In this study, 16 genes AZD6244 clinical trial (six of these contain predicted
signal sequences) that showed significant differences in hybridization intensities between two parent strains were found to co-segregate with their respective eQTLs in F1 progeny. These data support a cis-acting model of regulation for the strain-specific expression of these genes (38). The gene coverage constraint of the cDNA arrays is surmounted by genome-wide oligonucleotide microarrays. With the completion of the ME49 reference genome, custom oligonucleotide arrays (ToxoGeneChip) have been designed to allow for whole-genome expression profiling and genotyping (39). The array contains at least 11 perfect match probes for each of the approximately 8000 predicted genes providing coverage for most of the genes in the Toxoplasma genome (39). Probes for 260 human and mouse genes that are mostly involved in immune response have also been featured on this array to allow for simultaneous analysis of parasite and host genes that modulate infections. Novel gene discovery and SNP analysis are some new applications that are possible with this microarray. Using these new arrays, Bahl et al. (39) have shown
LY2109761 that nearly half of the predicted genes (3986) are expressed in tachyzoites. In another study, these arrays have been used to profile bradyzoite gene expression among the three main clonotypes of Toxoplasma (40) and provided confirmation for previously suggested strain-dependent differential expression of bradyzoite genes including B-NTPase (41). It also showed that the type I-GT1 strain retains a tachyzoite expression profile under bradyzoite conditions consistent with their decreased tendency to differentiate (39,40). The correlation between parasite replication rate and pathogenesis has been well documented (15,42). However, Selleckchem Paclitaxel the cell division process and its regulatory mechanisms are not entirely understood in T. gondii. A lot of effort has therefore been spent trying to understand the molecular controls and mechanisms that underlie the unique modes of division in the different developmental stages. A significant portion of our current knowledge on the subject
has resulted from forward genetic studies using temperature-sensitive cell cycle mutants (42–46). Identification of essential genes in such conditional mutants has been greatly helped by the fact that the tachyzoite stage, which is the most genetically amenable stage, is haploid and is able to replicate indefinitely in cell culture. Genetic complementation using T. gondii genomic cosmid and cDNA libraries has proven extremely useful for the identification of genes underlying conditional-mutant phenotypes (42,43,47,48). Extensive screening of temperature-sensitive mutants has revealed a complex cell cycle regulatory mechanism involving checkpoints (G1, G1/S, M) and spatial and structural coordination of mitotic events (42,43) that is in many ways analogous to those observed in higher eukaryotes (44).