86,569 research outputs found
EDCs: Focus on reproductive alterations in mammalian and nonmammalian models
No full textIt is well known that endocrine-disrupting chemicals, thanks to their ability to mimic or antagonize sexual hormone activity, can affect the reproductive functions of both wild animals and humans. Some of them are slow to break down in the environment, making them potentially hazardous over time. Starting in 2000, experts concluded there was credible evidence that very low doses of some hormone-like chemicals can adversely affect bodily functions in test animals. Many studies so far evaluated the endocrine properties of a plethora of chemicals, and in this chapter, attention will be mainly posed to Bisphenol A, its analogs, most common phthalates, and components of flame retardants. All these compounds affect body reproductive tissues in mammalian and nonmammalian species by interacting with the hypothalamic–pituitary–gonadal axis. Results presented within the chapter will help to create a comprehensive database from several scientific studies on how different substances interact with natural hormones and their receptors, thus contrasting or potentiating their physiological effects
Role of substrate on larval development of the freshwater teleost Pelvicachromis pulcher.
No full textTamoxifen as an emerging endocrine disruptor: Effects on fish reproduction and detoxification target genes
No full textExpression of VTG and CYP1A biomarkers in Zosterisessor ophiocephalus sampled in different areas of the Venice Lagoon
No full textThe Venice Lagoon is a transitional environment on the Adriatic
coast influenced by such human activities as agriculture, industry and
tourism. Several studies carried out in the last years have demonstrated
the presence of a wide range of contaminants in the Venice
Lagoon. Biomonitoring in the lagoon environment plays an important
role in strategies and actions to identify, control and reduce the
environmental threats. Biomarkers monitored in this study are VTG
(Vitellogenin) and CYP1A. VTG is produced in the liver of sexually
mature female fish in response to endogenous estrogens. CYP1A
represents the most intensively studied P450 gene in fish and its
expression is induced by a wide variety of lipophilic contaminants. In
the present study we used Western blot and Real Time PCR
techniques to detect the expression of VTG and CYP1A in plasma
and liver of a goby fish, Zosterisessor ophiocephalus, sampled in
different areas of the Venice Lagoon, possibly interested by different
pollution entities. Our results evidenced that VTG expression was
detectable in adult male of Z. ophiocephalus collected from the
different sites evidencing high toxicological risk probably due to
endocrine disrupting chemicals. Moreover, the highest levels of
CYP1A were observed in animals sampled at the Porto Marghera site
showed that this site, which is influenced by the presence of the
industrial area and the city of Venice, is the most highly impacted
area of the lagoon. VTG and CYP1A induction in fish can be useful
biosensors for environmental pollution monitoring
Modulation of the hepatic CYP1A1 system in the marine fish Gobius niger, exposed to xenobiotic compounds.
No full textAnthropogenic chemicals in the aquatic environment are known to cause reproductive disturbances in vertebrate and invertebrate organisms by interfering with the endocrine systems. Large efforts have recently been devoted to dissect the mechanisms of action of xenobiotics in aquatic species, with the ultimate aim of detecting and controlling the effects of chemical exposure on the aquatic ecosystem and humans. In the present paper, males of a marine species, the black goby (Gobius niger), were treated with estrogenicand dioxin-like compounds commonly discharged into the environment from industry, agriculture, and urban waste such as nonylphenol (NP) and beta-naphthoflavone (beta-NF). Their effects were compared with those induced by estradiol (E2), analyzing the expression of biomarkers commonly used in ecotoxicological studies such as vitellogenin (VTG) and cytochrome P4501A1. The treatment with NP induced the synthesis of the female specific protein VTG in males, showing its estrogenic activity. NP and E2 lowered cytochrome P4501A1 basal levels while beta-NF determined a significant rise of its expression. The detoxification pathway was investigated,and the most relevant finding of this paper was the evidence that cytochrome P4501A1 inhibition by estrogen and estrogen-like compounds is mediated through the activation of the aryl hydrocarbon receptor repressor
Role of cathepsins in ovarian follicle growth and maturation
No full textSeveral complex processes are involved in the production of viable eggs. The aim of this review is to provide an overview on the role played by lysosomal enzymes, especially cathepsins B, D, and L, during ovarian follicle growth and maturation. Specific attention is focused on the relationship between the second proteolytic cleavage of yolk proteins (YP) and the resumption of the meiosis during germinal vesicle break down (GVBD). Maturation represents the final stage of oocytes development prior to ovulation. Oocytes in this phase appear translucent. In many teleosts GVBD is accompanied by water uptake and among marine teleosts with pelagic eggs, most of the final volume is reached by this process. The last phase of maturation in benthonic eggs also occurs concomitant to a second proteolytic cleavage and is related with a slight hydration process. In vitro maturation by 17α,20β-dihydroxy-4-pregnen-3one in class III Danio rerio oocytes, induced 80% of GVBD. The maturation of these oocytes is known to be associated with proteolysis of their major yolk components. In the present study, we show that inhibition of specific enzymes (cathepsins) involved in the second YP processing, did not affect the occurrence of GVBD as the oocytes become translucent and display a slight increase in size. More specifically, in vitro incubation of the maturing oocytes with a cathepsin B inhibitor suppressed both cathepsin B and L activities and the proteolysis of YP. On the contrary, the addition of cathepsin L inhibitor, only affected cathepsin L activity, indicating that cathepsin B is probably involved in Cathepsin L activation, and this enzyme is probably responsible for the second YP processing. These results, together with previous studies, indicate that the GVBD process is independent of the occurrence of the second proteolytic process. It supports the hypothesis that the maturation process is under K+ ion flux control, while yolk proteolysis is related to the temporal and specific activation of cathepsins by acidification of yolk spheres
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