GMO

Question 1

What is a GMO

Answer 1

An organism in which the genetic material has been altered in a way that does not occur naturally by mating and/or natural recombiantion

Question 2

Whats the difference between consists of GM and produced from - examples

Answer 2

Flavr Savr tomato - consists of GMO - but GM rape seed - produces oil that does not contain living GMOs

Question 3

What are the benefits of GMO

Answer 3

• Can enhance yield without using more land
• improve nutrition especially for malnourished
• reduce dependence on pesticides/chemicals/ enhance taste and quality

Question 4

Problems with GMO

Answer 4

Insect resistant crops/killing of non-target species /undesired cross pollination/super-weeds/toxicity to humans/unknown health outcomes/allergenicity

Question 5

Salmon GMO example

Answer 5

AquAdvantage salmon grow 2 x the rate of wild salmon

Question 6

Cow GMO example

Answer 6

milk with 2 x kappa casein and 20% more beta casein

Question 7

GMO food exzymes example - cheese

Answer 7

Instead of using chymosin from calf’s fore stomach to clot cheese - it can be produced in E.coli - more ethical? / improved productivity

Question 8

In food it can be both agronomical traits and quality traits - explain

Answer 8

agronomical = growth and yield and quality= nutrition and function

Question 9

golden rice

Answer 9

daffdil genes added which produce beta-carotene, a precursor to vitamin A - helps to prevent blindness in developing countries

Question 10

Protato

Answer 10

the AmA1 gene from amaranth plants was used which increased protein content by a third - more lysine and methionine

Question 11

Anti-bruise potato

Answer 11

knocked out phenol oxidase = no enzymatic browning

Question 12

GMOs can have secondary effects eg

Answer 12

they can affect the ability to utilise proline and polyphenols

Question 13

Allergenicity problems eg

Answer 13

soya beans with Brazil nut 2 S albumin can casue nut allergy

Question 14

Name the 3 types of ELISA for determining GMOs

Answer 14

Indirect, Sandwich, Lateral flow

Question 15

Describe Indirect ELISA

Answer 15

1) Antigen coated well - wash
2) specific antibody binds to the antigen - wash
3) enzyme linked antibody bind to specific antibody - wash -
4) substrate is added and converted by enzyme into coloured product - the rate of colour formation is proportional to the amount of specific antibody

Question 16

Describe Sandwich ELISA

Answer 16

1) Monoclonal antibody-coated well - wash
2) antigen binds to antobody - wash
3) a second monoclonal antibody, linked to enzyme, binds to immobilized antigen -wash
4) substrate is added and converted by enzyme into coloured product - the rate of colour formation is proportional to the amount of antigen

Question 17

Describe lateral flow ELISA

Answer 17

They are portable - there is a control band and a test band - both need to be positive to determine that GMO is present - monoclonal antibodies (highly specific) and polyclonal (more sensitive) antibodies can be used

Question 18

Benefits and negatives of lateral flow

Answer 18

simple, fast, cheap (once developed) less prone to false positives however protein denaturation /inactivated target/high upfront cost - less sensitive than PCR

Question 19

Describe PCR

Answer 19

Polymerase chain reaction - amplifies target DNA for the detection of GMOs - two short chemically synthesised DNA fragments called primers are hybridised to the DNA that is then amplified trhough a repeated cycle - each sample doubles the number of DNA molecules

Question 20

Benefits and negatives of PCR

Answer 20

high sensitivity and specificity/reliable but expensive - even though the primer synthesis is inexpensive - as it is so sensitive false positive may occur due to contamination - not portable and requires trained personnel

Question 21

DNA challenge

Answer 21

(Holst-Jensen et al, 2003) explained that a major challenge regarding PCR is the accessibility of GM-derived material

Question 22

multiplex

Answer 22

James et al, 2003 - developed multiplex procedures to simultaneously detect target sequences in GM soybean, maize and canola - in summary = simple, accurate and sensitive - only one reaction is necessary to detect multiple GM target sequences

Question 23

Microarrays - describe

Answer 23

small glass slides with target genes up to 10000 targets

Question 24

Describe procedure for microarrays

Answer 24

1) Isolate DNA from food
2) Label with probe (fluorescent)
3) Wash over microarray
4) Analyse fluorescence
Has the potential to detect all GMOs simultaneously however it is expensive to develop and run - needs trained personnel and uses expensive equipment that is not portable

Question 25

MACRO

Answer 25

(Ning et al, 2014) have developed MACRO - Multiplex amplification on a chip with readout on an oligo microarray - it is a combined microchip PCR and microarray system for high-throughput monitoring of genetically modified organisms = convenient GMO monitoring - covers 97.1% of all GM events that have been commercialied up to 2012

Question 26

Protein - ELISA
Ease of use
Special equipment?
Sensitivity
Duration
Cost/Sample (US$)
Gives quantitative results
Suitable for field test?

Answer 26

Moderate
Yes
High
30-90 minutes
5
Yes
Yes

Question 27

Protein - Lateral flow
Ease of use
Special equipment?
Sensitivity
Duration
Cost/Sample (US$)
Gives quantitative results
Suitable for field test?

Answer 27

Simple
No
High
10 minutes
2
No
Yes

Question 28

DNA - qualitative PCR
Ease of use
Special equipment?
Sensitivity
Duration
Cost/Sample (US$)
Gives quantitative results
Suitable for field test?

Answer 28

Difficult
Yes
Very High
1.5 d
250
No
No

Question 29

DNA - Real-time PCR
Ease of use
Special equipment?
Sensitivity
Duration
Cost/Sample (US$)
Gives quantitative results
Suitable for field test?

Answer 29

Difficult
Yes
High
1 d
450
Yes
No

Question 30

General problems with detecting GMO

Answer 30

• No standard analytical method
• no single tests detect all types of GMOs (microarrays)
• detection methods for procesed foods are less sensitive and reliable than those for raw foods
• for highly refined foods it is impossible to detect the presence of any GM materials e.g. sugar from GM sugar beet
• False positives can occur

Question 31

Comparison of Lateral flow with PCR

Answer 31

(Mazzara et al, 2012) - lateral flow = easy and fast, no specialised staff and no costly set up - however PCR good for when sample could be contaminated by more than one GMO however can only run 10 samples a day

Question 32

Combo lateral flow strips

Answer 32

bring developed to detect multiple GMOs

Question 33

Unauthorised GM material cannot be present at any level

Answer 33

<0.5%

Question 34

What is the threshold for adventitious or accidental presence of GM material in non-GM food or feed sources

Answer 34

<0.9% - does not have to be labelled if the GMOs have EU authorisation

Question 35

What products do not need to be labelled

Answer 35

Cheese made from GMO chymosin (protein chymosin is isolated from calf cell, a copy of the DNA is spliced into a plasmid and inserted into yeast cell for example - cultivate the yeast cell which produces chymosin) or meat, milk, eggs feed on GM animal feed

Question 36

Any intentional use of GM must be labelled eg

Answer 36

Flour, oil, sugar - even if it does not contain GMO just produced by

Question 37

GMOs can only be released into the environment and sold if

Answer 37

a science-based risk assessment shows that safety will not be compromised

Question 38

UK and US

Answer 38

No GM - 70-80% GM

Question 39

GMO legislation

Answer 39

The GM Food and Feed regulation (EC) No. 1829/2003 covers all GM food, animal feed, regardless of any GM material in the final product from april 2004 - The words ‘genetically modified’ or ‘produced from genetically modified (name of the organism)’ must be clearly visible on the labelling of these products.