CRISPR or (Clustered Regularly Interspaced Short Palindromic Repeats) is a group of DNA sequences situated within the genes of prokaryotic viruses such as bacteria. CRISPR-Cas9 technology uses an enzyme (Cas9) that acts as a molecular clipper to cut DNA strands of the invading bacterial viruses. This enabled scientists to easily target the immune defense mechanism and modify DNA sequences through providing a copy of the DNA sequence called “RNA Guide” to direct Cas9 to edit and cut the targeted DNA strand .Subsequently, scientists could apply their techniques and modify parts of this specific organism’s genome.
For further illustration, let’s take a look how scientists
De-extinct a passenger pigeon using CRISPR-Csa9.
Firstly, Scientists work by obtaining a genome of a currently living similar organism and in this case, the band tail pigeon’s genome 97% best matches passenger pigeons genomes. The 3% difference is caused by the numbers mutations that have been attained and passed down by these species over millions of years. Since the reference genome of the band-tailed pigeon is 1.1 billion base pairs of genetic code. Scientists would transcribe the cell function and identify parts of the code used to regulate cell functions and create RNA traits from the organism that needs to be sequenced .Afterwards these DNA controlling traits are transcribed into RNA
The process takes place inside the cytoplasm cells specifically in the ribosome that will control these traits and utilize them in making proteins through (protein synthesis) as well as controlling how much protein should be produced. All these elements in the genome are processed through an intermediate RNA stage known as the transcriptome. As Birds genomes contain 17,000 encoded elements interspersed on different chromosomes, different tissues in their bodies express different subsets of these genes therefore to discover and map them all scientists sequence RNA from multiple tissues. Once the RNA is sequenced, the resulting reads can be mapped to the DNA reference assembly to identify and map the positions of genes and regulating elements. Accordingly, after information is obtained, we compare and contrast the differences between the genomes of the two pigeons. Once the differences are identified, codes will be synthesized through a process known as DNA printing – making the genetic code into viable DNA molecules that can be utilized to edit the genomes of band tailed pigeons
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Finally,The primordial germ cells in the Band tailed pigeon are isolated from its embryo, then grown in a culture where they are engineered. That’s when the Crispr-cas9 gene comes handy and uses its function to cut off the band-tailed pigeon’s gene where the homologous recombination (the cell’s own DNA repair mechanism) inserts the passenger pigeon gene. Now the band-tailed primordial germ cell edits passenger pigeon genes. These engineered paramedical germ cells are then injected into the embryo of the passenger pigeon where they migrate to the gonads. A germ-line chimera develops, although the tissues are made of the band-tailed pigeon, but the gonads will host a population of sperm or eggs that is made up of native band-tailed pigeon cells with the injected a portion of the engineered cells. Once a male and a female band pigeon mate they will produce three types of offspring: pure band-tailed pigeons, band-tail-passenger pigeon hybrids, and lastly ( asthe engineered sperm meets the engineered egg cell) a fully formed de-extinct passenger pigeon.
Cons
Although de-extinction seems to be the solution to all the problems, there are many downsides that come with it too. Let’s consider the environmental factors as animals generally need the fitting ecosystem to survive. Our environment has drastically evolved and is still. Scientists and ecologists have addressed the issue that reviving extinct animals could possibly be a bad idea as they won’t able to survive in our natural eco-system, alternatively, we should focus on saving endangered animals. Animal's ecosystem consists of all biotic and abiotic components that are linked together in inseparable way that an animal should adapt in order to survive. Scientists examined passenger pigeon genome and discovered that he had high genetic diversity, indicating they had lived as a very large population for a very long time so bringing them back would be a death sentence.
With all major issues our earth is witnessing like climate change, global warming, and human activities that highly disturbed the natural habitat, bringing back a species into an environment totally different from the one they once lived in would be an impractical idea . It is a fact that the majority of extinct species went extinct not because they were killed , but because their habitat disappeared ,Consequently , it is impossible to find an environment to suit those species’ needs .
Pros
There are positive aspects for this solution too .Scientifically speaking we can save up 0.1% of species yearly via de-extinction. We can’t deny the fact that bringing extinct species back to life increases biodiversity, fulfills missing ecological niches and important for the overall functioning of an ecosystem. For example the giant ground-sloths fed on large foods and nuts, these fruits and nuts such as avocados relied on those sloths for seed dispersal, Passenger Pigeon is known as the ecosystem engineer sewing different parts of habitat dynamics that eastern biomes depend on on. By de-extinction many animals could help restore long lost ecological patterns.
Conclusion
CRISPR cas-9 technology is far more accurate than other techniques such as cloning that produce genetically analogous organism through asexual reproduction .Cloning has a 40% chance of working compared to CRISPR. . Not onlyUsing CRISPR-Cas9 technology will reduce unintended mutations and unwanted errors it also proved to be more practical and efficient comparing to other techniques used to de-extinct animals.
Finally, despite the environmental disadvantages, these problems would resolve over time once humans map out some environments that could potentially be similar to the extinct animal’s previous environment. Furthermore, he ecological benefits this process has to offer definitely override the disadvantages and CRISPR-Cas9 should definitely be used to de-extinct animals.