Table 1.
Growth Characteristics of Blood Stages of Wild-Type and Δpm4 Parasites
| Start of schizogony |
First mature schizonts |
Merozoites per schizont |
|||||
|---|---|---|---|---|---|---|---|
| Line | In vivo multiplication rate* | Hours† | Schizonts (%)† | Hours‡ | Merozoites (%)‡ | Gate P2§ | Gate P3§ |
| Wild-type | 10 (0) | 18 (0) | 14 (3) | ND | ND | 13.1 (0.5) | 16.7 (0.5) |
| Δpm4 (688cl2) | 5.8 (0.5) | 21 (0) | 15 (3) | ND | ND | 13.2 (0.5) | 17.3 (0.6) |
| wt+ (1037cl1) | 10 (0) | 19 (0) | 14 (2) | 23 (0) | 12 (2) | 12.7 (0.4) | 16.6 (0.4) |
| Δpm4+ (1092cl4) | 7.0 (0.8) | 22 (0) | 15 (3) | 26 (1) | 11 (3) | 12.7 (0.3) | 16.1 (0.2) |
Data are mean (SD).
ND, no data.
The multiplication rate per 24 hours is determined in mice infected with a single parasite.
The start of schizogony (S/M phase) was determined by flow cytometry (Supplemental Figure S4, see http://ajp.amjpathol.org) and is demonstrated by the presence of polyploid schizonts (cells with 3-16N present in P5 in Supplemental Figure S4, see http://ajp.amjpathol.org). The start of schizogony is defined as the time point (hours postinvasion) at which the percentage of cells with more than the haploid DNA content (% of schizonts; cells in gate P5 in Supplemental Figure S4, see http://ajp.amjpathol.org) had increased more than 5% compared with the averages of the previous time points. The percentage of schizonts in gate P5 is the mean of at least three measurements. Multiple measurements of blood samples of the haploid stages (rings and trophozoites) have shown that the percentage of cells in gate P5 has less than 2% variation.
The time point at which schizonts are mature is determined by flow cytometry as shown in Supplemental Figure S4 (see http://ajp.amjpathol.org) and is demonstrated by the presence of the haploid, free merozoites (gate P6 in Supplemental Figure S4, see http://ajp.amjpathol.org). This time point is defined as the time point (hours postinfection) at which the percentage of merozoites in P6 had increased more than 5% compared with the previous time point. The percentage of merozoites in gate P6 is the mean of at least three measurements.
The number of merozoites per schizonts is determined in cultured parasites by flow cytometry as described in Materials and Methods and shown in Supplemental Figure S3 (see http://ajp.amjpathol.org). The mean number of merozoites is shown for schizonts present in gate P2 and in gate P3 (Supplemental Figure S3, see http://ajp.amjpathol.org).