RESUMO
Studies of the response of p53-lacZ transgenic mice have uncovered an unexpected induction of endogenous acid-beta-galactosidase activity following whole body irradiation. Strong induction of endogenous enzyme activity is seen in a variety of mouse strains commonly used in the production of transgenes. The induction of endogenous enzyme activity therefore complicates the analysis of p53-lacZ transgenes and may also influence the analysis of radiation responses in other lacZ-reporter mice.
Assuntos
Artefatos , Proteínas de Escherichia coli/biossíntese , Genes Reporter , Genes Sintéticos , Genes p53 , Óperon Lac , Lisossomos/enzimologia , Proteínas Recombinantes de Fusão/análise , Proteínas Recombinantes de Fusão/biossíntese , Transgenes , Irradiação Corporal Total , beta-Galactosidase/biossíntese , Animais , Soluções Tampão , Indução Enzimática/efeitos da radiação , Proteínas de Escherichia coli/análise , Proteínas de Escherichia coli/genética , Reações Falso-Positivas , Concentração de Íons de Hidrogênio , Ativação de Macrófagos/efeitos da radiação , Macrófagos/enzimologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Transgênicos , Fagocitose , Glândulas Salivares/enzimologia , Especificidade da Espécie , Baço/enzimologia , Proteína Supressora de Tumor p53/biossíntese , beta-Galactosidase/análise , beta-Galactosidase/genéticaRESUMO
CBA mouse strains have been used for many years as a model of radiation-induced acute myeloid leukaemia and the leukaemias in CBA and their F1 hybrids are characterised by a specific loss of heterozygosity involving one homologue of chromosome 2. Previous cytogenetic studies of transplanted irradiated bone marrow, or of bone marrow obtained from irradiated mice significantly before the appearance of leukaemia, have been interpreted as the chromosome 2 deletion being a high frequency, possibly initiating event. However, these studies had not specifically addressed the question of whether the characteristic deletion was induced at a high frequency in stem cells. Using a PCR-based technique, we have studied the induction of chromosome 2 LOH in the progeny of (CBA/H x C57BL/6)F1 stem cells after a potentially leukaemogenic radiation exposure. Whilst chromosome 2 LOH can be induced directly by irradiation and there is a preferential loss of the CBA allele, the frequency is no greater than LOH induced in other chromosomal regions studied. The data do not support radiation-induced deletion involving one homologue of chromosome 2 in long-term repopulating stem cells (<1 in 200) being as high a frequency event as might be inferred by previous cytogenetic studies of total bone marrow.
