Project description:Trypanosomes are a globally important group of parasites which together kill and debilitate millions of people world-wide. In trypanosomes, genes do not have individual promoters, rather ~10000 genes share ~200 promoters and all gene expression is thus regulated post-transcriptionally. While effector proteins which modulate the expression of many genes have been described, the mechanisms by which trypanosomes sense changes in their environment and manifest changes in gene expression remain elusive. This study demonstrates that trypanosomes sense changes in their environment through temperature sensitive RNA secondary structure. We show that the majority of observed mRNA abundance changes which distinguish insect adapted and bloodstream adapted life cycle stages can be explained through change in temperature alone.
Project description:Trypanosomes are a globally important group of parasites which together kill and debilitate millions of people world-wide. In trypanosomes, genes do not have individual promoters, rather ~10000 genes share ~200 promoters and all gene expression is thus regulated post-transcriptionally. While effector proteins which modulate the expression of many genes have been described, the mechanisms by which trypanosomes sense changes in their environment and manifest changes in gene expression remain elusive. This study demonstrates that trypanosomes sense changes in their environment through temperature sensitive RNA secondary structure. We show that the majority of observed mRNA abundance changes which distinguish insect adapted and bloodstream adapted life cycle stages can be explained through change in temperature alone.
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance
Project description:A direct comparison of RNAi in vitro with RNAi in vivo is being performed using RNA interference (RNAi) target sequencing (RIT-Seq) of Trypanosoma brucei to identify all genes specifically required for growth in vivo (the infectome). Assembly of the bloodstream-form T. brucei RNAi library and the RNAi target sequencing (RIT-seq) approach in African trypanosomes were reported previously in Alsford, S. et al. High-throughput phenotyping using parallel sequencing of RNA interference targets in the African trypanosome. Genome Res 21, 915-924, 264 doi:gr.115089.110 [pii] 265 10.1101/gr.115089.110 (2011) and Alsford,S et al. High-throughput decoding of antitrypanosomal drug efficacy and resistance. Nature 482, 232236 doi:10.1038/nature10771 (2012). This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
Project description:Trypanosomes were sorted (0 cells, 1 cell, 50 cells) using a FACSaria III (BD Biosciences; precision: single-cell; nozzle: 100 µm). Forward-scatter area (FCS-A) versus side-scatter area (SSC-A) was used to gate the cells. Trypanosomes were sorted in 48-wells plate (Brand) filled with 2.6 µL of lysis buffer (0.01 µL of RNAse inhibitor (Takara) and 1x Lysis buffer (Takara) in RNAse-free water). Immediately after sorting cells were placed on ice for 5 minutes and stored at -80 °C. 50 and single trypanosomes were prepared using SMART-Seq v4 Ultra Low Input RNA Kit (Takara) using one fourth of reagents volumes compared to the supplier instructions. PCR amplification was performed using 26 cycles using supplier recommendations. cDNA was purified using XP beads (Beckman Coulter) and recovered in 15 µL of elution buffer (Takara). Libraries were quantified using the Qubit Hs Assay (Life Technologies) and the qualities of the libraries were further monitored using a Bioanalyzer (Agilent). Similar to what has been published previously 19, 1 ng of cDNA was subjected to a tagmentation-based protocol (Nextera XT, Illumina) using one-quarter of the recommended volumes, 10 minuntes for tagmentation at 55 °C and 1 minute extension time during PCR amplification. Libraries were pooled (96 libraries for NextSeq) and sequencing was performed in paired-end mode for 2 × 75 cycles using Illumina's NextSeq 500.
Project description:Trypanosoma brucei gambiense is the causative agent of the fatal human disease African sleeping sickness. Using Digital Gene Expression we have compared the transcriptome of a group 1 T.b.gambiense (Eliane) and a T.b.brucei (STIB 247).
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance Bloodstream stages of the Lister strain 427 T. b. brucei (MiTat 1.2), expressing VSG221, were used in these studies. Cells were cultured in HMI-9 medium with the addition of heat inactivated fetal bovine serum (FBS) (10%) and Serum Plus (10%). T. b. brucei 427-221 is an antigenically stable line and contains a single copy of the vsg221 gene within the 221 expression site (221ES). At a cell density of approximately 1,000,000 cells/ml, T. b. brucei 427-221 were exposed to various amounts of human HDLs for 24 h in a 6 well plate. Surviving trypanosomes were counted using a hemocytometer then diluted into fresh HMI-9 medium and allowed to recover for 5-14 days. Once the cells had grown to a density of approximately 1,000,000 cells/ml, they were once again incubated with human HDLs. Each round of selection was performed with increasing concentrations of human HDLs and freezer stocks were prepared for each surviving population. Over nine months we conducted eight rounds of human HDL selection, resulting in a population of T. b. brucei that survived incubation with 800 μl of human HDLs (160 lytic U).
Project description:Trypanosomes were sorted (1 cell, 10 cells, 50 cells) using a FACSaria III (BD Biosciences; precision: single-cell; nozzle: 100 µm). Forward-scatter area (FCS-A) versus side-scatter area (SSC-A) was used to gate the cells. Trypanosomes were sorted in 48-wells plate (Brand) filled with 2.6 µL of lysis buffer (0.01 µL of RNAse inhibitor (Takara) and 1x Lysis buffer (Takara) in RNAse-free water). Immediately after sorting cells were placed on ice for 5 minutes and stored at -80 °C. 50 and single trypanosomes were prepared using SMART-Seq v4 Ultra Low Input RNA Kit (Takara) using one fourth of reagents volumes compared to the supplier instructions. PCR amplification was performed using 26 cycles using supplier recommendations. cDNA was purified using XP beads (Beckman Coulter) and recovered in 15 µL of elution buffer (Takara). Libraries were quantified using the Qubit Hs Assay (Life Technologies) and the qualities of the libraries were further monitored using a Bioanalyzer (Agilent). Similar to what has been published previously 19, 1 ng of cDNA was subjected to a tagmentation-based protocol (Nextera XT, Illumina) using one-quarter of the recommended volumes, 10 minuntes for tagmentation at 55 °C and 1 minute extension time during PCR amplification. Libraries were pooled (96 libraries for NextSeq) and sequencing was performed in paired-end mode for 2 × 75 cycles using Illumina's NextSeq 500.