Mutant/mutation
The mutant expresses a C-terminal GFP-tagged version of PP1

Protein (function)
PP1 is a serine/threonine protein phosphatase

Phenotype
A diffuse cytoplasmic and nuclear distribution of PP1-GFP, together with a distinct single focus of concentrated PP1-GFP in the nucleus of early trophozoite stage,representing the early S-phase of the cell cycle when DNA synthesis starts. As schizogony proceeds, the diffuse distribution of PP1-GFP remained; however, in early schizonts each cell displayed two distinct PP1-GFP foci in close association with the stained nuclear DNA. These pairs of PP1-GFP foci became clearer during the middle and late schizont stages but following merozoite maturation and egress the intensity of the foci diminished.

PP1-GFP by live-cell imaging was examined over a 15-minute period following male gametocyte activation. Before activation (0 min), PP1-GFP was detected with a diffuse location throughout gametocytes. At one minute post-activation, PP1-GFP accumulated at one end of the nucleus at a single focal point. After 2-3 min two distinct foci were observed on one side of the nucleus, concurrent with the first round of chromosome replication/segregation. Subsequently, four and eight  PP1-GFP foci were observed at 6 to 8 min and 8 to 12 min post-activation, respectively, corresponding to the second and third rounds of chromosome replication/segregation. These discrete PP1-GFP foci dispersed prior to karyokinesis and exflagellation of the mature male gamete 15 min post-activation, leaving residual protein remaining diffusely distributed throughout the remnant gametocyte and flagellum.

PP1-GFP was expressed in both male and female gametes with a diffuse distribution, along with a single focus of intense fluorescence at one end (potentially the basal body) of each male gamete. Initially, the zygote also had a diffuse PP1 distribution, but after two hours (stage I) an enriched focus developed at the periphery of the zygote, marking the point that subsequently protruded out from the cell body and developed into the apical end of the ookinete. A strong PP1-GFP fluorescence signal remained at this apical end throughout ookinete differentiation. In addition, PP1-GFP was enriched in the nucleus at four discrete foci in mature ookinetes.

Multiple foci of PP1GFP along with diffused localization during oocyst development.

By ultrastructure analysis of PP1PTD evidence is presented that gametocytes show defects in nuclear pole and axoneme assembly

See Additional information for analysis expression of PP1-GFP in mutants expressing  PP1-GFP and mCherry-tagged NDC80 or  PP1-GFP and mCherry-tagged Myosin A. These mutants were obtained by crossing PP1-GFP mutant with mutant RMgm-4844 and mutant RMgm-4669 respectively.
 
See RMgm-5003 for a mutant with 'conditional knockdown' of PP1 expression in gametocytes (with the phenotype of reduced numbers of exflagellation (male gamete formation) and strongly reduced ookinete formation. No oocyst formation).

Additional information
Analysis of expression of PP1-GFP in mutants expressing PP1-GFP and the mCherry-tagged kinetochore marker NDC80 or PP1-GFP and inner membrane complex (IMC)-associated mCherry-tagged Myosin A, showed the following:
- co-localisation of PP1-GFP and NDC80-mCherry foci close to the DNA of the nucleus  through blood stage development, and especially during late schizogony and segmentation; whereas the PP1-GFP foci at the outer periphery of the cell showed a partial co-location with MyoA-mCherry, and only during mid- to late schizogony.
- discrete PP1-GFP foci colocalized with NDC80-mCherry at different stages of male gametogony, including when up to eight kinetochores were visible, but PP1-GFP was not associated with the arc-like bridges of NDC80-mCherry representing the spindle at 2 min and 4 to 5 min post activation, suggesting that PP1-GFP is only increased at the kinetochore during initiation and termination of spindle division.
- PP1-GFP was enriched in the nucleus at four discrete foci in mature ookinetes. Analysis of the parasite line expressing both PP1-GFP and NDC80-mCherry showed that these four foci correspond to the kinetochores of meiotic development in the ookinete.
- Dual colour imaging showed a partial co-localisation of nuclear PP1-GFP and NDC80-mCherry foci throughout oocyst development and in sporozoites, suggesting that PP1-GFP is diffusely distributed during oocyst development but also recruited to kinetochores, as highlighted by multiple nuclear foci during oocyst development.

From the Abstract:
'Using real-time live-cell and ultrastructural imaging, conditional gene knockdown, RNA-seq and proteomic approaches, we show that Plasmodium PP1 is implicated in both mitotic exit and, potentially, establishing cell polarity during zygote development in the mosquito midgut'.

Other mutants