring by producers and Health Authority to assure an adequate protection for consumers is underscored. PMID:23036452

Vichi, Susanna; Lavorini, Paolo; Funari, Enzo; Scardala, Simona; Testai, Emanuela

2012-12-01

351

A pyruvate formate lyase-deficient Chlamydomonas reinhardtii strain provides evidence for a link between fermentation and hydrogen production in green algae.  

PubMed

The green alga Chlamydomonas reinhardtii has a complex anaerobic metabolism characterized by a plastidic hydrogenase (HYD1) coupled to photosynthesis and a bacterial-type fermentation system in which pyruvate formate lyase (PFL1) is the central fermentative enzyme. To identify mutant strains with altered hydrogen metabolism, a C. reinhardtii nuclear transformant library was screened. Mutant strain 48F5 showed lower light-dependent hydrogen (H?) evolution rates and reduced in vitro hydrogenase activity, and fermentative H? production in the dark was enhanced. The transformant has a single integration of the paromomycin resistance cassette within the PFL1 gene, and is unable to synthesize PFL1 protein. 48F5 secretes no formate, but produces more ethanol, D-lactate and CO? than the wild type. Moreover, HYD1 transcript and HYD1 protein levels were lower in the pfl1 mutant strain. Complementation of strain 48F5 with an intact copy of the PFL1 gene restored formate excretion and hydrogenase activity to the wild type level. This analysis shows that the PFL1 pathway has a significant impact on hydrogen metabolism in C. reinhardtii. PMID:21219510

Philipps, Gabriele; Krawietz, Danuta; Hemschemeier, Anja; Happe, Thomas

2011-04-01

352

Nitrogen Limitation and Slow Drying Induce Desiccation Tolerance in Conjugating Green Algae (Zygnematophyceae, Streptophyta) from Polar Habitats  

PubMed Central

Background Filamentous Zygnematophyceae are typical components of algal mats in the polar hydro-terrestrial environment. Under field conditions, they form senescent vegetative cells, designated as pre-akinetes, which are tolerant to desiccation and osmotic stress. Key Findings Pre-akinete formation and desiccation tolerance was investigated experimentally under monitored laboratory conditions in four strains of Arctic and Antarctic isolates with vegetative Zygnema sp. morphology. Phylogenetic analyses of rbcL sequences revealed one Arctic strain as genus Zygnemopsis, phylogenetically distant from the closely related Zygnema strains. Algae were cultivated in liquid or on solidified medium (9 weeks), supplemented with or lacking nitrogen. Nitrogen-free cultures (liquid as well as solidified) consisted of well-developed pre-akinetes after this period. Desiccation experiments were performed at three different drying rates (rapid: 10% relative humidity, slow: 86% rh and very slow); viability, effective quantum yield of PS II, visual and ultrastructural changes were monitored. Recovery and viability of pre-akinetes were clearly dependent on the drying rate: slower desiccation led to higher levels of survival. Pre-akinetes survived rapid drying after acclimation by very slow desiccation. Conclusions The formation of pre-akinetes in polar Zygnema spp. and Zygnemopsis sp. is induced by nitrogen limitation. Pre-akinetes, modified vegetative cells, rather than specialized stages of the life cycle, can be hardened by mild desiccation stress to survive rapid drying. Naturally hardened pre-akinetes play a key role in stress tolerance and dispersal under the extreme conditions of polar regions, where sexual reproduction and production of dormant stages is largely suppressed. PMID:25398135

Pichrtová, Martina; Kulichová, Jana; Holzinger, Andreas

2014-01-01

353

Diatoms (50 Species)  

USGS Multimedia Gallery

Photomicrograph depicting the siliceous frustules of fifty species of diatoms arranged within a circular shape. Diatoms form the base of many marine and aquatic food chains and upon death, their glassy frustules form sediments known as diatomaceous earth....

354

Diatoms (50 Species)  

USGS Multimedia Gallery

Photomicrograph depicting the siliceous frustulesof fifty species of diatoms arranged within a circular shape. Diatoms form the base of many marine and aquatic food chains and upon death, their glassy frustules form sediments known as diatomaceous earth....

355

On the relative efficiency of two- vs. one-stage production of astaxanthin by the green alga Haematococcus pluvialis.  

PubMed

Haematococcus pluvialis under stress conditions overproduces the valuable red ketocarotenoid astaxanthin. Two proposed strategies for commercial production are under current analysis. One separates in time the production of biomass (optimal growth, green stage) and pigment (permanent stress, red stage), while the other uses an approach based on continuous culture under limiting stress at steady state. The productivities, efficiencies and yields for the pigment accumulation in each case have been compared and analyzed in terms of the algal basic physiology. The two-stage system indoors yields a richer astaxanthin product (4% of dry biomass) with a final astaxanthin productivity of 11.5 mg L(-1) day(-1), is more readily upscalable and amenable to outdoors production. Furthermore, each stage can be optimized for green biomass growth and red pigment accumulation by adjusting independently the respective ratio of effective irradiance to cell density. We conclude that the two-stage system performs better (by a factor of 2.5-5) than the one-stage system, and the former is best fit in an efficient mass production setup. PMID:17318905

Aflalo, Claude; Meshulam, Yuval; Zarka, Aliza; Boussiba, Sammy

2007-09-01

356

Analysis of LhcSR3, a protein essential for feedback de-excitation in the green alga Chlamydomonas reinhardtii.  

PubMed

In photosynthetic organisms, feedback dissipation of excess absorbed light energy balances harvesting of light with metabolic energy consumption. This mechanism prevents photodamage caused by reactive oxygen species produced by the reaction of chlorophyll (Chl) triplet states with O?. Plants have been found to perform the heat dissipation in specific proteins, binding Chls and carotenoids (Cars), that belong to the Lhc family, while triggering of the process is performed by the PsbS subunit, needed for lumenal pH detection. PsbS is not found in algae, suggesting important differences in energy-dependent quenching (qE) machinery. Consistent with this suggestion, a different Lhc-like gene product, called LhcSR3 (formerly known as LI818) has been found to be essential for qE in Chlamydomonas reinhardtii. In this work, we report the production of two recombinant LhcSR isoforms from C. reinhardtii and their biochemical and spectroscopic characterization. We found the following: (i) LhcSR isoforms are Chl a/b- and xanthophyll-binding proteins, contrary to higher plant PsbS; (ii) the LhcSR3 isoform, accumulating in high light, is a strong quencher of Chl excited states, exhibiting a very fast fluorescence decay, with lifetimes below 100 ps, capable of dissipating excitation energy from neighbor antenna proteins; (iii) the LhcSR3 isoform is highly active in the transient formation of Car radical cation, a species proposed to act as a quencher in the heat dissipation process. Remarkably, the radical cation signal is detected at wavelengths corresponding to the Car lutein, rather than to zeaxanthin, implying that the latter, predominant in plants, is not essential; (iv) LhcSR3 is responsive to low pH, the trigger of non-photochemical quenching, since it binds the non-photochemical quenching inhibitor dicyclohexylcarbodiimide, and increases its energy dissipation properties upon acidification. This is the first report of an isolated Lhc protein constitutively active in energy dissipation in its purified form, opening the way to detailed molecular analysis. Owing to its protonatable residues and constitutive excitation energy dissipation, this protein appears to merge both pH-sensing and energy-quenching functions, accomplished respectively by PsbS and monomeric Lhcb proteins in plants. PMID:21267060

Bonente, Giulia; Ballottari, Matteo; Truong, Thuy B; Morosinotto, Tomas; Ahn, Tae K; Fleming, Graham R; Niyogi, Krishna K; Bassi, Roberto

2011-01-01

357

LIFETIME OF THE EXCITED STATE IN VIVO I. CHLOROPHYLL a IN ALGAE, AT ROOM  

E-print Network

LIFETIME OF THE EXCITED STATE IN VIVO I. CHLOROPHYLL a IN ALGAE, AT ROOM AND AT LIQUID NITROGEN decay of chloro- phyll (Chl) a in the green alga Chlorella pyrenoidosa, the red alga Porphyridium cruentum, and the blue-green alga Anacystis nidulans was measured by the phase- shift method under

Govindjee

358

Plant & CellPhysiol. 14: 1081-1097 (1973) Photophosphorylation in intact algae: Effects of  

E-print Network

Plant & CellPhysiol. 14: 1081-1097 (1973) Photophosphorylation in intact algae: Effects alga Chlorella pyrenoidosa and of the blue-green alga Anacystis nidulans. A few measurements in extracts from intact cells of the green alga Chlorella in the early 1950's (3, 4), few workers measured

Govindjee

359

Mass Production of Biodiesel From Algae UROP Summer 2008 Project Proposal  

E-print Network

1 Mass Production of Biodiesel From Algae UROP Summer 2008 Project Proposal Steven A. Biorn Faculty energy products from algae. The first step in this process is to select species of algae with high growth of green algae. Once the oils have been extracted, the remnants of the algae contain protein, starches

Minnesota, University of

360

FLUORESCENCE QUENCHING AND THE DIADINOXANTHIN CYCLE IN A MARINE DIATOM  

EPA Science Inventory

The diadinoxanthin cycle (DD-cycle) in chromophyta algae involves the interconversion of two carotenoids, diadinoxanthin (DD) and diatoxanthin (DT). e investigated the kinetics of light-induced DD-cycling in the marine diatom Phaeodactylum triconutum and its role in dissipating e...

361

The ferredoxin-thioredoxin system of a green alga, Chlamydomonas reinhardtii: identification and characterization of thioredoxins and ferredoxin-thioredoxin reductase components  

NASA Technical Reports Server (NTRS)

The components of the ferredoxin-thioredoxin (FT) system of Chlamydomonas reinhardtii have been purified and characterized. The system resembled that of higher plants in consisting of a ferredoxin-thioredoxin reductase (FTR) and two types of thioredoxin, a single f and two m species, m1 and m2. The Chlamydomonas m and f thioredoxins were antigenically similar to their higher-plant counterparts, but not to one another. The m thioredoxins were recognized by antibodies to both higher plant m and bacterial thioredoxins, whereas the thioredoxin f was not. Chlamydomonas thioredoxin f reacted, although weakly, with the antibody to spinach thioredoxin f. The algal thioredoxin f differed from thioredoxins studied previously in behaving as a basic protein on ion-exchange columns. Purification revealed that the algal thioredoxins had molecular masses (Mrs) typical of thioredoxins from other sources, m1 and m2 being 10700 and f 11500. Chlamydomonas FTR had two dissimilar subunits, a feature common to all FTRs studied thus far. One, the 13-kDa ("similar") subunit, resembled its counterpart from other sources in both size and antigenicity. The other, 10-kDa ("variable") subunit was not recognized by antibodies to any FTR tested. When combined with spinach, (Spinacia oleracea L.) thylakoid membranes, the components of the FT system functioned in the light activation of the standard target enzymes from chloroplasts, corn (Zea mays L.) NADP-malate dehydrogenase (EC 1.1.1.82) and spinach fructose 1,6-bisphosphatase (EC 3.1.3.11) as well as the chloroplast-type fructose 1,6-bisphosphatase from Chlamydomonas. Activity was greatest if ferredoxin and other components of the FT system were from Chlamydomonas. The capacity of the Chlamydomonas FT system to activate autologous FBPase indicates that light regulates the photosynthetic carbon metabolism of green algae as in other oxygenic photosynthetic organisms.

Huppe, H. C.; de Lamotte-Guery, F.; Buchanan, B. B.

1990-01-01

362

Litorimonas cladophorae sp. nov., a new alphaproteobacterium isolated from the Pacific green alga Cladophora stimpsoni, and emended descriptions of the genus Litorimonas and Litorimonas taeaensis.  

PubMed

A strictly aerobic, Gram-stain-negative, rod-shaped and red-orange pigmented bacterium, designated strain KMM 6395(T), was isolated from the green alga Cladophora stimpsoni and subjected to a polyphasic taxonomic study. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the novel strain affiliated to the family Hyphomonadaceae of the class Alphaproteobacteria being most closely related to the type strain of the single species of the genus Litorimonas, Litorimonas taeanensis G5(T), with 16S rRNA gene sequence similarity of 96.8 %. Strain KMM 6395(T) grew with 1-5 % NaCl and at 4-35 °C, hydrolysed starch and Tween 80. The DNA G+C content was 48.7 mol%. The prevalent fatty acids were C18:1 ?7c, C19:1 ?8c and C18:1 ?7c 10-methyl. The polar lipid profile was characterized by the presence of phosphatidylglycerol, monoglycosyldiglyceride, glucuronopyranosyldiglyceride and an unidentified glycolipid. The major respiratory quinone was Q-10. The significant molecular distinctiveness between the novel isolate and its nearest neighbour, L. taeanensis G5(T), were strongly supported by the differences in physiological and biochemical tests. Therefore, strain KMM 6395(T) represents a novel species of the genus Litorimonas, for which the name Litorimonas cladophorae sp. nov. is proposed. The type strain is KMM 6395(T) (=KCTC 23968(T) = LMG 26985(T)). The emended descriptions of the genus Litorimonas and L. taeaensis are also provided. PMID:23525880

Nedashkovskaya, Olga I; Kukhlevskiy, Andrey D; Zhukova, Natalia V; Kim, So-Jeong; Rhee, Sung-Keun

2013-06-01

363

Effects of Long-Term Supplementation of Blue-Green Algae on Lipid Metabolism in C57BL/6J mice  

PubMed Central

Dyslipidemia is a primary risk factor for cardiovascular disease. In this study, we investigated the effect of long-term supplementation of two blue-green algae (BGA) species, i.e., Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), on lipid metabolism in vivo. Male C57BL/6J mice were fed an AIN-93G/M diet supplemented with 2.5 or 5% (wt/wt) NO or SP for 6 months. Mice fed NO and SP showed lower plasma total cholesterol (TC) and triglyceride (TG) concentrations than control at certain months during 6 month experimental period. Both BGA supplementation for 6 months significantly increased hepatic TC contents whereas SP-fed groups had significantly less TG levels in the liver compared with control and NO groups. None of BGA-fed animals showed significantly different mRNA levels of sterol regulatory element binding protein 2, while 3-hydroxy-3-methylglutaryl coenzyme A reductase and low-density lipoprotein receptor (LDLR) expression was higher in NO groups than the other groups in the liver. Furthermore, NO supplementation increased the hepatic expression of acetyl-CoA carboxylase 1, stearoyl CoA desaturase 1, carnitine palmitoyltransferase 1?, and acyl-CoA oxidase 1 but SP did not elicit any significant changes in mRNA levels of the genes compared with control. LDLR protein level was significantly higher in NO 2.5% and SP 5%, as compared to the control and NO 5% groups; while the level of fatty acid synthase protein in the liver was significantly higher in NO 5% and SP 5%, than that in the control group. In conclusion, our results suggest that long-term supplementation of NO and SP decreased plasma TC and TG concentrations. Therefore, supplementation of NO and SP may be potentially beneficial for preventing dyslipidemia-associated chronic diseases.

Yang, Yue; Kim, Bohkyung; Park, Young-Ki; Lee, Ji-Young

2014-01-01

364

Edible blue-green algae reduce the production of pro-inflammatory cytokines by inhibiting NF-?B pathway in macrophages and splenocytes  

PubMed Central

Background Chronic inflammation contributes to the development of pathological disorders including insulin resistance and atherosclerosis. Identification of anti-inflammatory natural products can prevent the inflammatory diseases. Methods Anti-inflammatory effects of blue-green algae (BGA), i.e., Nostoc commune var. Sphaeroides Kützing (NO) and Spirulina Platensis (SP), were compared in RAW 264.7 and mouse bone marrow-derived macrophages (BMM) as well as splenocytes from apolipoprotein E knockout (apoE?/?) mice fed BGA. Results When macrophages pretreated with 100 ?g/ml NO lipid extract (NOE) or SP lipid extract (SPE) were activated by lipopolysaccharide (LPS), expression and secretion of pro-inflammatory cytokines, such as tumor necrosis factor ? (TNF?), interleukin 1? (IL-1?), and IL-6, were significantly repressed. NOE and SPE also significantly repressed the expression of TNF? and IL-1? in BMM. LPS-induced secretion of IL-6 was lower in splenocytes from apoE?/? fed an atherogenic diet containing 5% NO or SP for 12 weeks. In RAW 264.7 macrophages, NOE and SPE markedly decreased nuclear translocation of NF-?B. The degree of repression of pro-inflammatory gene expression by algal extracts was much stronger than that of SN50, an inhibitor of NF-?B nuclear translocation. Trichostatin A, a pan histone deacetylase inhibitor, increased basal expression of IL-1? and attenuated the repression of the gene expression by SPE. SPE significantly down-regulated mRNA abundance of 11 HDAC isoforms, consequently increasing acetylated histone 3 levels. Conclusion NOE and SPE repress pro-inflammatory cytokine expression and secretion in macrophages and splenocytes via inhibition of NF-?B pathway. Histone acetylation state is likely involved in the inhibition. General significance This study underscores natural products can exert anti-inflammatory effects by epigenetic modifications such as histone acetylation. PMID:23357040

Ku, Chai Siah; Pham, Tho X.; Park, Youngki; Kim, Bohkyung; Shin, Min; Kang, Insoo; Lee, Jiyoung

2013-01-01

365

Air-Drying of Cells, the Novel Conditions for Stimulated Synthesis of Triacylglycerol in a Green Alga, Chlorella kessleri  

PubMed Central

Triacylglycerol is used for the production of commodities including food oils and biodiesel fuel. Microalgae can accumulate triacylglycerol under adverse environmental conditions such as nitrogen-starvation. This study explored the possibility of air-drying of green algal cells as a novel and simple protocol for enhancement of their triacylglycerol content. Chlorella kessleri cells were fixed on the surface of a glass fibre filter and then subjected to air-drying with light illumination. The dry cell weight, on a filter, increased by 2.7-fold in 96 h, the corresponding chlorophyll content ranging from 1.0 to 1.3-fold the initial one. Concomitantly, the triacylglycerol content remarkably increased to 70.3 mole% of fatty acids and 15.9% (w/w), relative to total fatty acids and dry cell weight, respectively, like in cells starved of nitrogen. Reduction of the stress of air-drying by placing the glass filter on a filter paper soaked in H2O lowered the fatty acid content of triacylglycerol to 26.4 mole% as to total fatty acids. Moreover, replacement of the H2O with culture medium further decreased the fatty acid content of triacylglycerol to 12.2 mole%. It thus seemed that severe dehydration is required for full induction of triacylglycerol synthesis, and that nutritional depletion as well as dehydration are crucial environmental factors. Meanwhile, air-drying of Chlamydomonas reinhardtii cells increased the triacylglycerol content to only 37.9 mole% of fatty acids and 4.8% (w/w), relative to total fatty acids and dry cell weight, respectively, and a marked decrease in the chlorophyll content, on a filter, of 33%. Air-drying thus has an impact on triacylglycerol synthesis in C. reinhardtii also, however, the effect is considerably limited, owing probably to instability of the photosynthetic machinery. This air-drying protocol could be useful for the development of a system for industrial production of triacylglycerol with appropriate selection of the algal species. PMID:24260270

Minoda, Ayumi; Tsuzuki, Mikio; Sato, Norihiro

2013-01-01

366

The Study of Algae  

ERIC Educational Resources Information Center

Included in this introduction to the study of algae are drawings of commonly encountered freshwater algae, a summary of the importance of algae, descriptions of the seven major groups of algae, and techniques for collection and study of algae. (CS)

Rushforth, Samuel R.

1977-01-01

367

Stochastic Forecasting of Algae Blooms in Lakes  

SciTech Connect

We consider the development of harmful algae blooms (HABs) in a lake with uncertain nutrients inflow. Two general frameworks, Fokker-Planck equation and the PDF methods, are developed to quantify the resultant concentration uncertainty of various algae groups, via deriving a deterministic equation of their joint probability density function (PDF). A computational example is examined to study the evolution of cyanobacteria (the blue-green algae) and the impacts of initial concentration and inflow-outflow ratio.

Wang, Peng; Tartakovsky, Daniel M.; Tartakovsky, Alexandre M.

2013-01-15

368

Toxicity of lead (Pb) to freshwater green algae: development and validation of a bioavailability model and inter-species sensitivity comparison.  

PubMed

Scientifically sound risk assessment and derivation of environmental quality standards for lead (Pb) in the freshwater environment are hampered by insufficient data on chronic toxicity and bioavailability to unicellular green algae. Here, we first performed comparative chronic (72-h) toxicity tests with three algal species in medium at pH 6, containing 4 mg fulvic acid (FA)/L and containing organic phosphorous (P), i.e. glycerol-2-phosphate, instead of PO4(3-) to prevent lead-phosphate mineral precipitation. Pseudokirchneriella subcapitata was 4-fold more sensitive to Pb than Chlorella kesslerii, with Chlamydomonas reinhardtii in the middle. The influence of medium physico-chemistry was therefore investigated in detail with P. subcapitata. In synthetic test media, higher concentrations of fulvic acid or lower pH protected against toxicity of (filtered) Pb to P. subcapitata, while effects of increased Ca or Mg on Pb toxicity were less clear. When toxicity was expressed on a free Pb(2+) ion activity basis, a log-linear, 260-fold increase of toxicity was observed between pH 6.0 and 7.6. Effects of fulvic acid were calculated to be much more limited (1.9-fold) and were probably even non-existent (depending on the affinity constant for Pb binding to fulvic acid that was used for calculating speciation). A relatively simple bioavailability model, consisting of a log-linear pH effect on Pb(2+) ion toxicity linked to the geochemical speciation model Visual Minteq (with the default NICA-Donnan description of metal and proton binding to fulvic acid), provided relatively accurate toxicity predictions. While toxicity of (filtered) Pb varied 13.7-fold across 14 different test media (including four Pb-spiked natural waters) with widely varying physico-chemistry (72h-EC50s between 26.6 and 364 ?g/L), this bioavailability model displayed mean and maximum prediction errors of only 1.4 and 2.2-fold, respectively, thus indicating the potential usefulness of this bioavailability model to reduce uncertainty in site-specific risk assessment. A model-based comparison with other species indicated that the sensitivity difference between P. subcapitata and two of the most chronically Pb-sensitive aquatic invertebrates (the crustacean Ceriodaphnia dubia and the snail Lymnaea stagnalis) is strongly pH dependent, with P. subcapitata becoming the most sensitive of the three at pH > 7.4. This indicates that inter-species differences in Pb bioavailability relationships should be accounted for in risk assessment and in the derivation of water quality criteria or environmental quality standards for Pb. The chronic toxicity data with three algae species and the bioavailability model presented here will help to provide a stronger scientific basis for evaluating ecological effects of Pb in the freshwater environment. PMID:25089923

De Schamphelaere, K A C; Nys, C; Janssen, C R

2014-10-01

369

Diatom-based label-free optical biosensor for biomolecules.  

PubMed

Diatoms are unicellular algae, which fabricates ornate biosilica shells called frustules that possess a surface rich in reactive silanol (Si-OH) groups. The intrinsic patterned porous structure of diatom frustules at nanoscale can be exploited in the effective detection of biomolecules. In this study, the frustules of a specific diatom Amphora sp. has been functionalized to detect bovine serum albumin (BSA). The functionalization of the diatom frustule substrate is achieved by using 3-aminopropyltriethoxysilane (APES). The field emission scanning electron microscopy (FESEM) results showed an ornately patterned surface of the frustule valve ordered at nanoscale. The Fourier transform infrared (FTIR) spectra confirmed the N-H bending and stretching of the amine group after amine functionalization. The emission peaks in the photoluminescence (PL) spectra of the amine-functionalized diatom biosilica selectively enhanced the intensity by a factor of ten when compared to that of a bare diatom biosilica. The result showed a significant quenching of PL intensity of BSA at around 445 nm due to the interaction of amine-functionalized diatom-BSA protein complex. The detection limit was found to be 3?×?10(-5) M of BSA protein. Hence, the study proves that the functionalized frustule of Amphora sp. is an effective quantitative analytical tool for optical label-free biosensing applications. PMID:24989453

Viji, S; Anbazhagi, M; Ponpandian, N; Mangalaraj, D; Jeyanthi, S; Santhanam, P; Devi, A Shenbaga; Viswanathan, C

2014-10-01

370

Algae Experiments  

NSDL National Science Digital Library

This two-part lesson offers students the opportunity to view two types of algae (freshwater and Great Salt Lake species) and assess the survival of each when placed in altered habitats. Students will make observations and record their observations on a recording sheet where they will describe what they see through drawing and words. They will help prepare slides of algae and will learn to identify different qualities such as cell structure, movement and other behavioristic qualities of the two different types of algae. The resource includes background knowledge, reference to Utah elementary core curriculum standards, prior resource assessment, reproducible handouts, materials list, teaching recommendations, and final assessment strategies.

Duffy, Kim; Project, Westminster C.

371

GRAZER CONTROL OF STREAM ALGAE :M ODELING TEMPERATURE AND FLOOD EFFECTS  

Microsoft Academic Search

A computer model for epilithic algae and grazer biomass in streams is modified to better predict the effects of temperature and is calibrated for diatoms and mayflies. Mayflies are predicted to maintain low diatom biomass provided that (1) temperatures remain within their preferred range (10-207C); and (2) mayfly populations are not adversely affected by floods. Algal blooms are predicted to

J. C. Rutherford; M. R. Scarsbrook; N. Broekhuizen

2000-01-01

372

Accumulation of (241)Am by suspended matter, diatoms and aquatic weeds of the Yenisei River.  

PubMed

In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating (241)Am from water. In our experiments large particles of seston (>8mum), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella formosa and Diatoma vulgare) was lower than by total seston. The concentration factors (CFs) of (241)Am for seston of the Yenisei River in our experiments were (2.8-6.9).10(5); for diatoms - (1.5-4.2).10(4). The CFs for aquatic plant Elodea canadensis were within the same order of magnitude as those for diatoms. Activity concentration and CFs of (241)Am were nearly the same in experiments under dark and light conditions. This is indicative of an energy independent mechanism of americium uptake from the water by diatoms and submerged macrophytes. PMID:19879676

Zotina, T A; Bolsunovsky, A Ya; Bondareva, L G

2010-02-01

373

Genome-wide identification of regulatory elements and reconstruction of gene regulatory networks of the green alga Chlamydomonas reinhardtii under carbon deprivation.  

PubMed

The unicellular green alga Chlamydomonas reinhardtii is a long-established model organism for studies on photosynthesis and carbon metabolism-related physiology. Under conditions of air-level carbon dioxide concentration [CO2], a carbon concentrating mechanism (CCM) is induced to facilitate cellular carbon uptake. CCM increases the availability of carbon dioxide at the site of cellular carbon fixation. To improve our understanding of the transcriptional control of the CCM, we employed FAIRE-seq (formaldehyde-assisted Isolation of Regulatory Elements, followed by deep sequencing) to determine nucleosome-depleted chromatin regions of algal cells subjected to carbon deprivation. Our FAIRE data recapitulated the positions of known regulatory elements in the promoter of the periplasmic carbonic anhydrase (Cah1) gene, which is upregulated during CCM induction, and revealed new candidate regulatory elements at a genome-wide scale. In addition, time series expression patterns of 130 transcription factor (TF) and transcription regulator (TR) genes were obtained for cells cultured under photoautotrophic condition and subjected to a shift from high to low [CO2]. Groups of co-expressed genes were identified and a putative directed gene-regulatory network underlying the CCM was reconstructed from the gene expression data using the recently developed IOTA (inner composition alignment) method. Among the candidate regulatory genes, two members of the MYB-related TF family, Lcr1 (Low-CO 2 response regulator 1) and Lcr2 (Low-CO2 response regulator 2), may play an important role in down-regulating the expression of a particular set of TF and TR genes in response to low [CO2]. The results obtained provide new insights into the transcriptional control of the CCM and revealed more than 60 new candidate regulatory genes. Deep sequencing of nucleosome-depleted genomic regions indicated the presence of new, previously unknown regulatory elements in the C. reinhardtii genome. Our work can serve as a basis for future functional studies of transcriptional regulator genes and genomic regulatory elements in Chlamydomonas. PMID:24224019

Winck, Flavia Vischi; Vischi Winck, Flavia; Arvidsson, Samuel; Riańo-Pachón, Diego Mauricio; Hempel, Sabrina; Koseska, Aneta; Nikoloski, Zoran; Urbina Gomez, David Alejandro; Rupprecht, Jens; Mueller-Roeber, Bernd

2013-01-01

374

Genome-Wide Identification of Regulatory Elements and Reconstruction of Gene Regulatory Networks of the Green Alga Chlamydomonas reinhardtii under Carbon Deprivation  

PubMed Central

The unicellular green alga Chlamydomonas reinhardtii is a long-established model organism for studies on photosynthesis and carbon metabolism-related physiology. Under conditions of air-level carbon dioxide concentration [CO2], a carbon concentrating mechanism (CCM) is induced to facilitate cellular carbon uptake. CCM increases the availability of carbon dioxide at the site of cellular carbon fixation. To improve our understanding of the transcriptional control of the CCM, we employed FAIRE-seq (formaldehyde-assisted Isolation of Regulatory Elements, followed by deep sequencing) to determine nucleosome-depleted chromatin regions of algal cells subjected to carbon deprivation. Our FAIRE data recapitulated the positions of known regulatory elements in the promoter of the periplasmic carbonic anhydrase (Cah1) gene, which is upregulated during CCM induction, and revealed new candidate regulatory elements at a genome-wide scale. In addition, time series expression patterns of 130 transcription factor (TF) and transcription regulator (TR) genes were obtained for cells cultured under photoautotrophic condition and subjected to a shift from high to low [CO2]. Groups of co-expressed genes were identified and a putative directed gene-regulatory network underlying the CCM was reconstructed from the gene expression data using the recently developed IOTA (inner composition alignment) method. Among the candidate regulatory genes, two members of the MYB-related TF family, Lcr1 (Low-CO2 response regulator 1) and Lcr2 (Low-CO2 response regulator 2), may play an important role in down-regulating the expression of a particular set of TF and TR genes in response to low [CO2]. The results obtained provide new insights into the transcriptional control of the CCM and revealed more than 60 new candidate regulatory genes. Deep sequencing of nucleosome-depleted genomic regions indicated the presence of new, previously unknown regulatory elements in the C. reinhardtii genome. Our work can serve as a basis for future functional studies of transcriptional regulator genes and genomic regulatory elements in Chlamydomonas. PMID:24224019

Vischi Winck, Flavia; Arvidsson, Samuel; Riańo-Pachón, Diego Mauricio; Hempel, Sabrina; Koseska, Aneta; Nikoloski, Zoran; Urbina Gomez, David Alejandro; Rupprecht, Jens; Mueller-Roeber, Bernd

2013-01-01

375

Gille-STPA 35 1 Noxious Algae in Carlsbad  

E-print Network

Gille-STPA 35 1 Noxious Algae in Carlsbad Spanish explorers of this region came across a lagoon Woodfield Dubbed "killer algae," the alien seaweed Caulerpa taxifolia was discovered in June 2000. Caulerpa taxifolia is a green alga native to tropical waters that typically grows to small size

Gille, Sarah T.

376

Diatoms (50 Species)  

USGS Multimedia Gallery

A photomicrograph depicting the siliceous frustules of fifty species of diatoms arranged within a circular shape. The image has been inverted to white on black to bring out details. Diatoms form the base of many marine and aquatic foodchains and upon death, their glassy frustules form sediments know...

377

Diatomic Spectral Database  

National Institute of Standards and Technology Data Gateway

SRD 114 Diatomic Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 121 diatomic molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty, and reference are given for each transition reported.

378

[Accumulation of polycyclic arenes in Baltic Sea algae].  

PubMed

The paper presents data on the level of benzo(a)pyrene (BP) and some other polycyclic arenes in alga and phanerogam specimens from different gulfs of the Baltic Sea. Algae were shown to absorb BP from sea water. The mean concentration of BP in sea water was under 0.004 microgram/1, while in algae it ranged 0.1-21.2 micrograms/kg dry weight. Algae accumulate BP to a higher degree than phanerogams. The highest concentrations of BP were found in algae Enteromorpha while the lowest ones in Furcellaria. In annual green algae, BP level was higher in autumn, i. e. at the end of vegetation period, than in spring. Brown algae Fucus vesiculosus is recommended for monitoring polycyclic arene pollution in the area from Vormsi Island to Käsmu and green algae Cladophora or Enteromorpha in the eastern part of the Finnish Gulf. PMID:4060672

Veldre, I A; Itra, A R; Paal'me, L P; Kukk, Kh A

1985-01-01

379

The seasonal growth and succession of plankton algae in the White Nile  

Microsoft Academic Search

A description is given of the seasonal growth and succession, over five years, of plank- tonic algae in a region of the White Nile affected by a reservoir. Dense populations develop during the period of water storage, and are dominated by the diatom illelosira granulata and the blucgrcen alga Anabaena jlos aquae var. intermedia f. spiroides. The sequence of their

G. A. PROWE; J. F. TALLING

1958-01-01

380

The distribution and abundance of algae in saline lakes of Saskatchewan, Canada  

Microsoft Academic Search

Collections of algae, mainly planktonic, were made from 41 saline lakes in southern Saskatchewan ranging in salinity from 3.2 to 428 g l-1. Algae in 7 phyla, 8 classes, 42 families, 91 genera and 212 species and varieties were identified. Fourteen species were restricted to hypersaline (50 g l-1) waters and eleven of these were diatoms. In general, species diversity

U. T-heodore Hammer; Jennifer Shamessl; Robert C. Haynes

1983-01-01

381

FRESHWATER ALGAE OF RAE LAKES BASIN, KINGS CANYON NATIONAL PARK (CALIFORNIA)  

EPA Science Inventory

This report illustrates and characterizes algae (exclusive of diatoms) found in Kings Canyon National Park, California and describes their distribution among the Rae Lakes within. It is the first taxonomic study of the freshwater algae for the southern Sierra Nevada and the most ...

382

Molecular identification of sequestered diatom chloroplasts and kleptoplastidy in foraminifera.  

PubMed

Kleptoplastidy is the ability of heterotrophic organisms to preserve chloroplasts of algal preys they eat and partially digest. As the sequestered chloroplasts stay functional for months, the "host" becomes photosynthetically active. Although remaining a marginal process, kleptoplastidy was observed in different protist lineages, including foraminifera. Previous studies showed at least eight species of the foraminiferal genera Haynesina and Elphidium grazing on diatoms and husbanding their chloroplasts. In order to characterize more precisely the origin of kleptochloroplasts in these genera, we obtained 1027 chloroplastic 16S rDNA sequences from 13 specimens of two Haynesina and five Elphidium species. We identified the foraminiferal kleptochloroplasts using a reference phylogeny made of 87 chloroplastic sequences of known species of diatoms and brown algae. All the analyzed specimens were performing kleptoplastidy and according to our phylogenetic analyses they seem to retain exclusively chloroplasts of diatom origin. There is no apparent specificity for the type of diatom from which chloroplasts originated, however some foraminiferal species seem to accept a wider range of diatoms than others. Possibly the diversity of kleptochloroplasts depends on the type of diatoms the foraminiferans feed on. PMID:21130034

Pillet, Loďc; de Vargas, Colomban; Pawlowski, Jan

2011-07-01

383

Photoautotrophic-heterotrophic biofilm communities: a laboratory incubator designed for growing axenic diatoms and bacteria in defined mixed-species biofilms.  

PubMed

Biofilm communities in the euphotic zone of aquatic habitats comprise photoautotrophic microorganisms, such as diatoms, green algae and cyanobacteria, which produce the organic carbon that fuels the life of a heterotrophic contingent of microorganisms, mostly bacteria. Such photoautotrophic-heterotrophic mixed-species biofilms have received little attention in biofilm research due to a lack of suitable pure-culture laboratory model systems. However, they offer important insight into microbial population dynamics and community interactions during a biofilm-developmental process that shapes highly structured, extremely well-adapted microbial landscapes. Here, we report on the development of a sterile incubation chamber for growing and monitoring axenic phototrophic biofilms, i.e. a sterilizable, illuminated, continuous-flow system for a routine work with pure cultures. The system has been designed to simulate the growth conditions in the shallow, littoral zone of aquatic habitats (horizontal surface, submerged in water, illuminated, aerated). Additional features of the concept include automated photometrical monitoring of biofilm density (as biofilm turbidity), analysis via confocal microscopy, direct harvesting of cells, and options to control illumination, flow velocity, and composition of culture fluid. The application of the system was demonstrated in growth experiments using axenic diatom biofilms, or axenic diatom biofilms co-cultivated with different bacterial strains isolated from epilithic biofilms of an oligotrophic freshwater lake. PMID:23757240

Buhmann, Matthias; Kroth, Peter G; Schleheck, David

2012-02-01

384

A comparative study: Assessment of the antioxidant system in the invasive green alga Caulerpa racemosa and some macrophytes from the Mediterranean  

Microsoft Academic Search

Reactive oxygen species (ROS) are of great importance in plant metabolism. However, uncontrolled activation of ROS might have deleterious effects in cells. Eleven Mediterranean countries are still under threat of an introduced taxon of Caulerpa racemosa var. cylindracea. In the present study, it has been aimed to compare the antioxidant status of this highly invasive alga with some Mediterranean macrophytes

Levent Cavas; Kadir Yurdakoc

2005-01-01

385

Photosynthetic and growth responses of three freshwater algae to phosphorus limitation and daylength  

E-print Network

Photosynthetic and growth responses of three freshwater algae to phosphorus limitation., green alga Sphaerocystis schroeteri and cyanobacterium Phormidium luridum, were grown under contrasting of the green alga S. schroeteri decreased the most (ca. sixfold) under P limitation compared with the other two

Bossard, Peter

386

428 BIOCHIMICAET BIOPHYSICAACTA pH CONTROL OF THE CHLOROPHYLL a FLUORESCENCE IN ALGAE  

E-print Network

428 BIOCHIMICAET BIOPHYSICAACTA BBA 46126 pH CONTROL OF THE CHLOROPHYLL a FLUORESCENCE IN ALGAE on the "slow" (min) time course of Chlorophyll a fluorescence yield in the green alga Chlorella pyrenoidosa and in the blue-green alga Anacystis nidulans. In Chlorella, the decay of fluorescence yield, in the I- to 5-rain

Govindjee

387

The development of artificial media for marine algae  

Microsoft Academic Search

The culturing of marine algae has proceeded slowly since MIQV~L (1890 93) succeeded in growing a few diatoms in the laboratory. Until recently most media were composed of sea water or sea water-like artificial solutions which are prone to precipitate because of the presence of several salts in concentration near saturation. In order to avoid precipitates such media must be

L. Provasoli; J. J. A. McLaughlin; M. R. Droop

1957-01-01

388

Photosynthetic energy conversion in the diatom Phaeodactylum tricornutum  

Microsoft Academic Search

Isothermal microcalorimetry can be used to investigate the photosynthetic energy conversion of autotrophic organisms. In this\\u000a study, for the first time a diatom alga was used to compare the calorimetrically measured heat flux with measurements of the\\u000a photosynthetic performance by oxygen evolution and pulse-amplitude modulated fluorescence. The presented experimental setup\\u000a proved suitable to compare calorimetric data with those of conventional

Steffen Oroszi; Torsten Jakob; Christian Wilhelm; Hauke Harms; Thomas Maskow

2011-01-01

389

Configurations of polyunsaturated sesterterpenoids from the diatom, Haslea ostrearia.  

PubMed

The partial configurations of C25 isoprenoid alkenes isolated from the diatom Haslea ostrearia Gaillon (Simonsen) have been established. A combination of NMR spectroscopy studies of the alkenes with chiral shift reagents in conjunction with soluble silver beta-diketonate complexes and enantioselective gas chromatography of oxidation products of the alkenes was used. Unexpected differences in highly branched isoprenoid isomer configurations were observed between different laboratory cultures of the alga. PMID:10724188

Johns, L; Belt, S; Lewis, C A; Rowland, S; Massé, G; Robert, J M; König, W A

2000-03-01

390

Do red and green make brown?: perspectives on plastid acquisitions within chromalveolates.  

PubMed

The chromalveolate "supergroup" is of key interest in contemporary phycology, as it contains the overwhelming majority of extant algal species, including several phyla of key importance to oceanic net primary productivity such as diatoms, kelps, and dinoflagellates. There is also intense current interest in the exploitation of these algae for industrial purposes, such as biodiesel production. However, the evolution of the constituent species, and in particular the origin and radiation of the chloroplast genomes, remains poorly understood. In this review, we discuss current theories of the origins of the extant red alga-derived chloroplast lineages in the chromalveolates and the potential ramifications of the recent discovery of large numbers of green algal genes in chromalveolate genomes. We consider that the best explanation for this is that chromalveolates historically possessed a cryptic green algal endosymbiont that was subsequently replaced by a red algal chloroplast. We consider how changing selective pressures acting on ancient chromalveolate lineages may have selectively favored the serial endosymbioses of green and red algae and whether a complex endosymbiotic history facilitated the rise of chromalveolates to their current position of ecological prominence. PMID:21622904

Dorrell, Richard G; Smith, Alison G

2011-07-01

391

Do Red and Green Make Brown?: Perspectives on Plastid Acquisitions within Chromalveolates ?  

PubMed Central

The chromalveolate “supergroup” is of key interest in contemporary phycology, as it contains the overwhelming majority of extant algal species, including several phyla of key importance to oceanic net primary productivity such as diatoms, kelps, and dinoflagellates. There is also intense current interest in the exploitation of these algae for industrial purposes, such as biodiesel production. However, the evolution of the constituent species, and in particular the origin and radiation of the chloroplast genomes, remains poorly understood. In this review, we discuss current theories of the origins of the extant red alga-derived chloroplast lineages in the chromalveolates and the potential ramifications of the recent discovery of large numbers of green algal genes in chromalveolate genomes. We consider that the best explanation for this is that chromalveolates historically possessed a cryptic green algal endosymbiont that was subsequently replaced by a red algal chloroplast. We consider how changing selective pressures acting on ancient chromalveolate lineages may have selectively favored the serial endosymbioses of green and red algae and whether a complex endosymbiotic history facilitated the rise of chromalveolates to their current position of ecological prominence. PMID:21622904

Dorrell, Richard G.; Smith, Alison G.

2011-01-01

392

Evaluation of higher plant virus resistance genes in the green alga, Chlorella variabilis NC64A, during the early phase of infection with Paramecium bursaria chlorella virus-1  

PubMed Central

With growing industrial interest in algae plus their critical roles in aquatic systems, the need to understand the effects of algal pathogens is increasing. We examined a model algal host–virus system, Chlorella variabilis NC64A and virus, PBCV-1. C. variabilis encodes 375 homologs to genes involved in RNA silencing and in response to virus infection in higher plants. Illumina RNA-Seq data showed that 325 of these homologs were expressed in healthy and early PBCV-1 infected (?60 min) cells. For each of the RNA silencing genes to which homologs were found, mRNA transcripts were detected in healthy and infected cells. C. variabilis, like higher plants, may employ certain RNA silencing pathways to defend itself against virus infection. To our knowledge this is the first examination of RNA silencing genes in algae beyond core proteins, and the first analysis of their transcription during virus infection. PMID:23701839

Rowe, Janet M.; Dunigan, David D.; Blanc, Guillaume; Gurnon, James R.; Xia, Yuannan; Van Etten, James L.

2014-01-01

393

Changes in the pigment patterns and the photosynthetic activity during a light-induced cell cycle of the green alga Scenedesmus armatus  

Microsoft Academic Search

The photosynthetic oxygen evolution as well as the chlorophyll and carotenoid patterns were studied during the light phase (14 h) of the Scenedesmus armatus cell cycle. The alga was synchronised by the light\\/dark regime (14\\/10 h). In this publication, the term “cell cycle” refers to this period of light only. The oxygen evolution measured by a Clark-type electrode and expressed

Zbigniew Tukaj; Krystyna Matusiak-Mikulin; Justyna Lewandowska; Janusz Szurkowski

2003-01-01

394

XET Activity is Found Near Sites of Growth and Cell Elongation in Bryophytes and Some Green Algae: New Insights into the Evolution of Primary Cell Wall Elongation  

Microsoft Academic Search

† Background and Aims In angiosperms xyloglucan endotransglucosylase (XET)\\/hydrolase (XTH) is involved in reorganization of the cell wall during growth and development. The location of oligo-xyloglucan transglucosyla- tion activity and the presence of XTH expressed sequence tags (ESTs) in the earliest diverging extant plants, i.e. in bryophytes and algae, down to the Phaeophyta was examined. The results provide information on

VICKY S. T. VAN SANDT; HERMAN STIEPERAERE; Y VES GUISEZ; JEAN-PIERRE VERBELEN; KRIS VISSENBERG

2007-01-01

395

Amino acid compositon and microbial contamination of spirulina maxima, a blue-green alga, grown on the effluent of different fermented animal wastes  

SciTech Connect

The nutrient compositions of various fermented manures were compared. Large differences in the mineral concentration were observed. There were no important differences among the amino acid composition of S. spirulina grown on the different nutrient media. All were low in methionine, but were rich in glutamic acid, aspartic acid, arginine, and leucine. The crude protein content was 71.8-60.1%. Considerable contamination of the waste-grown algae with yeast, fungi, and sporogenous bacteria was experienced.

Wu, J.F.; Pond, W.G.

1981-01-01

396

Multiple receptor-like kinase cDNAs from liverwort Marchantia polymorpha and two charophycean green algae, Closterium ehrenbergii and Nitella axillaris: Extensive gene duplications and gene shufflings in the early evolution of streptophytes.  

PubMed

Plant receptor-like kinases (RLKs) comprise a large family with more than several hundred members in vascular plants. The RLK family is thought to have diverged specifically in the plant kingdom, and no family member has been identified in other lineages except for animals and Plasmodium, both of which have RLK related families of small size. To know the time of divergence of RLK family members by gene duplications and domain shufflings, comprehensive isolations of RLK cDNAs were performed from a nonvascular plant, liverwort Marchantia polymorpha and two charophycean green algae, Closterium ehrenbergii, and Nitella axillaris, thought to be the closest relatives to land plants. We obtained twenty-nine, fourteen, and thirteen RLK related cDNAs from M. polymorpha, C. ehrenbergii, and N. axillaris, respectively. The amino acid sequences of these RLKs were compared with those of vascular plants, and phylogenetic trees were inferred by GAMT, a genetic algorithm-based maximum likelihood (ML) method that outputs multiple trees, together with best one. The inferred ML trees revealed ancient gene duplications generating subfamilies with different domain organizations, which occurred extensively at least before the divergence of vascular and nonvascular plants. Rather it remains possible that the extensive gene duplications occurred during the early evolution of streptophytes. Multicellular-specific somatic embryogenesis receptor kinase (SERK) involved in somatic embryogenesis was found in a unicellular alga C. ehrenbergii, suggesting the evolution of SERK by gene recruitment of a unicellular gene. PMID:17698300

Sasaki, Go; Katoh, Kazutaka; Hirose, Nozomi; Suga, Hiroshi; Kuma, Kei-ichi; Miyata, Takashi; Su, Zhi-Hui

2007-10-15

397

Star-shaped polymers of bio-inspired algae core and poly(acrylamide) and poly(acrylic acid) as arms in dissolution of silica/silicate.  

PubMed

Silica, in natural waters (due to weathering of rocks) decreases system performance in water processing industry due to scaling. In view of that, the present work involves the synthesis of novel green star shaped additives of algae core (a bio-inspired material as diatom maintains silicic acid equilibrium in sea water) as silica polymerization inhibitors. Star shaped materials with bio-inspired core and poly(acrylamide) [poly(AAm)] and poly(acrylic acid) [poly(AAc)] arms were synthesized by economical green approach. The proficiency was evaluated in 'mini lab' scale for the synthesized APAAm (Algae-g-poly(AAm)) and APAAc (Algae-g-poly(AAc)) dendrimers (star shaped) in colloidal silica mitigation/inhibition at 35 °C and 55 °C. Synthesized dendrimers were equally proficient in silica inhibition at 12 h and maintains ?450 ppm soluble silica. However, APAAm dendrimers of generation 0 confirmed better results (?300 ppm) in contrast to APAAc dendrimers in silica inhibition at 55 °C. Additionally, dendrimers also worked as a nucleator for heterogeneous polymerization to inhibit silica homo-polymerization. APAAm dendrimer test set showed no silica deposit for more than 10 days of inhibition. EDX characterization results support nucleator mechanism with Si content of 6.97%-10.98% by weight in silica deposits (SiO2-APAAm dendrimer composites). PMID:24681378

Chauhan, Kalpana; Patiyal, Priyanka; Chauhan, Ghanshyam S; Sharma, Praveen

2014-06-01

398

Effects of temperature on the production of hydrogen peroxide and volatile halocarbons by brackish-water algae.  

PubMed

Marine algae produce volatile halocarbons, which have an ozone-depleting potential. The formation of these compounds is thought to be related to oxidative stress, involving H2O2 and algal peroxidases. In our study we found strong correlations between the releases of H2O2 and brominated and some iodinated compounds to the seawater medium, but no such correlation was found for CHCl3, suggesting the involvement of other formation mechanisms as well. Little is known about the effects of environmental factors on the production of volatile halocarbons by algae and in the present study we focused on the influence of temperature. Algae were sampled in an area of the brackish Baltic Sea that receives thermal discharge, allowing us to collect specimens of the same species that were adapted to different field temperature regimes. We exposed six algal species (the diatom Pleurosira laevis, the brown alga Fucus vesiculosus and four filamentous green algae, Cladophora glomerata, Enteromorpha ahlneriana, E. flexuosa and E. intestinalis) to temperature changes of 0-11 degrees C under high irradiation to invoke oxidative stress. The production rates, as well as the quantitative composition of 16 volatile halocarbons, were strongly species-dependent and different types of responses to temperature were recorded. However, no response patterns to temperature change were found that were consistent for all species or for all halocarbons. We conclude that the production of certain halocarbons may increase with temperature in certain algal species, but that the amount and composition of the volatile halocarbons released by algal communities are probably more affected by temperature-associated species shifts. These results may have implications for climatic change scenarios. PMID:13679095

Abrahamsson, Katarina; Choo, Kyung Sil; Pedersén, Marianne; Johansson, Gustav; Snoeijs, Pauli

2003-10-01

399

Effect of the expression and knockdown of citrate synthase gene on carbon flux during triacylglycerol biosynthesis by green algae Chlamydomonas reinhardtii  

PubMed Central

Background The regulation of lipid biosynthesis is essential in photosynthetic eukaryotic cells. This regulation occurs during the direct synthesis of fatty acids and triacylglycerols (TAGs), as well as during other controlling processes in the main carbon metabolic pathway. Results In this study, the mRNA levels of Chlamydomonas citrate synthase (CrCIS) were found to decrease under nitrogen-limited conditions, which suggests suppressed gene expression. Gene silencing by RNA interference (RNAi) was conducted to determine whether CrCIS suppression affected the carbon flux in TAG biosynthesis. Results showed that the TAG level increased by 169.5%, whereas the CrCIS activities in the corresponding transgenic algae decreased by 16.7% to 37.7%. Moreover, the decrease in CrCIS expression led to the increased expression of TAG biosynthesis-related genes, such as acyl-CoA:diacylglycerol acyltransferase and phosphatidate phosphatase. Conversely, overexpression of CrCIS gene decreased the TAG level by 45% but increased CrCIS activity by 209% to 266% in transgenic algae. Conclusions The regulation of CrCIS gene can indirectly control the lipid content of algal cells. Our findings propose that increasing oil by suppressing CrCIS expression in microalgae is feasible. PMID:24373252

2013-01-01

400

Depth-related changes in benthic diatom assemblages of a maritime Antarctic lake  

Microsoft Academic Search

The epiphytic diatoms of filamentous matforming algae in Sombre Lake, Signy Island, South Orkneys, Antarctica were examined in a field study from January to March 1987. Results reveal 1) a shallow shelf assemblage, dominated by Fragilaria spp, with high percentages of empty frustules, and low numbers of viable cells and, 2) a mid-depth zone containing the most luxuriant epiphytic growth

Deborah R. Oppenheim; J. Cynan Ellis-Evans

1989-01-01

401

Project EARTH-11-RR2: Co-evolution of iodine antioxidant mechanism in marine algae and Earth-surface  

E-print Network

Project EARTH-11-RR2: Co-evolution of iodine antioxidant mechanism in marine algae and Earth algae (yet they are lacking in green algae) ­ but the phylogenetic distribution of iodine accumulation haloperoxidases. The first appearance and important divergence of brown algae occurred within the last 200 myr

Henderson, Gideon

402

Fossil diatoms and neogene paleolimnology  

USGS Publications Warehouse

Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the detailed descriptions of fossil diatoms will provide the basis for making more accurate correlations and identifications, and the micromorphological detail for speculations about evolutionary relationships. ?? 1988.

Platt, Bradbury J.

1988-01-01

403

Assembly of the Light-Harvesting Chlorophyll Antenna in the Green Alga Chlamydomonas reinhardtii Requires Expression of the TLA2-CpFTSY Gene1[C][W][OA  

PubMed Central

The truncated light-harvesting antenna2 (tla2) mutant of Chlamydomonas reinhardtii showed a lighter-green phenotype, had a lower chlorophyll (Chl) per-cell content, and higher Chl a/b ratio than corresponding wild-type strains. Physiological analyses revealed a higher intensity for the saturation of photosynthesis and greater Pmax values in the tla2 mutant than in the wild type. Biochemical analyses showed that the tla2 strain was deficient in the Chl a-b light-harvesting complex, and had a Chl antenna size of the photosystems that was only about 65% of that in the wild type. Molecular and genetic analyses showed a single plasmid insertion in the tla2 strain, causing a chromosomal DNA rearrangement and deletion/disruption of five nuclear genes. The TLA2 gene, causing the tla2 phenotype, was cloned by mapping the insertion site and upon complementation with each of the genes that were deleted. Successful complementation was achieved with the C. reinhardtii TLA2-CpFTSY gene, whose occurrence and function in green microalgae has not hitherto been investigated. Functional analysis showed that the nuclear-encoded and chloroplast-localized CrCpFTSY protein specifically operates in the assembly of the peripheral components of the Chl a-b light-harvesting antenna. In higher plants, a cpftsy null mutation inhibits assembly of both the light-harvesting complex and photosystem complexes, thus resulting in a seedling-lethal phenotype. The work shows that cpftsy deletion in green algae, but not in higher plants, can be employed to generate tla mutants. The latter exhibit improved solar energy conversion efficiency and photosynthetic productivity under mass culture and bright sunlight conditions. PMID:22114096

Kirst, Henning; García-Cerdán, Jose Gines; Zurbriggen, Andreas; Melis, Anastasios

2012-01-01

404

Algae to Bio-Crude in Less Than 60 Minutes  

ScienceCinema

Engineers have created a chemical process that produces useful crude oil just minutes after engineers pour in harvested algae -- a verdant green paste with the consistency of pea soup. The PNNL team combined several chemical steps into one continuous process that starts with an algae slurry that contains as much as 80 to 90 percent water. Most current processes require the algae to be dried -- an expensive process that takes a lot of energy. The research has been licensed by Genifuel Corp.

Elliott, Doug

2014-06-02

405

Algae Biodiesel: Commercialization  

E-print Network

Algae Biodiesel: A Path to Commercialization Algae Biodiesel: A Path to Commercialization Center conservation and biomonitoring · Algae biodiesel is largest CEHMM project #12;Project Overview: The Missing replace petroleum #12;Project Overview: Local Resources for Algae Biodiesel Project Overview: Local

Tullos, Desiree

406

Sulfated polysaccharides as bioactive agents from marine algae.  

PubMed

Recently, much attention has been paid by consumers toward natural bioactive compounds as functional ingredients in nutraceuticals. Marine algae are considered as valuable sources of structurally diverse bioactive compounds. Marine algae are rich in sulfated polysaccharides (SPs) such as carrageenans in red algae, fucoidans in brown algae and ulvans in green algae. These SPs exhibit many health beneficial nutraceutical effects such as antioxidant, anti-allergic, anti-human immunodeficiency virus, anticancer and anticoagulant activities. Therefore, marine algae derived SPs have great potential to be further developed as medicinal food products or nutraceuticals in the food industry. This contribution presents an overview of nutraceutical effects and potential health benefits of SPs derived from marine algae. PMID:23994790

Ngo, Dai-Hung; Kim, Se-Kwon

2013-11-01

407

Video micrography of algae photomovement and vectorial method of biomonitoring  

NASA Astrophysics Data System (ADS)

The simultaneous recording of several photomovement parameters of algae as test-functions during biomonitoring is proposed. Green alga Dunaliella viridis Teod. was used as the test- object for the estimation of different heavy metals. The quantitative changes of photomovement parameters as a criterion of toxicity were determined by means of the vectorial method of biomonitoring.

Posudin, Yuri I.; Massjuk, N. P.; Lilitskaya, G. G.

1996-01-01

408

Competition between the photosynthetic and the (chloro)respiratory electron transport chains in cyanobacteria, green algae and higher plants. Effect of heat stress  

Microsoft Academic Search

By measuring the effect of cyanide on the flash-induced redox reactions of the cytochrome (cyt) b\\u000a 6\\/f complex we carried out a comparative study in order to characterize the interaction between the photosynthetic and the respiratory\\u000a electron transport systems in cyanobacterial (Synechococcus sp. PCC 6301) and green algal (Chlamydomonas reinhardtii) cells, and in tobacco (Nicotiana tabacum L. cv. Petit Havana

F. Lajkó; A. Kadioglu; G. Borbély; G. Garab

1997-01-01

409

Colourful Cultures: Classroom Experiments with the Unicellular Alga Haematococcus pluvialis.  

ERIC Educational Resources Information Center

Describes an investigation into the photosynthetic potential of the different developmental stages of the green unicellular alga Haematococcus pluvialis. Reviews the biotechnological applications of astaxanthin, the red pigment which can be extracted from Haematococcus pluvialis. (Author/MM)

Delpech, Roger

2001-01-01

410

Identity and physiology of a new psychrophilic eukaryotic green alga, Chlorella sp., strain BI, isolated from a transitory pond near Bratina Island, Antarctica  

USGS Publications Warehouse

Permanently low temperature environments are one of the most abundant microbial habitats on earth. As in most ecosystems, photosynthetic organisms drive primary production in low temperature food webs. Many of these phototrophic microorganisms are psychrophilic; however, functioning of the photosynthetic processes of these enigmatic psychrophiles (the 'photopsychrophiles') in cold environments is not well understood. Here we describe a new chlorophyte isolated from a low temperature pond, on the Ross Ice Shelf near Bratina Island, Antarctica. Phylogenetic and morphological analyses place this strain in the Chlorella clade, and we have named this new chlorophyte Chlorella BI. Chlorella BI is a psychrophilic species, exhibiting optimum temperature for growth at around 10??C. However, psychrophily in the Antarctic Chlorella was not linked to high levels of membrane-associated poly-unsaturated fatty acids. Unlike the model Antarctic lake alga, Chlamydomonas raudensis UWO241, Chlorella BI has retained the ability for dynamic short term adjustment of light energy distribution between photosystem II (PS II) and photosystem I (PS I). In addition, Chlorella BI can grow under a variety of trophic modes, including heterotrophic growth in the dark. Thus, this newly isolated photopsychrophile has retained a higher versatility in response to environmental change than other well studied cold-adapted chlorophytes. ?? 2008 Springer.

Morgan-Kiss, R. M.; Ivanov, A.G.; Modla, S.; Czymmek, K.; Huner, N.P.A.; Priscu, J.C.; Lisle, J.T.; Hanson, T.E.

2008-01-01

411

Life-Cycle and Genome of OtV5, a Large DNA Virus of the Pelagic Marine Unicellular Green Alga Ostreococcus tauri  

PubMed Central

Large DNA viruses are ubiquitous, infecting diverse organisms ranging from algae to man, and have probably evolved from an ancient common ancestor. In aquatic environments, such algal viruses control blooms and shape the evolution of biodiversity in phytoplankton, but little is known about their biological functions. We show that Ostreococcus tauri, the smallest known marine photosynthetic eukaryote, whose genome is completely characterized, is a host for large DNA viruses, and present an analysis of the life-cycle and 186,234 bp long linear genome of OtV5. OtV5 is a lytic phycodnavirus which unexpectedly does not degrade its host chromosomes before the host cell bursts. Analysis of its complete genome sequence confirmed that it lacks expected site-specific endonucleases, and revealed the presence of 16 genes whose predicted functions are novel to this group of viruses. OtV5 carries at least one predicted gene whose protein closely resembles its host counterpart and several other host-like sequences, suggesting that horizontal gene transfers between host and viral genomes may occur frequently on an evolutionary scale. Fifty seven percent of the 268 predicted proteins present no similarities with any known protein in Genbank, underlining the wealth of undiscovered biological diversity present in oceanic viruses, which are estimated to harbour 200Mt of carbon. PMID:18509524

Derelle, Evelyne; Ferraz, Conchita; Escande, Marie-Line; Eychenié, Sophie; Cooke, Richard; Piganeau, Gwenaël; Desdevises, Yves; Bellec, Laure; Moreau, Hervé; Grimsley, Nigel

2008-01-01

412

Conversion of membrane lipid acyl groups to triacylglycerol and formation of lipid bodies upon nitrogen starvation in biofuel green algae Chlorella UTEX29.  

PubMed

Algal lipids are ideal biofuel sources. Our objective was to determine the contributors to triacylglycerol (TAG) accumulation and lipid body formation in Chlorella UTEX29 under nitrogen (N) deprivation. A fivefold increase in intracellular lipids following N starvation for 24 h confirmed the oleaginous characteristics of UTEX29. Ultrastructural studies revealed increased number of lipid bodies and decreased starch granules in N-starved cells compared to N-replete cells. Lipid bodies were observed as early as 3 h after N removal and plastids collapsed after 48 h of stress. Moreover, the identification of intracellular pyrenoids and differences in the expected nutritional requirements for Chlorella protothecoides (as UTEX29 is currently classified) led us to conduct a phylogenetic study using 18S and actin cDNA sequences. This indicated UTEX29 to be more phylogenetically related to Chlorella vulgaris. To investigate the fate of different lipids after N starvation, radiolabeling using ą?C-acetate was used. A significant decrease in ą?C-galactolipids and phospholipids matched the increase in ą?C-TAG starting at 3 h of N starvation, consistent with acyl groups from structural lipids as sources for TAG under N starvation. These results have important implications for the identification of key steps controlling oil accumulation in N-starved biofuel algae and demonstrate membrane recycling during lipid body formation. PMID:23928654

Goncalves, Elton C; Johnson, Jodie V; Rathinasabapathi, Bala

2013-11-01

413

The effects of crude and fuel oils on the growth, chlorophyll 'a' content and dry matter production of a green alga Scenedesmus quadricauda (Turp.) bréb.  

PubMed

The growth of Scenedesmus quadricauda algae in a batch culture was examined in the presence of crude oil and fuel oil, added to the cultivation medium in the form of a water-soluble fraction (WSF), water extract (WE) and oil-water dispersion (OWD). On applying various concentrations of oils, a decrease in the number of cells, dry matter and chlorophyll 'a' production, with respect to the cell population, was observed. The extent of this decrease depended on the kind and concentration of the soluble and dispersed hydrocarbon fractions and on the proportions in which these occurred in the culture medium. On the other hand, the water extracts of both oils stimulated dry mass and chlorophyll 'a' content with respect to a single cell. This effect was accompanied by increased size of the algal cells. The WSF, WE and OWD of fuel oil, prepared from 200, 50 and 1 cm(3) of oil per dm(3) of BBM medium, respectively, had a similar inhibitory effect, which points to the dominant role of oil dispersion in the reduction of algal growth. Chemical analysis of the water extracts of fuel oil revealed the presence of 35 hydrocarbons of various kinds, mainly n-alkanes and polycyclic aromatic hydrocarbons. PMID:15092718

Tukaj, Z

1987-01-01

414

Life-Cycle and Genome of OtV5, a Large DNA Virus of the Pelagic Marine Unicellular Green Alga Ostreococcus tauri  

E-print Network

Large DNA viruses are ubiquitous, infecting diverse organisms ranging from algae to man, and have probably evolved from an ancient common ancestor. In aquatic environments, such algal viruses control blooms and shape the evolution of biodiversity in phytoplankton, but little is known about their biological functions. We show that Ostreococcus tauri, the smallest known marine photosynthetic eukaryote, whose genome is completely characterized, is a host for large DNA viruses, and present an analysis of the life-cycle and 186,234 bp long linear genome of OtV5. OtV5 is a lytic phycodnavirus which unexpectedly does not degrade its host chromosomes before the host cell bursts. Analysis of its complete genome sequence confirmed that it lacks expected site-specific endonucleases, and revealed the presence of 16 genes whose predicted functions are novel to this group of viruses. OtV5 carries at least one predicted gene whose protein closely resembles its host counterpart and several other host-like sequences, suggesting that horizontal gene transfers between host and viral genomes may occur frequently on an evolutionary scale. Fifty seven percent of the 268 predicted proteins present no similarities with any known protein in Genbank, underlining the wealth of undiscovered biological diversity

Evelyne Derelle; Conchita Ferraz; Marie-line Esc; Sophie Eychenié; Richard Cooke; Yves Desdevises; Laure Bellec; Hervé Moreau; Nigel Grimsley

2008-01-01

415

Gene structure of a chlorophyll a/c-binding protein from a brown alga: presence of an intron and phylogenetic implications.  

PubMed

A Laminaria saccharina genomic library in the phage EMBL 4 was used to isolate and sequence a full-length gene encoding a fucoxanthin-chlorophyll a/c-binding protein. Contrary to diatom homologues, the coding sequence is interrupted by an intron of about 900 bp which is located in the middle of the transit peptide. The deduced amino acid sequence of the mature protein is very similar to those of related proteins from Macrocystis pyrifera (Laminariales) and, to a lesser extent, to those from diatoms and Chrysophyceae. Seven of the eight putative chlorophyll-binding amino acids determined in green plants are also present. Alignments of different sequences related to the light-harvesting proteins (LHC) demonstrate a structural similarity among the three transmembrane helices and suggest a unique ancestral helix preceded by two beta-turns. The beta-turns are conserved in front of the second helices of the chlorophyll a/c proteins more so than in chlorophyll a/b proteins. Phylogenetic trees generated from sequence data indicate that fucoxanthin-chlorophyll-binding proteins diverged prior to the separation of photosystem I and photosystem II LHC genes of green plants. Among the fucoxanthin-containing algae, LHC I or II families could not be distinguished at this time. PMID:8703093

Caron, L; Douady, D; Quinet-Szely, M; de Goër, S; Berkaloff, C

1996-09-01