Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdumReportar como inadecuado




Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

BMC Genomics

, 9:385

First Online: 12 August 2008Received: 16 May 2008Accepted: 12 August 2008

Abstract

BackgroundAfrican trypanosomes including Trypanosoma brucei are unicellular parasites which multiply in the mammalian bloodstream. T. brucei has about twenty telomeric bloodstream form Variant Surface Glycoprotein VSG expression sites BESs, of which one is expressed at a time in a mutually exclusive fashion. BESs are polycistronic transcription units, containing a variety of families of expression site associated genes ESAG s in addition to the telomeric VSG. These polymorphic ESAG families are thought to play a role in parasite-host adaptation, and it has been proposed that ESAG diversity might be related to host range. Analysis of the genetic diversity of these telomeric gene families has been confounded by the underrepresentation of telomeric sequences in standard libraries. We have previously developed a method to selectively isolate sets of trypanosome BES containing telomeres using Transformation associated recombination TAR cloning in yeast.

ResultsHere we describe the isolation of repertoires of BES containing telomeres from three trypanosome subspecies: Trypanosoma brucei gambiense DAL 972 causative agent of West-African trypanosomiasis, T. b. brucei EATRO 2340 a nonhuman infective strain and T. equiperdum STIB 818 which causes a sexually transmitted disease in equines. We have sequenced and analysed the genetic diversity at four BES loci BES promoter region, ESAG6, ESAG5 and ESAG2 from these three trypanosome BES repertoires.

ConclusionWith the exception of ESAG2, the BES sequence repertoires derived from T. b. gambiense are both less diverse than and nearly reciprocally monophyletic relative to those from T. b. brucei and T. equiperdum. Furthermore, although we find evidence for adaptive evolution in all three ESAG repertoires in T. b. brucei and T. equiperdum, only ESAG2 appears to be under diversifying selection in T. b. gambiense. This low level of variation in the T. b. gambiense BES sequence repertoires is consistent both with the relatively narrow host range of this subspecies and its apparent long-term clonality. However, our data does not show a clear correlation between size of trypanosome host range and either number of BESs or extent of ESAG genetic diversity.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2164-9-385 contains supplementary material, which is available to authorized users.

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Autor: Rosanna Young - Jesse E Taylor - Ayako Kurioka - Marion Becker - Edward J Louis - Gloria Rudenko

Fuente: https://link.springer.com/article/10.1186/1471-2164-9-385







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