The innovative CALUX® cells have been tailored so that they produce light in a dose-responsive way when exposed to the chemicals.

The switch that turns the light on is specific to compounds or groups of compounds that have the same mode of action. This provides the specific CALUX® assay a selectivity and biological relevance that cannot be matched by instrumental techniques.

The compounds binding to the so-called Ah-receptor is followed by transportation of the PHAH-Ah receptor complex into the nucleus of the cell and subsequent binding to specific sequences in the DNA. These specific DNA sequences are called responsive elements (REs). Binding of the chemical-receptor complex to the RE triggers the expression of RE associated genes. The toxicological impact of the chemicals starts with the observed change in gene expression.

Examples of CALUX® Assays

Dioxins

From 1 July 2002, the European Union set maximum limit values for dioxins in food and feed. Dioxins are one of the most toxic man-made compounds known and can be measured with the DR CALUX®. The DR CALUX® technology is being used as a rapid, sensitive and cost-effective tool for screening food and feed ingredients for dioxin and dioxin-like compounds. Traditional instrumental techniques such as GCMS and HRGCMS can only analyse one sample at a time, making them comparably slow and expensive and not suitable for screening large numbers of samples rapidly.

 

Estrogens

Estrogens like estradiol, a female sex hormone, have a direct effect on the function of the reproductive system, the nervous system, the cardiovascular system and the skeletal system. Blood sugar levels, skin and other tissues and functions are also significantly influenced by estradiol. Like all steroid hormones, excessive amounts of estradiol can contribute to a number of increased health risks. Estrogen level can be measured by the ER CALUX®.

Measuring CALUX® Assays

The technique is performed on 96-well plates, making it possible to analyze a large number of samples simultaneously.

  1. After sample collection, a simple extraction method is used to extract the chemical content.
  2. The extract is purified and fractionated on request. The purified extract is then dissolved in DMSO. Meanwhile, BDS' CALUX® cells are cultured and finally grown in 96-well plates under standardized conditions.
  3. Once a confluent monolayer is obtained, the cells are exposed to the diluted cleaned extracts.
  4. After lysation and adding luciferin, the luciferase activity is quantitated using a luminometer.

Recommended Microplate Readers for CALUX® assays

The Centro XS³ LB 960 "Reporter Gene" model (46970-50) with 2 automatic reagent injectors and waste pump is recommended for this application. The Mithras² LB 943 and Tristar² LB 942 multimode readers with luminescence module and 2 injectors are also suitable.

CALUX® is a registered trademark of BioDetection Systems B.V.