Accumulation and tolerance to cadmium heavy metal ions and induction of 14-3-3 gene expression in response to cadmium exposure in Coprinus atramentarius

Abstract

Cadmium (Cd), one of the most toxic heavy-metal pollutants, has a strong and irreversible tendency to accumulate. Bioremediation is a promising technology to remedy and control heavy metal pollutants because of its low cost and ability to recycle heavy metals. Coprinus atramentarius is recognized as being able to accumulate heavy metal ions. In this work, C. atramentarius is cultivated on a solid medium containing Cd²⁺ ions to analyze its ability to tolerate different concentrations of the heavy metal ion. It is found that the growth of C. atramentarius is not significantly inhibited when the concentration of Cd²⁺ is less than 0.6mgL^-1. The accumulation capacity of C. atramentarius at different Cd²⁺ concentrations also was determined. The results show that 76% of the Cd²⁺ present can be accumulated even when the concentration of the Cd²⁺ is 1mgL^-1. The different proteins of C. atramentarius exposed to Cd²⁺ were further analyzed using gel electrophoresis. A 14-3-3 protein was identified and shown to be significantly up-regulated. In a further study, a full-length 14-3-3 gene was cloned containing a 759bp open reading frame encoding a polypeptide consisting of 252 amino acids and 3 introns. The gene expression work also showed that the 14-3-3 was significantly induced, and showed coordinated patterns of expression, with Cd²⁺ exposure.

Keywords: 14-3-3; Accumulation and tolerance; Cadmium; Coprinus atramentarius; Heavy metal.