Analysis Of Plasmodium Falciparum Transcriptome Using RNA-sequence To Discover Novel Long Non-coding RNAs In Intraerythrocytic Development Stage

Malaria is a serious disease which is caused by infection of Plasmodium.Among various kinds of Plasmodium, plasmodium falciparum has the highest lethallty rate for those individuals who are affected. The life cycle of Plasmodium falciparum includes asexual reproductive period (exo-erythrocytic and intraerythrocytic stages) and sexual reproduction in mosquitoes (mosquitoes period). Asexual reproduction of Plasmodium falciparum in red blood cells, which starts with invasion of merozoites into red blood cells, undergos ring stage, early and late trophozoite stage, and ends with release of schizonts from red blood cells is the biological basis of malaria and the whole course of asexual reproduction. Therefore, it is quite meaningful to investigate the underlying mechanisms of asexual reproduction of Plasmodium falciparum in red blood cells.Long non-coding RNA (lncRNA) is arbitrarily defined as transcripts which is no less than 200bp in length and has no protein-coding capability, accounting for nearly 80% of all non-coding RNA. Piles of studies have shown that lncRNA can participate in various activities, including epigenetic modification, transcriptional and translational regulation, cell cycle control, cell differentiation, apoptosis and so on, through complicated mechanisms. It is revealed that numerous lncRNAs are transcripted from Plasmodium falciparum genome, however the the specific roles of these lncRNA in Plasmodium falciparum stay largely unknown.In order to discover novel lncRNA expressed and stage-specifical lncRNAs in different intraerythrocytic stages, we first synchronized in vitro cultured Plasmodium falciparum and performed transcipts sequencing of Plasmodium falciparum in different stages. For synchronization, we treated in vitro cultured Plasmodium falciparum at ring stage with sorbitol repeatedly. The synchronized protozoan were of several characteristics, such as highly synchronized, narrow variation ans high infection rate.Besides, we built 2 transcriptome libraries and performed Illumina/Solexa pair-ended sequencing, which corresponded to 2 different stages, namely ring stage and schizonts.We further analyzed the sequencing data of ring stage and schizont, including sequence alignment, sequence assembly and coding potential analysis, and indentified 55 novel lncRNAs candidates,13 of which were validated by RT-PCR.Our results provided foundation for further investigation of regulatory functions of lncRNAs in intraerythrocytic development of Plasmodium falciparum.