Effects of the estrogen mimic genistein as a dietary component on sex differentiation and ethoxyresorufin-O-deethylase (EROD) activity in channel catfish (Ictalurus punctatus)

Abstract

A number of aquaculture species, including channel catfish Ictalurus punctatus, are fed high proportions of soybean meal in their diet. We have investigated the potential for the most common phytoestrogen in soybean meal to alter phenotypic sex during sexual differentiation in channel catfish. Channel catfish were fed four dietary concentrations of the phytoestrogen genistein (0, 2, 4, and 8 mg g(-1)) to determine its effect on gonadal sex differentiation. The four treatment diets were fed to sexually undifferentiated channel catfish between 5 and 140 days post hatch (dph) and between 60 and 150 dph. Phenotypic sex was determined by histological examination of the gonads. Ethoxyresorufin-O-deethylase activity was not significantly different among the treatment and control groups. Phenotypic sex was significantly dependant on dietary phytoestrogen concentration (P = 0.01). Additionally, logistic regression showed a significant relation between genistein concentration in the diet and gonadal sex (P = 0.02). Intersex individuals were present at all treatment concentrations, with increasing proportions of intersex fish as the genistein concentration increased for individuals fed treated diets between 5 and 140 dph. Increased proportions of phenotypically male individuals resulted from chronic dietary exposure to the estrogen mimic genistein. There were no significant differences in the proportions of males and females between feed treatment durations. These findings establish that dietary concentrations of genistein can alter sex ratios in cultured channel catfish populations and demonstrates the need to further understand the actions of this and other prominent phytoestrogens in aquaculture species.

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“…Genistein can have both estrogenic and antiestrogenic effects, either of which, in turn, can have stimulatory or suppressive actions on growth and reproduction in fish (Green and Kelly, 2009). In the present study, fish fed genistein supplemented diet showed no significant change in growth (P>0.05) compared to the control fish.…”

“…Genistein was added to finely ground diets (crude protein 35.4%) using 10 ml of a 1:1 mixture of dimethylsulfoxide (DMSO) and ethanol for 1 kg feed (Green and Kelly, 2009) while methanol extract of B. alba was added after dissolving in DMSO only (Moundipa et al, 2005). Control diet was treated with a 1:1 mixture of DMSO and ethanol only.…”

“…Genistein, a well-characterized isoflavone, is an important secondary plant metabolite that has been important secondary plant metabolite that has been reported to be present in soybean meal and pulp mill effluents and exert estrogenic and/or antiestrogenic effects (Green and Kelly, 2009). Besides, attempts have been made to use the therapeutic potential of this isoflavone for growth induction and health promotion in fish (Chakraborty and Hancz, 2011;Chakraborty et al, 2014).…”

Reproductive endocrine disruption in smallmouth bass (Micropterus dolomieu) in the Potomac River basin: spatial and temporal comparisons of biological effects

“…They may enter the aquatic environment from agricultural (Burnison et al 2003; Hartmann et al 2008; Kolpin et al 2010) and industrial sources (Lundgren and Novak 2009) and may disrupt reproductive endocrine function. For example, TO have been induced in fishes through both aqueous (Kiparissis et al 2003) and dietary (Green and Kelly 2009) exposures to selected phytoestrogens.…”

Neoplasia and Neoplasm-Associated Lesions in Laboratory Colonies of Zebrafish Emphasizing Key Infl uences of Diet and Aquaculture System Design

“…A wide variety of natural carcinogens and anticarcinogens in plants and other dietary factors are now well characterized in research focused on optimization of healthy aging (Aiyer et al 2008; Akhtar et al 2009). Recently dietary factors such as trace contamination by arsenic and other metals (Kozul et al 2008) and estrogenic plant components in practical laboratory animal diets (Adlercreutz 2007; Adlercreutz et al 2004; Cross et al 2004; Green and Kelly 2008; Ziegler et al 2004) have been recognized as confounding factors in toxicology and carcinogenesis studies.…”