Ugalketako disrupzio endokrinoa Gernika eta Galindoko araztegien inguruko korrokoietan (Chelon labrosus)

Abstract

Disruptore endokrinoak (EDC), ingurugiro-kutsatzaile kezkagarrienetarikoak dira animalien garapen eta ugalketarengan eragin kaltegarria dutelako. EDCetako batzuk eragin xenoestrogenikoa dute, ugal-hormona femenino garrantzitsuena den eta garapen zein ugalketaren arduradun den estrogeno naturala imitatzeko gai direlako. Ur araztegiek xenoestrogenoak isurtzen dituzte ibaietara, arrain arren feminizazioa sortuz. Azken urteetan Gernikako araztegiak isuritako konposatu kimikoen ondorioak ikertu ditugu bertako Chelon labrosus korrokoien populazioan; non barrabiletan obozitoak dituzten arrak (intersex) aurkitu ditugu. Gure azken ikerketetan Gernikako korrokoi populazioaren efektu xenoestrogenikoen balioztatzearekin jarraitzeko asmoz eta, aldi berean Galindoko araztegiaren, Bilbo hiritik ur-behera, eragin posiblea ikertzeko asmoz, C. Labrosus indibiduoak hartu ziren 2013ko ekainean eta 2014ko otsailean. Gonaden ikerketa histologikoak eta xenoestrogenoen aurrean erantzuten duten bitelogenina (vtg) eta cyp19a1a aromatasa geneen transkripzio-mailen analisiak burutu ziren. Beste markatzaile molekular berri batzuk, 5S rRNA eta tfiiia, obozitoen presentziaren adierazgarri direnak ere aztertuak izan ziren. Testikuluetan obozitoak zituzten intersex arrak behatu ziren, bai Gernikan eta bai Galindon. Intersex korrokoiek arrek baino 5S/18S rRNA indizea eta tfiiia transkripzio maila altuak azaldu zituzten, emeen antzekoak. Bi markatzaile molekular hauek korrelazio positiboa adierazi zuten intersex larritasun indizearekin. Ar eta intersexen vtg-ren transkripzio mailak ez zuten desberdintasunik azaldu. Laburbilduz, emaitzek Galindo eta Gernikako korrokoiak kimikari xenoestrogenikoei esposatuta daudela iradokitzen dute.Endocrine disrupting chemicals (EDCs) are among the most concerning environmental pollutants due to their effect on animal developmental and reproduction processes. Some EDCs are considered xenoestrogens because they are able to mimic natural estrogen; the most important reproductive hormone in female vertebrates.Waste water treatment plants (WWTP) discharge xenoestrogen to receiving water masses causing fish feminization. In the last years, the effects of the WWTP effluent from Gernika on the local population of thicklip grey mullets, Chelon labrosus, has been studied and males with oocytes in their testis (intersex) have been identified. With the aim to continue with the assessment of xenoestrogenic effects in the mullet population from Gernika and extend the study to another potential pollution hot-spot, such as the Galindo WWTP (downstream the city of Bilbao) mullets were captured in June 2013 and February 2014. Histological studies of gonads and gene transcription analysis of xenoestrogen responding genes such as vitellogenin (vtg) and cyp19a1a aromatase were performed. Novel biomarkers of presence of oocytes such as 5S rRNA and tfiiia were also assessed transcriptionally. Intersex males which contained oocytes within the testis were observed in Gernika and Galindo. Intersex mullets showed higher 5S/18S rRNA index and tfiiia transcription levels in gonads than males, and similar to females. These two molecular markers showed a positive correlation with the scored intersex severity index. Transcription levels of vtg did not show differences between males and intersex. In summary, results suggest that mullet populations from Galindo and Gernika are exposed to xenoestrogenic chemicals.