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Transgenic cow research at AgResearch Liz Carpenter Dairy Biotechnology.

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Presentation on theme: "Transgenic cow research at AgResearch Liz Carpenter Dairy Biotechnology."— Presentation transcript:

1 Transgenic cow research at AgResearch Liz Carpenter Dairy Biotechnology

2 Contents of the Talk Introduction to AgResearch Terminology Steps to develop a transgenic Biological implications Ethical implications Questions

3 Introduction to AgResearch One of the largest life sciences companies in the Southern hemisphere Employs > 1300 staff Have science capabilities in: Plant genes Animal genes Food and health Agri-technologies Sustainable resource management

4 Transgenic programme Aim:produce high value proteins, for use in human pharmaceuticals, in cow’s milk First transgenic calves born in 2000 Approx. 25 people involved in the generation of successful transgenics Planning and research has taken more then 6 yr

5 Terminology (i) Genome of an organism The set of chromosomes, containing all the genes and associated DNA. DNA (deoxyribonucleic acid) String of nucleotides (bases A, T, G, C) which carries the genetic information of a cell. Carries the necessary information to construct proteins.

6 Terminology (ii) Gene Segment of DNA that codes for a protein Cloning Creates a whole organism from a single cell This organism will have all the same genes as the original cell…including any genetic modifications

7 Terminology (iii) Transgenic animal DNA from one species, or altered DNA from the same species, is introduced into the genome

8 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source Isolate gene sequence Design transgene Transform bovine cells with transgene Select for transgene positive cells Clone with genome from these cells

9 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Increased casein production in milk leads to: - increased calcium in milk - improved processing for cheese Human-derived myelin basic protein (MBP) produced in milk could be used as a therapeutic for people with Multiple Sclerosis (MS)

10 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source - A bovine genome library was screened by PCR for colonies containing the casein DNA sequence - Plasmid DNA was extracted as a source of the casein DNA sequence

11 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source Isolate gene sequence The DNA sequence is cut out of the bacterial plasmid with specific restriction enzymes There are over 100 restriction enzymes, and each cuts DNA at a specific nucleotide sequence

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13 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source Isolate gene sequence Design transgene The gene must be adapted to be expressed in the bovine mammary gland

14 How to make a GMO cow in 7 basic steps The transgene is made up of the desired gene, bracketed by a: a)selectable marker gene, e.g. antibiotic b)promotor sequence c)termination sequence StartStopSelectionDesired gene

15 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source Isolate gene sequence Design transgene Transform bovine cells with transgene

16 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source Isolate gene sequence Design transgene Transform bovine cells with transgene Select for transgene positive cells - Cells are incubated with an antibiotic - Cells which have the transgene integrated into the chromosome will survive

17 Selection Cell carrying transgene + antibiotic for 2 days Check for presence of transgene by PCR & Southern blot

18 PCR (polymerase chain reaction) DNA unzips when heated Single strands of complementary DNA bind together(A – T, G – C, T – A, C – G) DNA polymerase repairs second strand of DNA (assuming free nucleotides present)

19 Principles of PCR

20 Principles of PCR

21 It’s Mum’s 40 th birthday on Saturday and we’re having a surprise party at 8 pm. Can you ring two people for me ?

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23 Cycle:

24 Principles of PCR

25 Southern Blot Transformed cell DNA is extracted DNA fragments are separated by gel electrophoresis DNA is transferred onto a nitrocellulose filter Specific DNA fragments are detected by hybridization to radioactive probes (Non-radioactive techniques are also available)

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27 How to make a GMO cow in 7 basic steps Identify trait (gene) of interest Extract DNA (with gene) from source Isolate gene sequence Design transgene Transform bovine cells with transgene Select for transgene positive cells Clone with genome from these cells

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29 Transgenic Cows 2003

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31 How to show a GMO cow is expressing the gene of interest in milk  -casein A1A1 A2A2 A3A3 Casein plus Transgene  -casein A3 WT  -casein A1A2 Genetic background A1A1 A2A2  -casein A3A3

32 Biological Implications Benefits of GMO animals Casein cows - milk requires less processing »- less environmental pollution - increased natural calcium levels BioPharming: Cows make 20 litres milk/day Enviropigs:Digest phosphorous efficiently Reduce P in manure and runoff Disease resistance eg mastitis (bacteria in milk) Xenotransplantation (using animal tissues for human transplantation)

33 Biological Implications Risks of GMO animals Horizontal Gene Transfer ? –What is the risk ? –Can it happen? »Whole transgene & promotor must be released »DNA is easily broken down (6 hr in soil) »Transgene must be taken up whole »Transgene must be integrated into new organism »Mammalian DNA can’t be “read” by bacteria »Transgene must give new host some benefit for it to be maintained – is this likely ?

34 Biological Implications Risks of GMO animals Mixing with non-GMO animals May get into the human food chain AgR maintains secure Containment Facilities No transgenic animals leave the facility EVER !

35 Containment Facility – main gate

36 Access No Unauthorised Entry Access procedures displayed in entrance No unsupervised access without training Visitors allowed with Operator’s and/or Managers consent Daybook

37 Perimeter double fence

38 Ethical Implications Science deals with testable facts Ethics considers right & wrong: Not testable May change between cultures / religions May change over time (with new discoveries) Do we need to be scientific experts to have an ethical opinion about GE ? (e.g. consider nuclear weapons)

39 Ethical Implications Two main types of ethical issues for GMOs Extrinsic issues, ie consequences of application Potential benefits & harms / risks (Uncertainty – facts vs beliefs) Human & animal welfare Environment – are we changing the world ? Intrinsic issues - issues of rights, responsibilities Include religious, spiritual, cultural beliefs

40 The morality continuum: where do you stand? All genetic engineering is bad Insulin produced by GM bacteria saves lives My mother is a diabetic. She would die if she relied on pig insulin because it makes her sick. I can't afford to buy insulin so now I am blind. Where does it come from? Labelling is too difficult for bulk products The cost of keeping GM products separate outweighs any commercial gain I will have an allergic reaction to food with any traces of peanut. It is a matter of life or death whether food is labelled correctly.

41 The morality continuum: where do you stand? What is the science involved? There is no DNA in the oil from GM conola plants. Therefore the product is GM free. Cows which eat GM plants break down the DNA in the gut. Therefore the cows are GM free. The foreign gene is only expressed in the leaves of canola. This means the seeds are GE free.

42 Questions


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