Cestode strobilation: prediction of developmental genes and pathways

Abstract

Background: Cestoda is a class of endoparasitic worms in the flatworm phylum (Platyhelminthes). During the course of their evolution cestodes have evolved some interesting aspects, such as their increased reproductive capacity. In this sense, they have serial repetition of their reproductive organs in the adult stage, which is often associated with external segmentation in a developmental process called strobilation. However, the molecular basis of strobilation is poorly understood. To assess this issue, an evolutionary comparative study among strobilated and non-strobilated flatworm species was conducted to identify genes and proteins related to the strobilation process. Results: We compared the genomic content of 10 parasitic platyhelminth species; five from cestode species, representing strobilated parasitic platyhelminths, and five from trematode species, representing non-strobilated parasitic platyhelminths. This dataset was used to identify 1813 genes with orthologues that are present in all cestode (strobilated) species, but absent from at least one trematode (non-strobilated) species. Developmentrelated genes, along with genes of unknown function (UF), were then selected based on their transcriptional profiles, resulting in a total of 34 genes that were differentially expressed between the larval (pre-strobilation) and adult (strobilated) stages in at least one cestode species. These 34 genes were then assumed to be strobilation related; they included 12 encoding proteins of known function, with 6 related to the Wnt, TGF-β/BMP, or G-protein coupled receptor signaling pathways; and 22 encoding UF proteins. In order to assign function to at least some of the UF genes/proteins, a global gene co-expression analysis was performed for the cestode species Echinococcus multilocularis. This resulted in eight UF genes/proteins being predicted as related to developmental, reproductive, vesicle transport, or signaling processes. Conclusions: Overall, the described in silico data provided evidence of the involvement of 34 genes/proteins and at least 3 developmental pathways in the cestode strobilation process. These results highlight on the molecular mechanisms and evolution of the cestode strobilation process, and point to several interesting proteins as potential developmental markers and/or targets for the development of novel antihelminthic drugs.

Weighted gene co-expression network analysis reveals immune evasion related genes in Echinococcus granulosus sensu stricto

“…granulosus s.l. inside the group of strobilated platyhelminths [ 28 ], This work is the only one to explore in this way some aspects of the E . granulosus s.s. development, but did not assess differences among parasites collected from different viscera.…”

“…An important limitation of our work that is important to know, is that this approach needs mainly RNA-seq data that considers large number of replicates with low variation among them [ 28 ]. Despite this difficulties, choosing a topology close to a scale free-network seems to be a good model to work on, as despite universality of scale-free networks remains controversial, biological networks appear strongly scale free [ 38 ].…”

Transcriptomic Analysis of the Early Strobilar Development of Echinococcus granulosus

“…Our group has recently compared the genome content of 10 parasitic platyhelminth species with the aim of identify genes and proteins related to the strobilation process [40]. Among the genes that were considered strobilation-related with unknown function, three are differentially expressed in the transcriptome here analyzed.…”

Validation of Reference Genes for RT-qPCR Relative Expression Analysis in Pre-Adult Stages ofTaenia solium

“…With the publication of the T. solium genome 12 and with the first partial cyst transcriptomes obtained by RNA-seq 13,14 ; a valuable amount of data is currently available to study stagespecific events involved in parasite's development 15 . Moreover, whole transcriptome analysis in other tapeworms (including families Taeniidae -genuses Taenia and Echinococcus- [16][17][18][19][20] , Hymenolepididae 21 and Mesocestoididae 22 ) lead to the identification of conserved pathways among cestodes that compliment previous datasets.…”