Hepatic expression of metal-related genes and gill histology in sand flathead (Platycephalus bassensis) from a metal contaminated estuary

Hepatic gene expression and gill histology were measured in sand flathead (Platycephalus bassensis) from a metal polluted estuary. The gene expression analyses were conducted on fish from two most polluted sites and a reference site. The metal-related genes were metal-regulatory transcription factor 1 (MTF1), transferrin (TF), ferriportin1 (FPN1), ferritin and metallothionein. The transcripts of MTF1, TF, and FPN1 were significantly higher in the liver of fish caught at polluted sites, suggesting these genes are potential biomarkers for environmental exposure to metal. Strong correlations were found between the transcripts of these three genes. Four types of gill lesions such as hyperplasia and lamellar fusion, epitheliocystis, telangiectasis, and deformed filament were observed in sampled fish. There was significant difference in the prevalence of epitheliocystis and telangiectasis between the fish from the polluted areas and reference area. Gill parasites were less prevalent in the flathead from polluted sites. The gill histopathological results indicated both pollutants and infections could contribute to gill lesions.