Figure 1

Periodical transcription of P. knowlesi genes during the IDC. Transcriptomes showing 4,165 PK genes of the ex-vivo (a) and two in-vitro samples (b,c) of the time course sampled at 4 hour intervals over 24–32 hours in culture. First column represents raw data during time courses; second column represents raw data after median centered normalization and third column represents equilibrium value centered data after smoothing by sine functions with H = 27 for ex vivo and H = 33 for in vitro. (d) Sine wave model and its equation. t is the time (hours) at each time points, and y(t) is the corresponding transcription levels at each time point. Equilibrium is the average level of one complete sine curve. Amplitude is visually represented as the vertical distance between the extrema of the sine curve and the equilibrium value. h is the period of one complete life cycle expressed in hours and phase is the fraction of one life cycle indicating time offset of an expression peak to the time point at one quarter of life cycle. (e) Prediction of duration for a complete cycle of ex vivo and in vivo samples (period time). 873 genes from ex vivo sample, 879 and 1117 genes from in vivo samples I and II significantly fit a sine curve (p value < 0.05 and amplitude above median) and were used to predict the period. The median period is 25.5 hours for ex vivo sample, and 33.5 hours for in vitro samples.