Giardia intestinalis is an ancient protist that causes the most commonly reported human diarrheal disease of parasitic origin worldwide. An intriguing feature of the Giardia cell is the presence of two morphologically similar nuclei, generally considered equivalent, in spite of the fact that their karyotypes are unknown. We found that within a single cell, the two nuclei differ both in the number and the size of chromosomes and that representatives of two major genetic groups of G. intestinalis possess different karyotypes. Odd chromosome numbers indicate aneuploidy of Giardia nuclei, and their stable occurrence is suggestive of a long-term asexuality. A semi-open type of Giardia mitosis excludes a chromosome interfusion between the nuclei. Differences in karyotype and DNA content, and cell cycle-dependent asynchrony are indicative of diversity of the two Giardia nuclei.

• MeSH
• aparát dělícího vřeténka MeSH
• buněčné jádro genetika   MeSH
• buněčný cyklus genetika   MeSH
• cytogenetické vyšetření MeSH
• Giardia cytologie   genetika   MeSH
• karyotypizace MeSH
• mitóza MeSH
• protozoální DNA genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protozoální DNA MeSH

Giardia intestinalis is a binucleated diplomonad possessing four pairs of flagella of distinct location and function. Its pathogenic potential depends on the integrity of a complex microtubular cytoskeleton that undergoes a profound but poorly understood reorganization during cell division. We examined the cell division of G. intestinalis with the aid of light and electron microscopy and immunofluorescence methods and present here new observations on the reorganization of the flagellar apparatus in the dividing Giardia. Our results demonstrated the presence of a flagellar maturation process during which the flagella migrate, assume different position, and transform to different flagellar types in progeny until their maturation is completed. For each newly assembled flagellum it takes three cell cycles to become mature. The mature flagellum of Giardia is the caudal one that possesses a privileged basal body at which the microtubules of the adhesive disk nucleate. In contrast to generally accepted assumption that each of the two diplomonad mastigonts develops separately, we found that they are developmentally linked, exchanging their cytoskeletal components at the early phase of mitosis. The presence of the flagellar maturation process in a metamonad protist Giardia suggests that the basal body or centriole maturation is a universal phenomenon that may represent one of the core processes in a eukaryotic cell.

• MeSH
• buněčné dělení fyziologie   MeSH
• flagella fyziologie   MeSH
• fluorescenční protilátková technika MeSH
• Giardia lamblia cytologie   ultrastruktura   MeSH
• konfokální mikroskopie MeSH
• transmisní elektronová mikroskopie MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH