British Society of Parasitology, 11-13 April 2016
31/03/16 17:34
Join us at Imperial College, London, for the British Society of Parasitology where Pete and Francesca will make the following presentations:Thursday, April 13 - 2:45-3:00
LT 340 - Huxley Building
Session: Helminth Signalling and Developmental Parasitology I
From planarians to parasitism: Wnt/Hedgehog signalling controls AP patterning during larval and strobilar development in tapeworms
Francesca Jarero*, Uriel Koziol & Peter D. Olson
Wnt/Hedgehog signalling in free-living planarians is responsible for mediating head/tail decision making during early development and in regeneration. More broadly, canonical Wnt signalling has been found to underlie AP axis formation in animals generally. We show that AP specification during larval metamorphosis in tapeworms also involves canonical Wnt signalling, with scolex formation taking place at the site(s) of Wnt repression. Moreover, we show that the same system has been co-opted during strobilar development, with segmental boundaries expressing opposing ‘stripes’ of anteriorizing (SFRP) and posteriorizing (Wnt1) signals—tapeworm strobilation therefore being a form of paratomy. Expression of Hedgehog and Hox also appear linked to the system, upstream and downstream of Wnt signaling, mirroring the model of AP signalling in planarians as presently understood. Taken together, we show that parasitic and free-living flatworms share the same underlying AP patterning system despite their highly disparate body plans.
Thursday, April 13 - 3:45-4:15
LT 340 - Huxley Building
Session: Helminth Signalling and Developmental Parasitology II
Tapeworm tumours: how not to make a tapeworm
Peter D. Olson* & Atis Muehlenbachs
In a recently reported case of dwarf tapeworm (Hymenolepis nana) infection in an HIV-positive Columbian man (NEJM 373:1845-52), tumours were found in the lymph nodes, lungs and elsewhere that appeared to comprise non-human cells. Genetic analyses confirmed these to be H. nana cells, and their small size (< 10 um), spherical shape and low cytoplasm/nuclear ratio were all consistent with tapeworm germinative cells or ‘neoblasts' (i.e. flatworm stem cells). With the exception of a degree of syncitia formation (characteristic of tapeworm tissue architecture generally) no cell differentiation was seen. However clonal proliferation and evasive dissemination was evidenced by genetic analysis and the tumours proved fatal. Preliminary genomic analysis comparing the case study with a reference laboratory isolate revealed breaks in genes previously implicated in human cancers (e.g. LAMP2). I describe this case together with previous cases of tapeworm infection in immunocompromised patients in order to illustrate the most likely route of infection and demonstrate the necessity for cross-talk with the host’s immune system for normal development of the parasite. Lastly, I will briefly outline why studying parasites as animals rather than as some unique category of being is essential for understanding their biology and informs applied areas of NTD research.