The aim of this study was to determine the differences in phototaxis between Oncomelania hupensis (O .h .) hupensis and O .h .robertsoni as well as four related geographic strains of male and female snails and Schistosoma japonicum-infected and-uninfected snails .Field collection of O . hupensis was performed in S . j aponicum-endemic areas of Xingzi and Yushan counties in Jiangxi Province ,China ,as well as Tianquan and Pengshan counties in Sichuan Province ,China .Infected and uninfected snails were screened using the cercariae escaping method ,with artificial separation of male and female snails . The experiment was carried out in an in-house constructed dark phototaxis experiment box using white light as the main source of light at the most suitable light intensity .Under a light intensity of 1 500 Lux for 30 minutes ,all of the snails from the experimental group showed obvious phototaxis .The statistical analysis showed no significant difference in the phototaxis index between male and female snails ,and there was also no significant difference in the phototaxis index between different geograph-ical strains of the same subspecies of snails .A significant difference in phototaxis was observed between the two subspecies during the 30-minute experimental period :O .h .hupensis displayed a higher phototaxis index than that of O .h .robertsoni , whereas S .japonicum-infected snails showed a lower phototaxis index than that of uninfected snails .A difference in phototaxis was found between different subspecies of O .hupensis and within the same subspecies .All uninfected snails displayed the same phototaxis index .When snails were infected with S .japonicum ,phototaxis reduced .

Objective:To explore the potent effects of denatonium benzoate(DB)on Mas-related G protein-coupled receptor-B2(MrgprB2)-mediated rat mast cell degranulation.Methods:RBL-2H3 cells were treated with DB overnight,before challenged with MrgprB2 ligands substance P(SP).The release of β-hex from MrgprB2-activated RBL-2H3 was detected by substrate method.Detec-tion of LTC4,IL-6,TNF-α and cPLA2 activity were performed by ELISA.The Ca2+influx and the expression of RBL-2H3 MrgprB2 re-ceptors were measured by fluorescence assay.Results:The results showed 10 μmol/L,50 μmol/L,80 μmol/L,100 μmol/L DB treat-ments promoted β-hex and LTC4 releases from activated RBL-2H3,accompanied by increased Ca2+mobilization and cPLA2 activa-tion.DB treatments did not affect IL-6 and TNF-α LTC4 releases in MrgprB2-activated RBL-2H3,as well as the levels of MrgprB2 ex-pression in mast cells.Conclusion:Taken together,DB enhanced the MrgprB2-mediated RBL-2H3 degranulation in vitro,probably by up-regulating Ca2+mobilization in activated cells.