| multiple evolutionary origins of prochlorophytes, the chlorophyll b-containing prokaryotes. | prochlorophytes are prokaryotes that carry out oxygenic photosynthesis using chlorophylls a and b, but lack phycobiliproteins as light-harvesting pigments. these characteristics distinguish them from cyanobacteria, which contain phycobiliproteins, but no chlorophyll b. three prochlorophyte genera have been described: prochloron, prochlorothrix and prochlorococcus. the prochlorophytes share their pigment characteristics with green plant and euglenoid chloroplasts, which has led to a debate on whe ... | 1992 | 1731224 |
| multiple evolutionary origins of prochlorophytes within the cyanobacterial radiation. | the taxonomic group prochlorales (lewin 1977) burger-wiersma, stal and mur 1989 was established to accommodate a set of prokaryotic oxygenic phototrophs which, like plant, green algal and euglenoid chloroplasts, contain chlorophyll b instead of phycobiliproteins. prochlorophytes were originally proposed (with concomitant scepticism) to be a monophyletic group sharing a common ancestry with these 'green' chloroplasts. results from molecular sequence phylogenies, however, have suggested that proch ... | 1992 | 1731225 |
| partial sequence of ribulose-1,5-bisphosphate carboxylase/oxygenase and the phylogeny of prochloron and prochlorococcus (prochlorales). | the prochlorophytes, oxygenic photosynthetic prokaryotes having no phycobiliprotein but possessing chlorophylls a and b, have been proposed to have a common ancestry with green chloroplasts, yet this is still controversal. we report here that partial sequence comparisons of the large subunit of ribulose-1,5'-bisphosphate carboxylase/oxygenase, including sequence data from two prochlorophytes, prochlorococcus and prochloron, indicate that prochlorococcus is more closely related to a photosyntheti ... | 1995 | 7643418 |
| characterization of the single psba gene of prochlorococcus marinus ccmp 1375 (prochlorophyta). | dna sequence, copy number, expression and phylogenetic relevance of the psba gene from the abundant marine prokaryote p. marinus ccmp 1375 was analyzed. the 7 amino acids near the c-terminus missing in higher plant and in prochlorothrix hollandica d1 proteins are present in the derived amino acid sequence. p. marinus contains only a single psba gene. thus, this organism lacks the ability to adapt its photosystem ii by replacement of one type of d1 by another, as several cyanobacteria do. phyloge ... | 1995 | 7766900 |
| cyanobacterial community structure as seen from rna polymerase gene sequence analysis. | pcr was used to amplify dna-dependent rna polymerase gene sequences specifically from the cyanobacterial population in a seawater sample from the sargasso sea. sequencing and analysis of the cloned fragments suggest that the population in the sample consisted of two distinct clusters of prochlorococcus-like cyanobacteria and four clusters of synechococcus-like cyanobacteria. the diversity within these clusters was significantly different, however. clones within each synechococcus-like cluster we ... | 1994 | 7944363 |
| sequencing of rapd fragments amplified from the genome of the prokaryote prochlorococcus marinus (prochlorophyta). | dna fingerprint patterns from the chlorophyll a and b containing prokaryote prochlorococcus marinus were generated with the rapd technique using two primers derived from repetitive sequence motifs, [(gata)4 and m13] and a random primer (opb-10]. five rapd fragments were reamplified, cloned and sequenced. the clones m13/1300 and opb-10/1100 contained open reading frames, whereas the (gata)4 fragments were interrupted by stop codons in all frames indicating their noncoding function and possessed a ... | 1995 | 8528133 |
| coexistence of phycoerythrin and a chlorophyll a/b antenna in a marine prokaryote. | prochlorococcus marinus ccmp 1375, a ubiquitous and ecologically important marine prochlorophyte, was bound to possess functional genes coding for the alpha and beta subunits of a phycobiliprotein. the latter is similar to phycoerythrins (pe) from marine synechococcus cyanobacteria and bind a phycourobilin-like pigment as the major chromophore. however, differences in the sequences of the alpha and beta chains compared with known pe subunits and the presence of a single bilin attachment site on ... | 1996 | 8855320 |
| an immunological approach to detect phosphate stress in populations and single cells of photosynthetic picoplankton. | in the marine cyanobacterium synechococcus sp. strain wh7803, psts is a 32-kda cell wall-associated phosphate-binding protein specifically synthesized under conditions of restricted inorganic phosphate (p1) availability (d. j. scanlan, n. h. mann, and n. g. carr, mol. microbiol. 10:181-191, 1993). we have assessed its use as a potential diagnostic marker for the p status of photosynthetic picoplankton. expression of psts in synechococcus sp. strain wh7803 was observed when the p1 concentration f ... | 1997 | 9172363 |
| localization of an open reading frame with homology to human aspartoacylase upstream from psba in the prokaryote prochlorococcus marinus ccmp 1375. | an open reading frame encoding a polypeptide with significant homology (about 28% identity and 16% similarity) to human aspartoacylase (aspa) was identified in the genome of prochlorococcus marinus ccmp 1375, an oxyphototrophic bacterium. sequence alignments show that, in particular, the regions previously suggested to form the catalytic core of human aspa are evolutionarily conserved and nearly identical to that found in the prochlorococcus putative aspa. a glutamate at position 273 is located ... | 1997 | 9255521 |
| diversity of the ribulose bisphosphate carboxylase/oxygenase form i gene (rbcl) in natural phytoplankton communities. | the phytoplankton of the world's oceans play an integral part in global carbon cycling and food webs by conversion of carbon dioxide into organic carbon. they accomplish this task through the action of the calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). here we have investigated the phylogenetic diversity in the form i rbcl locus in natural phytoplankton communities of the open ocean and representative clones of marine autotrophic picoplankton by mrna or dna amplif ... | 1997 | 9293012 |
| synechococcus diversity in the california current as seen by rna polymerase (rpoc1) gene sequences of isolated strains. | because they are ubiquitous in a range of aquatic environments and culture methods are relatively advanced, cyanobacteria may be useful models for understanding the extent of evolutionary adaptation of prokaryotes in general to environmental gradients. the roles of environmental variables such as light and nutrients in influencing cyanobacterial genetic diversity are still poorly characterized, however. in this study, a total of 15 synechococcus strains were isolated from the oligotrophic edge o ... | 1997 | 9361417 |
| rapid diversification of marine picophytoplankton with dissimilar light-harvesting structures inferred from sequences of prochlorococcus and synechococcus (cyanobacteria). | cultured isolates of the unicellular planktonic cyanobacteria prochlorococcus and marine synechococcus belong to a single marine picophytoplankton clade. within this clade, two deeply branching lineages of prochlorococcus, two lineages of marine a synechococcus and one lineage of marine b synechococcus exhibit closely spaced divergence points with low bootstrap support. this pattern is consistent with a near-simultaneous diversification of marine lineages with divinyl chlorophyll b and phycobili ... | 1998 | 9452521 |
| unique organization of the dnaa region from prochlorococcus marinus ccmp1375, a marine cyanobacterium. | in order to study dna replication control elements in cyanobacteria we cloned and sequenced the dnaa gene from the marine cyanobacterium prochlorococcus marinus. the dnaa gene is ubiquitous among bacteria and encodes the dna replication initiation factor dnaa. the deduced amino acid sequence of the p. marinus dnaa protein shows highest similarity to the dnaa protein from the freshwater cyanobacterium synechocystis sp. pcc6803. using a solid-phase dna binding assay we demonstrated that both cyano ... | 1998 | 9563839 |
| physiology and molecular phylogeny of coexisting prochlorococcus ecotypes. | the cyanobacterium prochlorococcus is the dominant oxygenic phototroph in the tropical and subtropical regions of the world's oceans. it can grow at a range of depths over which light intensities can vary by up to 4 orders of magnitude. this broad depth distribution has been hypothesized to stem from the coexistence of genetically different populations adapted for growth at high- and low-light intensities. here we report direct evidence supporting this hypothesis, which has been generated by iso ... | 1998 | 9624000 |
| rnase p rna from prochlorococcus marinus: contribution of substrate domains to recognition by a cyanobacterial ribozyme. | the molecular organisation of the prochlorococcus marinus rnpb gene and the catalytic activity of the encoded rna were characterised. kinetic parameters for several pre-trna substrates were comparable to those from other eubacterial rnase p rnas, although unusually high cation concentrations were required. the cca-end of pre-trnas is essential for efficient turnover despite the lack of the canonical binding motif in p. marinus rnase p rna. a trnr gene is located only 38 nt upstream the rnpb 5' e ... | 1998 | 9708890 |
| expression of the psba gene in the marine oxyphotobacteria prochlorococcus spp. | the oxygenic photosynthetic prokaryotes prochlorococcus marinus ss120 (ccmp1375) and prochlorococcus sp. med4 (ccmp 1378) were previously shown to exhibit different pigmentation and ecophysiological characteristics. the former strain has a much lower divinyl-chl a to b ratio and is adapted to lower photon flux densities than the latter. in contrast to the cyanobacteria examined so far, both strains possess only one copy of the psba gene, encoding the d1 protein of photosystem ii core. in acclima ... | 1998 | 9799555 |
| prochlorococcus, a marine photosynthetic prokaryote of global significance. | the minute photosynthetic prokaryote prochlorococcus, which was discovered about 10 years ago, has proven exceptional from several standpoints. its tiny size (0.5 to 0.7 microm in diameter) makes it the smallest known photosynthetic organism. its ubiquity within the 40 degrees s to 40 degrees n latitudinal band of oceans and its occurrence at high density from the surface down to depths of 200 m make it presumably the most abundant photosynthetic organism on earth. prochlorococcus typically divi ... | 1999 | 10066832 |
| light-harvesting antenna function of phycoerythrin in prochlorococcus marinus | prochlorococcus marinus strain ccmp 1375 is the sole prokaryote to possess phycoerythrin in addition to (divinyl-)chlorophyll a/b binding antenna complexes. here we demonstrate, employing a spectrofluorimetric assay, that phycoerythrin serves a light-harvesting antenna function (transfers energy to chlorophylls). | 1999 | 10076020 |
| 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 |
| niche-partitioning of prochlorococcus populations in a stratified water column in the eastern north atlantic ocean. | the in situ community structure of prochlorococcus populations in the eastern north atlantic ocean was examined by analysis of prochlorococcus 16s rdna sequences with three independent approaches: cloning and sequencing, hybridization to specific oligonucleotide probes, and denaturing gradient gel electrophoresis (dgge). the hybridization of high-light (hl) and low-light (ll) prochlorococcus genotype-specific probes to two depth profiles of pcr-amplified 16s rdna sequences revealed that in these ... | 1999 | 10347047 |
| chlorophyll b and phycobilins in the common ancestor of cyanobacteria and chloroplasts. | photosynthetic organisms have a variety of accessory pigments, on which their classification has been based. despite this variation, it is generally accepted that all chloroplasts are derived from a single cyanobacterial ancestor. how the pigment diversity has arisen is the key to revealing their evolutionary history. prochlorophytes are prokaryotes which perform oxygenic photosynthesis using chlorophyll b, like land plants and green algae (chlorophyta), and were proposed to be the ancestors of ... | 1999 | 10408441 |
| mechanisms of dominance: coexistence of picocyanobacterial genotypes in a freshwater ecosystem | the autotrophic picoplankton of the pelagic zone of the mesotrophic lake constance is dominated by phycoerythrin-rich unicellular cyanobacteria phylogenetically related to the marine synechococcus and prochlorococcus cluster. in lake constance, the abundance of picocyanobacteria shows a recurrent pattern of seasonal variations. evidence of diverse subpopulations was obtained by electron-microscopic examination of natural water samples and isolated strains that unveiled different surface structur ... | 1999 | 10415167 |
| phycoerythrins of the oxyphotobacterium prochlorococcus marinus are associated to the thylakoid membrane and are encoded by a single large gene cluster. | an intrinsic divinyl-chlorophyll a/b antenna and a particular form of phycobiliprotein, phycoerythrin (pe) iii, coexist in the marine oxyphotobacterium prochlorococcus marinus ccmp 1375. the genomic region including the cpeb/a operon of p. marinus was analysed. it encompasses 10,153 nucleotides that encode three structural phycobiliproteins and at least three (possibly five) different polypeptides analogous to cyanobacterial or red algal proteins involved either in the linkage of subunits or the ... | 1999 | 10437834 |
| a small and compact genome in the marine cyanobacterium prochlorococcus marinus ccmp 1375: lack of an intron in the gene for trna(leu)(uaa) and a single copy of the rrna operon. | data obtained by pulsed field gel electrophoresis revealed for prochlorococcus marinus ccmp 1375 a genome size of 1.81+/-0.04 mbp. this value is significantly smaller than for all other cyanobacteria investigated so far. the absence of an intron in the gene for trna(leu)(uaa), which otherwise is widespread among cyanobacteria, and the additional finding that the ribosomal operon exists as a single copy suggest that the deletion of non-essential sequences played a major role in the evolution of p ... | 1999 | 10585547 |
| in situ hybridization of prochlorococcus and synechococcus (marine cyanobacteria) spp. with rrna-targeted peptide nucleic acid probes. | a simple method for whole-cell hybridization using fluorescently labeled rrna-targeted peptide nucleic acid (pna) probes was developed for use in marine cyanobacterial picoplankton. in contrast to established protocols, this method is capable of detecting rrna in prochlorococcus, the most abundant unicellular marine cyanobacterium. because the method avoids the use of alcohol fixation, the chlorophyll content of prochlorococcus cells is preserved, facilitating the identification of these cells i ... | 2000 | 10618237 |
| multiplication of antenna genes as a major adaptation to low light in a marine prokaryote. | two ecotypes of the prokaryote prochlorococcus adapted to distinct light niches in the ocean have been described recently. these ecotypes are characterized by their different (divinyl-) chlorophyll (chl) a to chl b ratios and 16s rrna gene signatures, as well as by their significantly distinct irradiance optima for growth and photosynthesis [moore, l. r., rocap, g. & chisholm, s. w. (1998) nature (london) 393, 464-467]. however, the molecular basis of their physiological differences remained, so ... | 2000 | 10725393 |
| prochlorococcus marinus chisholm et al. 1992 subsp. pastoris subsp. nov. strain pcc 9511, the first axenic chlorophyll a2/b2-containing cyanobacterium (oxyphotobacteria). | the formal description of prochlorococcus marinus chisholm et al. 1992, 299 was based on the non-axenic nomenclatural type, strain ccmp 1375t. the purification and properties of the axenic strain pcc 9511, derived from the same primary culture (sarg) as the type species, are reported here. prochlorococcus pcc 9511 differs from the latter in possessing horseshoe-shaped thylakoids, exhibiting a low chlorophyll b2 content and lacking phycoerythrin, but shares these phenotypic properties with prochl ... | 2000 | 11034495 |
| quantitative analysis of small-subunit rrna genes in mixed microbial populations via 5'-nuclease assays. | few techniques are currently available for quantifying specific prokaryotic taxa in environmental samples. quantification of specific genotypes has relied mainly on oligonucleotide hybridization to extracted rrna or intact rrna in whole cells. however, low abundance and cellular rrna content limit the application of these techniques in aquatic environments. in this study, we applied a newly developed quantitative pcr assay (5'-nuclease assay, also known as taqman) to quantify specific small-subu ... | 2000 | 11055900 |
| prochlorococcus marinus strain pcc 9511, a picoplanktonic cyanobacterium, synthesizes the smallest urease. | the urease from the picoplanktonic oceanic prochlorococcus marinus sp. strain pcc 9511 was purified 900-fold to a specific activity of 94.6 micromol urea min(-1) (mg protein)(-1) by heat treatment and liquid chromatography methods. the enzyme, with a molecular mass of 168 kda as determined by gel filtration, is the smallest urease known to date. three different subunits with apparent molecular masses of 11 kda (gamma or urea; predicted molecular mass 11 kda), 13 kda (ss or ureb; predicted molecu ... | 2000 | 11101668 |
| nitrogen deprivation strongly affects photosystem ii but not phycoerythrin level in the divinyl-chlorophyll b-containing cyanobacterium prochlorococcus marinus. | effects of nitrogen limitation on photosystem ii (psii) activities and on phycoerythrin were studied in batch cultures of the marine oxyphotobacterium prochlorococcus marinus. dramatic decreases in photochemical quantum yields (f(v)/f(m)), the amplitude of thermoluminescence (tl) b-band, and the rate of q(a) reoxidation were observed within 12 h of growth in nitrogen-limited conditions. the decline in f(v)/f(m) paralleled changes in the tl b-band amplitude, indicative of losses in psii activitie ... | 2001 | 11115645 |
| cell cycle regulation by light in prochlorococcus strains. | the effect of light on the synchronization of cell cycling was investigated in several strains of the oceanic photosynthetic prokaryote prochlorococcus using flow cytometry. when exposed to a light-dark (l-d) cycle with an irradiance of 25 micromol of quanta x m(-2) x s(-1), the low-light-adapted strain ss 120 appeared to be better synchronized than the high-light-adapted strain pcc 9511. submitting l-d-entrained populations to shifts (advances or delays) in the timing of the "light on" signal t ... | 2001 | 11157244 |
| chromatic adaptation in marine synechococcus strains. | characterization of two genetically distinct groups of marine synechococcus sp. strains shows that one, but not the other, increases its phycourobilin/phycoerythrobilin chromophore ratio when growing in blue light. this ability of at least some marine synechococcus strains to chromatically adapt may help explain their greater abundance in particular ocean environments than cyanobacteria of the genus prochlorococcus. | 2001 | 11157276 |
| diel expression of cell cycle-related genes in synchronized cultures of prochlorococcus sp. strain pcc 9511. | the cell cycle of the chlorophyll b-possessing marine cyanobacterium prochlorococcus is highly synchronized under natural conditions. to understand the underlying molecular mechanisms we cloned and sequenced dnaa and ftsz, two key cell cycle-associated genes, and studied their expression. an axenic culture of prochlorococcus sp. strain pcc 9511 was grown in a turbidostat with a 12 h-12 h light-dark cycle for 2 weeks. during the light periods, a dynamic light regimen was used in order to simulate ... | 2001 | 11208789 |
| diversity and community structure within anoxic sediment from marine salinity meromictic lakes and a coastal meromictic marine basin, vestfold hilds, eastern antarctica. | 16s rdna clone library analysis was used to examine the biodiversity and community structure within anoxic sediments of several marine-type salinity meromictic lakes and a coastal marine basin located in the vestfolds hills area of eastern antarctica. from 69 to 130 (555 total) 16s rdna clones were analysed from each sediment sample, and restriction fragment length polymorphism (rflp) and sequence analysis grouped the clones into 202 distinct phylotypes (a clone group with sequence similarity of ... | 2000 | 11220308 |
| in vivo regulation of glutamine synthetase activity in the marine chlorophyll b-containing cyanobacterium prochlorococcus sp. strain pcc 9511 (oxyphotobacteria). | the physiological regulation of glutamine synthetase (gs; ec 6.3.1.2) in the axenic prochlorococcus sp. strain pcc 9511 was studied. gs activity and antigen concentration were measured using the transferase and biosynthetic assays and the electroimmunoassay, respectively. gs activity decreased when cells were subjected to nitrogen starvation or cultured with oxidized nitrogen sources, which proved to be nonusable for prochlorococcus growth. the gs activity in cultures subjected to long-term phos ... | 2001 | 11319101 |
| differential expression of antenna and core genes in prochlorococcus pcc 9511 (oxyphotobacteria) grown under a modulated light-dark cycle. | the continuous changes in incident solar light occurring during the day oblige oxyphototrophs, such as the marine prokaryote prochlorococcus, to modulate the synthesis and degradation rates of their photosynthetic components finely. how this natural phenomenon influences the diel expression of photosynthetic genes has never been studied in this ecologically important oxyphotobacterium. here, the high light-adapted strain prochlorococcus sp. pcc 9511 was grown in large-volume continuous culture u ... | 2001 | 11321533 |
| closely related prochlorococcus genotypes show remarkably different depth distributions in two oceanic regions as revealed by in situ hybridization using 16s rrna-targeted oligonucleotides. | an in situ hybridization method was applied to the identification of marine cyanobacteria assignable to the genus prochlorococcus using horseradish-peroxidase-labelled 16s rrna-targeted oligonucleotide probes in combination with tyramide signal amplification (tsa). with this method very bright signals were obtained, in contrast to hybridizations with oligonucleotides monolabelled with fluorochromes, which failed to give positive signals. genotype-specific oligonucleotides for high light (hl)- an ... | 2001 | 11429451 |
| phytoplankton group dynamics in the bay of marseilles during a 2-year survey based on analytical flow cytometry. | the bay of marseilles is under the influence of a large urban concentration and its maritime activities. all of them discharge compounds (hydrocarbons, excess nutrients, heavy metals, chemicals, etc.) that can alter the marine ecosystem. to investigate whether ultraphytoplankton (<10 microm) could be used as biosensors for their own ecosystem, a 2-year survey was conducted in the bay of marseilles. | 2001 | 11429775 |
| expression and phylogeny of the multiple antenna genes of the low-light-adapted strain prochlorococcus marinus ss120 (oxyphotobacteria). | in contrast to typical cyanobacteria, prochlorococcus strains possess an intrinsic divinyl-chlorophyll (chl) a/b-protein complex instead of phycobilisomes as the major light-harvesting system. these pigment-protein complexes are encoded by a variable number of pcb genes depending on the ecotype to which the prochlorococcus strain belongs: low-light-adapted strains possess several pcb gene copies whereas only a single copy is present in high-light-adapted strains. in this study, the light-regulat ... | 2001 | 11575723 |
| oxyphotobacteria. antenna ring around photosystem i. | the oceanic picoplankton prochlorococcus - probably the most abundant photosynthetic organism on our planet - can grow at great depths where light intensity is very low. we have found that the chlorophyll-binding proteins in a deep-living strain of this oxyphotobacterium form a ring around a trimer of the photosystem i (ps i) photosynthetic reaction centre, a clever arrangement that maximizes the capture of light energy in such dim conditions. | 2001 | 11595938 |
| phycobiliprotein genes of the marine photosynthetic prokaryote prochlorococcus: evidence for rapid evolution of genetic heterogeneity. | prochlorococcus is a major photosynthetic prokaryote in nutrient-limited, open ocean environments and an important participant in the global carbon cycle. this phototroph is distinct from other members of the cyanobacterial lineage to which it belongs because it utilizes a chlorophyll a2/b(2) light-harvesting complex as its major antenna, instead of phycobilisomes. recently, genes encoding the phycobiliprotein phycoerythrin were identified in several prochlorococcus isolates, thus making it the ... | 2001 | 11700369 |
| regulation of glutamine synthetase by metal-catalyzed oxidative modification in the marine oxyphotobacterium prochlorococcus. | the inactivation of glutamine synthetase (gs; ec 6.3.1.2) by metal-catalyzed oxidation (mco) systems was studied in several prochlorococcus strains, including the axenic pcc 9511. gs was inactivated in the presence of various oxidative systems, either enzymatic (as nad(p)h+nad(p)h-oxidase+fe(3+)+o(2)) or non-enzymatic (as ascorbate+fe(3+)+o(2)). this process required the presence of oxygen and a metal cation, and is prevented under anaerobic conditions. catalase and peroxidase, but not superoxid ... | 2001 | 11786230 |
| genotyping of axenic and non-axenic isolates of the genus prochlorococcus and the omf-'synechococcus' clade by size, sequence analysis or rflp of the internal transcribed spacer of the ribosomal operon. | pcr amplicons of the internal transcribed spacer (its) of the rrn operon of three axenic omf (oceanic, marine and freshwater) strains of 'synechococcus' (wh7803, pcc 7001 and pcc 6307, respectively) differ greatly in length from that of the axenic prochlorococcus marinus subsp. pastoris pcc 9511(t), although these four cyanobacteria cluster relatively closely in phylogenetic trees inferred from 16s rrna gene sequences. the itss of three strains (pcc 9511(t), pcc 6307 and pcc 7001) were sequenced ... | 2002 | 11832509 |
| cyanobacterial photosynthesis in the oceans: the origins and significance of divergent light-harvesting strategies. | prochlorococcus and synechococcus are abundant unicellular cyanobacteria and major participants in global carbon cycles. although they are closely related and often coexist in the same ocean habitat, they possess very different photosynthetic light-harvesting antennas. whereas synechococcus and the majority of cyanobacteria use phycobilisomes, prochlorococcus has evolved to use a chlorophyll a(2)/b(2) light-harvesting complex. here, we present a scenario to explain how the prochlorococcus antenn ... | 2002 | 11864823 |
| resolution of prochlorococcus and synechococcus ecotypes by using 16s-23s ribosomal dna internal transcribed spacer sequences. | cultured isolates of the marine cyanobacteria prochlorococcus and synechococcus vary widely in their pigment compositions and growth responses to light and nutrients, yet show greater than 96% identity in their 16s ribosomal dna (rdna) sequences. in order to better define the genetic variation that accompanies their physiological diversity, sequences for the 16s-23s rdna internal transcribed spacer (its) region were determined in 32 prochlorococcus isolates and 25 synechococcus isolates from aro ... | 2002 | 11872466 |
| genetic tools for cyanobacteria. | cyanobacteria are oxygenic photosynthetic bacteria that have been used increasingly to study diverse biological processes, including photosynthesis and its regulation; cell differentiation and n2 fixation; metabolism of nitrogen, carbon, and hydrogen; resistance to environmental stresses; and molecular evolution. many vectors and other genetic tools have been developed for unicellular and filamentous strains of cyanobacteria. transformation, electroporation, and conjugation are used for gene tra ... | 2002 | 11876404 |
| genes essential to sodium-dependent bicarbonate transport in cyanobacteria: function and phylogenetic analysis. | the cyanobacterium synechocystis sp. strain pcc 6803 possesses two co(2) uptake systems and two hco(3)(-) transporters. we transformed a mutant impaired in co(2) uptake and in cmpa-d encoding a hco(3)(-)transporter with a transposon inactivation library, and we recovered mutants unable to take up hco(3)(-) and grow in low co(2) at ph 9.0. they are all tagged within slr1512 (designated sbta). we show that sbta-mediated transport is induced by low co(2), requires na(+), and plays the major role in ... | 2002 | 11904298 |
| cyanophycin production in a phycoerythrin-containing marine synechococcus strain of unusual phylogenetic affinity. | thirty-two strains of phycoerythrin-containing marine picocyanobacteria were screened for the capacity to produce cyanophycin, a nitrogen storage compound synthesized by some, but not all, cyanobacteria. we found that one of these strains, synechococcus sp. strain g2.1 from the arabian sea, was able to synthesize cyanophycin. the cyanophycin extracted from the cells was composed of roughly equimolar amounts of arginine and aspartate (29 and 35 mol%, respectively), as well as a small amount of gl ... | 2002 | 11916695 |
| evolution of sucrose synthesis. | cyanobacteria and proteobacteria (purple bacteria) are the only prokaryotes known to synthesize sucrose (suc). suc-p synthase, suc-phosphatase (spp), and suc synthase activities have previously been detected in several cyanobacteria, and genes coding for suc-p synthase (sps) and suc synthase (sus) have been cloned from synechocystis sp. pcc 6803 and anabaena (nostoc) spp., respectively. an open reading frame in the synechocystis genome encodes a predicted 27-kd polypeptide that shows homology to ... | 2002 | 11950997 |
| dynamic characteristics of prochlorococcus and synechococcus consumption by bacterivorous nanoflagellates. | we compared the characteristics of ingestion of prochlorococcus and synechococcus by the marine heterotrophic nanoflagellate pseudobodo sp. and by a mixed nanoflagellate culture (around 3 microm in size) obtained from an open sea oligotrophic area. maximum ingestion rate on synechococcus (2.7 syn flagellate(-1) h(-1)) was reached at concentrations of 5 x 10(5) syn ml(-1) and decreased between 6 x 10(5) and 1.5 x 10(6) syn ml(-1). in order to validate laboratory data, one set of data on synechoco ... | 2002 | 12037612 |
| diel patterns of uvbr-induced dna damage in picoplankton size fractions from the gulf of aqaba, red sea. | this study focuses on the impact of natural levels of uvbr (ultraviolet-b radiation: 280 to 315 nm) on bacterio- and phytoplankton (<10 microm) from the gulf of aqaba, red sea. incident biologically effective doses (beds) and attenuation of biologically effective radiation in the water column were measured using a dna biodosimeter. uvbr-induced dna damage was measured as cyclobutane pyrimidine dimers (cpds), using an antibody directed to cpds followed by chemiluminescent detection. depth profile ... | 2002 | 12060864 |
| expression studies of two paralogous ppa genes encoding distinct family i pyrophosphatases in marine unicellular cyanobacteria reveal inactivation of the typical cyanobacterial gene. | genome sequence analyses revealed the occurrence of two paralogous ppa genes potentially encoding distinct family i inorganic pyrophosphatases (sppases, ec3.6.1.1) in the marine unicellular cyanobacteria prochlorococcus marinus strains med4 and mit9313 and synechococcus sp. wh8102. protein sequence alignment and phylogenetic analysis indicated that the ppa gene proper of cyanobacteria (ppa1) encodes a presumably inactive mutant enzyme whereas the second gene (ppa2) might encode an active sppase ... | 2002 | 12127978 |
| conserved and variable domains within divergent rnase p rna gene sequences of prochlorococcus strains. | rnase p rna gene (rnpb) sequences were pcr-amplified from different members of the prochlorococcus group. aligned nucleotide sequences revealed a variance of up to 27% for rnpb. comparative secondary structure analysis showed that domains p12, p18 and p19 of these novel ribozyme sequences in particular are highly divergent. thus, these regions in rnase p rna might serve as potential targets for deoxyoligonucleotide primers for the identification of specific genotypes of prochlorococcus and for p ... | 2002 | 12148654 |
| the signal transducer p(ii) and bicarbonate acquisition in prochlorococcus marinus pcc 9511, a marine cyanobacterium naturally deficient in nitrate and nitrite assimilation. | the amino acid sequence of the signal transducer p(ii) (glnb) of the oceanic photosynthetic prokaryote prochlorococcus marinus strain pcc 9511 displays a typical cyanobacterial signature and is phylogenetically related to all known cyanobacterial glnb genes, but forms a distinct subclade with two other marine cyanobacteria. p(ii) of p. marinus was not phosphorylated under the conditions tested, despite its highly conserved primary amino acid sequence, including the seryl residue at position 49, ... | 2002 | 12177334 |
| photoacclimation of prochlorococcus sp. (prochlorophyta) strains isolated from the north atlantic and the mediterranean sea. | two atlantic (sarg and natl1) strains and one mediterranean (med) strain of prochlorococcus sp., a recently discovered marine, free-living prochlorophyte, were grown over a range of "white" irradiances (lg) and under low blue light to examine their photoacclimation capacity. all three strains contained divinyl (dv) chlorophylls (chl) a and b, both distinguishable from "normal" chls by their red-shifted blue absorption maximum, a chl c-like pigment at low concentration, zeaxanthin, and [alpha]-ca ... | 1993 | 12231684 |
| analysis of the hli gene family in marine and freshwater cyanobacteria. | certain cyanobacteria thrive in natural habitats in which light intensities can reach 2000 micromol photon m(-2) s(-1) and nutrient levels are extremely low. recently, a family of genes designated hli was demonstrated to be important for survival of cyanobacteria during exposure to high light. in this study we have identified members of the hli gene family in seven cyanobacterial genomes, including those of a marine cyanobacterium adapted to high-light growth in surface waters of the open ocean ... | 2002 | 12399037 |
| isolation of the gene for the b12-dependent ribonucleotide reductase from anabaena sp. strain pcc 7120 and expression in escherichia coli. | the gene for ribonucleotide reductase from anabaena sp. strain pcc 7120 was identified and expressed in escherichia coli. this gene codes for a 1,172-amino-acid protein that contains a 407-amino-acid intein. the intein splices itself from the protein when it is expressed in e. coli, yielding an active ribonucleotide reductase of 765 residues. the mature enzyme was purified to homogeneity from e. coli extracts. anabaena ribonucleotide reductase is a monomer with a molecular weight of approximatel ... | 2002 | 12426342 |
| synchronized expression of ftsz in natural prochlorococcus populations of the red sea. | the expression of ftsz, encoding the initiating protein of the prokaryotic cell division was analysed in natural prochlorococcus populations in the gulf of aqaba, northern red sea. during the seasonal prochlorococcus bloom in september 2000, picoplankton was collected from the deep chlorophyll maximum (dcm) at 2-4 h intervals over 3 consecutive days. flow cytometric measurements as well as dna sequence analyses showed that prochlorococcus was the dominant photosynthetic organism. cell densities ... | 2002 | 12460272 |
| co2 concentrating mechanisms in cyanobacteria: molecular components, their diversity and evolution. | cyanobacteria have evolved an extremely effective single-cell co(2) concentrating mechanism (ccm). recent molecular, biochemical and physiological studies have significantly extended current knowledge about the genes and protein components of this system and how they operate to elevate co(2) around rubisco during photosynthesis. the ccm components include at least four modes of active inorganic carbon uptake, including two bicarbonate transporters and two co(2) uptake systems associated with the ... | 2003 | 12554704 |
| high rate of uptake of organic nitrogen compounds by prochlorococcus cyanobacteria as a key to their dominance in oligotrophic oceanic waters. | direct evidence that marine cyanobacteria take up organic nitrogen compounds in situ at high rates is reported. about 33% of the total bacterioplankton turnover of amino acids, determined with a representative [(35)s]methionine precursor and flow sorting, can be assigned to prochlorococcus spp. and 3% can be assigned to synechococcus spp. in the oligotrophic and mesotrophic parts of the arabian sea, respectively. this finding may provide a mechanism for prochlorococcus' competitive dominance ove ... | 2003 | 12571062 |
| ecosystem-dependent adaptive radiations of picocyanobacteria inferred from 16s rrna and its-1 sequence analysis. | small, coccoid and rod-shaped synechococcus-type cyanobacteria with either phycoerythrin or phycocyanin as major accessory pigments were isolated from several large, temperate-zone lakes and the brackish baltic sea. the picocyanobacteria had two ribosomal operons with a long internal transcribed spacer (its-1) separating the 16s rdna and 23s rdna. a 16s rrna-based phylogenetic analysis assigned all isolates to the picophytoplankton clade [sensu urbach, e., scanlan, d. j., distel, d. l., waterbur ... | 2003 | 12576595 |
| phages of the marine cyanobacterial picophytoplankton. | cyanobacteria of the genera synechococcus and prochlorococcus dominate the prokaryotic component of the picophytoplankton in the oceans. it is still less than 10 years since the discovery of phages that infect marine synechococcus and the beginning of the characterisation of these phages and assessment of their ecological impact. estimations of the contribution of phages to synechococcus mortality are highly variable, but there is clear evidence that phages exert a significant selection pressure ... | 2003 | 12697340 |
| a novel type of lycopene epsilon-cyclase in the marine cyanobacterium prochlorococcus marinus med4. | chlorophyll- b-possessing cyanobacteria of the genus prochlorococcus share the presence of high amounts of alpha- and beta-carotenoids with green algae and higher plants. the branch point in carotenoid biosynthesis is the cyclization of lycopene, for which in higher plants two distinct enzymes are required, epsilon- and beta-lycopene cyclase. all cyanobacteria studied so far possess a single beta-cyclase. here, two different prochlorococcus sp. med4 genes were functionally identified by heterolo ... | 2003 | 12712234 |
| glutamine synthetase from the marine cyanobacteria prochlorococcus spp: characterization, phylogeny and response to nutrient limitation. | the regulation of glutamine synthetase (ec 6.3.1.2) from prochlorococcus was previously shown to exhibit unusual features: it is not upregulated by nitrogen starvation and it is not inactivated by darkness (el alaoui et al. (2001) appl environ microbiol 67: 2202-2207). these are probably caused by adaptations to oligotrophic environments, as confirmed in this work by the marked decrease in the enzymatic activity when cultures were subjected to iron or phosphorus starvation. in order to further u ... | 2003 | 12713467 |
| experimental and computational analysis of transcriptional start sites in the cyanobacterium prochlorococcus med4. | in contrast to certain model eubacteria, little is known as to where transcription is initiated in the genomes of cyanobacteria, which are largely distinct from other prokaryotes. in this work, 25 transcription start sites (tss) of 21 different genes of prochlorococcus sp. med4 were determined experimentally. the data suggest more than one tss for the genes ftsz, peth, psbd and ntca. in contrast, the rbcl-rbcs operon encoding ribulose 1,5-bisphosphate carboxylase/oxygenase lacks a detectable pro ... | 2003 | 12771216 |
| toward an understanding of cell growth and the cell division cycle of unicellular photoautotrophic cyanobacteria. | the cell division cycle of synechococcus sp. strain pcc 6301 in light is characterized by the sequential and orderly appearance of macromolecular synthesis periods. in the dark, macromolecular synthesis and cell division are severely curtailed. when dark-incubated cultures are reexposed to light, a new cell cycle is initiated. the pattern of the cell events displayed by synechococcus in light and the absence of sustained growth in dark incubation conditions suggests that light-activated regulato ... | 2003 | 12785715 |
| structure of a photosystem ii supercomplex isolated from prochloron didemni retaining its chlorophyll a/b light-harvesting system. | prochlorophytes are a class of cyanobacteria that do not use phycobiliproteins as light-harvesting systems, but contain chlorophyll (chl) a/b-binding pcb proteins. recently it was shown that pcb proteins form an 18-subunit light-harvesting antenna ring around the photosystem i (psi) trimeric reaction center complex of the prochlorophyte prochlorococcus marinus ss120. here we have investigated whether the symbiotic prochlorophyte prochloron didemni also contains the same supermolecular complex. u ... | 2003 | 12837938 |
| analysis of natural populations of prochlorococcus spp. in the northern red sea using phycoerythrin gene sequences. | marine cyanobacteria of the genus prochlorococcus belong to one of two ecotypes that are specifically adapted to either low light (ll) or high light (hl) conditions. previous analyses of the differences in pigmentation and gene complement revealed that ll-adapted ecotypes carry a gene cluster to produce a functional phycoerythrin, whereas in the fully sequenced genome of the hl-adapted strain med4, only a single and free-standing cpeb gene occurs. this gene encodes a derived form of beta-phycoer ... | 2003 | 12871235 |
| genome sequence of the cyanobacterium prochlorococcus marinus ss120, a nearly minimal oxyphototrophic genome. | prochlorococcus marinus, the dominant photosynthetic organism in the ocean, is found in two main ecological forms: high-light-adapted genotypes in the upper part of the water column and low-light-adapted genotypes at the bottom of the illuminated layer. p. marinus ss120, the complete genome sequence reported here, is an extremely low-light-adapted form. the genome of p. marinus ss120 is composed of a single circular chromosome of 1,751,080 bp with an average g+c content of 36.4%. it contains 1,8 ... | 2003 | 12917486 |
| genome divergence in two prochlorococcus ecotypes reflects oceanic niche differentiation. | the marine unicellular cyanobacterium prochlorococcus is the smallest-known oxygen-evolving autotroph. it numerically dominates the phytoplankton in the tropical and subtropical oceans, and is responsible for a significant fraction of global photosynthesis. here we compare the genomes of two prochlorococcus strains that span the largest evolutionary distance within the prochlorococcus lineage and that have different minimum, maximum and optimal light intensities for growth. the high-light-adapte ... | 2003 | 12917642 |
| cyanophages infecting the oceanic cyanobacterium prochlorococcus. | prochlorococcus is the numerically dominant phototroph in the tropical and subtropical oceans, accounting for half of the photosynthetic biomass in some areas. here we report the isolation of cyanophages that infect prochlorococcus, and show that although some are host-strain-specific, others cross-infect with closely related marine synechococcus as well as between high-light- and low-light-adapted prochlorococcus isolates, suggesting a mechanism for horizontal gene transfer. high-light-adapted ... | 2003 | 12944965 |
| low-light-adapted prochlorococcus species possess specific antennae for each photosystem. | prochlorococcus, the most abundant genus of photosynthetic organisms, owes its remarkably large depth distribution in the oceans to the occurrence of distinct genotypes adapted to either low- or high-light niches. the pcb genes, encoding the major chlorophyll-binding, light-harvesting antenna proteins in this genus, are present in multiple copies in low-light strains but as a single copy in high-light strains. the basis of this differentiation, however, has remained obscure. here we show that th ... | 2003 | 12944966 |
| two-component systems in prochlorococcus med4: genomic analysis and differential expression under stress. | two-component signal transduction systems, composed of histidine sensory kinases and response regulators, constitute a key element of the mechanism by which bacteria sense and acclimatize to changes in their environment. the availability of whole genome sequences permits a detailed analysis of these genes in cyanobacteria. in the present paper, we focus mainly on prochlorococcus med4, a strain adapted to surface oceanic conditions, for which six putative response regulators (rer) and five putati ... | 2003 | 13129619 |
| photophysical properties of prochlorococcus marinus ss120 divinyl chlorophylls and phycoerythrin in vitro and in vivo. | prochlorococcus marinus ss120 is an ecologically important and biochemically intriguing marine cyanobacterium. in addition to divinyl chlorophylls (dv-chls) a and b it possesses a particular form of phycoerythrin (pe), but no other phycobilins and therefore no complete phycobilisomes. here, a spectroscopic characterisation of these dv-chls and pe is provided. comparison of fluorescence quantum yields, excited state lifetimes and absorption characteristics indicate similar light-harvesting proper ... | 2003 | 14550550 |
| prokaryotic origins for the mitochondrial alternative oxidase and plastid terminal oxidase nuclear genes. | the mitochondrial alternative oxidase is a diiron carboxylate quinol oxidase (dox) found in plants and some fungi and protists, but not animals. the plastid terminal oxidase is distantly related to alternative oxidase and is most likely also a dox protein. database searches revealed that the alpha-proteobacterium novosphingobium aromaticivorans and the cyanobacteria nostoc sp. pcc7120, synechococcus sp. wh8102 and prochlorococcus marinus subsp. pastoris ccmp1378 each possess a dox homolog. each ... | 2003 | 14675750 |
| a novel evolutionary lineage of carbonic anhydrase (epsilon class) is a component of the carboxysome shell. | a significant portion of the total carbon fixed in the biosphere is attributed to the autotrophic metabolism of prokaryotes. in cyanobacteria and many chemolithoautotrophic bacteria, co(2) fixation is catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), most if not all of which is packaged in protein microcompartments called carboxysomes. these structures play an integral role in a cellular co(2)-concentrating mechanism and are essential components for autotrophic growth. here ... | 2004 | 14729686 |
| operon prediction by comparative genomics: an application to the synechococcus sp. wh8102 genome. | we present a computational method for operon prediction based on a comparative genomics approach. a group of consecutive genes is considered as a candidate operon if both their gene sequences and functions are conserved across several phylogenetically related genomes. in addition, various supporting data for operons are also collected through the application of public domain computer programs, and used in our prediction method. these include the prediction of conserved gene functions, promoter m ... | 2004 | 15096577 |
| metal speciation dynamics and bioavailability: bulk depletion effects. | under conditions of bulk depletion, the speciation and bioavailability of trace metals must be considered at two different time scales: (i) the time scale of the biouptake flux, as determined by diffusion of the bioactive free metal, dissociation of the bioinactive complex species, and the internalization rate; and (ii) the time scale of depletion of the bulk medium. the implications of these two time scales for the speciation dynamics are discussed in terms of experimental conditions. the geome ... | 2004 | 15116846 |
| effects of high light on transcripts of stress-associated genes for the cyanobacteria synechocystis sp. pcc 6803 and prochlorococcus med4 and mit9313. | cyanobacteria constitute an ancient, diverse and ecologically important bacterial group. the responses of these organisms to light and nutrient conditions are finely controlled, enabling the cells to survive a range of environmental conditions. in particular, it is important to understand how cyanobacteria acclimate to the absorption of excess excitation energy and how stress-associated transcripts accumulate following transfer of cells from low- to high-intensity light. in this study, quantitat ... | 2004 | 15133090 |
| global features of sequences of bacterial chromosomes, plasmids and phages revealed by analysis of oligonucleotide usage patterns. | oligonucleotide frequencies were shown to be conserved signatures for bacterial genomes, however, the underlying constraints have yet not been resolved in detail. in this paper we analyzed oligonucleotide usage (ou) biases in a comprehensive collection of 155 completely sequenced bacterial chromosomes, 316 plasmids and 104 phages. | 2004 | 15239845 |
| transfer of photosynthesis genes to and from prochlorococcus viruses. | comparative genomics gives us a new window into phage-host interactions and their evolutionary implications. here we report the presence of genes central to oxygenic photosynthesis in the genomes of three phages from two viral families (myoviridae and podoviridae) that infect the marine cyanobacterium prochlorococcus. the genes that encode the photosystem ii core reaction center protein d1 (psba), and a high-light-inducible protein (hlip) (hli) are present in all three genomes. both myoviruses c ... | 2004 | 15256601 |
| genetic organization of the psbad region in phages infecting marine synechococcus strains. | the discovery of the genes psba and psbd, encoding the d1 and d2 core components of the photosynthetic reaction center psii (photosystem ii), in the genome of the bacteriophage s-pm2 (a cyanomyovirus) that infects marine cyanobacteria begs the question as to how these genes were acquired. in an attempt to answer this question, it was established that the occurrence of the genes is widespread among marine cyanomyovirus isolates and may even extend to podoviruses. the phage psba genes fall into a ... | 2004 | 15263091 |
| natural community structure of cyanobacteria in the south china sea as revealed by rpoc1 gene sequence analysis. | to examine the community structure of cyanobacterial populations of the south china sea on the surface and at depth of 80 m. | 2004 | 15355538 |
| cyanophage infection and photoinhibition in marine cyanobacteria. | members of two cyanobacterial genera, synechococcus and prochlorococcus, are dominant within the prokaryotic component of the picophytoplankton and contribute significantly to global photosynthetic productivity. these organisms are known to be susceptible to infection by bacteriophages (viruses that infect bacteria) and it is believed that phage infection in the oceans has exerted selective pressures on the evolution of both phage and host and continues to influence community structure. understa ... | 2004 | 15501648 |
| tetra: a web-service and a stand-alone program for the analysis and comparison of tetranucleotide usage patterns in dna sequences. | in the emerging field of environmental genomics, direct cloning and sequencing of genomic fragments from complex microbial communities has proven to be a valuable source of new enzymes, expanding the knowledge of basic biological processes. the central problem of this so called metagenome-approach is that the cloned fragments often lack suitable phylogenetic marker genes, rendering the identification of clones that are likely to originate from the same genome difficult or impossible. in such cas ... | 2004 | 15507136 |
| in vivo production of active nickel superoxide dismutase from prochlorococcus marinus mit9313 is dependent on its cognate peptidase. | metal-dependent superoxide dismutases (sods) with a specific requirement for a manganese or iron ion for catalytic activity and copper- and zinc-dependent enzymes are essential for detoxification of superoxide anion radicals. genome sequence analyses predict the existence of a nickel-dependent enzyme (nisod) as the unique sod in oxygen-evolving marine cyanobacteria. nisod activity was observed in escherichia coli when sodn and sodx (encoding a putative peptidase) from prochlorococcus marinus mit ... | 2004 | 15516600 |
| properties of overlapping genes are conserved across microbial genomes. | there are numerous examples from the genomes of viruses, mitochondria, and chromosomes that adjacent genes can overlap, sharing at least one nucleotide. overlaps have been hypothesized to be involved in genome size minimization and as a regulatory mechanism of gene expression. here we show that overlapping genes are a consistent feature (approximately one-third of all genes) across all microbial genomes sequenced to date, have homologs in more microbes than do non-overlapping genes, and are ther ... | 2004 | 15520290 |
| adaptive mechanisms of nitrogen and carbon assimilatory pathways in the marine cyanobacteria prochlorococcus. | prochlorococcus is an abundant marine cyanobacterium responsible for a significant part of global primary production. there exist various ecotypes adapted to conditions found along the water column, showing that largely modified photosynthetic apparatus efficiently harvest the light energy penetrating into their habitats. in view of the recent availability of three prochlorococcus genomes, we review here additional adaptive changes observed in nitrogen and carbon metabolism. | 2004 | 15567272 |
| development of a universal microarray based on the ligation detection reaction and 16s rrna gene polymorphism to target diversity of cyanobacteria. | the cyanobacteria are photosynthetic prokaryotes of significant ecological and biotechnological interest, since they strongly contribute to primary production and are a rich source of bioactive compounds. in eutrophic fresh and brackish waters, their mass occurrences (water blooms) are often toxic and constitute a high potential risk for human health. therefore, rapid and reliable identification of cyanobacterial species in complex environmental samples is important. here we describe the develop ... | 2004 | 15574913 |
| streamlined regulation and gene loss as adaptive mechanisms in prochlorococcus for optimized nitrogen utilization in oligotrophic environments. | prochlorococcus is one of the dominant cyanobacteria and a key primary producer in oligotrophic intertropical oceans. here we present an overview of the pathways of nitrogen assimilation in prochlorococcus, which have been significantly modified in these microorganisms for adaptation to the natural limitations of their habitats, leading to the appearance of different ecotypes lacking key enzymes, such as nitrate reductase, nitrite reductase, or urease, and to the simplification of the metabolic ... | 2004 | 15590777 |
| the occurrence of rapidly reversible non-photochemical quenching of chlorophyll a fluorescence in cyanobacteria. | cyanobacteria have previously been considered to differ fundamentally from plants and algae in their regulation of light harvesting. we show here that in fact the ecologically important marine prochlorophyte, prochlorococcus, is capable of forming rapidly reversible non-photochemical quenching of chlorophyll a fluorescence (npqf or qe) as are freshwater cyanobacteria when they employ the iron stress induced chlorophyll-based antenna, isia. for prochlorococcus, the capacity for npqf is greater in ... | 2005 | 15620726 |
| identification of a vinyl reductase gene for chlorophyll synthesis in arabidopsis thaliana and implications for the evolution of prochlorococcus species. | chlorophyll metabolism has been extensively studied with various organisms, and almost all of the chlorophyll biosynthetic genes have been identified in higher plants. however, only the gene for 3,8-divinyl protochlorophyllide a 8-vinyl reductase (dvr), which is indispensable for monovinyl chlorophyll synthesis, has not been identified yet. in this study, we isolated an arabidopsis thaliana mutant that accumulated divinyl chlorophyll instead of monovinyl chlorophyll by ethyl methanesulfonate mut ... | 2005 | 15632054 |
| accelerated evolution associated with genome reduction in a free-living prokaryote. | three complete genomes of prochlorococcus species, the smallest and most abundant photosynthetic organism in the ocean, have recently been published. comparative genome analyses reveal that genome shrinkage has occurred within this genus, associated with a sharp reduction in g+c content. as all examples of genome reduction characterized so far have been restricted to endosymbionts or pathogens, with a host-dependent lifestyle, the observed genome reduction in prochlorococcus is the first documen ... | 2005 | 15693943 |
| alternative oxidase and plastoquinol terminal oxidase in marine prokaryotes of the sargasso sea. | alternative oxidase (aox) represents a non-energy conserving branch in mitochondrial electron transport while plastoquinol terminal oxidase (ptox) represents a potential branch in photosynthetic electron transport. using a metagenomics dataset, we have uncovered numerous and diverse aox and ptox genes from the sargasso sea. sequence similarity, synteny and phylogenetic analyses indicate that the large majority of these genes are from prokaryotes. aox appears to be widely distributed among marine ... | 2005 | 15777727 |
| differential sunlight sensitivity of picophytoplankton from surface mediterranean coastal waters. | we tested the sensitivity of coastal picophytoplankton exposed to natural sunlight in short-term experiments. cell abundance and cell-specific chlorophyll fluorescence were significantly reduced in prochlorococcus spp. but not in synechococcus, whereas picoeukaryotes had an intermediate response. these results are the first direct evidence of a differential sensitivity to sunlight of these ubiquitous marine members of unicellular phytoplankton. | 2005 | 15812050 |
| three prochlorococcus cyanophage genomes: signature features and ecological interpretations. | the oceanic cyanobacteria prochlorococcus are globally important, ecologically diverse primary producers. it is thought that their viruses (phages) mediate population sizes and affect the evolutionary trajectories of their hosts. here we present an analysis of genomes from three prochlorococcus phages: a podovirus and two myoviruses. the morphology, overall genome features, and gene content of these phages suggest that they are quite similar to t7-like (p-ssp7) and t4-like (p-ssm2 and p-ssm4) ph ... | 2005 | 15828858 |
| ecotype diversity in the marine picoeukaryote ostreococcus (chlorophyta, prasinophyceae). | the importance of the cyanobacteria prochlorococcus and synechococcus in marine ecosystems in terms of abundance and primary production can be partially explained by ecotypic differentiation. despite the dominance of eukaryotes within photosynthetic picoplankton in many areas a similar differentiation has never been evidenced for these organisms. here we report distinct genetic [rdna 18s and internal transcribed spacer (its) sequencing], karyotypic (pulsed-field gel electrophoresis), phenotypic ... | 2005 | 15892704 |
| 16s rrna phylogeny of sponge-associated cyanobacteria. | phylogenetic analyses of 16s rrna sequences of sponge-associated cyanobacteria showed them to be polyphyletic, implying that they derived from multiple independent symbiotic events. most of the symbiont sequences were affiliated to a group of synechococcus and prochlorococcus species. however, other symbionts were related to different groups, such as the oscillatoriales. | 2005 | 16000832 |
| grazing impact of different heterotrophic nanoflagellates on eukaryotic (ostreococcus tauri) and prokaryotic picoautotrophs (prochlorococcus and synechococcus). | autotrophic picoplankton (<3 microm) composed of both prokaryotes and eukaryotes are the most abundant primary producers on earth. in this study we examined the ingestion of the picoeukaryote ostreococcus tauri by different marine heterotrophic nanoflagellates (hnf) with various morphologies, swimming and feeding behaviours. cultures of specific bacterivorous nanoflagellates (rhynchomonas nasuta, jakoba libera, and a culture of cafeteria sp./monosiga sp.) and natural nanoflagellate populations w ... | 2005 | 16011757 |
| coupling 16s-its rdna clone libraries and automated ribosomal intergenic spacer analysis to show marine microbial diversity: development and application to a time series. | we outline an approach to simultaneously assess multilevel microbial diversity patterns utilizing 16s-its rdna clone libraries coupled with automated ribosomal intergenic spacer analysis (arisa). sequence data from 512 clones allowed estimation of arisa fragment lengths associated with bacteria in a coastal marine environment. we matched 92% of arisa peaks (each comprising >1% total amplified product) with corresponding lengths from clone libraries. these peaks with putative identification accou ... | 2005 | 16104869 |