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Topic: Chlorarachniophyte

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	Chlorarachniophyte - Wikipedia, the free encyclopedia
		Chlorarachniophytes are a small group of algae occasionally found in tropical oceans.
		The only other group of algae that contain nucleomorphs are the cryptomonads, but their chloroplasts seem to be derived from a red alga.
		The chlorarachniophytes only include five genera, which show some variation in their life-cycles and may lack one or two of the stages described above.
	en.wikipedia.org /wiki/Chlorarachniophyte (247 words)

	Chlorarachniophytes
		Chlorarachniophytes are, therefore, a key group for understanding how chloroplasts have spread to many different groups of eukaryotes.
		Among the chlorarachniophytes, there is a remarkable diversity in ultrastructure of the pyrenoid and localization of the nucleomorph.
		This organelle is the vestigial nucleus of the eukaryotic algal endosymbiont that gave rise to the chloroplasts of chlorarachniophytes (McFadden et al.
	tolweb.org /tree?group=Chlorarachniophytes&contgroup=The_Other_Protists (2259 words)

	BioMed Central \| Full text \| Comparative rates of evolution in endosymbiotic nuclear genomes
		The nucleomorphs associated with secondary plastids of cryptomonads and chlorarachniophytes are the sole examples of organelles with eukaryotic nuclear genomes.
		The exceptions are the cryptomonads and chlorarachniophytes, which contain nucleomorphs, the remnant nuclei of the plastid-containing algae that were engulfed in the secondary endosymbioses that gave rise to these lineages (Figure 1).
		In chlorarachniophytes, however, the nucleomorph-encoded plastid-targeted proteins are evolving much faster than those encoded in the nucleus (as was also seen for non-plastid nucleomorph-encoded proteins), which provides one of the first indications that the mode of evolution in these two genomes is fundamentally different.
	www.biomedcentral.com /1471-2148/6/46 (6097 words)

	Genome Biology \| Full text \| Nucleomorph genomes: much ado about practically nothing
		Projects to sequence the nucleomorph genomes of cryptomonads and chlorarachniophytes therefore began several years ago [8], and the cryptomonad nucleomorph genome sequence was recently completed [1].
		Chlorarachniophyte nucleomorph genes have a surfeit of pygmy-sized introns, ranging from 18 to 20 nucleotides in length, with 19 being the most common [19].
		Chlorarachniophyte intron density, at 3.3 per kilobase of coding sequence, is only slightly less than average for eukaryotes (3.7 introns per kilobase) [21].
	genomebiology.com /2001/2/8/reviews/1022 (2989 words)

	Chlorarachniophytes
		Although they are an obscure and little known group of algae, chlorarachniophytes have been a magnet for evolutionary biologists interested in the origin and the evolution of chloroplasts.
		Both chlorarachniophytes and cryptomonads have nucleomorphs, the reduced nuclei of the algal endosymbiont that gave rise to the chloroplasts (Ludwig and Gibbs 1989, McFadden et al.
		Cavalier-Smith (1999) proposed the cabozoan theory which states that the chlorarachniophytes and the euglenophytes share a common photosynthetic ancestor that acquired its chloroplast by a secondary endosymbiosis from a green alga.
	tolweb.org /tree?group=Chlorarachniophytes&contgroup=The_Other_Protists (2259 words)

	Mergers and Acquisitions - - science news articles online technology magazine articles Mergers and Acquisitions (Site not responding. Last check: 2007-10-30)
		Lodged snugly between the second and third membranes of the choroplast is a structure that is called a nucleomorph because it resembles a cell nucleus.
		Chlorarachniophytes are not the only organisms with that problem, because they are far from the only algae that stole their chloroplasts from other eukaryotes.
		It was the initial enslavement of a bacterium as a chloroplast that created algae; and a huge new supply of algae may have been the food that helped fuel the explosive diversification of marine animals around 600 million years ago, at the beginning of the Cambrian Period.
	www.discover.com /issues/dec-94/departments/mergersandacquis464 (1451 words)

	Plastid - Biocrawler (Site not responding. Last check: 2007-10-30)
		Algae with complex plastids derived from a secondary endosymbiosis event with a red alga are the heterokonts, haptophytes, cryptomonads, and most dinoflagellates (= rhodoplasts).
		Those with endosymbioses with green algae are the euglenids and the chlorarachniophytes (= chloroplasts).
		The Apicomplexa (a phylum of obligate parasitic protozoans, which includes Plasmodium spp., causing malaria; Toxoplasma gondii, causing toxoplasmosis; Cryptosporidium parvum, causing cryptosporidiosis; Neospora spp.; and Eimeria spp.) also have complex plastids, which stopped photosynthesis and turned into leucoplasts.
	www.biocrawler.com /encyclopedia/Plastid (460 words)

	Chlorarachniophyte
		The chlorarachniophytes only include four genera: Chlorarachnion, Gymnochlora, Lotharella, and Cryptochlora.
		These show some variation in their life-cycles and may lack one or two of the stages described above.
		The euglenids have also been considered possible relatives, but this is based entirely on the presence of secondary green chloroplasts and is contradicted by structural and genetic studies.
	www.ebroadcast.com.au /lookup/encyclopedia/ch/Chlorarachniophyte.html (253 words)

	www.arareko.net: Comparative rates of evolution in endosymbiotic nuclear genomes
		We compared the evolutionary rates of genes from nuclear, nucleomorph, and plastid genomes, all of which encode proteins that function in the same cellular compartment, the plastid, and are thus subject to similar selection pressures.
		Chlorarachniophyte nucleomorph genes have accumulated errors at a faster rate than other genomes within the same cell, regardless of the compartment where the gene product functions.
		In contrast, most nucleomorph genes in cryptomonads have evolved faster than genes in other genomes on average, but genes for plastid-targeted proteins are not overly divergent, and it appears that cryptomonad nucleomorphs are not presently evolving rapidly and have therefore stabilized.
	www.arareko.net /blog/2006/06/comparative-rates-of-evolution-in.html (305 words)

	Plastid - Wikipedia, the free encyclopedia
		Algae with complex plastids derived by secondary endosymbiosis of a red alga include the heterokonts, haptophytes, cryptomonads, and most dinoflagellates (= rhodoplasts).
		Those that endosymbiosed a green alga include the euglenids and chlorarachniophytes (= chloroplasts).
		The Apicomplexa, a phylum of obligate parasitic protozoa including the causative agents of malaria (Plasmodium spp.), toxoplasmosis (Toxoplasma gondii), and many other human or animal diseases also harbor a complex plastid (although this organelle has been lost in some apicomplexans, such as Cryptosporidium parvum, which causes cryptosporidiosis).
	en.wikipedia.org /wiki/Plastid (993 words)

	Figure 1
		Diagrams of cryptomonad and chlorarachniophyte cells and their nucleomorph (Nm) genomes.
		Cryptomonad and chlorarachniophyte cells (left) contain red and green algal endosymbionts, respectively, the reduced nuclei (nucleomorphs) of which encode three repeat-capped chromosomes (right).
		In chlorarachniophytes, carbohydrate storage has moved from a chloroplast starch-based system to one based on β1,3 glucan within the host cell.
	genomebiology.com /2001/2/8/reviews/1022/figure/F1 (77 words)

	John M. Archibald: Curriculum Vitae
		Archibald, J.M. Phagotrophy in the Chlorarachniophyte* algae: implications for eukaryotic genome evolution.
		Phylogenetic studies suggest that the chlorarachniophyte endosymbiont was a chlorophyte green alga while the host cell was a member of a diverse group of eukaryotes called the Cercozoa.
		The chlorarachniophyte plastid proteome appears to be a mosaic of proteins derived from green algae (chlorophyte and streptophyte), red algae and bacteria.
	myweb.dal.ca /jmarchib/JMA.CV.html (2531 words)

	Diversity and evolutionary history of plastids and their hosts -- Keeling 91 (10): 1481 -- American Journal of Botany
		In cryptomonads and chlorarachniophytes, the primary algal nucleus is retained in a highly divergent form, called a nucleomorph, between the second and third membrane (in the space corresponding to the primary algal cytoplasm).
		that euglenid and chlorarachniophyte plastids are derived from
		Euglenids have three-membrane plastids, and chlorarachniophytes retain a nucleomorph.
	www.amjbot.org /cgi/content/full/91/10/1481 (7251 words)

	Why Sequence Guillardia theta and Bigelowiella natans?
		The goal of this proposal is to sequence the nuclear genomes of two microbial eukaryotes of pivotal evolutionary and cell biological significance, the cryptomonad Guillardia theta and the chlorarachniophyte Bigelowiella natans.
		Despite striking similarities in the size and structure of their nucleomorph genomes, the cryptomonads and chlorarachniophytes are the product of independent secondary endosymbiotic events involving different endosymbionts (red and green algae, respectively) and unrelated eukaryotic host cells.
		The limited coding capacity of cryptomonad and chlorarachniophyte nucleomorphs and plastids indicates that their nuclear genomes have been repositories for thousands of endosymbiont-derived genes throughout their evolutionary history.
	www.jgi.doe.gov /sequencing/why/CSP2007/guillardia.html (345 words)

	Bioinformatics & Evolutionary Genomics: Publications
		Chlorarachniophytes are amoeboid algae with chlorophyll a and b containing plastids that are surrounded by four membranes instead of two as in plants and green algae.
		These extra membranes form important support for the hypothesis that chlorarachniophytes have acquired their plastids by the ingestion of another eukaryotic plastid-containing alga.
		Chlorarachniophytes also contain a small nucleus-like structure called the nucleomorph situated between the two inner and the two outer membranes surrounding the plastid.
	bioinformatics.psb.ugent.be /paper_abstract.php?paper_id=69 (302 words)

	Postgenomic - Paper details
		BACKGROUND: The nucleomorphs associated with secondary plastids of cryptomonads and chlorarachniophytes are the sole examples of organelles with eukaryotic nuclear genomes.
		CONCLUSION: Chlorarachniophyte nucleomorph genes have accumulated errors at a faster rate than other genomes within the same cell, regardless of the compartment where the gene product functions.
		BackgroundThe nucleomorphs associated with secondary plastids of cryptomonads and chlorarachniophytes are the sole examples of organelles with eukaryotic nuclear genomes.
	www.postgenomic.com /paper.php?doi=10.1186/1471-2148-6-46 (321 words)

	CiteULike: A high frequency of overlapping gene expression in compacted eukaryotic genomes (Site not responding. Last check: 2007-10-30)
		The gene density of eukaryotic nuclear genomes is generally low relative to prokaryotes, but several eukaryotic lineages (many parasites or endosymbionts) have independently evolved highly compacted, gene-dense genomes.
		The best studied of these are the microsporidia, highly adapted fungal parasites, and the nucleomorphs, relict nuclei of endosymbiotic algae found in cryptomonads and chlorarachniophytes.
		We have conducted EST surveys of the microsporidian Antonospora locustae and nucleomorphs of the cryptomonad Guillardia theta and the chlorarachniophyte Bigelowiella natans.
	www.citeulike.org /user/cassj/article/270694 (524 words)

	ISEP meeting report for Protist
		Nucleomorphs, the vestigial nuclei of eukaryotic endosymbionts in cryptomonad and chlorarachniophyte algae, were a strong theme at this year's ISEP.
		Unlike the chlorarachniophyte nucleomorph, the cryptomonad nucleomorph is depauperate in introns, but both have otherwise very compact organization with miniature intergenic spacers.
		Both phylogenies were congruent showing that chlorarachniophytes comprise four distinct lineages exhibiting a range of cell forms: flagellates, reticulopodial amoebae and cysts.
	megasun.bch.umontreal.ca /isep/protista.html (3308 words)

	News & Features: (Abstract) Lateral transfer at the gene and subgenic levels in the evolution of ...
		We have examined enolases from a wide variety of algae, as well as ciliates (close relatives of apicomplexa), to determine whether lateral transfer can account for the origin of the apicomplexan enolase.
		We find that lateral gene transfer, likely occurring intracellularly between endosymbiont and host nucleus, does account for the evolution of cryptomonad and chlorarachniophyte algal enolases but fails to explain the apicomplexan enolase.
		This failure is because the phylogenetic distribution of the insertions-which we find in apicomplexa, ciliates, land plants, and charophyte green algae-directly conflicts with the phylogeny of the gene itself.
	www.iscid.org /boards/ubb-get_topic-f-1-t-000046.html (398 words)

	PDF files of papers- Geoff McFadden
		Gilson P. and McFadden G.I. (1995) The chlorarachniophyte - a cell with two different nuclei and two different telomeres.
		Gilson P., Waller R., and McFadden G. (1995) Preliminary characterisation of chlorarachniophyte mitochondrial DNA.
		Gilson P.R. and McFadden G.I. (1999) Molecular and morphological characterisation of six chlorarachniophyte strains.
	homepage.mac.com /fad1/PDFS.html (2381 words)

	From the Cover: Complete nucleotide sequence of the chlorarachniophyte nucleomorph: Nature's smallest nucleus -- Gilson ...
		From the Cover: Complete nucleotide sequence of the chlorarachniophyte nucleomorph: Nature's smallest nucleus -- Gilson et al.
		genome from the chlorarachniophyte Bigelowiella natans: at a
		Chlorarachniophyte plastids are thus serviced by three different
	www.pnas.org /cgi/content/short/103/25/9566?rss=1 (456 words)

	Untitled Document
		Gilson, P. and McFadden, G. (1996) The miniaturised nuclear genome of a eukaryotic endosymbiont contains genes that overlap, genes that are contranscribed, and smallest known spliceosomal introns.
		Gilson, P. and McFadden, G. (1999) Molecular and morphological characterization of six chlorarachniophyte strains.
		McFadden, G. Gilson, P. and Waller, R. Molecular phyologeny of chlorarachniophytes based on plastid rRNA and rbcL sequences.
	agrippina.bcs.deakin.edu.au /beech/Gilson.html (519 words)

	Lateral gene transfer and the evolution of plastid-targeted proteins in the secondary plastid-containing alga ...
		The chlorarachniophytes are a relatively small group of mixotrophic
		the chlorarachniophytes are distinguished by the retention of
		to assume that the acquisition of foreign genes by chlorarachniophytes
	www.pnas.org /cgi/content/full/100/13/7678 (3247 words)

	Green algae - Wikipedia, the free encyclopedia
		A few other organisms rely on green algae to conduct photosynthesis for them.
		The chloroplasts in euglenids and chlorarachniophytes were presumably acquired from ingested green algae, and in the latter retain a vestigial nucleus (nucleomorph).
		Some species of green algae, particularly of genera Trebouxia or Pseudotrebouxia (Trebouxiophyceae), can be found in symbiotic associations with fungi to form lichens.
	en.wikipedia.org /wiki/Green_alga (521 words)

	BioMed Central \| Full text \| Differential gene transfers and gene duplications in primary and secondary endosymbioses
		The secondary endosymbionts of a cryptomonad (Guillardia theta) and also a diatom (Odontella sinensis) are known to encode a single groEL gene in their plastid, and it can be speculated that the presence of a single copy of groEL may indicate the ancestral state in a primary endosymbiont [8,9].
		(e) In the nuclear genomes of a diatom (Thalassiosira pseudonana), an alveolate (Plasmodium falciparum), the higher plants and the nucleomorph genomes of a chlorarachniophyte (Bigelowiella natans), a cryptophyte (Guillarida theta) and a red algae (Cyanidoschyzon merolae) groEL2 type sequences are found.
		In a recently finished genome project on the nucleomorph genome of the chlorarachniophyte Bigelowiella natans (Gilson and McFadden, unpublished), a further nucleomorph-encoded cpn60 gene has been annotated.
	www.biomedcentral.com /1471-2148/6/38 (3225 words)

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