BIOASSAY OF SELENIUM

摘要

The invention relates to a plasmid carrying a selenium-specifying DNA sequence of the E. coli fdhF gene upstream the E. coli lac'Z gene which permits the incorporation of selenocystein into beta -galactosidase. Particular plasmids according to the invention are pRM2, deposited at the ATCC under No. 75594 and pRM4, deposited at the ATCC under No. 75595. The invention also relates to micro-organisms transformed with a plasmid according to the invention having selenium-dependent beta -galactosidase activity. The invention provides a method for the quantitative determination of selenium in selenium derivatives in a biological sample comprising incubating micro-organisms according to the invention in a suitable medium also containing said sample and measuring the level of beta -galactosidase activity. The biological sample may be, e.g. a blood sample or a food sample.