Video-Microscopy Observations of Fast Dynamic Processes in the Protozoon Giardia lamblia Loraine Campanati, 1,2 Andreas Holloschi, 3 Helmut Troster, 4 Herbert Spring, 4 Wanderley de Souza, 2 and Luiz Henrique Monteiro-Leal 1 * 1 Universidade do Estado do Rio de Janeiro, Dept. de Histologia e Embriologia, Laborato ´ rio de Microscopia e Processamento de Imagens, Maracana ´ Rio de Janeiro, Brasil 2 Universidade Federal do Rio de Janeiro, Instituto de Biofı ´sica, Laborato ´ rio de Ultraestrutura Celular Hertha Meyer, Rio de Janeiro, Brasil 3 Institut fu ¨ r Molekularbiologie und Zellkulturtechnik, Fachhochschule Mannheim, Mannheim, Germany 4 Deutsches Krebsforschungzentrum, DKFZ- Biomedizinische Strukturforschung, Heidelberg, Germany Video-microscopy in combination with digital image processing was used to analyze dynamic processes associated to the life cycle of Giardia lamblia tropho- zoites. These parasites swim and attach to the epithelial cells, producing the disease known as Giardiasis. Giardia is a multiflagellar cell, presenting 4 pairs of flagella. With the use of analogue and digital tools, we observed that in cells attached to glass slides only 2 of the 4 pairs present active beating (wave propagation). The frequency observed was 17–18 Hz to the anterior and 8 –11 Hz to the ventral flagella. These data resulted from several hours of recording using both analogue video and high-speed digital camera. The caudal pair did not show active beating patterns and the same holds true for the posterior one. In this latter pair, oscillations were observed, but they were always associated to the transit of the wave produced by the ventral pair. The analysis performed with free moving cells showed that during its forward dislocation, Giardia lamblia presented either a lateral rocking or a complete rotational (tumbling) movement around its longi- tudinal axis. A dislocation of the caudal region of the cell both in the lateral and dorso-ventral direction was observed. This movement was completely indepen- dent from the flagellar beating and it is likely to be produced by a microtubular complex located in the caudal portion of the cell. The adhesion process of Giardia lamblia was also followed by video-microscopy and the data showed that the ventral disk had an active participation in this process. Cell Motil. Cytoskeleton 51:213–224, 2002. © 2002 Wiley-Liss, Inc. Key words: cell movements; image processing; fast-digital video system; analogue video-microscopy; protozoa The Supplemental Material referred to in this section can be found at http://www.interscience.wiley.com/jpages/0886-1544/suppmat/2002/ index.html Contract grant sponsor: Programa de Nu ´cleos de Excele ˆncia (PRONEX); Contract grant sponsor: Conselho Nacional de Pesquisa (CNPq); Contract grant sponsor: Conselho de Apoio a Pesquisa (CAPES); Contract grant sponsor: Fundac ¸a ˜o de Amparo a Pesquisa do Rio de Janeiro (FAPERJ); Contract grant number: SR2-UERJ; Contract grant sponsor: Deutscher Akademischer Austauschdienst (DAAD). *Correspondence to: Luiz Henrique Monteiro-Leal, Universidade do Estado do Rio de Janeiro, Dept. de Histologia e Embriologia, Labo- rato ´ rio de Microscopia e Processamento de Imagens, Av. Prof. Manoel de Abreu, 48 3 andar. Maracana ´ Rio de Janeiro, RJ-20550-170, Brasil. E-mail: mleal@uerj.br Received 20 September 2001; Accepted 28 December 2001 Published online in Wiley InterScience (www.interscience.wiley. com). DOI: 10.1002/cm.10026 Cell Motility and the Cytoskeleton 51:213–224 (2002) © 2002 Wiley-Liss, Inc.