The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
Anthony W. D. Larkum - One of the best experts on this subject based on the ideXlab platform.
-
sequence of prochloron didemni atpbe and the inference of chioroplast origins endosymbiosis Prochlorophyta phylogeny atp synthase cyanobacteria
2016Co-Authors: Peter J Lockhart, T J Beanlandt, C J Howet, Anthony W. D. LarkumAbstract:The prochlorophytes, oxygenic photosyn- thetic prokaryotes containing chlorophylls a and b, have been put forward as descended from the organisms that gave rise to chloroplasts of green planis and algae by endosymbiosis, although this has always been controversial. To assess the phylogenetic position of the prochlorophyte Prochloron di- demni, we have cloned and sequenced its atpBE genes. Phylo- genetic inference under a range of models gives moderate to strong support for a cyanobacterial grouping rather than a chloroplast one. Possible systematic errors in this and previous analyses of prochlorophyte sequences are discussed. 1. ~~~~~2. 3.
-
Sequence of Prochloron didemni atpBE and the inference of chioroplast origins (endosymbiosis/Prochlorophyta/phylogeny/ATP synthase/cyanobacteria)
2016Co-Authors: P. J. Lockhart, T J Beanlandt, C J Howet, Anthony W. D. LarkumAbstract:The prochlorophytes, oxygenic photosyn- thetic prokaryotes containing chlorophylls a and b, have been put forward as descended from the organisms that gave rise to chloroplasts of green planis and algae by endosymbiosis, although this has always been controversial. To assess the phylogenetic position of the prochlorophyte Prochloron di- demni, we have cloned and sequenced its atpBE genes. Phylo- genetic inference under a range of models gives moderate to strong support for a cyanobacterial grouping rather than a chloroplast one. Possible systematic errors in this and previous analyses of prochlorophyte sequences are discussed. 1. ~~~~~2. 3.
-
Microbial diversity of biofilm communities in microniches associated with the didemnid ascidian Lissoclinum patella
The ISME Journal, 2012Co-Authors: Lars Behrendt, Anthony W. D. Larkum, Erik Trampe, Anders Norman, Søren J Sørensen, Michael KühlAbstract:We assessed the microbial diversity and microenvironmental niche characteristics in the didemnid ascidian Lissoclinum patella using 16S rRNA gene sequencing, microsensor and imaging techniques. L. patella harbors three distinct microbial communities spatially separated by few millimeters of tunic tissue: (i) a biofilm on its upper surface exposed to high irradiance and O_2 levels, (ii) a cloacal cavity dominated by the prochlorophyte Prochloron spp. characterized by strong depletion of visible light and a dynamic chemical microenvironment ranging from hyperoxia in light to anoxia in darkness and (iii) a biofilm covering the underside of the animal, where light is depleted of visible wavelengths and enriched in near-infrared radiation (NIR). Variable chlorophyll fluorescence imaging demonstrated photosynthetic activity, and hyperspectral imaging revealed a diversity of photopigments in all microhabitats. Amplicon sequencing revealed the dominance of cyanobacteria in all three layers. Sequences representing the chlorophyll d containing cyanobacterium Acaryochloris marina and anoxygenic phototrophs were abundant on the underside of the ascidian in shallow waters but declined in deeper waters. This depth dependency was supported by a negative correlation between A. marina abundance and collection depth, explained by the increased attenuation of NIR as a function of water depth. The combination of microenvironmental analysis and fine-scale sampling techniques used in this investigation gives valuable first insights into the distribution, abundance and diversity of bacterial communities associated with tropical ascidians. In particular, we show that microenvironments and microbial diversity can vary significantly over scales of a few millimeters in such habitats; which is information easily lost by bulk sampling.
-
Light-harvesting chlorophyll c-like pigment inProchloron (endosymbiosis/phylogeny/Prochlorophyta)
2007Co-Authors: Anthony W. D. Larkum, C. Scaramuzzi, G. C. Cox, R. G. HillertAbstract:Achlorophyll c-like pigment, similar tomag- nesium-3,8-divinyl pheoporphyrin asmonomethyl ester, has beenisolated fromProchloron sp.obtained fromfive species of didemnid ascidians fromtheGreatBarrier Reef, Australia, andfromPalau, Micronesia. Thepigment represents 4-15%of thetotal chlorophyll content andisshowntofunction ina light-harvesting pigment protein complex ofProchloron. The observation that all ofthemajor chlorophylls (a+b+c) function inalight-harvesting role inProchloron andpossibly inother prochlorophytes isdiscussed intermsofthephylogeny ofthe prochlorophytes.
-
light harvesting chlorophyll c like pigment inprochloron endosymbiosis phylogeny Prochlorophyta
2007Co-Authors: Anthony W. D. Larkum, C. Scaramuzzi, G. C. Cox, R. G. HillertAbstract:Achlorophyll c-like pigment, similar tomag- nesium-3,8-divinyl pheoporphyrin asmonomethyl ester, has beenisolated fromProchloron sp.obtained fromfive species of didemnid ascidians fromtheGreatBarrier Reef, Australia, andfromPalau, Micronesia. Thepigment represents 4-15%of thetotal chlorophyll content andisshowntofunction ina light-harvesting pigment protein complex ofProchloron. The observation that all ofthemajor chlorophylls (a+b+c) function inalight-harvesting role inProchloron andpossibly inother prochlorophytes isdiscussed intermsofthephylogeny ofthe prochlorophytes.
Ralph A Lewin - One of the best experts on this subject based on the ideXlab platform.
-
prochloron a microbial enigma
2011Co-Authors: Ralph A Lewin, Lanna ChengAbstract:1.Introduction.- 2. Collection and Handling of Prochloron and Its Hosts.- Collection and Handling.- Didemnum molle.- Diplosoma virens.- Diplosoma similis.- Trididemnum cyclops.- Lissoclinum punctatum.- Lissoclinum voeltzkowi.- Lissoclinum patella.- Treatment of Prochloron cells.- Conclusion.- 3. Prochloron in Symbiosis.- Photosynthesis.- Translocation.- Formation of the Symbiosis.- Biochemical Interactions between the Symbionts.- Other Interactions between the Symbionts.- References.- 4. Physiological and Cellular Features of Prochloron.- Photosynthetic Features of Prochloron.- Carbon Metabolism.- Photosynthesis-Irradiance Relationships.- Respiratory Behavior and Carbon Balance in Prochloron.- Properties of the Photosynthetic Pigments and Membranes of Prochloron.- Pigments and Pigment-Protein Complexes.- Why Has Prochloron a Chlorophyll a + b Harvesting System?.- Physiology of the Prochloron-Ascidian Association.- Photosynthesis and Respiration of Symbiotic Didemnids.- Nitrogen Assimilation.- Obligate Nature of Symbiosis.- Some Suggested Physiological Requirements for the Culture of Prochloron.- Conclusion.- References.- 5. Biochemical Features of Prochloron.- General Features of Enzyme Isolation.- Enzymes of Photosynthetic Carbon Metabolism.- Ribulose 1,5-Bisphosphate Carboxylase-Oxygenase.- Phosphoribulose Kinase.- Enzymes of Glucan Synthesis and Storage Carbohydrates.- Lipophilic Components.- Lipid and Sterol Composition.- Pigments.- Properties of Membrane Fractions.- Miscellaneous Compounds and Metabolic Investigations.- Proteins and Amino Acids.- Cell Wall Components.- Nucleic Acids.- Nitrogen Metabolism.- Conclusion.- References.- 6. Phylogenetic Considerations of Prochloron.- Phylogenetic Position.- Phylogentic Rank.- Possible Relationship to Chloroplasts.- References.- 7. The Cytology of Prochloron.- The Cell Wall.- Thylakoids.- Inclusions.- Nucleic Acids.- Conclusion.- References.- 8. A Status Report on Prochlorothrix hollandica a Free-Living Prochlorophyte.- Epilogue.- Author Index.
-
Prochlorophyta – a matter of class distinctions
Photosynthesis Research, 2002Co-Authors: Ralph A LewinAbstract:Prochloron (a marine symbiont) and Prochlorothrix (from freshwater plankton) contain chlorophylls a and b ; Prochlorococcus (common in marine picoplankton) contains divinyl-chlorophylls a and b . Like cyanophytes they are all clearly photosynthetic prokaryotes, but since they contain no blue or red bilin pigment they were assigned to a new algal sub-class, the Prochlorophyta. However, since their possible phylogenetic relationships to ancestral green-plant chloroplasts have not received support from molecular biology, it now seems expedient to consider them as aberrant cyanophytes.
-
Prochlorophyta - a matter of class distinctions.
Photosynthesis research, 2002Co-Authors: Ralph A LewinAbstract:Prochloron (a marine symbiont) and Prochlorothrix (from freshwater plankton) contain chlorophylls a and b; Prochlorococcus (common in marine picoplankton) contains divinyl-chlorophylls a and b. Like cyanophytes they are all clearly photosynthetic prokaryotes, but since they contain no blue or red bilin pigment they were assigned to a new algal sub-class, the Prochlorophyta. However, since their possible phylogenetic relationships to ancestral green-plant chloroplasts have not received support from molecular biology, it now seems expedient to consider them as aberrant cyanophytes.
-
© 2002 Kluwer Academic Publishers. Printed in the Netherlands. 59 Personal perspective Prochlorophyta – a matter of class distinctions
2001Co-Authors: Ralph A LewinAbstract:Prochloron (a marine symbiont) and Prochlorothrix (from freshwater plankton) contain chlorophylls a and b; Prochlorococcus (common in marine picoplankton) contains divinyl-chlorophylls a and b. Like cyanophytes they are all clearly photosynthetic prokaryotes, but since they contain no blue or red bilin pigment they were assigned to a new algal sub-class, the Prochlorophyta. However, since their possible phylogenetic relationships to ancestral green-plant chloroplasts have not received support from molecular biology, it now seems expedient to consider them as aberrant cyanophytes
-
intracellular symbiosis of a photosynthetic prokaryote prochloron sp in a colonial ascidian
Invertebrate Biology, 1996Co-Authors: Euichi Hirose, Lanna Cheng, Tadashi Maruyama, Ralph A LewinAbstract:Cells of a symbiotic prokaryote, Prochloron sp., in colonies of a tropical ascidian, Lissoclinum punctatum, occur not only outside but also inside cells of the host. Cells of these photosynthetic symbionts of ascidians have previously been reported only extracellularly. The intracellular and extracellular symbionts do not differ morphologically. The host cells carrying the symbionts are freely distributed in the ascidian tunic. They probably endocytize the symbionts and then retain them within a vacuole. Since the intracellular prokaryotes showed no evidence of rejection or degeneration, this association between tunic phagocytes of L. punctatum and cells of Prochloron sp. seems to constitute a stable symrnbiosis, comparable to the postulated ancestral association between heterotrophic cells and the photosynthetic prokaryotes which gave rise to chloroplasts. Additional key words: algae, cyanobacteria, plastid evolution, prochlorophytes, tunicates Chloroplasts are photosynthetic organelles found in all photosynthetic eukaryotes. There is now convincing evidence from molecular biological studies on 16S-rRNA and RNA polymerase subunit (rpo Cl) and ribulose-bisphosphate carboxylase genes (Seewaldt & Stackebrandt 1982; Palenik & Haselkorn 1992; Urbach et al. 1992; Shimada et al. 1995) that these organelles originated from prokaryotic photosynthetic endosymbionts (cyanobacteria) engulfed and retained by heterotrophic host cells (Lewin 1981; Margulis 1981). Symbiotic photosynthetic prokaryotes are therefore of interest in relation to the evolution of chloroplasts. Prochloron is a genus of unicellular prokaryotes with the same chlorophyll pigments, chl a and b, as those in the chloroplasts of green algae and all other green plants (Lewin 1976). Prochlorophyta/Prochlorales was originally established (Lewin 1976, 1977; Florenzano et al. 1986) for prokaryotes that bear chl. a and b, lack bilin pigments, and generate oxygen in photosynthesis; molecular phylogenetic studies, however, indicate that this is a polyphyletic group whose members arose within the cyanobacterial radiation and should be treated as members of Cyanophyta/Cyanobacteria (Palenik & Haselkorn 1992; Urbach et al. 1992; Shimada et al. 1995). Cells of Prochloron occur in coral reef areas, almost exclusively as symbionts of colonial didemnid ascidians (Lewin & Cheng 1989). There the symbionts are normally associated with external or internal colony surfaces, but outside the host cells. Prochloron didemni LEWIN 1977 was originally described from the outer surfaces of didemnid colonies; but since no prochloron cells have been cultured in vitro, and specific distinctions remain to be established, we will refer to the symbionts in this paper simply as Prochloron sp. We present here the first report of Prochloron sp. as an intracellular symbiont in a didemnid ascidian, Lissoclinum punctatum KOTT 1977. Recent molecular biological data (Palenik & Haselkorn 1992; Urbach et al. 1992) indicate that the phylogenetic affinities of chloroplasts are closer to other cyanobacteria than to Prochloron, but we suggest that intracellular Prochloron can be regarded as a model of the ancestral green plastid.
Daniel Vaulot - One of the best experts on this subject based on the ideXlab platform.
-
coexistence of phycoerythrin and a chlorophyll a b antenna in a marine prokaryote
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Wolfgang R. Hess, G W M Van Der Staay, Frederic Partensky, Jose Manuel Garciafernandez, Thomas Borner, Daniel VaulotAbstract:Abstract 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 the alpha subunit designate it as a novel PE type, which we propose naming PE-III. P. marinus is the sole prokaryotic organisms known so far that contains chlorophylls a and b as well as phycobilins. These data strongly suggest that the common ancestor of prochlorophytes and the Synechococcus cyanobacteria contained phycobilins. Flow cytometric data from the tropical Pacific Ocean provide evidence that deep populations of Prochlorococcus possess low amounts of a PE-like pigment, which could serve either in light harvesting or nitrogen storage or both.
-
High degree of genetic variation in Prochlorococcus (Prochlorophyta) revealed by RFLP analysis
European Journal of Phycology, 1996Co-Authors: David J. Scanlan, Frederic Partensky, Wolfgang R. Hess, Julie Newman, Daniel VaulotAbstract:A genetic characterization of nine strains of Prochlorococcus originating from various depths of the Mediterranean Sea, the Sargasso Sea, the North and the tropical Atlantic Ocean and the Pacific Ocean was performed by restriction fragment length polymorphism (RFLP) mapping using probes for rbcL, rbcS, psbA and woxA. This study revealed extensive genetic variation among strains, which were grouped into two distinct clusters. Unexpectedly, with one exception (TATL1 strain), the strains clustered by isolation depth (i.e. near surface versus deep isolates) rather than by geographic origin. These relationships were confirmed by secondary RFLP analysis of psbA amplification products using Prochlorococcus-specific polymerase chain reaction (PCR) primers.
-
Characterization of the single psbA gene of Prochlorococcus marinus CCMP 1375 (Prochlorophyta)
Plant Molecular Biology, 1995Co-Authors: Wolfgang R. Hess, Frederic Partensky, Andreas Weihe, Susan Loiseaux-de Goër, Daniel VaulotAbstract: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. Phylogenetic trees suggested the D1-1 iso -form from Synechococcus PCC 7942 as the next related D1 protein and place P. Marinus separately from Prochlorothrix hollandica among the cyanobacteria.
-
photoacclimation of prochlorococcus sp Prochlorophyta strains isolated from the north atlantic and the mediterranean sea
Plant Physiology, 1993Co-Authors: Frederic Partensky, Nicolas Hoepffner, Osvaldo Ulloa, Daniel VaulotAbstract: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]-carotene. The presence of two phaeophytin b peaks in acidified extracts from both Atlantic strains grown at high lg suggests that these strains also had a normal Chl b-like pigment. In these strains, the total Chl b to DV-Chl a molar ratio decreased from about 1 at 7.5 [mu]mol quanta m-2 s-1 to 0.4 to 0.5 at 133 [mu]mol quanta m-2 s-1. In contrast, the MED strain always had a low DV-Chl b to DV-Chl a molar ratio, ranging between 0.13 at low lg and 0.08 at high lg. The discrepancies between the Atlantic and MED strains could result from differences either in the number of light-harvesting complexes (LHC) II per photosystem II or in the Chl b-binding capacity of the apoproteins constituting LHC II. Photosynthesis was saturated at approximately 5 fg C(fg Chl)-1 h-1 or 6 fg C cell-1 h-1, and growth was saturated at approximately 0.45 d-1 for both MED and SARG strains at 18[deg]C, but saturating irradiances differed between strains. Atlantic strains exhibited increased light-saturated rates and quantum yield for carbon fixation under blue light.
-
Photoacclimation of Prochlorococcus sp. (Prochlorophyta) Strains lsolated from the North Atlantic and the Mediterranean Sea
1993Co-Authors: Frederic Partensky, Daniel Vaulot, Nicolas Hoepffner, Osvaldo Ulloa, K W William, Nova ScotiaAbstract:irradiances (I,) 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 a-carotene. The presence of two phaeophytin b peaks in acidified extracts from both Atlantic strains grown at high I, suggests that these strains also had a normal Chl b-like pigment. In these strains, the total Chl b to DVChl a molar ratio decreased from about 1 at 7.5 pmol quanta m-’ s-’ to 0.4 to 0.5 at 133 pmol quanta me’s-’. In contrast, the MED strain always had a low DV-Chl b to DV-Chl a molar ratio, ranging between 0.13 at low I, and 0.08 at high I,. The discrepancies between the Atlantic and MED strains could result from differences either in the number of light-harvesting complexes (LHC) II per photosystem II or in the Chl b-binding capacity of the apoproteins constituting LHC II. Photosynthesis was saturated at approximately 5 fg C(fg Chl)-’ h-’ or 6 fg C cell-’ h-’, and growth was saturated at approximately 0.45 d-’ for both MED and SARC strains at 18”C, but saturating irradiances differed between strains. Atlantic strains exhibited increased light-saturated rates and quantum yield for carbon fixation under blue light.
Frederic Partensky - One of the best experts on this subject based on the ideXlab platform.
-
independent evolution of the prochlorophyte and green plant chlorophyll a b light harvesting proteins
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: G W M Van Der Staay, Anthony W. D. Larkum, Roger G. Hiller, Susan S. Golden, Frederic Partensky, A Ducret, Ruedi Aebersold, R Li, Pamela M Wrench, Beverley R GreenAbstract:The prochlorophytes are oxygenic prokaryotes differing from other cyanobacteria by the presence of a light-harvesting system containing both chlorophylls (Chls) a and b and by the absence of phycobilins. We demonstrate here that the Chl a/b binding proteins from all three known prochlorophyte genera are closely related to IsiA, a cyanobacterial Chl a-binding protein induced by iron starvation, and to CP43, a constitutively expressed Chl a antenna protein of photosystem II. The prochlorophyte Chl a/b protein (pcb) genes do not belong to the extended gene family encoding eukaryotic Chl a/b and Chl a/c light-harvesting proteins. Although higher plants and prochlorophytes share common pigment complements, their light-harvesting systems have evolved independently.
-
coexistence of phycoerythrin and a chlorophyll a b antenna in a marine prokaryote
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Wolfgang R. Hess, G W M Van Der Staay, Frederic Partensky, Jose Manuel Garciafernandez, Thomas Borner, Daniel VaulotAbstract:Abstract 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 the alpha subunit designate it as a novel PE type, which we propose naming PE-III. P. marinus is the sole prokaryotic organisms known so far that contains chlorophylls a and b as well as phycobilins. These data strongly suggest that the common ancestor of prochlorophytes and the Synechococcus cyanobacteria contained phycobilins. Flow cytometric data from the tropical Pacific Ocean provide evidence that deep populations of Prochlorococcus possess low amounts of a PE-like pigment, which could serve either in light harvesting or nitrogen storage or both.
-
High degree of genetic variation in Prochlorococcus (Prochlorophyta) revealed by RFLP analysis
European Journal of Phycology, 1996Co-Authors: David J. Scanlan, Frederic Partensky, Wolfgang R. Hess, Julie Newman, Daniel VaulotAbstract:A genetic characterization of nine strains of Prochlorococcus originating from various depths of the Mediterranean Sea, the Sargasso Sea, the North and the tropical Atlantic Ocean and the Pacific Ocean was performed by restriction fragment length polymorphism (RFLP) mapping using probes for rbcL, rbcS, psbA and woxA. This study revealed extensive genetic variation among strains, which were grouped into two distinct clusters. Unexpectedly, with one exception (TATL1 strain), the strains clustered by isolation depth (i.e. near surface versus deep isolates) rather than by geographic origin. These relationships were confirmed by secondary RFLP analysis of psbA amplification products using Prochlorococcus-specific polymerase chain reaction (PCR) primers.
-
Characterization of the single psbA gene of Prochlorococcus marinus CCMP 1375 (Prochlorophyta)
Plant Molecular Biology, 1995Co-Authors: Wolfgang R. Hess, Frederic Partensky, Andreas Weihe, Susan Loiseaux-de Goër, Daniel VaulotAbstract: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. Phylogenetic trees suggested the D1-1 iso -form from Synechococcus PCC 7942 as the next related D1 protein and place P. Marinus separately from Prochlorothrix hollandica among the cyanobacteria.
-
Sequencing of RAPD fragments amplified from the genome of the prokaryote Prochlorococcus marinus (Prochlorophyta).
Biochemistry and molecular biology international, 1995Co-Authors: Lorenz M, Frederic Partensky, Thomas Borner, Wolfgang R. HessAbstract: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 high AT score of 63% and 71%, respectively. With the two (GATA)4 clones and the M13/300 clone strain-specific signals were obtained in a Southern blot analysis of various Prochlorococcus strains. Clones M13/1300 and OPB-10/1100, containing the ORFs, produced RFLPs between the strains analyzed. All RAPD fragments are represented as single copy in the genome of Prochlorococcus.
Peter J Lockhart - One of the best experts on this subject based on the ideXlab platform.
-
sequence of prochloron didemni atpbe and the inference of chioroplast origins endosymbiosis Prochlorophyta phylogeny atp synthase cyanobacteria
2016Co-Authors: Peter J Lockhart, T J Beanlandt, C J Howet, Anthony W. D. LarkumAbstract:The prochlorophytes, oxygenic photosyn- thetic prokaryotes containing chlorophylls a and b, have been put forward as descended from the organisms that gave rise to chloroplasts of green planis and algae by endosymbiosis, although this has always been controversial. To assess the phylogenetic position of the prochlorophyte Prochloron di- demni, we have cloned and sequenced its atpBE genes. Phylo- genetic inference under a range of models gives moderate to strong support for a cyanobacterial grouping rather than a chloroplast one. Possible systematic errors in this and previous analyses of prochlorophyte sequences are discussed. 1. ~~~~~2. 3.
-
IsProchlorothrix hollandica the best choice as a prokaryotic model for higher plant Chla/b photosynthesis?
Photosynthesis Research, 1993Co-Authors: Peter J Lockhart, David Penny, Michael D. Hendy, Anthony D. W. LarkumAbstract:We examine the issue of prochlorophyte origins and provide analyses which highlight the limitations of inferring evolutionary trees from anciently diverged sequences that have markedly different GC contents. Under these conditions we have found that current tree reconstruction methods strongly group together sequences with similar GC contents, whether or not the sequences share a common ancestor. We provide 3′ psbA termini sequence for Prochloron didemni and find it does not have the 7 amino acid deletion that occurs in Chl a/b chloroplasts and Prochlorothrix hollandica . This is consistent with the recent findings of a Chl c like pigment in the light harvesting system in other prochlorophytes but apparently absent in P. hollandica . From these observations we suggest that P. hollandica is the prochlorophyte most closely related to Chl a/b containing chloroplasts and hence the most appropriate prokaryotic model for higher plant Chl a/b photosynthesis.
-
sequence of prochloron didemni atpbe and the inference of chloroplast origins
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: Peter J Lockhart, Timothy J Beanland, Christopher J. Howe, Anthony W. D. LarkumAbstract:Abstract The prochlorophytes, oxygenic photosynthetic prokaryotes containing chlorophylls a and b, have been put forward as descended from the organisms that gave rise to chloroplasts of green plants and algae by endosymbiosis, although this has always been controversial. To assess the phylogenetic position of the prochlorophyte Prochloron didemni, we have cloned and sequenced its atpBE genes. Phylogenetic inference under a range of models gives moderate to strong support for a cyanobacterial grouping rather than a chloroplast one. Possible systematic errors in this and previous analyses of prochlorophyte sequences are discussed.