Biotechnology case studies

Question 1

Norman Borlaug and the ‘Green Revolution’

Answer 1

• American agronomist
• Collaborated with Mexican scientistst to improve wheat, and with scientists from India and Pakistan to adapt new wheats to new lands
• At the time he received the Nobel Prize for this work in 1970, he was researching triticale, an genetically modified grain species derived from a cross between wheat and rye that could be superior to either wheat or rye in nutritional quality and productivity (hybrid vigour)
• Won the Nobel Prize because he was credited with saving over a billion people from starvation

Pros

• Increased the productivity of agriculture worldwide as high-yielding crop varieties were planted

Cons

• Continued planting of only these varities could lead to a reduction in genetic diversity. Prior the revolution, there were about 30,000 rice varities in india. However by 2015, only around 10 of the most productive varieties were being grown in those areas → decreased biodiversity → more vulnerable to sudden environmental changes
• Some farmers were unable to access these high-yielding crop varieties, leading to a widening of the wealth gap in society as farmers who planted high-yielding crops profitted well (can be unethical)

Question 2

Insulin production from bacteria

Answer 2

Overview:

• Insulin is an essential protein that regulate blood sugar levels in humans and animals. it removes glucose from the blood, preventing blood sugar levels from becoming too high
• People with diabetes have a shortage of insulin, as their immune system destroys cells that make insulin in the pancreas. Diabetics thus require external sources of insulin

Why bacteria

• Insulin can be harvested from bacteria for use in humans
• The human insulin gene can be spliced into a bacterial plasmid using DNA recombination technology. The recombinant DNA is then returned to a bacteria, where exponential cell growth causes copious amounts of the insulin gene and insulin to be produced
• The insulin can be harvested from the bacteria for pharmaceutical use in humans

Pros

• Bacteria divide rapidly, allowing for exponential growth. This enables large quantities of insulin to be produced in a short amount of time. This enables insulin pharmaceuticals to be manufacture in large quantities for use by diabetics, improving their health and quality of life
• Overcomes ethical issues for diabetics who refuse to use pig’s insulin due to religious beliefs or vegetarianism
• Absorbed more rapidly than animal-derived insulin, because the insulin is produced using a human gene

Cons

• Some diabetics experience an increase in episodes of hypoglycemic complications after using bacteria-produced insulin
• The production cost of bacteria insulin tends to be high, because bacteria need to be grown in large tanks. Also, bacteria are very small, so a very big amount of bacteria need to be grown to produce enough insulin for commercial use

Question 3

Ice-minus Bacteria

Answer 3

Ice-minus bacteria is used to minimise crop damage due to frost development.

• P. syringae produces an ice-protein that allows for the efficient formation of ice crystals around it when the temperature drops to just below freezing.
• Found on crop leaves (e.g. strawberries) → severe damage in winter seasons.

Ice-minus strain:

Genetically modified so the gene responsible for the synthesis of ice protein is knocked-out through mutagenic processes such as UV radiation.

• Ice-minus strain was introduced and competed with ice-plus (regular bacteria) for the same ecological niche.
• If displacement occurred, the crops do not suffer damage from ice crystals. Even if the ice-minus bacteria don’t succeed, the amount of ice present would be reduced due to competition. This increases crop yield overall.

Question 4

Enviropigs

Answer 4

Enviropigs can digest phytate, the main form of phosphorus in pig feed, which is essential in their diet. This is inserted through a recombinant plasmid containing a promoter gene to regulate expression and the phytase gene from e. coli.

Pro:

• Metabolic characteristic: efficiency of digestion in pigs, reducing the high phosphorous content in pig faeces that is a dangerous environmental pollutant.
• More effective than adding synthetic phytase to feed, which can denature

Con:

• Resistance from consumers to consume genetically modified meat stopped research on Enviropigs and the stock was euthanized.
• Like who wants a fecal bacteria gene in their pork????

Question 5

Antivenom

Answer 5

Some snake bites can be deadly, but can be treated with life-saving antivenom. A horse is given small, non-lethal doses of venom, and the antibodies to the nevom are collected and purified from the horse’s blood.

Pro:

• Some snake bites are deadly if not treated, so this is an essential medicine for snakes, spiders, and scorpions, and it significantly reducing fatalities and long-term health complications

Con:

• Economic accessibility: Antivenom is required in sub-Saharan Africa, India, and South America, but there is limited accessibility - production is costly, and pharmaceutical companies have little financial incentive to produce it.
• Reliant on stable animal populations - could be susceptible to disease etc.
• Animal welfare issues are raised - though the impacts are minimised, repeated injections and blood extraction can cause suffering (unethical!!!)

Conclusion:

Development of synthetic antivenoms and plant-based alternatives could provide more humane, accessible treatments.