gmo - genetically modified organisms
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GENETICALLY MODIFIED ORGANISMS-By Aishwarya.R4BCBWhat is the NEED for Genetically Modified Organisms?Man is dependant on animals for milk, meat, eggs, wool, leather etc.Climate change will make it increasingly difficult to feed the world.With the global population expected to reach more than nine billion by 2050, however, the world might soon be hungry for such varieties.Drought, damaging storms, and very hot days are already taking a toll on crop yields.Climate change is likely to make the problem far worse, bringing higher temperatures and, in many regions, wetter conditions that spread infestations of disease and insects into new areas. Drought, damaging storms, and very hot days are already taking a toll on crop yields, and the frequency of these events is expected to increase sharply as the climate warms. For farmers, the effects of climate change can be simply put: the weather has become far more unpredictable, and extreme weather has become far more common.
TRANSGENESISTransgenesis refers to the phenomenon of introduction of exogenous DNA into the genome to create and maintain a stable heritable character.
The foreign DNA is called the TRANSGENE.
The animal whose genome is altered is called TRANSGENIC.
IMPORTANCE OF TRANSGENIC ANIMALS OR GENETICALLY MODIFIED ANIMALS:Improvement of Genetic characters.Models for understanding human diseases.Medical and pharmaceutical applications.Important fro improving the quality and quantity of milk, meat, eggs, and wool production.In understanding Molecular biology, genetics, immunology and cancer,
First transgenic animal was a mouse.
CHARACTERSMOUSERATSizeSparrow sizedNearly 1 poundBest known speciesCommon House Mouse (Mus Musculus)Black Rat (Rattus Rattus); Brown Rat (Rattus Norvegicus)Genetic DifferencesMice have 20 chromosome pairs & 2.6 million base pairsRats have 21 chromosome pairs & 2.75 million base pairsEarsEars are large relative to the head.Ears are small relative to the headtailA mouse is small and has a skinny tail.A rat is bigger and has a thicker tail.Why Mouse???METHODS OF INTRODUCING A FOREIGN GENERetroviral Vector MethodMicroinjection MethodEmbryonic Stem Cell Method Retroviral Vector Methodretrovirus is any virus belonging to the viral familyRetroviridae. All The genetic material in retrovirusesis in the form ofRNAmolecules, while the genetic material of their hosts is in the form ofDNA. When a retrovirus infects a host cell, it will introduce its RNA together with someenzymesinto the cell. This RNA molecule from the retrovirus must produce a DNA copy from its RNA molecule before it can be considered part of the genetic material of the host cell. Retrovirus genomes commonly contain these three open reading frames that encode for proteins that can be found in the mature virus. Group-specific antigen (gag) codes for core and structural proteins of the virus, polymerase (pol) codes for reverse transcriptase, protease and integrase, and envelope (env) codes for the retroviral coat proteins. Retroviral vectors are created by removal op the retroviral gag, pol, and env genes. These are replaced by the therapeutic gene. In order to produce vector particles a packaging cell is essential. Packaging cell lines provide all the viral proteins required for capsid production and the virion maturation of the vector. These packaging cell lines have been made so that they contain the gag, pol and env genes. Early packaging cell lines contained replication competent retroviral genomes and a single recombination event between this genome and the retroviral DNA vector could result in the production of a wild type virus. Following insertion of the desired gene into in the retroviral DNA vector, and maintainance of the proper packaging cell line, it is now a simple matter to prepare retroviral vectors. One of the problems ofgene therapyusing retroviruses is that the integrase enzyme can insert the genetic material of the virus in any arbitrary position in the genome of the host. If genetic material happens to be inserted in the middle of one of the original genes of the host cell, this gene will be disrupted (insertionalmutagenesis). If the gene happens to be one regulating cell division, uncontrolled cell division (i.e., cancer) can occur. This problem has recently begun to be addressed by utilizing zinc finger nucleases or by including certain sequences such as the beta-globin locus control region to direct the site of integration to specific chromosomal sites.
Retro viral vector methodMicroinjection Method
Apronucleus is the nucleus of aspermor anegg cellduring the process offertilization, after the sperm enters the ovum, but before they fuse. Sperm and egg cells arehaploid, meaning they carry half the number ofchromosomes. The male and female pronuclei don't fuse, although their genetic material do. Instead, their membranes dissolve, leaving no barriers between the male and female chromosomes. Their chromosomes can then combine and become part of a single diploid nucleus in the resultingembryo, containing a full set of chromosomes.EMBRYONIC STEM CELL METHOD
TRANSGENIC PLANTSNEED FOR TRANSGENIC PLANTSTo improve crops with the desired traits.Resistance to diseases caused by insects, viruses and fungi and bacteria.Resistance to herbicides, temperature, drought, salinity, ozone, intense light.Imrovement of crop yield, quality, storage, longer shelf life of fruits and vegetables.Transgenic plants as bioreactors for manufacture of commercial products like proteins, vaccines and biodegradable plastic.The major objective of plant biotechnology is to develop plants that are resistant to biotic and abiotic stresses. Biotic Stress can be described in 3 major categories:
INSECT RESITANCEVIRUS RESISTANCEFUNGAL AND BACTERIAL RESISTANCERESISTANCE TO BIOTIC STRESS:Common Name of PestScientific NameCrops damagedCotton bollwormHelicoverpa zea CottonCotton leafwormSpodoptera littiralis Rice, cotton, maizeTobacco BudwormHeliothis virescens Tobacco, cottonTomato Fruit wormHeliothis armigera Tomato, cottonBrown plant hopperNilapavarta lugens RiceINSECT RESISTANCE
The damage to crops are mainly caused by insect larvae and pests.E.g.: Bollworms, Beetles, Grasshoppers, Aphids
95% of pesticide sprayed is washed away.Chemical pesticides cause pollution as they are not degradable.Toxic to plants, human and animals.
RESISTANCE GENES FROM MICROORGANISMSBacillus thuringiensis (Bt) toxin:Discovered by Ishiwaki 1901Gram negative, soil bacteriumProduces parasporal crystalline protein with insecticidal toxin i.e, ICP- Insecticidal Crystalline Protein.These proteins are also called Cry proteins.
MODE OF ACTION OF CRY PROTEINS:ADVANTAGES OF TRANSGENIC PLANTS WITH Bt Genes:
Bt genes could be expressed in all parts of the plant including roots, stem and fruits.Bt toxin rapidly degrade in environment.Toxin produced kills only target insect. Safe for human consumption.Reason: Conversion of prototoxin to toxin requires alkaline Ph and specific proteases and these are absent in humans and animals.
Golden RiceGolden rice is a variety of Oryza sativa rice produced from genetic engineeringMain purpose is to provide pro-vitamin A to third world, developing, countries where malnutrition and vitamin A deficiency are common.
Who Began the Golden Rice Project?Started in 1982 by Ingo Potrykus-Professor emeritus of the Institute for Plant SciencesPeter Beyer-Professor of Centre for Applied Biosciences, Uni. Of Freiburg, Germany
Funded by the Rockefeller Foundation, the Swiss Federal Institute of Technology, and Syngenta, a crop protection company.
Effects of MalnutritionSymptoms of vitamin A deficiency (VAD) include; night blindness, increased susceptibility to infection and cancer, anemia (lack of red blood cells or hemoglobin), deterioration of the eye tissue, and cardiovascular diseaseNearly 9 million children die from malnutrition each year. A large proportion of those children die from common illnesses that could have been avoided through adequate nutritionThe reduced immune competence increases the morbidity and mortality rates of children34GoalsMutate rice plants to produce carotenoids, or organic pigments, specifically -carotene (pro-vitamin A) in the endosperm, the edible part of the grain
Make Golden Rice accessible locally, free of charge to farmers, who are able to grow, save, consume, replant and locally sell Golden Rice
Vitamin A(Retinol)35How Does It Work?The addition of 2 genes in the rice genome will complete the biosynthetic pathway1. Phytoene synthase (psy) derived from daffodils (Narcissus pseudonarcissus)(Phytoene synthase is a transferase enzyme involved in the biosynthesis of carotenoids. It catalyzes the conversion of geranylgerany pyrophosphate to phytoene.)2. Lycopene cyclase (crt1) from soil bacteria Erwinia uredovoraProduces enzymes and catalysts for the biosynthesis of carotenoids (-carotene) in the endosperm
36The psy and crt1 genes were transformed into the rice nuclear genome and placed under the control of an endosperm-specific promoter, so they are only expressed in the endosperm. The exogenous lyc gene has a transit peptide sequence attached so it is targeted to the plastid, where geranylgerany diphosphate formation occurs. The bacterial crt1 gene was an important inclusion to complete the pathway, since it can catalyze multiple steps in the synthesis of carotenoid, while these steps require more than one enzyme in plants.
The end product of the engineered pathway is lycopene, but if the plant accumulated lycopene, the rice would be red. Recent analysis has shown the plant's endogenous enzymes process the lycopene to