Consistent sense transcript and interspersed antisense transcript in var2csa gene. Histograms showing apparent absolute abundance of both sense and antisense transcript at the var2csa locus in CD36 (grey) and CSA (white) panned parasites. Different columns show the apparent absolute abundance for oligonucleotides at individual positions along the whole var2csa gene. Left panels show probes corresponding to sense transcript, right panels show probes corresponding to antisense transcripts. Separate histograms show data for ring, trophozoite and schizont stages. Standard deviation is shown. No truncated 5' transcript of the var2csa gene is apparent in CD36 panned parasites, suggesting regulation is not controlled by premature termination of transcription. In ring stages, where var2csa transcript is most abundant in CSA parasites, apparent absolute abundance is also increased for antisense transcripts throughout the gene. Unlike sense transcription, apparent absolute abundance for all antisense transcripts varies greatly between adjacent probes, perhaps indicative of multiple short antisense transcripts initiating throughout the locus. Abundance of sense and antisense transcript in both populations is also shown for a non-var locus, msp2, for which high antisense transcription has previously been measured . Both steady-state sense and antisense levels for the var2csa locus are comparable with those found at the msp2 locus.