title: Trypanosoma cruzi epimastigotes are able to store and mobilize high amounts of cholesterol in reservosome lipid inclusions.
abstract: BACKGROUND
  Reservosomes are lysosome-related organelles found in Trypanosoma cruzi epimastigotes. They represent the last step in epimastigote endocytic route, accumulating a set of proteins and enzymes related to protein digestion and lipid metabolism. The reservosome matrix contains planar membranes, vesicles and lipid inclusions. Some of the latter may assume rectangular or sword-shaped crystalloid forms surrounded by a phospholipid monolayer, resembling the cholesterol crystals in foam cells.
  
  
  RESULTS
  Using Nile Red fluorimetry and fluorescence microscopy, as well as electron microscopy, we have established a direct correlation between serum concentration in culture medium and the presence of crystalloid lipid inclusions. Starting from a reservosome purified fraction, we have developed a fractionation protocol to isolate lipid inclusions. Gas-chromatography mass-spectrometry (GC-MS) analysis revealed that lipid inclusions are composed mainly by cholesterol and cholesterol esters. Moreover, when the parasites with crystalloid lipid-loaded reservosomes were maintained in serum free medium for 48 hours the inclusions disappeared almost completely, including the sword shaped ones.
  
  
  CONCLUSIONS
  Taken together, our results suggest that epimastigote forms of T. cruzi store high amounts of neutral lipids from extracellular medium, mostly cholesterol or cholesterol esters inside reservosomes. Interestingly, the parasites are able to disassemble the reservosome cholesterol crystalloid inclusions when submitted to serum starvation.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Miria G
authors.initials: MG
authors.lastname: Pereira
authors.forename: Ernesto S
authors.initials: ES
authors.lastname: Nakayasu
authors.forename: Celso
authors.initials: C
authors.lastname: Sant'Anna
authors.forename: Nuccia N T
authors.initials: NN
authors.lastname: De Cicco
authors.forename: Georgia C
authors.initials: GC
authors.lastname: Atella
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.forename: Igor C
authors.initials: IC
authors.lastname: Almeida
authors.forename: Narcisa
authors.initials: N
authors.lastname: Cunha-e-Silva
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D005470:Fluorometry; D002479:Inclusion Bodies / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008018:Life Cycle Stages / Q000187:drug effects; D008856:Microscopy, Fluorescence; D010078:Oxazines / Q000378:metabolism; D013997:Time Factors; D014349:Trypanosoma cruzi / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D016895:Culture Media, Serum-Free; D010078:Oxazines; D002784:Cholesterol; C044808:nile red