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Nathan J. Tublitz - One of the best experts on this subject based on the ideXlab platform.
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video analyses of Chromatophore activity in the european cuttlefish sepia officinalis
Journal of Experimental Marine Biology and Ecology, 2013Co-Authors: Eli Goodwin, Nathan J. TublitzAbstract:Abstract There is a paucity of quantitative methods to measure Chromatophore activity in cephalopods, without which, important questions regarding Chromatophore function cannot be addressed. These questions include the mechanisms underlying graduated responses by Chromatophores and the variations in responses by Chromatophore color type. We have developed an efficient and accurate method to record and analyze the activity of individual Chromatophores using a combination of video capture and computer analysis techniques. High performance video recordings were obtained from 20 to 40 Chromatophores isolated from the fin of the European cuttlefish, Sepia officinalis. Captured frames were imported into MATLAB for image segmentation analyses using polygon masking to identify individual Chromatophores. RGB thresholds were determined for each Chromatophore analyzed and were used to follow the activity of individual Chromatophores and to discriminate yellow and red-black Chromatophores. Data from tests using colored paper squares and live Chromatophores confirmed the utility of this novel procedure.
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Video analyses of Chromatophore activity in the European cuttlefish, Sepia officinalis ☆
Journal of Experimental Marine Biology and Ecology, 2013Co-Authors: Eli Goodwin, Nathan J. TublitzAbstract:Abstract There is a paucity of quantitative methods to measure Chromatophore activity in cephalopods, without which, important questions regarding Chromatophore function cannot be addressed. These questions include the mechanisms underlying graduated responses by Chromatophores and the variations in responses by Chromatophore color type. We have developed an efficient and accurate method to record and analyze the activity of individual Chromatophores using a combination of video capture and computer analysis techniques. High performance video recordings were obtained from 20 to 40 Chromatophores isolated from the fin of the European cuttlefish, Sepia officinalis. Captured frames were imported into MATLAB for image segmentation analyses using polygon masking to identify individual Chromatophores. RGB thresholds were determined for each Chromatophore analyzed and were used to follow the activity of individual Chromatophores and to discriminate yellow and red-black Chromatophores. Data from tests using colored paper squares and live Chromatophores confirmed the utility of this novel procedure.
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Principles underlying Chromatophore addition during maturation in the European cuttlefish, Sepia officinalis.
Journal of Experimental Biology, 2011Co-Authors: Jarred Yacob, Alexandra Cosima Lewis, Allyson Gosling, Debra H. J. St Hilaire, Lindsay Tesar, Michelle Mcrae, Nathan J. TublitzAbstract:SUMMARY The goal of this work was to identify some of the principles underlying Chromatophore growth and development in the European cuttlefish, Sepia officinalis . One set of experiments used a regeneration model to follow the re-growth of black Chromatophores for 30 days following excision of a small piece of fin tissue. A separate set of experiments tracked and analyzed the addition of new fin Chromatophores during a month of normal, undisturbed growth. We also followed the development of individual Chromatophores from their initial appearance to full maturation to determine whether their color type was fixed. Based on the results of these studies, we propose five guiding principles for Chromatophore growth and maturation. (1) The three Chromatophore cell types – black, reddish-brown and yellow – are present at different spatial frequencies in the cuttlefish fin. (2) During normal growth, new Chromatophores are inserted at a higher spatial frequency than existing (control) Chromatophores of the same color type. (3) In regenerating tissue, new black Chromatophores are initially added at low spatial frequencies. As regeneration continues, new black Chromatophores appear at increasing spatial frequencies until they are inserted at a spatial frequency higher than that observed in control tissue, similar to the way in which Chromatophores were observed to be added in normally growing tissue. (4) All Chromatophores first appear as pale orange cells and slowly darken into their respective color types without passing through intermediate color stages. (5) New black Chromatophores undergo a doubling in size as they mature, while reddish-brown and yellow Chromatophores do not grow at all after they are inserted in the dermis.
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central distribution and three dimensional arrangement of fin Chromatophore motoneurons in the cuttlefish sepia officinalis
Invertebrate Neuroscience, 2006Co-Authors: Michelle R Gaston, Nathan J. TublitzAbstract:Cephalopod body patterning is a most complex invertebrate behavior. Generated primarily by pigment-containing Chromatophore organs, this behavior enables rapid alteration of body coloration as a result of direct innervation of Chromatophores by motoneurons. This study focuses on location and arrangement of fin Chromatophore motoneurons in the cuttlefish Sepia and investigates the possibility of central topography. Retrograde labeling of topographically arranged fin nerve branches in the periphery revealed the posterior subesophageal mass (PSEM) of the brain as the primary location of fin Chromatophore motoneurons; within this region, most cells were located in the posterior Chromatophore and fin lobes. Additionally, a small percentage of labeled motoneurons occurred in the anterior subesophageal mass and the stellate ganglia. Data from three-dimensional reconstructions of PSEMs showed the arrangement of labeled motoneurons within individual lobes; these data suggest no obvious topographic arrangement. Further, electrical stimulation of the PSEM generated Chromatophore activity on the fin and mantle. These stimulation results, coupled with the retrograde labeling, suggest that Chromatophore motoneurons are located across multiple PSEM lobes.
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peripheral innervation patterns and central distribution of fin Chromatophore motoneurons in the cuttlefish sepia officinalis
The Journal of Experimental Biology, 2004Co-Authors: Michelle R Gaston, Nathan J. TublitzAbstract:Body patterning behavior in unshelled cephalopod molluscs such as squid, octopuses, and cuttlefish is the ability of these animals to create complex patterns on their skin. This behavior is generated primarily by Chromatophores, pigment-containing organs that are directly innervated by central motoneurons. The present study focuses on innervation patterns and location of Chromatophore motoneurons in the European cuttlefish Sepia officinalis, specifically those motoneurons that control Chromatophores of the fin. The fin is known to be innervated by the large, branching fin nerve. This study further characterizes the innervation of fin Chromatophores by the fin nerve, generates a reference system for the location of fin nerve branches across individuals, and localizes the neurons whose axons innervate fin Chromatophores through the fin nerve. Data from extracellular stimulation of fin nerve branches in intact animals demonstrate topographic innervation of fin Chromatophores, while retrograde labeling data reveal the posterior subesophageal mass of the brain as the primary location of fin Chromatophore motoneurons.
Hwan Su Yoon - One of the best experts on this subject based on the ideXlab platform.
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evolutionary dynamics of the Chromatophore genome in three photosynthetic paulinella species
Scientific Reports, 2019Co-Authors: Duckhyun Lhee, Sunju Kim, Debashish Bhattacharya, Myung Gil Park, Hwan Su YoonAbstract:The thecate amoeba Paulinella is a valuable model for understanding plastid organellogenesis because this lineage has independently gained plastids (termed Chromatophores) of alpha-cyanobacterial provenance. Plastid primary endosymbiosis in Paulinella occurred relatively recently (90–140 million years ago, Mya), whereas the origin of the canonical Archaeplastida plastid occurred >1,500 Mya. Therefore, these two events provide independent perspectives on plastid formation on vastly different timescales. Here we generated the complete Chromatophore genome sequence from P. longichromatophora (979,356 bp, GC-content = 38.8%, 915 predicted genes) and P. micropora NZ27 (977,190 bp, GC-content = 39.9%, 911 predicted genes) and compared these data to that from existing Chromatophore genomes. Our analysis suggests that when a basal split occurred among photosynthetic Paulinella species ca. 60 Mya, only 35% of the ancestral orthologous gene families from the cyanobacterial endosymbiont remained in Chromatophore DNA. Following major gene losses during the early stages of endosymbiosis, this process slowed down significantly, resulting in a conserved gene content across extant taxa. Chromatophore genes faced relaxed selection when compared to homologs in free-living alpha-cyanobacteria, likely reflecting the homogeneous intracellular environment of the Paulinella host. Comparison of nucleotide substitution and insertion/deletion events among different P. micropora strains demonstrates that increases in AT-content and genome reduction are ongoing and dynamic processes in Chromatophore evolution.
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diversity of the photosynthetic paulinella species with the description of paulinella micropora sp nov and the Chromatophore genome sequence for strain kr01
Protist, 2017Co-Authors: Duckhyun Lhee, Eun Chan Yang, Takuro Nakayama, Jong Im Kim, Giuseppe C Zuccarello, Robert A Andersen, Hwan Su YoonAbstract:The thecate filose amoeba Paulinella chromatophora is a good model organism for understanding plastid organellogenesis because its Chromatophore was newly derived from an alpha-cyanobacterium. Paulinella chromatophora was the only known photosynthetic Paulinella species until recent studies that suggested a species level of diversity. Here, we described a new photosynthetic species P. micropora sp. nov. based on morphological and molecular evidence from a newly established strain KR01. The Chromatophore genome of P. micropora KR01 was fully determined; the genome was 976,991bp in length, the GC content was 39.9%, and 908 genes were annotated. A pairwise comparison of Chromatophore genome sequences between strains KR01 and FK01, representing two different natural populations of P. micropora, showed a 99.85% similarity. Differences between the two strains included single nucleotide polymorphisms (SNPs) in CDSs, which resulted in 357 synonymous and 280 nonsynonymous changes, along with 245 SNPs in non-coding regions. Indels (37) and microinversions (14) were also detected. Species diversity for photosynthetic Paulinella was surveyed using samples collected from around the world. We compared our new species to two photosynthetic species, P. chromatophora and P. longichromatophora. Phylogenetic analyses using four gene markers revealed three distinct lineages of photosynthetic Paulinella species including P. micropora sp. nov.
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Photosynthetic Paulinella : Recapitulation of Primary Plastid Establishment
Endosymbiosis, 2013Co-Authors: Hwan Su Yoon, Eun Chan Yang, Debashish BhattacharyaAbstract:The origin of photosynthesis in eukaryotes stems from a single primary endosymbiosis between a heterotrophic protist cell and a cyanobacterium that occurred more than 1.5 billion years ago. This proto-algal population gave rise to three lineages of the Plantae (Rhodophyta, Viridiplantae, and Glaucophyta). Rhodoplasts and chloroplasts were later spread horizontally into other eukaryotic lineages through secondary endosymbiosis. Primary endosymbiosis is therefore a critical feature of eukaryotic evolution; however, it is difficult to study because of the long evolutionary time span that has passed since primary plastid origin. The filose amoeba Paulinella chromatophora is an exceptional species that contains two plastids, referred to as “Chromatophores,” that originated from a Synechococcus-like cyanobacterium. Photosynthetic Paulinella provides an ideal model to gain insights into the origin of photoautotrophy because its sister species are all heterotrophs that prey on cyanobacteria. Here, we review the evolutionary process that led to this second instance of primary endosymbiosis based on recent studies that include biodiversity surveys and plastid and nuclear genome data. Draft genome data from heterotrophic Paulinella using the single-cell genomics approach demonstrate two cases of horizontal gene transfer (HGT) from cyanobacteria, demonstrating that prey items are potential sources of foreign DNA in these taxa. Genome data from photosynthetic Paulinella provide evidence of massive gene loss from the Chromatophore genome, endosymbiotic gene transfer (EGT) to the host nucleus, and the potential establishment of a plastid protein import system that relies on the secretory pathway in the amoeba. We also present recent data regarding postendosymbiotic speciation in photosynthetic Paulinella and lineage specific differential gene loss and EGT.
Roger T. Hanlon - One of the best experts on this subject based on the ideXlab platform.
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The structure–function relationships of a natural nanoscale photonic device in cuttlefish Chromatophores
Journal of the Royal Society Interface, 2014Co-Authors: Leila F Deravi, Andrew P Magyar, Sean P Sheehy, George R R Bell, Stephen L. Senft, Alan M. Kuzirian, Lydia M. Mäthger, Trevor J. Wardill, William S Lane, Roger T. HanlonAbstract:Cuttlefish, Sepia officinalis, possess neurally controlled, pigmented Chromatophore organs that allow rapid changes in skin patterning and coloration in response to visual cues. This process of adaptive coloration is enabled by the 500% change in Chromatophore surface area during actuation. We report two adaptations that help to explain how colour intensity is maintained in a fully expanded Chromatophore when the pigment granules are distributed maximally: (i) pigment layers as thin as three granules that maintain optical effectiveness and (ii) the presence of high-refractive-index proteins—reflectin and crystallin—in granules. The latter discovery, combined with our finding that isolated Chromatophore pigment granules fluoresce between 650 and 720 nm, refutes the prevailing hypothesis that cephalopod Chromatophores are exclusively pigmentary organs composed solely of ommochromes. Perturbations to granular architecture alter optical properties, illustrating a role for nanostructure in the agile, optical responses of Chromatophores. Our results suggest that cephalopod Chromatophore pigment granules are more complex than homogeneous clusters of chromogenic pigments. They are luminescent protein nanostructures that facilitate the rapid and sophisticated changes exhibited in dermal pigmentation.
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malleable skin coloration in cephalopods selective reflectance transmission and absorbance of light by Chromatophores and iridophores
Cell and Tissue Research, 2007Co-Authors: Lydia M. Mäthger, Roger T. HanlonAbstract:Nature’s best-known example of colorful, changeable, and diverse skin patterning is found in cephalopods. Color and pattern changes in squid skin are mediated by the action of thousands of pigmented Chromatophore organs in combination with subjacent light-reflecting iridophore cells. Chromatophores (brown, red, yellow pigment) are innervated directly by the brain and can quickly expand and retract over underlying iridophore cells (red, orange, yellow, green, blue iridescence). Here, we present the first spectral account of the colors that are produced by the interaction between Chromatophores and iridophores in squid (Loligo pealeii). Using a spectrometer, we have acquired highly focused reflectance measurements of Chromatophores, iridophores, and the quality and quantity of light reflected when both interact. Results indicate that the light reflected from iridophores can be filtered by the Chromatophores, enhancing their appearance. We have also measured polarization aspects of iridophores and Chromatophores and show that, whereas structurally reflecting iridophores polarize light at certain angles, pigmentary Chromatophores do not. We have further measured the reflectance change that iridophores undergo during physiological activity, from “off” to various degrees of “on”, revealing specifically the way that colors shift from the longer end (infra-red and red) to the shorter (blue) end of the spectrum. By demonstrating that three color classes of pigments, combined with a single type of reflective cell, produce colors that envelop the whole of the visible spectrum, this study provides an insight into the optical mechanisms employed by the elaborate skin of cephalopods to give the extreme diversity that enables their dynamic camouflage and signaling.
Eva C M Nowack - One of the best experts on this subject based on the ideXlab platform.
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impact of light intensity and quality on Chromatophore and nuclear gene expression in paulinella chromatophora an amoeba with nascent photosynthetic organelles
Plant Journal, 2017Co-Authors: Ru Zhang, Debashish Bhattacharya, Eva C M Nowack, Dana C Price, Arthur R GrossmanAbstract:Summary Plastid evolution has been attributed to a single primary endosymbiotic event that occurred about 1.6 billion years ago (BYA) in which a cyanobacterium was engulfed and retained by a eukaryotic cell, although early steps in plastid integration are poorly understood. The photosynthetic amoeba Paulinella chromatophora represents a unique model for the study of plastid evolution because it contains cyanobacterium-derived photosynthetic organelles termed ‘Chromatophores’ that originated relatively recently (0.09–0.14 BYA). The Chromatophore genome is about a third the size of the genome of closely related cyanobacteria, but 10-fold larger than most plastid genomes. Several genes have been transferred from the Chromatophore genome to the host nuclear genome through endosymbiotic gene transfer (EGT). Some EGT-derived proteins could be imported into Chromatophores for function. Two photosynthesis-related genes (psaI and csos4A) are encoded by both the nuclear and Chromatophore genomes, suggesting that EGT in Paulinella chromatophora is ongoing. Many EGT-derived genes encode proteins that function in photosynthesis and photoprotection, including an expanded family of high-light-inducible (ncHLI) proteins. Cyanobacterial hli genes are high-light induced and required for cell viability under excess light. We examined the impact of light on Paulinella chromatophora and found that this organism is light sensitive and lacks light-induced transcriptional regulation of Chromatophore genes and most EGT-derived nuclear genes. However, several ncHLI genes have reestablished light-dependent regulation, which appears analogous to what is observed in cyanobacteria. We postulate that expansion of the ncHLI gene family and its regulation may reflect the light/oxidative stress experienced by Paulinella chromatophora as a consequence of the as yet incomplete integration of host and Chromatophore metabolisms.
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gene transfers from diverse bacteria compensate for reductive genome evolution in the Chromatophore of paulinella chromatophora
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Eva C M Nowack, Debashish Bhattacharya, Dana C Price, Michael Melkonian, Anna Singer, Arthur R GrossmanAbstract:Abstract Plastids, the photosynthetic organelles, originated >1 billion y ago via the endosymbiosis of a cyanobacterium. The resulting proliferation of primary producers fundamentally changed global ecology. Endosymbiotic gene transfer (EGT) from the intracellular cyanobacterium to the nucleus is widely recognized as a critical factor in the evolution of photosynthetic eukaryotes. The contribution of horizontal gene transfers (HGTs) from other bacteria to plastid establishment remains more controversial. A novel perspective on this issue is provided by the amoeba Paulinella chromatophora, which contains photosynthetic organelles (Chromatophores) that are only 60–200 million years old. Chromatophore genome reduction entailed the loss of many biosynthetic pathways including those for numerous amino acids and cofactors. How the host cell compensates for these losses remains unknown, because the presence of bacteria in all available P. chromatophora cultures excluded elucidation of the full metabolic capacity and occurrence of HGT in this species. Here we generated a high-quality transcriptome and draft genome assembly from the first bacteria-free P. chromatophora culture to deduce rules that govern organelle integration into cellular metabolism. Our analyses revealed that nuclear and Chromatophore gene inventories provide highly complementary functions. At least 229 nuclear genes were acquired via HGT from various bacteria, of which only 25% putatively arose through EGT from the Chromatophore genome. Many HGT-derived bacterial genes encode proteins that fill gaps in critical Chromatophore pathways/processes. Our results demonstrate a dominant role for HGT in compensating for organelle genome reduction and suggest that phagotrophy may be a major driver of HGT.
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Chromatophore Genome Sequence of Paulinella Sheds Light on Acquisition of Photosynthesis by Eukaryotes
Current biology : CB, 2008Co-Authors: Eva C M Nowack, Michael Melkonian, Gernot GlöcknerAbstract:Summary Background It is commonly accepted that a single primary endosymbiosis gave rise to the photosynthetic organelles of plants, the plastids. Recently, we presented evidence that photosynthetic inclusions, termed "Chromatophores," present in the filose thecamoeba Paulinella chromatophora originated from an independent, more recent primary endosymbiotic event. To clarify metabolic capabilities of the Chromatophore and its state of integration into the host, we present here the complete genome sequence of the Chromatophore. Results Our data reveal a fundamental reduction of the Chromatophore genome. The single, circular chromosome of 1.02 Mb encodes 867 protein-coding genes and is, therewith, the smallest cyanobacterial genome reported to date. Compared to Synechococcus WH5701, a free-living relative of the Chromatophore, only 26% of the genes were retained. Eleven putative pseudogenes were identified, indicating that reductive genome evolution is ongoing. Although the Chromatophore genome contains a complete set of photosynthesis genes, it lacks not only genes thought to be dispensable for an intracellular lifestyle but also genes of essential pathways for amino acid and cofactor synthesis. Conclusions Our data characterize the Chromatophore as a photosynthetic entity that is absolutely dependent on its host for growth and survival. Thus, the Chromatophores of P. chromatophora are the only known cyanobacterial descendants besides plastids with a significantly reduced genome that confer photosynthesis to their eukaryotic host. Their comparison with plastids and bacterial endosymbionts of invertebrates sheds light on early steps of the integration of a photosynthetic prokaryote into a eukaryotic cell.
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the ancestor of the paulinella Chromatophore obtained a carboxysomal operon by horizontal gene transfer from a nitrococcus like γ proteobacterium
BMC Evolutionary Biology, 2007Co-Authors: Birger Marin, Eva C M Nowack, Gernot Glöckner, Michael MelkonianAbstract:Paulinella chromatophora is a freshwater filose amoeba with photosynthetic endosymbionts (Chromatophores) of cyanobacterial origin that are closely related to free-living Prochlorococcus and Synechococcus species (PS-clade). Members of the PS-clade of cyanobacteria contain a proteobacterial form 1A RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) that was acquired by horizontal gene transfer (HGT) of a carboxysomal operon. In rDNA-phylogenies, the Paulinella Chromatophore diverged basal to the PS-clade, raising the question whether the HGT occurred before or after the split of the Chromatophore ancestor. Phylogenetic analyses of the almost complete rDNA operon with an improved taxon sampling containing most known cyanobacterial lineages recovered the Paulinella Chromatophore as sister to the complete PS-clade. The sequence of the complete carboxysomal operon of Paulinella was determined. Analysis of RubisCO large subunit (rbcL) sequences revealed that Paulinella shares the proteobacterial form 1A RubisCO with the PS-clade. The γ-proteobacterium Nitrococcus mobilis was identified as sister of the Paulinella Chromatophore and the PS-clade in the RubisCO phylogeny. Gene content and order in the carboxysomal operon correlates well with the RubisCO phylogeny demonstrating that the complete carboxysomal operon was acquired by the common ancestor of the Paulinella Chromatophore and the PS-clade through HGT. The carboxysomal operon shows a significantly elevated AT content in Paulinella, which in the rbcL gene is confined to third codon positions. Combined phylogenies using rbcL and the rDNA-operon resulted in a nearly fully resolved tree of the PS-clade. The HGT of the carboxysomal operon predated the divergence of the Chromatophore ancestor from the PS-clade. Following HGT and divergence of the Chromatophore ancestor, diversification of the PS-clade into at least three subclades occurred. The γ-proteobacterium Nitrococcus mobilis represents the closest known relative to the donor of the carboxysomal operon. The isolated position of the Paulinella Chromatophore in molecular phylogenies as well as its elevated AT content suggests that the Paulinella Chromatophore has already undergone typical steps in the reductive evolution of an endosymbiont.
Myung Gil Park - One of the best experts on this subject based on the ideXlab platform.
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evolutionary dynamics of the Chromatophore genome in three photosynthetic paulinella species
Scientific Reports, 2019Co-Authors: Duckhyun Lhee, Sunju Kim, Debashish Bhattacharya, Myung Gil Park, Hwan Su YoonAbstract:The thecate amoeba Paulinella is a valuable model for understanding plastid organellogenesis because this lineage has independently gained plastids (termed Chromatophores) of alpha-cyanobacterial provenance. Plastid primary endosymbiosis in Paulinella occurred relatively recently (90–140 million years ago, Mya), whereas the origin of the canonical Archaeplastida plastid occurred >1,500 Mya. Therefore, these two events provide independent perspectives on plastid formation on vastly different timescales. Here we generated the complete Chromatophore genome sequence from P. longichromatophora (979,356 bp, GC-content = 38.8%, 915 predicted genes) and P. micropora NZ27 (977,190 bp, GC-content = 39.9%, 911 predicted genes) and compared these data to that from existing Chromatophore genomes. Our analysis suggests that when a basal split occurred among photosynthetic Paulinella species ca. 60 Mya, only 35% of the ancestral orthologous gene families from the cyanobacterial endosymbiont remained in Chromatophore DNA. Following major gene losses during the early stages of endosymbiosis, this process slowed down significantly, resulting in a conserved gene content across extant taxa. Chromatophore genes faced relaxed selection when compared to homologs in free-living alpha-cyanobacteria, likely reflecting the homogeneous intracellular environment of the Paulinella host. Comparison of nucleotide substitution and insertion/deletion events among different P. micropora strains demonstrates that increases in AT-content and genome reduction are ongoing and dynamic processes in Chromatophore evolution.
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paulinella longichromatophora sp nov a new marine photosynthetic testate amoeba containing a Chromatophore
Protist, 2016Co-Authors: Sunju Kim, Myung Gil ParkAbstract:The freshwater testate filose amoeba Paulinella chromatophora is the sole species in the genus to have plastids, usually termed "Chromatophores", of a Synechococcus/Prochlorococcus-like cyanobacterial origin. Here, we report a new marine phototrophic species, Paulinella longichromatophora sp. nov., using light and electron microscopy and molecular data. This new species contains two blue-green U-shaped Chromatophores reaching up to 40 μm in total length. Further, the new Paulinella species is characterized by having five oral scales surrounding the pseudostomal aperture. All trees generated using three nuclear rDNA datasets (18S rDNA, 28S rDNA, and the concatenated 18S + 28S rDNA) demonstrated that three photosynthetic Paulinella species (two freshwater species, P. chromatophora and Paulinella strain FK01, and one marine species, P. longichromatophora) congruently formed a monophyletic group with strong support (≥ 90% of ML and ≥ 0.90 of PP), but their relationship to each other within the clade remained unresolved in all trees. P. longichromatophora, nevertheless, clustered consistently together with Paulinella strain FK01 with very low support, but the clade received strong support in plastid phylogenies. Phylogenetic analyses inferred from plastid-encoded 16S rDNA and a concatenated dataset of plastid 16S+23S rDNA demonstrated that Chromatophores of all photosynthetic Paulinella species were monophyletic. The monophyletic group fell within a cyanobacteria clade having a close relationship to an α-cyanobacterial clade containing Prochlorococcus and Synechococcus species with very robust support (100% of ML and 1.0 of PP). Additionally, phylogenetic analyses of nuclear 18S rDNA and plastid 16S rDNA suggested divergent evolution within the photosynthetic Paulinella population after a single acquisition of the Chromatophore. After the single acquisition of the Chromatophore, ancestral photosynthetic Paulinella appears to have diverged into at least two distinct clades, one containing the marine P. longichromatophora and freshwater Paulinella strain FK01, the other P. chromatophora CCAC 0185.