@article {49651, title = {Identification of Schistosoma mansoni microRNAs.}, journal = {BMC Genomics}, volume = {12}, year = {2011}, month = {2011}, pages = {47}, abstract = {

BACKGROUND: MicroRNAs (miRNAs) constitute a class of single-stranded RNAs which play a crucial role in regulating development and controlling gene expression by targeting mRNAs and triggering either translation repression or messenger RNA (mRNA) degradation. miRNAs are widespread in eukaryotes and to date over 14,000 miRNAs have been identified by computational and experimental approaches. Several miRNAs are highly conserved across species. In Schistosoma, the full set of miRNAs and their expression patterns during development remain poorly understood. Here we report on the development and implementation of a homology-based detection strategy to search for miRNA genes in Schistosoma mansoni. In addition, we report results on the experimental detection of miRNAs by means of cDNA cloning and sequencing of size-fractionated RNA samples.

RESULTS: Homology search using the high-throughput pipeline was performed with all known miRNAs in miRBase. A total of 6,211 mature miRNAs were used as reference sequences and 110 unique S. mansoni sequences were returned by BLASTn analysis. The existing mature miRNAs that produced these hits are reported, as well as the locations of the homologous sequences in the S. mansoni genome. All BLAST hits aligned with at least 95\% of the miRNA sequence, resulting in alignment lengths of 19-24 nt. Following several filtering steps, 15 potential miRNA candidates were identified using this approach. By sequencing small RNA cDNA libraries from adult worm pairs, we identified 211 novel miRNA candidates in the S. mansoni genome. Northern blot analysis was used to detect the expression of the 30 most frequent sequenced miRNAs and to compare the expression level of these miRNAs between the lung stage schistosomula and adult worm stages. Expression of 11 novel miRNAs was confirmed by northern blot analysis and some presented a stage-regulated expression pattern. Three miRNAs previously identified from S. japonicum were also present in S. mansoni.

CONCLUSION: Evidence for the presence of miRNAs in S. mansoni is presented. The number of miRNAs detected by homology-based computational methods in S. mansoni is limited due to the lack of close relatives in the miRNA repository. In spite of this, the computational approach described here can likely be applied to the identification of pre-miRNA hairpins in other organisms. Construction and analysis of a small RNA library led to the experimental identification of 14 novel miRNAs from S. mansoni through a combination of molecular cloning, DNA sequencing and expression studies. Our results significantly expand the set of known miRNAs in multicellular parasites and provide a basis for understanding the structural and functional evolution of miRNAs in these metazoan parasites.

}, keywords = {Animals, Computational Biology, Genome, Helminth, MicroRNAs, Schistosoma mansoni}, issn = {1471-2164}, doi = {10.1186/1471-2164-12-47}, author = {Sim{\~o}es, Mariana C and Lee, Jonathan and Djikeng, Appolinaire and Cerqueira, Gustavo C and Zerlotini, Adhemar and da Silva-Pereira, Rosiane A and Dalby, Andrew R and LoVerde, Philip and El-Sayed, Najib M and Oliveira, Guilherme} } @article {49646, title = {The genome of the blood fluke Schistosoma mansoni.}, journal = {Nature}, volume = {460}, year = {2009}, month = {2009 Jul 16}, pages = {352-8}, abstract = {

Schistosoma mansoni is responsible for the neglected tropical disease schistosomiasis that affects 210 million people in 76 countries. Here we present analysis of the 363 megabase nuclear genome of the blood fluke. It encodes at least 11,809 genes, with an unusual intron size distribution, and new families of micro-exon genes that undergo frequent alternative splicing. As the first sequenced flatworm, and a representative of the Lophotrochozoa, it offers insights into early events in the evolution of the animals, including the development of a body pattern with bilateral symmetry, and the development of tissues into organs. Our analysis has been informed by the need to find new drug targets. The deficits in lipid metabolism that make schistosomes dependent on the host are revealed, and the identification of membrane receptors, ion channels and more than 300 proteases provide new insights into the biology of the life cycle and new targets. Bioinformatics approaches have identified metabolic chokepoints, and a chemogenomic screen has pinpointed schistosome proteins for which existing drugs may be active. The information generated provides an invaluable resource for the research community to develop much needed new control tools for the treatment and eradication of this important and neglected disease.

}, keywords = {Animals, Biological Evolution, Exons, Genes, Helminth, Genome, Helminth, Host-Parasite Interactions, Introns, Molecular Sequence Data, Physical Chromosome Mapping, Schistosoma mansoni, Schistosomiasis mansoni}, issn = {1476-4687}, doi = {10.1038/nature08160}, author = {Berriman, Matthew and Haas, Brian J and LoVerde, Philip T and Wilson, R Alan and Dillon, Gary P and Cerqueira, Gustavo C and Mashiyama, Susan T and Al-Lazikani, Bissan and Andrade, Luiza F and Ashton, Peter D and Aslett, Martin A and Bartholomeu, Daniella C and Blandin, Ga{\"e}lle and Caffrey, Conor R and Coghlan, Avril and Coulson, Richard and Day, Tim A and Delcher, Art and DeMarco, Ricardo and Djikeng, Appolinaire and Eyre, Tina and Gamble, John A and Ghedin, Elodie and Gu, Yong and Hertz-Fowler, Christiane and Hirai, Hirohisha and Hirai, Yuriko and Houston, Robin and Ivens, Alasdair and Johnston, David A and Lacerda, Daniela and Macedo, Camila D and McVeigh, Paul and Ning, Zemin and Oliveira, Guilherme and Overington, John P and Parkhill, Julian and Pertea, Mihaela and Pierce, Raymond J and Protasio, Anna V and Quail, Michael A and Rajandream, Marie-Ad{\`e}le and Rogers, Jane and Sajid, Mohammed and Salzberg, Steven L and Stanke, Mario and Tivey, Adrian R and White, Owen and Williams, David L and Wortman, Jennifer and Wu, Wenjie and Zamanian, Mostafa and Zerlotini, Adhemar and Fraser-Liggett, Claire M and Barrell, Barclay G and El-Sayed, Najib M} } @article {49643, title = {Schistosoma mansoni: Microarray analysis of gene expression induced by host sex.}, journal = {Exp Parasitol}, volume = {120}, year = {2008}, month = {2008 Dec}, pages = {357-63}, abstract = {

Schistosoma mansoni is a digenetic trematode and a human parasite responsible for high social and economic impact. Although some authors have studied the effect of host hormones on parasites, not much is known about the effects of host sex on gene expression in Schistosomes. In order to study gene transcripts associated with the host sex, we compared the gene expression profiles of both male and female unisexual adult S. mansoni parasites raised on either male or female hosts, using DNA microarrays. Our results show that host sex caused differential expression of at least 11 genes in female parasites and of 134 in male parasites. Of the differentially expressed genes in female worms, 10 were preferentially expressed in female worms from male mice, while of the 134 differentially expressed genes in male parasites, 79 (59\%) were preferentially expressed in worms from female mice. Further investigation of the role of each of those genes will help understand better their importance in the pathogenesis of Schistosomiasis.

}, keywords = {Animals, Biomphalaria, Female, Gene expression, Host-Parasite Interactions, Male, Mice, Oligonucleotide Array Sequence Analysis, Reverse Transcriptase Polymerase Chain Reaction, RNA, Helminth, Schistosoma mansoni, Schistosomiasis mansoni, Sex Factors}, issn = {1090-2449}, doi = {10.1016/j.exppara.2008.09.005}, author = {Waisberg, M and Lobo, F P and Cerqueira, G C and Passos, L K J and Carvalho, O S and El-Sayed, N M and Franco, G R} } @article {38481, title = {Schistosoma mansoni genome: Closing in on a final gene set}, journal = {Experimental ParasitologyExperimental Parasitology}, volume = {117}, year = {2007}, type = {16/j.exppara.2007.06.005}, abstract = {The Schistosoma mansoni genome sequencing consortium has recently released the latest versions of the genome assembly as well as an automated preliminary gene structure annotation. The combined datasets constitute a vast resource for researchers to exploit in a variety of post-genomic studies with an emphasis of transcriptomic and proteomic tools. Here we present an innovative method used for combining diverse sources of evidence including ab initio gene predictions, protein and transcript sequence homologies, and cross-genome sequence homologies between S. mansoni and Schistosoma japonicum to define a comprehensive list of protein-coding genes.}, keywords = {Annotation, Gene finding, Genome, Schistosoma mansoni}, isbn = {0014-4894}, author = {Haas, Brian J. and Berriman, Matthew and Hirai, Hirohisa and Cerqueira, Gustavo G. and LoVerde, Philip T. and Najib M. El-Sayed} } @article {38479, title = {Schistosoma mansoni (Platyhelminthes, Trematoda) nuclear receptors: Sixteen new members and a novel subfamily}, journal = {GeneGene}, volume = {366}, year = {2006}, type = {16/j.gene.2005.09.013}, abstract = {Nuclear receptors (NRs) are important transcriptional modulators in metazoans. Sixteen new NRs were identified in the Platyhelminth trematode, Schistosoma mansoni. Three were found to possess novel tandem DNA-binding domains that identify a new subfamily of NR. Two NRs are homologues of the thyroid hormone receptor that previously were thought to be restricted to chordates. This study brings the total number of identified NR in S. mansoni to 21. Phylogenetic and comparative genomic analyses demonstrate that S. mansoni NRs share an evolutionary lineage with that of arthropods and vertebrates. Phylogenic analysis shows that more than half of the S. mansoni nuclear receptors evolved from a second gene duplication. As the second gene duplication of NRs was thought to be specific to vertebrates, our data challenge the current theory of NR evolution.}, keywords = {Nuclear receptors, Schistosoma mansoni}, isbn = {0378-1119}, author = {Wu, Wenjie and Niles, Edward G. and Najib M. El-Sayed and Berriman, Matthew and LoVerde, Philip T.} } @article {38480, title = {Schistosoma mansoni genome project: an update}, journal = {Parasitology InternationalParasitology International}, volume = {53}, year = {2004}, type = {16/j.parint.2004.01.009}, abstract = {A schistosome genome project was initiated by the World Health Organization in 1994 with the notion that the best prospects for identifying new targets for drugs, vaccines, and diagnostic development lie in schistosome gene discovery, development of chromosome maps, whole genome sequencing and genome analysis. Schistosoma mansoni has a haploid genome of 270 Mb contained on 8 pairs of chromosomes. It is estimated that the S. mansoni genome contains between 15~000 and 25~000 genes. There are approximately 16~689 ESTs obtained from diverse libraries representing different developmental stages of S. mansoni, deposited in the NCBI EST database. More than half of the deposited sequences correspond to genes of unknown function. Approximately 40-50\% of the sequences form unique clusters, suggesting that approximately 20-25\% of the total schistosome genes have been discovered. Efforts to develop low resolution chromosome maps are in progress. There is a genome sequencing program underway that will provide 3X sequence coverage of the S. mansoni genome that will result in approximately 95\% gene discovery. The genomics era has provided the resources to usher in the era of functional genomics that will involve microarrays to focus on specific metabolic pathways, proteomics to identify relevant proteins and protein-protein interactions to understand critical parasite pathways. Functional genomics is expected to accelerate the development of control and treatment strategies for schistosomiasis.}, keywords = {Chromosome mapping, Gene discovery, Genomics, Schistosoma mansoni}, isbn = {1383-5769}, author = {LoVerde, Philip T. and Hirai, Hirohisa and Merrick, Joseph M. and Lee, Norman H. and Najib M. El-Sayed} }