Objective To discriminate whether chemical compounds are micronuclei-inducing by counting the ratio of bone marrow micronucleus polychromatic erythrocytes ( MNPCE) dyed with a single fluorescence reagent ( acriding organe, AO) by single-laser flow cytometry.Methods Treating male KM mice and SD rat with cyclophosphamide ( CP) respectively, and counting their frequencies of micronucleated polychromatic erythrocytes ( MNPCE) as well as frequencies of micronucleated normochromatic erythrocytes ( MNNCE ) in bone marrow by AO and a single_laser flow cytometer (FCM), comparing and analyzing the results from different methods.Results The results showed that, along with increasing dose of CP, the ratio of MNPCE also corresponding increase, suggesting significant quantative-efficiency correlation.MNPCE were also counted manually by fluorescence microscopy, and the results showed no significant difference with that by flow cytometry.Conclusions AO_FCM fully automated detection method for the detection of MNPCE and MNNCE in mice and rat bone marrow micronucleus rate is reliable.

Objective The aim of this study was to investigate the masculinizing effects of progesterone ( PRO) exposure at different concentrations on the morphology of female mosquitofish (Gambusia affinis).Methods Immature female G.affinis individuals were put into static water with 0.5, 5, 50 and 500 nmol/L progesterone (n=56), respective-ly.In addition, control group and parallel groups were set up .After 42-day-long exposure, we measured four main indexes of the G.affinis:the body length, body weight, morphological changes in the anal fin 3rd fin and the 14, 15 and 16 verte-bral ribs.We also observed the state of ovarian development .Results The body lengths (BL) of experimental groups ex-posed at concentration of 50 and 500 nmol/L progesterone for 42 d showed significant differences , respectively ( P<0.01 for both), when compared with those of the control group .The body weights (BW) of experimental groups exposed to pro-gesterone at all concentrations were significantly or very significantly decreased (P<0.05 or P<0.01).Only the proges-terone at 5 nmol/L concentration showed significant effect on the body health index (CF) (P<0.05).The section number (FJ) of the anal fin 3rd fin, the section length (FL)and the widest portion width (FW)in the experimental groups had sig-nificant difference (P<0.05), respectively, showing significant changes in morphology after the exposure to 500 nmol/L progesterone .However , there was no significant difference between the values resulted by progesterone in other concentra -tions (P>0.05).When exposed to 500 nmol/L PRO, the L, D and L:D values of the 14th, 15th and 16th vertebral ribs of the female G.affinis had very significant difference ( P<0.01 for all ) , respectively , indicating significant changes of morphological masculinization .Histological examination revealed that the developmental status of the ovaries of G.affinis in the experimental groups were to different degrees inhibited , and the nuclei appeared swelling in stage II and III oocytes . Conclusions The results of this study indicate apparent masculinizing effects of progesterone on immature female mosquit -ofish.