@article{wilson_mclachlan_falls_leblanc_1999, title={Alteration in sexually dimorphic testosterone biotransformation profiles as a biomarker of chemically induced androgen disruption in mice}, volume={107}, ISSN={["1552-9924"]}, DOI={10.2307/3434541}, abstractNote={Assessment of the impact of environmental chemicals on androgen homeostasis in rodent models is confounded by high intraindividual and interindividual variability in circulating testosterone levels. Our goal was to evaluate changes in testosterone biotransformation processes as a measure of androgen homeostasis and as a biomarker of exposure to androgen-disrupting chemicals. Sex-specific differences in hepatic testosterone biotransformation enzyme activities were identified in CD-1 mice. Gonadectomy followed by replacement of individual steroid hormones identified specific sex differences in biotransformation profiles that were due to the inductive or suppressive effects of testosterone. Notably, significant androgen-dependent differences in testosterone 6[alpha]- and 15[alpha]-hydroxylase activities were demonstrated, and the ratio of 6[alpha]- and 15[alpha]-hydroxylase activities proved to be an excellent indicator of the androgen status within the animal. The male or "masculinized" testosterone 6[alpha]/15[alpha]-hydroxylase ratio was significantly less than the female or "feminized" ratio. Male mice were exposed to both an antiandrogen, vinclozolin, and to a compound that modulates serum androgen levels, indole-3-carbinol, to test the utility of this ratio as a biomarker of androgen disruption. Treatment with the antiandrogen vinclozolin significantly increased the 6[alpha]/15[alpha]-hydroxylase ratio. Indole-3-carbinol treatment resulted in a dose-dependent, but highly variable, decrease in serum testosterone levels. The 6[alpha]/15[alpha]-hydroxylase ratio increased as serum testosterone levels decreased in these animals. However, the increase in the ratio was much less variable and more sensitive than serum testosterone levels. These investigations demonstrate that the 6[alpha]/15[alpha]-hydroxylase ratio is a powerful measure of androgen modulation and a sensitive indicator of exposure to androgen-disrupting chemicals in CD-1 mice.}, number={5}, journal={ENVIRONMENTAL HEALTH PERSPECTIVES}, author={Wilson, VS and McLachlan, JB and Falls, JG and LeBlanc, GA}, year={1999}, month={May}, pages={377–384} }
 @article{hodgson_cherrington_coleman_liu_falls_cao_goldstein_rose_1998, title={Flavin-containing monooxygenase and cytochrome P450 mediated metabolism of pesticides: from mouse to human}, volume={2}, number={1998}, journal={Reviews in Toxicology}, author={Hodgson, E. and Cherrington, N. and Coleman, S. C. and Liu, S. and Falls, J. G. and Cao, Y. and Goldstein, J. E. and Rose, R. L.}, year={1998}, pages={231–243} }
 @article{cherrington_falls_rose_clements_philpot_levi_hodgson_1998, title={Molecular cloning, sequence, and expression of mouse flavin-containing monooxygenases 1 and 5 (FMO1 and FMO5)}, volume={12}, DOI={10.1002/(sici)1099-0461(1998)12:4<205::aid-jbt2>3.3.co;2-4}, abstractNote={Full-length cDNA clones encoding FMO1 and FMO5 have been isolated from a library constructed with mRNA from the liver of a female CD-1 mouse. The derived sequence of FMO1 contains 2310 bases: 1596 in the coding region, 301 in the 5′-flanking region, and 413 in the 3′-flanking region. The sequence for FMO5 consists of 3168 bases; 1599 in the coding region, 812 in the 5′-flanking region, and 757 in the 3′-flanking region. The sequence of FMO1 encodes a protein of 532 amino acids with a predicted molecular weight of 59.9 kDa and shows 83.3% identity to human FMO1 and 83–94% identity to other FMO1 homologs. FMO5 encodes a protein of 533 amino acids with a predicted molecular weight of 60.0 kDa and 84.1% identity to human FMO5 and 83–84% identity to other FMO5 orthologs. Two GxGxxG putative pyrophosphate binding domains exist beginning at positions 9 and 191 for FMO1, and 10 and 192 for FMO5. Mouse FMO1 and FMO5 were expressed in E. coli and show similar mobility to the native proteins as determined by SDS-PAGE. The expressed FMO1 protein showed activity toward methimazole, and FMO5 was active toward n -octylamine. In addition, FMO1 was shown to metabolize radiolabeled phorate, whereas FMO5 showed no activity toward phorate. © 1998 John Wiley & Sons, Inc. J Biochem Toxicol 12: 205–212, 1998}, number={1998}, journal={Journal of Biochemical and Molecular Toxicology}, author={Cherrington, N. J. and Falls, J. G. and Rose, R. L. and Clements, K. M. and Philpot, R. M. and Levi, P. E. and Hodgson, E.}, year={1998}, pages={205–212} }
 @article{falls_cherrington_clements_philpot_levi_rose_hodgson_1997, title={Molecular cloning, sequencing, and expression in Escherichia coli of mouse flavin-containing monooxygenase 3 (FMO3): Comparison with the human isoform}, volume={347}, ISSN={["0003-9861"]}, DOI={10.1006/abbi.1997.0322}, abstractNote={The sequence of mouse flavin-containing monooxygenase 3 (FMO3) was obtained from several clones isolated from a mouse liver cDNA library. The nucleotide sequence of mouse FMO3 was 2020 bases in length containing 37 bases in the 5' flanking region, 1602 in the coding region, and 381 in the 3' flanking region. The derived protein sequence consisted of 534 amino acids including the putative flavin adenine dinucleotide and NADP+ pyrophosphate binding sites (characteristic of mammalian FMOs) starting at positions 9 and 191, respectively. The mouse FMO3 protein sequence was 79 and 82% identical to the human and rabbit FMO3 sequences, respectively. Mouse FMO3 was expressed in Escherichia coli and compared to E. coli expressed human FMO3. The FMO3 proteins migrated with the same mobility ( approximately 58 kDa) as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The expressed FMO3 enzymes (mouse and human forms) were sensitive to heat and reacted in a similar manner toward metal ions and detergent. Catalytic activities of mouse and human FMO3 were high toward the substrate methimazole; however, in the presence of trimethylamine and thioacetamide, FMO-dependent methimazole oxidation by both enzymes was reduced by greater than 85%. Other substrates which inhibited methimazole oxidation were thiourea and thiobenzamide and to a lesser degree N,N-dimethylaniline. When probed with mouse FMO3 cDNA, FMO3 transcripts were detected in hepatic mRNA samples from female mice, but not in samples from males. FMO3 was detected in mRNA samples from male and female mouse lung, but FMO3 message was not detected in mouse kidney sample from either gender. Results of immunoblotting confirmed the tissue- and gender-dependent expression of mouse FMO3.}, number={1}, journal={ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS}, author={Falls, JG and Cherrington, NJ and Clements, KM and Philpot, RM and Levi, PE and Rose, RL and Hodgson, E}, year={1997}, month={Nov}, pages={9–18} }
 @article{falls_ryu_cao_levi_hodgson_1997, title={Regulation of mouse liver flavin-containing monooxygenases 1 and 3 by sex steroids}, volume={342}, ISSN={["0003-9861"]}, DOI={10.1006/abbi.1997.9965}, abstractNote={Based on enzyme activity, protein levels, and mRNA levels, we have previously demonstrated the female-predominant, female-specific, and gender-independent expression in mouse liver of FMO forms 1, 3, and 5, respectively. This study investigated the roles of testosterone, 17 beta-estradiol, and progesterone in the regulation of hepatic FMOs. FMO expression was examined in gonadectomized CD-1 mice, normal CD-1 mice receiving hormonal implants, and gonadectomized mice receiving various hormonal treatments. Following castration of males, hepatic FMO activity levels were significantly increased and serum testosterone levels significantly decreased; however, administration of physiological levels of testosterone to castrated animals returned FMO activity and testosterone concentrations to control levels. When sexually intact and ovariectomized female mice were treated with testosterone, their hepatic FMO activity levels were reduced to those of their male counterparts, concomitant with high serum testosterone levels. In males, castration dramatically increased FMO3 and FMO1 expression, and testosterone replacement to castrated males resulted in ablation of FMO3 expression. In addition, testosterone administration to females (sexually intact and gonadectomized animals) reduced FMO1 expression and obviated FMO3 expression. In females, ovariectomy alone slightly reduced FMO activity, indicative of a possible stimulatory role of female sex steroids; however, female FMO isozyme expression was relatively unchanged, and hormone replacement therapy to ovariectomized females had no discernible effect. In males and females, FMO5 levels were unaffected by gonadectomy or hormone administration, thus indicating a sex hormone-independent mechanism of regulation for this isoform. Interestingly, FMO1 protein levels were increased in sexually intact males following treatment with 17 beta-estradiol; however, only a slight increase in FMO3 protein level was observed. No positive hormone effectors of female FMO expression were identified.}, number={2}, journal={ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS}, author={Falls, JG and Ryu, DY and Cao, Y and Levi, PE and Hodgson, E}, year={1997}, month={Jun}, pages={212–223} }