Genome sequencing of the human parasite Schistosoma mansoni revealed an interesting gene superfamily, called micro-exon gene (meg), that encodes secreted MEG proteins. The genes are composed of short exons (3-81 base pairs) regularly interspersed with long introns (up to 5 kbp). This article recollects 35 S. mansoni specific meg genes that are distributed over 7 autosomes and one pair of sex chromosomes and that code for at least 87 verified MEG proteins. We used various bioinformatics tools to produce an optimal alignment and propose a phylogenetic analysis. This work highlighted intriguing conserved patterns/motifs in the sequences of the highly variable MEG proteins. Based on the analyses, we were able to classify the verified MEG proteins into two subfamilies and to hypothesize their duplication and colonization of all the chromosomes. Together with motif identification, we also proposed to revisit MEGs' common names and annotation in order to avoid duplication, to help the reproducibility of research results and to avoid possible misunderstandings.

Department of Biochemical Sciences Sapienza University of Rome 00185 Rome Italy

Department of Chemistry Faculty of Agrobiology Food and Natural Resources Czech University of Life Sciences 16500 Prague Czech Republic

Department of Zoology and Fisheries Center of Infectious Animal Diseases Czech University of Life Sciences 16500 Prague Czech Republic

UMR 5280 Institute of Analytical Sciences Université de Lyon CNRS Université Claude Bernard Lyon 1 69100 Villeurbanne France