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Geoffrey I Mcfadden - One of the best experts on this subject based on the ideXlab platform.
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Cryptomonad evolution: Nuclear 18S rDNA phylogeny versus cell morphology and pigmentation
Journal of Phycology, 2002Co-Authors: James A Deane, Isabelle M. Strachan, Gary W. Saunders, David R. A. Hill, Geoffrey I McfaddenAbstract:A nuclearl8S rDNA phylogeny for cryptomonad algae is presented, including 11 species yet to be investigated by molecular means. The phylogenetic positions of the cryptomonad genera Campylomonas and Plagioselmis are assessed for the first time. Campylomonas groups most closely with morphologically similar species with the same accessory pigment from the genus Cryptomonas. Plagioselmis groups with the genera Teleaulax and Geminigera forming a clade whose members are united by unusual thylakoid arrangement. Nuclear 18S rDNA phylogeny divides cryptomonads into seven major lineages, two of which consist of the monospecific genera Proteomonas and Falcomonas. Analysis of nuclearl8S rDNA sequence supports suggestions that a Falcomonas-like cryptomonad gave rise to all other blue-green cryptomonads. New sequence from the plastid-lacking cryptomonad genus Goniomonas is also included, and the order of divergence of the major cryptomonad lineages is discussed. The morphology, number, and pigmentation of the cryptomonad plastidial complex are congruent with nuclear 18S rDNA phylogenies. Host cell features, such as periplast type, furrow/ gullet system, and cell shape, can be more variable and may be markedly different in species that are closely related by nuclear 18S rDNA phylogeny. Conversely, some species that are not closely related by molecular phylogeny may display a very similar, possibly primitive, periplast and furrow morphology.
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Evidence for nucleomorph to host nucleus gene transfer: light-harvesting complex proteins from cryptomonads and chlorarachniophytes.
Protist, 2000Co-Authors: James A Deane, Vanessa Su, Martin Fraunholz, Uwe G. Maier, Dion G. Durnford, William Martin, Geoffrey I McfaddenAbstract:Summary Cryptomonads and chlorarachniophytes acquired photosynthesis independently by engulfing and retaining eukaryotic algal cells. The nucleus of the engulfed cells (known as a nucleomorph) is much reduced and encodes only a handful of the numerous essential plastid proteins normally encoded by the nucleus of chloroplast-containing organisms. In cryptomonads and chlorarachniophytes these proteins are thought to be encoded by genes in the secondary host nucleus. Genes for these proteins were potentially transferred from the nucleomorph (symbiont nucleus) to the secondary host nucleus; nucleus to nucleus intracellular gene transfers. We isolated complementary DNA clones (cDNAs) for chlorophyll-binding proteins from a cryptomonad and a chlorarachniophyte. In each organism these genes reside in the secondary host nuclei, but phylogenetic evidence, and analysis of the targeting mechanisms, suggest the genes were initially in the respective nucleomorphs (symbiont nuclei). Implications for origins of secondary endosymbiotic algae are discussed.
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The secondary endosymbiont of the cryptomonad Guillardia theta contains alpha-, beta-, and gamma-tubulin genes.
Molecular biology and evolution, 1999Co-Authors: Patrick J. Keeling, Uwe G. Maier, James A Deane, Susan Douglas, Clara Hink-schauer, Geoffrey I McfaddenAbstract:Cryptomonads have acquired photosynthesis through secondary endosymbiosis: they have engulfed and retained a photosynthetic eukaryote. The remnants of this autotrophic symbiont are severely reduced, but a small volume of cytoplasm surrounding the plastid persists, along with a residual nucleus (the nucleomorph) that encodes only a few hundred genes. We characterized tubulin genes from the cryptomonad Guillardia theta. Despite the apparent absence of microtubules in the endosymbiont, we recovered genes encoding alpha-, beta-, and gamma-tubulins from the nucleomorph genome of G. theta. The presence of tubulin genes in the nucleomorph indicates that some component of the cytoskeleton is still present in the cryptomonad symbiont despite the fact that very little cytoplasm remains, no mitosis is known in the nucleomorph, and microtubules have never been observed anywhere in the symbiont. Phylogenetic analyses with nucleomorph alpha- and beta-tubulins support the origin of the cryptomonad nucleomorph from a red alga. We also characterized alpha and beta-tubulins from the host nucleus of G. theta and compared these with tubulins we isolated from two flagellates, Goniomonas truncata and Cyanophora paradoxa, previously proposed to be related to the cryptomonad host. Phylogenetic analyses support a relationship between the cryptomonad host and Goniomonas but do not support any relationship between cryptomonads and Cyanophora.
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Hanusia phi gen. et sp. nov. (Cryptophyceae): characterization of ‘Cryptomonas sp. Φ’
European Journal of Phycology, 1998Co-Authors: James A Deane, David R. A. Hill, Steven J. Brett, Geoffrey I McfaddenAbstract:Cryptomonas sp. Φ is an undescribed cryptomonad used for many studies into the endosymbiotic origin of plastids. Cryptomonas sp. Φ was characterized using electron microscopy, DNA sequencing and karyotyping. DNA sequence data show that Cryptomonas sp. Φ has been confused with the related cryptomonad, Guillardia theta, which is the organism actually used in most published studies on cryptomonad endosymbiosis to date. It is proposed that the strain Cryptomonas sp. Φ be recognized as a distinct species under the name Hanusia phi. Although Hanusia phi shares molecular and karyotypic features with G. theta, it cannot be assigned to Guillardia because it does not fit the morphological description of this genus. H. phi differs from G. theta in periplast structure, configuration of the furrowgullet system, and cell size. Morphologically, however, H. phi is very similar to Teleaulax acuta, Teleaulax merimbula and the diplomorph of Proteomonas sulcata.
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Cryptomonad nuclear and nucleomorph 18S rRNA phylogeny
European Journal of Phycology, 1996Co-Authors: J. A. Couch, Paul R. Gilson, James A Deane, David R. A. Hill, K. E. Thorsteinsen, Geoffrey I McfaddenAbstract:Nuclear and nucleomorph 18S ribosomal RNA genes from six cryptomonads were amplified by the polymerase chain reaction and sequenced. Phylogenetic trees were constructed by distance, parsimony, and maximum likelihood methods for all available cryptomonad nuclear and nucleomorph 18S rRNA sequences. Nuclear and nucleomorph trees are largely congruent and clearly disprove the idea of polyphyletic origins for cryptomonad chloroplasts. Both show the leucoplast-containing Chilomonas as the sister to all photosynthetic cryptomonads. Using 11 cryptomonad nucleomorph sequences gives more convincing evidence than before that cryptomonad nucleomorphs originated from a red alga and are not specifically related to Chlorarachnion nucleomorphs. Both trees show as a clade the genera with nucleomorphs embedded in a chloroplast-envelope invagination into the pyrenoid (Storeatula, Rhinomonas, Rhodomonas). This monophyly of embedded nucleomorphs supports the recent creation of the order Pyrenomonadales for such cryptomonads. ...
John M Archibald - One of the best experts on this subject based on the ideXlab platform.
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Retrotransposons and Tandem Repeat Sequences in the Nuclear Genomes of Cryptomonad Algae
2015Co-Authors: Sharen Bowman, John M ArchibaldAbstract:Abstract. The cryptomonads are an enigmatic group of unicellular eukaryotic algae that possess two nuclear genomes, having acquired photosynthesis by the uptake and retention of a eukaryotic algal endo-symbiont. The endosymbiont nuclear genome, or nucleomorph, of the cryptomonad Guillardia theta has been completely sequenced: at only 551 kilobases (kb) and with a gene density of 1 gene/kb, it is a model of compaction. In contrast, very little is known about the structure and composition of the crypto-monad host nuclear genome. Here we present the results of two small-scale sequencing surveys of fo-smid clone libraries from two distantly related cryp-tomonads, Rhodomonas salina CCMP1319 and Cryptomonas paramecium CCAP977/2A, corre
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Ultrastructure and molecular phylogeny of the cryptomonad Goniomonas avonlea sp. nov.
Protist, 2012Co-Authors: Eunsoo Kim, John M ArchibaldAbstract:We describe a new species of cryptomonad, Goniomonas avonlea sp. nov., using molecular phylogeny and comprehensive microscopic investigation. G. avonlea is a marine bacterivorous flagellate, measuring 8-11 μm long and 6-7 μm wide, with two subequal flagella that are directed anteriorly and posteriorly. G. avonlea is morphologically and genetically distinct from three other Goniomonas species that have been described to date. SEM and TEM show that G. avonlea shares ultrastructural features with other Goniomonas and cryptomonads, including the presence of bipartite ejectisomes, double septa in the transition region, flat mitochondrial cristae, a furrow complex, a rhizostyle, rectangular periplast plates, and the infundibulum. The discharged large ejectisome is straight and has a unique loose, reticulate layer. The flagellar apparatus includes non-tubular roots, microtubular roots, and a compound root that is reminiscent of the multilayered structure (MLS) observed in the flagellate cells of streptophytes and a few other eukaryotes. Molecular phylogenies based on 18S and 28S rRNA genes suggest a specific affiliation of G. avonlea to marine Goniomonas species, and support the monophyly of Goniomonas to the exclusion of plastid-bearing cryptomonads. Our study adds to a growing body of evidence for the high level of diversity and antiquity of the genus Goniomonas.
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complete nucleomorph genome sequence of the nonphotosynthetic alga Cryptomonas paramecium reveals a core nucleomorph gene set
Genome Biology and Evolution, 2011Co-Authors: Goro Tanifuji, Naoko T Onodera, Natalie Donaher, Travis J Wheeler, Marlena Dlutek, John M ArchibaldAbstract:Nucleomorphs are the remnant nuclei of algal endosymbionts that were engulfed by nonphotosynthetic host eukaryotes. These peculiar organelles are found in cryptomonad and chlorarachniophyte algae, where they evolved from red and green algal endosymbionts, respectively. Despite their independent origins, cryptomonad and chlorarachniophyte nucleomorph genomes are similar in size and structure: they are both <1 million base pairs in size (the smallest nuclear genomes known), comprised three chromosomes, and possess subtelomeric ribosomal DNA operons. Here, we report the complete sequence of one of the smallest cryptomonad nucleomorph genomes known, that of the secondarily nonphotosynthetic cryptomonad Cryptomonas paramecium. The genome is 486 kbp in size and contains 518 predicted genes, 466 of which are protein coding. Although C. paramecium lacks photosynthetic ability, its nucleomorph genome still encodes 18 plastid-associated proteins. More than 90% of the “conserved” protein genes in C. paramecium (i.e., those with clear homologs in other eukaryotes) are also present in the nucleomorph genomes of the cryptomonads Guillardia theta and Hemiselmis andersenii. In contrast, 143 of 466 predicted C. paramecium proteins (30.7%) showed no obvious similarity to proteins encoded in any other genome, including G. theta and H. andersenii. Significantly, however, many of these “nucleomorph ORFans” are conserved in position and size between the three genomes, suggesting that they are in fact homologous to one another. Finally, our analyses reveal an unexpected degree of overlap in the genes present in the independently evolved chlorarachniophyte and cryptomonad nucleomorph genomes: ∼80% of a set of 120 conserved nucleomorph genes in the chlorarachniophyte Bigelowiella natans were also present in all three cryptomonad nucleomorph genomes. This result suggests that similar reductive processes have taken place in unrelated lineages of nucleomorph-containing algae.
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Actin Gene Family Dynamics in Cryptomonads and Red Algae
Journal of Molecular Evolution, 2010Co-Authors: Goro Tanifuji, John M ArchibaldAbstract:Here we present evidence for a complex evolutionary history of actin genes in red algae and cryptomonads, a group that acquired photosynthesis secondarily through the engulfment of a red algal endosymbiont. Four actin genes were found in the nuclear genome of the cryptomonad, Guillardia theta , and in the genome of the red alga, Galdieria sulphuraria , a member of the Cyanidiophytina. Phylogenetic analyses reveal that the both organisms possess two distinct sequence types, designated “type-1” and “type-2.” A weak but consistent phylogenetic affinity between the cryptomonad type-2 sequences and the type-2 sequences of G. sulphuraria and red algae belonging to the Rhodophytina was observed. This is consistent with the possibility that the cryptomonad type-2 sequences are derived from the red algal endosymbiont that gave rise to the cryptomonad nucleomorph and plastid. Red algae as a whole possess two very different actin sequence types, with G. sulphuraria being the only organism thus far known to possess both. The common ancestor of Rhodophytina and Cyanidiophytina may have had two actin genes, with differential loss explaining the distribution of these genes in modern-day groups. Our study provides new insight into the evolution and divergence of actin genes in cryptomonads and red algae, and in doing so underscores the challenges associated with heterogeneity in actin sequence evolution and ortholog/paralog detection.
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the complete plastid genome sequence of the secondarily nonphotosynthetic alga Cryptomonas paramecium reduction compaction and accelerated evolutionary rate
Genome Biology and Evolution, 2009Co-Authors: Natalie Donaher, Naoko T Onodera, Goro Tanifuji, Stephanie Malfatti, Patrick S G Chain, Yoshiaki Hara, John M ArchibaldAbstract:The cryptomonads are a group of unicellular algae that acquired photosynthesis through the engulfment of a red algal cell, a process called secondary endosymbiosis. Here, we present the complete plastid genome sequence of the secondarily nonphotosynthetic species Cryptomonas paramecium CCAP977/2a. The approximately 78 kilobase pair (Kbp) C. paramecium genome contains 82 predicted protein genes, 29 transfer RNA genes, and a single pseudogene (atpF). The C. paramecium plastid genome is approximately 50 Kbp smaller than those of the photosynthetic cryptomonads Guillardia theta and Rhodomonas salina; 71 genes present in the G. theta and/or R. salina plastid genomes are missing in C. paramecium. The pet, psa, and psb photosynthetic gene families are almost entirely absent. Interestingly, the ribosomal RNA operon, present as inverted repeats in most plastid genomes (including G. theta and R. salina), exists as a single copy in C. paramecium. The G + C content (38%) is higher in C. paramecium than in other cryptomonad plastid genomes, and C. paramecium plastid genes are characterized by significantly different codon usage patterns and increased evolutionary rates. The content and structure of the C. paramecium plastid genome provides insight into the changes associated with recent loss of photosynthesis in a predominantly photosynthetic group of algae and reveals features shared with the plastid genomes of other secondarily nonphotosynthetic eukaryotes.
Susan E. Douglas - One of the best experts on this subject based on the ideXlab platform.
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The large ribosomal protein gene cluster of a cryptomonad plastid: Gene organization, sequence and evolutionary implications
Iubmb Life, 1997Co-Authors: Sheng‐long Wang, Susan E. DouglasAbstract:The complete sequence of the major ribosomal protein gene cluster of the plastid genome of the cryptomonad alga Guillardia theta (formerly Cryptomonas Φ) is presented. The ribosomal protein genes (corresponding to the SIO, spc, alpha and L13/S9 operons of E. coli are found upstream of the previously reported plastid str operon, and transcribed in the same orientation. The genes are very tightly packed with as little as two nucleotides between the rpll4 and rpl24 genes. The gene arrangement is very similar to that reported for the rhodophyte alga, Porphyra purpurea, and the chromophyte diatom, Odontella sinensis, indicating a close evolutionary relationship between these groups of algae. Northern analysis indicates that the 29 genes1 are arranged as one operon and are transcribed as a single mRNA that is subsequently processed into smaller transcripts.
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The large ribosomal protein gene cluster of a cryptomonad plastid: Gene organization, sequence and evolutionary implications
Iubmb Life, 1997Co-Authors: Sheng‐long Wang, Susan E. DouglasAbstract:The complete sequence of the major ribosomal protein gene cluster of the plastid genome of the cryptomonad alga Guillardia theta (formerly Cryptomonas Φ) is presented. The ribosomal protein genes (corresponding to the SIO, spc, alpha and L13/S9 operons of E. coli are found upstream of the previously reported plastid str operon, and transcribed in the same orientation. The genes are very tightly packed with as little as two nucleotides between the rpll4 and rpl24 genes. The gene arrangement is very similar to that reported for the rhodophyte alga, Porphyra purpurea, and the chromophyte diatom, Odontella sinensis, indicating a close evolutionary relationship between these groups of algae. Northern analysis indicates that the 29 genes1 are arranged as one operon and are transcribed as a single mRNA that is subsequently processed into smaller transcripts.
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Cryptomonad algae are evolutionary chimaeras of two phylogenetically distinct unicellular eukaryotes.
Nature, 1991Co-Authors: Susan E. Douglas, Colleen A. Murphy, David F. Spencer, Michael W. GrayAbstract:ALTHOUGH it is widely accepted that the plastids of plants and algae originated as endosymbionts1, the details of this evolutionary process are unclear2'3. It has been proposed that in organisms whose plastids are surrounded by more than two membranes, the endosymbiont was a eukaryotic alga rather than a photosynthetic prokaryote4. The DNA-containing5 nucleomorph6 of cryptomonad algae appears to be the vestigial nucleus of such an algal endosymbiont7. Eukaryotic-type ribosomal RNA sequences have been localized to a nucleolus-like structure in the nucleomorph8. In support of the hypothesis that cryptomonads are evolutionary chimaeras of two distinct eukaryotic cells, we show here that Cryptomonas Φ contains two phylogenetically separate, nuclear-type small-subunit rRNA genes, both of which are transcriptionally active. We incorporate our rRNA sequence data into phylogenetic trees, from which we infer the evolutionary ancestry of the host and symbiont components of Cryptomonas Φ. Such trees do not support the thesis3 that chromophyte algae evolved directly from a cryp-tomonad-like ancestor.
Richard Wetherbee - One of the best experts on this subject based on the ideXlab platform.
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Periplast development in Cryptophyceae III. Development of crystalline surface plates inFalcomonas daucoides, Proteomonas sulcata [haplomorph], andKomma caudata
Protoplasma, 1996Co-Authors: S. J. Brett, Richard WetherbeeAbstract:In several cryptomonad genera the surface periplast component (SPC) is composed of discrete crystalline plates surrounded by structurally distinct borders. Freeze-etch images enable detailed investigation of surface microarchitecture in these cryptomonads, and reveal that the plates consist of precisely aligned arrays of minute subunits. The plate borders are composed of similar subunits which display marked variations in alignment. Differences in the arrangement of subunits within the plates and borders appear closely linked to the organization of the underlying plasma membrane (PM) and inner periplast component (IPC). Development of the crystalline surface plates occurs within specialized anamorphic zones located along the mid-ventral line and around the vestibular margins of cells. Examination of variations in surface microarchitecture within anamorphic zones suggests that the crystalline plates form directly on the cell surface. Development of the surface plates results from the accumulation and self-assembly of subunits, while orderly addition of subunits to plate edges facilitates subsequent growth and enlargement. The close structural relationship between the SPC, PM, and IPC in these cryptomonads suggests that self-assembly of the surface plates may be mediated by developmental changes in the underlying PM and IPC.
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Periplast development in Cryptophyceae II. Development of the inner periplast component inRhinomonas pauca, Proteomonas sulcata [haplomorph],Rhodomonas baltica, andCryptomonas ovata
Protoplasma, 1996Co-Authors: S. J. Brett, Richard WetherbeeAbstract:The inner periplast component (IPC) of numerous cryptomonads is composed of discrete inner plates, situated beneath (and intimately associated with) the plasma membrane (PM). Freeze-fracture images reveal that the PM is organized into a series of ordered structural domains, which directly correspond in size and shape to the underlying inner plates. Freeze-fracture images are used here to compare IPC arrangement in Rhinomonas pauca, Proteomonas sulcata [haplomorph], Rhodomonas baltica , and Cryptomonas ovata , and to examine development of inner plates in these cryptomonads. In all genera examined, the IPC is highly ordered across most of the cell periphery but appears to be modified adjacent to the vestibulum and mid-ventral line, which represent the anamorphic zones. Variations in the size and shape of PM domains in these regions suggest that development of the IPC occurs within anamorphic zones, by the de novo formation and enlargement of inner plates throughout the cell cycle.
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Structure and development of the cryptomonad periplast: a review
The Protistan Cell Surface, 1994Co-Authors: S. J. Brett, L. Perasso, Richard WetherbeeAbstract:The structure and development of the complex periplast, or cell covering, of cryptomonads is reviewed. The periplast consists of the plasma membrane (PM) plus an associated surface periplast component (SPC) and cytoplasmic or inner periplast component (IPC). The structure of the SPC and IPC, and their association with the PM, varies considerably between genera. This review, which concentrates on cryptomonads with an IPC of discrete plates, discusses relationships between periplast components and examines the development of this unique cell covering. Formation and growth of inner plates occurs throughout the cell cycle from specialized regions termed anamorphic zones. Crystalline surface plates, which comprise the SPC in many cryptomonad species, appear to form by self-assembly of disorganized subunits. In Komma caudata the subunits are composed of a high molecular weight glycoprotein that is produced within the endomembrane system and deposited onto the cell surface within anamorphic zones. The self-assembly of subunits into highly ordered surface plates appears closely associated with developmental changes in the underlying IPC and PM.
David R. A. Hill - One of the best experts on this subject based on the ideXlab platform.
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Cryptomonad evolution: Nuclear 18S rDNA phylogeny versus cell morphology and pigmentation
Journal of Phycology, 2002Co-Authors: James A Deane, Isabelle M. Strachan, Gary W. Saunders, David R. A. Hill, Geoffrey I McfaddenAbstract:A nuclearl8S rDNA phylogeny for cryptomonad algae is presented, including 11 species yet to be investigated by molecular means. The phylogenetic positions of the cryptomonad genera Campylomonas and Plagioselmis are assessed for the first time. Campylomonas groups most closely with morphologically similar species with the same accessory pigment from the genus Cryptomonas. Plagioselmis groups with the genera Teleaulax and Geminigera forming a clade whose members are united by unusual thylakoid arrangement. Nuclear 18S rDNA phylogeny divides cryptomonads into seven major lineages, two of which consist of the monospecific genera Proteomonas and Falcomonas. Analysis of nuclearl8S rDNA sequence supports suggestions that a Falcomonas-like cryptomonad gave rise to all other blue-green cryptomonads. New sequence from the plastid-lacking cryptomonad genus Goniomonas is also included, and the order of divergence of the major cryptomonad lineages is discussed. The morphology, number, and pigmentation of the cryptomonad plastidial complex are congruent with nuclear 18S rDNA phylogenies. Host cell features, such as periplast type, furrow/ gullet system, and cell shape, can be more variable and may be markedly different in species that are closely related by nuclear 18S rDNA phylogeny. Conversely, some species that are not closely related by molecular phylogeny may display a very similar, possibly primitive, periplast and furrow morphology.
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Hanusia phi gen. et sp. nov. (Cryptophyceae): characterization of ‘Cryptomonas sp. Φ’
European Journal of Phycology, 1998Co-Authors: James A Deane, David R. A. Hill, Steven J. Brett, Geoffrey I McfaddenAbstract:Cryptomonas sp. Φ is an undescribed cryptomonad used for many studies into the endosymbiotic origin of plastids. Cryptomonas sp. Φ was characterized using electron microscopy, DNA sequencing and karyotyping. DNA sequence data show that Cryptomonas sp. Φ has been confused with the related cryptomonad, Guillardia theta, which is the organism actually used in most published studies on cryptomonad endosymbiosis to date. It is proposed that the strain Cryptomonas sp. Φ be recognized as a distinct species under the name Hanusia phi. Although Hanusia phi shares molecular and karyotypic features with G. theta, it cannot be assigned to Guillardia because it does not fit the morphological description of this genus. H. phi differs from G. theta in periplast structure, configuration of the furrowgullet system, and cell size. Morphologically, however, H. phi is very similar to Teleaulax acuta, Teleaulax merimbula and the diplomorph of Proteomonas sulcata.
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Cryptomonad nuclear and nucleomorph 18S rRNA phylogeny
European Journal of Phycology, 1996Co-Authors: J. A. Couch, Paul R. Gilson, James A Deane, David R. A. Hill, K. E. Thorsteinsen, Geoffrey I McfaddenAbstract:Nuclear and nucleomorph 18S ribosomal RNA genes from six cryptomonads were amplified by the polymerase chain reaction and sequenced. Phylogenetic trees were constructed by distance, parsimony, and maximum likelihood methods for all available cryptomonad nuclear and nucleomorph 18S rRNA sequences. Nuclear and nucleomorph trees are largely congruent and clearly disprove the idea of polyphyletic origins for cryptomonad chloroplasts. Both show the leucoplast-containing Chilomonas as the sister to all photosynthetic cryptomonads. Using 11 cryptomonad nucleomorph sequences gives more convincing evidence than before that cryptomonad nucleomorphs originated from a red alga and are not specifically related to Chlorarachnion nucleomorphs. Both trees show as a clade the genera with nucleomorphs embedded in a chloroplast-envelope invagination into the pyrenoid (Storeatula, Rhinomonas, Rhodomonas). This monophyly of embedded nucleomorphs supports the recent creation of the order Pyrenomonadales for such cryptomonads. ...
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Goniomonas : rRNA sequences indicate that this phagotrophic flagellate is a close relative of the host component of cryptomonads
European Journal of Phycology, 1994Co-Authors: Geoffrey I Mcfadden, Paul R. Gilson, David R. A. HillAbstract:The nucleotide sequence of the polymerase chain reaction (PCR)-amplified small subunit ribosomal RNA gene of Goniomonas truncata was determined. Addition of the Goniomonas sequence to the eukaryotic phylogenetic tree revealed this heterotrophic flagellate to be the sister taxon of photosynthetic cryptomonads. The molecular phylogeny supports morphological data suggesting that Goniomonas diverted from the cryptomonad lineage prior to their acquisition of a plastid through endosymbiosis of a eukaryote. Goniomonas, which is phagotrophic, may thus represent an extant relative of the host component of cryptomonad algae.
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A revised circumscription of Cryptomonas (Cryptophyceae) based on examination of Australian strains
Phycologia, 1991Co-Authors: David R. A. HillAbstract:Abstract Certain species of the genus Cryptomonas (Cryptophyceae) are re-examined, based on material collected in Australia. Details of the structure of the lectotype species, Cryptomonas ovata Ehrenberg, are reviewed, and the genus is redefined accordingly. Five other selected species that have previously been assigned to Cryptomonas are examined, one freshwater and four marine, and it is found that none of these can be referred to Cryptomonas in its revised state. Consequently, four new genera are proposed (Campylomonas gen. nov., Teleaulax gen. nov., Storeatula gen. nov. and Geminigera gen. nov.); the transfer of Cryptomonasstigmatica Wislouchto Rhodomonas is also proposed. The present, more restricted circumscription of Cryptomonas is discussed, and it is suggested that the large number of species currently assigned to the genus should be reduced considerably.