Calcium is a universal second messenger molecule which plays a significant role in several biological processes. Presence of calcium sensors (calmodulins) and calcium-dependent protein kinases in Plasmodium species suggests an important role of calcium-dependent signaling pathways in the regulation of cellular processes in the malaria parasites. Evidence for the transcriptional response of Plasmodium falciparum asexual blood stages to the well-known calcium ionophore ionomycin has been presented here.
Overall design: P. falciparum 3D7 strain was cultured as described by Bozdech Z, Llinas M, Pulliam BL, Wong ED, Zhu J, DeRisi JL: The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum. PLoS Biol 2003, 1(1):E5. Calcium ionophore treatment was done as follows. Parasites at schizont stage were treated with 5 μM of calcium ionophore, ionomycin for 30 minutes, 1 hour, 2 hours, 4 hours and 6 hours. Total RNA from each of the time points was isolated and aminoallyl-cDNA was synthesized using reverse transcriptase system (Fermentas). cDNA made from the treated parasites were labeled with Cy5 (GE-Amersham). A reference pool was made by mixing equal amount of cDNA from the parasites collected at 6 hours interval throughout the 48 hours life cycle and was labeled with Cy3 (GE-Amersham). The samples were then hybridized on a spotted cDNA chip platform comprising 10166 MOEs representing 5363 coding sequences as described in Hu G, Cabrera A, Kono M, Mok S, Chaal BK, Haase S, Engelberg K, Cheemadan S, Spielmann T, Preiser PR, Gilberger TW, Bozdech Z: Transcriptional profiling of growth perturbations of the human malaria parasite Plasmodium falciparum. Nat Biotechnol, 2009. 28(1): p. 91-8. The data was normalized and filtered with the condition, signal intensity>background intensity + 2 SD of background intensity) using NOMAD.
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