Project description:Leishmania infantum is the causative agent of zoonotic visceral leishmaniasis in Mediterranean areas and also acts as an opportunistic parasite in HIV patients. Metacyclic promastigotes are transmitted during bloodmeals of the sand-fly host after development. Metacyclogenesis can be micmiked in axenic cultures and peanut lectin (PNA) agglutination followed by two-step centrifugation allows the separation of procyclic and metacyclic promastigotes in L. major. The purpose of this study is to isolate both fractions simultaneously from the same population of L. infantum in stationary phase of axenic culture and compare their expression profiles through DNA microarrays, specially focusing on metacyclic promastigotes. Whole-genome shotgun DNA microarrays were constructed and used to analyse the stationary-phase procyclic and metacyclic expression profiles. Four biological replicates of the experiment were performed and analysed, so that 322 clones with meaningful values of stage-specific regulation were selected. We found several genes dealing with primary metabolism, differentiation in procyclic promastigotes and with development of infectivity in metacyclic promastigotes. The differences we have found between the procyclic (PNA+) and metacyclic (PNA-) transcriptomes demonstrate that negative selection of metacyclic promastigotes through PNA agglutination is suitable in L. infantum and both fractions can be isolated. In addition, up-regulation of genes implied in lipophosphoglycan (LPG), proteophosphoglycan (PPG) and glycoprotein biosynthesis indicate that metacyclic promastigotes are related with infectivity. Keywords: comparative hybridization between cDNAs from procyclic PNA+ and metacyclic PNA- promastigotes of L.infantum
Project description:Leishmania infantum (Kinetoplastida:Trypanosomatidae) is the etiological agent of zoonotic visceral leishmaniasis in the Mediterranean basin. The motile promastigote stage infects the hematophagous sand fly vector host and amastigotes survives and multiplies within phagocytes of the mammalian host. Promastigotes are routinely cultured in liquid undefined media and are considered to mimic the environment within the sand fly gut. We have put this to the test by high-throughput gene expression profiling by shotgun DNA microarrays generated in our laboratory. This has been possible thanks to RNA amplification.
Project description:The DEAD/H RNA helicase LINF_220021200 (DEVH1) gene from Leishmania infantum (Kinetoplastida:Trypanosomatidae) was cloned in the pTEX expression plasmid vector for trypanosomatids. Leishmania infantunm promastigotes were transfected and a knock-in L. infantum promastigote cell line was selected with geneticin (G418). A pTEX control promastigote line was also generated. Then, three independent biological replicate cultures of each pTEX-DEVH1 and pTEX promastigote lines were performed in the presence of the selective agent. The parasites were harvested on day 7 (stationary phase). Total mRNA samples were obtained. Cyanine dye-labelled samples were obtained from the knock-in and the control line (Cy5 and Cy3, respectively) and they were hybridized with custom whole-genome L. infantum DNA microarrays. This platform is included in GEO (GPL6781) and has also been repeatedly used in different experiments from 2009. Hybridization analysis allowed for finding differentially expressed genes due to the effect of induced over-expression of the DEVH1-encoding gene in the knock-in promastigote line compared to the control line. Genes involved in parasite infectivity and survival such as the HASP/SHERP gene cluster and an amastin gene or redox homeostasis genes are significantly down-regulated in the pTEX-DEVH1 knock-in promastigote line, whereas genes related to growth are up-regulated. This is in agreement with previous experimental data supporting that L. infantum DEVH1 knock-in promastigotes are able to recover the growth rate when stress conditions are removed.
Project description:Protozoan parasites of the genus Leishmania are causative agents of leishmaniasis, a wide range of diseases affecting 12 million people worldwide. The species L. (L.) infantum and L. (L.) amazonensis are causative agents of visceral and cutaneous leishmaniasis, respectively. Most proteome analyses of Leishmania have been carried out on whole-cell extracts. However, this approach tends to underrepresent membrane-associated proteins because of their high hydrophobicity and low solubility. Due to the great importance of membrane-associated proteins in biological processes, including host–parasite interactions, virulence and invasiveness, this study applied label-free shotgun proteomics to characterize and evaluate abundance levels of plasma membrane sub-proteome of promastigotes life-stage. The total number of proteins identified in L. (L.) infantum and L. (L.) amazonensis was 2033 and 2243, respectively. Both species shared 1908 of these quantified proteins. After cell localization prediction of all identified proteins, 394 proteins were described as plasma membrane-associated proteins and their majority (320 proteins) was presented in both species. Considering only exclusive proteins, 18 proteins were detected only in L. (L.) infantum and 56 proteins in L. (L.) amazonensis. We used two criteria to define “regulated” proteins; i) proteins with p-value < 0.05 after One-Way ANOVA analysis (quantitative analysis) and proteins detected only in L. (L.) infantum or L. (L.) amazonensis (qualitative analysis).