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Open Access Research article

A quantitative view of the transcriptome of Schistosoma mansoni adult-worms using SAGE

Elida PB Ojopi1, Paulo SL Oliveira2, Diana N Nunes3, Apuã Paquola45, Ricardo DeMarco4, Sheila P Gregório14, Karina A Aires6, Carlos FM Menck5, Luciana CC Leite6, Sergio Verjovski-Almeida4 and Emmanuel Dias-Neto13*

Author Affiliations

1 Laboratório de Neurociências (LIM27), Instituto de Psiquiatria, Faculdade de Medicina da Universidade de São Paulo; R. Dr. Ovídio Pires de Campos, 785 – 3 rd floor, 05403-010, São Paulo, SP, Brazil

2 Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil

3 MD Anderson Cancer Center, University of Texas – 1515 Holcombe Blvd, Unit 1374, 77030 – Houston, TX, USA

4 Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil

5 Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, 05508-900, São Paulo, SP, Brazil

6 Centro de Biotecnologia, Instituto Butantan, 05503-900, São Paulo, SP, Brazil

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BMC Genomics 2007, 8:186  doi:10.1186/1471-2164-8-186

Published: 21 June 2007

Abstract

Background

Five species of the genus Schistosoma, a parasitic trematode flatworm, are causative agents of Schistosomiasis, a disease that is endemic in a large number of developing countries, affecting millions of patients around the world. By using SAGE (Serial Analysis of Gene Expression) we describe here the first large-scale quantitative analysis of the Schistosoma mansoni transcriptome, one of the most epidemiologically relevant species of this genus.

Results

After extracting mRNA from pooled male and female adult-worms, a SAGE library was constructed and sequenced, generating 68,238 tags that covered more than 6,000 genes expressed in this developmental stage. An analysis of the ordered tag-list shows the genes of F10 eggshell protein, pol-polyprotein, HSP86, 14-3-3 and a transcript yet to be identified to be the five top most abundant genes in pooled adult worms. Whereas only 8% of the 100 most abundant tags found in adult worms of S. mansoni could not be assigned to transcripts of this parasite, 46.9% of the total ditags could not be mapped, demonstrating that the 3 sequence of most of the rarest transcripts are still to be identified. Mapping of our SAGE tags to S. mansoni genes suggested the occurrence of alternative-polyadenylation in at least 13 gene transcripts. Most of these events seem to shorten the 3 UTR of the mRNAs, which may have consequences over their stability and regulation.

Conclusion

SAGE revealed the frequency of expression of the majority of the S. mansoni genes. Transcriptome data suggests that alternative polyadenylation is likely to be used in the control of mRNA stability in this organism. When transcriptome was compared with the proteomic data available, we observed a correlation of about 50%, suggesting that both transcriptional and post-transcriptional regulation are important for determining protein abundance in S. mansoni. The generation of SAGE tags from other life-cycle stages should contribute to reveal the dynamics of gene expression in this important parasite.