17α-Ethynylestradiol alters the peritoneal immune response of gilthead seabream.

17α-Ethynylestradiol (EE2), a synthetic estrogen used in most oral contraceptives pills and hormone replacement therapies, is found in many water bodies, where it can modulate the fish immune response. EE2 acts as an endocrine disruptor in gilthead seabream, Sparus aurata L., a marine teleost fish of great economic value in Mediterranean aquaculture, as it induces hepatic vitellogenin gene (vtg) expression. Moreover, EE2 also alters the capacity of gilthead seabream to appropriately respond to infection although it does not behave as an immunosuppressor. Nevertheless, these previous studies have mainly focused on the head kidney leukocytes and no information exists on peritoneal leukocytes, including mast cells. In the present work, juvenile gilthead seabream fish were fed a pellet diet supplemented with EE2 for 76 days and intraperitoneally injected with hemocyanin plus imject alum adjuvant at the end of EE2 treatment and 92 days later, and the peritoneal immune response was analyzed. EE2 supplementation induced vtg expression but returned to basal levels by 3 months post-treatment. Interestingly, gilthead seabream peritoneal leukocytes express the genes encoding for the nuclear estrogen receptor α and the G protein-coupled estrogen receptor 1 and the dietary intake of EE2 induced these expression. Moreover, EE2 induced an inflammatory response in the peritoneal cavity in unvaccinated fish, which was largely maintained for several months after the cessation of the treatment. However, the impact of EE2 in vaccinated fish was rather minor and transient. Taken together, the study provides fresh information about endocrine immune disruption, focusing on peritoneal leukocytes.

In vitro treatments for the theront stage of the ciliate protozoan Cryptocaryon irritans.

The ciliate protozoan Cryptocaryon irritans Brown, 1951, the 'marine white spot', causes one of the most important parasitic fish diseases, with extensive losses every year in mariculture and in the ornamental fish industry. In the present study, we explore the in vitro use of 8 different compounds against the theront (infective) stage of C. irritans; these compounds include extracts of natural products (epigallocatechin gallate (EGCG), L-DOPA, papain), peracetic acid-based compounds (Proxitane 5:23 and 15% peracetic acid, PAA), quinine-based compounds (quinacrine hydrochloride and chloroquine diphosphate) and hydrogen peroxide. All of these compounds had an effect on theront survival; however, only EGCG caused significant theront mortality when applied in doses > or =50 mg l(-1) and over a period of 3 h; papain caused a maximum theront mortality of <50%. We discuss the type of application and potential utility of the compounds tested as part of a management control strategy for C. irritans infections in marine aquaculture and the ornamental fish industry.

Natural and synthetic estrogens modulate the inflammatory response in the gilthead seabream (Sparus aurata L.) through the activation of endothelial cells.

Sex steroids are known to deeply alter processes other than fish reproduction, including fish growth, intermediary metabolism, osmoregulation and immunity. We have previously reported that 17ß-estradiol (E(2)), the main fish estrogen, promotes the mobilization of acidophilic granulocytes from the head kidney, the bone marrow equivalent in fish, to the gonad in the bony fish gilthead seabream (Sparus aurata L.). The aim of this study was to investigate the effects of E(2) and 17α-ethinylestradiol (EE(2)), an endocrine disruptor with strong estrogenic effects commonly found in the aquatic environment, on the ability of gilthead seabream endothelial cells (ECs) to promote leukocyte infiltration. E(2) and EE(2) were seen to affect ECs in different ways. Thus, E(2) was able to increase the production of nitric oxide (NO) and up-regulate the expression of the key activation markers, interleukin-1ß, CC chemokine ligand 4, interleukin-8, E-selectin and matrix metalloproteinase 9, when used alone or combined with bacterial DNA. In contrast, EE(2) failed to affect NO release and reduced the up-regulation of the above genes promoted by bacterial DNA. Moreover, we found that leukocyte adhesion to ECs was enhanced by E(2) treatment. Collectively, these results suggest that estrogens modulate fish leukocyte trafficking during an inflammatory process by activating ECs.

Posthatch development of the axial musculature of the common dentex Dentex dentex, L (Teleostei).

The common dentex is a promising candidate for Mediterranean aquaculture. The present work is aimed at describing the development of the axial musculature from hatching to postlarval life. Transmission electron microscopy, histochemical (NADH-TR and mATPase) and immunohistochemical techniques (S-58 and TUNEL) have been used. At hatching superficial red and deep white muscles can be distinguished. Presumptive dermomyotome (external) cells are initially located over the superficial red muscle but shortly (2 days) tend to concentrate towards the epaxial and hipaxial limits of the myotome. Then, these cells enter the myotome and spread around and within the white muscle thus being apparently responsible for the stratified hyperplasia of the myotome. Mosaic hyperplasia is activated during the second half of the larval period and initially relies on differentiation of a population of atypical premyoblastic cells (APC). APC are mononuclear cells with euchromatic nuclei, cytoplasms full of thin longitudinally projected tubules, occasional mitochondria and scattered ribosomes. By the end of the larval period these cells tend to disappear, partly due to apoptosis, but postlarval mosaic hyperplasia continues by differentiation of presumptive myosatellite cells. APC are an unexpected and singular finding of this study which deserves more research, so as to further characterize their ancestry, developmental programme and fate. In addition to the white and superficial red muscle fibres, intermediate (pink) and tonic fibres appear during larval metamorphosis. Later, during the early postlarval life, a new type of slow twitch red muscle fibre is differentiated (red adult type).