ABSTRACT
The technology of molecular genetics has revolutionized research in a large number of fields, including developmental toxicology. It is possible to directly address questions about the effect of xenobiotic chemicals on the expression and function of the genes controlling development. Deoxyribonucleic acid (DNA) is the genetic material of cells. It encodes all of the information specifying the primary structure of all proteins in the organism. DNA is a double-stranded polymer. The genes in prokaryotic organisms are arranged in a continuous linear fashion such that the DNA sequence corresponds directly to the m-ribonucleic acid (mRNA) sequence. Libraries of DNA can be constructed from the entire genome of an organism by treating cellular DNA with restriction enzymes. The single most important point to remember is that good results can be obtained only if one is fastidious, particularly when working with RNA. Probes for detecting specific mRNAs can be made of DNA or RNA.
