Saturday , June 19 2021

What is CRISPR-Cas9? The revolutionary gene-editing tech



Until you want to, say, a dry resistant corn plant, your options are very limited. You can try for selective breeding, try sedimentation in the hope of a beneficial change, or try to completely insert a snap of DNA from another organism.

But these were long-winded, impatient or expensive – and sometimes all three at once. Enter CRISPR. Precise and inexpensive to produce, this small molecule can be programmed to direct the DNA of organisms to the specific genes.

The development of cheap, relatively easy gene editing has opened a smash board of new scientific capabilities. In the United States, CRISPR-acquired long-life podcasts have already been approved by the authorities, while elsewhere researchers are exploring sharp tomatoes and peach-flavored strawberries.

However, the game-changing technology can have the greatest impact when it comes to human health. If we cause the troublesome mutations to cause them genetic diseases – such as hemophilia and disease-anemia anemia – we can all end them. The pathway for human gene editing is contrasted with controversy and fierce label dilemma, however, as the news in the end of 2018 that – against all ethical guidance – a Cynical scientist set the first gene-edited babies.

Here is everything you need to know about the complex and sometimes controversial technology that carries the next edition revolution.

What is CRISPR?

CRISPR developed as a way for some types of bacteria to defend against viral invaders. Each time they visited a new virus, DNA snaps were extracted from that virus and made a copy to store their own DNA. "They collect a set of sequins that they've experimented with," says Malcolm White, a biologist at the University of St. Andrews, & # 39; this [bacteria] Essentially, a small library brings them into their genome. "

To send the library analogue, these scraps of viral DNA are as small books – each containing the data that they laugh at and the successful removal of a virus is losing its success. And in-between these useful DNA stones are some smaller useful songs of repetitive DNA that kept them angry – like a kind of molecular book.

These repetitive segments of DNA give CRISPR its name – Clustered Regularly Interspaced Short Palindromic Repeat – but it's really the bits between this repetition that makes CRISPR so useful. These useful bits are called awkward as spasters, and each one has a reference to the DNA of a file that came with the backlinks (or their ancestors) in the past. If a previously unknown virus is in the back, add another spacer to its library of earlier attacks.

If a virus of the same species attacks again, the spacer will match that virus & # 39; common swinget in action. It's a little bit like the way our own immune systems can recognize a grypirus when we have vaccinated the year. The spacer session has been changed to RNA – a molecule that contains DNA messages – and hunts the comparative piece of viral DNA. Once, it finds an enzyme present in an RNA string as a few biological strands, the waste of the target group and the removal of & # 39; e virus harmless.

You have heard the system called CRISPR-Cas9 and just CRISPR. In this case, the Cas9 bit refers to the enzyme used to cut the target group. "We can program [Cas9] It makes it easy to influence and be very specific to one DNA session, so it won't say what is going on, "White says. Other types of enzymes can be affected in gene editing – Cas12 and Cpf1 – but they all work on the same basis.

How does it work

Of course this is all useful only if you are a baker. So how can we make an anti-virus definition mechanism in one thing, which can allow our human take part?

Instead of cracking down on the molecules for them, scientists have worked out what their own versions of CRISPR molecules do in & # 39; to create a life. To get started, they need to run the sector of the DNA they want to target. For a conditional disease anemia, caused by a mishap in a single gene, this is relatively easy, if we have already done the gene that will cause this disease and exactly that genetic code knows we are trying.

The banana is star. The races are new to the race before it's too late

Before going to the business to relax and regenerate DNA, it's worth dealing with how DNA is structured. Gather the well-known DNA double helix together for four different starbursts: adenine (A), thymine (T), guanine (G) and cytosine (C). Setting up these bases determines everything about us, genetic talk. Egg color, although we are very likely, whether we are business-specific for certain diseases, is already written in basic pears in our genetic code.

Like teeth on a zipper, this base is always with their complementary base. Always on the road with T, while G always has a few more pairs with C, until you get the three billion few pairs that's the human genome.

But DNA is not much use to block in a double helix – it has to be that information is extracted from and inside where it can be used to generate proteins; the building blocks of all are everything in our bodies. To do this, DNA originates from itself, breaking this base pair breaks down until it hits the cell.

These fluttering, previously unfathomable basic pears fit with short segments of RNA that are their own base. RNA shares three bases with DNA – G, C and A – but T is always replaced by U (uracil). Apply Comparative Basic Forming Rules so that an exposing DNA G base can with an RNA C base can act as a DNA base with a U. For example, if you have an exposing DNA sequence of GAC, you will be using an RNA gene. order of CUG.

Scientists use these basic principles to make their own CRISPR molecules that, if we show above, are short strings of RNA. All you need is a region of interesting DNA – like the bit that contains the mutation that leads to disease-anemia – and offers the complementary RNA session, offering DNA-hopping enzyme. It is a bit like beginning with one side of a touch and its use to build the matching but opposite side of the repair that's just & # 39; e pass is.

Once you've got CRISPR molecules, you need to get them targeted. Fortunately, the virus does not prevent the injection of pieces into other cells, so that CRISPR molecules in other good viruses, is one particularly useful way to introduce CRISPR into cells that have already been done with many mouse studies .

Now CRISPR-Cas9 can really work. The Cas9 enzyme starts with relaxing bits from the DNA double helix, while the RNA molecule is in & # 39; run from the exhibited base pair to a perfect match. Once the complete match is found, Cas9 writes the problems to repairing the remaining DNA bits. Other enzymes can be added in genes instead of deletion, but the basic process of relaxation, work, and manipulation remains the same with other CRISPR molecules.

What is CRISPR used for?

CRISPR is particularly attractive to the agricultural business, which is always looking for an engineer of disease- and water-resistant crops that will increase the yield and, subsequently, their profit margins. In October 2015, biologists at Pennsylvania State University produced US regulators with button problems that were claimed by US US Department of Agriculture (USDA) regulators to slow down white bronze than normal pills.

A year later, the USDA suggested that the same pillars be cultivated and sold without going through the bureau's regulatory process for genetically modified foods. Now, brownish podiums are hardly the most exciting food, but this USDA is a huge amount to say that CRISPR-edited cultures are some of the & # 39; s neighborhoods of & # 39; upgrading the environmental level.

And it's not exactly rashes that get the CRISPR love. In Australia, one scientist has already used CRISPR to make bananas resistant to a lethal fungus that is prone to covering the world's inflammation, while others work on the use of the technology for naturally-decaffeinated coffee to make or finally the engineer the perfect logo.

Timeline: When was CRISPR discovered?


2005
After characterizing CRISPR in 1993, Francisco Mojica at Alicante University in Spain became the first for hypothesis that DNA sequins are part of the adaptive immune system of bacteria.
2007
Scientists at Danisco, a mathematical research association, have suggested that CRISPR is part of a bacterial immune system and that Cas9 deactivates the importing virus.
2011
Emmanuelle Charpentier & # 39; s group at Umeå University in Sweden shows the role of tracerRNA in leading Cas9 to his cellular goal.
2012
Emmanuelle Charpentier and Jennifer Doudna at California University, reaching Berkeley reach the CRISPR system by merging several elements into one, synthetic guide

Although the agricultural world offers some of the furthest examples of CRISPR in action, the points are much higher than human health issues. Animal studies are already in place to use CRISPR for disease-anemia and hemophilia – two promotional candidates for CRISPR treatment are not defined by a relatively small number of mutations. In the case of cyclone cellular conditions, the condition is caused only by the mutation of a single-based pair in one gene.

The more genes involved in a condition, the hard it becomes to use CRISPR as a potential solution. "There are not many human-animal animals where" "one gene is mutated," White says. Certain cancer, for example, are linked to multiple mutations in different genes, and often the link between genetic mutations and cancer risk is poorly understood so that we can use CRISPR to fix defective genes – that would be 39; d become a kind of panacea for cancer.

Why is CRISPR controversy?

Last year, He Jiankui, a researcher at the Southern University of Science and Technology in Shenzhen, swallowed the scientific world when he found responsibility for the first world power of a CRISPR-acquired world. He ebreds messages from couples that caused the father to be HIV-positive and the mother HIV-negative and uses CRISPR to manage it sufficiently for many channels that HIV uses to deal with cells.

The experiment – detailed in a YouTube video climate, not a peer-reviewed magazine – was extensively condemned by scientists. "It has been widely recognized that science is not yet ready for clinical use," says Sarah Chan, a biotechnologist and director of the Mason Institute for Medicine, Life Sciences and Law at Edinburgh University. "Make more to solve uncertainty, and try and understand the risks."

Although the He Study has clearly elaborated on ethical boundaries, it will be one of the major ethical concerns of CRISPR. The problem is that it is not easy to use CRISPR to change your genome if you are an adult – you have to find a lot that you select the molecules in each single goal.

This may be possible for conditions such as cell-cell anemia, where you should only change the DNA in red blood cells. By using CRISPR to change the node work – where red blood cells are produced – you can visit a relatively small percentage of cells and still determine the condition.

But if you want to change the whole genome of a person, you need to create their DNA when they are smaller than a small cluster of cells. This leads to all kinds of ethical problems. Why stop identifying and degrading genetic diseases, for example, if we would also have an embryo DNA, can the results appear to be more intelligent or good-looking?

"What do we want to change the future life span, or intelligence, or breathing of Alzheimer's or if they are cold when they come to middle-aged," White says. "The social concerns have to deal with what we want – it's not the scientists."

Although man's inclination is something of the greatest ethical question, things are not clearer than when it comes to agriculture. In July 1018, the European Court of Justice called into question the future of genetically engineered cultures as it confirmed that CRISPR edition cultures were not to receive existing schemes that restrict the cultivation and sale of genetically modified bodies.

Cultures that have been genetically modified – mostly by setting a gene from one organ to another – have long been rare in Europe, despite their population in other parts of the world. In spite of a scientific consensus that GM food is safe to eat, warning of frank food & # 39; and lobbying environmental groups helps to keep GM cultures away from a human consumption.

But agricultural lawyers for CRISPR hope that the new gene editing technology would make it possible to reach this equilibrium. The EKJ direction means that all CRISPR editors that have grown or sold in the growth have to carry stringent security tests that make non-edited crops (or cultures using technical techniques such as radiation mutation). ). Now, at least, one of the biggest events that CRISPR is is not science, but public relations.

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