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Table 1 Conversion rates for newly transformed schistosomula (NTS) of Schistosoma mansoni obtained using a modified vortex transformation procedure

From: The antioxidants resveratrol and N-acetylcysteine enhance anthelmintic activity of praziquantel and artesunate against Schistosoma mansoni

Experiment Description Cercarial suspension (ml) No. of cercariae No. of schistosomula Conversion rate (%) Mean ± SD Observations
1 Reduced motility: 30 min on ice; centrifugation: 800× rpm, 5 min, 4 °C; purification: 3 steps (15 min on ice) 35 3500 1750 50.0 a Experiment 1 and 2: lower conversion rate; considerable number of tails and cercariae detected
2 Reduced motility: 30 min on ice; centrifugation: 800× rpm, 5 min, 4 °C; purification: 5 steps (15 min on ice) 38 6080 2800 47.0 61.4 ± 10.2
3 22.5 3825 2900 75.8 Despite an increase in the schistosomula conversion rate, several tails were observed in wells
4 Reduced time between purification steps (15–10 min) (centrifuged 2× in order to obtain a solid pellet); slight increase of vortexing time 45 5850 3240 55.0 a Alteration of culture supplemented media M199, 20 mM HEPES, 10% iFBS. It is probable that the time of initial suspension on ice was insufficient to decrease parasite motility, which led to a loss of cercariae after supernatant removal
5 25 10,000 Due to higher number of cercariae in initial suspension, it is probable that the time on ice was not enough to reduce motility. Consequently, it did not form a solid pellet after centrifugation leading to release of cercariae after removal of supernatant
6 Experiments 6–12: reduced motility: 60 min on ice; centrifugation: 1000× rpm, 10 min, 4 °C; purification similar to experiments 4 and 5; introducing checkpoints during the transformation method 50 5250 3720 70.9 68.6 ± 4.8 Fewer cercariae and tails detected. Good parasite fitness. Increased of concentration of iFBS to 15%. Final culture media established as supplemented M199 with HEPES and 10% FBS
7 100 11,750 7380 62.8 Due to a great number of cercariae, mechanical transformation was performed on separated tubes
8 40 12,000 8640 72.0 Experiment 8 and 9: lower number of tails and cercariae. Good parasite fitness
9 50 3000 2250 75.0
10 27.5 1640 1040 63.4 Lower number of cercariae because several infected snails had died, thus only a few snails were infecting and shedding cercariae. In this case, we only performed 4 steps for purification in order to reduce loss of schistosomula during the process
11 50 4625 3000 64.8 Lower number of tails and cercariae, as well good parasite fitness
12 50 7375 5265 71.4
  1. aUnable to calculate mean and standard deviation (SD)