Do Identical Twins Have Identical DNA?

 

Although identical twins may look pretty similar, at the DNA level, they are not. Identical twins tend to differ by 5.2 genetic changes researchers have suggested in an article. Monozygotic twins, also referred to as identical twins, come from a single fertilized egg and are often studied to determine if particular traits, diseases, or even conditions can result from genetics or environmental influences. For many decades people often thought that identical twins were genetically the same because they are so similar; therefore, differences in their health were considered to be the result of their surrounding environment. But new research has suggested otherwise and that these genetic changes could also account for differences between twins. Researchers in Iceland have interpreted the complete genetic makeup of 381 pairs of identical twins. For 38 pairs, they were genetic duplicates of each other, but differences in DNA were shown that most likely arose in early development. For 39 pairs, there were many differences between twins' DNA, with some having more than 100 changes between them. The patterns of mutations seen by researchers within the genetic DNA of twins suggest that the embryos do not split neatly when twins form. Some twins may arise when a single cell or even a small group of cells split off from the embryo. The number of cells a twin originates from determines how genetically different they are from their twin. If there are more uneven splits of the embryo, that tends to lead to increased differences between twins.

To me, this article was fascinating to learn about and to know that at such an early stage in life a little change in genetic mutations can differ a whole sequence of someone's genetic makeup. I have always thought that identical twins were identical in their genetic make, therefore that is why they look so similar. It's amazing to be see what we can learn by genetic research. 

Ethical Debate Surrounding the Protection of "CRISPR babies"

There are discussions in China’s bioethics community to set up a research center to ensure the well being of the first children born with edited genomes. He Jianki announced that he had created babies with altered genomes in 2018, and these discussions began following the possibility of his release from prison. In the latest proposal, researchers have said that these children would need special protection as they are a “vulnerable group”. Gene editing could create errors in their genome which could potentially be passed to their children, and their genome should be sequenced regularly just to ensure that there aren’t any abnormalities. Because there are no updates on the children’s current condition, it’s difficult to make recommendations. 

He implanted embryos in which he used CRISPR-Cas9 to edit CCR5 in an effort to make them resistant to HIV. As a result of this, twins were born in 2018. The parents agreed to this because of the fact that the father was HIV positive. In 2019 He was sentenced to 3 years in prison. The children are toddlers now, and are the only children with an edited genome. Despite promising that these children would have medical insurance, they were born prematurely which interfered with that promise and were initially denied medical insurance. He stepped in to pay.

This article brings up the issue of excessive surveillance. While these children are vulnerable, there are also social and psychological risks to be accounted for in the recommendations on how to properly protect them. These children would have to endure medical testing regularly throughout their life, which could have an effect on their mental health and a variety of other components of their lives. It is interesting to see the ethical side to certain medical situations, as the editing of their genome could have a long term effect on their psychological health.

All identical twins may share a common set of chemical markers on their DNA

Identical twins share many things, including DNA but new research suggest there is a signature of the twinhood. Part of the  epigenome, which are chemical markers that influence genes without altering sequence. These signatures could be used to identify a twin who might have lost their sibling in the womb or separated at birth. It is known that monozygotic twins form from the same zygote splitting into two embryos during development, but it is not clear why it happens is unclear. Scientists begin to look at the epigenetic differences along 450,000 sites of the genome of roughly around 6,000 monozygotic twins and dizygotic. 834 sites in identical twins were highly similar, from young to old twins, and from geographically different locations. These markers were very common among the twins that as of now, there is an 80% accuracy of identifying a twin who might have lost their sibling without even knowing that were a twin.

Embryos appear to reverse their biological clock early in development

 

Aging does not carry over to the next generation of progeny. There is no inheritance of the age of your parents and the germ-line cells are responsible. Once thought to be ageless or immortal but found to be untrue, the germ-line cells now are thought to possess a function that acts as a reset on their age. In a new study, scientists report that both mouse and human germ-line cells reset their age early in embryo development. The biological clock of a mouse embryo being studied was constant and unchanging but after 6 to 8 days, the age had taken a dip. The understanding of this process and the ability to control it could lead to further advances on battling age-related diseases like arthritis or Parkinson's. It is still unknown what the mechanism behind the age changes in these early developmental cells and further research will be necessary to uncover it.

Mouse Embryo Grown in a Glass Womb

Mammals develop in the uterus of its mother, forming from one cell into trillions. Researchers have found a new method to observe the development of mice embryos without have to cut open the mother's womb. A "glass embryo" was created by using a beaker filled with a nutrient rich solution, an environment identical to a female mouse's uterus. The embryo survived for 11 out of the usual 20 days it takes for the embryo to fully develop. 

Although the pup did not survive the entire time, researchers were able to observe the development of multiple systems. This could lead the way to observing development in other organisms. The new method is pretty special and it must be amazing to see the development of a lab-grown embryo. 

Websites:

https://www.the-scientist.com/news-opinion/lab-grown-mouse-embryos-form-limbs-and-organs-68565

https://www.nytimes.com/2021/03/17/health/mice-artificial-uterus.html 

Designer Babies

Genetically modifying embryos to have certain desired traits is far from being done. The ability to select different traits is much more difficult than targeting genetic diseases. This is because genetic diseases can be caused by a single mutation, while selecting certain traits is influenced by multiple genes. Shai Carmi said how it is much more accepted to alter a baby if it is for a disease versus an outward identity. Also traits can be very unpredictable, even if altered.

In my opinion, I do not think genetically modifying embryos should be allowed with the purpose of a "designer baby." I think it is acceptable to modify in the interest of the health and well being of a child, but to completely change their characteristics should not be okay. If somebody wants to change the way they are, it should be decided by them, not their parents. Also all life should be accepted the way it is, parents should be happy with the way their baby looks without genetically modifying them. I hope this is never something that is available to the public when it does become successful.



https://www.usnews.com/news/health-news/articles/2019-11-21/designer-babies-a-long-way-off

Related Article:
https://embryo.asu.edu/pages/ethics-designer-babies

Who's a good... Wolf?

The loyal dog's we know today, are relatives to the wolf. They are our trusty companions but why? Where did the floppy eared, big eyed, goof we know today come from (yes there are dogs that are bread to have ears sticking up as well)? Evidence points to dogs being our longest and oldest companions being domesticated not only from a single area but from multiple points all around the world.

Many have hypothesized how wolfs ended up becoming domesticated. Some believe that we actively tried to domesticate them to be used for hunting, helping our ancestors and acted on their own accord. Others believe that the wolf  (some) began to follow our trail of scraps left behind in search of food themselves and that they had a trait in their genome that was more tame that would allow for us to allow for them to approach us.

From studies done we know that the Eurasian grey wolves around 10,000 to 40,000 years ago were domesticated. Dogs that we know of today like the Doberman, Maltese, Pitbull, Pomeranian, and ect. were not what the early traits were sought out for physical aesthetics but rather only that they do not hurt us and are friendly. It should be known that the traits for behavior and physical attributes are linked in a way. They are the NCC or neural crest cells, and biologist have focus in on these as they believe this is what was the catalyst for the domestication syndrome.

"NCCs are stem cells found in every embryo that show up first at the crest, or top edge, of the neural tube, which will eventually become the brain and spinal cord. As the embryo develops, a number of different genes signal NCCs to activate and move, along specific paths, to different areas of the body to perform different tasks. the range of activities that NCCs do it enormous: the adrenal and pituitary systems, which are involved in aggression, fear and other behaviors, are derived from NCCs, but these cells are also involved in regulating physical traits such as pigmentation of skin and hair."(1)

The group of scientists involved in this study decided to look into 429 different genes in forty three wild village dogs from four different continents. Focusing on genes that act in early embryogenesis. They then compared these village dogs to "ancient dogs older than 5,000 years" (1). What they found was a similarity in their genome sugesting that these traits were the result of original domestication. This shows that the later attempts of domestication to different specific breads was not the cause for the tame like trait we see in dogs. 

"Selecting for behavioral traits such as reduced fear of humans, a key element of tameness, favored certain genetic signatures. In turn, those genetic signatures changed how the NCCs they activated actually migrated around the body and performed."(1)

Even with this new information we do not know how domestication took place but we do have more insight into it. We may never know why or how specifically this domestication of our fury friends happened, but what we do know is that they were part of our journey so far and are not going anywhere in the near future. The dogs we know of today will continue to change in features as we deem to be necessary/aesthetically pleasing.

P.s DO NOT try to domesticate wild wolves.

references:
1- http://blogs.discovermagazine.com/d-brief/2018/06/27/dog-genes/#.W2ELUtJKhPY
2- https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-018-0535-2

Rhino Embryos Made in Lab to Save Nearly Extinct Subspecies

The number of northern white rhinoceros have dropped substantially to the single digits over the past decade. The few that remain all have severe reproductive issues. Hopes of regenerating the subspecies only became worse when Sudan, the last male northern white rhino, died in captivity last spring. “We thought, ‘The story’s over’,” stated Dr. Thomas Hildebrandt. However, it soon became far from over as Dr. Hildebrandt and his colleagues created hybrid embryos that can possibly be implanted into female surrogate southern white rhinos. The expectation is to see the first purebred northern white rhinos through this method in the next three years or so. However, a major downside is the likelihood of severe inbreeding in order to produce purebreds. This could cause reproductive issues for the hybrid subspecies and lead right back to square one.

Although I applaud the technical sophistication and advantages that have been made throughout this study, it is also concerning that too much technology might do more harm than good. Nonetheless, if this experiment proves to be a success, it could lead to the survival of other extinct subspecies.

Article link

Related article

U.S edits Embryo DNA for first time

 

     Without a doubt, I found this article very interesting. Scientist have successfully edited embryos so that they could grow and develop if placed into a mother's womb. This is the first time this is happening in the U.S. The gene altering technology is referred to as CRISPR. By injecting CRISPR into the embryo about the same time that is it getting fertilized by the sperm it reduces the risk of "off target editing"(Newman). This is extremely valuable in the world of medicine. It will help correct genes that are dangerous to future generations. They could also eventually alter inherited diseases to help those. Although these are all positive factors, I do believe this technology should be evaluated to fit culture appropriation.
    Personally, I think its great to see technology improving, specifically in genetics. When thinking of this article the idea of "Designer babies" popped in my head. People may want to pay to have their embryos genes altered making the baby ideal phenotypically. Many will argue that this is morally wrong and should only be used for medical needs.  I think it may become a main focus causing a nationwide debate when the technology improves more.

Article: https://www.usnews.com/news/national-news/articles/2017-07-27/scientists-edit-the-dna-of-embryos-for-first-time-in-united-states

Gene Editing

There has been much talk over the years over whether science would evolve so people would be able to artificially select for certain characteristics or even be able to select against certain deliberating diseases. Scientists are on the way to making this happen. This new technique called Crisper's has revolutionized the ability to edit DNA. Although there is not much being said in this area due to ethical concerns and issues, scientists have reported that they have successfully edited harmful mutations out of human embryos. This new advanced technique is facilitated by a system called Crispr-Cas9, which has enabled the ability to snip, insert, delete, and edit genetic material with unprecedented precision and ease.

Article 

Breakthrough in Science Finds a Way to Edit Mutations in Human Embryos

 

For the first time in science, scientists have found a way to edit genes to prevent a dangerous disease causing mutation to be able to produce healthy embryos. This new research marks a huge milestone because it raises the prospect that gene editing may one day be able to protect babies from a variety of hereditary conditions. Consequently, this new research has also raised some cultural implications; a major one being that people with money may be able to artificially design progeny with certain traits, like greater intelligence or athleticism. Scientists are working to urge people to only use this new genetic engineering for individuals with dire medical problems to prevent cultural implications. Some highlights of this new gene editing is that it is now declared safe and that embryos repaired of a genetic mutation will develop into healthy babies and not be able to pass the disease onto their offspring.

Article 

First US Success of Nonhuman Primate Gene Editing

CRISPR has allowed scientists to move forward with great advances in gene editing in various species other than the commonly used mice. Such is the case of a study led by Michigan State University who have shown the effectiveness of gene editing in Rhesus monkey embryos using CRISPR/Cas9 technology. This is the first time this has been demonstrated in the U.S. This work is so important because mice are the usual model but they are not as ideal because their anatomy and physiology are so different from ours. However, a monkey would react more similarly to humans in regards to improved health and symptoms. Nonhuman primates are perfect models for diseases such as dementia, Alzheimer's or autism and would be favorable for looking at outcomes of surgical procedures, and implants. A big problem presented by the study is the cost of raising nonhuman primates because it can cost around $15,000 which of course is an enormous difference compared to rats. Nonetheless, the high-efficiency of gene editing they are now able to preform makes it worth it. I think this is a great step forward for gene editing and it's efficiency but I try not think about what is done to the monkey's for these scientific advances.

https://www.neb.com/tools-and-resources/feature-articles/crispr-cas9-and-targeted-genome-editing-a-new-era-in-molecular-biology  : For more information on CRISPR/Cas9 and genome editing.

https://www.sciencedaily.com/releases/2017/05/170501112525.htm :Article

Three Person Embryo's

This seems very interesting, and it's a great way for mothers to be able to carry their own healthy child, and not have to rely on a surrogate or an adoption to have a healthy baby. It still seems a little confusing to me, but I think this would be an amazing thing for mothers who are worried about passing on bad genes, since it says mostly every embryo the mother passes would have those mutated genes. The child would still have the looks but wouldn't have the mutations of the mother.

This article was from a few years ago, but this one is just from last month, their latest update.

HIV Resistant Embryos

There is a new evolution in human genetics - researchers in China have successfully edited the genes of a human embryo to be resistant to HIV infections. They did this by modifying a gene that is known to be linked to a blood disease. This is only the second time that gene editing in humans has been published.

To make the embryos resistant to HIV infection, researchers had to introduce a mutation that shut down the gene CCR5. This mutation is found in some humans, which explains why they are resistant to HIV. This mutation does not allow the infection to enter blood cells, preventing HIV. The scientists were among the first to introduce this mutation by using a system called CRISPR. Some scientists argue that this experiment just made headway with this way of manipulating cells, they did not make any significant scientific findings in working with human embryos.
There are still others that argue that there are things wrong with the way the experiment was conducted. The research was done on human embryos. Although they were embryos with extra chromosomes, making them not viable, there is still a question about ethics. Some scientists wonder if this experiment was necessary. While others wonder where this information can lead us to. There are a few that see nothing wrong with the experiments with embryos.
With this research on the table, there is no saying where embryo experiments can start, what types of eggs they use, and when they end. Will it get to the point that scientists can create a genetically modified human? Only time, and evolution of laws and ethics, can tell.

Red-Eye Tree Frog Embryos Escape Danger

A trait unique to this species, red-eyed tree frog embryos can hatch in an instant to escape dangerous predators. In an article by Live Science, this frog can be seen hatching as early as four days into development. Typically, undisturbed embryos can hatch after six or seven days. An embryo can identify vibrations from their surroundings, attributing them to rain, predators, or other things in their surroundings. If it was a predator they sensed, they quickly use their unique survival trait to escape. 

While most frog embryos release an enzyme throughout development that weaken the egg membrane over time, the red-eyed tree frog is able to store this enzyme in their snouts. The embryo will quickly release it onto the piece of egg membrane directly in front of them to create a weak spot in the egg from which they can hatch and make their escape. This method allows the embryo to make a quick getaway in as little as 6 seconds. In an article by the New York Times, Dr. Warkentin explained that she did not know of any other frog with such a short speed of hatching.

An extraordinary behavior first identified in 2005, this recent discovery explains the genetics and mechanics behind the process, and is truly amazing to behold. I believe that this trait, totally unique to the red-eyed tree frog, is a trait most organisms in the animal kingdom could greatly benefit from. To be able to have control over your own birth date like that, and to be able to save your own life before it has even started is very gratifying.

Saving The White Rhino

The White Rhinoceros is in immediate danger of going extinct.  There are only three individuals of this species left on the planet.  In an attempt to try and keep the white rhino from disappearing, scientists are working together and using cellular techniques to save them.  Of the existing rhinos, they are no longer able to breed naturally.   What these experts are doing is basically creating lab-grown embryos from frozen genetic tissue and harvesting them into surrogate mothers.  An issue could arise while trying to get the embryo harvested; considering no one has ever done it before and the rhino is said to have a highly convoluted and impenetrable cervix.

Some people are against this and think that more money should be used to prevent poachers from driving the animals to extinction.  That's a good idea, except this could lead to other possibilities of saving endangered species where preventing poachers isn't an issue.  Some people fail to take into account that they are driving other species to extinction, assuming they all have very large carbon footprints.  I personally am very excited to hear how this experiment goes.  It would be incredible to know they have the ability to save a species from extinction and also making advances in reproductive technology. So many other advances in science will be made possible if this works smoothly! 

Male Sensitivity Written in the Genes

In a study, it was found that the gene responsible for activating male development is surprisingly unstable, leaving inconsistencies in the pathway to male sexuality. Normally, in human development certain genes act as master switches that ensure we are born with similar attributes such as one hand, two lungs and 10 fingers. These genes tend to highly reliable and resistant against environmental factors. However, the SRY gene on the Y chromosome has the job to set off the growth of male sex organs in human embryos but if this gene is unstable and fails to fire, it can leave a genetically male embryo to develop as a sterile female. Researchers found that the SRY is highly vulnerable, allowing any interruption to alter male sexual development, which would ultimately lead to a variety of testosterone related male attributes.

I liked this article because I’ve heard of these cases in the past where the female inherits male attributes as an embryo. To realize that it’s the SRY gene that causes this defect is interesting especially because they say it’s very sensitive to environmental factors. It would be nice to see if they would research what exactly these factors are to help prevent this defect from reoccurring in the future.

Pair of Genes Responsible for Wing-Shaped Fin Development in Batoids

Researchers at the University of Chicago have identified a pair of genes responsible for the wing shaped fins of skates and rays.  Rays, skates and other batoids have some of the most unique fin shapes of all aquatic species.  In an attempt to further understand how limbs in all animals develop researchers at the university of Chicago investigated the genetic and molecular cause of the unique shape of fins found in batoids.  The team accomplished this by studying gene expression in the embryos of batoids. In the developing limb, there are genes and growth factors arranged in a specific order which help to create the apical ectodermal ridge (AER).  The AER is a region that stimulates cell proliferation along the growing edge of the limb which is responsible for elongation and proper development.  They discovered that early in development batoids mirror limb development of other fish and tetrapod species. However unlike other fish and tetrapods which only have one AER, the batoids posses a second AER.  The presence of this second AER allows for development of the pectoral fin towards the tail and the head of the ray.

The researchers also found that different groups of genes control the two different regions of the fin.  The 5' Hox family of transcription factors and the Fgf10 growth factor are commonly found among fish species was also found and active in the batoids, this group of genes was responsible for growth towards the tail.  The region growing towards the head was controlled by 3' Hox transcription factors and the Fgf7 growth factor.  In species other than the batoids, the 3' Hox and Fgf7 are found at the base of the growing limb, the presence of these genes in the anterior portion of the growing pectoral fin of batoids suggests that this is a unique adaptation of the batoid species and is responsible for the second AER, giving them their fin shape.

Interestingly, although the two regions of the rays fin are nearly identically the gene expression in these regions is totally different.  This group of species have different mechanisms that control fin development compared to other fish species giving them their unique fin shape.

Human Development Influenced by Ancient Viral Molecules

Researchers have found that certain viral molecules that have been left over from millions of years of evolution play a huge role in human' development. These left over viral molecules are essential for an embryo to differentiate into all the tissue that is present in a humans body. When they blocked the production of the RNA molecule that was responsible for this differentiation, they observed that all development abruptly stopped. They hypothesize that this viral RNA sequence infected humans long ago. Instead of being detrimental it was incorporated into their genome to serve a useful purpose. 

This new data is very useful to help us understand how we evolved certain traits that differ from some of our closely related species. Using this information can give us a clue about the origins of certain species and also show the role that viruses and bacteria played in the formation of our current genome. 

An artists rendering of a virus.

 

Chinese Scientists Utilize CRISPR- Cas9 on a Variety of Animals

Scientists in China are utilizing a new gene altering technique CRISPR-Cas9 to genetically modify organisms.  This technique uses enzymes to locate and snip out segments of DNA to isolate or inhibit a trait.  According to Scientific America, this DNA editing technique is much cheaper, faster, and more successful than other DNA editing techniques. There is a wide- application for this technique ranging from genetically altering animals for consumption, designing pets that have desirable traits to the owner, altering animals for scientific research to name a few.   One way this new gene editing technique is being used is to selectivity delete the genes that suppress hair and muscle growth in Shaanbei cashmere goats.  These goats are breed for their wool for textiles and meat as a source of food.  The impact of this new and successful DNA editing tool extends outside of the world of agriculture and has application in biomedical research.  A different group of Chinese scientists are implementing the use of CRISPR to engineer monkeys that posses neurological diseases, then using those models to study the effects of various neurological diseases.

This is an amazing accomplishment for the international scientific community, increasing the reliability and speed with which genes and DNA can be selected and edited.  This accomplishment is also sparking ethical debate when it comes to using CRISPR in human research and the treatment of genetic diseases.  In a related article, Chinese scientists were the first in the world to attempt to modify a nonviable human embryo using CRISPR.