title: Intracytoplasmic type A particles from mammary tumours and leukaemias of strain ICRC mice.
abstract: The ovarian-hormone-induced leukaemias of strain ICRC mice, with an abundance of intracytoplasmic type A particles in primary as well as transplanted lesions, were used to study morphological, biophysical, immunological and structural characteristics of type A particles. Mammary tumours of strains ICRC and C3H(Jax) were also used as sources for type A particles. The purified virions banded at the density of 1.20 g/ml in 12--60% linear sucrose-density gradient when subjected to spinning at 113,000 g for 4 h. The SDS-polyacrylamide-gel electrophoresis of type A particles from mammary tumours and leukaemias reproducibly resolved at least 8 polypeptides, 2 of these 54,000 and 24,000 dalton proteins, showing variable expression. Type A particles and B particles, despite the fact that each had a distinct polypeptide pattern, showed common antigens with different electrophoretic mobilities. Proteins of 24,000, 18,000 and 12,000 daltons from B particles were found to be antigenically related to those from type A particles. The bioassay studies carried out with purified A particles showed that 2/7 males of strain ICRC and 1/6 females of strain DBA-MTI developed leukaemias, as against none in the controls, when inoculated between the ages of 1-7 days. Spleen tumour and cervical tumour were seen in one female each of strain DBA-MTI.
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient; D003593:Cytoplasm / Q000648:ultrastructure; D005260:Female; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007181:Inclusion Bodies, Viral / Q000032:analysis / Q000648:ultrastructure*; D007942:Leukemia, Experimental / Q000032:analysis / Q000648:ultrastructure*; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000032:analysis / Q000648:ultrastructure*; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D009368:Neoplasm Transplantation; D010455:Peptides / Q000032:analysis; D014184:Transplantation, Homologous; D014771:Virion / Q000032:analysis / Q000648:ultrastructure
chemical_list: D010455:Peptides