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Influence of acidic pH, aluminum and manganese on reproductive physiology of Astyanax bimaculatus males (Characiformes: Characidae)

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Author(s):
Bianca Mayumi Silva Kida
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Biociências
Defense date:
Examining board members:
Renata Guimarães Moreira Whitton; Maria Ines Borella; Flavia Pinheiro Zanotto
Advisor: Renata Guimarães Moreira Whitton
Abstract

Metals can cause adverse wide range effects on reproductive function of animals, mostly in aquatic organisms. They can alter the endocrine system, acting on gonadal steroidogenesis, affecting the reproductive process of fish. We aimed to investigate the effects of the metals aluminum (Al) and manganese (Mn) in acidic pH on the steroidogenesis of Astyanax bimaculatus males, sexually mature, after an acute exposure of 96 hours and evaluate if the animals were able to recover of the possible effects of these metals in the water free of metals. Mature males were exposed to a concentration of 0.5 mg.l-1 of Al and Mn (isolated or combined) and the experimental groups were maintained at acidic pH (5.5) to keep the metals bioavailable. We performed an acute exposure of 96 hours, with samplings at 24h and 96h, and then also a period of 96h in water free of metals, with samplings at 120h and 192h from the beginning of the experiment. We measured the plasma levels of testosterone (T), 11-ketotestosterone (11-KT), 17?-estradiol (E2) and cortisol (C) by elisaimmunoassay. Furthermore, histological analysis of testes and evaluation of the sperm concentration were performed. The metals studied, in addition to acidic pH, were able to alter the plasma concentration of the androgens T and 11KT. A transitory increase (24h) of E2 levels was also observed, but only in animals exposed to Mn and then a decrease in 96h occurred. Exposure to acidic pH and metals, alone or combined did not trigger changes in C plasma levels. Generally, Al and Mn as well as the acidity of water can act as endocrine disruptor in A. Bimaculatus males, mainly by stimulating the androgens synthesis, causing changes on physiological system. However, 96 hours in water free of metals were not enough for the animals to recover from the effects of the metals. The testes were in the advanced stage of maturation, while sperm concentration was not significantly changed to suggest any influence of metals together with acidic pH in altering this variable. Reproductive tactic could be used by the species to trigger changes in testicular steroidogenesis, mainly accelerating the process of spermatogenesis and spermiogenesis, what may interfere with the reproductive dynamics (AU)

FAPESP's process: 11/15056-6 - Effects of exposition of aluminium and manganese on gonad steroidogenesis in males of Astyanax bimaculatus (Teleostei: Characidae)
Grantee:Bianca Mayumi Silva Kida
Support type: Scholarships in Brazil - Master