Safe Guards of Genetic Engineering

Safe Guards of Genetic Engineering

	Safe Guards of Genetic Engineering A committee chaired by Paul Berg held a series of discussions in I 1973 and 1974 and published a letter outlining the potential risks of genetic engineering research. In 1975 an international meeting held at the Asilomar Conference Center, California, formulated provisional guidelines for recombinant DNA research. The National Institutes of Health (USA) promulgated certain guidelines in 1976 for U. S. investigators. Foul levels of laboratories (P1 to P4.) with increasing degrees of precautions to be observed were recommended. Thus experiments involvil1g DNA from primate tissue and animal viruses containing harmful genes could only be carried out in the ultra-secure P4 laboratories.
The general safeguards for recombinant DNA research are outlined below. 1. Genes coding for the synthesis of toxins or antibiotics should not be introduced into bacteria without proper precautions 2. Genes of animals, animal viruses or tumour viruses should also not be introduced into bacteria without proper precautions.
3. Laboratory facilities should be equipped to reduce the' possibility' of escape of pathogenic microorganism by using microbial safety cabinets, hoods, negative pressure laboratories, special traps on drains lines and vacuum lines. 4. Use of microorganisms occupying special ecological niches such as hot springs and salt water should be encourage If such organisms escape they will not be able to survive. 5. Use of nonconjugative plasmids as plasmid cloning vectors is recommended as such plasmids are unable, to, promote their own transfer by conjugation.
6.The plasmid cloning vector should be genetically manipulated so that its replication depends upon the host strain, and transmission to other microbes is lethal. 7.Use of microbial host strains that can survive only under laboratory conditions that are not likely to be found in nature(safe laboratory strains) is desirable. Efforts have also been made to create 'crippled' microorganisms for recombinant DNA research. These are so, disabled that they die if they escape from laboratories. In E. coli, diaminopimelic acid (DAP) is an important constituent of the cell membrane. DAP-deficient mutants were created which cannot survive unless provided with DAP by experimenters.
	They are so disabled that they cannot live outside the laboratory, and are thus incapable of causing infection.It was, however, found that some DAP-deficient bacteria mutated back to produce DAP and were thus potentially dangerous. Another gene involved in DAP, production was deleted, so that the bacterium again became DAP deficient. Some DAP-deficients, however, survived by producing a sticky substance called colanic acid Again by genetic manipulation the colanic acid gene was removed, thus producing a safe bacterium. To eliminate the possibility of a weakened bacterium being revived by conjugation, a mutant which cannot produce thymine was created

This cannot survive unless supplied with thymine in the laboratory. Work is in progress to produce still safer strains. The E. coli strain x1776 has been certified by the NIH for genetic engineering work.

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