CRISPR-Cas9 Current Affairs - 2019
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Researchers from China’s Centre for Excellence in Molecular Plant Sciences have claimed to have created the world’s first single-chromosome yeast while not affecting the majority of its functions. The experiment was conducted on Brewer’s yeast having 16 chromosomes and which shares its one-third genome ancestry with humans. Researchers were able to fit nearly all genetic material of Brewer’s yeast into just one chromosome without affecting majority of its functions.
Researchers had used CRISPR-Cas9 genome-editing technology to create a single-chromosome yeast strain. Using CRISPR-Cas9, researchers removed DNA at telomeres (ends of chromosomes that protect them from degrading) and also snipped out centromeres, sequences in middle that are important to DNA replication. Firstly in this process, researchers had fused two chromosomes and then joined product to another chromosome and repeated process in successive rounds until there was only one chromosome left.
The research had revealed that number of chromosomes of eukaryote has no correlation with amount of genetic information they possess. It also showed that all genetic information can be concentrated in just one chromosome. It provides new approach to studying the functions of telomeres by simplifying complex genome system. This research may help in furthering research related to aging and diseases in humans. In future, it may also pave way for new man-made species in the future.
Scientists successfully use CRISPR to fix a genetic mutation causing Hypertrophic Cardiomyopathy disease
Scientists for the first time have successfully repaired a genetic mutation in human embryos by using a gene-editing tool called CRISPR-Cas9.
It has freed embryos of faulty DNA that causes deadly hereditary heart disease. It potentially opens the door to preventing 10,000 disorders that are passed down the generations.
Using CRISPR-Cas9 gene-editing technology, scientists were able to repair mutation in the MYBPC3 gene which causes a common heart condition called hypertrophic cardiomyopathy, which is marked by thickening of the heart muscle.
Hypertrophic cardiomyopathy is an inherited cardiac disease and the presence of even one copy of the defective gene can cause symptoms, which usually manifest as heart failure. There is currently no cure for the condition. The correction of the mutation in the embryo using CRISPR-Cas9 has ensured that the child is born healthy and the defective MYBPC3 gene is not passed on to future generations.
How it was achieved?
The CRISPR-Cas9 gene-editing tool was used to remove the genetic mutation and introduce healthy gene in sperm of man with hypertrophic cardiomyopathy. This sperm was later fertilised with eggs from 12 healthy women. It was found that 42 out of the 58 fertilised embryos did not carry the mutation. The remaining 16 embryos had unwanted additions or deletions of DNA. It showed that probability of inheriting the healthy gene increased from 50 to 72.4%.
CRISPR-Cas9 gene-editing technology
Using CRISPR system, scientists can remove, add or alter specific DNA sequences in the genome of higher organisms. It has two components, a single-guide RNA (sgRNA) that contains a sequence that can bind to DNA, and Cas9 enzyme which acts as a molecular scissor that can cut specific DNA sequence. In order to selectively edit a desired sequence in DNA, the sgRNA is designed to find and bind to the target.