Budding of Taenia crassiceps Cysticerci In Vitro Is Promoted by Crowding in Addition to Hormonal, Stress, and Energy-Related Signals

Taenia crassiceps cysticerci (cysts) reproduce by budding. The cysts' production of buds was measured in vitro to explore parasite and environmental-related factors involved in the extreme individual variation in parasite loads of inbred mice. Cysts were placed in in vitro culture for 10 days at initial parasite densities of 1, 5, 10 cysts/well in 1 ml of RPMI Medium 1640 without serum. Results showed that there is considerable intrinsic initial variation among inoculated cysts in their production of buds and that increasing parasite density (crowding) stimulates the overall production of buds and recruit into budding most of the cysts. Identical cultures were then subjected to various treatments such as heating and exposure to peroxide to induce stress, or to 17beta-estradiol, insulin, glucose, or insulin+glucose to supplement putatively limiting hormonal and energy resources. All treatments increased budding but the parasites' strong budding response to crowding alone overshadows the other treatments.