Effects of XXXX exposure on fathead minnow (Pimephales promelas) reproduction and embryonic development.

@entity172 @entity251 @entity5444 @entity2671 @entity53 @entity342 @entity3800
UNASSIGNED: High concentrations (300   ng/L) of @entity2671 (A4) were identified in snowmelt runoff from fields fertilized with manure from livestock feeding operations in Wisconsin, USA. In fishes, A4 is an active @entity342 and substrate for biosynthesis of functional @entity3800 (e.g., @entity251 and @entity5444 ) and @entity172 (e.g., @entity53 -17b). Thus, A4 has the potential to be a powerful endocrine disruptor. This hypothesis was tested by exposing reproductively mature fathead minnows to 0.0   ng/L, 4.5   ng/L, 74   ng/L, and 700   ng/L A4 for 26   d in a flow-through system. Various reproductive endpoints were measured including fecundity, fertilization success, secondary sexual characteristics, gonadosomatic index (GSI), and hepatic vitellogenin messenger RNA (mRNA) expression. In addition, fertilized embryos from the reproduction assay were used in an embryonic development assay to assess A4 effects on development and hatchability. In males, A4 significantly increased Vtg mRNA expression (estrogenic effect), significantly reduced GSI, and had no effect on tubercle expression (p   =   0.067). In females, A4 induced tubercle development (androgenic effect) with no effects on GSI. Fecundity was not significantly impacted. Exposure to A4 had no effect on fertilization, embryonic development, or hatchability. These data indicate that exogenous A4, at environmentally relevant concentrations, can significantly modulate the reproductive physiology of the fathead minnows in a sex-specific manner and that A4 should be monitored as an endocrine disruptor. Environ Toxicol Chem 2015;34:2549-2554.    2015 SETAC.
