PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Chlorophyta”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2005

Adaptation of Spirogyra insignis (Chlorophyta) to an extreme natural environment (sulphureous waters) through preselective mutations.

Adaptation of Spirogyra insignis (Chlorophyceae) to growth and survival in an extreme natural environment (sulphureous waters from La Hedionda Spa, S. Spain) was analysed by using an experimental model. Photosynthesis and growth of the alga were inhibited when it was cultured in La Hedionda Spa waters (LHW), but after further incubation for several weeks, the culture survived due to the growth of a variant that was resistant to LHW. A Luria-Delbruck fluctuation analysis was carried out to distinguish between resistant filaments arising from rare spontaneous mutations and resistant filaments arising from other mechanisms of adaptation. It was demonstrated that the resistant filaments arose randomly by rare spontaneous mutations before the addition of LHW (preselective mutations). The rate of spontaneous mutation from sensitivity to resistance was 2.7 x 10(-7) mutants per cell division. Since LHW(resistant) mutants have a diminished growth rate, they are maintained in nonsulphureous natural waters as the result of a balance between new resistants arising from spontaneous mutation and resistants eliminated by natural selection. Thus, recurrence of rare spontaneous preselective mutations ensures the survival of the alga in sulphureous waters.

Adaptation, Physiological↗
PubMed2006

Cladophora (Chlorophyta) spp. harbor human bacterial pathogens in nearshore water of Lake Michigan.

Cladophora glomerata, a macrophytic green alga, is commonly found in the Great Lakes, and significant accumulations occur along shorelines during the summer months. Recently, Cladophora has been shown to harbor high densities of the fecal indicator bacteria Escherichia coli and enterococci. Cladophora may also harbor human pathogens; however, until now, no studies to address this question have been performed. In the present study, we determined whether attached Cladophora, obtained from the Lake Michigan and Burns Ditch (Little Calumet River, Indiana) sides of a breakwater during the summers of 2004 and 2005, harbored the bacterial pathogens Shiga toxin-producing Escherichia coli (STEC), Salmonella, Shigella, and Campylobacter. The presence of potential pathogens and numbers of organisms were determined by using cultural methods and by using conventional PCR, most-probable-number PCR (MPN-PCR), and quantitative PCR (QPCR) performed with genus- and toxin-specific primers and probes. While Shigella and STEC were detected in 100% and 25%, respectively, of the algal samples obtained near Burns Ditch in 2004, the same pathogens were not detected in samples collected in 2005. MPN-PCR and QPCR allowed enumeration of Salmonella in 40 to 80% of the ditch- and lakeside samples, respectively, and the densities were up to 1.6 x 10(3) cells per g Cladophora. Similarly, these PCR methods allowed enumeration of up to 5.4 x 10(2) Campylobacter cells/g Cladophora in 60 to 100% of lake- and ditchside samples. The Campylobacter densities were significantly higher (P < 0.05) in the lakeside Cladophora samples than in the ditchside Cladophora samples. DNA fingerprint analyses indicated that genotypically identical Salmonella isolates were associated with geographically and temporally distinct Cladophora samples. However, Campylobacter isolates were genetically diverse. Since animal hosts are thought to be the primary habitat for Campylobacter and Salmonella species, our results suggest that Cladophora is a likely secondary habitat for pathogenic bacteria in Lake Michigan and that the association of these bacteria with Cladophora warrants additional studies to assess the potential health impact on beach users.

Campylobacter↗
PubMed2003

Occurrence of Escherichia coli and enterococci in Cladophora (Chlorophyta) in nearshore water and beach sand of Lake Michigan.

Each summer, the nuisance green alga Cladophora (mostly Cladophora glomerata) amasses along Lake Michigan beaches, creating nearshore anoxia and unsightly, malodorous mats that can attract problem animals and detract from visitor enjoyment. Traditionally, elevated counts of Escherichia coli are presumed to indicate the presence of sewage, mostly derived from nearby point sources. The relationship between fecal indicator bacteria and Cladophora remains essentially unstudied. This investigation describes the local and regional density of Escherichia coli and enterococci in Cladophora mats along beaches in the four states (Wisconsin, Illinois, Indiana, and Michigan) bordering Lake Michigan. Samples of Cladophora strands collected from 10 beaches (n = 41) were assayed for concentrations of E. coli and enterococci during the summer of 2002. Both E. coli and enterococci were ubiquitous (up to 97% occurrence), with overall log mean densities (+/- standard errors) of 5.3 (+/- 4.8) and 4.8 (+/- 4.5) per g (dry weight). E. coli and enterococci were strongly correlated in southern Lake Michigan beaches (P < 0.001, R(2) = 0.73, n = 17) but not in northern beaches (P = 0.892, n = 16). Both E. coli and enterococci survived for over 6 months in sun-dried Cladophora mats stored at 4 degrees C; the residual bacteria in the dried alga readily grew upon rehydration. These findings suggest that Cladophora amassing along the beaches of Lake Michigan may be an important environmental source of indicator bacteria and call into question the reliability of E. coli and enterococci as indicators of water quality for freshwater recreational beaches.

Chlorophyta↗
PubMed2004

Accurate and robust phylogeny estimation based on profile distances: a study of the Chlorophyceae (Chlorophyta).

BACKGROUND: In phylogenetic analysis we face the problem that several subclade topologies are known or easily inferred and well supported by bootstrap analysis, but basal branching patterns cannot be unambiguously estimated by the usual methods (maximum parsimony (MP), neighbor-joining (NJ), or maximum likelihood (ML)), nor are they well supported. We represent each subclade by a sequence profile and estimate evolutionary distances between profiles to obtain a matrix of distances between subclades. RESULTS: Our estimator of profile distances generalizes the maximum likelihood estimator of sequence distances. The basal branching pattern can be estimated by any distance-based method, such as neighbor-joining. Our method (profile neighbor-joining, PNJ) then inherits the accuracy and robustness of profiles and the time efficiency of neighbor-joining. CONCLUSIONS: Phylogenetic analysis of Chlorophyceae with traditional methods (MP, NJ, ML and MrBayes) reveals seven well supported subclades, but the methods disagree on the basal branching pattern. The tree reconstructed by our method is better supported and can be confirmed by known morphological characters. Moreover the accuracy is significantly improved as shown by parametric bootstrap.

Animals↗
PubMed1984

Hemichloris antarctica, gen. et sp. nov. (Chlorococcales, Chlorophyta), a cryptoendolithic alga from Antarctica.

Hemichloris antarctica gen. et sp. nov. (Oocystaceae, Chlorococcales) is characterized by a single, articulated, pyrenoid-less, thick saucer-shaped chloroplast, which generally fills less than half of the cell periphery. Multiplication is only by autospores. The species is psychrophilic and is damaged at temperatures above 20 degree C. Hemichloris antarctica is a member of the cryptoendolithic microbial community living in porous sandstone rocks of the Antarctica cold desert. It inhabits the zone below that of cryptoendolithic lichens and survives at extremely low light intensities. In the natural habitat, morphology is somewhat different from that in culture, as chloroplasts are smaller and without articulation, and the cells develop a gelatinous sheath.

Antarctic Regions↗
PubMed2004

Phylogenetic placement of "zoochlorellae" (Chlorophyta), algal symbiont of the temperate sea anemone Anthopleura elegantissima.

At northern latitudes the sea anemones Anthopleura elegantissima and its congener A. xanthogrammica contain unidentified green chlorophytes (zoochlorellae) in addition to dinophytes belonging to the genus Symbiodinium. This dual algal symbiosis, involving members of distinct algal phyla in one host, has been extensively studied from the perspective of the ecological and energetic consequences of hosting one symbiotic type over the other. However, the identity of the green algal symbiont has remained elusive. We determined the phylogenetic position of the marine zoochlorellae inhabiting A. elegantissima by comparing sequence data from two cellular compartments, the nuclear 18S ribosomal RNA gene region and the plastid-encoded rbcL gene. The results support the inclusion of these zoochlorellae in a clade of green algae that form symbioses with animal (Anthopleura elegantissima), fungal (the lichen genus Nephroma), and seed plant (Ginkgo) partners. This clade is distinct from the Chlorella symbionts of Hydra. The phylogenetic diversity of algal hosts observed in this clade indicates a predisposition for this group of algae to participate in symbioses. An integrative approach to the study of these algae, both within the host and in culture, should yield important clues about how algae become symbionts in other organisms.

Animals↗
PubMed2001

Genetic polymorphism in eight Chilean strains of the carotenogenic microalga Dunaliella salina Teodoresco (Chlorophyta).

Eight Chilean strains of Dunaliella salina obtained within a restricted geographic range, but exhibiting a high variability in their morphology, rate of growth and carotenogenic capacity, were analyzed by Random Amplified Polymorphic DNA (RAPD-PCR) Twenty of the 50 random primers (D, P, OPA and OPD series) that were tested amplified reproducible bands and were useful for comparative analysis of the strains. Of 107 polymorphic genetic markers, 49 were strain-specific. A great genetic variability was found among the strains in spite of their geographic proximity. In addition, phenetic analysis of the data showed close agreement between the morphophysiological attributes and the genetic diversity of the strains.

Base Sequence↗
PubMed2003

Effect of salinity on the quantity and quality of carotenoids accumulated by Dunaliella salina (strain CONC-007) and Dunaliella bardawil (strain ATCC 30861) Chlorophyta.

Dunaliella salina and D. bardawil are well-known microalgae accumulating high levels of beta-carotene under growth-limiting conditions. In both taxa, this pigment is primarily composed of the isomers 9-cis and all-trans. The 9-cis beta-carotene occurs only in natural sources and is the most attractive from a commercial point of view. The conditions that enhance the preferred accumulation of 9-cis beta-carotene in D. salina are controversial and they have not been well established yet. This study examined the effect of salinity on the quantity and quality of total carotenoids and beta-carotene isomers accumulated by D. salina (strain CONC-007) and D. bardawil (strain ATCC 30861) grown in two media with different nutritional compositions (PES and ART) and at salt concentrations of 1M, 2M and 3M NaCl. Total carotenoids were determined by spectrophotometry and beta-carotene isomers, by HPLC. The highest carotenoid contents per cell were obtained at 2M NaCl in both taxa. In both media, an increase of the 9-cis/all-trans beta-carotene ratio was observed in D. bardawil when the salt concentration increased, with a maximum value of 2.6 (in ART medium at 3M NaCl). In D. salina this ratio did not exhibit the same pattern, and the salt concentrations for maximal ratios were different in both media. The highest ratio obtained for this strain was 4.3 (in ART medium at 2M NaCl).

Carotenoids↗
PubMed2005

The effect of temperature and irradiance on the growth and carotenogenic capacity of seven strains of Dunaliella salina (Chlorophyta) cultivated under laboratory conditions.

The carotenogenic microalga Dunaliella salina is cultivated as a natural source of beta-carotene. The 9-cis isomer of beta-carotene is found only in natural sources having commercial advantages over the all-trans isomer due to its high liposolubility and antioxidant power. High irradiance appears to stimulate specifically all-trans beta-carotene accumulation in D. salina, whereas low temperature apparently elicits a-carotene and 9-cis betacarotene production. We studied the effect of temperature and irradiance on the growth and the carotenogenesis of three Chilean (CONC-001, CONC-006 and CONC-007) and four non-Chilean (from Mexico, China, Australia and Israel) strains of D. salina cultivated under two photon flux densities (40 and 110 micromol photons x m(-2) x s(-1)) and two temperatures (15 and 26 degrees C). The Chilean strain CONC-001 and all of the non-Chilean strains exhibited the highest growth rates and the maximum cell densities, whereas the Chilean strains CONC-006 and CONC-007 showed the lowest values in both parameters. The Australian strain showed the highest accumulation of total carotenoids per unit volume (40.7 mg x L(-1)), whereas the Chilean strains CONC-006 and CONC-007, the only ones isolated from Andean environments, yielded the highest amounts of carotenoids per cell (61.1 and 92.4 pg x cell(-1), respectively). Temperature was found to be more effective than irradiance in changing the qualitative and quantitative carotenoids composition. The Chilean strains accumulated 3.5-fold more alpha-carotene than the non-Chilean strains when exposed to 15 degrees C and, unlike the non-Chilean strains, also accumulated this pigment at 26 degrees C. The 9-cis/all-trans beta-carotene ratio was > 1.0 in all treatments for all strains, and the values were not greatly influenced by either temperature or photon flux density. Physiological and biotechnological implications of these results are discussed.

Analysis of Variance↗
PubMed1988

Mychonastes desiccatus Brown sp. nova (Chlorococcales, Chlorophyta)--an intertidal alga forming achlorophyllous desiccation-resistant cysts.

An intertidal Chlorella-like alga Mychonastes desiccatus Brown sp. nova, capable of forming achlorophyllous desiccation-resistant cysts, has been grown in unialgal culture. This small alga was first isolated from a dried sample of a well-studied microbial mat. The mat, located at North Pond, Laguna Figueroa, San Quintin, Baja California, Mexico, is a vertically-stratified microbial community which forms laminated sediments. Morphology, pigment composition and G+C content are within the range typical for the genus Chlorella s. 1. Unlike other chlorellae, however, upon desiccation M. desiccatus forms an achlorophyllous, lipid-filled cyst (thick-walled resting stage) in which no plastid is evident. Rewetting leads to chloroplast differentiation, excystment and recovery of the fully green alga. During desiccation, sporopollenin is deposited within a thickening cell wall. Encystment cannot be induced by growth in the dark. The formation of desiccation-induced cysts allows the alga to survive frequent and intermittent periods of dryness. These chlorellae tolerate wide ranges of acidity and temperature; they both grow and form cysts in media in which sodium ions are replaced with potassium. Although the cysts tolerate crystalline salts, the cell grow optimally in concentrations corresponding from three-quarters to full-strength seawater.

Biopolymers↗
PubMed2001

Comparative studies on utilizing nitrogen capacity between two macroalgae Gracilaria tenuistipitata var. liui (rhodophyta) and Ulva pertusa (chlorophyta). I. Nitrogen storage under nitrogen enrichment and starvation.

This paper deals with the N storage of Gracilaria tenuistipitata var. liui and Ulva pertusa under ammonium enrichment and starvation. After 10 days of ammonium enrichment, ammonium NH4+, free amino acid (FAA), protein (pro), chlorophyll (Chl), phycoerythrin (PE) and total dissolved nitrogen (TDN) of the two macroalgae increased significantly. Total nitrogen (TN) increased significantly from 3.65% to 5.78% dry weight of G. tenuistipitata var. liui and 2.82% to 5.07% dw of U. pertusa, respectively. Protein and FAA were the most important N storage pools in the macroalgae. During N-starvation period, individual N pools of the two species were depleted at exponential rates. Each N pool in U. pertusa decreased more rapidly than in G. tenuistipitata, var. liui and the latter was able to sustain fast growth for more time (> 20 days) than U. pertusa. N demands for supporting growth were different between the two species, U. pertusa grew more rapidly and had higher N demands than G. tenuistipitata var. liui did.

Amino Acids↗
PubMed2001

Comparative studies on utilizing nitrogen capacity between two macroalgae Gracilaria tenuistipitata var. liui (rhodophyta) and Ulva pertusa (chlorophyta). II. Feedback controls of intracellular nitrogen pools on nitrogen uptake.

The potential feedback by intracellular nitrogen pools on maximum N uptake (NH4+) rate were determined for Gracilaria tenuistipitata var. liui and Ulva pertusa. The results of correlation matrix analyzing showed that the surge uptake of ammonium seemed related to rapid changes in small intracellular pools of inorganic nitrogen or small peptide and amino acids rather than to changes in TN content of the macroalgae. The assimilation rates of nitrogen of U. pertusa and G. tenuistipitata increased slowly during N starvation and were mainly regulated by amino acids and some incorporation of amino acids into macromolecules. From ecological point of view, the fast-growing and uptaking nutrient U. pertusa is more suitable to improve water quality in integrated shrimp culture ponds in which external nutrient supplies are usually high and constant during the culture period, while G. tenuistipitata var. liui is more suitable to be polycultured in a waters with intermittence supply of nutrients.

Amino Acids↗
PubMed1991

Plastid genomes of the Rhodophyta and Chromophyta constitute a distinct lineage which differs from that of the Chlorophyta and have a composite phylogenetic origin, perhaps like that of the Euglenophyta.

A phylogenetic tree has been constructed from comparisons of entire 16S rRNA gene sequences from different prokaryotes and from several algal plastids. According to this study, and to previous work on the ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) large and small subunit genes, we postulate that: (1) rhodophyte and chromophyte plastid genomes have a common, composite phylogenetic origin which implies at least two different ancestors, a cyanobacterial and a beta-proteobacterial ancestor; (2) chlorophyte (green algae and land plants) plastids have a cyanobacterial ancestor which probably differs from that of rhodophyte and chromophyte plastids, and in any case constitute a different lineage; (3) euglenophyte plastid genomes also seem to have a composite phylogenetic origin which involves two different lineages.

Base Sequence↗
PubMed2006

Karyotypic differences and evolutionary tendencies of some species from the subgenus Obliquodesmus Mlad. of genus Scenedesmus Meyen (Chlorophyta, Chlorococcales).

Karyotype structures of Scenedesmus acuminatus (Lagerch.) Chod. and Scenedesmus pectinatus Meyen are compared. The karyotype of S. acuminatus (n = 5) is described for the first time. It reveals four large metacentric and one large submetacentric chromosomes (4M + 1SM). The established karyotype differences have been helpful in clarifying the taxonomic position of these two species. The cytological analyses of other related clonal cultures suggest an evolutionary transition from S. pectinatus towards S. regularis through S. pectinatus f. regularis, which correlates with the morphological data about their variability. These results are discussed from the cytogenetic, morphological and evolutionary point of view. On the basis of the karyotypic analysis, it was confirmed that from a taxonomic point of view S. pectinatus, S. acuminatus and S. regularis are separate biological species.

Biological Evolution↗
PubMed1999

Requisite Morphologic Interaction for Attachment between Ulva pertusa (Chlorophyta) and Symbiotic Bacteria.

: In order to understand the morphogenesis-inducing mechanism of Ulva pertusa by symbiotic bacteria, we observed the requisite conditions of bacteria for attachment to U. pertusa for algal morphogenesis. Non-morphogenesis-inducing bacterial mutants derived by ultraviolet irradiation did not attach onto the surface of this alga. Scanning electron microscopic observation during the process of morphogenesis in U. pertusa revealed a network-like structure formed on the algal surface within 1 week after application of bacteria. The bacteria attached onto the alga after 2 weeks of incubation. After this attachment process the morphologic change was observed in U. pertusa.

Journal Article↗
PubMed2000

The pH tolerance of Chlamydomonas applanata (Volvocales, Chlorophyta).

The effects of hydrogen ions on the growth and ultrastructure of Chlamydomonas applanata Pringsheim were examined. This species exhibits wide tolerance growing at pH values ranging from 3.4 to 8.4, with optimum growth obtained at 7.4. Growth is noticeably depressed at pH 4.4 and 3.4. At the ultrastructural level, exposure to pH 4.4 results in a 10% decrease in cell volume of single vegetative cells, an increase in pyrenoidal volume, and reduction of starch reserves. Palmelloid colonies also appear. pH 3.4 induces excessive production of mucilage and leads to the preponderance of palmelloid colonies. Cell death of both colony and single cells is seen, as well as loss of motility and abnormal cell division. Surviving single cells are significantly larger than controls, with thicker cell walls, smaller chloroplasts, and larger vacuome. Such cells entering dormancy ensure the survival of the species in times of stress.

Animals↗
PubMed2003

Accumulation of astaxanthin and lutein in Chlorella zofingiensis (Chlorophyta).

When grown photoautotrophically, Chlorella zofingiensis strain CCAP 211/14 accumulates a significant amount of valuable carotenoids, namely astaxanthin and lutein, of increasing demand for use as feed additives in fish and poultry farming, as colorants in food, and in health care products. Under standard batch-culture conditions, this microalgal strain exhibits high values of both growth rate (about 0.04 h(-1)) and standing cell population (over 10(11) cells l(-1), or 7 g dry weight l(-1)). Lutein, in a free (unesterified) form, was the prevalent carotenoid during early stages of cultivation (over 0.3 pg cell(-1), equal to 4 mg g(-1) dry weight, or 20 mg l(-1) culture), whereas esterified astaxanthin accumulated progressively, to reach a maximum (over 0.1 pg cell(-1), equal to 1.5 mg g(-1) dry weight, or 15 mg l(-1) culture) in the late stationary phase. A differential response of lutein and astaxanthin accumulation was also recorded with regard to the action of some environmental and nutritional factors. C. zofingiensis CCAP 211/14 represents a unique model system for analyzing the differential regulation of the levels of primary (lutein) and secondary (astaxanthin) carotenoids. Relevant also from the biotechnological viewpoint, this photosynthetic organism, with outstanding attributes for fast photosynthetic growth and carotenoid accumulation, might prove most valuable for its application to the mass production of either or both lutein and astaxanthin.

Chlorella↗