Assessment of reproductive stress in natural populations of the fish Aphanius fasciatus using quantitative mRNA markers

2 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona, 18, 08034 Barcelona, Spain ABSTRACT: Four populations of the Mediterranean killifish Aphanius fasciatus were studied to evaluate the biological effects of environmental pollution. These effects were measured using RNA quantification-based markers in the gonads and liver. Metallothionein genes in both testes and ovaries showed elevated expression in males and females from the more contaminated areas. In addition, males from these areas showed elevated levels of vitellogenin synthesis in the liver. These results were correlated with heavy metals and polycyclic aromatic hydrocarbon levels in water and sediment samples from the sampling sites. They represent the first evidence of an incipient feminization of marine fish along the coast of Tunisia and confirm the utility of RNA quantification-based markers for monitoring environmental impact on small animals and in species for which very little biological information is available.