Albino lizards write history as & # 39; the world's first gene-processed reptiles made by scientists
- Reptiles have long been a problem for scientists who process genes
- The way reptiles reproduce means that traditional CRISPR techniques are not effective
- Researchers from the University of Georgia have found a way to adjust the method and change reptile eggs that are about to be fertilized
Scientists have finally succeeded in making gene-processed reptiles – with albino lizards the size of a human index finger, the first ever made.
Geneticists have difficulty using the powerful CRISPR gene editing program on reptiles because of the way they reproduce.
But a few changes to the method allowed them to successfully change the lizard genes.
They chose to make the albino of the animal because it is an obvious mutation that does not harm the animal, and secondly it could help to treat vision problems in humans.
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Geneticists have difficulty using the powerful CRISPR gene processing program on reptiles because of the way they reproduce, but University of Georgia researchers have modified the existing CRISPR and had a success rate of six – nine percent
Researchers from the University of Georgia have adapted the existing CRISPR method for reptiles.
It was previously thought that CRISPR would not work because it must be injected directly into freshly fertilized eggs or single-cell zygotes.
However, lizards fertilize in the body at unpredictable moments.
Moving single-cell embryos from women is also fraught with problems and they are notoriously difficult to manipulate in a laboratory environment.
But a new method, described in the journal Cell, delayed the procedure as lizard eggs – or unfertilized egg cells – develop.
They saw a transparent membrane over their ovaries so that they could see all developing eggs, including which eggs would then be ovulated and fertilized.
They decided to inject the CRISPR reagents into the unfertilized eggs in the ovaries and see if it would work.
Study the corresponding author Dr. Doug Menke, an associate professor at the University of Georgia, said: & # 39; We have been struggling for some time to modify reptiles genes and genes in reptiles, but we are stuck in the mode of how gene processing is done in major model systems .
& # 39; We wanted to explore anole lizards to study the evolution of gene regulation, as they have witnessed a series of speciation events on the Caribbean islands, just like Darwin's finches of the Galapagos.
& # 39; Because we inject unfertilized eggs, we thought we could only perform gene processing on the alleles inherited from the mother.
A few changes to the mammalian CRISPR method allowed them to successfully change the lizard genes. They chose to make the animal's albino because it is a clear mutation that does not harm the animal, and secondly it could help to treat vision problems in humans (stock)
& # 39; Paternal DNA is not in these unfertilized ova. We had to wait three months for the lizards to come out, so it looks a bit like slow-motion gene editing.
& # 39; But it appears that when we did this procedure, about half of the mutant lizards that we had generated had gene editing events on the parent allele and paternal allele. & # 39;
Approximately between six and nine percent of the eggs created some offspring that were gene processed.
Professor Menke acknowledged the shortcomings of the procedure, especially in comparison with the CRISPR juggernaut in mammals.
He said: & # 39; Compared to the very established model systems with an efficiency of up to 80 percent or higher, six percent seems low, but nobody has been able to do this type of manipulation in a reptile before.
& # 39; There is no large community of developmental geneticists studying reptiles, so we hope to be able to use exciting functional biology that has not yet been discovered. & # 39;
WHAT IS CRISPR-CAS9?
CRISPR-Cas9 is a tool for the accurate processing of DNA discovered in bacteria.
The acronym stands for & # 39; Clustered Regularly Inter-Spaced Palindromic Repeats & # 39 ;.
The technique includes a DNA cutting enzyme and a small tag that tells the enzyme where to cut.
The CRISPR / Cas9 technique uses tags that identify the location of the mutation, and an enzyme that acts as a small pair of scissors to cut DNA in a precise location, allowing small parts of a gene to be removed
By editing this tag, scientists can target the enzyme to specific DNA regions and cut exactly where they want.
It has been used to silence & # 39; genes & # 39; – effectively disable them.
When cellular machines repair the DNA break, it removes a small piece of DNA.
In this way researchers can precisely switch off specific genes in the genome.
The approach has previously been used to process the HBB gene responsible for a condition called β-thalassemia.
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