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Topic: Endosymbiont

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  Endosymbiont - Wikipedia, the free encyclopedia
The endosymbiont theory explains the origins of organelles such as mitochondria and chloroplasts in eukaryotic cells.
Dinoflagellate endosymbionts of the genus Symbiodinium, commonly known as zooxanthellae, are found in corals, mollusks (esp. giant clams, the Tridacna), sponges, and foraminifera.
Genome sequencing reveals that obligate bacterial endosymbionts of insects have among the smallest of known bacterial genomes and have lost many genes that are commonly found in closely related bacteria.
en.wikipedia.org /wiki/Endosymbiont   (2117 words)

 Endosymbiont theory   (Site not responding. Last check: 2007-10-20)
Endosymbionts must originally have had a larger set of genes, sufficient for autonomous growth.
The endosymbiont theory was proposed by Lynn Margulis.
An alternate view is that eukaryotes arose by fusion of a eubacterium with an archaebacterium with some of the eubacterial genes winding up in the ancestor of mitochondria (ref).
opbs.okstate.edu /~melcher/MG/MGW1/MG1378.html   (297 words)

 The ultrastructural study of Lepidodinium viride and its endosymbiont
The pigmentation of this organism is due to an endosymbiont harboured within Lepidodinium, which many generations before had been acquired by phagocytosis (the ingestion of particles).
The cells therefore have a bright-green appearance as opposed to the usual brown pigmentation of dinoflagellates.
The presence of both chlorophyll b and prasinoxanthin leads to the assumption that the endosymbiont may be of prasinophytic origin.
www.botany.uwc.ac.za /pssa/articles/students/no54-dukhan.htm   (582 words)

 A More Perfect Union.(relationship of insects and bacteria) - Science News - HighBeam Research   (Site not responding. Last check: 2007-10-20)
Wernegreen expects that as more endosymbiont genomes are sequenced, they will show a consistent pattern of gene loss, just as disease-causing bacteria living permanently inside cells lose a consistent set of genes.
This secondary endosymbiont might therefore have arisen from a pathogen that had evolved to live as a parasite inside the insects' cells, he suggests.
Rather, as secondary endosymbionts wielding vital genomes replace the shrinking genomes of the primaries, he says, it may be the individual genes for indispensable functions that achieve immortality through successive waves of their bearers.
highbeam.com /doc/1G1:75434920/A+More+Perfect+Union.(relationship+...   (2480 words)

 Online Encyclopedia and Dictionary - Endosymbiont
5.3 Symbiodinium dinoflagellate endosymbionts in marine metazoa and protists
In marine oligochaetes (e.g Olavius or Inanidrillus) the endosymbionts are extracellular and they fill the entire body of their host.
Dinoflagellate endosymbionts of the genus Symbiodinium, commonly known as zooxanthellae, are found in corals, molluscs (esp. giant clams, the Tridacna), and foraminifera.
fact-archive.com /encyclopedia/Endosymbiont   (1193 words)

 MBL Astrobiology Portal
In contrast to the genomes of mutualistic endosymbionts that traditionally show strict vertical transmission and efficient streamlining of selfish and mobile DNA, we predict that the genomes of more labile endosymbionts, that for instance undergo some horizontal transmission, may show more chromosomal plasticity.
The latter may be especially common and profoundly important to host genome evolution, since endosymbionts are often intimately associated with host cells in the germline.
Sperm are modified by the bacteria in the testes and unless the egg carries the same strain, the paternal genome improperly condenses in the fertilized egg and inviability results.
astrobiology.mbl.edu /proj-arch_evol.html   (1289 words)

 Ask A Scientist - Organelles
An endosymbiont is an organism that lives inside a larger organism in a symbiotic relationship.
The endosymbiont hypothesis proposes that long ago, free-living bacteria either invaded another cell or were swallowed by it.
Eventually, in the descendants of the original endosymbionts, most of the bacterial genes were lost or transferred to the host's chromosomes, and the bacteria became specialized components of their host cells: organelles.
www.hhmi.org /cgi-bin/askascientist/highlight.pl?kw=&file=answers/general/ans_033.html   (446 words)

 Genetics notes
Cell physiology in certain cells of the weevil Sitophilus oryzae is coordinated by four integrated genomes: the nuclear genome, the mitochondrial genome, the genome of a principal endosymbiont, and the genome of a secondary endosymbiont.
In contrast, the secondary endosymbiont has no discernible effect the physiology of the weevil, although certain genetic effects of the organism are evident under special experimental circumstances: they suggest an involvement in the speciation of the weevil.
The secondary weevil endosymbiont is a virus -- a rickettsia-like organism widespread in arthropods.
cogweb.ucla.edu /ep/Genetics.html   (699 words)

 NAI: Year 5 Annual Report: Marine Biological Laboratory   (Site not responding. Last check: 2007-10-20)
Today, bacterial endosymbionts allow numerous animal, plant, and protist lineages to occupy niches that are otherwise inhospitable.
Bacterial endosymbionts of diverse insects show similar patterns of genome reduction, strong AT mutational bias, and effects of genetic drift on protein evolution.
We found strong effects of genetic drift at even the most conserved endosymbiont loci, suggesting that no genes are immune from this degradative process.
nai.arc.nasa.gov /year5/year4.cfm?PageAction=5&Section=11&Page=20&Proj=506   (682 words)

 'Candidatus Glomeribacter gigasporarum' gen. nov., sp. nov., an endosymbiont of arbuscular mycorrhizal fungi -- ...
amplification of spore DNA from endosymbionts of Gigaspora margarita,
Numerous bacterial endosymbionts separated from the fungal cytoplasm by crushing and centrifugation of Gigaspora margarita BEG 34 spores.
The endosymbionts of four fungal isolates were examined further.
ijs.sgmjournals.org /cgi/content/full/53/1/121   (2007 words)

 Endosymbiont change as a key innovation in the adaptive radiation of Soritida (Foraminifera) -- Richardson 27 (2): 262 ...
Endosymbiont change as a key innovation in the adaptive radiation of Soritida (Foraminifera)
to chlorophyte endosymbionts occurred in the stem lineage of
on the cladogram of Soritida, the acquisition of dinophyte endosymbionts
paleobiol.geoscienceworld.org /cgi/content/abstract/27/2/262   (263 words)

 Molecular characterization and endosymbiotic localization of the gene encoding D-ribulose 1,5-bisphosphate ...
in the endosymbiont of the vent tubeworm Ridgeia spp.
of cbbM and the absence of cbbL in the tubeworm endosymbiont
The amino acids that were identical in all of the aligned sequences are marked with asterisks, conserved substitutions are marked with colons, and semi-conserved substitutions are marked with periods.
mic.sgmjournals.org /cgi/content/full/148/6/1947   (5330 words)

 Degenerate mitochondria   (Site not responding. Last check: 2007-10-20)
The original interaction between the endosymbiont and host resulted in the transfer of endosymbiont genes to the host nucleus and the irreversible loss of redundant genes (Adams and Palmer, 2003; Timmis et al, 2004).
The second invokes two serial endosymbiotic events: one that led to the acquisition of the original mitochondrial endosymbiont, and the other, subsequent to the loss of the original mitochondrial endosymbiont, that led to the formation of a chimerical organelle that evolved into hydrogenosomes and/or mitosomes (Dyall et al, 2004a,b).
Direct evolution from the mitochondrial endosymbiont explains the presence of the limiting double membrane that surrounds mitochondrion-related organelles and the functionally conserved mechanisms of protein import into hydrogenosomes, mitosomes and mitochondria.
www.nature.com /cgi-taf/DynaPage.taf?file=/embor/journal/v6/n6/full/7400440.html   (3753 words)

 Increased Rates of Sequence Evolution in Endosymbiotic Bacteria and Fungi with Small Effective Population Sizes -- ...
Buchnera, the endosymbionts of aphids (Moran 1996; Brynnel et al.
The A + T-rich genomes of Buchnera and Wigglesworthia (the endosymbiont
Phylogenetic characterization and molecular evolution of bacterial endosymbionts in psyllids (Hemiptera : Sternorrhyncha).
mbe.oxfordjournals.org /cgi/content/full/20/9/1545   (5240 words)

 Cospeciation of Psyllids and Their Primary Prokaryotic Endosymbionts -- Thao et al. 66 (7): 2898 -- Applied and ...
Psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity.
Structure and evolution of the leucine plasmids carried by the endosymbiont (Buchnera aphidicola) from aphids of the family Aphididae.
Phylogenetic characterization and molecular evolution of bacterial endosymbionts in psyllids (Hemiptera: Sternorrhyncha).
aem.asm.org /cgi/content/full/66/7/2898   (5306 words)

 Evolutionary Relationships of Primary Prokaryotic Endosymbionts of Whiteflies and Their Hosts -- Thao and Baumann 70 ...
Sequence analysis of DNA fragments from the genome of the primary endosymbiont of Bemisia tabaci.
The eubacterial endosymbionts of whiteflies (Homoptera: Aleyrodoidea) constitute a lineage distinct from the endosymbionts of aphids and mealybugs.
Cospeciation between bacterial endosymbionts (Buchnera) and a recent radiation of aphids (Uroleucon) and pitfalls of testing for phylogenetic congruence.
aem.asm.org /cgi/content/full/70/6/3401   (3270 words)

 Endosymbiont Phylogenesis in the Dryophthoridae Weevils: Evidence for Bacterial Replacement -- Lefèvre et al. 21 ...
Endosymbiont Phylogenesis in the Dryophthoridae Weevils: Evidence for Bacterial Replacement -- Lefèvre et al.
on Sodalis glossinidius, the secondary endosymbiont of the tsetse
Wernegreen, J. Genome evolution in bacterial endosymbionts of insects.
mbe.oxfordjournals.org /cgi/content/full/21/6/965   (4213 words)

 Genome Evolution in an Insect Cell: Distinct Features of an Ant-Bacterial Partnership -- Wernegreen et al. 204 (2): 221 ...
Physical and genetic map of the genome of Buchnera, the primary endosymbiont of the pea aphid Acyrthosiphon pisum.
Phylogenetic characterization and molecular evolution of bacterial endosymbionts in psyllids (Hemiptera:Sternorrhyncha).
Vertical transmission of biosynthetic plasmids in aphid endosymbionts (Buchnera).
www.biolbull.org /cgi/content/full/204/2/221   (5987 words)

 Reference   (Site not responding. Last check: 2007-10-20)
Complete genome DNA sequence and analysis is presented for Wolbachia, the obligate alpha-proteobacterial endosymbiont required for fertility and survival of the human filarial parasitic nematode Brugia malayi.
Genome comparison of the Wolbachia endosymbiont of B. malayi (wBm) with the Wolbachia endosymbiont of Drosophila melanogaster (wMel) shows that they share similar metabolic trends, although their genomes show a high degree of genome shuffling.
Analysis of this first sequenced endosymbiont genome from a filarial nematode provides insight into endosymbiont evolution and additionally provides new potential targets for elimination of cutaneous and lymphatic human filarial disease.
www.cbs.dtu.dk /services/GenomeAtlas/show-medline.php?kingdom=Bacteria&segmentid=Wendosymbiont_TRS_Main   (352 words)

 ARS | Publication request: Preliminary Description of a Bacterial Endosymbiont of Soybean Cyst Nematode, Heterodera ...
This endosymbiont, which parastizes wasps of the genus Encarsia was described in 2004.
The endosymbiont of H. glycines has brush-like arrays of microfilament-like structures characteristic of the genus Cardinium.
However, a dissimilarity index of 7% with C. hertigii indicates that the endosymbiont of H. glycines is a new species.
www.ars.usda.gov /research/publications/Publications.htm?seq_no_115=168291   (267 words)

 Coupling of Bacterial Endosymbiont and Host Mitochondrial Genomes in the Hydrothermal Vent Clam Calyptogena magnifica ...
Identification and localization of bacterial endosymbionts in hydrothermal vent taxa with symbiont-specific polymerase chain reaction amplification and in situ hybridization techniques.
Occurrence of bacteria in the primary oocytes of vesicomyid clam Calyptogena soyoae.
Environmental transmission of sulfur-oxidizing bacterial gill endosymbiont in the tropical lucinid bivalve Codakia orbicularis.
aem.asm.org /cgi/content/full/69/4/2058   (3581 words)

 Small genome of Candidatus Blochmannia, the bacterial endosymbiont of Camponotus, implies irreversible specialization ...
Charles, H. and Ishikawa, H. Physical and genetic map of the genome of Buchnera, the primary endosymbiont of the pea aphid Acyrthosiphon pisum.
Charles, H., Heddi, A. and Rahbe, Y. A putative insect intracellular endosymbiont stem clade, within the Enterobacteriaceae, infered from phylogenetic analysis based on a heterogeneous model of DNA evolution.
Sauer, C., Stackebrandt, E., Gadau, J., Holldobler, B. and Gross, R. Systematic relationships and cospeciation of bacterial endosymbionts and their carpenter ant host species: proposal of the new taxon Candidatus Blochmannia gen. nov.
mic.sgmjournals.org /cgi/content/full/148/8/2551   (2451 words)

 Micro 200 Quiz 9   (Site not responding. Last check: 2007-10-20)
B. Reduction of sulfate to sulfide for the endosymbiont to oxidize.
D. Calvin cycle that provides the endosymbiont with complex carbon sources.
The bacterium Wolbachia is an endosymbiont which causes fertility incompatibility in the fruit fly.
www.life.uiuc.edu /micro/advisor/mcbio200/02_sp/quiz_09.html   (167 words)

 [No title]   (Site not responding. Last check: 2007-10-20)
Chlorarachniophytes are unicellular amoeboflagellates that contain a photosynthetic, eukaryotic endosymbiont probably derived from a primitive green alga.
The endosymbiont, nested within the host cell's cytoplasm, contains little more than a chloroplast, a small volume of cytoplasm surrounding a tiny nucleus called the nucleomorph, and a plasma membrane.
The nucleomorph genome is a mere 380kb in size and consists of three linear chromosomes (diagram of karyotype) that are capped with typical eukaryotic telomeres.
homepage.mac.com /fad1/Chlorarachnion.html   (429 words)

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