English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Background  African trypanosomes cause lethal diseases in humans and animals and escape host immune attack by switching the expression of Variant Surface Glycoprotein (VSG) genes. The expressed  VSGs  are located at the ends of telomeric, polycistronic transcription units known as  VSG  expression sites ( VSG -ESs). Each cell has many  VSG -ESs but only one is transcribed in bloodstream-form parasites and all of them are inactive upon transmission to the insect vector mid-gut; a subset of monocistronic metacyclic  VSG- ESs are then activated in the insect salivary gland. Deep-sequence analyses have been informative but assigning sequences to individual  VSG -ESs has been challenging because they each contain closely related expression-site associated genes, or  ESAGs,  thought to contribute to virulence.    Results  We utilised ART, an  in silico  short read simulator to demonstrate the feasibility of accurately aligning reads to  VSG -ESs. Then, using high-resolution transcriptomes from isogenic bloodstream and insect-stage Lister 427  Trypanosoma brucei , we uncover increased abundance in the insect mid-gut stage of mRNAs from metacyclic  VSG- ESs and of mRNAs from the unusual  ESAG, ESAG10 . Further, we show that the silencing associated with allelic exclusion involves repression focussed at the ends of the  VSG -ESs. We also use the approach to report relative fitness costs following  ESAG  RNAi from a genome-scale screen.    Conclusions  By assigning sequences to individual  VSG -ESs we provide new insights into  VSG -ES transcription control, allelic exclusion and impacts on fitness. Thus, deeper insights into the expression and function of regulated multi-gene families are more accessible than previously anticipated.    Electronic supplementary material  The online version of this article (doi:10.1186/s12864-016-3154-8) contains supplementary material, which is available to authorized users.

High-resolution analysis of multi-copy variant surface glycoprotein gene expression sites in African trypanosomes