Reproductive Consequences of Exposure to Waterborne Phytoestrogens in Male Fighting Fish Betta splendens

Abstract

Phytoestrogens are plant compounds that can act as endocrine disruptors in vertebrates. Biologically active levels of phytoestrogens have been found in aquatic habitats near wood pulp and paper mills, biofuel manufacturing plants, sewage-treatment plants, and agricultural fields. Phytoestrogens are known to cause hormonal and gonadal changes in male fish, but few studies have connected these effects to outcomes relevant to reproductive success. In one experiment, we exposed sexually mature male fighting fish Betta splendens to environmentally relevant (1 μg L(-1)) and pharmacological concentrations (1000 μg L(-1)) of the phytoestrogen genistein as well as to a positive control of waterborne 17β-estradiol (E2; 1 μg L(-1)), and a negative control of untreated water. In a second experiment, we exposed male B. splendens to environmentally relevant concentrations (1 μg L(-1)) of genistein and β-sitosterol singly and in combination as well as to the positive and negative controls. All exposures were 21 days in duration. We measured sex-steroid hormone levels, gonadosomatic index (GSI), sperm concentration and motility, and fertilization success in these fish. We found that exposure to genistein did not affect circulating levels of the androgen 11-ketotestosterone or the estrogen E2 relative to negative-control fish. We also found that neither of the compounds nor their mixture affected GSI, sperm concentration or motility, or fertilization success in exposed fish relative to negative-control fish. However, fish exposed to phytoestrogens showed some evidence of fewer but more motile sperm than fish exposed to the positive control E2. We conclude that sexually mature male B. splendens are relatively immune to reproductive impairments from short-term exposure to waterborne phytoestrogens.

Contribution of the CASA system, based on open source software, to the assessment of sperm characteristics: informetric and usage-based approaches

“…Several articles evaluated both CASA parameters and the final product of reproduction such as fertilization or hatching rates Stevenson et al, 2011;Fauvel et al, 2012;Kalbassi et al, 2013;Beirão et al, 2014;Immerman and Goetz, 2014;Sanches et al, 2014;Chalde et al, 2016); however, only one study attempted blending this information (Smith, 2012). Smith (2012) evaluated the relationships between sperm viability, velocity, and storage on siring success in Xiphophorus nigrensis.…”

Exposure to Environmentally Relevant Concentrations of Genistein during Activation Does Not Affect Sperm Motility in the Fighting FishBetta splendens

“…The testes were then punctured 40 times with a needle to release the sperm. This method has been used successfully in several previous studies on sperm motility in B. splendens [13, 22]. …”

“…These fish were divided among four treatments: a negative control (no genistein in activation water), a positive control (100  μ M gadolinium), an environmentally relevant dose of 3.7 nM genistein, or a pharmacologic dose of 3.7  μ M genistein [14, 22, 30]. Each treatment group had 10 fish, except the 3.7 nM genistein group, which had 11 fish.…”

“…Sperm motility and concentration decreased in a dose-dependent manner in rainbow trout, Oncorhynchus mykiss , fed diets experimentally enriched with genistein, an isoflavone [18]. Stevenson et al [22] exposed male fighting fish to waterborne genistein and β -sitosterol (a phytosterol) at environmentally relevant and pharmacological concentrations for four weeks but found that neither dose of either phytoestrogen had an effect on sperm quality. Sharpe et al [23] found that β -sitosterol disrupted transcription of steroidogenic acute regulatory (StAR) protein in goldfish, Carassius auratus , which could interfere with steroidogenesis.…”

Case study with natural substances on the various options to identify and categorise endocrine disruptors

“…Further investigations in zebra fish confirm an estrogenic activity of genistein [19]. Other investigations point only to limited effects of genistein on reproductive parameters and hormone levels in fish [20][21][22].…”