IFA location of MSP1₁₉, CRT and new full length MSP1 during schizogony.

<p>Mature parasites at different stages of nuclear division were compared. Each row in panels A and B shows an identical field from 1% formaldehyde-fixed thin smears of late-stages parasites at the 1-, 2-, 4-, and 8-nuclei stage. Panels A1 and B1 show anti-MSP1₁₉(rabbit) and rabbit anti-CRT(rabbit) antibody labeling respectively (the secondary antibody was Alexa Fluor 488-conjugated anti-rabbit IgG antibody (green). Panels A2 and B2 show the same fields merged with the corresponding DAPI stained nucleus images (blue). Panels A3 and B3 show the same fields visualized by light microscopy - note the pigment is clearly visible. Rabbit-anti-MSP1₁₉ antibody only detects MSP1₁₉ associated with the food vacuole until the two-nuclei stage. Once new full length MSP1 is synthesized and transported to the parasite's plasma membrane the presence of MSP1₁₉ from the previous cycle is now obscured. In contrast, rabbit-anti-CRT antiobody is clearly detectable throughout parasite maturation and is associated with the food vacuole. Panel C, rows (a) and (b), shows that MSP1 and CRT are associated with the residual body that is released upon schizont rupture. Thin smears made at the time of schizont rupture were probed consecutively with mAb 1E1 and rabbit anti-CRT antibodies. These antibodies were detected using Alexa Fluor 488-conjugated anti-mouse IgG, and Alexa Fluor 594-conjugated anti-rabbit IgG, respectively (columns 1 and 2). Column 4 shows the bright field microscopy images of the same field and clearly indicate the presence of malarial pigment. Column 5 shows the absence of nuclear material in the residual bodies, as confirmed by the lack of DAPI staining. Column 3 shows the merged images from columns 1, 2 and 5 - both CRT and MSP1₁₉, or MSP1, which cannot be distinguished by the antibody, are associated with the released pigment in the residual body.