Mitosis in Giardia lamblia: multiple modes of cytokinesis.
Mitosis in Giardia is poorly understood. Until today, it is still controversial whether Giardia divides with a mirror-image symmetry (ventral-ventral or dorsal-dorsal) or in a dorsal-ventral mode. Here, we report the different modes by which cytokinesis takes place in Giardia lamblia. To determine how Giardia divides, video microscopy, scanning electron microscopy, semi-thick sections and freeze-fracture replicas were analyzed by transmission electron microscopy. Between 12 and 15% of the cells cultivated for 24-48 h were found in the process of division. Three types of cytokinesis were found: (1) ventral-ventral, where the discs face each other; (2) dorsal-dorsal, where the discs are in opposite directions; and (3) ventral-dorsal. Giardia divides with mirror-image symmetry either in ventral-ventral or dorsal-dorsal modes. During ventral-ventral type of division, Giardia becomes detached and swims freely in the culture medium, whereas, in the other modes of division, the cells can be found either adhered or swimming.
Benchimol
Marlene
M
Universidade Santa Ursula, Rua Jornalista Orlando Dantas, 59, CEP 222-31-010 Botafogo, Rio de Janeiro, RJ, Brazil. marleneben@uol.com.br
D000818:Animals; D002448:Cell Adhesion; D048749:Cytokinesis; D005614:Freeze Fracturing; D016829:Giardia lamblia / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D018715:Microscopy, Video; D008867:Microtomy; D008938:Mitosis