In this case, once something abnormal is happening to the chromosome, it will affect the body's function. Scientists have been trying to unravel the secrets hidden by all chromosomes, and chromosome 20 caught their attention in the process.

The human body has 3 pairs of chromosome , which hides the human body's genetic material and is the vector of genes. In this case, once something abnormal occurs in the chromosome, it will affect the body's function .

Human "life code" - chromosome

Scientists have always been trying to unravel the secrets hidden by all chromosomes, and in this process 0 chromosome caught their attention.

It turns out that there is a "God's Forbidden" on human chromosome 20. So, what is this ban? What is it stopping humans from doing?

How many secrets do we don’t know on the chromosome?

Chromosome 20

First, let’s first understand the basic situation of 0 chromosome . As a pair of autosome , 0 tricolor contains 63, 025, and 520 base pairs , the number of genes is 938, 537 inhibitory protein-encoded genes, and 7 abnormal protein-encoded genes.

shows that chromosome 20 is still very important, and according to scientists' research, its abnormalities are related to many genes.

chromosome 20

For example, in hematologic diseases, myelodysplastic syndrome , leukemia , diabetes , colorectal cancer, Alzheimer's disease, etc. These diseases often involve multiple systems, and they are more or less related to some abnormal manifestations of chromosome 20 .

In terms of the blood system, chromosome abnormalities No. 20 are common structures for malignant hematologic diseases. Common chromosome deletion sites are del(20) (q11.2, q13.1) and del(20) (q11.2, q13.3).

data shows that Reid et al. conducted G-band analysis on bone marrow samples of 9 patients with acute stage of chronic myeloid leukemia and found that there were different sizes of long arm fragments of chromosome 20 in 9 patients.

chromosome mutation diagram

In addition, scientists also found through research that 0 chromosome has two genes that increase the risk of male baldness . Of course, it would be fine if these two genes are normal. The problem is that according to the research results, the probability of mutating is very high.

In addition to the above common discoveries and studies, what scientists are most concerned about is the "God's ban" on chromosome 20, which is exactly the PRNP gene .

PRNP gene present on chromosome 20

PRNP gene and prion

Before formally introducing this gene, we must first know what prion is.

prions are also known as infectious spongy encephalopathy and are fatal neurodegenerative diseases . Generally speaking, the probability of human prions is very low and the incidence is also very low, ranging from about 1 to 3 cases per million people per year.

However, the incubation period of this virus is very long, and the mortality rate of can reach 100% , so although the incidence rate is very low, it is still very important.

The prion is helpless after infection

So, what exactly is prion? How to get infected with prions?

In fact, in the last century, American neurologist Prusina had discovered prion when she was studying sheep scrapie, and later won the Nobel Prize for the discovery of prions.

chromosome in human is also considered to be the "code of life" in essence a natural disordered protein that can be folded into a stable form through a special means. When two unstable intermediates with the same configuration combine, prion will be formed.

prion structure diagram

and the probability of this self-templating is very low unless we ingest similar substances from the outside world . In short, it is through "" " .

cannibal seems to be a character in urban legends for everyone, but in fact, there have indeed been large-scale "cannibalism" incidents in human history.

data shows that prion infection mainly causes the death of central nervous cells. The necessary condition for infection is that central nervous cells express prion protein, which is an protein that has the same amino acid sequence as prion but has a different secondary conformation.

The brain infected with prions

Perhaps in order not to allow humans to push themselves to the path of extinction in this way, PRNP gene appeared, and 's function is to fight prions and help people survive disasters .

However, the PRNP gene is not omnipotent. If cannibalism is too serious, then it cannot save .

PRNP

on cell membrane Therefore, everyone can regard the PRNP gene as the last trump card left to humans by God. , but since its resistance is not 100%, it is also like a God's ban or warning .

's purpose is to tell later humans that our ancestors had experienced such a disaster in the past. warns us not to think about attacking similar people, otherwise the "prion outbreak" disaster will repeat .

Prion in E. coli

It is worth mentioning that prions are not a "minefield" set by gods for humans. Other animals are also troubled by it. , such as cattle, sheep, deer, mink, etc., have all been infected with prions .

Among them, the prion infection incident in cattle should be the most familiar one, because mad cow disease is caused by it.

Adult cows who died of mad cow disease

When the first mad cow disease occurred in the UK in the 1980s, people were in panic. And according to the subsequent situation, the infectious disease of in the herd became more and more severe, and the infection of cattle even exceeded 2 million .

But, how could a cow that was originally eating herbivorous suddenly run to eat the same kind of meat?

Terrible mad cow disease epidemic

This is because the farm gave cattle some meat and bone meal containing bovine prion , which inadvertently made prion infection meet the conditions . Therefore, the emergence of mad cow disease is actually due to human reasons.

study found that the polymorphism of the bovine prion gene has a certain impact on mad cow disease virus infection. These polymorphic genes include mutations in the 23 -base pairs in the upstream promoter region of PRNP and mutations in the 12-base pairs in the first intron.

Number

When suffering from mad cow disease and cannot stand, then, what will the prions that look inconspicuous but are actually particularly terrifying, develop in the future? Will it be slowly eliminated in the natural environment?

The future development trend of prions

Although people were shocked by mad cow disease at the end of the last century, still successfully ended the disaster with relevant tough measures . Moreover, when the consumption of meat and bone meal is prohibited, animal prion infection has been significantly alleviated worldwide.

However, it is impossible to completely eliminate it in the natural environment, because the infection pathway of prions under natural conditions has long existed, and can even bind soil particles to spread the virus further away.

Schematic diagram of the transmission process of prions

Speaking of this, many fans of the "doomsday zombie culture" should have a breath. After all, the infection symptoms of prions are indeed very similar to the so-called zombies. Coupled with this super contagious power, this means it is not difficult for this virus to spread.

Of course, logically speaking, the transmission barrier between different species of can prevent its from spreading across species , but everything is always unexpected. Therefore, in these accidents, will give birth to a brand new strain , and these strains can eventually be passed on between species and become the real "death scythe".

Prions in mouse neurons (red part)

This is also why the probability of prions is low, but scientists seem very alert. Because as mentioned above, prion infection in other animals in may eventually break through the interspecies barrier, and is transmitted to human . This means that even if everyone can "not eat people" in a civilized society, there is still a chance of prions breaking out.

It is worth mentioning that when everyone focuses on the huge disaster brought by prions, some scientists discovered that this guy actually appeared very early. prions already existed in as early as the early stages of life evolution. At that time, it not only did not cause "unrest", but also played an important role.

biological evolution process diagram

"Double-sided prion"

It turns out that scientists have found through research that prion protein can give organisms the ability to quickly adapt to the environment .

You should know that in that difficult era, whoever has strong adaptability can survive smoothly, and , and in our eyes, the prions that turn the brain into a "sponge" actually have the ability to help life accept natural selection .

To verify this problem, scientists specially conducted yeast experiments and found that when the external environment changes, the prion protein in yeast will become a new form, . This change is to help yeast use new foods and adapt to the new environment . Moreover, this adaptability is actually hereditable.

prion protein diagram

Therefore, scientists will not only place prions in their research, but hope to discover some of its functions. In this case, some prions that have positive effects in organisms are found one after another, and they are even the key to organisms in forming long-term memory .