Molecular signatures of the rediae, cercariae and adult worm stages in the complex life cycles of parasitic flatworms (Psilostomatidae, Trematoda)

Abstract

Trematodes are one of the most remarkable animals with complex life cycles with several generations. Life histories of a parasitic flatworms include several stages with disparate morphological and physiological characteristics follow each other and infect hosts ranging from mollusks to higher vertebrates. How does one genome regulate the development of various life forms and how many genes are needed to the functioning of each stages? How similar are molecular signatures of life stages in closely related species of parasitic flatworms? Here we present the comparative analysis of transcriptomic signatures of the rediae, cercaria and adult worm stages in two representatives of the family Psilostomatidae (Echinostomata, Trematoda) -Psilotrema simillimumandSphaeridiotrema pseudoglobulus. Our results indicate that the transitions between the stages of the complex life cycle are associated with massive changes in gene expression with thousands of genes being stage-specific. In terms of expression dynamics, the adult worm is the most similar stage betweenPsilotremaandSpaeridiotrema, while expression patterns of genes in the rediae and cercariae stages are much more different. This study provides transcriptomic evidences not only for similarities and differences between life stages of two related species, but also for cryptic species inSphaeridiotrema.

The digenean complex life cycle: phylostratigraphy analysis of the molecular signatures

“…In the current research, we used publicly available data for flatworms both free-living - (Howe et al, 2017) database were analyzed. The reference transcriptomes of P. simillimum (Nesterenko et al, 2020), P. vittatus (Brandl et al, 2016;Martín-Durán et al, 2017) (PlanMine: bg_Pvit_v1), T. regenti (Leontovyč et al, 2016) (after direct request), and T. szidati (Leontovyč et al, 2019) (after direct request) were used. To reduce the redundancy of transcriptome data, the MMseqs2 (Mirdita, Steinegger and Söding, 2019) clustering algorithm was applied on sets of predicted amino acid sequences with the following parameters: mmseqs easy-cluster -cov-mode 0 -min-seq-id 0.9.…”

“…We used the paired-end libraries of raw reads for F. gigantica (eggs, miracidia, rediae, cercariae, metacercariae, 42-days-old and 70-days-old juveniles, adults) (Zhang et al, 2019), F. hepatica (eggs, metacercariae, NEJ at 1, 3 and 24 hours post excystment, 21-day-old juveniles, and adult) (Cwiklinski et al, 2015;McNulty et al, 2017), P. simillimum (rediae, cercariae, adults) (Nesterenko et al, 2020), S. mansoni (cercariae, 3 hours and 24 hours post-infection schistosomula, and 7-weekold mixed sex adults) (Protasio et al, 2012), T. regenti (cercariae, schistosomula) (Leontovyč et al, 2016), and T. szidati (cercariae, schistosomula) (Leontovyč et al, 2019). A complete list of library identifiers is provided in the Supplementary Table S1.…”

“…The living abilities of LCS require complex regulation of genome activity. Previously, we analyzed gene expression in two Psilostomatidae species during their complex life cycles (Nesterenko et al, 2020). In this study, we updated the set of analyzed data to clarify and expand our notions of the genome activity: 1) what is the molecular signature of different LCS, 2) how many genes have a noticeable expression throughout the life cycle, 3) how many genes are differentially expressed between the LCS, and 4) how many clusters of co-expressed genes can be found in different species.…”

From head to rootlet: comparative transcriptomic analysis of a rhizocephalan barnacle Peltogaster reticulata (Crustacea: Rhizocephala)

“…A rapid development of high-throughput sequencing technologies has enabled detailed molecularbiological studies of many living organisms (for example, [21][22][23][24][25]) but until recently molecular studies on Rhizocephala have been lacking. The research on body heterogony, host-parasite interactions and functional physiology was based only on the morphological and other classical methods.…”