Application of genetic engineering

By,Pillai Aswathy viswanathPG 1 BotanySt. Thomas college kozhencherry

•Genetic engineering, also called genetic modification

• to add one or more new traits that are not already found in that organism.

•In France , this technology is called biomolecular engineering

•In 1973,Stanley Cohen and Herbert Boyer designed a methodology for transferring certain genes from one organism to another

• The gene is a small piece of DNA that encoded for a specific protein

• A desired gene is inserted in to a vector DNA so that a new combination of vector DNA is formed

• The DNA formed by joining DNA segments of two different organisms is called recombinant DNA or chimeric DNA

• The gene is introduced in to a cell in the form of recombinant DNA

• The gene manipulation therefore is known as recombinant DNA technology

• The organism whose genetic make up is manipulated using recombinant DNA technique , is called  genetically modified organism (GMO). 

• GMOs produced through genetic technologies have become a part of everyday life,

• However, while GMOs have benefited human society in many ways

• Genetic engineering techniques have been applied in numerous fields including :-

Agriculture Medicine Genetic studies . etc• some disadvantages also exist;

therefore, the production of GMOs remains a highly controversial topic in many parts of the world.

Application in Agriculture

• Improvement in agricultural production and the food and nutrition situation depents on land ,water and energy resources.

• From 1970 a new type of reasearch started with the aim of producing new varieties of plants by genetic recombination techniques.

• They are genitically engineered plants • They have acquired a new trait from the

introduced DNA and inherit the trait for many generations

• The new plants produced by such techniques are supposed to be:-

virus resistant plant insect resistant plants, herbicide resistant plant • growing crops of your choice (GM food)• for preservation of fruits• Some genetically engineered microorganisms

are used as nitrogen fixers

virus resistant plant• to make virus resistant

crops. The most common way of doing this is by giving a plant a viral gene encoding the virus' 'coat protein'.

• The plant can then produce this viral protein before the virus infects the plant.

• When the virus tries to infect the plant, the production of its essential coat protein is already blocked.

• Tansgenic tobacco is developed by introducing gene coding for capsid protien of tobacco mosaic virus

• TMV-coat protein inserted in to tobacco cell using Ti plasmid

• Viral capsid inhibit viral replication of TMV when infected

• All genetically modified virus resistant plants on the market (e.g. papayas and squash) have coat protein mediated resistance.

GM squash with virus resistance (top) protects the squash from the damaging effects of the virus (bottom)

papaya with virus resistance

insect resistant plants,• Insect attack is a serious agricultural

problem leading to yield losses and reduced product quality.

• Each year, insects destroy about 25 percent of food crops worldwide.

• many transgenic plant with insect resistantance have been developed by adopting gene transfer methods

• The gene helps the plants produce proteins that are toxic to certain insects

• They reduced the use of chemical pesticides in agriculture

• The genetically modified crops is called Bt-crops, because the insect-killing gene in the plant comes from the bacteria Bacillus thuringiensis.

• Bt gene produces insecticidal crystal protien (ICP) also known as cry protien which is in an inactive, crystalline form.

• When consumed by insects, the protein is converted to its active, toxic form (delta endotoxin), which in turn destroys the gut of the insect and is completely safe for humans.

Examples of some Bt crops A common soil bacterium so called because it was first isolated in the Thuringia region of Germanydiscoverd by Ishiwatari in 1901

herbicide resistant plant • Many transgenic plants with herbicide

resistance have been developed by using genetic engineering

• Such transgenic plants tolerate the herbicides and be safe in the field ,when the herbicides are applied in the field

Example for herbicide resistant plant

Growing crops of your choice •  Genetically modified foods are foods

derived from genetically modified organisms. 

• The FLAVR SAVR tomato was the first genetically engineered crop product 

• Through genetic engineering, the ripening process of the tomato will slow down and thus prevent it from softening, while still allowing the tomato to retain its natural colour and flavour.

• Thus the shelf life of the tomato become improved

•  The tomato was made more resistant to rotting by adding an  gene which interferes with the production of the enzyme polygalacturonase.

• The enzyme normally degrades pectin in the cell walls and results in the softening of fruit which makes them more susceptible to being damaged by fungal infections. 

• Improved taste and look

BiofertilizersGenetically engineered nitrogen fixers• Nitrogen is the most essential macro-element

for proper healthy crop• Molecular nitrogen in the atm. Is converted to

biologically usable forms by nitrogen fixing micro organisms eg:Rhizobium

• In leguminous plants nitrogen fixing nodules are formed in the roots due to the symbiotic realation ship with bacteria

• The special ability of nitrogen fixing bacteria is due to the presence of an enzyme called nitrogenase complex

• Some genetically engineered micro organism are used as nitrogen fixers

• rizobium species carry nif genes , later genes will transferred to the free living bacteris like klebsiella pneumoniae ,salmonella typhimurium etc

• These genetically engineered microbes are capable of fixing the atmospheric nitrogen in the soil they are used as biofertilizers in agriculture.

• In 1971 dixon and postgate successfully transferred the nif genes to free living nitrogen fixer klebsiella pneumoniae

•  Klebsiella is naturally found as a free-living soil bacterium 

Application in Medicine.• Some of the most promising and powerful

applications of genetic engineering are in the field of medicine.

• Researchers are using it to diagnose and predict disease, and to develop therapies and drugs to treat devastating diseases like cancer, Alzheimer's, diabetes, and cystic fibrosis. Etc.

• At present about 30 recombinant therapeuties have been approved for human use

• The application of recombinant DNA technology has played a major role in :-

Production of human insulin Production of human growth hormone Production of vaccines production of interferons Gene therapy

Production of human insulin• Insulin is a hormons produced by  beta

cells in the pancreas that controls the absorption of glucose by cells.

• The deficiency of insulin leads to diabetics in man

• Diabetics is treated by injecting insulin• In the past, diabetics needed to take

insulin purified from pigs and cows to fulfill their insulin requirement. However, non-human insulin causes allergic reactions in many diabetics.

• Recombinant DNA technology has allowed the scientists to develop human insulin by using the bacteria as a host cell

• it is also available in the market. It is believed that the drugs produced through microbes are safer.

Production of human growth hormone

• Human growth hormone (HGC) is secreted by the anterior lobe of pituitary gland . It also called somatotropin

• The deficiency of somatotropin leads to dwarfism in man

• The cDNA of somatotropin was introduced in to Ecoli The genetically engineered E coli produces human growth hormone

Production of vaccines • A vaccine is a biological preparation that

improves immunity to a particular disease• Genetic engineering is used to developed

vaccines against some sever diseases• Hepatitis B vaccines, First human trials of

vaccine against Hepatitis B• A gene coding for surface antigen HBsAg was

isolated from Hepatitis B virus and cloned in Ecoli

• The genetically engineered microbes will produced HBs antigen

• This antigen is isolated purified and used for vaccination

• Edible Vaccine involves introduction of selected desired genes into plant and then inducing these altered plants to manufacture the altered protein.

• Banana is currently being considered as the edible vaccine against hepatitis B

Production of interferons

• Interferons is an antiviral protein.• Interferons is produced by infected

animal cells and it protects the cells from the second viral infection

• They induced the production of cellular protein kinase and phosphodiesterase which selectively destroy viral RNAs and proteins. So the virus fail to multiply in the cell

• The cDNA of the various interferons were isolated from human cell and introduced in to E coli

• The genetically engineered E coli cultures produced interfrons

Gene therapy• Medical scientists now know of about 3,000

disorders that arise because of errors in an individual's DNA.

• Conditions such as sickle-cell anemia, Huntington's chorea, cystic fibrosis, and Lesch-Nyhan syndrome are the result of the loss, mistaken insertion, or change of a single nitrogen base in a DNA molecule.

• Genetic engineering makes it possible for scientists to provide individuals who lack a certain gene with correct copies of that gene.

• Treatment of genetic disorders by replacing defective gene by a normal functional gene is called gene therapy

• The gene used in gene therapy is often called gene drugs

• The drug gene may be introduced in to somatic cells or germs cells or zygotes .

• If the genes are introduced into somatic cell it is called somatic cell gene therapy

• If genes are introduced into eggs or zygotes it is called germline gene therapy

• The gene drug may be introduced in to target cells by using retrovirus, electroporation ,transfection etc

• The first clinical gene thearapy was given in 1990 to a 4 year old girl with adenosine deaminase deficiency

Application in Genetic studies• Today recombinant DNA

technology is used extensively in research laboratories worldwide to explore myriad questions about gene structure, function, expression pattern, regulation, and much more.

• 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.[8

• Recombinant DNA is used to identify, mapping genes sequence, and to determine their function.

• Mapping helps in finding the inheritance of many rare genetic disorders such as cystic fibrosis, haemophilia etc.

• It helps in understanding the expression and regulation of a commercially important trait.

] • rDNA probes are employed in

analyzing gene expression within individual cells, and throughout the tissues of whole organisms.

• Recombinant proteins are widely used as reagents in laboratory experiments and to generate antibody probes for examining protein synthesis within cells and organisms.

Reference• Rev.Fr.Dr.S. Ignacimuthu(1998) basic

biotechnology .Tata McGraw-Hill publishing company

• Bilgrami K.S,Pandey A.K (2001)introduction to biotechnology.CBS Publishers

• Gupta P K (2007)elements of biotechnolgy. Rastogi publication

• geneticsresearch.org/applications-of-genetic-engineering.php

• www.boundless.com • www.infoplease.com/cig/biology/dna-technology-

applications.html