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Master by Research: Gregarine apicomplexan parasites in freshwater invertebrates

School of Applied Sciences

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Dr S Rueckert , Dr J Dodd No more applications being accepted

About the Project

Gregarine apicomplexans are micro-eukaryotic parasites that are found in almost every group of terrestrial, freshwater and marine invertebrates (Leander 2008; Desportes & Schrével 2013). Around 1700 gregarine species have been reported from less than one percent of today’s described invertebrate species, leaving a potential gregarine fauna of 99% of the known invertebrates of the world to be discovered. Gregarines have recently received increased attention due to their recognised importance in the understanding of evolution of parasitism in the Apicomplexa (Janouškovec et al. 2019; Mathur et al. 2019). While they infest invertebrates only, they are closely related to notorious causative agents of e.g. Malaria (Plasmodium), Toxoplasmosis (Toxoplasma) and Cryptosporidiosis (Cryptosporidium), which infect humans and livestock. Given their lifestyle and parasite-host relationship (Rueckert et al. 2019), gregarines represent an intermediate step in the transition from photoautotrophs (as represented e.g. by ’chrompodellids’ in the marine environment) to the most important eukaryotic pathogens of humans and domestic animals.
Gregarine research efforts in the past 15 years have focused on generating phylogentic data beside the morphological description of new species (e.g. Rueckert et al. 2011; Wakeman et al. 2014; Rueckert & Horák 2018), and the first transcriptomic and genomic data have recently been made available (Janouškovec et al. 2019; Mathur et al. 2019) to better understand the evolutionary role of gregarines. One group of gregarines that remains completely underrepresented in any phylogenetic studies is species from freshwater invertebrate hosts. While there are numerous small subunit (SSU) rDNA sequences available for terrestrial and marine gregarines, only a handful of sequences are known from species utilising freshwater hosts.
This project will explore the diversity of gregarine apicomplexans infecting a range of invertebrates (e.g. Gammarus pulex (Amphipoda), Asellus aquaticus (Isopoda), Rhithrogena semicolorata (Ephemeroptera), Isoperla grammatica (Plecoptera), Drusus annulatus (Trichoptera)) in Scottish freshwater habitats around Edinburgh. The research on the systematic and diversity of freshwater gregarine apicomplexans includes six major steps: (1) collection of host organisms, (2) identification and dissection of host organisms, (3) isolation of gregarine parasites, (4) identification, specimen preparation and morphological description of gregarine parasites using light and electron microscopy, (5) molecular characterization of gregarine parasites and (6) digital image processing and molecular phylogenetics.
Outcomes from this research will significantly broaden our knowledge of gregarine apicomplexan parasites from freshwater hosts. The proposed research will focus on the discovery and characterisation of new and poorly known gregarine species from diverse freshwater environments in Scotland. It is anticipated that collected data will lead to new species descriptions, improved resolution of the phylogenetic position of freshwater gregarines and facilitate the identification of environmental sequences that are currently of unknown origin.

Academic qualifications
A first degree (at least a 2.1) ideally in a relevant field such as parasitology, freshwater biology, microbiology, environmental biology or ecology with a good fundamental knowledge of parasitology and laboratory skills including dissections and molecular biology.

English language requirement
IELTS score must be at least 6.5 (with not less than 6.0 in each of the four components). Other, equivalent qualifications will be accepted. Full details of the University’s policy are available online.

Essential attributes:
• Experience of fundamental laboratory skills
• Competent in data analysis and the use of R
• Knowledge of parasitology
• Good written and oral communication skills
• Strong motivation, with evidence of independent research skills relevant to the project
• Good time management

Desirable attributes:
• Good fundamental knowledge and strong interest in aquatic biology, taxonomy, evolution and protistology
• Laboratory skills including dissection, parasite isolation and identification, DNA extraction, PCR, sequencing
• Computational skills for phylogenetic research
• Image processing (e.g. Adobe Photoshop and Illustrator)

This is a self-funded Master by Research project.

Funding Notes

This is an unfunded position


• Desportes, I. & Schrével, J. (2013) Treatise on Zoology – Anatomy, Taxonomy, Biology. The Gregarines. The Early Branching Apicomplexa, BRILL
• Janouškovec, J. et al. (2019) Apicomplexan-like parasites are polyphyletic and widely but selectively dependent on cryptic plastid organelles. eLife 8, e49662
• Leander, B.S. (2008) Marine gregarines: evolutionary prelude to the apicomplexan radiation? Trends Parasitol. 24, 60–67
• Mathur, V. et al. (2019) Multiple independent origins of apicomplexan-like parasites. Curr. Biol. 29, 2936-2941.e5
• Rueckert, S. & Horák, A. (2017) Archigregarines of the English Channel revisited: new molecular data on Selenidium species including early described and new species and the uncertainties of phylogenetic relationships. PLoS One 12, e0187430
• Rueckert S. et al. (2011) Identification of a divergent environmental DNA sequence clade using the phylogeny of gregarine parasites (Apicomplexa) from crustacean hosts. PLoS ONE 6, e18163
• Rueckert, S. et al. (2019) The symbiotic spectrum: Where do the gregarines fit? Trends Parasitol. 35, 687-694
• Wakeman, K.C. et al. (2014) Comparative ultrastructure and molecular phylogeny of Selenidium melongena n. sp. and S. terebellae Ray 1930 demonstrate niche partitioning in marine gregarine parasites (Apicomplexa). Protist 165, 493–511
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