Encystation process of Giardia lamblia : morphological and regulatory aspects
- PDF / 575,505 Bytes
- 7 Pages / 595 x 791 pts Page_size
- 92 Downloads / 215 Views
ORIGINAL PAPER
Encystation process of Giardia lamblia: morphological and regulatory aspects Joana Bittencourt-Silvestre · Leandro Lemgruber · Wanderley de Souza
Received: 19 November 2009 / Revised: 24 January 2010 / Accepted: 27 January 2010 / Published online: 12 February 2010 © Springer-Verlag 2010
Abstract One important step in the life cycle of the pathogenic protozoan Giardia lamblia is the transformation of the proliferative form, the trophozoite, into the non-proliferative cyst. This process, known as encystation, can be triggered in vitro. Morphological analysis showed that during trophozoite-cyst transformation, major changes take place: modiWcation of the protozoan shape, internalization of the Xagella, fragmentation of the adhesive disk, and appearance of encystation vesicles (ESVs), which later on fuse with the plasma membrane forming the cell wall. Sites of attachment of these vesicles to the inner portion of the protozoan plasma membrane were observed 6 h after the beginning of the encystation process. These sites were only visible when we used high-resolution scanning electron microscopy to study Giardia surface. In order to analyze the involvement of protein kinases and phosphatases on the encystation process, inhibitors of these enzymes were added to the culture medium, and their eVect on the diVerentiation process was determined using light, immunoXuorescence, and electron microscopy. SigniWcant inhibition was observed with LY294002, an inhibitor of PI3 kinase; Communicated by Erko Stackebrandt. J. Bittencourt-Silvestre · L. Lemgruber · W. de Souza (&) Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av Carlos Chagas Filho 341, CCS, Bloco G, Rio de Janeiro, RJ 21941-902, Brazil e-mail: [email protected] W. de Souza Instituto Nacional de Metrologia, Normalização e Qualidade Industrial, Rio de Janeiro, Brazil J. Bittencourt-Silvestre · L. Lemgruber · W. de Souza Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil
genistein, an inhibitor of tyrosine kinase; and staurosporine, at concentrations, which inhibit protein kinase C. Okadaic acid, an inhibitor or protein phosphatase, and wortmannin, an inhibitor of PI3K, did not interfere with the encystation process. However, they induced the appearance of large and pleomorphic forms where several nuclei and disorganization of the peripheral vesicles were observed. Keywords Giardia · Encystment · Protein kinase · Protozoan diVerentiation · High-resolution scanning electron microscopy
Introduction Giardia lamblia (syn. Giardia duodenalis, Giardia intestinalis) is a cosmopolitan protozoan parasite and the causative agent of giardiasis, a disease that aVects mainly children between 1 and 4 years old, leading to malabsorption and diarrhea (Adam 2001; Hlavsa et al. 2005). The trophozoites colonize the small intestine of mammals and after exposure to biliary Xuids; some of them undergo an encystation process and become cy
Data Loading...
