| amplification of dna polymerase gene fragments from viruses infecting microalgae. | nested pcr with three highly degenerate primers was used for amplification and identification of dna polymerase (pol) genes from viruses which infect three genera of microalgae. group-specific primers (avs1 and avs2) were designed on the basis of inferred amino acid sequences unique to the dna pol genes of viruses (pbcv-1 and ny-2a) that infect an endosymbiotic chlorella-like alga (chlorophyceae) and a virus (mpv-sp1) which infects the photosynthetic flagellate micromonas pusilla (prasinophyceae ... | 1995 | 7747950 |
| evolutionary relationships among large double-stranded dna viruses that infect microalgae and other organisms as inferred from dna polymerase genes. | in order to examine genetic relatedness among viruses that infect microalgae, dna polymerase gene (dna pol) fragments were amplified and sequenced from 13 virus clones that infect three genera of distantly related microalgae (chlorella strains nc64a and pbi, micromonas pusilla and chrysochromulina spp.). phylogenetic trees based on dna pol sequences and hybridization of total genomic dna showed similar branching patterns. genetic relatedness calculated from the hybridization and sequence data sh ... | 1996 | 8623526 |
| genetic diversity in marine algal virus communities as revealed by sequence analysis of dna polymerase genes. | algal-virus-specific pcr primers were used to amplify dna polymerase gene (pol) fragments (683 to 689 bp) from the virus-sized fraction (0.02 to 0.2 microns) concentrated from inshore and offshore water samples collected from the gulf of mexico. algal-virus-like dna pol genes were detected in five samples collected from the surface and deep chlorophyll maximum. pcr products from an offshore station were cloned, and the genetic diversity of 33 fragments was examined by restriction fragment length ... | 1996 | 8702280 |
| identification of | [8-vinyl]-protochlorophyllide a1 was isolated from a prochloron sp. associated with the host ascidian, lissoclinum patella. to obtain sufficient amounts for identification of the purified pigment, suitable extraction procedures and hplc systems were developed. the structure was finally elucidated by uv-vis and fluorescence spectroscopy, mass spectrometry and nmr (rotating-frame overhauser enhancement spectroscopy). [8-vinyl]-protochlorophyllide a was originally detected only as an intermediate i ... | 1999 | 10082792 |
| protistan grazing analysis by flow cytometry using prey labeled by in vivo expression of fluorescent proteins. | selective grazing by protists can profoundly influence bacterial community structure, and yet direct, quantitative observation of grazing selectivity has been difficult to achieve. in this investigation, flow cytometry was used to study grazing by the marine heterotrophic flagellate paraphysomonas imperforata on live bacterial cells genetically modified to express the fluorescent protein markers green fluorescent protein (gfp) and red fluorescent protein (rfp). broad-host-range plasmids were con ... | 2003 | 14602649 |
| discovery of a dsrna virus infecting the marine photosynthetic protist micromonas pusilla. | we report the isolation of the first double-stranded (ds) rna virus in the family reoviridae that infects a protist (microalga micromonas pusilla, prasinophyceae). the dsrna genome was composed of 11 segments ranging between 0.8 and 5.8 kb, with a total size of approximately 25.5 kb. the virus (mprnav-01b) could not be assigned to the genus level because host type, genome size, and number of segments smaller than 2 kb did not correspond to either of the two existing 11-segmented dsrna genera rot ... | 2004 | 14980488 |
| development of multispecies algal bioassays using flow cytometry. | multispecies algal bioassays, suitable for assessing copper toxicity, were developed with three marine (micromonas pusilla, phaeodactylum tricornutum, and heterocapsa niei) and three freshwater (microcystis aeruginosa, pseudokirchneriella subcapitata, and trachelomonas sp.) microalgae. flow cytometry was used to separate and count algal signals based on pigment fluorescence and cell size. species were mixed together on the basis of equivalent surface areas to avoid the confounding effect on toxi ... | 2004 | 15376531 |
| short-term physiologic effects of mechanical flow sorting and the becton-dickinson cell concentrator in cultures of the marine phytoflagellata emiliania huxleyi and micromonas pusilla. | in contrast to large, high-efficiency cytometers, mechanically sorting benchtop instruments provide a feasible alternative for shipboard cell sorting of oceanic microbial communities. however, sorting efficiency of these instruments is constrained by their maximum sorting rate of approximately 300 cells/s and by constant dilution of sorted samples by sheath flow. these factors often render too low sorted cell concentrations for postsorting experiments of oceanic phytoplankton populations of low ... | 2005 | 15791646 |
| use of ultrafiltration to isolate viruses from seawater which are pathogens of marine phytoplankton. | viruses may be major structuring elements of phytoplankton communities and hence important regulators of nutrient and energy fluxes in aquatic environments. in order to ascertain whether viruses are potentially important in dictating phytoplankton community structure, it is essential to determine the extent to which representative phytoplankton taxa are susceptible to viral infection. we used a spiral ultrafiltration cartridge (30,000-molecular-weight cutoff) to concentrate viruses from seawater ... | 1991 | 16348439 |
| genetic diversity of algal viruses which lyse the photosynthetic picoflagellate micromonas pusilla (prasinophyceae). | the genetic similarity among eight clones of micromonas pusilla virus (mpv) isolated from five geographic locations was measured by dna hybridization. our objective was to explore the existence of genetically distinct populations of mpv by comparing the similarity among mpvs isolated from a single water sample to the similarity among viruses isolated from geographically distant locations. the highest and lowest similarities we observed were 70% (plusmn) 1.1% (mean (plusmn) standard error [se], n ... | 1995 | 16535105 |
| micromonas pusilla reovirus: a new member of the family reoviridae assigned to a novel proposed genus (mimoreovirus). | micromonas pusilla reovirus (mprv) is an 11-segmented, double-stranded rna virus isolated from the marine protist micromonas pusilla. sequence analysis (including conserved termini and presence of core motifs of reovirus polymerase), morphology and physicochemical properties confirmed the status of mprv as a member of the family reoviridae. electron microscopy showed that intact virus particles are unusually larger (90-95 nm) than the known size of particles of viruses belonging to the family re ... | 2006 | 16603541 |
| resource dynamics during infection of micromonas pusilla by virus mpv-sp1. | viruses infecting marine phytoplankton drive phytoplankton diversity, terminate blooms and shuttle genetic material. assessments of the scale of viral impacts on trophic networks are, however, speculative. we investigated fluxes of dna between host and virus during infection of the prasinophyte alga micromonas pusilla by phycodnavirus mpv sp1. under a light-dark regimen, viral genomes accumulated to a transient peak within 24 h, at the expense of both host dna synthesis and nuclear dna. viral ge ... | 2007 | 17922756 |
| the diversity of small eukaryotic phytoplankton (< or =3 microm) in marine ecosystems. | small cells dominate photosynthetic biomass and primary production in many marine ecosystems. traditionally, picoplankton refers to cells < or =2 microm. here we extend the size range of the organisms considered to 3 microm, a threshold often used operationally in field studies. while the prokaryotic component of picophytoplankton is dominated by two genera, prochlorococcus and synechococcus, the eukaryotic fraction is much more diverse. since the discovery of the ubiquitous micromonas pusilla i ... | 2008 | 18564290 |
| effects of ultraviolet radiation on marine virus-phytoplankton interactions. | abstract ambient ultraviolet radiation (uvr) is harmful to many biological systems and increased uvr, due to a reduced ozone layer, may have many unforeseen consequences. viruses are the most abundant biological particles in the sea and are thought to play an important role in the structure and functioning of aquatic ecosystems. although an increasing number of studies have been published during the last 15 years, aquatic viral ecology is still in its infancy and little is known about the effect ... | 2003 | 19719609 |
| metabolic engineering of omega-3 long-chain polyunsaturated fatty acids in plants using an acyl-coa delta6-desaturase with omega3-preference from the marine microalga micromonas pusilla. | long-chain (> or = c20) polyunsaturated fatty acids (lc-pufa) epa and dha (20:5(delta5,8,11,14,17) and 22:6(delta4,7,10,13,16,19)) have well-documented health benefits against coronary heart disease, rheumatoid arthritis and other disorders. currently, the predominant sources of these fatty acids are marine fish and algal oils, but research is being conducted to ensure that a sustainable, land-based production system can be developed. we here describe the metabolic engineering of an artificial p ... | 2010 | 20004733 |
| metaproteomic and metagenomic analyses of defined oceanic microbial populations using microwave cell fixation and flow cytometric sorting. | a major obstacle in the molecular investigation of natural, especially oceanic, microbial cells is their adequate preservation for further land-based molecular analyses. here, we examined the use of microwaves for cell fixation before high-speed flow cytometric sorting to define the metaproteomes and metagenomes of key microbial populations. the microwave fixation procedure was established using cultures of synechococcus cyanobacteria, the photosynthetic eukaryote micromonas pusilla and the gamm ... | 2010 | 20618860 |
| net production/consumption of fluorescent coloured dissolved organic matter by natural bacterial assemblages growing on marine phytoplankton exudates. | understanding the distribution of coloured dissolved organic matter (cdom) in the oceans and its role in the global carbon cycle requires a better knowledge of the coloured materials produced and consumed by marine phytoplankton and bacteria. in this work we examined the net uptake/release of cdom by a natural bacterial community growing on dom derived from four phytoplankton species cultured in axenic conditions. fluorescent humic-like substances exuded by phytoplankton (ex/em: 310 nm/392 nm; p ... | 2011 | 21742918 |
| The dinoflagellate Dinophysis mitra collects multiple plastids through kleptoplastidy. | Kleptoplastidy is the retention of plastids obtained from ingested algal prey, which may remain temporarily functional and be used for photosynthesis by the predator. We showed that the marine dinoflagellate Dinophysis mitra has great kleptoplastid diversity. We obtained 308 plastid rbcL sequences by gene cloning from 14 D. mitra cells and 102 operational taxonomic units (OTUs). Most sequences were new in the genetic database and positioned within Haptophyceae (227 sequences [73.7%], 80 OTUs [78 ... | 2011 | 22101051 |
| early gene duplication within chloroplastida and its correspondence with relocation of starch metabolism to chloroplasts. | the endosymbiosis event resulting in the plastid of photosynthetic eukaryotes was accompanied by the appearance of a novel form of storage polysaccharide in rhodophyceae, glaucophyta, and chloroplastida. previous analyses indicated that starch synthesis resulted from the merging of the cyanobacterial and the eukaryotic storage polysaccharide metabolism pathways. we performed a comparative bioinformatic analysis of six algal genome sequences to investigate this merger. specifically, we analyzed t ... | 2008 | 18245855 |
| application of a delta-6 desaturase with α-linolenic acid preference on eicosapentaenoic acid production in mortierella alpina. | delta-6 desaturase (fads6) is a key bifunctional enzyme desaturating linoleic acid (la) or α-linolenic acid (ala) in the biosynthesis of polyunsaturated fatty acids (pufas). in previous work, we analyzed the substrate specificity of two fads6 enzymes from mortierella alpina atcc 32222 (mafads6) and micromonas pusilla ccmp1545 (mpfads6), which showed preference for la and ala, respectively. we also clarified the pufa profiles in m. alpina, where these lipids were synthesized mainly via the ω6 pat ... | 2016 | 27364006 |
| a comparative study of iron uptake mechanisms in marine microalgae: iron binding at the cell surface is a critical step. | we investigated iron uptake mechanisms in five marine microalgae from different ecologically important phyla: the diatoms phaeodactylum tricornutum and thalassiosira pseudonana, the prasinophyceae ostreococcus tauri and micromonas pusilla, and the coccolithophore emiliania huxleyi. among these species, only the two diatoms were clearly able to reduce iron, via an inducible (p. tricornutum) or constitutive (t. pseudonana) ferrireductase system displaying characteristics similar to the yeast (sacc ... | 2012 | 23033141 |
| prasinoviruses of the marine green alga ostreococcus tauri are mainly species specific. | prasinoviruses infecting unicellular green algae in the order mamiellales (class mamiellophyceae) are commonly found in coastal marine waters where their host species frequently abound. we tested 40 ostreococcus tauri viruses on 13 independently isolated wild-type o. tauri strains, 4 wild-type o. lucimarinus strains, 1 ostreococcus sp. ("ostreococcus mediterraneus") clade d strain, and 1 representative species of each of two other related species of mamiellales, bathycoccus prasinos and micromon ... | 2012 | 22318150 |