BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: DNA (Page 1 of 4)

Our close cousins, Denisovans

Denisovans

Evolution is the change in the heritable characteristics of biological populations over successive generations. Evolutionary processes give increase biodiversity at every level of biological organization, including the levels of species, individual organisms, and molecules.

We once thought that the neanderthals were the only relatives but recent studies show that the Denisovans also interbred with humans.

This picture represents the spread of the Denisovans.

Modern humans are now the only human lineage left alive but others not only lived alongside modern humans, but also interbred with them, leaving behind DNA in the human genome. But with enough evidence, it has been proven that the mysterious Denisovans are relatives of modern humans. Denisovans also harbor a small amount of especially exotic DNA, probably from breeding with “super-archaic” humans that split from the others over 1 million years ago.

Previous research discovered that while Denisovans shared a common origin with Neanderthals, they were just as genetically distinct from Neanderthals as Neanderthals were from modern humans.

This diagram shows the spread of human.

According to researchers, ancestors of Oceanians interbred with a southern group of Denisovans, while the ancestors of East Asians mixed with a northern group.”The implication is that there were at least three instances of modern humans interbreeding with archaic humans — one with Neanderthals and two with Denisovans,” Browning said. “To me, this suggests that modern humans weren’t so very different from Neanderthals and Denisovans. There are signs that intermixing with archaic humans was occurring in Africa, but given the warmer climate, no one has yet found African archaic human fossils with sufficient DNA for sequencing,”

 

 

i-motif: A new form of DNA discovered

Australian researchers have discovered a new structure of DNA called i-motif. This form of DNA is in the shape of a twisted knot, vastly different from the conventional double helix model. i-motif basically looks like a four-stranded knot of DNA. In the i-motif form, the C bases on the same strand of DNA bind to each other instead of their complementary pairs.

File:G-quadruplex.gif

(Photo: Wikimedia Commons)

How did scientists discover i-motif?

i-motif previously haven’t been seen before, apart from in in-vitro (which means under laboratory conditions and not in the natural world) To detect i-motif, scientists used a tool made up of a fragment of an antibody molecule. This antibody could recognize and attach to i-motifs. Researchers showed that the i-motif structures mostly formed at the G1 phase -when mRNA is synthesized- in a cells life cycle. The i-motifs show up in promoter regions and in telomeres in the chromosome.

While scientists aren’t really sure the actual reason for their existence, some researchers suggest that they are there to help switch genes on and off and affect whether or not a gene is actively read.

Whatever the reason for their existence, they have potential to play an important role in how and when DNA is read. Prof Marcel Dinger at the Garvan Institute for Medical Research says, “It’s exciting to uncover a whole new form of DNA in cells — and these findings will set the stage for a whole new push to understand what this new DNA shape is really for, and whether it will impact on health and disease.”

The Genetic Secrets in Monkey Poop!

 

We’ve learned that two distinct species cannot produce viable hybrid offspring, BUT…

A researcher from Florida Atlantic University has documented that two genetically distinct species of guenon monkeys in Gombe National Park in Tanzania, Africa, have been successfully mating and producing hybrid offspring for hundreds or thousands of years! How did she learn this? From their poop!

Earlier Knowledge: Previous studies showed that guenon monkeys’ widely varying physical traits keep them from interbreeding because of mate choice. In other words, a male monkey won’t be attracted  to/mate with a female unless her face matches his. Therefore, blue monkeys and red-tailed monkeys (two different species) wouldn’t be expected to mate. The two species currently live in close proximity to each other in narrow riverine forests along Lake Tanganyika in Gombe National Park, and Kate Detwiler has been studying them for years.

 

Red-Tailed Monkey https://www.flickr.com/photos/derekbruff/13353495075

Blue Monkey https://commons.wikimedia.org/wiki/File:Blue_monkey_(Cercopithecus_mitis_stuhlmanni)_pair.jpg

 

 

 

 

 

 

The Breakthrough: Kate Detwiler, author and an assistant professor in the Department of Anthropology in FAU’s Dorothy F. Schmidt College of Arts and Letters, challenges this claim that red-tailed and blue monkeys don’t mate. She studies the extent and pattern of gene flow from “red tailed” (Cercopithecus ascanius) monkeys to “blue” monkeys (Cercopithecus mitis) due to hybridization. Detwiler observes and studies the two monkey species in Gombe National Park, and recognizes hybrids by combined markings of the two parent species. She estimates 15% of the population are hybrids!

The Evidence: Detwiler uses mitochondrion DNA extracted from the monkey species to show movement of genetic material from one guenon species to another. More specifically, she examined fecal samples and found that all of the monkeys (hybrids, blues, and red-tails) have red-tailed mitochondrial DNA traced back to female red-tailed monkeys. Using mitochondrial DNA was the best option because it is more abundant than nuclear DNA and only comes from the mother. In her study, her control group was a group of blue monkeys outside the park; when she extracted DNA from these monkeys, she found that they only had blue monkey DNA. Upon studying the hybrid monkeys, Detwiler found no consequences of cross breeding.

Detwiler’s Theory: The key finding made from Kate Detwiler’s study is that blue monkeys in Gombe National Park emerged out of the hybrid population. She speculates that red-tailed monkeys got to Gombe Natoinal Park first and thrived. Male blue monkeys had to leave their original homes outside the park and then mated with red-tailed females. How was the hybrid population sustained? Detwiler believes that the monkeys have learned socially that if you grow up in a hybrid group it is okay to mate with any other monkey.

So What? “The Gombe hybrid population is extremely valuable because it can be used as a model system to better understand what hybridization looks like and how genetic material moves between species,” said Detwiler. This is especially important because hybridization often occurs in response to environmental changes, and climate change is happening now! Who knows what hybrids we will see in the future? Check out the full article here to read more about this fascinating study!

 

 

 

 

A New Kind of DNA

Scientists at the Garvan Institute of Medical Research in Australia have discovered a new form of DNA in our cells. They’ve found that this DNA does not look the same as the traditional double-helix we are all familiar with, but instead is in the shape of a four stranded “knot”. This new DNA is called i-motif. Scientists not only know the shape of this new type of DNA, they also know how it differs from helical DNA and where it is located. Unlike helical DNA in which the Cs and Gs bind, the Cs on the same strand in the i-motif bind together.

Source: https://www.sciencedaily.com/releases/2018/04/180423135054.htm

In order to locate the i-motifs in the cells, researchers developed a new tool than can recognize this type of DNA. This tool is a fragment of an antibody that attaches to the i-motif DNA molecule. They used fluorescence techniques to find exactly where in the nucleus of human cells the i-motif DNA was.

Scientists also have concluded that the i-motifs most likely form at the late G1 phase. They appear in the telomere and promoter regions.

 

Crispr is coming soon to hospitals and medical facilities near you

In 2013, researchers demonstrated a type of gene editing ,called Crispr-Cas9, which could be used to edit living human cells. This means that DNA could be altered. It has been tested in labs, but now it is going to be tested on humans.
Crispr Therapeutics applied for permission from European regulators to test a code-named CTX001, in patients suffering from beta-thalassaemia, an inherited blood disease where the body does not produce enough healthy red blood cells. Patients with the most severe form of the illness would die without frequent transfusions.
If the trials are successful, Crispr, Editas and a third company, Intellia Therapeutics, plan to study the technique in humans with a bigger range of diseases including cancer, cystic fibrosis, hemophilia and Duchenne muscular dystrophy.

Since China is more lenient when it comes to human trials, several studies are already happened, but there was no conclusive data.
Katrine Bosley, chief executive of Editas, says the field of gene editing is moving at “lightning speed”, but that the technique will at first be limited to illnesses “where there are not other good options”.

The reason for this is because, as with any new technology, scientists and regulators are not fully aware of the safety risks involved. “We want it to be as safe as it can, but of course there is this newness,” says Ms Bosley.

Although Crispr-Cas9 has not yet been trialled in humans in Europe or the US, it has already benefited medical research greatly by speeding up laboratory work. It used to take scientists several years to create a genetically modified mouse for their experiments, but with Crispr-Cas9 “transgenic” mice can be produced in a few weeks.
Despite the sucesses, the field of gene editing has been hampered by several setbacks. Editas had hoped to start human trials earlier, but was forced to move the date back after it encountered manufacturing delays. Crispr has lost several key executives in recent months, while Cellectis had to suspend its first trial briefly last year after a patient died.

Crispr is in its beginning stages ,and although it is not yet mainstream, it is expected to be completely groundbreaking in the field of medicine.

Closer to Reality: Gene Editing Technology

In August of 2017, scientists in the United States were successful in genetically modifying human embryos, becoming the first to use CRISPR-cas9 to fix a disease causing DNA replication error in early stage human embryos. This latest test was the largest scale to take place and proved that scientists were able to correct a mutation that caused a genetic heart condition called hypertrophic cardiomyopathy.

CRISPR-cas9 is a genome editing tool that is faster and more economical than othe r DNA editing techniques. CRISPR-cas9 consists of two molecules, an enzyme called cas9 cuts strands of DNA so pieces of DNA can be inserted in specific areas. RNA called gRNA or guide RNA guide the cas9 enzyme to the locations where impacted regions will be edited.

(Source: Wikipedia Commons)

 

Further tests following the first large-scale embryo trial will attempt to solidify CRISPR’s track record and bring it closer to clinical trials. During the clinical trials, scientists would use humans- implanting the modified embryos in volunteers and tracking births and progress of the children.

Gene editing has not emerged without controversy. While many argue that this technology can be used to engineer the human race to create genetically enhanced future generations, it cannot be overlooked that CRISPR technology is fundamentally for helping to repair genetic defects before birth. While genetic discrimination and homogeneity are possible risks, the rewards from the eradication of many genetic disorders are too important to dismiss gene editing technology from existing.

 

Crispr-Cas9 is the gateway to a new frontier in genetic engineering. Here’s The good and the bad.

For a number of years now, molecular biologists have been diving increasingly further into the field of genome editing. The latest development into the field is the emergence of CRISPR-Cas9. CRISPR-Cas9 has risen to prominence over other potential methods of genome editing due to its relatively simple construction and low cost. CRISPR-Cas9’s original primary and intended purpose was to help fix mutations within DNA, and with this it could theoretically help eradicate entire diseases. This application of CRISPR is wholly positive, however with the increasing prevalence of the technique other potential uses have been discovered, and some of these potential uses raise profound ethical questions.

One of the main concerns of people skeptical about CRISPR is their assertion that once the door to the wholesale genetic editing of offspring is open, there is no going back. This, on its own, is a reasonable concern. The ability to choose a child’s sex, eye color, hair color and skin complexion is very likely to be made available to by CRISPR in the coming years. CRISPR does not yet have the capability to influence more abstract elements of the genome, such as intelligence and athletic ability, but this may not be far off. There are legitimate concerns that this is a slippery slope towards a dystopian society similar to the one seen in the movie Gattaca, where society is stratified into two distinct classes: those who are genetically engineered and those who are not.

Another concern raised by some scientists is the overall safety of genetic editing. A potentially very hazardous negative result of CRISPR is the possibility of an “off target mutation.” An off target mutation is the result of CRISPR mutating something other than the intended part of the genome and it could have disastrous consequences. Now, many scientists believe that with further advancements in the field the likelihood of something like an off target mutation occurring could be reduced to almost zero. However, it is important to examine the risks of any new process, and the prospect of something like an off target mutation occurring is certainly noteworthy.

For more information click here.

What does the future hold for CRISPR-Cas9?

Genome editing, or the technologies in which scientists can change the DNA of an organism, is on the rise, especially with its latest development, CRISPR-Cas9, the most efficient method of all of the methods to edit DNA.

Like many other discoveries in science, CRISPR-Cas9 was discovered through nature. Scientists learned that certain bacteria capture snippets of DNA from invading viruses, making DNA segments called CRISPR arrays, helping them remember the virus to prepare for future invasions of that virus. When they are confronted with that virus again, RNA segments from the CRISPR arrays are created which target the DNA of the virus, causing the enzyme Cas9 to cut the virus’ DNA apart, which would destroy the virus.

 

We use the same method in genome editing with CRISPR-Cas9 by creating RNA that binds to a specific sequence in a DNA strand and the Cas9, causing the Cas9 to cut the DNA at that specific sequence. Once this is done, the scientists create a sequence to replace the one that was cut to get the desired genome.

This technology is most prominently used to attempt to treat diseases, where the somatic cells’ genomes are altered which affect tissues, as well as prevent genetic diseases where the sperm or egg’s genome is changed. However, the latter causes some serious ethical concerns of whether we should use this technology to enhance human traits. But this begs the question that if we start using it more and more to prevent genetic diseases, will this open the door for it to be used in new ways?

CRISPR Cas9, too good to be true?

After its peak in popularity following its reveal as a possible “genetic modifier” in 2013, the CRISPR Cas-9 enzyme system has been the center of debate within the biology community. Thought to be the solution to all genetic and hereditary diseases by simply “cutting out” the fault gene, new research and studies have shown that a majority of people (65 to 79 percent) have antibodies that would fight cas-9 proteins.

“The study analyzed blood for antibodies to two bacteria from which Cas9 is derived: Streptococcus pyogenes and Staphylococcus aureus. The researchers’ concern stemmed from the fact that these bacteria frequently cause infections in humans, and so antibodies to them may be in our blood” states bigthink.com

While the overall effects are unclear, the study concludes that the result would be “significant toxicity” and an unsafe use of the gene editing tool.

What do you think? Is the current risk of using Cas-9 worth the reward?

Click here, here, and here for more information.

Cas9, photo by J LEVIN W

 

Potential cure to ALS, the disease that inspired the ice bucket challenge!

You all remember the ALS ice bucket challenge, that took social media by storm, in which people dumped ice water on their heads in order to raise money and awareness to ALS, a neurodegenerative disease that progressively destroys the motor neurons and eventually leads to death.

 

There is currently no cure to this horrible disease. However new genetic technology (CRISPR) may change all that.

In short, CRISPR is a new form of gene editing that allows scientists to change an organism’s DNA.

Scientists discovered that ALS is caused by a mutation in the C9orf72 gene. ALS is often caused by a significant repeat of a segment of DNA that becomes toxic. So, using CRISPR, scientists deducted which genes either protect against or cause these toxic DNA segments. This process was extremely effective and scientists found about 200 genes that affect ALS. For example, scientists found a gene that codes for a protein called Tmx2 that when removed from mice neurons caused the mice to survive whereas not removing them killed them. This means that scientists are beginning to figure out how to cure ALS.

Discoveries such as these are revolutionary as we can now find specific causes for previously fatal, cureless diseases  such as this. In addition, using this technology we can target these specific genes and save lives.

However, whenever we discuss gene editing we must ethically consider when does this become too far? Where is the line between helping to cure people and helping to destroy society by designing babies?

To answer my own question, I think it is crucial that we take any step possible to help find cures in situations such as this. That being said, there are clear limits that must be respected. The line is definitely hazy. Let me know in the comments your thoughts about gene editing!

But for now, let’s enjoy this scientific win and hope that ALS can be officially cured. Good job ice bucket challenge for bringing attention to a serious issue that may now actually be cured.

Original Article: https://www.sciencedaily.com/releases/2018/03/180305111517.htm

Cas9: A Clue Into Making Gene Editing Safer

CRISPR is a revolutionary system that edits the DNA of living organisms with ease. The gene-editing technology offers scientists insight into genetic diseases and is widely used in biotech and agriculture, as well as to treat cancer and viral infections. But the CRISPR system and its mechanisms are not yet fully understood. However, researchers at the Ohio State University have reported that they have figured out the mechanism of how the CRISPR system figures out where and when to cut the DNA strands. This is particularly revolutionary as it provides insight into preventing gene-cutting errors.

Cas9 is an enzyme that is used by the system to target and cut out or insert specific genes. In the second of two paper published in the Journal of the American Chemical Society, the team invalidates the widely-held belief that the enzyme cuts DNA evenly. Professor of chemistry and biochemistry Zucai Suo explains that instead of cutting both sides of the DNA double-helix to the same length, Cas9  actually trims each side to uneven lengths. Ohio State doctoral student Austin Raper and his co-authors determined that the two different parts of the “Cas9 molecule communicate with each other to set the location and timing of a cut”. The first part of the molecule sets forth to cut its respective DNA strand and changes shape and signals to the second part to cut its respective second strand.

Crystal Structure of Cas9 Enzyme

Suo says that he hopes their work allows for scientists to minimize and eventually eliminate gene-editing errors. CRISPR rarely target unintended genes, but gene-editing errors can have very serious consequences. For example, if the system accidentally cut a tumor suppressor gene from a person’s DNA, they would be much more likely to develop cancer. As Raper says, it is important to understand CRISPR and the Cas9 enzyme mechanisms in order to allow CRISPR to advance to its full potential.

 

Source: https://news.osu.edu/news/2018/02/28/cas9-2cuts/

Inside Out

CRISPR is a revolutionary tool used for editing the human genome. It allows for the altering of  any given DNA sequence and ability to modify any one specific genes’ function. Its applicability consists of correcting genetic defects, treating and preventing the spread of diseases, and improving crops. However, it also raises some ethical concerns, that of which mainly is the idea that practicing CRISPR technology could be considered as playing the role of “God”.

CRISPR was adapted from the natural defense mechanisms of bacteria, which use CRISPR-derived RNA and Cas proteins, to prevent attacks by viruses and other intruding organisms. They do so by chopping up and destroying the DNA of the virus. When these components are derived and applied to more complex, organisms, it allows for the manipulation of genes.

Disregarding its ethical concerns, CRISPR can provide substantial support to a previously uncharted area of medicine; the diagnosing and treating of genetic disorders, which was previously thought to be that if one had a genetic disorder it would be incurable.  Clinical trials are set to take place both in Europe and in North America, where patients with rare genetic disorders will give cellular samples in an attempt to alter their genome, implant them back into the individual, and hopefully cure the genetic abnormality.

With CRSPR taking such progressive strides in the past year, it is not outrageous to predict what its usage could end up providing society with.  With the ability to edit the human genome there are endless possibilities in which science could evolve this area of study to benefit the human race.  CRISPR can even be used to boost the expected intelligence of an embryo.  Who knows, thirty years from now we could be watching the news and hear of the first ever “superhuman”, a genetically modified human that has been hand-coded for optimality in all human functions.

The Future of CRISPR

CRISPR is starting to become more and more of a reality as Harvard professor David Liu continues to work on it. Liu was the person who originally developed CRISPR first base editor which allowed for single letter changes in the genetic code. Liu has come up with two new features to CRISPR-Cas9.

The first is called cellular detective or CAMERA(CRISPR-mediated analog multievent recording apparatus systems). What this function does is it finds the genetic problem that is responsible for the disease someone is experiencing. Cas9 will record all the cell data and piece info together, which overall will provide more information about cancer, stem cells, aging, and overall disease.

Photo Source

The second finding is referred to as sharp scissors which is a CRISPR enzyme. Sharp scissors are way more precise and accurate than the old enzyme making is much safer. The scissors depend on specific DNA to find the region where it is supposed to cut or edit. CRISPR is progressing and as more research is being done could be used on humans in the future.

 

CRISPR used to treat diabetes, kidney disease, muscular dystrophy

Scientists have now created a new method of using CRISPR genome editing, which would allow them to activate genetics without breaking the DNA. It could potentially be a major improvement in using gene editing techniques to treat human diseases. Currently, most of the CRISPR systems work by creating DSBs or Double strand Breaks in regions of the genome targeted for editing. Many scientists and researchers have opposed creating breaks in the DNA of living humans. So the Salk group tried their new method to treat diseases such as diabetes, kidney disease, and muscular dystrophy in the mouse models.

CRISPR has proved to be a powerful tool for gene therapy, but there are still many concerns regarding some mutations generated by the DSBs though the Salk group is able to get around that concern. Originally, Cas9 enzyme couples with guide RNA to create DSBs. But just recently, researchers have used a dead form of dcas9 to stop the cutting of DNA. DCas9 would couple with transcriptional activation domains, that turn on targeted genes. But it is still difficult to be used in clinical applications.

Salk group team combined dcas9 with bunch of activator switches to uncover a combination that would work even when the proteins are not fused with one another. These components all work together to influence endogenous genes. It would influence genetic activities without having to change the DNA sequence.

In order to prove the usefulness of this method, scientists used mouse models of acute kidney disease, type 1 diabetes, and a form of muscular dystrophy. They engineered their new CRISPR system to boost the expression of an endogenous gene that would reverse the symptoms of the disease. In all three cases, they reversed disease symptoms.

To understand more, click here.

 

Photo credit: Martyn Fletcher

 

CRISPR: Back at it Again

Researchers at the Gladstone Institutes made scientific history by turning skin cells of rats into stem cells by activating a certain gene in those cells using CRISPR technology. CRISPR technology is a tool used for editing genomes through making it easy for researchers to modify gene function and easily alter DNA sequences. CRISPR stands for “clusters of regularly interspaced short palindromic repeats” and it has been a popular topic of discussion and research in the science world.

Gladstone senior investigator, Sheng Ding and his team shaped their research aiming to answer the question; “can you reprogram a cell just by unlocking a specific location of the genome?” which they answered yes at the end. They decided to test on specific stem cells that can be turned into any cell type in the body, Pluripotent cells. Ding built upon a different senior investigators discovery, Shinya Yamanaka, who found he could make stem cells out of skin cells by treating skin cells with four key proteins called transcription factors. Here Yamanaka learned that the transcription factors could change which genes are expressed in the cell, turn off genes associated with skin cells, and turn on genes associated with stem cells and he called these skin turned to stem cells Induced Pluripotent Stem Cells (iPSC).

So Sheng Ding was inspired by Yamanaka’s investigation and decided to follow the same process but treat skin cells with CRISPR  instead of transcription factors. They targeted genes Sox2 and Oct4, only expressed in stem cells, which can turn on stem cell genes and turn off those associated with different cell types. With CRISPR, Ding and his team discovered they could reprogram cells activating Sox2 or Oct4. This proved to be more efficient than previous study, as using the CRISPR technology to target a specific location on the genome immediately triggered a natural chain reaction reprogramming the entire cell into an iPSC.

This was surprising and groundbreaking for this research group as they answered their guided question but came out with more. They still want to understand how the CRISPR technology was able to trigger a change within a whole cell efficiently and immediately compared to any other tested process. This study expanded knowledge on CRISPR and its many functions, and creates more questions on why and how it can do what it does. CRISPR technology continues to confuse scientists by manipulating genes in new, different, and unpredictable ways so the next question is, what does it have up its sleeve next???

Original Article 

CRISPR, A Cure to Heart Disease?

Photo Source page: Flickr.com

     While CRISPR‘s full potential in the department of gene editing is still being researched, scientists have just successfully discovered CRISPR’s ability to correct a defective gene that causes a certain type of heart disease. Though scientists are unclear as to the type of gene corrected in order to cause this change, this discovery was made for the first time in the United States, by an experiment done on live human embryos. However the new information yielded from this experiment is extremely beneficial as it shows CRISPR’s potential in correcting genetic errors that cause disease, as well as in human embryos meant for pregnancy.

Another reason for which this study particularly stands out in its importance, is because it is much different from the other developments scientists have made in CRISPR’s abilities. Studies have been conducted worldwide using CRISPR to edit of somatic cell’s gnomes, however, this only affects individual people. This study (also done by researchers in China), has been done by editing germ line cells, which result in changes that are passed down through every following generation.

However since the changes made to cells do affect all generations that follow, scientists are unsure of the exact effects of this new technique. Although it seems that this technology will be very beneficial in stopping harmful genetic diseases, it can also be used for changing DNA to genetically determine the eye colors, height or even mental and physical abilities and intelligence. This new phenomenon is own as “designer babies”, and for many reasons, this is not something that the United States is trying to use CRISPR’s abilities for. For this reason, United States has recently created more severe guidelines regarding gene editing technology, as well as enforcing CRISPR’s use on embryos only for prevention of harmful genetic diseases, when other treatments were not successful – as a last resort – formed by the National Academies of Sciences, Engineering and Medicine.

In the study done, scientists edited out a mutant copy of MYBPC3, using CRISPR. MYBPC3 is a gene that encodes a protein that creates well maintained and structured heart muscles. Hypertrophic cardiomyopathy, known as HCM, are caused by mutations in that gene, and cause spontaneous cardiac arrest. This occurs in even the youngest and healthiest of athletes, affecting 1 in 500 humans.

In this study, the mother was carrying the normal version of a gene, while the father had the mutant gene. Using CRISPR, the scientists were able fix the mutant version, by cutting and replacing the DNA. Directly after they placed the fertilized egg in a petri dish, while introducing the genome editing parts at the same time. The results of this process proved to be very effective, as 75% of the embryos showed no mutant genome. Without the use of CRISPR when egg fertilization occurred, the chances of mutation would have been present in 50%!

From these results the researchers came to the conclusion that they have realized the potential for mosaicism. Mosaicism is when only some of the cells are edited and the rest are not affected, which results in some normal cells, as well as some mutant cells. The scientists have also gathered the effects of off-targets. Off targets are the CRISPR edited genes that appear to look like mutant genes, but are actually not. Within this study, one egg fertilized from 58 showed mosaicism, and there was no detection of effects from off-targets. Theseare very impressive results, due to the fact that both of these possible situations can cause limitations in effectiveness and safety.

Though researchers need to do over this experiment many times in order to soliditfy the effectiveness of this study for the future, if they want to use this on eggs intended for pregnancy, as the eggs fertilized in the study were not meant for pregnancy… However, the results have yielded nothing but good news for the future of CRISPR technology (besides, the risk in advancements in “designer babies”, which couldchange the future of conceiving, forever…). This article was extremely interesting for me to read, as I am very interested in studying Biology in the future, or even pursuing a track to medicine. Perhaps, I may get the chance to even experiment with CRISPR at some time in my life, as it becomes a growing presence throughout the science world!

Primary Source Article: U.S. researchershave used gene editing to combat heart disease in human embryos

CRISP New Technology: CRISPR

If you have ever seen GATTACA, and thought ‘Wow! I want to edit my genes!’… you may be in luck! CRISPR technology is a simple tool for editing ones genomes. (CRISPR is just a nickname for “CRISPR-Cas9”. ) A genome is an organism’s complete set of genes, including non-coding nucleic acid sequences. CRISPR technology has many different applications, including altering DNA sequences, modifying gene function, correcting genetic defects, and preventing the spread of diseases. Although all of these functions sound positive, CRISPR technology seems to raise ethical concerns.

 

DNA Pencil: Edit Photo By: mcmurryjulie

CRISPR stands for “clusters of regularly interspaced short palindromic repeats”, and is a specialized region of DNA with two definitive characteristics: the presence of nucleotide repeats and spacers. Nucleotides are the building blocks of DNA, and eventually proteins. CRISPR technology was adapted from the natural defensive mechanisms of bacteria. In order to repel attacks, these organisms use CRISPR derived RNA and various Cas proteins (including Cas 9), to attack foreign viruses, or other unknown bodies. CRISPRs are specialized stretches of DNA. The protein Cas9 is an enzyme that acts like a pair of “molecular scissors” which acts to cut strands of a person’s DNA. This protein usually binds to two RNA molecules: cRNA and another called tracrRNA. These two forms of RNA guide Cas9 to the target site, where it will make it’s “cut”. Cas9 cuts both strands of the DNA double helix, making what is known as a “double strand break”. This is how genes are editing.

Bouncing back to the defensive bacteria organisms that started this all, they attack foreign invaders by chopping up, and therefore destroying, the DNA. This allows for the manipulation of genes. These bacteria also use the spacers as a bank of memories which allows the bacteria to recognize viruses and other invaders.

However, due to these discoveries of how CRISPR technology works in bacteria, CRISPR technology is now going to be used to edit the genes of people to change genomes and possible diseases and phenotypes. This has caused some ethical concerns to arise in regards to CRISPR technology being used for human genome editing. Most of the changed involving genome editing are limited to somatic, or body cells, (not sperm or egg cells). Changes in body cells can’t be passed from generation to generation, but changes in sex cells can be passed onto future generations. Some of the previously mentioned ethical concerns include whether it would be a good idea to use this technology to enhance normal human traits (including height and intelligence). Due to these ethical concerns these genome edits are actually illegal in many countries!

Could CRISPR Cure Duchenne Muscular Dystrophy?

What is Duchenne Muscular Dystrophy?

https://www.flickr.com/photos/150276478@N03/34406844136

Duchenne muscular dystrophy, DMD, is an X-linked recessive disease caused by defects in the gene that makes the dystrophin protein. This particular gene is made of 79 exons, and the defects can occur on any of them. These defects lead to degeneration of skeletal and heart muscle, forcing patients to rely and wheelchairs and respirators. Without a cure, most people with the disease die by the age of 30. So, the question becomes, how can we find a cure?

What is Precision Editing?

http://www.njsta.org/news/crispr-in-the-classroom-by-simon-levien

CRISPR technology has advanced tremendously in the past several years, with each study building off the last. CRISPR technology has the capability to cut out segments of DNA, but with the risk of cutting out too much or the wrong parts. Thus, it is crucial that the cutting be as precise as possible. The CRISPR-Cas9 gene-editing tool, uses an RNA strand to guide the Cas9 enzyme along the DNA strand, skipping over important “healthy” DNA and leading the enzyme to cut a specific portion of DNA.

 How do DMD and Precision Editing Connect?

Dr. Olsen is Co-Director of the Wellstone Muscular Dystrophy Cooperative Research Center, a lab in which a team has been working to apply precision editing to DMD. The method uses one single cut of DNA along strategic points and is less intrusive than other methods. Scientists have developed guide RNAs with the purpose of finding mutation “hotspots” along the dystrophin gene. The RNA strand guides the Cas9 enzyme to 12 regions where most DMD mutations have been found. According to the article, “the new strategy can potentially correct a majority of the 3,000 types of mutations that cause DMD.” Wow! In a recent study using this method, these RNAs helped rescue cardiac function to near-normal levels in human heart muscle tissue.

Why is it Important?  

The new study demonstrates eliminating abnormal splice sites in human DNA can correct a wide range of mutation. In the case of DMD, the splice sites that were removed using CRISPR technology instruct the genetic machinery to build abnormal dystrophin molecules. Once these sites are removed, an improved dystrophin protein was observed. Even more fascinating, correcting only half of the damaged cells restored cardiac function to a healthy level. Does this sound fascinating? If you answered yes, click here to learn more!

What Does the Future Hold?

The strategy of single-cut editing may be useful for treating other single-gene diseases. News of such prospects has generated a great deal of hope for patients. Much more research is needed before CRISPRCas9 can be used on human patients. Labs and researchers around the world are working to perfect this method so that it can get federal government approval and move to the next stage – human trials. As research progresses, it will be faced with backlash from some who believe DNA should not be altered and that the technique is too risky and support from those who believe this new technique could save lives. Which side do you fall on?

Gosh…You’re Such a Caveperson!

Do you know your ancestry?  While all humans beings have their own varying histories, many are held together by one ancestral truth. They are all partly Neanderthals!  A new Neanderthal woman has been found in Croatia, and the tests being performed on her are changing the way scientists perceive human genealogy.

This discovery may be more impactful news for humans that originated outside of Africa.  For those who migrated out of Africa, scientists have cause to believe that Neanderthal DNA accounts for 1.8 to 2.6 percent of their DNA!  Considering that the common belief had been that Neanderthals accounted for 1.5 to 2.1 percent, this new knowledge is a great leap forward in understanding the way that evolution and ancestry shape the life of the modern human.  The genes that Neanderthals contributed to the modern human may affect cholesterol, mental health, body fat levels, and more.  Don’t be too alarmed about the potential negative side effects of sharing Neanderthal DNA, though.  The lead author on the study, Kay Prüfer, clarified that Neanderthal DNA is not definitively bad for your health.  He said, “We find one variant that is associated with LDL cholesterol, and the variant we got from Neanderthals is associated with lower LDL cholesterol.” So, rest assured.  Neanderthal DNA does not mean you will have certain health issues. It only means that you can.

These studies are not only teaching scientists about humans, though.  By comparing the bone fragments of the Neanderthal found in Croatia with another Neanderthal found in Siberia, scientists discovered that Neanderthals are extremely similar in DNA to one another.  Despite being from different parts of the world, both Neanderthals had strikingly close DNA structure.  This closeness in DNA is most likely a cause of a small population.  All of this information sheds a light on the low density of the Neanderthal population as well as their way of living.

While this discovery has greatly reshaped the way that we view modern human DNA, research on Neanderthals persists. Scientists hope to find even more information that will teach people about the history of Neanderthals as well as their influence on the human race.

 

How DNA damaged from radiation causes cancer

In a recent study, professors from the Wellcome Trust Sanger Institute sought to see the similarity between spontaneous cancerous tumors and cancer caused by ionized radiation. By looking at the molecular fingerprint of different types of cancers, they were able to differentiate between cancers that formed by radiation and cancers that were not formed by radiation.

In the study, they studied the mutational signatures of the DNA. Mutational signatures are just ways in which the DNA is affected by cancerous mutations. They studied the DNA mutational signatures from DNA exposed to radiation, but not necessarily cancerous, and the mutational signatures of the DNA of cancerous cells of which some were caused by radiation exposure and some were not. Both included the same signatures.

The two mutational signatures that were observed were deletion of segments of DNA bases and balanced inversion, where the DNA is cut in two places, the middle piece flips around, and the pieces are joined back in the opposite orientation from before the flip. High energy radiation is the cause for balanced inversion, since it does not happen naturally in the body. After the mutation, the DNA cannot repair itself.

This gives us a better understanding of cancer and how ionized radiation affects DNA and produces these mutational signatures. Knowing this information, this helps us recognize which tumors are caused by radiation. Once we have a better understanding of this, it will prove important for determining how each cancer should be treated. But for now, this is a strong step forward in the battle against cancer and every step of the way is crucial if we are to be victorious.

 

Page 1 of 4

Powered by WordPress & Theme by Anders Norén

Skip to toolbar