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At least 721 records · Page 40Linked to original sources
PubMed1993

Reverse transcriptase families and a copia-like retrotransposon, Osser, in the green alga Volvox carteri.

By using the polymerase chain reaction (PCR) we have isolated and sequenced two distinct families of reverse transcriptase (RT) sequences from the genome of the colonial alga, Volvox carteri. Probing a genomic library with these RT clones revealed copia-like retrotransposons. One of these elements, named Osser, is 4,875 bp long, bordered by 197-bp identical long terminal repeats (LTRs), and shows the typical organization of retrotransposons belonging to the copia-Tyl group. This is the first complete copia-like retrotransposon sequence described in a green alga.

Amino Acid Sequence↗
PubMed1992

Analysis of sterol esters from alga and yeast by high-performance liquid chromatography and capillary gas chromatography-mass spectrometry with chemical ionization.

Sterol esters from the green alga Chlorella kessleri and the yeast Saccharomyces cerevisiae were analysed by tandem high-performance liquid chromatography (HPLC-HPLC). Non-polar lipids were separated by normal-phase HPLC into individual classes and the fraction of sterol esters was subsequently separated by reversed-phase HPLC into intact molecular species. Further separation and identification of the fractions after HPLC were effected by capillary gas chromatography-mass spectrometry (cGC-MS) with positive and/or negative chemical ionization. A technique consisting of direct injection of the sample after its passage through the detector into the on-column injector of the gas chromatograph was used to transfer the sample from HPLC-HPLC to cGC-MS. By means of this method it was possible to demonstrate more than 30 sterols in both the alga and the yeast, and more than 20 new sterol esters were detected.

Chlorophyta↗
PubMed1979

Side chain-hydroxylated sterols of the red alga Asparagopsis armata: significant products or artifacts due to autoxidation?

Sterols characterized by an allylic hydroxyl group in the side chain, such as stigmasta-5,28-diene-3 beta, 24 epsilon-diol (1), cholesta-5,23-diene-3 beta,25-diol (2) and cholesta-5,25-diene-3 beta,24 epsilon-diol (3), have been identified several times in various marine algae. Their origin was considered as doubtful: they could have been bona fide constituents of the alga, or be artifacts caused by autoxidation during the isolation process. We have shown that the dihydroxy steroids 2 and 3 can indeed be produced by the autoxidation of cholesta-5,24-dien-3 beta-ol (desmosterol) (5), but that they are nevertheless present in the taxonomic significance.

Cholestadienols↗
PubMed1994

Poisoning by the red alga 'ogonori' (Gracilaria verrucosa) on the Nojima Coast, Yokohama, Kanagawa Prefecture, Japan.

A food poisoning case due to the ingestion of 'ogonori', an edible red alga, occurred at Yokohama, Kanagawa Prefecture, Japan, in late October 1993, resulting in two victims, including one death (female). No causative agent present in the ogonori was found from a routine bioassay for marine toxins. From the production of increased amounts of prostaglandins (PGs), mainly PGE2, by the alga on stimulation by cutting or soaking in fresh water, and further increase of PGE2 by addition of arachidonic acid, it appeared that an enzyme, probably fatty acid cyclooxygenase, in the ogonori and the body of the victim, was acting on the highly unsaturated fatty acids in the oil of the ingested seafood and in the blood hemorrhaged from the stomach of the victim. This resulted in the production of over 30 mg of PGE2 and small amounts of other PGs in a comparatively short time. With this dosage the victim suffered from nausea, vomiting, and hypotension, and died of hypotensive shock. PGE2 seems to work more selectively on females. This type of poisoning is very unusual, and differs from the more familiar forms of poisoning occurring after ingestion of marine organisms.

Animals↗
PubMed1996

Determination of bioconcentration potential of tetrachloroethylene in marine algae by 13C.

The use of stable isotope of organic-carbon, organic-13C, as a tracer for the determination of the concentration of tetrachloroethylene (PCE), CA, in Heterosigma akashiwo and Skeletonema costatum was examined. CA determined by the 13C and GC methods showed good agreement with each other. This suggests that it is reasonable and reliable to determine the bioconcentration potential of PCE in marine algae. Fitting values of bioconcentration potential parameters, including uptake rate constant k1, elimination rate constant k2 and bioconcentration factor on the basis of dry weight BCFD, were done not only to the time course for PCE uptake by the algae with the bioconcentration model, but also to experimental data for "percent inhibition(%) approximately exposure concentration of PCE approximately time" with the combined bioconcentration and probability model. The values obtained from the bioconcentration model were consistent with those from the combined bioconcentration and probability model. With the parameters (such as k1, k2, growth rate constant kG, critical concentration of HOCs in the organism resulting in growth inhibition CA* and spread factor S) the variability in toxicity (such as EC10, EC50, EC70) can be estimated from the combined bioconcentration and probability model, which fits well with the experimental observations.

Carbon Radioisotopes↗
PubMed1985

Lectins and lectin-like molecules in lower plants. II. Freshwater algae.

Freshwater chlamydomonad algae possess flagella surface isoagglutinins of a glycoprotein nature which are involved in gamete recognition and consequent cell fusion. Alternatively, such molecules may have a receptor role in certain Chlamydomonas species. In some freshwater volvocaines, lectin-like substances act as inducers of sexuality. At the moment it is speculative whether these materials can serve as naturally-occurring antibodies to protect algae from environmental antigens.

Chlamydomonas↗
PubMed1985

Lectins and lectin-like molecules in lower plants. I. Marine algae (review).

Marine algae possess agglutinins, generally of unknown carbohydrate specificity, against a diverse array of erythrocytes but in a small number of species these haemagglutinins react with certain human blood group types. In seaweeds, lectins or lectin-like molecules are involved in gamete recognition and consequent reproductive cell fusion. Although some substances produced by algae are antiviral, antifungal, antibacterial, haemolytic and toxic, no similarity to mammalian immunoglobulins either structurally or physico-chemically has been observed for algal agglutinins. Whether such compounds have a defence or immune function and perform an antibody-like role to enable algal species to survive and counteract infections within their environment remains tentative.

Eukaryota↗
PubMed1983

Interest of dynamic tests in acute ecotoxicity assessment in algae.

Sorption of toxics by algae may be important and occurs very early. Thus, a decrease of the experimental toxic concentrations in the medium results in understating toxicity when tests are conducted under static conditions. In this work, two different methods of exposure of algae (Chlorella vulgaris) are studied, the static test and the pseudodynamic test. Acute effects (biological and analytical effects) of inorganic compounds (Cu2+, Cd2+, Pb2+, Cr6+) have been evaluated for 96 hr of exposure; in each case, IC50 is much lower in the dynamic condition than in the static one. The percentage of reduction varies from 55 to 75% after 96 hr. Accumulation of metal by chlorellae is greater when testing by the pseudodynamic way, with Cu2+ and Pb2+. But in the case of Cd2+ and Cr6+, the concentration factors are similar in the two kinds of exposure. These results point out the advantage of the pseudodynamic test, of which the methodology is very easy, for a more realistic assessment of acute ecotoxicity in these organisms.

Cadmium↗
PubMed1987

Responses of marine unicellular algae to brominated organic compounds in six growth media.

Marine unicellular algae, Skeletonema costatum, Thalassiosira pseudonana, and Chlorella sp. were exposed to the industrial brominated compounds tetrabromobisphenol A, decabromobiphenyloxide (DBBO), hexabromocyclododecane (HBCD), pentabromomethylbenzene (PBMB), pentabromoethylbenzene (PBEB), and the herbicide bromoxynil (BROM), in six algal growth media. High concentrations of DBBO (1 mg liter-1), PBMB (1 mg liter-1), and PBEB (0.5 mg liter-1) reduced growth by less than 50%. EC50s of the other compounds varied with growth medium, with high EC50/low EC50 ratios between 1.3 and 9.9. Lowest EC50s, 9.3 to 12.0 micrograms liter-1, were obtained with S. costatum and HBCD. It is concluded that responses to toxicants in different media are the results of interactions among algae, growth medium, toxicant, and solvent carrier.

Eukaryota↗
PubMed1990

Chronic toxicities of surfactants and detergent builders to algae: a review and risk assessment.

Surfactants are high volume chemicals used primarily in detergent products and are found in natural waters. The toxic effects of representative surfactants on aquatic life have been determined and summarized in greater detail for animal test species than for aquatic vegetation. This paper summarizes the chronic toxicity levels for algae, an important trophic level in aquatic ecosystems. Toxic effects have been determined for a few commercially important surfactants and primarily for cultured freshwater algae under the controlled conditions of the laboratory where inhibition, and in some cases, stimulation have been observed. The reported toxicities of surfactants have varied widely over several orders of magnitude and the effect levels are compound and species-specific. Species sensitivity can vary as much as three orders of magnitude to the same surfactant and the effects of different surfactants on the same algal species can vary as much as four orders of magnitude. Therefore, data generalizations and extrapolations are difficult but anionic and nonionic surfactants and detergent builders are relatively non-toxic when compared to various cationic monoalkyl and dialkyl quaternary ammonium salts. Recent toxicity studies conducted in the field monitoring the effects of several surfactants used in commercial products on various structural and functional parameters of natural algal communities have shown toxicity to be less in many cases than that predicted from laboratory tests. Furthermore, the field-derived effect levels typically exceed the reported measured environmental levels of the corresponding surfactants indicating the likelihood of no impact. Additional field studies are needed to substantiate this trend for these and other commercially important surfactants particularly for natural saltwater algal assemblages for which the toxicity data base is unavailable.

Detergents↗
PubMed1992

Frozen algae as food for Daphnia magna Straus in toxicity testing.

As EC validity criteria for the production of Daphnia magna neonates in standard toxicity tests set fecundity minima which must be attained, it is important that culture conditions provide an adequate ration of high quality food. Maintaining a steady supply of fresh algae can be problematical so the possibility of using frozen food was investigated. The performance of three generations of D. magna fed on diets of fresh or frozen Chlorella was compared. There were no significant effects on fecundity due to food type or generation. Cumulative fecundity (over 21 days) on fresh or frozen food exceeded 120 neonates per female and satisfied that EC validity criterion (60 neonates per female). In addition criteria relating to survival and variability were met. We conclude that frozen Chlorella are an acceptable substitute for fresh algae.

Animals↗
PubMed1991

Studies of the effect on tumor and normal cells in vitro with bioactive materials isolated from algae by a microcalorimetric method.

Recently much attention has been focused on the human physiological actions with bioactive materials from algae to enhance immunocompetence and to strengthen antineoplastic activity. In the study reported in this paper an MS 80 standard Calvet microcalorimeter was used for measuring the thermogram of HeLa, human breast carcinoma (Bcap-37) and diploid fibroblasts from human feral lung (2BS) under conditions with or without the presence of bioactive materials (Sp) from algae. At the same time, the cell number was counted, the inhibition rate of growth and the death rate were obtained. It has been shown that the Sp (100 micrograms/ml) was the growth inhibitor and lethal to tumor cells (Bcap-37 and HeLa), but had no influence on the normal (2BS) cells under the same conditions in vitro.

Biological Factors↗
PubMed1995

Characterization of the polyubiquitin gene in the marine red alga Gracilaria verrucosa.

We have cloned a nuclear gene (UBI6R) and corresponding cDNAs that encode polyubiquitin in the florideophycidean red alga Gracilaria verrucosa. The gene encodes a polyubiquitin composed of six tandem ubiquitin units, followed by a single glutamine residue. The deduced amino acid sequences are identical among all six units, and identical to the ubiquitin of the florideophyte Aglaothamnion neglectum. There is high sequence similarity among the red algal ubiquitins and those of animals, green plants, fungi and several protists. Only one polyubiquitin gene was found by Southern hybridization analysis of G. verrucosa nuclear DNA. The upstream region of the gene is rich in putative cis-acting transcription-regulatory elements, including a putative heat-responsive element. Poly(A) addition to UBI6R mRNA was observed in cDNAs at four different sites, implicating the sequences AATAAA and (or) AGTAAA as poly(A) addition signals. The polyubiquitin genes of red algae show features of concerted evolution, but appear to be subject to less sequence homogenization than those of animals.

Amino Acid Sequence↗
PubMed1988

Auxin induced stress tolerance in algae.

IAA effect on responses of West African algae Caloglosa, Bostrychia, Rhizoclonium and the fresh water alga Pithophora to different growth conditions was examined in growth chamber experiments. The auxin (2.28 x 10(-5) M) caused growth increase of 2.3- and 2.6-fold in Caloglossa and 1.6 and 1.7 in Rhizoclonium, respectively, in sea water and 1:1 diluted sea water/Erdschreiber medium. In Bostrychia pronounced deterioration of growth was noticed in the control samples between 16 and 32 days in culture. The cultures maintained an active growth, however, in the presence of IAA. IAA also allowed Pithophora to withstand salinity: Compared to growth in fresh water, a 65% growth inhibition was recorded in 1:1 diluted sea water in the absence of auxin and a slight growth stimulation when the auxin was present. Pithophora and Rhizoclonium also maintained higher rates of growth in extremal temperatures of 10 and 45 degrees C when the auxin was present.

Journal Article↗
PubMed1995

Toxicity to Microtox, micro-algae and duckweed of effluents from the Bai Bang paper company (BAPACO), a Vietnamese bleached kraft pulp and paper mill.

Toxicity of the combined effluent as well as effluents from different production units of BAPACO, a Vietnamese bleached kraft integrated pulp and paper mill, was studied using three ecotoxicological tests: Microtox, the micro-alga, Selenastrum capricornutum, and the duckweed, Lemna aequinoctialis. Physico-chemical characteristics of the effluents were also analyzed. Due to unstable operating conditions of the mill, a number of samples taken at different monitoring periods from each effluent were tested, in order to get statistically reliable ranges and averages of toxicity characteristics. For the mill combined effluent, it was found that the micro-algae were the most sensitive followed by Microtox bacteria, while duckweed was not sensitive. Microtox tests showed that the bleaching filtrate from the chlorination stage (C-stage) was the most toxic among all effluents in the mill. The combined effluent from the bleaching plant contributed the largest TEF (Toxicity Emission Factor) to the toxicity balance of the whole BAPACO combined effluent. A less-than-additive mode of toxicity was obtained. In spite of high pollution loads, e.g. BOD, COD, SS, to the Red River, the toxicity of the effluent was considered to be low. However, during periods of low river water sublethal toxic effects on the biota may be expected.

Journal Article↗
PubMed1983

Accidental release of fluoride into experimental pond and accumulation in sediments, plants, algae, molluscs and fish.

The fate of fluoride in a simulated accidental release into an experimental pond was observed for 30 days in Grenoble, France. The components investigated were water, sediments, plants, algae, molluscs, and fish. Twenty-four hours after the release, most (99.8%) of the fluoride was distributed in the physical components (water and sediments), and the biological agents contained only 0.2% of the fluoride released. Despite an exposure to hot spots of 5000 ppm at the beginning of the accidental release, no visible toxic effects were observed on the biological components such as plants, algae, molluscs, and fish. The effects of the physical components in the defluoridation showed a significant role in the control the accidental release of fluoride in the aquatic system.

Animals↗
PubMed1988

Tumor necrosis factor in experimental cancer regression with alphatocopherol, beta-carotene, canthaxanthin and algae extract.

Regression of established hamster buccal pouch carcinoma has recently been demonstrated in association with an induction of tumor necrosis factor alpha in macrophages. Regression of hamster buccal pouch tumors has also been demonstrated following the local injection of alphatocopherol, canthaxanthin and an extract of Spirulina-Dunaliella algae. The current study demonstrates that cancer regression is also accompanied by a significant induction of tumor necrosis factor in macrophages in the tumor area, suggesting a possible mechanism of tumor destruction. One hundred and forty young, male adult hamsters were divided into seven equal groups of 20 animals. Epidermoid carcinomas were induced in right buccal pouches by 14 weeks of painting, three times per week, of a 0.5% solution of 7,12-dimethylbenz(a)anthracene. Groups 1 and 2 were untreated and sham injected controls. Groups 3-7 had injected twice weekly into the right buccal pouches 0.1 ml (1.9 mg/ml of 13-cis-retinoic acid, canthaxanthin, algae extract, beta-carotene and alphatocopherol. After 4 weeks the tumors in groups 3-7 demonstrated varying degrees of regression and the animals were sacrificed and the right buccal pouches excised. Tumor necrosis factor alpha (TNF-alpha) was demonstrated by immunohistochemical techniques. A very significant increase in TNF-alpha positive macrophages was found in the tumor-bearing pouches of animals in groups 5-7. Smaller numbers of TNF-alpha-positive macrophages were found in group 4 pouches and a very slight increase in group 3 pouches.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1985

The nature of the ancestral red alga: inferences from a cladistic analysis.

A cladistic analysis of the orders of Rhodophyta is presented. Sixteen taxa and 34 characters comprise the data matrix. Included in the analysis are biochemical and ultrastructural features of pigments, cell walls, cell organelles, mitosis and pit connections as well as vegetative and reproductive characters. The traditional recognition of two classes or subclasses, Bangiophycidae and Florideophycidae, is not supported regardless of whether Porphyridiales, Rhodochaetales or Bangiales is designated the outgroup. Florideophycidae, however, appears to be monophyletic with Bangiales as its sister group. Relationships among taxa with one or two plug cap layers, i.e. Acrochaetiales, Palmariales, Corallinales, Nemaliales, Batrachospermales, Gelidiales and Hildenbrandiales are unresolved. Rhodochaetales, Bangiales and possibly Erythropeltidales are monophyletic, but Porphyridiales is polyphyletic. The class Cyanidiophyceae is not recognized and the included genera are considered to be unicellular red algae belonging to Porphyridiales. Taxa that have been proposed as sister groups for red algae, including Cyanobacteria, Cryptophyta, Glaucophyta and Chlorophyta, and Ascomycetes and Basidiomycetes are discussed in relation to the proposed phylogeny of Rhodophyta.

Models, Genetic↗