Team:HBUT-China/Description
Project Description
For this year's iGEM Competition, our team has focused on putting forward a biological approach to detecting nickel ions as a heavy metal contaminant in the natural environment. Through our study over this summer, we are expecting to control the expression of red fluorescent protein by changing the nickel ion concentration. In a certain concentration range, we will try to establish a quantitative relationship between the intensity of the fluorescence and the concentration of nickel ions in the environment. This may build a nickel ion concentration quantitative detection system.
In order to achieve this goal, we use a nickel-sensitive repressive promoter (pncrA). In the absence of nickel ions, the repressor protein (NcrB) binds to the promoter, preventing the expression of the subsequent gene. The nickel ions in the environment can bind to repressor proteins to alter the domain of the protein, so that the fluorescent protein gene behind the promoter is expressed and produces fluorescence.
How do we come to this idea?
Nickel is an important element for humans. Normally, the human body has a daily requirement of 0.3mg nickel. However, it can cause allergic reactions for an estimated 20% of human beings. And experts claim an intake of more than 0.6mg at a time can cause an allergic reaction in almost any person, while a chronic excessive intake of nickel can cause a variety of toxic reactions, including dermatitis, respiratory disorders and even respiratory cancer. In addition, nickel is also considered to be a relevant factor in causing leukemia, asthma, and urinary stones. Also, it can possibly lead to reduced fertility and teratogenicity.
2、Nickel pollutionNickel pollution generally refers to excessive amounts of nickel existing in the environment that humans are exposed to. Traditionally, major sources of nickel in the environment are the steelmaking and electroplating industries, with approximately 85% of nickel being used in certain of these processes. However, with the rapid development of science and technology, the manufacturing of electronic products has brought a substantial amount of nickel ions to the environment. Also, with the popularity of new energy vehicles, nickel-metal hydride batteries being their major power source has contributed to an increasing demand for nickel, and unavoidably, an increasing amount of nickel ions in the environment as well. Statistics indicate that 2016 global raw nickel consumption reached 200 million tons. The future demand for nickel is predicted to continue increasing at an annual 5% growth rate on average. As a consequence, we may have to anticipate an increase in nickel pollution. Therefore, the detection of nickel ions in the environment and hence methods to alleviate nickel pollution will be vitally important.
3、The drawbacks of existing nickel ion detection methodsCurrently, the most commonly adopted method of nickel ion detection is spectrophotometry, with which nickel ion concentrations can be detected within the range from 0.08 to 5.0 mg / L in solid samples, and from 0.25 to 10 mg / L in water samples. However, spectrophotometry has obvious limitations, being very susceptible to interference from other substances throughout its detection process, thus being a relatively less reliable detection approach. Moreover, the procedures are fairly complicated and costly. Our team is striving to put forward a biological approach for nickel ion detection which can achieve the same accuracy as spectrophotometry yet be simpler in procedures and probably be much lower in cost.
