R invasion and do not start nuclear replication. Remarkably, a relatively large proportion of the replicating Dp52 p36 parasites, 45 (60.7 ) resided inside the nucleus of hepatocytes, compared to 1.25 (60.35 ) of intranuclear wildtype parasites (p,0.01) at 24 hours post invasion (Fig. 1a, Table S1). The absolute number of intranuclear mutant parasites PHCCC site matched the number of wildtype parasites. For both wildtype and mutant parasites, there was a slight decrease in the percentage of intranuclear developing parasites during the course of parasite maturation. At any time point, however, while the absolute number remained the same, the percentage of intranuclear mutant parasites was significantly higher than the percentage of intranuclear wildtype parasites (p,0.05) (Fig. 1a). Intranuclear developing P. berghei wildtype and Dp52 p36 parasites were negative for UIS-4 peripheral staining, a marker for the presence of a PVM (Fig. 1b) and did not express MSP-1 at 52 hours post infection, as depicted by an intranuclear Dp52 p36 parasite (Fig. 1c). At time points up to 72 hours post infection, these parasites remained negative (data not shown) indicating that the absence of MSP1 staining is not the results of a delay in maturation period. Based on MSP-1 expression, intranuclear parasites are unlikely the cause of Dp52 p36 parasite breakthrough in mice.TEM Analysis of Infected Huh-7 CellsFor ultrathin-section transmission electron microscopy, 26105 wt and 56105 p52/p36-deficient sporozoites were used to infect 3.56105 sub-confluent Huh-7 cells, seeded the day prior in 35 mm petridishes. Sporozoites were centrifuged for 10 minutes at 18006G and 32 hours post infection cells were fixed in 2.5 glutaraldehyde (Electron Microscopy Sciences) in 0.1 M sodium cacodylate buffer (pH 7.4) for 1 h at room temperature and subsequently washed three times for 10 minutes in 0.1 M sodium cacodylate buffer and then post-fixed for 1 h in 1 osmium tetroxide (Electron Microscopy Sciences, Gibbstown, NY) in sodium cacodylate buffer at room temperature. Samples were washed three times 20 minutes in 0.1 M sodium cacodylate buffer and subsequently dehydrated in a graded series (10-50-70-96100 ) of ethanol. Cells were resin infiltrated in a 100 ethanol/ EPON (Sigma) mixture (2:1) for 3 hours and subsequently in a 100 ethanol/EPON mixture (1:1) for 5 hours and subsequently in pure EPON overnight. Beem capsules were placed onto the cells (-)-Indolactam V web perpendicular, filled with EPON, and polymerized overnight at 60uC. Ultrathin (50?00 nm) sections were cut parallel to the cell surface using an Ultracut ultramicrotome (Leica, Germany) and contrasted with 2 uranyl acetate 1317923 and lead citrate before examination with a JEOL 1010 microscope under 60 kV.Cytosolic Dp52 p36 Parasites can Produce Mature Merozoites in the Absence of an Apparent PVMMore than half of the replicating Dp52 p36 parasites resided in the cytosol of Huh-7 hepatocytes (Fig. 1a) expressing MSP-1 and transforming into mature merozoites from 52 hours post invasion onwards. These cytosolic Dp52 p36 parasites did not show the typical round shape of wildtype parasites, but were instead characterized by an irregular morphology (Fig. 2a, Fig S1). Individual merosomes were clearly visible budding of from the infected hepatocyte (Fig S1 right box). Replicating cytosolic Dp52 pCytosolic Dp52 p36 P. berghei Lack Apparent PVMFigure 1. Intranuclear development of Dp52 p36 P. berghei parasites. A) Pie diagrams of intranuclear and cytoso.R invasion and do not start nuclear replication. Remarkably, a relatively large proportion of the replicating Dp52 p36 parasites, 45 (60.7 ) resided inside the nucleus of hepatocytes, compared to 1.25 (60.35 ) of intranuclear wildtype parasites (p,0.01) at 24 hours post invasion (Fig. 1a, Table S1). The absolute number of intranuclear mutant parasites matched the number of wildtype parasites. For both wildtype and mutant parasites, there was a slight decrease in the percentage of intranuclear developing parasites during the course of parasite maturation. At any time point, however, while the absolute number remained the same, the percentage of intranuclear mutant parasites was significantly higher than the percentage of intranuclear wildtype parasites (p,0.05) (Fig. 1a). Intranuclear developing P. berghei wildtype and Dp52 p36 parasites were negative for UIS-4 peripheral staining, a marker for the presence of a PVM (Fig. 1b) and did not express MSP-1 at 52 hours post infection, as depicted by an intranuclear Dp52 p36 parasite (Fig. 1c). At time points up to 72 hours post infection, these parasites remained negative (data not shown) indicating that the absence of MSP1 staining is not the results of a delay in maturation period. Based on MSP-1 expression, intranuclear parasites are unlikely the cause of Dp52 p36 parasite breakthrough in mice.TEM Analysis of Infected Huh-7 CellsFor ultrathin-section transmission electron microscopy, 26105 wt and 56105 p52/p36-deficient sporozoites were used to infect 3.56105 sub-confluent Huh-7 cells, seeded the day prior in 35 mm petridishes. Sporozoites were centrifuged for 10 minutes at 18006G and 32 hours post infection cells were fixed in 2.5 glutaraldehyde (Electron Microscopy Sciences) in 0.1 M sodium cacodylate buffer (pH 7.4) for 1 h at room temperature and subsequently washed three times for 10 minutes in 0.1 M sodium cacodylate buffer and then post-fixed for 1 h in 1 osmium tetroxide (Electron Microscopy Sciences, Gibbstown, NY) in sodium cacodylate buffer at room temperature. Samples were washed three times 20 minutes in 0.1 M sodium cacodylate buffer and subsequently dehydrated in a graded series (10-50-70-96100 ) of ethanol. Cells were resin infiltrated in a 100 ethanol/ EPON (Sigma) mixture (2:1) for 3 hours and subsequently in a 100 ethanol/EPON mixture (1:1) for 5 hours and subsequently in pure EPON overnight. Beem capsules were placed onto the cells perpendicular, filled with EPON, and polymerized overnight at 60uC. Ultrathin (50?00 nm) sections were cut parallel to the cell surface using an Ultracut ultramicrotome (Leica, Germany) and contrasted with 2 uranyl acetate 1317923 and lead citrate before examination with a JEOL 1010 microscope under 60 kV.Cytosolic Dp52 p36 Parasites can Produce Mature Merozoites in the Absence of an Apparent PVMMore than half of the replicating Dp52 p36 parasites resided in the cytosol of Huh-7 hepatocytes (Fig. 1a) expressing MSP-1 and transforming into mature merozoites from 52 hours post invasion onwards. These cytosolic Dp52 p36 parasites did not show the typical round shape of wildtype parasites, but were instead characterized by an irregular morphology (Fig. 2a, Fig S1). Individual merosomes were clearly visible budding of from the infected hepatocyte (Fig S1 right box). Replicating cytosolic Dp52 pCytosolic Dp52 p36 P. berghei Lack Apparent PVMFigure 1. Intranuclear development of Dp52 p36 P. berghei parasites. A) Pie diagrams of intranuclear and cytoso.
