Lecture 14 - genetic manipulation of animals Flashcards Preview

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Flashcards in Lecture 14 - genetic manipulation of animals Deck (25):

3 reasons why trasngenic animals are effective bioreactors for pharmeceutical proteins

many proteins require complex modifications only possible in eukaryotes
proteins can be produced in large amounts - >2g per litre
increased safety compared with extraction from human tissues


What is a good place to express proteins in mammals and why

ease of production (already make lots)
mammary gland specific promoters available so protein not expressed in entire animal
high level production possible


Name some other sources of protein expression in animals

blood, urine, saliva, semen, eggs


List the disadvantages of useing milk as location to express desired proteins

purification can be hard:
-Milk is biocolloid ie. a suspension of micelles which are made up of casein and calcium (precipitate to remove casein)
-Fat must centrifuged out
The gene has the potential to negatively affect milk supply
Covelant modifications may not be conserved between different tissue types


What would be an alternative to human alpha 1-antitrypsin being extracted fromnn blood plasma, why would we look for an alternative and what is it for

Express in sheep's milk instead
costs $40,000 a year and 60mg/kg required once a week per patient


How was AAT expressed successfully in good old tracy the sheep

Ovine beta lactoglobulin gene promotor fused to human AAT gene.
Sheep created by pronucelar injection
40g/l conc in milk was the result


What is Antithrombin III (AT III)

plasma protein with anticoagullant and anti inflammatory properties.
A glycoprotein usually synthesised in the liver
The first transgenically produced protein to be approved for human therapeutic use


What is ATT used for and what is the world wide requirement

Used for patients with antithrombin deficiency undergoing high risk surgical procedures


Compare mammalian cell culture as a way of expressing AAT with transgentic goat

MCC can produce 100mg/l
has 50% recovery
would need 2,000,000l of mammalian culture to fulfil world wide need
Transgenic goat producing AAT in milk produced by pronuclear injection, pro nuclear transfer from transgenic fetal fibroblasts expressing AAT
2g/l goats milk achieved , only need 150 goats


What is xenotransplantation

the transplantation of living cells, tissues, and or organs between one species and another


Potential benefits of xenotransplanation

animals could potentially provide an unlimited supply of cells tissues and organs for transplanting into humans
Human organs are in short supply


Why are pigs favoured as organ donors over e.g. baboons

fewer viruses
,more offspring
fewer moral objections
pig heart valves already a success


What are the essential prerequisites for successful xenotransplantation

immunological barriers overcome
transmission of pathogens prevented
anatomy and physiology compatible


What is the main immunological issue facing xenotransplantation

Hyper Acute Rejection
immediate and catastrophic because the recipient already has antibodies against donor tissue, specifically against the small carbohydrate Gal alpha (1,3)-gal


What is a potential solution to HAR

create transgenic pigs with the carbohydrate knocked out


What are the agricultural uses of GM animals

Disease resistance - introduce genes that confer animal Resistance to parasites and pathogen
Carcass composition - make leaner meat
Lactation - modify milk components or make hypoallergenic
Wool production - incr yield
Environmentally friendly farm animals - address intense farming issues


What is the official name of mad cow disease

Bovine Spongiform Encephalopathy


What is BSE caused by

propogation of misfolded forms of normal cellular prion protein PrPc


How have cows been genetically modified to get resistance to mad cow disease

knocked out PRPN gene in fibroblasts, produced clones from these cells


How is carcass composition in pigs altered, and how genetically?

more unsaturated linoleic acid in meat
FAD2 demnaturase from spinach introduced via the microinjection of pronuclear embryos


Is the introduction of FAD2 to pigs efficient? If not state why

11 out of 16 recipient pigs (of injected embryos) became pregnant, 70 piglets
Of these only 15% injected embryos developed to full term
Only 6 of the piglets were transgenic-2 still born, 1 died day after birth, 2 males 1 female survived
FAD2 mRNA detected in 1 male and 1 female founder pig
male mated with 2 WT females, 32 piglets produced, 21 alive. 8 carried transgene
female mated with WT male, 12 piglets, 3 live.


How might one want to alter milk composition and why. O,h and how

Increase levels of human lysozyme
It is a:
Non specific immune factor
anti inflammitory ]
protects against gram positve bacteria
will confer disease resistance to infants if consumed
How: expressed in transgenic cloned cattle

Remove B-lactoglobulin because it's a major milk allergen
How: use RNA interference to target BLG gene
Introduce RNAi construct in calf fibroblast perform somatic cell nuclear transfer (like dolly the sheep)


What do enviropigs genetically contain and how was it introduced

a transgene construct containing the murine (mouse) parotid secretory protein promoter gene sequnce and the Ecoli phytase gene.
Introduced via pro nuclear microinjection of fertilized embryos


What is the problem with pigs

Can't digest phylate, so lots in their manure
leads to eutrophication


What changes have been made to pigs to make them greener

phytase enzyme in salivary gland so less phosphorous products in manure