The neuromuscular system of the sheep tapeworm Moniezia expansa
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ORIGINAL ARTICLE
The neuromuscular system of the sheep tapeworm Moniezia expansa Gunnar R. Mair1 · David W. Halton2 · Aaron G. Maule2 Received: 21 May 2020 / Accepted: 5 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Cestodes are common gastrointestinal parasites of humans and livestock. They attach to the host gut and, without a mouth or intestinal system, absorb nutrients through their epidermis. Here we show that despite this simplified anatomy and sessile lifestyle, they maintain a complex neuromuscular system. We used fluorescently labelled phalloidin as a specific probe for filamentous actin to define the overall organisation of several distinct muscle systems in the cyclophyllidean Moniezia expansa. Like all flatworms, the body wall musculature below the neodermis of this intestinal parasite of sheep is characterised by outer circular and inner longitudinal muscle fibres. Diagonal fibres, typically found in free-living and trematode platyhelminths, on the other hand, are notably absent. Prominent longitudinal sheaths dominate the parenchyma and provide retractor muscles to the four acetabula in the scolex; they attach at the bottom of each cup-shaped holdfast. Within sexually mature proglottids, circular fibres dominate the duct walls of the male and female reproductive systems. Nerve cells and fibres that express serotonin or neuropeptide F supply well-developed innervation to several of the described muscle systems: emanating from the central nervous system, fibres in the periphery develop pervasive nerve nets that anastomose within body wall musculature as well as the parenchymal longitudinal and oblique muscle fibres, and innervate the sexual organs and gonopore in mature proglottids. Using homology searches, we provide evidence for 20 neuropeptide precursors together with four prepropeptide processing enzymes as well as several 5-HT signalling components to be represented in the Moniezia transcriptome. Keywords Moniezia · Cestode · NPF · FMRFamide · Serotonin neuromuscular · Phalloidin
Introduction Cestodes are global parasites of humans and livestock (Budke et al. 2009). The cyclophyllidean (Anoplocephalidae) tapeworm Moniezia expansa inhabits the small intestine of sheep and other ruminants and can grow up to several meters in length (McKay and Webb 2006; Ndom et al. 2016). Moniezia has been key to the ground-breaking, biochemical-based discovery of the first flatworm neuropeptides: a Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10158-020-00246-2) contains supplementary material, which is available to authorised users. * Gunnar R. Mair [email protected] 1
Biomedical Sciences, Iowa State University, 1800 Christensen Drive, 2008 Vet Med, Ames, IA 50011‑1134, USA
School of Biological Sciences, Queen’s University of Belfast, Belfast BT9 5DL, UK
2
homologue of the neuropeptide F/Y family and the short FMRFamide-related peptide GNFFRFamide (Maule et al. 1991, 1993). Together with serotonin, these and rela
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