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At least 631 records · Page 35Linked to original sources
PubMed1993

SecA is plastid-encoded in a red alga: implications for the evolution of plastid genomes and the thylakoid protein import apparatus.

Partial sequence analysis of the plastid DNA (ptDNA) from a red alga, Antithamnion sp., revealed the presence of a homologue to the Escherichia coli secA gene as well as two open reading frames (ORF 510, ORF 179). In addition a sec Y homologue has been detected on the plastid genome by heterologous hybridization. None of these genes has been found in completely sequenced chlorophytic plastid genomes. SecA and secY gene copies were also detected in the ptDNA of a chromophytic alga, indicating that secA Y may be ubiquitous in rhodophytes and chromophytes. The significance of these findings for the evolution of plastid genomes and the thylakoid protein import mechanism is discussed.

Adenosine Triphosphatases↗
PubMed1975

Lampbrush-type chromosomes in the primary nucleus of the green alga Acetabularia mediterranea.

Structures with a lampbruch-chromosome-like morphology are described in the nucleoplasm of primary nuclei of the green alga, Acetabularia mediterranea, by light and electron microscopy in sections of cells fixed in situ and in spread preparations of isolated nuclear components. These chromosomes reveal typical loops (up to 20 micronm long), chromomere-like nodules (1-2 micronm in diameter), and 2-4 micronm large axial globules. Associations of some of these chromosomes with nucleolar structures and with the nuclear envelope are also recognized. The light microscopically identified loops are correlated with distinct fibrillogranular structures observed in the thin sections and with the very long matrix units seen in the spread preparations. The similarity of these structures to the lampbrush chromosomes of various animal cell types, all exclusively stages of meiotic prophase, is discussed as well as the possible relation of the appearance of lampbrush chromosomes to a defined phase of the vegatative growth of this alga.

Acetabularia↗
PubMed1995

The gene family encoding the fucoxanthin chlorophyll proteins from the brown alga Macrocystis pyrifera.

Six members of a multigene family encoding polypeptide constituents of the fucoxanthin, chlorophyll a/c protein complex from female gametophytes of the brown alga Macrocystis pyrifera have been cloned and characterized. The deduced amino acid sequences are very similar to those of fucoxanthin chlorophyll binding proteins (Fcp) from the diatom Phaeodactylum tricornutum and exhibit limited homology to chlorophyll a/b binding (Cab) polypeptides from higher plants. The primary translation products from the M. pyrifera fcp genes are synthesized as higher molecular weight precursors that are processed prior to their assembly into the Fcp complex. The presumed N-terminal 40-amino acid presequence of the Fcp precursor polypeptide has features resembling that of a signal sequence. This presequence may be required for the protein to transverse the endoplasmic reticulum that surrounds the plastid in brown algae. A subsequent targeting step would be required for the protein to cross the double membrane of the plastid envelope. M. pyrifera fcp transcripts are of two sizes, 1.2 and 1.6 kb. The size difference is accounted for by the length of the 3' untranslated region, which can be up to 1000 bases. Transcript abundance's of members of the fcp gene family are dependent on light quantity, light quality, or both. Transcript levels of one gene increased approximately five- to tenfold in thalli grown in low intensity relative to high intensity white or blue light. Transcripts from this gene also significantly increase in red light relative to blue light at equivalent light intensities.

Amino Acid Sequence↗
PubMed1994

Physical map of the plastid genome of the unicellular red alga Cyanidium caldarium strain RK-1.

The physical map of the plasmid genome of the unicellular red alga Cyanidium caldarium strain RK-1 was constructed. The 150-kbp genome was circular and had an inverted repeated region (IR) which contained the genes for 16 s and 23 s ribosomal RNAs, as is usually seen in most plastid genomes. Since C. caldarium is a very "primitive" alga, the results suggest that the ancestral cyanobacteria lost most of its genome as an endosymbiont comparatively early in the process of plastid formation. After that, several genes seem to have been lost from plastid genomes, step by step, during the course of evolution.

Amino Acid Sequence↗
PubMed1994

Cloning and characterization of the nuclear gene encoding plastid glyceraldehyde-3-phosphate dehydrogenase from the marine red alga Gracilaria verrucosa.

The single-copy nuclear gene (GapA), encoding the plastid-localized glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of the marine red alga Gracilaria verrucosa, has been cloned and sequenced. The GapA transcriptional initiation site was located 49 bp upstream of the start codon, and a putative TATA box was found 54 bp farther upstream. A spliceosomal intron was identified in the transit-peptide-encoding region in a position very similar to intron 1 of GapA and GapB of higher plants; no introns occur in the region encoding the mature protein. These observations provisionally suggest that both red algae and higher plants descend from a single ancestral photosynthetic eukaryote, i.e. that a single endosymbiotic event gave rise to red algal and higher-plant plastids.

Amino Acid Sequence↗
PubMed1995

The nuclear gene and cDNAs encoding cytosolic glyceraldehyde-3-phosphate dehydrogenase from the marine red alga Gracilaria verrucosa: cloning, characterization and phylogenetic analysis.

We have cloned and sequenced the single-copy nuclear gene (GapC) encoding the complete 335-amino acid cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) from the red alga Gracilaria verrucosa. The proline residue which contributes to the specificity of NAD+ binding in other GAPC-like proteins is present. Putative regulatory regions, including GC-rich regions, a GATA element, and 11-base T- and T/G-clusters, but excluding TATA- and CCAAT-boxes, were identified upstream. Two types of GapC cDNAs differing in polyadenylation site were characterized. An 80-bp phase-two spliceosomal intron was identified in a novel position interrupting the highly conserved cofactor-coding region I. The G. verrucosa GAPC was easily aligned with other known GAPC-type sequences. Inferred phylogenetic trees place red algae among the eukaryote crown taxa, although with modest bootstrap support and without stable resolution among related GAPC lineages.

Amino Acid Sequence↗
PubMed1993

Two amino-acid biosynthetic genes are encoded on the plastid genome of the red alga Porphyra umbilicalis.

To isolate the gene encoding the amino-acid biosynthetic enzyme acetolactate synthase (ALS) from the red alga Porphyra umbilicalis, PCR experiments were carried out using P. umbilicalis DNA as the template and degenerate oligonucleotides representing conserved regions of ALS amino-acid sequences. Interestingly, the PCR product (0.9 kb) hybridized exclusively to the plastid DNA of this red alga. DNA sequencing of two contiguous EcoRI plastid DNA clones revealed a 590 amino-acid open reading frame with 55 to 61% identity to cyanobacterial ALS sequences. A second gene (argB) encoding another amino-acid biosynthetic enzyme, N-acetylglutamate kinase, was identified upstream of, and on the opposite strand to the gene encoding ALS (ilvB). This is the first molecular characterization of a gene for an arginine biosynthetic enzyme from any plant. In addition, two tRNA genes, trnT(GGU) and trnY(GUA), were detected downstream from ilvB while four tRNA genes, trnfM(CAU), trnA(GGC), trnA(GGC), trnS(-GCU) and trnD(GUC), were found downstream from argB. trnA(GGC) is not found in the chloroplast genomes of land plants.

Acetolactate Synthase↗
PubMed1975

In vitro repair of UV-or x-irradiated bacteriophage T4 DNA by extract from blue-green alga Anacystis nidulans.

The cell-free extract from blue-green alga Anacystis nidulans contains enzymatic activities which repair in vitro transforming DNA of bacteriophage T4 damaged by UV light or X-rays. The repair effect of the extract was observed with double-stranded irradiated DNA but not with denatured irradiated DNA. The level of restoration of the transforming activity depends on the protein concentration in the reaction mixture and on the dose of irradiation. A fraction of DNA lesions induced by X-rays is repaired by a NAD-dependent polynucleotide ligase present in the extract. The repair of UV-induced lesions is the most efficient in the presence of magnesium ions, NAD, ATP and the four deoxynucleoside triphosphates. The results indicate that the repair of UV-irradiated DNA is performed with the participation of DNA polymerase and polynucleotide ligase which function in the cell-free extract of the algae on the background of a low deoxyribonuclease activity.

Adenosine Triphosphate↗
PubMed1989

The genes of both subunits of ribulose-1,5-bisphosphate carboxylase constitute an operon on the plastome of a red alga.

Plastid (pt) DNA from the red alga Porphyridium aerugineum was purified by CsCl gradient centrifugation. An EcoRI library of the ptDNA was screened with a gene probe specific for the gene encoding the large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco EC 4.1.1.39) from spinach. A 5.8 kb EcoRI clone containing the LSU gene (rbcL) was isolated and the DNA sequence of the Porphyridium rbcL gene and its flanking regions was determined. An open reading frame was found 130 bp downstream from the rbcL gene that shows homology to genes coding for the small subunit of Rubisco (rbcS) from higher plants and cyanobacteria. Both genes (rbcL + rbcS) are cotranscribed. Comparison of rbcL and rbcS sequences from Porphyridium, higher plants and cyanobacteria seems to reveal a remarkable evolutionary distance between the plastids of the red algae (rhodoplasts), chloroplasts and cyanobacteria.

Amino Acid Sequence↗
PubMed1978

Flow cytometric determinations of cellular substances in algae, bacteria, moulds and yeasts.

The practical use of flow cytometry is shown in several microbial assays. Recent technical improvements in the optics and electronics of flow cytometric systems as well as in staining techniques permit the measurements of minute cellular components such as the cellular DNA and the protein content of bacteria, algae, moulds and yeasts. Single cell ingredients can be measured by this assay according to their specific stainability. The cell DNA was stained by propidium iodide while the cell protein was fluorochromed by fluorescein-iso-thiocyanate. The DNA synthesis of Saccharomyces cerevisiae and Saccharomyces pastorianus runs discontinuously while the protein content increases continuously during the vegetative growth. The different stages of DNA synthesis of yeast cells can be divided into two 'gap' phases, a synthesis and a mitosis period, corresponding to Howard and Pelc's model of DNA synthesis. Living and dead cells can be counted differentially after staining with Erythrosine B. The red fluorescence of the chlorophyll in algae can readily be used to determine the chlorophyll content of these cells.

Bacterial Proteins↗
PubMed1976

Halophilic-blue-green algae.

The isolation of a halophilic blue-green alga, Aphanothece halophytica, from Great Salt Lake is described. The organism was cultured from waters with salinities up to saturated NaC1 (about 30% w/v). It has an optimum salinity for growth of about 16% NaC1, but can grow very slowly even in saturated NaC1. Based on the study of the Great Salt Lake organism, and on a review of the earlier literature, it is concluded that despite recent reports to the contrary, true halophilic blue-green algae do exist.

Cyanobacteria↗
PubMed1977

Influence of electric fields on photophobic reactions in blue-green algae.

The effect of external electric fields on photo-accumulations of Phormidium uncinatum in light traps has been studied. 1. In direct current fields the phobic reaction of trichoms leaving the light field is not impaired if a voltage of 2.5 V is not exceeded. With voltages between 3 and 7 V the trichoms are motile, but phobic reactions are cancelled, provided the organisms are oriented more or less parallel to the electric field lines. Higher voltages cause the algae to die within minutes. 2. Only alternating current fields of very low frequencies (less than or equal 10(-3) Hz) have similar effects. Sine waves are more effective than triangular ones, but less than square waves. A hypothesis is proposed according to which sensory transduction of photophobic reactions in blue-green algae is mediated by changes in the endogenous membrane potential. This potential might be interfered with by the application of an external electric field, thus inhibiting photophobic reactions.

Cyanobacteria↗
PubMed1975

Photoreactivation of UV-irradiated blue-green algae and algal virus LPP-1.

Ultraviolet (UV) sensitivity and photoreactivation of blue-green algae Cylindrospermum sp., Plectonema boryanum, spores of Fischerella muscicola and algal virus (cyanophage) LPP-1 were studied. The survival value after UV irradiation of filaments of Cylindrospermum sp. and Virus LPP-1 showed exponential trend and these were comparatively sensitive towards UV than F.muscicola and P.boryanum. Photoreactivation of UV-induced damage occurred in black, blue, green, yellow, red and white light in Cylindrospermum sp., however only black, blue and white light were capable of photorepair of UV-induced damage in P.boryanum, spores of F.muscicola and virus LPP-1 in infected host alga. Pre-exposure to yellow and black light did not show photoprotection. The non-heterocystous and nitrogen fixation-less mutants of Cylindrospermum sp. were not induced by UV and their spontaneous mutation frequency was not affected after photoreactivation. The short trichome mutants of P.boryanum were more resistant towards UV. The occurrence of photoreactivation of UV-induced killing wide range of light in Cylindrospermum sp. is the first report in organisms.

Cell Survival↗
PubMed1986

Antifungal activity of some mediterranean algae.

The antifungal activity of 15 mediterranean algae species on some dermatophyte strains (Epidermophyton floccosum, Microsporum canis, M. gypseum and Trichophyton mentagrophytes) and pathogenic yeasts (Candida albicans, C. guillermondii, C. krusei, C. tropicalis and Torulopsis glabrata) has been tested following a modification of Aubert's technique. Among the algae species studied, Falkenbergia rufolanosa is the most active in front of all the fungi tested.

Antifungal Agents↗
PubMed1976

Ion metabolism in a halophilic blue-green alga, Aphanothece halophytica.

The intracellular ion content of the halophilic blue-green alga, Aphanthece halophytica was studied as a function of age, external sodium and external potassium concentration. Intracellular Na+ was found to be about 0.38 millimoles/g dry mass. Intracellular K+ concentrations were as high as 1 M and varied directly with external salinity. Intracellular Ca++ and Mg++ were in the range previously reported for fresh water blue-green algae despite their extremely high extracellular concentrations. Average cell size is consistent at room temperature with two exceptions. When the outside K+ is lower than 6.5 mM the cells tend to be smaller with less intracellular K+ and high Ca++. In stationary phase cultrues the cells are larger with high intracellular Mg++ and low K+.

Calcium↗
PubMed1976

Studies on utilization of 2-ketoglutarate, glutamate and other amino acids by the unicellular alga Cyanidium caldarium.

Two strains of Cyandium caladarium which possess different biochemical and nutritional characteristics were examined with respect to their ability to utilize amino acids or 2-ketoglutarate as substrates. One strain utilizes alanine, glutamate or aspartate as nitrogen sources, and glutamate, alanine, or 2-ketoglutarate as carbon and energy sources for growth in the dark. The growth rate in the dark on 2-ketoglutarate is almost twice as high or higher than that on glutamate or alanine. During growth or incubation of this alga on amino acids, large amounts of ammonia are formed; however, ammonia formation is strongly inhibited by 2-ketoglutarate. The capacity of the alga and develops fully only when the cells are grown or incubated in the presence of glutamate.

Alanine↗
PubMed1976

Cyclic condensed metaphosphates and linear polyphosphates in brown and red algae.

The occurrence of linear condensed polyphosphates and cyclic condensed metaphosphates was studied by means of pulse-labeling with 32P-orthophosphate (3--5h) in a number of Phaeophyceae species: Pylaiella litoralis, Ilea fascia, Ectocarpus siliculosus and also Rhodophyceae species: Ceramiumdeslongchampsii, C. rubrum, Rhodomela confervoides, Porphyridium purpureum and P. aerugineum. Two-dimensional cellulose thin layer chromatography revealed that in all species studied 32P-radioactivity was generally present in all oligopolyphosphates containing 2 to 7 phosphate residues, in cyclic metaphosphates (tri-, tetra-, penta- and hexametaphosphates) and in high-molecular-weight condensed phosphates which remained at the starting point. Among the low-molecular-weight condensed inorganic phosphates the trimetaphosphate had a significantly higher specific activity than the other oligophosphates which were separated on the chromatography plates as measured by the direct scanning with a Geiger-Muller counter. The phosphate uptake strongly depends on the internal pool of reserve phosphates of the algae cells. The 32P-orthophosphate incorporation of the cells is low and sluggish when growning in a synthetic medium or in sea water. Accordingly 32P appeared preferentially in the low-molecular-weight fractions of condensed phosphates since the storage phosphates were not yet used. After previous incubation in a P-free culture medium of the algae the 32P was rather rapidly incorporated and was found mostly in the high-molecular-weight condensed phosphates. During MAK-chromatography the high-molecular-weight fractions were eluted together with the nucleic acids (tRNA and DNA) while most of the low-molecular-weight fractions left the column immediately on elution.

Eukaryota↗
PubMed1996

Sludge-Grown Algae for Culturing Aquatic Organisms: Part I. Algal Growth in Sludge Extracts

This project is aimed at studying the feasibility of using sewage sludge to prepare culture media for microalgae (Chlorella-HKBU) and the use of the sludge-grown algae as a feed for some aquatic organisms. Part I of the project included results on preparing sludge extracts and their use on algal culture. By comparing two culturing techniques, "aeration" and "shaking," it was noted that both lag and log phases were shortened in the aeration system. A subsequent experiment noted that algal growth subject to aeration rates of 1.0 and 1.5 liters/min had similar lag and log phases. In addition, both aeration rates had a significantly higher (P<0.05) final cell density than that of 0.5 liters/min. A detailed study on the variation of growth conditions on the algal growth was done. The results indicated that pH values of all the cultures declined below 5 at day 12. The removal rates of ammonia N ranged from 62% to 70%. The sludge-grown algae contained a rather substantial amount of heavy metals (&mgr;g/g): Zn 289-581, Cu 443-682, Ni 310-963, Mn 96-126, Cr 25-118, and Fe 438-653. This implied that the rather high levels of heavy metals may impose adverse effects on higher trophic organisms.

Journal Article↗