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At least 883 records · Page 49Linked to original sources
PubMed2003

Interactions between algae (Selenastrum capricornutum) and pesticides: implications for managing constructed wetlands for pesticide removal.

This laboratory study examined the interactions between an algal species found in wetlands (Selenastrum capricornutum) and two agricultural pesticides (atrazine and lindane). Pesticide additions had a positive effect on the chlorophyll a concentrations of the treatments. The presence of algae decreased the aqueous persistence of both pesticides. It is speculated that the algae either provided sites for pesticide sorption or facilitated pesticide degradation.

Adsorption↗
PubMed1965

Incorporation of H3-thymidine into chloroplast DNA of marine algae.

The chloroplasts of three genera of marine algae, Dictyota, Padina, and Bryopsis, were labeled with tritiated-thymidine for various time periods during culture in "Erd-Schreiber's" solution. Autoradiographs were prepared from both smeared and sectioned material. They revealed that almost all of the radioactivity was in the cytoplasm and associated with the chloroplasts, as detected in the overlying silver halide crystals. Deoxyribonuclease, ribonuclease, and hot trichloracetic acid treatments indicated that the loss of radioactivity corresponded to the removal of DNA and not RNA. Quantitative studies of silver grain distribution suggested that the radioactivity of the labeled DNA originated from the edge of the pyrenoids on either side in the longitudinal direction of Bryopsis chloroplasts. Nuclei did not incorporate H(3)-thymidine even though cells were dividing rapidly in the three genera examined. It is postulated that the enzyme, thymidine kinase, is absent as a coding sequence of nuclear DNA in algae, but is present in chloroplast DNA. When the chloroplasts of Dictyota and Padina in various stages of division were scored for labeling, there appeared to be a DNA synthesis period, analogous to S period in cell division. This chloroplast-labeling period occurred just previous to fission. Many of the criteria seem to have been satisfied to establish the self-reproducing and semi-autonomous nature of chloroplasts, especially when combined with the chemical, genetic, and morphological evidence.

Autoradiography↗
PubMed1974

Ultrastructure of mitosis and cytokinesis in the multinucleate green alga Acrosiphonia.

The processes of mitosis and cytokinesis in the multinucleate green alga Acrosiphonia have been examined in the light and electron microscopes. The course of events in division includes thickening of the chloroplast and migration of numerous nuclei and other cytoplasmic incusions to form a band in which mitosis occurs, while other nuclei in the same cell but not in the band do not divide. Centrioles and microtubules are associated with migrated and dividing nuclei but not with nonmigrated, nondividing nuclei. Cytokinesis is accomplished in the region of the band, by means of an annular furrow which is preceded by a hoop of microtubules. No other microtubules are associated with the furrow. Characteristics of nuclear and cell division in Acrosiphonia are compared with those of other multinucleate cells and with those of other green algae.

Cell Division↗
PubMed1960

The fine structure of the nuclear material of a blue-green alga, Anabaena cylindrica Lemm.

The chromatinic material of the blue-green alga Anabaena cylindrica has complex configurations in the central regions of the cells. The distribution of the chromatin within the cells varies in different filaments, probably in response to variations in the disposition of other cellular components. In electron micrographs of thin sections of organisms fixed by the method of Kellenberger, Ryter, and Séchaud (1958) the centroplasm contains fibrillar and possibly granular components which can be identified as the nuclear material by comparison with stained preparations viewed in the light microscope. The fibrils in the nuclear regions have diameters in the range of 5 to 7 mmicro and are embedded in a matrix of lower density. The nuclear regions are not greatly different from the cytoplasm in their electron density. Reducing the calcium content of the fixative results in coagulation of the fibrils to form coarser structures. The significance of the observations is discussed in relation to observations on the fine structure of other classes of algae and of bacteria.

Anabaena cylindrica↗
PubMed1976

Ion transport studies and determination of the cell wall elastic modulus in the marine alga Halicystis parvula.

Using cultured cells of the marine alga, Halicystis parvula, we measured the concentrations of 11 inorganic ions in the vacuolar sap and the electrical potential difference (PD) between the vacuole and the external solution. In normal cells under steady-state conditions a comparison of the electrochemical equilibrium (Nernst) potential for each ion with the PD of -82 mV (inside negative) indicates that Na+ and K+ are actively transported out of the vacuole whereas all anions are pumped into the cell. Although the [K+] in the vacuole is only 9 mM, the cytoplasmic [K+] is about 420 mM, which suggests that the outwardly directed pump is at the tonoplast. Using large Halicystis cells we perfused the vacuole with an artificial seawater and conducted a short-circuit analysis of ion transport. The short-circuit current (SCC) of 299 peq - cm-2-s-1 is not significantly different from the net influx of Cl-. There is a small, but statistically significant net efflux of K+ (less than 1 pmol-cm-2.-1), while the influx and efflux of Na+ are not significantly different. Therefore, the SCC is a good measure of the activity of the Cl- pump. Finally, we measured the volumetric elastic modulus (epsilon) of the cell wall by measuring the change in cell volume when the internal hydrostatic pressure was altered. The value of epsilon at applied pressures between 0 and 0.4 atm is about 0.6 atm, which is at least 100-fold lower than the values of epsilon for all other algae which have been studied.

Biological Transport, Active↗
PubMed2004

Localization of the blue-light receptor phototropin to the flagella of the green alga Chlamydomonas reinhardtii.

Blue light controls the sexual life cycle of Chlamydomonas, mediated by phototropin, a UV-A/blue-light receptor that plays a prominent role in multiple photoresponses. By using fractionation experiments and immunolocalization studies, this blue-light receptor, in addition to its known localization to the cell bodies, also was detected in flagella. Within the flagella, it was completely associated with the axonemes, in striking contrast to the situation in higher plants and the Chlamydomonas cell body where phototropin was observed in the plasma membrane. Its localization was not perturbed in mutants lacking several prominent structural components of the axoneme. This led to the conclusion that phototropin may be associated with the outer doublet microtubules. Analysis of a mutant (fla10) in which intraflagellar transport is compromised suggested that phototropin is a cargo for intraflagellar transport. The blue-light receptor thus seems to be an integral constituent of the flagella of this green alga, extending the list of organisms that harbor sensory molecules within this organelle to unicellular algae.

Animals↗
PubMed1991

Vitamin B-12 from algae appears not to be bioavailable.

The effect of algae (nori and spirulina) and fermented plant foods on the hematological status of vitamin B-12-deficient children was evaluated. Although rising plasma vitamin B-12 concentrations in children consuming only plant foods (0.1-2.7 micrograms vitamin B-12/d) indicated that the vitamin B-12 was absorbed, elevated baseline values of mean corpuscular volume (MCV) further deteriorated. In contrast, MCV improved in children receiving fish containing 0.15-0.5 microgram vitamin B-12/d or a vitamin B-12 supplement. Further studies on the specificity of current vitamin B-12 assays are warranted. It seems unjustified to advocate algae and other plant foods as a safe source of vitamin B-12 because its bioavailability is questionable.

Animals↗
PubMed2005

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↗
PubMed2006

XET activity is found near sites of growth and cell elongation in bryophytes and some green algae: new insights into the evolution of primary cell wall elongation.

BACKGROUND AND AIMS: In angiosperms xyloglucan endotransglucosylase (XET)/hydrolase (XTH) is involved in reorganization of the cell wall during growth and development. The location of oligo-xyloglucan transglucosylation activity and the presence of XTH expressed sequence tags (ESTs) in the earliest diverging extant plants, i.e. in bryophytes and algae, down to the Phaeophyta was examined. The results provide information on the presence of an XET growth mechanism in bryophytes and algae and contribute to the understanding of the evolution of cell wall elongation in general. METHODS: Representatives of the different plant lineages were pressed onto an XET test paper and assayed. XET or XET-related activity was visualized as the incorporation of fluorescent signal. The Physcomitrella genome database was screened for the presence of XTHs. In addition, using the 3' RACE technique searches were made for the presence of possible XTH ESTs in the Charophyta. KEY RESULTS: XET activity was found in the three major divisions of bryophytes at sites corresponding to growing regions. In the Physcomitrella genome two putative XTH-encoding cDNA sequences were identified that contain all domains crucial for XET activity. Furthermore, XET activity was located at the sites of growth in Chara (Charophyta) and Ulva (Chlorophyta) and a putative XTH ancestral enzyme in Chara was identified. No XET activity was identified in the Rhodophyta or Phaeophyta. CONCLUSIONS: XET activity was shown to be present in all major groups of green plants. These data suggest that an XET-related growth mechanism originated before the evolutionary divergence of the Chlorobionta and open new insights in the evolution of the mechanisms of primary cell wall expansion.

Amino Acid Sequence↗
PubMed1996

Shewanella alga bacteremia in two patients with lower leg ulcers.

The first Danish cases of Shewanella alga bacteremia in two patients with chronic lower leg ulcers are reported. Both patients were admitted to the hospital during the same month of a very warm summer and had been exposed to the same marine environment, thereby suggesting the same source of infection. Both patients survived; however, one of them had extensive myonecrosis, while the other patient had an uncomplicated course. The strains were initially believed to be Shewanella putrefaciens on the basis of key characteristics and results of the API 20NE identification system (bioMérieux, Marcy l'Etoile, France), but further genetic and physiological analyses identified them as Shewanella alga.

Aged↗
PubMed2002

Bactericidal activity of phlorotannins from the brown alga Ecklonia kurome.

The bactericidal activity of phlorotannins from brown algae against food-borne pathogenic bacteria (25 strains), methicillin-resistant Staphylococcus aureus (MRSA) (nine strains) and Streptococcus pyogenes (one strain) was examined and compared with that of catechins. In addition, the effect of the oral administration of phlorotannins on mice was investigated. Phlorotannins, which are oligomers of phloroglucinol, were extracted from thalli of the brown alga Ecklonia kurome and prepared by silicic acid chromatography. The bactericidal activity of polyphenols was determined using a broth microdilution method. Of the bacteria tested, Campylobacter spp. were the most susceptible to the phlorotannins. The MBCs of the crude phlorotannins, dieckol and 8,8'-bieckol (hexamers), and that of epigallocatechin gallate (EGCG) against Campylobacter jejuni were 50 mg/L, 0.03 micromol/mL and 0.03 micromol/mL, respectively. On the whole, the bactericidal effects of the phlorotannins were more pronounced than those of the catechins. The phlorotannins were as effective against MRSA as against the other bacteria tested. At twice the MBCs, all Vibrio parahaemolyticus were killed within 0.5-2 h. However, at the same concentration, catechins showed little bactericidal activity within 4 h. No effect on mice was observed with oral administration of the phlorotannins under the conditions tested.

Animals↗
PubMed2004

The complete mitochondrial DNA sequence of the green alga Pseudendoclonium akinetum (Ulvophyceae) highlights distinctive evolutionary trends in the chlorophyta and suggests a sister-group relationship between the Ulvophyceae and Chlorophyceae.

The mitochondrial genome has undergone radical changes in both the Chlorophyta and Streptophyta, yet little is known about the dynamics of mtDNA evolution in either of these lineages. In the Chlorophyta, which comprises four of the five recognized classes of green algae (Prasinophyceae, Trebouxiophyceae, Ulvophyceae, and Chlorophyceae), the mitochondrial genome varies from 16 to 55 kb. This genome has retained a compact gene organization and a relatively complex gene repertoire ("ancestral" pattern) in the basal lineages represented by the Trebouxiophyceae and Prasinophyceae, whereas it has been reduced in size and gene complement and tends to evolve much more rapidly at the sequence level ("reduced-derived" pattern of evolution) in the Chlorophyceae and the lineage leading to the enigmatic chlorophyte Pedinomonas. To gain information about the evolutionary trends of mtDNA in the Ulvophyceae and also to gain insights into the phylogenetic relationships between ulvophytes and other chlorophytes, we have determined the mtDNA sequence of Pseudendoclonium akinetum. At 95,880 bp, Pseudendoclonium mtDNA is the largest green-algal mitochondrial genome sequenced to date and has the lowest gene density. These derived features are reminiscent of the "expanded" pattern exhibited by embryophyte mtDNAs, indicating that convergent evolution towards genome expansion has occurred independently in the Chlorophyta and Streptophyta. With 57 conserved genes, the gene repertoire of Pseudendoclonium mtDNA is slightly smaller than those of the prasinophyte Nephroselmis olivacea and the trebouxiophyte Prototheca wickerhamii. This ulvophyte mtDNA contains seven group I introns, four of which have homologs in green-algal mtDNAs displaying an "ancestral" or a "reduced-derived" pattern of evolution. Like its counterpart in the chlorophycean green alga Scenedesmus obliquus, it features numerous small, dispersed repeats in intergenic regions and introns. Its overall rate of sequence evolution appears to be accelerated to an intermediary level as compared with the rates observed in "ancestral" and "reduced-derived" mtDNAs. In agreement with the finding that Pseudendoclonium mtDNA exhibits features typical of both the "ancestral" and "reduced-derived" patterns of evolution, phylogenetic analyses of seven mtDNA-encoded proteins revealed a sister-group relationship between this ulvophyte and chlorophytes displaying "reduced-derived" mtDNAs.

Base Sequence↗
PubMed1996

Nuclear-encoded rDNA group I introns: origin and phylogenetic relationships of insertion site lineages in the green algae.

Group I introns are widespread in eukaryotic organelles and nuclear-encoded ribosomal DNAs (rDNAs). The green algae are particularly rich in rDNA group I introns. To better understand the origins and phylogenetic relationships of green algal nuclear-encoded small subunit rDNA group I introns, a secondary structure-based alignment was constructed with available intron sequences and 11 new subgroup ICI and three new subgroup IB3 intron sequences determined from members of the Trebouxiophyceae (common phycobiont components of lichen) and the Ulvophyceae. Phylogenetic analyses using a weighted maximum-parsimony method showed that most group I introns form distinct lineages defined by insertion sites within the SSU rDNA. The comparison of topologies defining the phylogenetic relationships of 12 members of the 1512 group I intron insertion site lineage (position relative to the E. coli SSU rDNA coding region) with that of the host cells (i.e., SSU rDNAs) that contain these introns provided insights into the possible origin, stability, loss, and lateral transfer of ICI group I introns. The phylogenetic data were consistent with a viral origin of the 1512 group I intron in the green algae. This intron appears to have originated, minimally, within the SSU rDNA of the common ancestor of the trebouxiophytes and has subsequently been vertically inherited within this algal lineage with loss of the intron in some taxa. The phylogenetic analyses also suggested that the 1512 intron was laterally transferred among later-diverging trebouxiophytes; these algal taxa may have coexisted in a developing lichen thallus, thus facilitating cell-to-cell contact and the lateral transfer. Comparison of available group I intron sequences from the nuclear-encoded SSU rDNA of phycobiont and mycobiont components of lichens demonstrated that these sequences have independent origins and are not the result of lateral transfer from one component to the other.

Base Sequence↗
PubMed1993

Evidence for independent acquisition of group I introns in green algae.

We report the occurrence of a group I intron, 452 nucleotides in length, in the nuclear small-subunit ribosomal gene of the benthic seaweed Urospora penicilliformis, a member of the green algal class Ulvophyceae. Group I introns have been reported in fungi, myxomycetes, the ciliate genus Tetrahymena, and recently in five unicellular chlorophycean algae. The sequence of the conserved core of the U. penicilliformis group I intron was aligned with that of 15 other introns of this type, and the evolutionary relationships among these introns were examined. Comparison of the "intron" tree with phylogenetic hypotheses of the intron-harboring organisms shows that nuclear group I introns in green algae have arisen several times and are not lineage specific.

Animals↗
PubMed1999

Two types of ftsZ genes isolated from the unicellular primitive red alga Galdieria sulphuraria.

FtsZ plays a crucial role in bacterial cell division, and may be involved in plastid division in eukaryotes. To investigate the evolution of the dividing apparatus from prokaryotes to eukaryotes, the ftsZ genes were isolated from the unicellular primitive red alga Galdieria sulphuraria. Two ftsZ genes (GsftsZ1 and GsftsZ2) were isolated. This suggests that duplication and divergence of the ftsZ gene occurred in an early stage of plant evolution. A comparison of the FtsZs of G. sulphuraria and other organisms shows that FtsZ is highly and universally conserved among prokaryotes, primitive eukaryotic algae, and higher plants. The GsftsZ2 gene seems to contain an intron. Southern hybridization analysis of the G. sulphuraria chromosomes separated by CHEF revealed that each ftsZ gene and its flanking region may be duplicated.

Amino Acid Sequence↗
PubMed2002

Nitric oxide production mediated by nitrate reductase in the green alga Chlamydomonas reinhardtii: an alternative NO production pathway in photosynthetic organisms.

Biological activity of nitric oxide (NO) production was investigated in the unicellular green alga Chlamydomonas reinhardtii. An NO specific electrode detected a rapid increase in signal when nitrite (NO(2)(-)) was added into a suspension of C. reinhardtii intact cells in the dark. The addition of KCN or the NO quencher bovine hemoglobin completely abolished the signal, verifying that the nitrite-dependent increase in signal is due to enzymatic NO production. L-arginine, the substrate for NO synthase, did not induce detectable NO production and the NOS inhibitor N(omega)-nitro-L-arginine showed no inhibitory effect on the nitrite-dependent production of NO. Illuminating cells showed a significant suppressive effect on NO production. When the photosynthetic electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea was present in the suspension, C. reinhardtii cells produced NO after the addition of nitrite even under illumination. Kinetic and microscopic observations, using the intracellular fluorescent NO probe 4,5-diaminofluorescein-2 diacetate, both demonstrated that NO was produced within the cells in response to the addition of nitrite. The Chlamydomonas mutant cc-2929, which lacks nitrate reductase (NR) activity, did not display any of the responses observed in the wild-type cells. The results presented here provide direct in vivo evidence to confirm that NR is involved in the nitrite-dependent NO production in the green alga.

Animals↗
PubMed2004

Natural protein engineering: a uniquely salt-tolerant, but not halophilic, alpha-type carbonic anhydrase from algae proliferating in low- to hyper-saline environments.

Dunaliella salina is a unicellular green alga thriving in environments ranging from fresh water to hyper-saline lakes, such as the Dead Sea. An unusual, internally duplicated, 60 kDa alpha-type carbonic anhydrase (dCA I), located on the surface of this alga, is expected to function over a broad range of salinities. It would therefore differ from other carbonic anhydrases that already lose activity at low salinities and also from halophilic proteins that require high salinities for conformational stability. Enzymatic analyses indeed indicated that dCA I retained activity at salt concentrations ranging from low salt to at least 1.5 M NaCl or KCl for CO(2) hydration, 2.0 M NaCl for esterase activity and 0.5 M for bicarbonate dehydration. Although measurements at higher salinities were constrained by the interference of salt in the respective assayed reactions, activity was noticeable even at 4.0 M NaCl. Comparisons of the internally duplicated dCA I to single-domain derivatives indicated that inter-domain interactions played a decisive role in the stability, activity, salt tolerance and pH responses of dCA I. Hence dCA I is a uniquely salt- tolerant protein, retaining an active conformation over a large range of salinities and, as a Zn metalloenzyme, largely immune to the specific inhibitory effects of anions. Its unique features make dCA I a useful model to understand the physico-chemical basis of halotolerance and protein-salt interactions in general.

Amino Acid Sequence↗
PubMed1992

Anticoagulants from marine algae.

Anticoagulant properties were first described in extracts from marine algae over 50 years ago. Currently over 60 species, representing the three major divisions of marine algae, have been reported to have such properties. The major active components are a variety of sulphated polysaccharides, some of which characterize as proteoglycans. These sulphated polysaccharides/proteoglycans exert antithrombin properties, primarily mediated by heparin cofactor II (HCII). However antithrombin III (ATIII) mediated anticoagulant activities, as well as an element of direct antithrombin activity, have also been observed.

Amino Acid Sequence↗