Fish reproduction

In fish reproduction, the best-investigated pheromone system is that of the goldfish [Carassius auratus). Here, sex steroids and prostaglandins play important roles. The female produces two pheromones sequentially a preovulatory primer pheromone and a postovulatory prostaglandin pheromone that act on the male. 

The olfactory system of the male is extremely sensitive to 17,20jSP. The fish respond to a concentration of 5 x 10 ° mol/1. This amount(3 x 10 molecules) is released by a 90 mm female fish into 1 liter water. The females are also very sensitive to 17,20/3P. It may stimulate ovulation. Of 47 vitellogenic females 13 ovulated when 17,20/3P was added to the water, while only 1 of 43 did so in untreated water (Dulka etal, 1987). Both sexes probably release 17,20/3P. Ecologically, this bisexual pheromone is thought to synchronize milt production with ovulation and thus coordinate spawning in local populations (Dulka etal, 1987 Sorensen and Stacey, 1990). 

At the time of ovulation - which is about 12 hours after onset of the gonadotropin II surge in the female - females release less pheromonal steroids than before. They now become sexually active, receptive, and attractive to males. 

These phenomena result from the hormonal function of prostaglandin F20, which is produced by the female, and released via urine and across the gill. It stimulates follicular rupture and female spawning. The ovulated eggs are in the oviduct for several hours. During that time they stimulate a 100-fold rise in blood levels of prostaglandin V2a- 

Female rainbow trout, Oncorhynchusmykiss, also release in their urine 17,20jSP. As in goldfish, this pheromone increases the plasma levels of gonadotropin II and testosterone in spermiating males Scott etal, 1994). Levels of 17,20jSP rises within 1 hour of exposure and peak at 3-4 hours. Milt production also increases (Vermeirssenetfl /., 1997). 

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Apart from the wide range of neurotoxic and behavioral effects caused by OPs, many of which can be related to inhibition of AChE, other symptoms of toxicity have been reported. These include effects on the immune system of rodents (Galloway and Handy 2003), and effects on fish reproduction (Cook et al. 2005 Sebire et al. 2008). In these examples, the site of action of the chemicals is not identified. Indirect effects on the immune system or on reproduction following initial interaction with AChE of the nervous system cannot be ruled out. It is also possible that OPs act directly on the endocrine system or the reproductive system, and phosphorylate other targets in these locations (Galloway and Handy 2003). 

Negative externalities arise when an action by an individual or a group implies harmful effects on others such as unintended dispersion of chemicals to land, air and water air pollution effects on health forest growth or fish reproduction. When negative externalities are generated they should be internalized into the market economy. By internalizing the externalities the economic value of environmental impacts are allocated to the pollution sources and included in the economics of the activities causing the problem. This would also allow for the market to function properly and thereby reach a socially optimal level of environmental impacts. 

Adverse effects on fish reproduction possible Fish Diet Freshwater fishes >2 pg inorganic Se/L >1 pg organic Se/L sometimes, <1 pg organic Se/L 42... 

Neilson, A. H., Allard, A-S., Reiland, S., Remberger, M., Tarnholm, A., Victor, T. Lendner, L. (1984). Tri- and tetrachloroveratrole, metabolites produced by bacterial O-methylation of tri- and tetrachloroguaiacol an assessment of their bioconcentration potential and their effects on fish reproduction. Canadian Journal of Fisheries and Aquatic Science, 41, 1502-12. 

Congener 126 is the most potent of the PCBs in binding to the AHH receptor of fish [57]. A number of studies demonstrated the correlation between organic contaminant levels and fish reproductive effects, but specific mechanisms were not identified [58-60] it was assumed that PCBs and PCDD/Fs were the causative contaminants. Wilson et al. [61] demonstrated that fish eggs injected with Lake Michigan lake trout extract exhibited embryonic toxicity. 

Koshelev, B.V. (1984). Ecology of Fish Reproduction (In Russian). Nauka, Moscow, 309 pp. 

Shekk, P.V. (1983). On the energy metabolism and food rations of grey mullet during wintering (In Russian). In The Physiological Foundations of Marine and Diadromous Fish Reproduction (J.A. Shelkanova, ed.), pp. 81-85. Legkaya i Pishchevaya Promyshlennost, Moscow. 

Van Look, K.J.W. (2001) The development of sperm motility and morphology techniques for the assessment of the effects of heavy metals on fish reproduction. PhD Thesis, University of Sheffield, Sheffield. 

Arukwe, A. Cellular and molecular responses to endocrine-modulators and the impact on fish reproduction. Mar. Pollut. Bull. 42 643 -655, 2001. 

Acknowledgements. This publication was made possible by grants from the National Institute of Environmental Health Sciences, NIH (P42 ES 07375), NIH (1R43 ES011882-01) and NSF (BES-9906060). The contents are solely the responsibility of the authors and do not necessarily represent the official views of NIEHS or NSF. The authors wish to acknowledge technical help from Marjorie Chow and Ben O Neal for the 2D gel of largemouth bass, Kevin Kroll for his advice on fish reproduction and Barbara Carter for the subtractive hybridizations. 

Flouriot, G., F. Pakdel, B. Ducouret, Y. Ledrean and Y. Valotaire. Differential regulation of two genes implicated in fish reproduction vitellogenin and estrogen receptor genes. Mol. Reprod. Dev. 48 317-323, 991. 

What does the presence or level of Vg in the blood or liver of a male fish really tell us Drawing general conclusions about the relationship between Vg induction by an EDC and the consequences of EDC exposure to fish reproductive function is difficult... 

Arcand-Hoy, L.D. and W.H. Benson. Fish reproduction an ecologically relevant indicator of endocrine disruption. Environ. Toxicol. Chem. 17 49-57, 1998. 

Sumpter, J.P. Environmental control of fish reproduction a different perspective. Fish Physiol. Biochem. 17 25-31, 1997. 

Interestingly, although fish reproductive lifestyles are highly diverse, the steroids and F prostaglandins (PGFs) from which hormonal pheromones are derived appear highly conserved. For example, in all fish examined, estradiol-17p (E2) induces vitellogenesis... 

Balon, E.K. 1984. Patterns in the evolution of reproductive styles in fishes. In Fish Reproduction Strategies and Tactics (Ed. by G.W. Potts R.J. Wootton), pp 35-53. London Academic Press. 

Stacey, N.E., Kyle, A.L. Liley, N.R. 1986. Fish reproductive pheromones. In Chemical Signals in Vertebrates 4 (Ed. by D. Duvall, D. Muller-Schwarze R.M. Silverstein), pp 117—134. New York Plenum Press. 

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