Phosphorylation of actin-related protein 2 (Arp2) is required for normal development and cAMP chemotaxis in Dictyostelium.

Phosphorylation of the actin-related protein 2 (Arp2) subunit of the Arp2/3 complex on evolutionarily conserved threonine and tyrosine residues was recently identified and shown to be necessary for nucleating activity of the Arp2/3 complex and membrane protrusion of Drosophila cells. Here we use the Dictyostelium diploid system to replace the essential Arp2 protein with mutants that cannot be phosphorylated at Thr-235/6 and Tyr-200. We found that aggregation of the resulting mutant cells after starvation was substantially slowed with delayed early developmental gene expression and that chemotaxis toward a cAMP gradient was defective with loss of polarity and attenuated F-actin assembly.

Replacement of the essential Dictyostelium Arp2 gene by its Entamoeba homologue using parasexual genetics.

Background: Cell motility is an essential feature of the pathogenesis and morbidity of amoebiasis caused by Entamoeba histolytica. As motility depends on cytoskeletal organisation and regulation, a study of the molecular components involved is key to a better understanding of amoebic pathogenesis. However, little is known about the physiological roles, interactions and regulation of the proteins of the Entamoeba cytoskeleton.

Entamoeba histolytica cell movement: a central role for self-generated chemokines and chemorepellents.

Entamoeba histolytica cells, the cause of amoebic dysentery, are highly motile, and this motility is an essential feature of the pathogenesis and morbidity of amoebiasis. However, the control of E. histolytica motility within the gut and during invasion is poorly understood.

Use of PCR amplification of tRNA gene-linked short tandem repeats for genotyping Entamoeba histolytica.

We have developed a reliable method for PCR-based genotyping of Entamoeba histolytica based on variation in the numbers of short tandem repeats that are linked to tRNA genes in this species. Species-specific primer pairs were designed that differentiate E. histolytica from E.

Unique organisation of tRNA genes in Entamoeba histolytica.

The genome sequence of the protistan parasite Entamoeba histolytica HM-1:IMSS has been completed recently. Among the findings has been a unique organisation for the tRNA genes in this organism. Forty-two of the tRNA isoacceptor types are encoded in tandem arrays that vary in unit length from 490 to 1775 basepairs and contain from 1 to 5 tRNA genes.

Genotyping of Entamoeba species in South Africa: diversity, stability, and transmission patterns within families.

Using a recently described polymerase chain reaction-based DNA typing method for Entamoeba histolytica and E. dispar, we investigated the genetic diversity of these species in a geographically restricted region of South Africa. Patterns were stable over time in the same infection, and, with few exceptions, infected family members carried the same strain.

Simultaneous differentiation and typing of Entamoeba histolytica and Entamoeba dispar.

Sequences corresponding to some of the polymorphic loci previously reported from Entamoeba histolytica have been detected in Entamoeba dispar. Comparison of nucleotide sequences of two loci between E. dispar strain SAW760 and E.

The presence of antiamoebic constituents in psyllium husk.

The crude extract of psyllium husk (ispaghula) and its active constituent (petroleum fraction) caused varying degrees of growth inhibition in three different species of Entamoeba, i.e. Entamoeba histolytica, E.