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We have previously documented the presence of progesterone and androstenedione in the water column and bottom sediments of the Fenholloway River, Taylor County, Florida. This river receives paper mill effluent and contains masculinized female mosquitofish. We hypothesized that plant sterols (e.g., ss-sitosterol) derived from the pulping of pine trees are transformed by bacteria into progesterone and subsequently into 17alpha-hydroxyprogesterone, androstenedione, and other androgens. In this study, we demonstrate that these same androgens can be produced in vitro from the bacterium Mycobacterium smegmatis. In a second part to this study, we reextracted and reanalyzed the sediment from the Fenholloway River and verified the presence of androstadienedione, a delta1 steroid with androgen activity.

The objective of this study was to evaluate the effects of bleached/unbleached kraft mill effluents (B/UKME) on the reproductive parameters of free-ranging Florida largemouth bass (Micropterus salmoides floridanus). The reproductive parameters measured included gonadosomatic index (GSI), histological evaluation of gonads, and plasma concentrations of vitellogenin (VTG), 17beta-estradiol, and 11-ketotestosterone (11-KT). Hepatic ethoxyresorufin-O-deethylase (EROD) activity was measured as a marker of exposure to cytochrome P450-inducing agents in these effluents. Endpoints were compared among adult bass sampled from tributary and mainstream effluent-contaminated and reference sites. Females sampled from the site closest to the mill outfall had a significant five-fold increase in EROD activity compared to bass sampled from reference streams. Although sex hormones were significantly reduced in bass from exposed sites, there were no differences in VTG and GSI across sites. The absence of organism-level responses was probably not related to a lack of sensitivity, as previous studies in our laboratory have shown that bass exposed to these effluents exhibit changes in GSI and in other measures associated with reproductive success. In females, inverse relationships were observed between VTG and GSI and EROD activity. These relationship, however, were not consistent within all of the sites studied. Collectively, our findings indicate that hepatic EROD induction is an effective marker of B/UKME exposure in largemouth bass and that it might be associated with antiestrogenic effects in this species.