RESUMO
Objective To evaluate the molluscicidal activity of surfactin against Oncomelania hupensis, so as to provide the experimental basis for use of Bacillus for killing O. hupensis. Methods O. hupensis snails were collected from schistosomiasisendemic foci of Wuhu City on September 2022, and Schistosoma japonicum-infected snails were removed. Then, 60 snails were immersed in surfactin at concentrations of 2, 1, 0.5, 0.25, 0.125 mg/mL and 0.062 5 mg/mL for 24, 48, 72 hours at 26 °C, while ultrapure water-treated snails served as controls. The median lethal concentration (LC50) of surfactin against O. hupensis snails was estimated. O. hupensis snails were immersed in surfactin at a concentration of 24 h LC50 and ultrapure water, and then stained with propidium iodide (PI). The PI uptake in haemocyte was observed in O. hupensis snails using fluorescence microscopy. Results The mortality of O. hupensis was 5.0% following immersion in surfactin at a concentration of 0.062 5 mg/mL for 24 h, and the mortality was 100.0% following immersion in surfactin at a concentration of 2 mg/mL for 72 h, while no snail mortality was observed in the control group. There were significant differences in the mortality of O. hupensis in each surfactin treatment groups at 24 (χ2 = 180.150, P < 0.05), 48 h (χ2 = 176.786, P < 0.05) and 72 h (χ2 = 216.487, P < 0.05), respectively. The average mortality rates of O. hupensis were 38.9% (140/360), 62.2% (224/360) and 83.3% (300/360) 24, 48 h and 72 h post-immersion in surfactin, respectively (χ2 = 150.264, P < 0.05), and the 24, 48 h and 72 h LC50 values of surfactin were 0.591, 0.191 mg/mL and 0.054 mg/mL against O. hupensis snails. Fluorescence microscopy showed more numbers of haemocytes with PI uptake in 0.5 mg/mL surfactintreated O. hupensis snails than in ultrapure water-treated snails for 24 h, and there was a significant difference in the proportion of PI uptake in haemocytes between surfactin-and ultrapure water-treated snails (χ2 = 6.690, P < 0.05). Conclusion Surfactin is active against O. hupensis snails, which may be associated with the alteration in the integrity of haemocyte membrane.
RESUMO
Five types of haemocytes have been identified in the haemolymph of Spilostethus hospes. Their morphology and micrometric measurements have been provided. Changes in the total and differential haemocyte population [total haemocyte count (THC) and differtial haemocyte count (DHC)] as well as in the absolute number of haemocytes in circulation have been assessed in relation to eclosion, sex and mating. The haemogram profile was studied prior to and immediately after eclosion and also prior to and after copulation. Though the THC was not significantly different immediately before and after eclosion, there was a significant increase in total count prior to copulation. Mated females registered an increase in total count but there was no appreciable change in the mated males. Granulocytes were the most abundant of the haemocyte types in both the sexes and mating caused a significant increase in the plasmatocyte count in females. Changes in the blood volume as well as the mitotic activity of the haemocytes is also discussed.
RESUMO
Objectives To establish method for collecting haemocytes of Oncomelania hupensis and study its morphology and immunological importance. Methods Referring to the method of haemocytes collection from peripheral lymphoid organ, suspension technique was used for collection of haemocytes from snails, which were then Giemsa-stained and observed under microscope. Stained by gentian violet, number of haemocytes was counted and compared with that of conventional squashing method and needling method by ANOVA and Dunnett-t test. Supernatant from freeze thawing haemocytes was applied for the tests of immuno-precipitation, bacteriostasis, and phagocytosis. SDS-PAGE was used to analyze relative molecular mass of protein ingredients. Results Four kinds of haemocytes were found: round cells with filiform filopodia, acidophilic and basophilic round cells both without filiform filopodia, and spindle cells. The average diameter of the 4 type cells was 10.93, 6.13, 6.08, and 11:06?m, and occupied 50%, 30%, 5%, and 15% respectively. The mean of haemocytes received from suspension, squashing and needling methods was 15 000, 6 600 and 300/ml respectively. ANOVA analysis showed F=281.47, P