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The 16S ribosomal RNA of the blue green alga Anacystis nidulans has been characterized in terms of the oligomers generated by digestion with T1 ribonuclease. A. nidulans by this criterion is definitely a procaryote; being no more distant from Bacilli or Enterics than the latter two are from one another. A. nidulans appears to be somewhat more closely related to the Bacilli than to the Enterics.
Rates of change of cell volume were measured in suspensions of the halophilic green algae Dunaliella parva subjected to changes in cation composition and concentration of the outside medium. Measurements were made with a particle size analyzer and results were checked by direct microphotography. For any one salt solution, changes in cell volume with concentration were consistent with the Boyle-Van't Hoff model of an osmometer. Nonosmotic volume comprised 60-80% of total cell volume and was sensitive to the nature of the cation, increasing in the order Cs less than K less than Na less than Ca less than Mg. Kinetics of volume change in response to changes in outside salt concentration are best described by two kinetic coefficients differing by one order of magnitude and dependent on the nature of the outside cation (decreasing in order Cs greater than K greater than Na greater than Mg) as well as on direction of water flow.
Chemical studies of the Caribbean red alga Vidalia obtusaloba have resulted in the isolation of two new bromophenolic metabolites, vidalols A and B (1, 2). The new compounds were discovered as part of an organized effort to isolate new naturally-occurring anti-inflammatory agents with a focus upon those which may function through the inhibition of phospholipase A2.
A new agglutinin has been isolated from the red alga Gracilaria bursa-pastoris by affinity chromatography on a yeast mannan-Cellulofine column. This agglutinin was isolated as a monomeric glycoprotein with a relatively low molecular weight. It had an isoelectric point of 4.7 and contained large amounts of Gly, Asx and Glx. It agglutinated trypsin-treated rabbit erythrocytes at the low concentration of 30 ng/ml. The activity was inhibited only by glycoproteins bearing N-glycans. This agglutinin also showed mitogenic activity for mouse splenic lymphocytes.
A novel ether lipid, (-)-(R)-1-O-geranylgeranylglycerol, has been isolated from the brown alga Dilophus fasciola and its structure proved by spectroscopic methods and chemical degradation.
An unicellular alga, Chlorella pyrenoidosa, which had been reported to protect C3H mice against sarcoma BP8, is shown, when injected in Freund's incomplete adjuvant, to modulate the antibody synthesis induced by immunization with a hapten-carrier complex. C. pyrenoidosa appeared to be able to initiate an antigenic competition between hapten and carrier determinants of the antigen molecule during antibody synthesis, and thus it could be speculated that C. pyrenoidosa modulates the immune response at the macrophage level.
The circadian clock in the unicellular alga Gonyaulax polyedra is accelerated by a substance in extracts from the cells themselves. The extracts have been fractionated using the circadian rhythm of bioluminescence as bioassay. The active substance, termed gonyauline, has been isolated and characterized as a novel low molecular weight cyclopropanecarboxylic acid (S-methyl-cis-2-(methylthio) cyclopropanecarboxylic acid). Synthetic gonyauline has a similar shortening effect on the period of the circadian clock.
The 1788-nucleotide sequence of the small-subunit ribosomal RNA (srRNA) coding region from the chlorophyte Volvox carteri was determined. The secondary structure bears features typical of the universal model of srRNA, including about 40 helices and a division into four domains. Phylogenetic relationships to 17 other eukaryotes, including two other chlorophytes, were explored by comparing srRNA sequences. Similarity values and the inspection of phylogenetic trees derived by distance matrix methods revealed a close relationship between V. carteri and Chlamydomonas reinhardtii. The results are consistent with the view that these Volvocales, and the third green alga, Nanochlorum eucaryotum, are more closely related to higher plants than to any other major eukaryotic group, but constitute a distinct lineage that has long been separated from the line leading to the higher plants.
The chlL gene product is involved in the light-independent synthesis of chlorophyll in photosynthetic bacteria, green algae and non-flowering plants. The chloroplast genome of Chlorella vulgaris strain C-27 contains the first example of a split chlL gene, which is interrupted by 951 bp group I intron in the coding region. In vitro synthesized pre-mRNA containing the entire intron and parts of the flanking exon sequence is able to efficiently self-splice in vitro in the presence of a divalent and a monovalent cation and GTP, to yield the ligated exons and other splicing intermediates characteristic of self-splicing group I introns. The 5' and 3' splice sites were confirmed by cDNA sequencing and the products of the splicing reaction were characterized by primer extension analysis. The absence of a significant ORF in the long P9 region (522 nt), separating the catalytic core from the 3' splice site, makes this intron different from the other known examples of group I introns. Guanosine-mediated attack at the 3' splice site and the presence of G-exchange reaction sites internal to the intron are some other properties demonstrated for the first time by an intron of a protein-coding plastid gene.
By employing a new procedure we have been able to visualize a highly intense actin cytoskeleton in the unicellular green alga Acetabularia acetabulum Silva. The protocol described in this study involves microwave-accelerated simultaneous permeabilization with 10% dimethyl sulphoxide, fixation with 1% glutaraldehyde and incubation with 0.5 microM fluorescein-isothiocyanate-conjugated Phalloidin. Comparison of the images of the actin cytoskeleton of the stalk, as visualized by methods used previously, with those obtained in our own experiments shows that the actin filaments were preserved completely in an excellent condition. The required time for each procedure could be reduced from 12 h for the most commonly used immunofluorescence technique to 35 min. Moreover, it has been possible to observe the actin filament system of hair whorls, rhizoid and tip. Previously, the actin cytoskeleton of these parts of the cell could not be visualized by conventional techniques. It is shown that each region of the cell-stalk, tip, rhizoid and side branches-displays characteristic degrees of actin bundling and regularity of actin alignment.
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.
Three new dihydroxyicosanoids, 12(R),13(R)-dihydroxyicosa-5(Z),8(Z),10(E),14(Z)-tetraenoic acid, 12(R),13(R)-dihydroxyicosa-5(Z),8(Z),10(E),14(Z),17(Z)-pentaeno ic acid and 10(R*),11(R*)-dihydroxyoctadeca-6(Z),8(E),12(Z)-trienoic acid, have been isolated from a previously unstudied temperate red marine alga, Farlowia mollis (Cryptonemiales, Rhodophyta). The structures of these new metabolites have been deduced from detailed nuclear magnetic resonance and mass spectrometry analyses on stabilized diacetate-methyl esters and stereochemistry deduced by 1H NMR couplings and CD analysis of a dibenzoate derivative. Collectively, these new natural products modulate fMLP-induced superoxide anion generation in human neutrophils, inhibit the conversion of arachidonic acid to lipoxygenase products by human neutrophils, and inhibit the functioning of the dog kidney Na+/K+ ATPase.
Mechanisms of transport of secretory products across the Golgi apparatus (GA) as well as of scale formation in prymnesiophytes have remained controversial. We have used a quantitative morphological approach to study formation and transport of scales across the GA in haploid cells of Pleurochrysis sp. The GA of these cells differs from the GA of higher plants in at least six morphological characteristics. Our results show that scales form in the trans-Golgi network (TGN) and transit the TGN in heretofore unrecognized prosecretory vesicles. Prosecretory vesicles differentiate into secretory vesicles prior to exocytosis of scales to the cell surface. Because prosecretory vesicles are only fragments of TGN cisternae, the classical model of cisternal progression is not a valid mechanism of transport in this alga. TGN transport vesicles are also involved in scale formation; however, the role of tubular connections between cisternae of a single stack-TGN unit is not clear. The relationship of two morphological types of cisternal dilations to a membrane-associated, bottlebrush-shaped macromolecule of novel morphology suggests a new hypothesis for the biogenesis of scales.
Lack of nitrogen, phosphorus, or all nutrients, extremes of pH (< 4, > 11), presence of 'heavy' metals (Co, Cu, Zn, Hg, Pb; 0.5-10 ppm) or pesticides (carbofuran, 2,4-D, dithane, phorate, or bavistin; 1-50 ppm) decreased to various extent or completely inhibited the survival or vegetative cells in all studied algae. The formation of akinetes, their viability and germination in Anabaena iyengarii, Westiellopsis prolifica, Nostochopsis lobatus and Pithophora oedogonia and the formation of zoosporangia, their viability, and the germination of zoospores in Cladophora glomerata and Rhizoclonium hieroglyphicum was affected. The formation of viable akinetes or zoosporangia was shown to be directly linked with vegetative cell survival and growth; it could not be induced by any chemical stress imposed.
The effects of varying concentrations of nutrients present in Bold's basal medium on the extent of colony formation from vegetative fragments, sporulation and spore germination of the green alga Stigeoclonium pascheri 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, sporulation was greater in an increasing order in media containing 2- to 10-fold increase in MgSO4. There was a decrease in spore germination in media deficient in phosphates, MgSO4, containing 5- or 10-fold MgSO4, or containing 2- to 10-fold of CaCl2, H3BO3 or microelements. Spore germination increased in media containing 2-fold MgSO4, deficient in H3BO3 or microelements or containing none of the three micronutrient solutions.
Fatty acids from Chlorella vulgaris, Scenedesmus obliquus var. acutus and from a mixed culture of the two strains, Melnik, were converted to methyl esters, separated by gas chromatography, and identified by means of standards. The spectrum of fatty acids included both saturated and unsaturated acids (with odd and even numbers of carbon atoms) from C12 to C22. Fatty acids C16:0, C18:0 and C20:3 were the major components in all cultures. Pure strains differed from the mixed culture in the production of C18:1, C12:0 and C19:2 acids; the first of these was present in higher amounts in pure cultures only, the latter two being found in the mixed culture. The level of lipids was lower as compared to the literature data and their extractability was affected by the manner of preparation of algae and extraction conditions.
The green alga Scenedesmus obliquus was incubated with heavy metals (Cd2+, Zn2+, Mn2+, Ni2+) with and without selenium. S. obliquus exhibited higher rates of growth and some metabolic activities in cultures containing 0.1 mmol/L Se than those only containing the heavy metals. The positive effect of Se was found with all metals but was negligible with Mn2+.
Mathematical expressions were derived for the dilution rate and concentration of algae determining the maximum biomass production in a semicontinuous algal culture.