A new homolog of FocA transporters identified in cadmium-resistant Euglena gracilis.

To better understand the cellular mechanism of stress resistance to various pollutants (cadmium, pentachlorophenol), we undertook a survey of the Euglena gracilis transcriptome by mRNA differential display and cDNA cloning. We performed a real-time RT-PCR analysis upon four selected genes. One of them significantly changed its expression level in response to stress treatments: B25 gene was overexpressed in Cd-resistant cells whereas it was down-regulated in PCP-adapted cells. By Race assays we obtained for B25 a 1093bp cDNA. The deduced protein was identified as a bacterial formate/nitrite transporter (FocA) homolog and the gene was named EgFth. From all the data, we concluded that EgFth overexpression was related to chronic exposure to cadmium.

Constitutive overexpression of immunoidentical forms of PCP-induced Euglena gracilis CYP-450.

Environmental pollutants are classically associated with increased drug metabolism. In this report, antibodies that are able to detect mammalian CYP proteins, namely the CYP1A1, CYP1A2, CYP2B1/B2, and CYP3A4 proteins, were used to investigate the expression of CYP-related proteins in Euglena gracilis (EG) cells under normal and PCP-treated conditions and in a EG-cell line adapted to PCP. Compared to normal conditions, the presence of PCP in the culture medium induced elevated levels of EG CYP-like proteins. With the exception of CYP3A4, this overexpression was correlated with expression of additional forms of CYP proteins having, respectively, the same molecular weight but slightly different pIs. Even in EG cells which had lost their PCP-adapted property after having been cultured without PCP, these additional forms were continuously expressed. This observation raised the question about the definition of a biomarker of pollution.