Schistosoma Japonicum Cercariae Escape Rhythms And Tendency Of Adsorption

Part1The impact of photoperiod change on thechronobiology of Schistosoma japonicum cercarialemergenceObjective: To observe the chronobiology of S. japonicum cercarial emergence andthe impact of photoperiod change on this feature.Methods: Infected snails in the hilly region and the marshland were experimentalobjects. The snails were exposed under natural photoperiod, inversion photoperiod,short darkness insert photoperiod for cercarial shedding over24h. Record the number ofcercariae shedding in each2h period. To explore the relationship between photoperiodchanges and cercarial emergence.Results: Snails exposed under natural photoperiod for cercarial shedding. With lateafternoon emergence pattern found in the hilly region, cercariae shedding peak at17pmto21pm. And early emergence pattern within the marshland, cercariae shedding peaksat7am to11am. The photoperiod inversion could reverse the chronobiology of S.japonicum cercarial. Input of a period of2h darkness during7:00～9:00could delay thepeak time of S. japonicum cercarial emergence from the hilly and the marshland snails.Input of a period of2h darkness during17:00～19:00showed no effects on thechronobiology of S. japonicum cercarial emergence from the two regions of snails.Conclusion: S. japonicum cercarial emergence being circadian rhythm, and thechange of photoperiod can affect the chronobiology of S. japonicum cercarialemergence. Part2The tendency attachment of Schistosoma japonicumcercariae and the effect of temperature and cercarial age on thefeatureObjective：To observe the tendency attachment of S. japonicum cercariae, and theinfluence of cercarial age and water temperature on this behavior.Methods: Beeswax and nail varnish (media) were used for their ability to solidify,with the addition of different concentration (0.15g/ml、0.3g/ml、0.6g/ml) of oleic acid,prepared of glass slides to replace the skin for cercarial attached. Blank slides, slideswith nail varnish only, slides with beeswax only as control groups. By inoculation loopto pick50±5cercariae and placed on the previously prepared well slides, after a periodof time cercariae were stained with Lugol’s iodine solution and record the percentage ofthe cercariae which tail lose under microscope, or the slides were washed with waterthree times and then record the number of cercarial head attached on the slides.Results：The percentage of the cercariae tail lose on media containing oleic acidwere statistically significant differences with control media (without oleic acid)(P＜0.01). On media containing the same concentration of oleic acid, the number of cercarialhead attached on slides no obvious difference between freshly emerged cercariae and5hpost-emergence cercariae, with a significant decrease between freshly emergencecercariae and10h post-emergence cercariae (P <0.01). The change of water temperature（25～35℃）did not yield significant results (P>0.05).Conclusions: S. japonicum cercariae have tendency attachment of oleic acid,cercarial age could influence cercarial attachment behavior, water temperature has noobvious influence on them.