title: Developmental physiology of cestodes. XVII. Some biological properties of putative "crowding factors" in Hymenolepis diminuta.
abstract: A "worm conditioned saline" (WCS) was prepared by incubation of 10-day-old Hymenolepis diminuta (Cestoda: Cyclophyllidea) from infections varying in population density (10, 50, 100 worms per host). Upon subsequent testing on 10-day-old worms from uncrowded (10 worms) infections, WCS prepared with worms from more crowded populations inhibited 3H-thymidine incorporation into DNA to a greater degree than did WCS prepared with worms from less crowded populations. WCS prepared with adult worms (20-30 days old) from crowded (50-worm) infections also inhibited DNA synthesis in 10-day-old cestodes from 10-worm infections. WCS from the anterior ends of adult worms was more inhibitory than WCS prepared with gravid proglottids. The time course of the inhibition was consistent with a G1 block in the cell cycle of the stem cells of the germinative area. The experiments lend support to the hypothesis that these cestodes secrete "crowding factors" that inhibit the growth of other H. diminuta in the same rat.
mesh_terms: D000085:Acetates / Q000032:analysis; D000818:Animals; D004247:DNA / Q000096:biosynthesis; D006131:Growth Inhibitors / Q000032:analysis / Q000502:physiology*; D006926:Hymenolepis / Q000254:growth & development / Q000502:physiology*; D007399:Interphase; D012965:Sodium Chloride; D013386:Succinates / Q000032:analysis; D019802:Succinic Acid
chemical_list: D000085:Acetates; D006131:Growth Inhibitors; D013386:Succinates; D012965:Sodium Chloride; D004247:DNA; D019802:Succinic Acid