Immune system is one of the most important parts of our body that protects us from viruses and bacteria. There are two ways for our immune system to work. First is killing the foreign bodies inside the cell by using reactive oxygen species (ozone, hydrogen peroxide, bleach, etc), which are produced by enzyme NOX2, and the second is killing them outside the cell, using poisonous net composed by DNA called “neutrophil extracellular traps” (NETS).
People thought that the ways of how immune system works was only in human and other complex animals. However, the microbiologists from University of Geneva (UNIGE) discovered that the social amoeba, an unicellular organism, has a similar way of protecting its body from foreign bodies with human. Usually, these microorganisms survive by eating bacteria as a main source of food. When the food runs out, they gather together and make a slug-like mini animal with lots of pores and survive until the wind or other factors to move them to a new place. To make this slug, 20% of the cell sacrifice themselves in order to make the other 80% into pores. However, there is still 1% remaining keeps its phagocytic functions. “This last percentage is made up of cells called “sentinel” cells. They make up the primitive innate immune system of the slug and play the same role as immune cells in animals, “ explains Thierry Soldati, last author of the study.
As explained in the first paragraph, our immune system uses poisonous DNA nets to kill foreign bodies. According to the study of Soldati and his colleagues in Geneva and the Baylor College of Medicine in Houston, Texas, the social ameoba’s immune systems (sentinel cells) can also produce the DNA-based extracellular traps (ETS) to kill foreign bodies.
This study has great impact for the medical study of the diseases related to humman’s immune system, such as leukemia and chronic granulomatous disease (CGD). Patients with CGD are unable to produce normal enzyme NOX2 and therefore, they suffer lots of diseases even though they are easy to be cured because their immune systme cannot work properly. Now, by modifying and changing the DNA of this microrganism, scientists can do all kinds of experiments that can be adapted to human beings more easily. Thus, by using Dictyostelium discoideum (scientific name of the slug) to find the genetic disorder in immune systmem, scientist will be able to open a new way to find the treatment.
A team of scientists from the Institute of Neuroscience at the Chinese Academy of Sciences in Shanghai, has genetically modified monkeys in order to create a better model for studying autism.
The team has introduced a human gene called MECP2, which people with autism symptoms have extra copies of, into the monkeys’ DNA. This caused the monkeys to display at least one symptom related to autism, like repetitive movements, decreased social interaction and anxiety. The monkeys have also been able to pass the gene and their autism-like behaviors to their offspring.
The creation of the first genetically modified monkeys occurred in 2010 when the MECP2 genes were attached to a dormant virus injected into the eggs of crab-eating macaque monkeys. Once the eggs were fertilized, they were implanted into female monkeys in order to develop – and they did – 8 modified monkeys with 1 to 7 copies of the MECP2 gene. A year later scientists found that the monkeys were showing at least one behavior linked to autism. However, this was not enough to say that the monkeys involved in the study were autism models.
The next breakthrough came with the next generation of genetically modified monkeys. They started showing asocial behavior when they were 11 months old, which proved that the MECP2 gene and autism symptoms were passed onto the second generation of macaques.
Zilong Qiu, a molecular biologist at the Institute of Neuroscience, and his team are now using brain-imaging technology on the monkeys to identify exactly where in the brain the MECP2 over expression happens. They plan to use CRISPR gene editing technique to remove extra copies of the gene to see if autism-like behaviors and symptoms will cease.
For a long time, people have been using the traditional breeding techniques such as Artificial selection to obtain the desired characters in the various organisms ranging from ornamental flowers to milk giving animals. In this technique, the organisms having the desired traits are selected and bred to obtain the progeny having the desired qualities of both the parents. But, the problem with this technique is that we have no control over the characters or variations appearing in the progeny. However, with the advancement in the field of biotechnology and genetic engineering, it has become possible to control the characters in an organism right from the gene level. Today, a gene from an organism can be isolated and inserted into an organism of completely different species through the techniques of genetic engineering. The organism resulting from such mechanism is termed as Genetically Modified Organism or GMO.
Cloning and Recombinant DNA technology are the two methods which are widely employed for the development of the GMOs
In the process of cloning, a nucleus is isolated from the cell of the organism to be cloned and is introduced into an enucleated cytoplasm of the host egg cell. This egg cell is then further grown up to 16-32 celled stage and each cell is then transferred into different surrogate mothers. This results in the development of the progeny which is genetically identical to the donor. The first animal to be cloned using this technique was in the year 1996 where a sheep named Dolly was cloned from an adult donor cell. Since that time, a lot of animals have been cloned using this technique such as dogs, horses, cows etc.
In the recombinant DNA technology one or more genes responsible for the specific character are isolated from the organism showing that character, using the restriction enzymes and is then introduced in the host genome using the suitable ligating enzymes. The host cell is then checked for successful transformation and if transformation is successful, multiple clones of the cell are made. BT cotton, golden rice, humulin are some examples which employed this technology for their development.
These techniques have been very useful in the field of agriculture and medicine as they various drought resistant, pest resistant, high nutrition genetically modified crops have been developed. Also many drugs, hormones and enzymes of human use have been manufactured using genetically modified organisms.
Although these techniques are very useful, there are few drawbacks associated with them. Also, the long term effects of GMOs on the naturally occurring organisms haven’t been fully studied yet. Due to these causes the use of GMOs is still controversial and is under debate.
DNA sequencing means a process of determining the arrangement of adenine, guanine, cytosine and thymine in a DNA molecule.
In the mid-70s, a scientist called Fred Sanger developed a sequencing method called Sanger sequencing. This discovery of DNA code allowed more basic scientific applications to take place such as translational applications, diagnostic testing and drug therapy.
Many years of scientists improvements enabled Sanger to sequence sections of DNA up to approximately 600 bases in length. It was difficult to sequence one small section of DNA at once because of the more time and high cost required. Massively parallel sequences approaches, which are the Next Generation Sequencing (NGS) method enabled scientists to sequence hundreds of thousands of fragments of DNA at the same time.
“Next Generation Sequencing” (NGS) connotes various approaches use to sequence DNA.
- Smaller fragments for sequencing are derived from a sample of DNA.
- The NGS technology is used to read at the same time sequence of bases in many fragments of DNA. The fragments sequenced at the same vary from hundreds to millions and that depends on the type of sequencing taking place.
- The base sequences taken from DNA are generated in the form of a computer file. Each individual length generated from the original DNA fragment measures between 50-300 bases long, it is called, “read”.
- There is a specific program analyses the reads and matches specifically to the genome they arose from. This is what is called “alignment” or “mapping”.
- Variation between the sample DNA and the reference DNA are checked.
- Lastly the effect that a genetic variant will have on a protein is assessed. This is called “variant annotation”.
It is possible to sequence the whole of human genome quickly using these approaches. Many applications of NGS have been tried to find a specific genetic variant relevant to a specific disease but it has proved difficult. However, various methods have been devised which allow sequencing smaller regions of the genome. It allows sequencing just the portion of the genome that is likely to yield the relevant variation. This method is known as the “target enrichment” “capture” technique.
Over the past two decades, there has been a tremendous advancement in Gene Therapy. Since the first attempt of modifying human DNA in 1980 till now, several trials have been conducted while many are still underway to ensure that any gene therapy that is brought into the clinic is safe as well as effective. Some of the most successful advancements of Gene therapy for diseases are:
- Severe Combined Immune Deficiency (SCID):
This deadly genetic disorder known the SCID was one of the first genetic disorders to be treated successfully with gene therapy, proving that the approach could work.
- Chronic Granulomatus Disorder (CGD):
CGD is a genetic disease that affects the immunity of the patients. It is basically the disease in the immune system that takes away the patient’s ability to fight against microbial infections that can be dangerous. The Gene Therapy enabled the reconstitution of the immune systems providing protection against bacterial and fungal infections.
- Hereditary blindness:
Gene therapies are being developed to treat varied types of inherited blindness, especially the degenerative forms. The years long research shows that gene therapy has the potential to slow or even reverse vision loss.
Haemophilia is a disease where the blood does not clot and the patent suffer from continuous bleeding that can be fatal. This happens because the protein that helps the blood form clots is missing. In a small trial for the cure by gene therapy,the researchers successfully delivered a gene for Factor IX, the missing clotting protein, to liver cells.
There is a wide variety of cancers and thus, multiple gene therapy strategies have been evolved to cure them. Among the thousands of gene therapy trials, 2/3rds have been made to treat cancer and several of these are already in their advanced stages.
- Neurodegenerative Diseases:
There has been the recent advancement in Gene Therapy for the treatment of brain related diseases such as Parkinson’s and the Huntington’s disease. This is basically the loss of the cells in brain that produce the signalling molecule dopamine and the patient loses the ability to control movements. The Gene therapy allows introducing such genes into cells in a small area of brain and provides improved muscle control to the patients.
Zika virus has turned out to be deadly for almost all of South America. More than 2,500 babies have been diagnosed with it while there is a medical emergency being imposed. Many women are asked not to get pregnant or take immediate steps towards safety for better health. As the global health organizations work around a solution, which can help cure this epidemic, gene editing has some answers that can be applied.
In general, female Aedes aegypti mosquitos are the one that carry the disease, if gene editing techniques such as the Crispr-Cas9 can be applied in changing their sex, epidemics can be cured. Two US scientists have studied the potential. If successful, it may be used to cure malaria, dengue and other mosquito related infections and diseases which turn out to be deadly. Although in its initial tests, the experiments may need considerable time may be years to complete. The World Health Organization has already asked for bolder and innovative means to fight such diseases, specially Zika virus and Genetic modification can be one area that can bring in some insights. Another innovative idea is y using gene drive technology. It can help create anew generation of mosquitoes that carry malaria, which does not have the host plasmodium parasite that kills a child every minute in Africa.
Dr. Zach Adelman from the Virginia tech thinks this process of Crispr-Cas9 can help infuse a genetic modification in females, which can help turn them into having male characteristics. The gene drive technology can also be sued to kill female mosquitoes, hence reducing the overall risk of diseases. There were more than 214 million Malaria cases in Africa alone last year, such technologies and innovative breakthroughs have now become the necessity of time.
Recently, Gene editing has seen growth with the use of the well-renowned Crspr-cas9 therapy. It includes using genes to replace damaged cells in DNA, helping cure the diseases. After a lot of luck and hope, researchers are trying to use it on a more intense disease, which affects boys at birth. Duchenne Muscular Dystrophy is deadly, can let boys loose muscle really fast and putting them in a wheelchair by the age of 10, it can result in heart failure and death.
Although it has not yet been tested on humans, three researchers reported to the Science journal that they used the therapy on mice. They used a virus that helps infect the mice while attaching with the DNA to cure the dystrophin gene. The defective stretch of DNA that affects the gene is known as anexon. With exon removed or not present, mice were able to regain muscle strength while shortening dystrophin protein helped mice retain health faster. The team comprised of Amy J. Wagers from Harvard University, Eric N. Olson from Univerity of Texas and Charles A. Gersbach from Duke University.
The affected genes mostly comprise of 79 exons or sections, but can also function if there are fewer than these exons present. Unless the two ends are intact, the protein will keep on functioning. Dr. Oslon thinks in order to help this work on humans, more clinical trials are needed and may take a few years before the issues related to permissions in regards to gene editing is provided. It needs to be safe, right and be standardized for humans in order to avert any damages. Although patients may receive e a single dose of treatment, Dr. Gersbach thinks it may take several before the protein is eliminated and the DNA becomes resistant. As current chemical drugs are not helping cure this disease, gene editing is seen as the future to ensure the safety of affected patients.