1,721,004 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
Tamoxifen as an emerging endocrine disruptor: Effects on fish reproduction and detoxification target genes
No full textModulation 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 substrate on larval development of the freshwater teleost Pelvivachromis pulcher.
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Oxidative stress and antioxidant defense in fish: the implications of probiotic, prebiotic and synbiotics
No full textIn fish, like other organisms, the lack of balance between the production of reactive oxygen species (ROS) and antioxidant defense system (so-called oxidative stress) can cause DNA hydroxylation, protein denaturation, lipid peroxidation, apoptosis, and ultimately cell damage. To improve the antioxidant defense capability, different approaches such as the administration of synthetic antioxidants were practiced. During the past years, dietary approaches have been suggested as a promising way of increasing the antioxidant defense activity in different fish and shellfish species. Among them, microbial feed additives (including pre-, pro-, and synbiotics) showed promising effects in terms of affecting antioxidant enzymes activities. Their mechanism of action in influencing the antioxidant system is not fully understood. The present review briefly discussed the antioxidant defense activity in fish, influencing factors with special focus on dietary approaches and microbial feed additives. In addition, the proposed mechanism of action of microbial feed additives on the antioxidant system has been discussed
Role of substrate on larval development of the freshwater Teleost Pelvicachromis pulcher.
No full textA comparison of reproductive performances in young and old females: A case study on the atlantic bluefin tuna in the mediterranean sea
Full text linkIn the Mediterranean Sea, a demographic substructure of the Atlantic bluefin tuna Thunnus thynnus has emerged over the last decade, with old and young individuals exhibiting different horizontal movements and spatial–temporal patterns of gonad maturation. In the present study, histology and molecular reproductive markers were integrated with the gonad-specific mir-202 gene expression and ovarian localization to provide a comprehensive picture of the reproductive performances in young and old females and investigate the role played by the mir-202 during gonadal maturation. During the reproductive period, old females (>100 kg; 194.6 ± 33.9 cm straight fork length; 11.3 ± 2.7 years old) were found to have greater reproductive performances than younger females (<80 kg; 139.3 ± 18.8 cm straight fork length; 8.4 ± 1.1 years old) according to gene expression results, suggesting a prolonged spawning season, earlier arrival on spawning grounds and/or better condition in older females. The mir-202-5p showed no global changes; it was abundantly expressed in granulosa cells and faintly present in the ooplasm. On the other hand, the mir-202-3p expression profile reflected levels of oocyte maturation molecular markers (star, lhr) and both histological and molecular (casp3) levels of follicular atresia. Overall, old females exhibited greater reproductive performances than younger females, likely reflecting different reproductive dynamics linked to the physical condition, habitat usage and migratory behaviour. These results highlight the importance of preserving large and old females in the context of fishery management. Finally, the mir-202 appears to be a good candidate to regulate the reproductive output of this species in an autocrine/paracrine manner through either stage-or age-dependent processes
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