Biology of Giardia lamblia

Authors
Citation
Rd. Adam, Biology of Giardia lamblia, CLIN MICROB, 14(3), 2001, pp. 447
Citations number
363
Language
INGLESE
art.tipo
Review
Categorie Soggetti
Microbiology
Journal title
CLINICAL MICROBIOLOGY REVIEWS
ISSN journal
0893-8512 → ACNP
Volume
14
Issue
3
Year of publication
2001
Database
ISI
SICI code
0893-8512(200107)14:3<447:BOGL>2.0.ZU;2-R
Abstract
Giardia lamblia is a common cause of diarrhea in humans and other mammals t hroughout the world. It can be distinguished front other Giardia species by light ol electron microscopy. The two major genotypes of G. lamblia that i nfect humans are so different generically and biologically that they may wa rrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane syst em with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes mol e extensive in encysting organisms. The primit ive nature of the organelles and metabolism as well as small-subunit rRNA p hylogeny, has led to the proposal that Giardia spp. are among the most prim itive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size o f approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5' and 3' untranslated regions and promoter regions that ale near th e initiation codon. Trophozoites exhibit antigenic variation of an extensiv e repertoire of cysteine-lich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism.