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Sterol and Fatty Acid compositions of a marine alga bryopsis pennata (bryopsidophyceae, chlorophyta).

The green alga Bryopsis pennata Lamouroux, collected from the coast of Karachi, has been investigated for its sterol and fatty acid compositions. Four sterols and 19 fatty acids have been isolated from methanolic extract of this alga and identified by (1)H-NMR, El- & GC-MS techniques. The sterol having cholesta skeleton was found as major constituent (78.12%), while other three with ergosta skeleton occurred in traces (5-9%). Seven saturated fatty acids were present in greater quantity (72.58%) than 12 unsaturated ones (27.41%). The latter included 7 monoenoic, 2 dicnoic, 2 trienoic and 1 pentaenoic adds. Tricosanoic acid was found in the highest amount (30.24%), cyclopentenyl undecanoic and heneicosapentaenoic acids were the unique and rare fatty acids detected.

Journal Article↗

Effects of various agents on flagellar activity, flagellar autotomy and cell viability in four species of Chlamydomonas (chlorophyta: volvocales).

Over 200 strains of green algal flagellates, representing about 100 species, were examined for their suitability as experimental organisms for studies of flagellar activity. The cells of all species shed their flagella under unfavourable conditions of temperature or pH, or in the presence of alcohols, detergents or toxic agents of various kinds. For further studies of flagellar activity, motility and autotomy (biologically induced shedding) in particular, we selected four species of Chlamydomonas: C. dysosmos Moewus, C. moewusii Gerloff, C. monoica Strehlow and C. reinhardtii Dangeard. Agents found to inhibit motility without inducing death or flagellar autotomy included azide, arsenite, thiosulphate, cyanide, ferricyanide, hydroxylamine, chloral hydrate, malonate, p-chloro-mercury benzoate and cytochalasin-B, each in a limited range of concentrations which differed according to species and strain. Higher concentrations of these agents caused the flagella to be shed. Since flagellar autotomy is a means by which a cell can quickly reduce the area of its permeable surface, it may have a positive survival value for species liable to be subjected to unfavourable physicochemical conditions.

Azides↗

Production of single cell protein from five strains of the microalga Chlorella spp. (Chlorophyta).

Single cell protein (SCP) production by five strains of Chlorella species (M109, M121, M122, M138, M150), isolated from different habitats, was studied under the influence of eight environmental factors. The ranges for biomass production and SCP were 150-260 mg/l, and 12.4-49.7% dry wt, respectively. The ranges of SCP under the influence of temperature, light, nitrate, ammonia, phosphorus, iron, carbonate, and sodium chloride were in the following respective order (% dry wt): 18.4-43.3, 20.5-42.3, 12.4-35.8, 15.7-41.8, 15.8-49.4, 17.4-49.7, 13.8-35.6, and 0.0-37.7. All the environmental factors had a positive effect on SCP of the five strains except that sodium chloride had a negative effect on SCP of M150. According to these results, both biomass and SCP production can be manipulated and optimized for commercial use by varying the environmental factors used here.

Biomass↗

[On the problem og higher fungi origin: Florideae hypothesis].

The history and current state of the hypothesis of the origin of higher fungi (Ascomycetes and Basidiomycetes) and red algae from the common ancestor (Florideae) were analysed. Initially the hypothesis was based on similarity of their vegetative and generative structures (Sachs, 1874; Dodge, 1914; Chadefaund, 1953, 1972, etc.), but later it was confirmed by ultrastructural data (Demoulin, 1974; Kohlmeyer, 1975). It appears to be very useful for the study of the development of terrestrial flora (Church, 1921; Kohlemeyer, Kohlmeyer, 1979; Atsatt, 1988) and regularities in morphological evolution of higher fungi (Corner, 1964, 1970; Chadefaud, 1960, 1982, 1984). Description of the order Spathulosporales (Kohlmeyer, 1973), combining the characters of Ascomycetes and parasitic Florideae, was one of the most important fact leading to the wide recognition of the hypothesis in 1970-80s (Cavalier-Smith, 1978; Taylor, 1978; Dodge, 1980; Hawksworth, 1982; Goff, 1983; Coff, Coleman, 1985). Today, however, Florideae hypothesis is not confirmed by molecular data and replaced by alternative hypothesis of Eumycota origin. Summarizing data on molecular systematic of fungi, one could affirm with confidence: 1). Chitincontaining fungi are closer to multicellular animals and green plants than to Rhodophyta; 2). Rhodophyta and Chlorophyta are monophyletic group; 3). There is no single-valued molecular data on taxonomic distance between higher fungi, Chytridiomycetes; Rhodophyta, Chlorophyta and Metazoa. Thus, the current data could not testify against Florideae hypothesis. It is possible to adjust them with the idea of B.M. Kozo-Polyansky (1927) about existence of "Chloroflorodeae" group that is original for terrestrial flora; the hypothesis about closeness of Chlorophyta and Rhodophyta, as well as Chlorophyta and Eumycota, does not contradict molecular data (Stiller, Hall, 1997). The author believes that we need molecular study of the whole "stem" of chlorobionta, especially groups that are close to its basis. It will will help to understand the relationships between Rhodophyta, giant conglomeration of "green algae", chitin-containing fungi, Prasinophyceae and different groups of zoomastigot with maximal resolution--the level of orders or groups of orders. Only such investigation could provide the material for molecular support of phylogenetic constructions. Up to moment Florideae hypothesis is able to exist together with the other ideas.

Ascomycota↗

Actin phylogeny identifies Mesostigma viride as a flagellate ancestor of the land plants.

Green algae and land plants trace their evolutionary history to a unique common ancestor. This "green lineage" is phylogenetically subdivided into two distinct assemblages, the Chlorophyta and the Streptophyta. The Chlorophyta includes the Chlorophyceae, Trebouxiophyceae, Ulvophyceae, and Prasinopohyceae, whereas the Streptophyta includes the Charophyceae plus the bryophytes, ferns, and all other multicellular land plants (Embryophyta). The Prasinophyceae is believed to contain the earliest divergences within the green lineage. Phylogenetic analyses using rDNA sequences identify the prasinophytes as a paraphyletic taxon that diverges at the base of the Chlorophyta. rDNA analyses, however, provide ambiguous results regarding the identity of the flagellate ancestor of the Streptophyta. We have sequenced the actin-encoding cDNAs from Scherffelia dubia (Prasinophyceae), Coleochaete scutata, Spirogyra sp. (Charophyceae), and the single-copy actin gene from Mesostigma viride (Prasinophyceae). Phylogenetic analyses show Mesostigma to be the earliest divergence within the Streptophyta and provide direct evidence for a scaly, biflagellate, unicellular ancestor for this lineage. This result is supported by the existence of two conserved actin-coding region introns (positions 20-3, 152-1), and one intron in the 5'-untranslated region of the actin gene shared by Mesostigma and the embryophytes.

Actins↗

Antibiotic activity of marine algae against multi-antibiotic resistant bacteria.

The antibiotic activity of six species of marine algae (Rhodophyta, Phaeophyta and Chlorophyta) against multi-antibiotic resistant (MAR) bacteria was investigated. The study shows that various degrees of activity were present in 18 out of the 24 algal extracts. The highest activity was for Rhodophyta (diameter of the inhibited zone ranged from 10-22 mm), whilst the lowest was for Chlorophyta (8-12 mm). The taxonomic trends were seen between extracts, as the best solvents were found to be ether, methanol and acetone for Rhodophyta, Phaeophyta and Chlorophyta, respectively. The importance of these results on public health are discussed.

Anti-Bacterial Agents↗

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

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.

Journal Article↗

[Ecological characteristics of phytoplankton in waters of biological-controlling and ordinary rice fields].

Through investigations from March to June 1998 on the phytoplankton in waters of biological-controlled and ordinary rice fields, 112 species of phytoplankton were found, of which, Bacillariophyta, Euglenophyta and Chlorophyta were dominant. The comparison of the species in two rice fields showed that in biological-controlled rice field, there were more species of Euglenophyta, with 5 most dominant species, i.e., 2 of Euglenophyta, 2 of Bacillariophyta and 1 of Chlorophyta. In ordinary rice field, there were more Bacillariophyta species, in which, 5 most dominant species belonged to Bacillariophyta, except Scenedesmus bijuga to Chlorophyta. The biodiversities of phytoplankton and their evennesses were also analyzed with the period from the seedlings being planted to the rice fields being dried, showing that a little increase in their biodiversity mainly caused by the increase of species number and an evident decrease in their evennesses.

Ecosystem↗

Mapping of picoeucaryotes in marine ecosystems with quantitative PCR of the 18S rRNA gene.

A quantitative PCR (QPCR) assay based on the use of SYBR Green I was developed to assess the abundance of specific groups of picoeukaryotes in marine waters. Six primer sets were designed targeting four different taxonomic levels: domain (Eukaryota), division (Chlorophyta), order (Mamiellales) and genus (Bathycoccus, Micromonas, and Ostreococcus). Reaction conditions were optimized for each primer set which was validated in silico, on agarose gels, and by QPCR against a variety of target and non-target cultures. The approach was tested by estimating gene copy numbers for Micromonas, Bathycoccus, and Ostreococcus in seawater samples to which cultured cells were added in various concentrations. QPCR was then used to determine that rRNA gene (rDNA) copy number varied from one to more than 12,000 in 18 strains of phytoplankton. Finally, QPCR was applied to environmental samples from a Mediterranean Sea coastal site and the results were compared to those obtained by Fluorescent in situ hybridization (FISH). The data obtained demonstrate that Chlorophyta and more specifically Mamiellales were important in these waters, especially during the winter picoplankton bloom. The timing of major abundance peaks of the targeted species was similar by QPCR and FISH. When used in conjunction with other techniques such as FISH or gene clone libraries, QPCR appears as very promising to quickly obtain data on the ecological distribution of important phytoplankton groups. Data interpretation must take into account primer specificity and the varying rRNA gene copy number among eukaryotes.

Animals↗

Inhibition of thrombin by sulfated polysaccharides isolated from green algae.

Eight different sulfated polysaccharides were isolated from Chlorophyta. All exhibited thrombin inhibition through a heparin cofactor II (HCII)-dependent pathway, and their effects on the inhibition of thrombin were more potent than those of heparin or dermatan sulfate. In particular, remarkably potent thrombin inhibition was found for the sulfated polysaccharides isolated from the Codiales. In the presence of these sulfated polysaccharides, both the recombinant HCII (rHCII) variants Lys(173)-->Leu and Arg(189)-->His, which are defective in interactions with heparin and dermatan sulfate, respectively, inhibited thrombin in a manner similar to native rHCII. This result indicates that the binding site of HCII for each of these eight sulfated polysaccharides is different from the heparin- or dermatan sulfate-binding site. All the sulfated polysaccharides but RS-2 significantly stimulated the inhibition of thrombin by an N-terminal deletion mutant of HCII (rHCII-Delta74). Furthermore, hirudin(54-65) decreased only 2-5-fold the rate of thrombin inhibition by HCII stimulated by the sulfated polysaccharides, while HD22, a single-stranded DNA aptamer that binds exosite II of thrombin, produced an approximately 10-fold reduction in this rate. These results suggest that, unlike heparin and dermatan sulfate, the sulfated polysaccharides isolated from Chlorophyta activate HCII primarily by an allosteric mechanism different from displacement and template mechanisms.

Antithrombins↗

Ancestral chloroplast genome in Mesostigma viride reveals an early branch of green plant evolution.

Sequence comparisons suggest that all living green plants belong to one of two major phyla: Streptophyta (land plants and their closest green algal relatives, the charophytes); and Chlorophyta (the rest of green algae). Because no green algae are known that pre-date the Streptophyta/Chlorophyta split, and also because the earliest diverging green algae show considerable morphological variation, the nature of the unicellular flagellate ancestor of the two green plant phyla is unknown. Here we report that the flagellate Mesostigma viride belongs to the earliest diverging green plant lineage discovered to date. We have sequenced the entire chloroplast DNA (118,360 base pairs) of this green alga and have conducted phylogenetic analyses of sequences derived from this genome. Mesostigma represents a lineage that emerged before the divergence of the Streptophyta and Chlorophyta, a position that is supported by several features of its chloroplast DNA. The structure and gene organization of this genome indicate that chloroplast DNA architecture has been extremely well conserved in the line leading to land plants.

Chlorophyta↗

The complete chloroplast DNA sequence of the green alga Nephroselmis olivacea: insights into the architecture of ancestral chloroplast genomes.

Green plants seem to form two sister lineages: Chlorophyta, comprising the green algal classes Prasinophyceae, Ulvophyceae, Trebouxiophyceae, and Chlorophyceae, and Streptophyta, comprising the Charophyceae and land plants. We have determined the complete chloroplast DNA (cpDNA) sequence (200,799 bp) of Nephroselmis olivacea, a member of the class (Prasinophyceae) thought to include descendants of the earliest-diverging green algae. The 127 genes identified in this genome represent the largest gene repertoire among the green algal and land plant cpDNAs completely sequenced to date. Of the Nephroselmis genes, 2 (ycf81 and ftsI, a gene involved in peptidoglycan synthesis) have not been identified in any previously investigated cpDNA; 5 genes [ftsW, rnE, ycf62, rnpB, and trnS(cga)] have been found only in cpDNAs of nongreen algae; and 10 others (ndh genes) have been described only in land plant cpDNAs. Nephroselmis and land plant cpDNAs share the same quadripartite structure-which is characterized by the presence of a large rRNA-encoding inverted repeat and two unequal single-copy regions-and very similar sets of genes in corresponding genomic regions. Given that our phylogenetic analyses place Nephroselmis within the Chlorophyta, these structural characteristics were most likely present in the cpDNA of the common ancestor of chlorophytes and streptophytes. Comparative analyses of chloroplast genomes indicate that the typical quadripartite architecture and gene-partitioning pattern of land plant cpDNAs are ancient features that may have been derived from the genome of the cyanobacterial progenitor of chloroplasts. Our phylogenetic data also offer insight into the chlorophyte ancestor of euglenophyte chloroplasts.

Chlorophyta↗

Seaweeds along KwaZulu-Natal Coast of South Africa--4: Elemental uptake by edible seaweed Caulerpa racemosa (sea grapes) and the arsenic speciation.

The elemental uptake by edible seaweed Caulerpa racemosa (Sea grapes), a marine macroalgae (chlorophyta, green alga) grown richly along KwaZulu-Natal coastline. The total concentrations of seven elements, namely Mn, Fe, As, B, Ti, Zn and Hg in Caulerpa racemosa were monitored for a one-year cycle (June 2002 to May 2003) at four selected sampling sites spread over 150 km wide from North to South. The C. racemosa possess high arsenic, boron and titanium accumulating ability, but low iron uptake. A typical C. racemosa sample at Treasure Beach in the vicinity of Durban Metropolis in autumn contained Mn (5.2+/-ppm), Fe (0.21+/-0.01 ppm), As (8.5+/-0. ppm), B (1090+/-ppb), Ti (159+/-ppb), Zn (3.8+/-0.1 ppb), and Hg (189+/-ppb). The general trend found at all sites was high elemental concentrations in winter and a decrease in concentrations from winter to spring and summer. C. racemosa recorded highest mercury levels (>205 ppb) during the summer season at the Zinkwasi site. The arsenic speciation in four abundant seaweeds from the beaches of Indian Ocean in the KwaZulu-Natal coast is investigated. The speciation of arsenic in two rhodophyta seaweeds, Plocamium corallorhiza and Gelidium abbottiorum, and two chlorophyta seaweeds, Ulva lactuca and Caulerpa racemosa at four sampling sites during the summer of 2003, is elucidated. Caulerpa racemosa had highest total arsenic (in ppb) reaching (8850+/-200) at Zinkwasi, and the concentrations of the other arsenic species analysed are As (III) (194+/-10), As(V) (568+/-27), methylarsonic acid (494+/-22) and dimethylarsinic acid (373+/-12). In an indirect estimation, C. racemosa had 81+/-2% aresenosugars.

Arsenic↗

Nuclear DNA content estimates in multicellular green, red and brown algae: phylogenetic considerations.

BACKGROUND AND AIMS: Multicellular eukaryotic algae are phylogenetically disparate. Nuclear DNA content estimates have been published for fewer than 1 % of the described species of Chlorophyta, Phaeophyta and Rhodophyta. The present investigation aims to summarize the state of our knowledge and to add substantially to our database of C-values for theses algae. METHODS: The DNA-localizing fluorochrome DAPI (4', 6-diamidino-2-phenylindole) and RBC (chicken erythrocyte) standard were used to estimate 2C values with static microspectrophotometry. KEY RESULTS: 2C DNA contents for 85 species of Chlorophyta range from 0.2-6.1 pg, excluding the highly polyploidy Charales and Desmidiales with DNA contents of up to 39.2 and 20.7 pg, respectively. 2C DNA contents for 111 species of Rhodophyta range from 0.1-2.8 pg, and for 44 species of Phaeophyta range from 0.2-1.8 pg. CONCLUSIONS: New availability of consensus higher-level molecular phylogenies provides a framework for viewing C-value data in a phylogenetic context. Both DNA content ranges and mean values are greater in taxa considered to be basal. It is proposed that the basal, ancestral genome in each algal group was quite small. Both mechanistic and ecological processes are discussed that could have produced the observed C-value ranges.

Cell Nucleus↗

The chloroplast genome sequence of the green alga Pseudendoclonium akinetum (Ulvophyceae) reveals unusual structural features and new insights into the branching order of chlorophyte lineages.

One major lineage of green plants, the Chlorophyta, is represented by the green algal classes Prasinophyceae, Ulvophyceae, Trebouxiophyceae, and Chlorophyceae. The Prasinophyceae occupies the most basal position in the Chlorophyta, but the branching order of the Ulvophyceae, Trebouxiophyceae, and Chlorophyceae remains unresolved. The chloroplast genome sequences currently available for representatives of three chlorophyte classes have revealed that this genome is highly plastic, with Chlamydomonas (Chlorophyceae) and Chlorella (Trebouxiophyceae) showing fewer ancestral features than Nephroselmis (Prasinophyceae). We report the 195,867-bp chloroplast DNA (cpDNA) sequence of Pseudendoclonium akinetum (Ulvophyceae), a member of the class that has not been previously examined for detailed cpDNA analysis. This genome shares common evolutionary trends with its Chlorella and Chlamydomonas homologs. The gene content, number of ancestral gene clusters, and abundance of short dispersed repeats in Pseudendoclonium cpDNA are intermediate between those observed for Chlorella and Chlamydomonas cpDNAs. Although Pseudendoclonium cpDNA features a large inverted repeat, its quadripartite structure is unusual in displaying an rRNA operon transcribed toward the large single-copy (LSC) region and a small single-copy region containing 14 genes that are normally found in the LSC region. Twenty-seven group I introns lie in nine genes and fall within four subgroups (IA1, IA2, IA3, and IB); 19 encode putative homing endonucleases, and 7 have homologs at identical insertion sites in other chlorophyte or streptophyte organelle genomes. The high similarity observed among the 14 IA1 and 7 IA2 introns and their encoded endonucleases suggests that many introns arose from intragenomic proliferation of a few founding introns in the lineage leading to Pseudendoclonium. Interestingly, one intron (in atpA) and some of the dispersed repeats also reside in Pseudendoclonium mitochondria, providing strong evidence for interorganellar lateral transfer of these genetic elements. Phylogenetic analyses of 58 cpDNA-encoded proteins and genes support the hypothesis that the Ulvophyceae is sister to the Trebouxiophyceae but cannot eliminate the hypothesis that the Ulvophyceae is sister to the Chlorophyceae. We favor the latter hypothesis because it is strongly supported by phylogenetic analyses of gene order data and by independent structural evidence based on shared gene losses and rearrangement break points within ancestrally conserved gene clusters.

Animals↗