Recombinant DNA
[3][4][5][6] It is one of two most widely used methods, along with polymerase chain reaction (PCR), used to direct the replication of any specific DNA sequence chosen by the experimentalist.
That is, their appearance, behavior and metabolism are usually unchanged, and the only way to demonstrate the presence of recombinant sequences is to examine the DNA itself, typically using a polymerase chain reaction (PCR) test.
[13] Gross phenotypic changes are not the norm, unless the recombinant gene has been chosen and modified so as to generate biological activity in the host organism.
[14] Additional phenotypes that are encountered include toxicity to the host organism induced by the recombinant gene product, especially if it is over-expressed or expressed within inappropriate cells or tissues.
The most common application of recombinant DNA is in basic research, in which the technology is important to most current work in the biological and biomedical sciences.
[4] Many additional practical applications of recombinant DNA are found in industry, food production, human and veterinary medicine, agriculture, and bioengineering.
Found in rennet, chymosin is the enzyme responsible for hydrolysis of κ-casein to produce para-κ-casein and glycomacropeptide, which is the first step in formation of cheese, and subsequently curd, and whey.
Traditionally, processors obtained chymosin from rennet, a preparation derived from the fourth stomach of milk-fed calves.
[26] Recombinant antibodies (rAbs) are produced in vitro by the means of expression systems based on mammalian cells.
Their monospecific binding to a specific epitope makes rAbs eligible not only for research purposes, but also as therapy options against certain cancer types, infections and autoimmune diseases.
The DNA test looks for the presence of HIV genetic material using reverse transcription polymerase chain reaction (RT-PCR).
[14] This variety of rice holds substantial promise for reducing the incidence of vitamin A deficiency in the world's population.
[28] The bacterium has been applied to crops as an insect-control strategy for many years, and this practice has been widely adopted in agriculture and gardening.
Recently, plants have been developed that express a recombinant form of the bacterial protein, which may effectively control some insect predators.
[31] The idea of recombinant DNA was first proposed by Peter Lobban, a graduate student of Prof. Dale Kaiser in the Biochemistry Department at Stanford University Medical School.
[32] The first publications describing the successful production and intracellular replication of recombinant DNA appeared in 1972 and 1973, from Stanford and UCSF.
[33][34][35][36] In 1980 Paul Berg, a professor in the Biochemistry Department at Stanford and an author on one of the first papers[33] was awarded the Nobel Prize in Chemistry for his work on nucleic acids "with particular regard to recombinant DNA".
Werner Arber, Hamilton Smith, and Daniel Nathans shared the 1978 Nobel Prize in Physiology or Medicine for the discovery of restriction endonucleases which enhanced the techniques of rDNA technology.
This moratorium was widely observed until the US National Institutes of Health developed and issued formal guidelines for rDNA work.
However, concerns remain about some organisms that express recombinant DNA, particularly when they leave the laboratory and are introduced into the environment or food chain.
