Schistosoma mansoni cercariae shedding
Sarah K Buddenborg, Matt Berriman, Geetha Sankaranarayanan, Magda E Lotkowska, Catherine McCarthy, Arporn Wangwiwatsin, Carmen L Dias Soria, Lisa Seymour, Gabriel Rinaldi
Abstract
Schistosoma mansoni cercariae can be obtained from infected Biomphalaria glabrata snails. Although infected snails will release (shed) cercariae constantly at low numbers, it is possible to trigger the release of larger quantities by keeping the snails in the dark for a few days before shedding.
Material obtained from these procedures can be mechanically transformed into schistosomula for further experimentation.
Before start
Steps
Preparing snails for shedding
Place aquarium tank containing snails >=4 weeks post-exposure to S. mansoni on a stable bench top
Using featherweight forceps, remove snails from the tank and rinse gently with 1x aquarium water in a wash bottle
- This is critical in order eliminate false positives (snails with cercariae on them from a different shedding snail)
Place snails into labelled 12- or 24-well plates with one snail per well
Shedding snails
Place cover on plate and place snails under LED or fluorescent lighting for up to 2 hours to trigger release of cercariae from the infected snails.
Add enough 1x aquarium water to each well so that they are covered
Check snails for shedding by viewing each well under a zoom stereomicroscope with diascopic illumination stand
Collecting cercariae
Collect water containing cercariae every 30 minutes (alternatively, you can just collect cercariae at the end of 2 hrs shedding; this will give you the most concentrated cercariae suspension) using a transfer pipet and top up wells with new 1x aquarium water
- If needed (i.e. for monomiracidium-infected snails where separate sexes are needed), keep cercariae from each snail separate and use new transfer pipet for each snail
Dispose of snails that did not shed by putting them in a container klorsept (See "Guidelines and Warnings") or place in new tank if you'd like to re-shed after an additional week.
Return shedding snails to a new tank with food and appropriate labels – make sure their air stones are under the water level and bubbling properly (See protocol "Snail husbandry for maintaining the Schistosoma mansoni life cycle")
