Michael J. Bumbulis wrote:
>> Here's a question for someone in the know about Giardia.
> They have two nuclei, right? Well, do the two nuclei
> contain different sets of chromosomes? And during mitosis,
> do all the chromosomes mix or are the contents of each nucleus
> separated independently?
The most relevant publication on this topic is by Kabnick and Peattie
(below, with abstract). Giardia, like many protists, has a closed
mitosis (the nuclear membrane does not break down during division)
and so there CAN be no mixing as far as I can see. However, the nuclei
appear to be equivalent.
A. Kimo Morris wrote:
>no mitochondria, smooth er, golgi bodies or lysosomes have been
>detected in Giardia.
Not true at least as far as Golgi is concerned - it appears during
encystation - and possibly ER too (see the papers and review cited
C. Graham Clark, Ph.D.
Department of Medical Parasitology,
London School of Hygiene and Tropical Medicine,
Keppel Street, London WC1E 7HT, England, G.B.
e-mail: g.clark at lshtm.ac.uk
Kabnick KS, Peattie DA (1990) J Cell Sci 95: 353-360
In situ analyses reveal that the two nuclei of Giardia lamblia are
The protozoan parasite Giardia lamblia has the unusual morphology of
bearing two equal-sized nuclei. This organism probably represents the
earliest diverging lineage of eukaryotes, suggesting that its
biological tactics may be transitional. To begin to understand the
role played by the two equal-sized nuclei in this organism, and
perhaps the role this organism has played along the path to higher
eukaryotes, we have analyzed the structure and function of these two
nuclei. We show that the two nuclei are equivalent with respect to
the amount of DNA harbored in each nucleus, the presence of ribosomal
DNA sequences, and the transcriptional activity. We begin also to
address the question of how these bilaterally symmetrical ancestors
divide, by illustrating the mitotic plane of division.
McCaffery JM, Gillin FD (1994) Exp Parasitol 79: 220-235
Giardia lamblia: ultrastructural basis of protein transport during
growth and encystation.
Lujan HD, Marotta A, Mowatt MR, Sciaky N, Lippincott-Schwartz J,
Nash TE (1995) J Biol Chem 270: 4612-4618
Developmental induction of Golgi structure and function in the
primitive eukaryote Giardia lamblia.
Soltys BJ, Falah M, Gupta RS (1996) J Cell Sci 109: 1909-1917
Identification of endoplasmic reticulum in the primitive eukaryote
Giardia lamblia using cryoelectron microscopy and antibody to Bip.
Gillin FD, Reiner DS, McCaffery JM (1996) Annu Rev Microbiol 50:
Cell biology of the primitive eukaryote Giardia lamblia.