Transferència gènica horitzontal

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TRANSFERNCIA GNICA HORITZONTAL EN EUCARIOTES. Transferncia gnica horitzontal. Marta Puig Mdul de Genmica i Protemica. TGH/L: Definici. Es defineix com el moviment o transferncia dinformaci gentica a organismes que no sn els propis descendents. - PowerPoint PPT Presentation


Transmissi gnica horitzontal en levoluci dels eucariotes

Transferncia gnica horitzontal


Mdul de Genmica i ProtemicaTGH/L: DefiniciEs defineix com el moviment o transferncia dinformaci gentica a organismes que no sn els propis descendents.


Teoria de lendosimbiosi

Paulinella chromatophoraThe P. chromatophora symbiont was related to the Prochlorococcus and Synechococcus cyanobacteria (sister to the group consisting of the living members of those two genera).[3] Other than the symbiont, P. chromatophora is closely related to the heterotrophic P. ovalis3HGT: com es produeix?

TGH: com ho detectem? Incongruncies filogentiques

TGH: problemes per a detectar-laPrdua gnica diferencial

Artefactes en la reconstrucci filogentica

Degeneraci (milions danys)

Poca diferncia si es tracta de llinatges molt emparentats.

Duplicaci gnica ancestral

DGA: The second copy of the gene is often free from selective pressure that is, mutations of it have no deleterious effects to its host organism. Thus it accumulates mutations faster than a functional single-copy gene, over generations of organisms.6TGH: Generalitats No tots els gens/rutes metabliques tenen la mateixa probabilitat de ser transmesos.

Alguns, funcions clarament especialitzades (metabolisme anaerbic a diferents llinatges deucariotes).

Funcions ms generalistes: (D. discoideum, adaptaci al sl, 18 HGTs potencials).

TGH: Tipus Tenim diverses possibilitats

TGH: Tipus Procariotes Eucariotes.

Eucariotes Eucariotes (infraestimada?)

Procariotes orgnuls (molt estranya).

Orgnuls Nucli

Orgnul Orgnul

Eucariotes Procariotes (menys com que vice-versa: N molt ms grans en procariotes, altres mecanismes, poc inters pels gens eucaritics?).9Procariota Eucariotas la ms comuna (procariotes N molt grans), per en vertebrats (humans inclosos) sha posat en dubte per a un nombre important de gens.

Factors decisiu perqu es produeixi: contacte, connexi ntima amb el sistema vascular de lhoste, engoliment i digesti

Exemples: Saccharomyces cerevisiae. Gen DHOD adquirit de Lactobacilliales (prdua del DHOD nadiu) i DBS1 dels -proteobacteris.

DHOD: sntesi duracil en anaerobisi. DBS1: s del sulfat des de mltiples substrats orgnics.10Procariota EucariotaCromosoma 19 dOstreococcus tauri: no sassembla al daltres algues verdes. Sembla derivat completament dun altre llinatge!

With respect to chromosome 19, phylogenetic analysis shows thatonly 18% of the peptide-encoding genes are related to the greenlineage, a significantly lower percentage than that for the 19 otherchromosomes. Others resemble proteins from various origins,mainly bacterial, although generally poorly conserved (Fig. 3; andTable 8, which is published as supporting information on the PNASweb site). Interestingly, most (84%) of the ones having a documentedfunction belong to a few functional categories, primarilyencoding surface membrane proteins or proteins involved in thebuilding of glycoconjugates (Table 8). Based on these features, wehypothesize that chromosome 19 is of a different origin than the restof the genome. This putatively alien material could have yieldedsome selective advantages in cell surface processes, potentiallyrelated, for example, to defense against pathogens or other environmentalinteractions.11Eucariota Eucariota

Entre diferents llinatges de fongs (factors de virulncia, MAT loci al gnere Stemphylium).Entre diferents patgens de plantes (fongs filamentosos del flum ascomicets oomicets).Molts daquests gens provenen de procariotes: detecci ms fcil.

Eucariota Eucariota

Elysia chloroticaCargols marins fotosinttics: Aquireixen els cloroplasts duna espcie dalgues de la qual salimenten (Vaucheria litorea) i poden fer la fotosntesi amb lenergia solar: molt important en perodes descassetat, perqu poden emmagatzemen els sucres. Elysia no pot fabricar els cloroplasts per s sol, per tot indica que la seva capacitat de mantenir-los depn dalguns gens (psbO) que haurien passat al nucli per HGT, originalment provinents daquestes algues.13Orgnul OrgnulPlastidis: cap cas documentat dincorporaci de gens foranis (+ compactaci genoma).

Mitocondris: Relativament abundant.

Exemples: Citocrom b de mitocondris entre 3 espcies descarabats mexicans, plantes (parasitisme directe o b a travs de simbionts fngics).

We report on the probable horizontal transfer of a mitochondrial gene, cytb, between species of Neotropical bruchid beetles, in a zone where these species are sympatric. The high degree of incongruence of the cytb tree with patterns for other genes is discussed in the light of three hypotheses: experimental contamination, hybridization, and pseudogenisation. However, none of these seem able to explain the patterns observed. A fourth hypothesis, involving recent horizontal gene transfer (HGT) between A. obtectus and A. obvelatus, and from one of these species to Z. subfasciatus in the Mexican Altiplano, seems the only plausible explanation. The HGT between our study species seems to have occurred recently, and only in a zone where the three beetles are sympatric and share common host plants. This suggests that transfer could have been effected by some external vector such as a eukaryotic or viral parasite, which might still host the transferred fragment.

Three mitochondrial gene regions place this species with other ferns in Ophioglossaceae, while two regions place it as a member of the largely parasitic angiosperm order Santalales (sandalwoods and mistletoes). These discordant phylogenetic placements suggest that part of the genome in B. virginianum was acquired by horizontal gene transfer (HGT), perhaps from root-parasitic Loranthaceae. 14TGH: reconstrucci filogentica

Here, we present phylogenetic analyses of prolyl-tRNA and alanyl-tRNA synthetase genes that indicate lateral gene transfer events to an ancestor of the diplomonads and parabasalids from lineages more closely related to the newly discovered archaeal hyperthermophile Nanoarchaeum equitans (Nanoarchaeota) than to Crenarchaeota or Euryarchaeota. The support for this scenario is strong from all applied phylogenetic methods for the alanyl-tRNA sequences, whereas the phylogenetic analyses of the prolyl-tRNA sequences show some disagreements between methods, indicating that the donor lineage cannot be identified with a high degree of certainty. However, in both trees, the diplomonads and parabasalids branch together within the Archaea, strongly suggesting that these two groups of unicellular eukaryotes, often regarded as the two earliest independent offshoots of the eukaryotic lineage, share a common ancestor to the exclusion of the eukaryotic root. 15TGH i larbre de la vida

2.000s1.977BibliografiaStanhope, M. J., Lupas, A., Italia, M. J., Koretke, K. K., Volker, C., & Brown, J. R. (2001). Phylogenetic analyses do not support horizontal gene transfers from bacteria to vertebrates. Nature, 411(6840), 940-944.Bergthorsson, U., Adams, K. L., Thomason, B., & Palmer, J. D. (2003). Widespread horizontal transfer of mitochondrial genes in flowering plants. Nature, 424(6945), 197-201.Patron, N. J., Rogers, M. B., & Keeling, P. J. (2004). Gene replacement of fructose-1, 6-bisphosphate aldolase supports the hypothesis of a single photosynthetic ancestor of chromalveolates. Eukaryotic Cell, 3(5), 1169-1175.Andersson, J. O., Sarchfield, S. W., & Roger, A. J. (2005). Gene transfers from nanoarchaeota to an ancestor of diplomonads and parabasalids. Molecular biology and evolution, 22(1), 85-90.Davis, C. C., Anderson, W. R., & Wurdack, K. J. (2005). Gene transfer from a parasitic flowering plant to a fern. Proceedings of the Royal Society B: Biological Sciences, 272(1578), 2237-2242.Hall, C., Brachat, S., & Dietrich, F. S. (2005). Contribution of horizontal gene transfer to the evolution of Saccharomyces cerevisiae. Eukaryotic Cell, 4(6), 1102-1115.Richards, T. A., Dacks, J. B., Jenkinson, J. M., Thornton, C. R., & Talbot, N. J. (2006). Evolution of filamentous plant pathogens: gene exchange across eukaryotic kingdoms. Current Biology, 16(18), 1857-1864.Alvarez, N., Benrey, B., Hossaert-McKey, M., Grill, A., McKey, D., & Galtier, N. (2006). Phylogeographic support for horizontal gene transfer involving sympatric bruchid species. Biol. Direct, 1, 21. Derelle, E., Ferraz, C., Rombauts, S., Rouz, P., Worden, A. Z., Robbens, S., ... & Moreau, H. (2006). Genome analysis of the smallest free-living eukaryote Ostreococcus tauri unveils many unique features. Proceedings of the National Academy of Sciences, 103(31), 11647-11652.Keeling, Patrick J., and Jeffrey D. Palmer. "Horizontal gene transfer in eukaryotic evolution." Nature Reviews Genetics 9.8 (2008): 605-618.Nedelcu, A. M., Miles, I. H., Fagir, A. M., & Karol, K. (2008). Adaptive eukaryotetoeukaryote lateral gene transfer: stressrelated genes of algal origin in the closest unicellular relatives of animals. Journal of evolutionary biology, 21(6), 1852-1860.Schwartz, J. A., Curtis, N. E., & Pierce, S. K. (2010). Using algal transcriptome sequences to identify transferred genes in the sea slug, Elysia chlorotica. Evolutionary Biology, 37(1), 29-37.