Life & Medical ScienceWorld

Scientists Killed A Mosquito Population By Hacking Their DNA

It might be a shocking fact that mosquito is the most deadliest animal surviving with us . But that’s true ! . Killing over millions of people every year these small creatures can’t be ignored at any level. They are the major disease causing creatures and we must care ourself to get rid of them.

Have you ever thought that is there any thing that can save us from them for longer or can we get rid of them by reducing their quantity so that no more mosquito could survive and and no more cases of dengue, malaria come out to be heard?. Well ! It seems to be possible now.

New research suggests we could wipe the destructive buggers off the map using a genetic engineering technique known as a gene drive — if we’re willing to risk permanently altering our ecosystem.

A gene drive lets researchers make a change to one organism that it then passes down to its offspring, like a genetic time bomb. Using the technique, researchers from Imperial College London completely wiped out a caged population of Anopheles gambiae, the mosquito species that spreads malaria in sub-Saharan Africa.

In accordance with the study, published on Monday in the journal Nature Biotechnology, the researchers used CRISPR to modify the gene responsible for determining sex in 150 male mosquitoes. That alteration made the male gene dominant — the idea was, over time, that the population would stop producing females, driving them to collapse.

The researchers added these genetically altered mosquitoes to a caged population of 450 unaltered male and female mosquitoes to reproduce with them. The hack worked: Subsequent generations of females exhibited male and female characteristics, couldn’t bite, and couldn’t lay eggs. By the eighth generation, there were no longer any females in the population at all.

WHAT IS CRISPR ?

CRISPR  is a family of DNA sequences in bacteria and archaea. The sequences contain snippets of DNA from viruses that have attacked the prokaryote. These snippets are used by the prokaryote to detect and destroy DNA from similar viruses during subsequent attacks. These sequences play a key role in a prokaryotic defense system,and form the basis of a technology known as CRISPR/Cas9 that effectively and specifically changes genes within organisms.

CRISPR is an abbreviation of Clustered Regularly Interspaced Short Palindromic Repeats. The name was minted at a time when the origin and use of the interspacing subsequences were not known. At that time the CRISPRs were described as segments of prokaryotic DNA containing short, repetitive base sequences. In a palindromic repeat, the sequence of nucleotides is the same in both directions. Each repetition is followed by short segments of spacer DNA from previous exposures to foreign DNA .Small clusters of cas (CRISPR-associated) genes are located next to CRISPR sequences.

The CRISPR/Cas system is a prokaryotic immune system that confers resistance to foreign genetic elements such as those present within plasmids and phages that provides a form of acquired immunity. RNA harboring the spacer sequence helps Cas (CRISPR-associated) proteins recognize and cut exogenous DNA. Other RNA-guided Cas proteins cut foreign RNA. CRISPRs are found in approximately 50% of sequenced bacterial genomes and nearly 90% of sequenced archaea.

GENE EDITING TO REMOVE MOSQUITOES

Genome editing (also called gene editing) is a group of technologies that give scientists the ability to change an organism’s DNA. These technologies allow genetic material to be added, removed, or altered at particular locations in the genome. Several approaches to genome editing have been developed.

A recent one is known as CRISPR-Cas9, which is short for clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9. The CRISPR-Cas9 system has generated a lot of excitement in the scientific community because it is faster, cheaper, more accurate, and more efficient than other existing genome editing methods.

Most of the changes introduced with genome editing are limited to somatic cells, which are cells other than egg and sperm cells. These changes affect only certain tissues and are not passed from one generation to the next. However, changes made to genes in egg or sperm cells (germline cells) or in the genes of an embryo could be passed to future generations. Germline cell and embryo genome editing bring up a number of ethical challenges, including whether it would be permissible to use this technology to enhance normal human traits (such as height or intelligence).

 

MORE ABOUT STUDY

The team, led by Andrea Crisanti from Imperial College London, developed a new “gene drive,” which spreads specific genes through a population over generations. The introduced gene targeted the pathways relating to sex determination—essentially, they stopped females from being produced within seven to 11 generations. Findings were published in the journal Nature Biotechnology.

Malaria kills more than 1 million people every year, mostly children under the age of 5. Ninety percent of all cases are in sub-Saharan Africa. It is caused by the parasite plasmodium and spread via certain species of mosquito. Female mosquitoes pick up the parasite from infected people when they bite them. The parasite then reproduces and develops inside the mosquito. When the mosquito bites again, the parasite is transferred.

Finding a way to prevent the spread of malaria is extremely difficult. Experts across the globe are working on malaria vaccines but progress has been slow, and so far, those in development have had relatively low efficacy.

“It is estimated in the best-case scenario that with available technology and significant increase in funding, it will take another 30 to 40 years to eradicate malaria,” Crisanti told Newsweek. “Gene drive may significantly expedite the achievement of this objective.”

In the latest study, scientists targeted a gene called doublesex, which determines whether a mosquito becomes male or female. Researchers altered the gene so that females with two copies of the gene showed male and female traits. They failed to bite and did not lay eggs. The gene spread quickly, and after eight generations, no females were produced and the population collapsed. What’s more, the mosquitoes did not develop a resistance.

The experiment was carried out in a laboratory, and the authors said that field testing would now be required to find out what happened in a more natural setting. Crisanti said it would be five to 10 years before they would consider testing this technology in the wild but that the discovery was “encouraging proof” that they were on the right track.

“Past experience has demonstrated that eliminating a few mosquito species from the environment does not cause ecological havoc,” she said, adding that before any testing took place they would assess the biology and effectiveness of the gene drive under confined conditions mimicking tropical environments. They would also investigate the food webs that involve the malaria mosquito to identify prey and predators.

Fred Gould, distinguished professor of entomology at North Carolina State University, who was not involved in the study, said the results were very promising. “This is a big step forward,” he told Newsweek. “There was huge excitement over using CRISPR for gene drive to fight malaria, but in the first studies the mosquitoes evolved resistance to the drive very quickly. The innovative approach used in this study suggests a way around the problem of resistance. If the drive mechanism functions under diverse environmental conditions and resistance doesn’t evolve when this approach is used on a larger experimental scale, this will be a major breakthrough on the road to suppression of malaria.”

SOURCE – Futurism

 

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