Friday, 23 March 2012

Pain Free Animals


Genetically Engineered Pain Free Animals


When you get that juicy looking piece of steak placed in front of you for dinner, do you stop and wonder where it came from? Did you know that humans consume over 300 tonnes of meat annually (Ewen Callaway 2009). That’s a lot of meat, but where does it come from? Most people won’t care, as long as it’s on a plate at the end of the day, but just for the benefit of those who do, I’ll tell you. The meat comes from animals squished together in horrid farm factories where they are treated with all the cruelty humans can muster. Animal rights activists may demand better treatment (Lisa Zyga 2009), but as long as people refuse to become vegetarians, there is little hope, and that little hope is this recent article; ‘Would Pain-Free Animals Make a More Humane Hamburger’ by Lisa Zyga that states that through recent advances in genetic engineering, there may be a way (Lisa Zyga 2009).

The article mentions two studies that have made progress in the manipulation of pain. One, where mice have been found to lack the Nav1.7 gene, resulting in reduced pain recognition, and another where specific enzymes and genes are removed (Lisa Zyga 2009). There is also a third alternative, and that is growing animal muscle cells that could be used in processed meats, which I am sure would taste amazing…But I’m going to focus on the second study mentioned, it seems to be the most advanced out of the three.
So, LTP stands for Long Term Potentiation. Its where, through repetition, signal transmission between two neurons are strengthened. This under lays memory and learning. LTP occurs in the cingulate cortex of the brain, which plays a key role in awareness and memory.


 For LTP to occur, an outside signal is sent to a G protein, in this case mG1uR1. This then signals the adenylyls cyclases (AC1 and AC8), which are enzymes, which respond with Ca2+ and converts ATP into cAMP, which is a secondary messenger that interacts with protein Kinase (Adam Shiver 2009).
If the enzymes, AC1 and AC8, are knocked out, then LPT cannot occur. Knockout mice have been genetically engineered to not contain the AC1 and AC8 gene. This is done by inserting artificial DNA into the nuclei of a cell, which is then implanted into the uterus of a mouse. The offspring are then interbred so that both copies of the gene are altered (Paul Arnold 2009).

 
Foreign gene is injected into the cellular
structure containing the genetic material 
from the father.

Embryo is transferred into a foster 
mother for embryonic development.

Mouse pups (i.e., F1 animals) carrying and
 expressing the foreign gene are identified.

F1 animals carrying the foreign gene are 
mated with each other.

Each offspring (i.e., F2 animal) carries the
 foreign gene in all of its cells.
(Barbara Bowers 2000)




 These knockout mice still showed signs of acute pain when subjected to testing, e.g. withdrawing their paws when placed onto a hot plate. However, when a volatile substance was injected into their paws, the knockout mice showed highly reduced licking compared to the normal mice (Adam Shiver 2009). This showed that by knocking out the enzymes AC1 and AC8, persistent pain was highly reduced because LTP cannot occur, causing the mouse to still feel the pain but not find the sensation unpleasant (Adam Shiver 2009).
So we can see that scientists were able to create and breed mice that lacked the AC1 and AC8 enzymes. Meaning LTP could not occur in the cingulate cortex of the brain, leading to the reduction of persistent pain. The pain was not completely eliminated, because acute pain was still experienced. But this is a big step towards helping out those poor animals.

Yasmin Johnston 42626455

References

Adam Shiver, 2009, Knocking Out Pain in Livestock: Can Technology Succeed Where Morality has Stalled?, published online, viewed 16th march 2012,

Barbara Bowers, 2000, applications of transgenic and knockout mouse in alcohol Research, viewed 16th march 2012,

Ewen Callaway, 2009, Pain-Free Animal Would not be Guilt Free, New Scientist, viewed 16th march 2012,
< http://www.newscientist.com/article/mg20327243.400>

Lisa Zyga, 2009, Would Pain-Free Animals Make a More Humane Hamburger?, New Scientist, viewed 16th march 2012,
< http://www.physorg.com/news171216895.html>

Paul Arnold, 2009, How Are Knockout Mice Created?, published online, viewed 16th march 2012,
< http://www.brighthub.com/science/genetics/articles/46372.aspx>

Wikipedia, 2012, adenylate cyclase, published online, viewed 16th march 2012,
< http://en.wikipedia.org/wiki/Adenylate_cyclase>



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