Histochem Cell Biol (2008) 130:1187–1198 DOI 10.1007/s00418-008-0486-8 123 ORIGINAL PAPER All Trypanosoma cruzi developmental forms present lysosome-related organelles Celso Sant’Anna · Fabiola Parussini · Daniela Lourenço · Wanderley de Souza · Juan Jose Cazzulo · Narcisa Leal Cunha-e-Silva Accepted: 27 July 2008 / Published online: 12 August 2008  Springer-Verlag 2008 Abstract Trypanosoma cruzi epimastigote forms concen- trate their major protease, cruzipain, in the same compart- ment where these parasites store macromolecules obtained from medium and for this ability these organelles were named as reservosomes. Intracellular digestion occurs mainly inside reservosomes and seems to be modulated by cruzipain and its natural inhibitor chagasin that also con- centrates in reservosomes. T. cruzi mammalian forms, try- pomastigotes and amastigotes, are unable to capture macromolecules by endocytosis, but also express cruzipain and chagasin, whose role in infectivity has been described. In this paper, we demonstrate that trypomastigotes and amastigotes also concentrate cruzipain, chagasin as well as serine carboxypeptidase in hydrolase-rich compartments of acidic nature. The presence of P-type proton ATPase indicates that this compartment is acidiWed by the same enzyme as epimastigote endocytic compartments. Elec- tron microscopy analyzes showed that these organelles are placed at the posterior region of the parasite body, are single membrane bound and possess an electron-dense matrix with electronlucent inclusions. Three-dimensional reconstruction showed that these compartments have diVerent size and shape in trypomastigotes and amastigotes. Based on these evidences, we suggest that all T. cruzi developmental stages present lysosome-related organelles that in epimastigotes have the additional and unique ability of storing cargo. Keywords Lysosome-related organelles · Reservosomes · Serine carboxypeptidase · Trypomastigotes · Amastigotes · Trypanosoma cruzi Introduction The trypanosomatid parasites have diVerent developmental stages that represent an adaptation to the extra and intra- cellular environments encountered by the parasites within their two hosts, the mammalian host and the insect vector. Endocytosis and protein turnover are essential metabolic pathways for life cycle development of Trypanosoma cruzi, the etiologic agent of Chagas disease (De Souza et al. 2002). The endocytic pathway is under strict developmental control in the diVerent life cycle stages of the parasite. Epimastigotes, proliferative forms found inside insect host, are highly active in Xuid phase and receptor mediated path- ways, and store macromolecules up taken from the medium inside the reservosomes (Soares and De Souza 1991). The pathway has not been observed in either trypomastigotes, C. Sant’Anna · D. Lourenço · W. de Souza · N. L. Cunha-e-Silva (&) Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Bloco G subsolo, Cidade Universitária, Ilha do Fundão, Rio de Janeiro 21949-900, Brazil e-mail: narcisa@biof.ufrj.br C. Sant’Anna · W. de Souza Diretoria de Programas (DIPRO), INMETRO, Rio de Janeiro, Brazil F. Parussini · J. J. Cazzulo Instituto de Investigaciones Biotecnológicas, Instituto Tecnológico de Chascomús, Universidad Nacional de General San Martín, CONICET, Av. General Paz 5445, INTI, EdiWcio 24, Casilla de Correo 30, 1650 San Martín, Provincia de Buenos Aires, Argentina Present Address: F. Parussini Microbiology and Molecular Genetics, University of Vermont, 316 StaVord Hall, 95 Carrigan Drive, Burlington, VT 05405, USA