Mutant/mutation
The mutant lacks expression of POS8 (putative ookinete surface-associated protein, 9)

Protein (function)
The protein was identified in a genome-wide screen of target genes of AP2-O by chromatin immunoprecipitation-sequencing.

Phenotype
The successful knock-out of pos8 indicates it has no essential role during blood stage development/multiplication. The mutant produced normal numbers of ookinetes. More than 20-fold reduction in oocyst numbers. The size of parasite oocysts was clearly smaller than that of the wild-type parasite oocysts [as observed by phase contrast microscopy at 14 days post-infection (dpi). To identify the step in which they decreased in number, parasites were generated that constitutively expressed GFP from these disruptant populations and  the oocysts shortly after ookinete invasion of the midgut at 2 dpi were counted. The number of oocysts was already approximately 10-fold smaller than that of wild-type parasites.We further measured oocyst diameters by epifluorescence microscopy at 14 dpi. The average oocyst diameter was approximately 60% of that of the wild-type oocysts, suggesting that oocyst development was impaired by this disruption.

Additional information

Other mutants
RMgm-1300: A mutant expressing a GFP-tagged version of POS8