




















More from Health
1/16
Why do B12 and folate deficiencies lead to HUGE red blood cells?
And, if the issue is DNA synthesis, why are red blood cells (which don't have DNA) the key cell line affected?
For answers, we'll have to go back a few billion years.
2/
RNA came first. Then, ~3-4 billion years ago, DNA emerged.
Among their differences:
🔹RNA contains uracil
🔹DNA contains thymine
But why does DNA contains thymine (T) instead of uracil (U)?
https://t.co/XlxT6cLLXg
3/
🔑Cytosine (C) can undergo spontaneous deamination to uracil (U).
In the RNA world, this meant that U could appear intensionally or unintentionally. This is clearly problematic. How can you repair RNA when you can't tell if something is an error?
https://t.co/bIZGviHBUc
4/
DNA's use of T instead of U means that spontaneous C → U deamination can be corrected without worry that an intentional U is being removed.
DNA requires greater stability than RNA so the transition to a thymine-based structure was beneficial.
https://t.co/bIZGviHBUc
5/
Let's return to megaloblastic anemia secondary to B12 or folate deficiency.
When either is severely deficient deoxythymidine monophosphate (dTMP*) production is hindered. With less dTMP, DNA synthesis is abnormal.
[*Note: thymine is the base in dTMP]
https://t.co/AnDUtKkbZh
Why do B12 and folate deficiencies lead to HUGE red blood cells?
And, if the issue is DNA synthesis, why are red blood cells (which don't have DNA) the key cell line affected?
For answers, we'll have to go back a few billion years.

2/
RNA came first. Then, ~3-4 billion years ago, DNA emerged.
Among their differences:
🔹RNA contains uracil
🔹DNA contains thymine
But why does DNA contains thymine (T) instead of uracil (U)?
https://t.co/XlxT6cLLXg

3/
🔑Cytosine (C) can undergo spontaneous deamination to uracil (U).
In the RNA world, this meant that U could appear intensionally or unintentionally. This is clearly problematic. How can you repair RNA when you can't tell if something is an error?
https://t.co/bIZGviHBUc

4/
DNA's use of T instead of U means that spontaneous C → U deamination can be corrected without worry that an intentional U is being removed.
DNA requires greater stability than RNA so the transition to a thymine-based structure was beneficial.
https://t.co/bIZGviHBUc

5/
Let's return to megaloblastic anemia secondary to B12 or folate deficiency.
When either is severely deficient deoxythymidine monophosphate (dTMP*) production is hindered. With less dTMP, DNA synthesis is abnormal.
[*Note: thymine is the base in dTMP]
https://t.co/AnDUtKkbZh

You May Also Like
1. Project 1742 (EcoHealth/DTRA)
Risks of bat-borne zoonotic diseases in Western Asia
Duration: 24/10/2018-23 /10/2019
Funding: $71,500
@dgaytandzhieva
https://t.co/680CdD8uug
2. Bat Virus Database
Access to the database is limited only to those scientists participating in our ‘Bats and Coronaviruses’ project
Our intention is to eventually open up this database to the larger scientific community
https://t.co/mPn7b9HM48
3. EcoHealth Alliance & DTRA Asking for Trouble
One Health research project focused on characterizing bat diversity, bat coronavirus diversity and the risk of bat-borne zoonotic disease emergence in the region.
https://t.co/u6aUeWBGEN
4. Phelps, Olival, Epstein, Karesh - EcoHealth/DTRA
5, Methods and Expected Outcomes
(Unexpected Outcome = New Coronavirus Pandemic)
Risks of bat-borne zoonotic diseases in Western Asia
Duration: 24/10/2018-23 /10/2019
Funding: $71,500
@dgaytandzhieva
https://t.co/680CdD8uug

2. Bat Virus Database
Access to the database is limited only to those scientists participating in our ‘Bats and Coronaviruses’ project
Our intention is to eventually open up this database to the larger scientific community
https://t.co/mPn7b9HM48

3. EcoHealth Alliance & DTRA Asking for Trouble
One Health research project focused on characterizing bat diversity, bat coronavirus diversity and the risk of bat-borne zoonotic disease emergence in the region.
https://t.co/u6aUeWBGEN

4. Phelps, Olival, Epstein, Karesh - EcoHealth/DTRA

5, Methods and Expected Outcomes
(Unexpected Outcome = New Coronavirus Pandemic)
