Mutant/mutation
The mutant lacks expression of UAP and expresses mCherry and GFP under constitutive promoters.

Protein (function)
The gene has been selected based on a predicted role in mosquito- or liver-stage development in a high throughput screen where more than 1300 barcoded P. berghei mutants were followed through the complete life cycle.

Phenotype
No salivary gland sporozoites.
Ookinetes and oocysts were produced in normal numbers  but oocysts gradually disappeared over the course of development and failed to give rise to sporozoites.
See below for a role during liver stage development.

Additional information
The gene has been selected based on a predicted role in mosquito- or liver-stage development in a high throughput screen where more than 1300 barcoded P. berghei mutants (PlasmoGem) were followed through the complete life cycle.
Barcodes were quantified in blood stages (B1), midgut oocysts (MG), salivary gland sporozoites (SG) and in blood stages after intravenous infection of mice with sporozoites (B2).
In the different life cycle transitions, barcode quantification was described as not-reduced, reduced or no power. For this gene:
B1-MG: not reduced
MG-SG: no power
SG-B2: reduced (-8.1)

Cross-fertilization between different mutants in the mosquito midgut limits the power of the screen to reveal gene functions during the subsequent diploid and polyploid stages (i.e. zygotes, ookinetes and oocysts). For instance, knock-out mutants in which only one sex is sterile, can transmit their barcodes to the oocyst by inheritance through the fertile sex. As a result, reductions in barcode abundance for these sex-specific knock-out mutants often did not reach significance at the B1-MG conversion. Known gene functions in the diploid/polyploid ookinete were also generally not recapitulated in the screen, presumably due to heterozygous rescue as a result of cross-fertilization. While these observations highlight the need for future screens to be designed specifically to reveal sexual and mosquito stage phenotypes, they also rationalize how knock-out alleles of genes functioning in fertility or ookinete/oocyst development can be transmitted to salivary gland sporozoites to reveal additional gene functions after sporozoite transmission to the vertebrate host.

Liver stage phenotype:
In the paper a method is described where they cross-fertilize wild type parasites with a mutant lacking UAP. The crossing rescues the knock-out phenotype in the mosquito (see above for explanation). Since the knock-out mutant expresses fluorescent markers and a pyrimethamine resistance marker it is possible to analyse the fluorescent haploid knock-out sporozoites during development in the liver and to determine the prepatent period of the knock-out mutant. It was found that mice intravenously infected with defined numbers of mutant sporozoites did not develop blood infections or with a prolonged prepatent period (8.4 days; 5-11).

Other mutants