A Genome Wide Comparison to Identify Markers to Differentiate the Sex of Larval Stages of Schistosoma haematobium, Schistosoma bovis and their Respective Hybrids

Abstract

For scientists working on gonochoric organisms, determining sex can be crucial for many biological questions and experimental studies, such as crossbreeding, but it can also be a challenging task, particularly when no sexual dimorphism is visible or cannot be directly observed. In metazoan parasites of the genus Schistosoma responsible for schistosomiasis, sex is genetically determined in the zygote with a female heterogametic ZW/ZZ system. Adult flukes have a pronounced sexual dimorphism, whereas the sexes of the larval stages are morphologically indistinguishable but can be distinguished uniquely by using molecular methods. Therefore, reliable methods are needed to identify the sex of larvae individuals. Here, we present an endpoint PCR-based assay using female-specific sequences identified using a genome-wide comparative analysis between males and females. This work allowed us to identify sex-markers for Schistosoma haematobium and Schistosoma bovis but also the hybrid between both species that has recently emerged in Corsica (France). Five molecular sex-markers were identified and are female-specific in S. haematobium and the hybrid parasite, whereas three of them are also female-specific in S. bovis. These molecular markers will be useful to conduct studies, such as experimental crosses on these disease-causing blood flukes, which are still largely neglected but no longer restricted to tropical areas.

Sex chromosome and sex locus characterization in goldfish, Carassius auratus (Linnaeus, 1758)

“…Because RAD-sequencing keeps track of each individual, we were able to identify sexreversed individuals in goldfish that might have masked sex-linked markers in Pool-seq. Sex markers identification is an important step to characterize SD systems [32][33][34][35][36][37][38]. Using two complementary whole-genome approaches, we characterized genomic regions containing sex-linked markers.…”

Morphological and genomic characterisation of the hybrid schistosome infecting humans in Europe reveals a complex admixture between Schistosoma haematobium and Schistosoma bovis parasites

“…Adult worms produced in hamsters were recovered after portal perfusion and male/female couples were manually separated. Detailed methods were described previously [32], Schistosoma bovis (Spain) and Schistosoma haematobium (Cameroon) were also maintained in the lab using Planorbarius metidjensis and Bulinus truncatus as intermediate hosts, respectively, and Mesocricetus auratus hamsters as definitive hosts [33]. F1 hybrids were produced after experimental cross between male S. haematobium and female S. bovis.…”

“…For that, we infected molluscs with a single miracidium of the parental species to obtain male or female clonal cercariae. The latter were sexed using molecular markers efficient on both species that we developed previously [33]. We simultaneously exposed hamsters to 300 cercariae of male S. haematobium and 300 cercariae of female S. bovis.…”

Sex chromosome and sex locus characterization in the goldfish, Carassius auratus

“…Because sequencing keeps track of each individual, we were able to identify sex-reversed individuals in 200 goldfish that might have masked sex-linked markers in Pool-seq. 201 202 Sex markers identification is an important step to characterize SD systems [32][33][34][35][36][37][38]. Using two 203 complementary whole-genome approaches, we characterized genomic regions containing sex-204 linked markers.…”