In recent studies, both diesel exhaust (DE) and diesel exhaust particles (DEP) have been reported to exert toxic effects on both the male and female reproductive systems. These compounds suppress spermatogenesis in mice 7) and rats 8) ; in one study, serum testosterone levels and the weights of accessory sex glands increased significantly in F344 male rats exposed to DE for 8 months.9) In addition, pregnant C57BL mice injected with diesel exhaust particulate extract (DEPE) showed a significant increase in the rate of abortions, 10) and DEPE increases the uterine weight and myometrial contractility in this strain of mice.11) These results suggest that chemical substances present in diesel exhaust emission cause disturbance of endocrine systems. Meek 12) reported that dichloromethane extracts of DEP could act as activating ligands for estrogen receptors, and Taneda et al. 13,14) reported that crude DEP, as well as successively extracted hexane, benzene, dichloromethane, and methanol fractions, showed estrogenic activity on hER-yeast screen assay. Mori et al. 15) reported that 4,6-and 2,8-dimethyldibenzothiophenes isolated from DEP had estrogenic activity in hER-yeast assay. However, the specific compound that is responsible for this phenomenon remains unclear.We recently isolated the nitrophenol derivatives 4-nitrophenol, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol from DEP and showed that they had vasodilatory activity. 16,17) These compounds captured our attention because it has long been known that alkylphenols are associated with estrogenic activity.2,4) In receptor-binding studies, alkylphenols have been shown to interact directly with the estrogen receptors of rainbow trout and to act in an identical way to 17b-estradiol (E 2 ) in stimulating receptor transcription.2) Furthermore, some estrogenic compounds are known to possess anti-androgenic activity.18) Thus the alkylphenols of DEP are likely to be associated with both estrogenicity and anti-androgenicity.We threrfore evaluated the estrogenic and anti-androgenic activity of the nitrophenols with alkylphenolic structures that we had previously isolated from DEP. MATERIALS AND METHODS ReagentsWe purchased 4-nitrophenol (PNP), 2-methyl-4-nitrophenol (4-nitro-o-cresol, PNOC), and 3-methyl-4-nitrophenol (4-nitro-m-cresol, PNMC) from Tokyo Kasei Kogyo Co. Ltd. (Tokyo, Japan), and we synthesized the 4-nitro-3-phenylphenol (PNMPP) by the method described previously. 17)All other reagents used were of the purest grade commercially available.Human Estrogen Receptor and Human Androgen Receptor Yeasts Human estrogen receptor (hER)-yeast and human androgen receptor (hAR)-yeast were kindly provided by Prof. John P. Sumpter of Brunel University, Uxbridge, U.K. These strains were developed in the Genetics Department at Glaxo Wellcome, plc. (Stevenage, Herts, U.K.).The DNA sequences of either hERa or hAR were integrated stably into the genome of a strain of the yeast Saccharomyces cerevisiae. The yeast also contained expression plasmids ca...

To detect as yet unidentified cell-surface molecules specific to hematopoietic stem cells (HSCs), a modified signal sequence trap was successfully applied to mouse bone marrow (BM) CD34−c-Kit+Sca-1+Lin− (CD34−KSL) HSCs. One of the identified molecules, Endomucin, is an endothelial sialomucin closely related to CD34. High-level expression of Endomucin was confined to the BM KSL HSCs and progenitor cells, and, importantly, long-term repopulating (LTR)–HSCs were exclusively present in the Endomucin+CD34−KSL population. Notably, in the yolk sac, Endomucin expression separated multipotential hematopoietic cells from committed erythroid progenitors in the cell fraction positive for CD41, an early embryonic hematopoietic marker. Furthermore, developing HSCs in the intraembryonic aorta-gonad-mesonephros (AGM) region were highly enriched in the CD45−CD41+Endomucin+ fraction at day 10.5 of gestation (E10.5) and in the CD45+CD41+Endomucin+ fraction at E11.5. Detailed analyses of these fractions uncovered drastic changes in their BM repopulating capacities as well as in vitro cytokine responsiveness within this narrow time frame. Our findings establish Endomucin as a novel cell-surface marker for LTR-HSCs throughout development and provide a powerful tool in understanding HSC ontogeny.

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We recently isolated 3-methyl-4-nitrophenol (4-nitro-m-cresol; PNMC) and 4-nitro-3-phenylphenol (PNMPP) from diesel exhaust particles (DEP) and identified them as vasodilators and xenoestrogens. The estrogenic activity of PNMC and PNMPP was further examined by using immunohistochemical staining of proliferating cell nuclear antigen (PCNA) in uterine luminal epithelium of ovariectomized 25-d-old immature female rats injected with PNMC and PNMPP subcutaneously for 2 d. Significant increases were observed in uterine luminal epithelium in PCNA positive cells of animals receiving 10 and 100 mg/kg PNMC and 0.1 mg/kg PNMPP compared with controls. These results clearly show the estrogenic activity of PNMC and PNMPP by cell proliferation on the uterine luminal epithelium.