Transcript Melanin ppt - BLI-Research-in-Synthetic-Biology

PROTECTION FROM UV RAYS
By Tejas Kelkar
There are 3 major types of UV light, UVA, and UVB, and UVC
• UVA is detectable by cells and is just above the visible
spectrum.
• UVB has a shorter wavelength, is can damage cells, and is
really hard to detect.
• UVC is rarer, has a much shorter wavelength, and is
germicidal. Which means it is really dangerous.
Name+ Abbreviation
Wavelength
Ultraviolet A / UVA
400-315 nm
Ultraviolet B / UVB
315-280 nm
Ultraviolet C / UVC
280-100 nm
When there is no UV rays, people with
lighter skin have at most a miniscule
amount of melanin. Photosensors on cells
in the lower epidermis sense UVA and tell
melanosomes to produce melanin. They
produce melanin, which surrounds the
nucleus and protects it from radiation.
While the melanin accumulates,
there is always a chance that
DNA gets mutated
But there is one issue to this
system: the photosensors cannot
detect the more harmful UVB and
UVC as well. Because of this, if
there is a lot of UVB and UVC light
present but not a lot of UVA,
melanin may not build up, causing
major health issues.
People with darker skin have a large
amount of melanin production anyway.
Because of that, even if there is UVB and
UVC radiation, the cell won't be as affected.
If it sees UVA, it will release melanin like
normal. This is a much better defense
against ultraviolet radiation.
As UVB and UVC hit the
cell’s photosensors, they
don’t respond, but when
it tries to pass through
the nucleus, the melanin
prevents it.
When UVA radiation
hits the cell’s
photosensors, it acts
like a normal cell,
only more prepared.
Random Fact
3.5 million people are DOCUMENTED each
year getting skin cancer. That means they are
most likely other cases in places where there
isn’t knowledge of skin cancer
Therefore, these two devices
Device that increases
melanosome amounts
in cells
Device that increases
melanosome activity
The Gene
The Gene that controls it is called the Ocular Albinism type
1 gene (OA1), and it controls the production in two places.
It controls the number of melanosomes produced and the
melanosomes’ activity.
The gene should be altered to produce twice the amount of
melanosome before stopping, and telling the melanosomes
to produce more.
Increasing this
protein increases
melanosome activity
OA1 Gene
ProteinRab7 and
Rab27a
Controls
melanosome
activity
ProtienCystinosin
Controls
melanosome
production
Decreasing this protein
increases melanosome
production
But the melanin still lets in 0.5% of the UV radiation, at least
This means 17,500 people will still get skin cancer each year
So how could you reduce that number?
The spores of certain types of Bacillus bacteria (such
as anthrax) can survive up to UVC radiation. If bacillus
bacteria on your skin are given DNA instructions to
form dormant spores that don’t respond to growing
conditions, you could give yourself a transparent
ultraviolet protector. The disadvantage of this is that if
the spores are kept dormant, there wont be more
bacteria, and spore production will stop.
Device for bacillus
skin bacteria to form
dormant spores
The Gene
No one really understands how the genes for this
work, other than that fact that it works. The idea
behind it is it surrounds the DNA with stuff to
absorb the radiation, similar to melanin.
The aim is to make the bacteria stay this way.
It would look something like this
Diagram of the devices working together
Key
Altered Bacillus
Dormant Spore
Melanosome
Cell
DNA+Nucleus with
the melanin coat
The bacterial spores block
most of the UV rays, and the
melanin in cells deals with
UV that passes by the spores
How to keep the spores growing
The issue with this is that if the bacterial spores don’t grow, the
bacteria producing the spores will die out, and then the spore
production stops. So instead, they should be instructed just to find
the cold months good for growing.
When the sunlight hits the
bacteria directly, with a lot
of UV radiation (such as
summer), the bacteria
spores will stop growing.
When the sunlight does
not hit the bacteria directly,
with a lot less UV radiation
(winter), the spores will
grow into bacteria.
Since the bacteria spores need to grow sometime, the
winter is best for them, with 30-60% less UV radiation. But
then you are defenseless against the other 40% (unless you
naturally have dark skin). This is why you need both. One
as your summer defense, one as your winter defense.
Possible Issues
This method of ultraviolet protection would be costly. There isn’t a
way to produce the right kind of bacillus that is safe for us (most
of the workable bacteria are anthrax related), and putting the
bacteria into producing dormant spores then they have good
conditions to grow would be really difficult.
Solutions for Possible Issues
• To produce the right kind of bacillus that is safe for us, we
would need to change its genes to make it dependent on us,
and get rid of any genes that could possibly hurt us. Either
that or we could transfer the genes that make anthrax spores
UV resistant into a safer bacteria
• To have the bacteria producing dormant spores, we would
have to instruct the bacteria so that they think that the normal
environment is not normal. This would cause them to stay as
spores.
• To keep bacteria creation going, it could be made so the
spores find the environment perfect in the fall (spring in the
southern hemisphere) and grow, but in the other season they
find the environment bad, and stop growing.