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PubMed2006

The interactive effects of binary mixtures of three antifouling biocides and three heavy metals against the marine algae Chaetoceros gracilis.

Three of the most commonly used antifouling booster biocides that are usually combined with copper or copper compounds are Irgarol 1051, Diuron, and Zn pyrithione. This study represents an assessment of the interactive effects of the antifouling biocides combined with each other, and with three heavy metals (Cu, Cd, and Zn) in binary mixtures, on the marine algae Chaetoceros gracilis. Seventy-two hour growth inhibition tests were carried out, and the IC50 values of the chemicals were determined along with growth inhibition (%) for several concentrations. The joint effect of the binary mixtures of all the chemicals was assessed by using two models, concentration addition model and the model of probabilities. The following increasing order of toxicity was obtained: Cd < Zn < Cu < Diuron < Zn pyrithione < Irgarol 1051. The interactive effects of the organic chemicals combined with each other on the growth of Ch. gracilis were firmly synergistic. Irgarol 1051 combined with Cd performed synergistic effects, and Zn pyrithione with copper and cadmium action was strictly antagonistic, and the results of the two models were in agreement in almost all mixtures.

Cadmium↗
PubMed1993

Biosynthesis of vicinal dihydroxy fatty acids in the red alga Gracilariopsis lemaneiformis: identification of a sodium-dependent 12-lipoxygenase and a hydroperoxide isomerase.

Biosynthesis of the vicinal diol fatty acid (12R,13S)-dihydroxy-(5Z,8Z,10E,14Z)-eicosatetrae noic acid from arachidonic acid was studied in preparations of the red alga Gracilariopsis lemaneiformis. The transformation consisted of initial 12-lipoxygenase-catalyzed oxygenation of arachidonic acid into (12S)-hydroperoxy-(5Z,8Z,10E,14Z)-eicosatetraeno ic acid followed by hydroperoxide isomerase-catalyzed conversion of the hydroperoxide into (12R,13S)-dihydroxyeicosatetraenoic acid. Short time incubations and trapping experiments with glutathione peroxidase revealed that (12S)-hydroperoxyeicosatetraenoic acid existed as a free intermediate in the overall conversion. The 12-lipoxygenase was mainly present in the soluble fraction of homogenate of G. lemaneiformis. Further, gel filtration experiments showed that the soluble 12-lipoxygenase was a protein having a molecular weight of 84,000-89,000. The enzymatic activity of 12-lipoxygenase isolated by gel filtration was weak; however, addition of 0.8-1 M sodium chloride to such desalted enzyme increased the activity 20-fold. Experiments with different salts revealed that sodium ion was specifically responsible for the stimulatory effect. Hydroperoxide isomerase was about equally distributed between the high speed supernatant and particulate fractions. Gel filtration of hydroperoxide isomerase present in the soluble fraction showed two peaks of activity corresponding to proteins having molecular weights of 220,000 or greater, and 40,000-45,000. The stereochemical course of the biosynthesis of vicinal diol fatty acids was determined using stereospecifically deuterated 6,9,12-octadecatrienoic acids. The 12-lipoxygenase-catalyzed reaction consisted of antarafacial hydrogen removal and oxygen insertion, whereas the hydroperoxide isomerase catalyzed an intramolecular oxygenation which occurred with retention of the configuration of the carbon atom hydroxylated.

Arachidonate 12-Lipoxygenase↗
PubMed1996

Purification and properties of four phosphoenolpyruvate carboxylase isoforms from the green alga Selenastrum minutum: evidence that association of the 102-kDa catalytic subunit with unrelated polypeptides may modify the physical and kinetic properties of the enzyme.

Four isoforms of phosphoenolpyruvate carboxylase (PEPC1, PEPC2, PEPC3, PEPC4) have been purified from the green alga Selenastrum minutum. PEPC1 is a homotetramer with a subunit M(r) of 102 kDa. PEPC2, PEPC3, and PEPC4 have respective native M(r)S of approximately 984, 1186, and 1590 kDa. SDS/PAGE analysis revealed that the latter three isoforms contain polypeptides having M(r)S of 102, 73, 70, 65, and 61 kDa. Immunoblot analyses and CNBr cleavage patterns suggest that the 102-kDa polypeptide present in all four isoforms is the same PEPC catalytic subunit. Our data suggest that the three high M(r)S PEPC isoforms are heteromeric protein complexes consisting of the 102-kDa PEPC1 catalytic subunit and immunologically unrelated polypeptides. Attempts to measure other enzyme activities associated with the protein complexes gave negative results. However, PEPC1 had immunological, physical, and kinetic properties very different from those of the larger M(r) PEPC isoforms: (i) the anti-PEPC1 immune-serum was relatively inefficient for immunoprecipitating PEPC2, PEPC3, or PEPC4; (ii) immune-serum raised against a mixture of PEPC2, PEPC3, and PEPC4 had relatively weak immunoprecipitating activity toward PEPC1; (iii) PEPC1 was more heat sensitive than the other three isoforms; (iv) PEPC1 had a pH optimum of 9 versus 8.5 for the PEPC protein complexes; (v) the high Mr PEPCs had greater apparent affinity for phosphoenolpyruvate compared to PEPC1 and (vi) PEPC1 activity was far more sensitive to metabolite activators (Gln and dihydroxyacetone phosphate) and inhibitors (Asp, Glu, 2-oxoglutarate and malate). We conclude that the interaction of the PEPC catalytic subunit with unrelated polypeptides is responsible for the observed differences between PEPC1 and the high molecular mass isoforms. We propose that this interaction possibly regulates PEPC activity in vivo.

Chlorophyta↗
PubMed1999

A dye binding assay for the quantification of soluble and cell-bound acidic polysaccharides produced by red algae.

Polysaccharides produced in technical scale from red algae serve in a variety of industrial applications. Ruthenium red (RR) is a cytochemical stain which has been used to visualize these mostly acidic polysaccharides in light microscopy. The binding of RR to algal polysaccharides is highly dependent on the ionic strength of the surrounding medium. The dye is firmly bound at low ionic strength, but is released at increasing salt concentrations. These properties were exploited to develop a new method to quantify the amount of cell wall material synthesized by algal cells under different physiological conditions. Soluble or extracted polysaccharides are quantified by a dot-blot procedure with subsequent image analysis, while cell-bound polysaccharides are determined in situ by a dye-binding assay followed by photometry. In comparison to the current methods of quantification, the new assay is quick, reliable, and avoids extensive use of hazardous chemicals.

Calibration↗
PubMed2000

Use of high-resolution magic angle spinning nuclear magnetic resonance spectroscopy for in situ studies of low-molecular-mass compounds in red algae.

The use of high-resolution magic angle spinning NMR spectroscopy for in situ studies of low-molecular-mass compounds in red algae has been studied. The impact of different acquisition parameters on the resulting T(2)-filtered one-dimensional high-resolution magic angle spinning (1)H NMR spectra is described. The technique was used for in situ identification and quantification of some low-molecular-mass algal metabolites.

Magnetic Resonance Spectroscopy↗
PubMed1997

Ribulose-1,5-bisphosphate carboxylase/oxygenase from thermophilic red algae with a strong specificity for CO2 fixation.

Strongly carboxylase-specific ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) was found in Galdieria partita and Cyanidium caldarium (Cyanidiophyceae). The relative specificity, VcKo/VoKc, of Galdieria and Cyanidium RuBisCO was 238 and 222, respectively; 2.4 to 2.5-fold that of higher plant RuBisCOs. The apparent Km of RuBisCO from the thermophilic red algae for CO2 was 6 to 7 microM and the smallest of the values reported so far for other RuBisCOs. The pre-rhodophyte Porphiridium purpureum, which lives at moderate temperatures, had RuBisCO with the relative specificity value of 144. A large difference (5.2 kcal x mol(-1)) in the activation energies between the carboxylase and oxygenase activities in Galdieria RuBisCO was a cause of the strong specificity for the carboxylase activity.

Carbon Dioxide↗
PubMed1999

Cloning, expression of the psbU gene, and functional studies of the recombinant 12-kDa protein of photosystem II from a red alga Cyanidium caldarium.

The encoding extrinsic 12-kDa protein of oxygen-evolving PS II complex from a red alga, Cyanidium caldarium, was cloned and sequenced by means of PCR and a rapid amplification of cDNA ends (RACE) procedure. The gene encodes a putative polypeptide of 154 amino acids with a calculated molecular mass of 16,714 Da. The full sequence of the protein includes two characteristic transit peptides, one for transfer across the chloroplast envelope and another for targeting into the thylakoid lumen. This indicates that the protein is encoded in the nuclear genome. The mature protein consists of 93 amino acids with a calculated molecular mass of 10,513 Da. The cloned gene was successfully expressed in Escherichia coli and the resulting protein was purified, reconstituted to CaCl2-washed PS II complex together with the other extrinsic proteins of 33 and 20 kDa and cyt c-550. The recombinant 12-kDa protein bound completely with the PSII complex, which resulted in a restoration of oxygen evolution equal to the level achieved by binding of the native 12-kDa protein.

Amino Acid Sequence↗
PubMed1999

A new member of the leucyl aminopeptidase family purified and identified from a marine unicellular algae.

Leucyl aminopeptidase (LAP; EC 3.4.11.1) activity was purified from crude extracts of the marine unicellular algae Gonyaulax polyedra by a combination of hydrophobic interaction with phenyl sepharose, DEAE-cellulose, and mono-Q HR5/5 ion-exchange chromatography. The undenaturated protein has a molecular mass of about 110 kD and based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme appears to be composed of two possibly identical subunits of 55 kD. The identity of the protein was confirmed by a cross-reaction of the purified protein with an antibody raised against a commercial LAP. Biochemical characterization showed that the Gonyaulax enzyme was similar to most of the previously described LAPs. Gonyaulax LAP is a metallo-enzyme since EDTA and 1,10-phenathroline significantly inhibited activity. Addition of the metal ions Zn(2+), Cu(2+) inhibited 80% of LAP activity, suggesting they are not the natural cofactors of the enzyme. Other metals, such as Ca(2+), Co(2+), Mn(2+), or Mg(2+) (concentrations up to 4 mM), caused no alteration in the total activity of Gonyaulax LAP.

Animals↗
PubMed2000

The molecular structure of the fastest myosin from green algae, Chara.

Chara myosin in green algae, Chara corallina, is the fastest myosin of all those observed so far. To shed light on the molecular mechanism of this fast sliding, we determined the primary structure of Chara myosin heavy chain (hc). It has a motor domain, six IQ motifs for calmodulin binding, a coiled-coil structure to dimerize, and a globular tail. Chara myosin hc is very similar to some plant myosins and has been predicted to belong to the class XI. Short loop 1 and loop 2 may account for the characteristics of mechanochemical properties of Chara myosin.

Amino Acid Sequence↗
PubMed1994

Elongation factor 1 alpha is a component of the subcortical actin bundles of characean algae.

Antibodies to elongation factor 1 alpha (EF1 alpha), a known 50 kDa actin-bundling protein in Dictyostelium, identified a protein in a whole cell extract of the characean alga Nitella pseudoflabellata that had an apparent molecular weight of 51 kDa. Indirect immunofluorescence microscopy revealed labelling by the EF1 alpha antibodies of the subcortical actin bundles, even after the motile organelles of the endoplasm were removed by perfusion with ATP-containing solutions.

Actins↗
PubMed1996

Partial characterization of a putative 110 kDa myosin from the green alga Chara corallina by in vitro binding of fluorescent F-actin.

Using the binding of heterologous, rhodamine phalloidin-labelled F-actin in vitro, two F-actin binding proteins were identified in protein extracts from the green alga Chara corallina after fractionation by anion exchange chromatography. The first protein, a putative myosin, released laterally bound F-actin at ATP-concentrations as low as 1 microM; equivalent concentrations of ADP were not effective. Binding of F-actin was inhibited by the sulfhydryl-alkylating agent N-ethylmaleimide (NEM). Binding of F-actin was also abolished by a monoclonal anti-myosin (J14) previously used for immunodetection and immunolocalization in internodal cells (Grolig et al., 1988, Eur J Cell Biol 47: 22-31). Immunoblotting with J14 detected a 110 kDa polypeptide only in those protein fractions that had revealed ATP-sensitive binding of F-actin. The putative myosin bound with mediocre affinity to immobilized calmodulin and free Ca(2+)-concentration made no difference to this binding affinity. In contrast to the putative myosin, the second, less abundant protein revealed ATP-insensitive and end-wise binding to the microfilament and was not recognized by the anti-myosin antibody.

Actins↗
PubMed2002

Kinesin-like proteins are involved in postmitotic nuclear migration of the unicellular green alga Micrasterias denticulata.

The unicellular green alga Micrasterias denticulata performs a two-directional postmitotic nuclear migration during development, a passive migration into the growing semicell, and a microtubule mediated backward migration towards the cell centre. The present study provides first evidence for force generation by motor proteins of the kinesin family in this process. The new kinesin specific inhibitor adociasulfate-2 causes abnormal nuclear displacement at 18 microM. AMP-PNP, a non hydrolyseable ATP analogue or the general ATPase inhibitors calyculin A and sodium orthovanadate also disturb nuclear migration. In addition kinesin-like proteins are detected by means of immunoblotting using antibodies against brain kinesin, plant derived antibodies to kinesin-like proteins and a calmodulin binding kinesin-like protein. Immunoelectron microscopy suggests a correlation of conventional kinesin-like proteins, but not of the calmodulin binding kinesin-like protein to the microtubule apparatus associated with the migrating nucleus.

Adenosine Triphosphatases↗
PubMed1996

Effect of organotin compounds on the growth of the freshwater alga Scenedesmus quadricauda.

Organotin compounds (OTCs) are extensively used in a variety of industrial processes and their increasing discharge into the environment is a topic of current concern. Many OTCs are toxic to various organisms and they are used to a limited but significant extent as biocidal agents in agriculture and technology. The concentration and form in which tin (Sn) is present in the environment determines its toxicological effects. The present study was conducted to determine the inhibitory effect of 12 OTCs [A, dibutyl tin bis-N,N-diethyldithiocarbamate; B, dimethyltin bis(N, N-diethyldithiocarbamate); C, triphenyltin chloride; D, triphenyltin acetate; E, triphenyltin N,N-diethyldithiocarbamate; F, tribenzyltin bis(N,N-diethyldithiocarbamate); G, tribenzyltin chloride; H, bis (tributyltin)-3,4,5,6-tetrachlor phthalate; I, tributyltin sulfaminate; J, tributyltin N,N-diethyldithiocarbamate; K, tributyltin naphthenate; and L, tributyltin oxide (TBTO)] in four concentrations (0.001, 0.01, 0.1, and 1.0 mg/liter) on the growth of freshwater alga Scenedesmus quadricauda under standardized conditions. The inhibitory effect of OTCs after 12 days cultivation in percentages for each concentration used was determined and individual growth curves of S. quadricauda for tested concentrations of OTCs and for control were plotted. On the basis of the percentage of control growth the rank order of inhibition after 12 days application of OTCs in concentration 1.0 mg/liter was made: L = H = F = C > E > D > J = K > I > G > A > B. From this rank order, it is evident that the least inhibitive effects on algal growth were from the diorganotin compounds A and B, especially compound B with a methyl group in the n-alkyl chain. The most toxic was compound L (TBTO) with a butyl group in side chain.

Dose-Response Relationship, Drug↗
PubMed1998

Evaluation of a high-hardness COMBO medium and frozen algae for Daphnia magna.

A new high-hardness (H-H) COMBO medium for long-term culturing and bioassay testing of Daphnia magna was evaluated in 21-day survival, growth, and reproduction studies. The COMBO medium originally designed for softwater daphnid species (i.e., D. pulicaria) was modified for the hardwater species D. magna. This medium also allowed continuous culturing of a green algal food source for daphnids, Ankistrodesmus falcatus. After 12 generations of culturing in H-H COMBO medium, the mean fecundity was 128 +/- 12 (coefficient of variation = 9.4%). No significant observations of dead young, aborted eggs, or reduced antennas were made during the 6 months of continuous culturing. The no-observable-effect concentration (NOEC) for a reference toxicant standard, 3,4-dichloroaniline (3,4-DCA), was 8.3 micrograms/liter, which is similar to published values. These studies demonstrate that H-H COMBO is an acceptable medium for use for culturing and bioassay testing with D. magna. Additional experiments using frozen aliquots of A. falcatus were conducted. Although mean fecundity (64 +/- 7) and adult length were significantly decreased from the values for daphnids fed fresh algae, the NOEC for 3,4-DCA was > 25 micrograms/liter. The use of this alternative food source in bioassay testing appears promising, but further optimization of feeding rates is warranted.

Aniline Compounds↗
PubMed2002

Toxicity of 40 herbicides to the green alga Chlorella vulgaris.

The effects on the green alga Chlorella vulgaris of 40 herbicides in 19 different chemical structure classes and with 11 dissimilar modes of action were studied through 96-h acute toxicity tests. Experimental results indicated that the average acute toxicity of acetolactate synthase (ALS)-inhibiting herbicides to C. vulgaris was close to those of the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides and the lipid synthesis-inhibiting protoporphyrinogen oxidase (Protox) inhibitor. Their acute toxicities were higher than those of the microtubule process inhibitor, mitotic process inhibitor, the glutamine synthase inhibitors, and 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSP synthase) inhibitors. The acute toxicities of auxin herbicides to C. vulgaris were the lowest among all herbicides tested and that of the photosynthesis-inhibiting herbicides was the highest.

Chlorella↗
PubMed1994

Complete sequence of the mitochondrial DNA of the chlorophyte alga Prototheca wickerhamii. Gene content and genome organization.

The complete nucleotide sequence of the circular mitochondrial (mt) DNA of the chlorophyte alga Prototheca wickerhamii has been determined (55,328 base-pairs, A+T content 74.2%). The genes identified encode three subunits of the cytochome oxidase, apocytochrome b, nine subunits of the NADH dehydrogenase complex (nad1 to 7, nad4L and nad9), three ATPase subunits (atp6, atp9, atp1 (also referred to as atpA)), three ribosomal RNAs (5 S (rrn5), small subunit (srn) and large subunit (lrn) RNA), 26 tRNAs, and 13 ribosomal proteins. A total of five group I introns reside in lrn and cox1, two of which include intronic open reading frames (ORFs). Five free-standing ORFs longer than 60 codons are present. Three of these ORFs are counterparts to genes encoding proteins of unknown function in plant mitochondria (orf25 and orfB of angiosperms and orf244 of liverwort), whereas two of them are unique. Mitochondrial genes are encoded on both DNA strands in a way that suggests the existence of two transcription units, each including approximately one half of the mitochondrial genome. The two intergenic regions in which transcription is believed to initiate and terminate are about ten times longer than the other intergenic regions (1118 and 1993 nt versus 100 to 150 nt). A total of 29 recurring sequence motifs (30 to 200 nt long) have been found in intergenic regions. Nine different types of motifs are present, most of them arranged as tandem repeats. These motifs may be implicated in transcription, e.g. as signals for initiation, termination and/or processing. Phylogenetic analysis on the basis of the cox1 gene strongly suggested that P. wickerhamii and plant mitochondrial genomes are monophyletic. The finding of plant-specific mitochondrial genes such as orf25, orf244, orfB and rrn5 in P. wickerhamii mitochondria corroborates this idea.

Amino Acid Sequence↗
PubMed1995

Myosin from alga Chara: unique structure revealed by electron microscopy.

Cytoplasmic streaming is a fundamental process for the transport of molecules and organelles in plant cells. A myosin-like protein responsible for cytoplasmic streaming in fresh water alga, Chara corallina, has been purified. Electron micrographs of this protein revealed that it has two heads with similar size and shape to those of muscle myosin (myosin II) but its tail was shorter than that of muscle myosin with a globular structure at its distal end like that of myosin V. The myosin cosedimented with vesicles composed of phosphatidyl serine like other non-muscle myosin species involved in intracellular transport.

Actins↗
PubMed1997

A group II self-splicing intron from the brown alga Pylaiella littoralis is active at unusually low magnesium concentrations and forms populations of molecules with a uniform conformation.

We have investigated the reactivity of three of the seven group II introns encoded by the mitochondrial genome of the brown alga Pylaiella littoralis. While the first intron in the protein-coding cox1 gene could not be induced to self-splice under any of the conditions tested, the first two introns in the gene encoding the large ribosomal subunit are reactive in vitro and splice primarily by the standard group II two-step transesterification pathway. Intron 2 proved to be of exceptional interest, because in contrast to all group II molecules known so far, its optimal magnesium concentration is less than 10 mM and it still carries out accurate splicing at concentrations as low as 0.1 mM magnesium. Analysis of reaction products under optimal conditions showed no evidence of hydrolysis at the 5' splice site and up to 90% of precursor molecules could be converted into excised lariat intron, which migrated as a single band on non-denaturing polyacrylamide gels. Absorbance versus temperature profiles generated from the lariat form of intron 2 reveal the existence of an early melting component, the amplitude of which does not depend on the way the molecules were purified, i.e. with or without a denaturation step. This highly cooperative transition, whose position along the temperature axis changes with the concentration of magnesium, is proposed to consist of the unfolding of the tertiary structure of the molecule. We conclude that group II introns, which are the largest known ribozymes, can form conformationally homogeneous populations of molecules suitable for physical-chemical studies of higher-order structure.

Electron Transport Complex IV↗