title: Toxicity of two type II ribosome-inactivating proteins (cinnamomin and ricin) to domestic silkworm larvae.
abstract: Cinnamomin and ricin are two type II ribosome-inactivating proteins. They exhibited a different toxicity to domestic silkworm (Bombyx mori) larvae by oral feeding bioassay. The LC50 of ricin to the silkworm larvae at third instar was much lower than that of cinnamomin. When the isolated 80S ribosome from domestic silkworm pupae was treated separately with the reduced cinnamomin or the reduced ricin, a specific RNA fragment (R-fragment) was produced as characterized by 8 M urea-denatured polyacrylamide gel (3.5%) electrophoresis. The purified A-chains of both cinnamomin and ricin showed a slightly different RNA N-glycosidase activity to the domestic silkworm pupal ribosome. It was proposed that the difference of their toxicity to domestic silkworm larvae was not related to their A-chains but to the properties of their B-chains. It was also found that the vomit obtained from the midgut of domestic silkworm larvae could hydrolyze these two proteins apparently to a similar extent.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Wei
authors.forename: Ren-Shui
authors.initials: RS
authors.lastname: Liu
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.forename: Wang-Yi
authors.initials: WY
authors.lastname: Liu
mesh_terms: D020418:Algal Proteins; D000818:Animals; D012831:Bombyx / Q000187:drug effects*; D004591:Electrophoresis, Polyacrylamide Gel; D005766:Gastrointestinal Contents / Q000737:chemistry; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D011506:Proteins / Q000633:toxicity*; D054790:Ribosome Inactivating Proteins, Type 2; D012270:Ribosomes / Q000187:drug effects*; D012276:Ricin / Q000633:toxicity*
chemical_list: D020418:Algal Proteins; D011506:Proteins; D054790:Ribosome Inactivating Proteins, Type 2; C061930:cinnamomin, Phytophthora cinnamomi; D012276:Ricin