Serial analysis of gene expression in Plasmodium falciparum reveals the global expression profile of erythrocytic stages and the presence of anti-sense transcripts in the malarial parasite
S. Patankar et al., Serial analysis of gene expression in Plasmodium falciparum reveals the global expression profile of erythrocytic stages and the presence of anti-sense transcripts in the malarial parasite, MOL BIOL CE, 12(10), 2001, pp. 3114-3125
Serial analysis of gene expression (SAGE) was applied to the malarial paras
ite Plasmodium falciparum to characterize the comprehensive transcriptional
profile of erythrocytic stages. A SAGE library of similar to 8335 tags rep
resenting 4866 different genes was generated from 3D7 strain parasites. Bas
ic local alignment search tool analysis of high abundance SAGE tags reveale
d that a majority (88%) corresponded to 3D7 sequence, and despite the low c
omplexity of the genome, 70% of these highly abundant tags matched unique l
oci. Characterization of these suggested the major metabolic pathways that
are used by the organism under normal culture conditions. Furthermore sever
al tags expressed at high abundance (30% of tags matching to unique loci of
the 3D7 genome) were derived from previously uncharacterized open reading
frames, demonstrating the use of SAGE in genome annotation. The open platfo
rm "profiling" nature of SAGE also lead to the important discovery of a nov
el transcriptional phenomenon in the malarial pathogen: a significant numbe
r of highly abundant tags that were derived from annotated genes (17%) corr
esponded to antisense transcripts. These SAGE data were validated by two in
dependent means, strand specific reverse transcription-polymerase chain rea
ction and Northern analysis, where antisense messages were detected in both
asexual and sexual stages. This finding has implications for transcription
al regulation of Plasmodium gene expression.