The Sterilization of Mosquitoes

Many infamous viral disease such as malaria, Zika, dengue, West Nile, and yellow fever are all carried and transmitted to new hosts by mosquitoes. For many years researchers have been looking for ways to prevent the spread of these dangerous viruses, and they often target mosquitoes. One method is to sterilize mosquitoes, thus reducing the amount of carriers. Male mosquitoes can be sterilized by infecting them with a certain bacteria (Wolbachia) that modifies their sperm. When a Wolbachia-infected male mates with an uninfected female mosquito, his sperm kills the eggs after fertilization. When the infected male mates with an infected female, her modified egg is compatible with his modified sperm, and the eggs survive.

While this sterilization method is being used, scientists didn't really understand all the mechanisms underlying how it works. To understand why this bacteria causes sterilization, a group of scientists from Vanderbilt University pinpointed two genes in Wolbachia called cifA and cifB and inserted them into male fruit flies. They found that these males could no longer reproduce with normal female flies, but just like in the mosquitoes, they could still reproduce with infected females. The infected females "rescue" the modified sperm which reminded scientists at the Yale School of Medicine of antidotes and toxins. They used simple yeast cells to test this hypothesis and put the "toxin" gene into the yeast, which resulted in the yeast cells dying. On the other hand, when they put both the "toxin" and "antidote" genes into the yeast, they survived.

These experiments in both fruit flies and yeast mirror what is happening in mosquitoes. Since the discovery of this gene pair, researchers have considered adding extra copies of these genes into bacteria, creating a "super Wolbachia" that more potently sterilizes the mosquitoes. Yet, this could "essentially crash the population" said coauthor of the fruit fly study Seth Bordenstein. While the creation of bacteria with multiple copies of the genes has not yet been attempted, this research unveils the genes responsible for the sterilization of mosquitoes, and helps fight against the spread of viral diseases.

Link to news article: https://www.sciencenews.org/article/bacteria-genes-offer-new-strategy-sterilizing-mosquitoes?mode=topic&context=87

Gene-Editing Policy

A group of experts recently met to discuss the use of gene-editing. This group from The National Academies of Sciences and Medicine issued a recommendation on Feb. 14th stating that altering germline cells (such as eggs, sperm, and embryos) should be allowed if the editing cures genetic diseases, but does not enhance health or abilities. Germline cells are reproductive cells, and any genetic modification in these cells will be passed on to future generations- a very useful tool for curing a disease in not just one person, but their future offspring. Co-chair of the recent panel Alta Charo, says "We are not trying to greenlight heritable germline editing...We're giving it a yellow light." In other words, the panel of experts is trying to find the special circumstances in which the use of germline editing is justified by a very great need for its healing potential. Some examples of these special cases would be curing cystic fibrosis or Huntington's in someone, and thus eliminating the disease from any of their future offspring.

This recent recommendation, for allowing germline editing in certain cases, goes against a global summit's previous recommendation that gene-editing should not be used in the germline. Many scientists fear that allowing any form of germline editing would open the floodgates for other, less necessary, applications (such as designing a baby's eye-color or increasing athletic ability). Marcy Darnovsky, director of the Center for Genetics and Society in Berkeley, says “Once you approve any form of human germline modification you really open the door to all forms...I’m feeling very unsettled and disappointed by what they are recommending.”

Clinical trials that would produce heritable changes in the human genome are currently banned in the U.S. Still, the debate about germline gene-editing rages on, and this recent recommendation may pave the way for a change in policy.

Link to Science News article:
https://www.sciencenews.org/article/human-gene-editing-therapies-are-ok-certain-cases-panel-advises?mode=topic&context=87

Chimera: Hosts to Other Species

In Greek mythology, the Chimera was a fire-breathing hybrid creature with parts from more than one animal (imagine a creature with the body of a goat, dragon wings, and a lion head). In the scientific world, animal hybrids are called "chimeric" and receive their name from this mythical creature, but unlike their namesake, exist in reality. One area of research involving the use of chimeric animals has the ultimate goal of growing human organs in these animals, and then transplanting them into humans.

While this research is still very young, several studies of chimeric mice, rats, and pigs, suggest that using one organism to grow an organ of another species, is a viable method for curing disease. One particular study published in Nature, showed that mouse pancreases could be grown in rats. The healthy insulin-producing cells from the mouse pancreases were extracted from the chimeric rats, and transplanted into diabetic mice, which cured the mice of diabetes. The transplanted cells allowed the mice to maintain normal blood sugar for more than a year, giving scientists much hope for the future of this research.

In another study, pig embryos were injected with human stem cells, with the hope of using pigs to grow human organs for disease treatment. Unfortunately, the researchers found that the human cells likely interfered with normal pig development, since only a small percentage of the pig embryos were capable of continuing development for about 28 days. Currently, scientists are working to improve the growth of human cells in pig embryos, and there is hope that one day humans can benefit from this medical technology using chimeric pigs.

Link to news article:
https://www.sciencenews.org/article/mouse-cells-grown-rats-cure-diabetes-mice?mode=topic&context=87

Chimeric mouse embryo containing rat cells (shown in red)

Synthetic DNA Bases

Life's natural genetic code is made up of 4 DNA bases represented by the letters A, T, G, and C. These 4 bases pair to form base-pairs (A-T and G-C). These base pairs have been rearranged to create all types of organisms (penguins, bears, whales, humans, plants, bacteria etc.). In other words, life as we know it is made from these 4 DNA bases.

Scientists from The Scripps Research Institute in California have created 2 new DNA bases they call X and Y. These new bases form a base-pair and have been incorporated in an entirely new organism. The new type of bacteria they created still contains the usual A, T, G, and C bases, but also has the new bases (X and Y) in its genome. This new bacterium has been called the first "semisynthetic organism."

While this new bacterium has no practical applications at this point, the lead researchers on this project suggest that these new bases can allow single-celled organisms to take on new properties, potentially helping scientists create new drugs. We can be comforted by the fact that this technology is only intended for use in single-celled organisms, and we won't be seeing these new X and Y bases showing up in more complex organisms.

Link to article about this research:
https://www.sciencedaily.com/releases/2017/01/170123214717.htm

Sight Restored Using Stem Cells

Stem cells have an amazing potential to heal, but a challenge is ensuring the transplanted cells survive long enough to work. Long-term studies of stem cell therapies have been performed in a variety of model organisms. Notably, researchers from the Buck Institute have provided one of the first demonstrations of long-term stem cell therapy efficacy. They transplanted photoreceptors (cells for receiving light signals), derived from human stem cells, into blind mice and observed long-term vision restoration. They found that even 9 months after injection, the mice were able to perceive light signals (something they were completely incapable of prior to the treatment).

This awesome example not only shows the great potential of stem cell therapies for healing, but can help scientists further develop stem cell therapies that circumvent immune rejection. Dr. Lamba, senior author on the paper, says "That finding gives us a lot of hope for patients, that we can create some sort of advantage for these stem cell therapies so it won't be just a transient response when these cells are put in, but sustained vision for a long time."

Link to article:

https://www.sciencedaily.com/releases/2017/01/170112141243.htm

Genome Editing Trials

For the first time, the exciting gene-editing tool CRISPR-Cas9 has been used in a human. This technology, which I wrote about several weeks ago (refer to post from Nov. 5 for more detail), allows scientists to alter DNA bases to introduce a change to any gene. The concept of altering human DNA is controversial, but the potential health applications are practically limitless. For example, if a disease is caused by a specific, known mutation, scientists could potentially alter that mutation, thus treating the disease. This technology is a hot topic among biologists, and is also currently one of the most-studied tools.

Cancer is one of the main diseases that scientists hope can be treated using CRISPR-Cas9. Because of this, the first use of CRISPR-Cas9 has been in a human patient with aggressive lung cancer. Scientists of the West China Hospital in Chengdu have altered a gene that normally prevents a cell from launching an immune response, so that the immune system is more likely to target and destroy cancerous cells. The researchers hope that after injection into the patient's blood stream, the modified cells will then start attacking the cancerous cells. 

While this Chinese trial, the first of its kind, began in October of 2016, the United States also plans to start a human trial of CRISPR-Cas9 early this year. The U.S. trial is also testing the safety and efficacy of using CRISPR technology to combat several forms of cancer. Since both China and the U.S. are launching CRISPR-Cas9 trials, some healthy competition is predicted to fuel the potentially life-saving research. Carl June, a scientific adviser to the U.S. trial, says "I think this is going to trigger 'Sputnik 2.0,' a biomedical duel on progress between China and the United States, which is important since competition usually improves the end product."

To watch a video and gain more information about this Chinese trial, follow this link:

http://www.usnews.com/news/national-news/articles/2016-11-17/gene-editing-tool-crispr-cas9-used-in-a-human-for-the-first-time

Synthetic Stem Cells

Stem cell therapies have the potential to treat many different diseases and help many people. One way these therapies work is by helping damaged tissue repair itself. Still, there are risks associated with these therapies including immune system rejection, and potentially cancerous growths. Additionally, natural stem cells are fragile, and must be treated with extreme care, which slows therapies and adds another element of risk. To circumvent some of these limitations, scientists are developing procedures that use synthetic stem cells, instead of natural cells.

Scientists from North Carolina State University, the University of North Carolina at Chapel Hill, and First Affiliated Hospital of Zhengzhou University, created synthetic cardiac stem cells, and implanted them into mouse hearts that had been damaged by heart attack. Usually, the damage that heart attacks inflict upon heart muscles are never repaired by the body. Yet, when the researchers injected the synthetic stem cells, they found that the previously damaged heart muscles were effectively repaired, and this repair was comparable to when natural cardiac stem cells are implanted.

These findings are very promising for the future of stem cell research and therapies. Compared to natural stem cells, the synthetic stem cells are more stable and can be modified for use in different parts of the body. Unlike natural cells, the synthetic versions are incapable of replicating, which reduces the risk of tumor formation. And since the synthetic stem cells are designed to bypass the patient's immune system, they are far less likely to be rejected by the body's immune system. Ultimately, using synthetic stem cells instead of natural stem cells may be more affordable and accessible, and could eliminate some of the dangerous side effects associated with stem cell therapies.

To read more about the research done here, check out the following links:

http://wallstreetpit.com/112614-worlds-first-synthetic-stem-cells-implanted/

https://news.ncsu.edu/2016/12/synthetic-stem-cells/

The Skin Gun

A whole field of research revolves around harnessing the power of stem cells to treat many different injuries and ailments. Recently, CNN released an article about a skin gun that sprays a patient's healthy skin stem cells onto severe burns. The goal is to completely heal the severe burns, much faster than typical healing, using the patient's own stem cells.

Developed by a New York biotech firm called RenovaCare, this "CellMist System" requires just about a square inch of unwounded skin. To summarize the process, the patients' healthy skin is removed, the stem cells are isolated from the other skin tissue, suspended in a water-based solution, and sprayed onto the wound where the new skin hopefully begins to grow. The stem cells are not modified in any way, simply isolated and sprayed onto burn wounds.

This skin gun seems to hold much potential for healing burn wounds. While still an experimental treatment, the President and CEO of RenovaCare, Thomas Bold, says "We've seen already a couple dozen patients, and we're very happy about the results." See some results of this treatment for yourself, by watching the video at the link below.

Link to watch the video and learn more:
http://www.cnn.com/2016/12/07/health/skingun-burn-care-technologies/

Myostatin Mutations

Many people strive to be stronger. There are even those who spend hours working out daily and eat high-protein diets to sustain their muscle growth. When we see someone that is completely ripped, we may think something along the lines of "Do they even have time for anything else?" While muscle growth does typically require much effort, if genes involved in muscle growth are mutated in a specific way, then muscles can be altered without a shred of intentional effort.

       Such is the case in Belgian Blue cattle (image below). These cattle have been selectively bred for many years since muscle mass in cattle often means more meat and money for breeders. For a long time, the more muscular bulls and cows were chosen for breeding, and this resulted in more muscular offspring. What breeders didn't necessarily understand, was that they were selecting mutations in the myostatin gene. This gene codes for the protein myostatin which inhibits muscle development. The mutated, shorter form of myostatin doesn't function properly, which results in more rapid muscle growth. This creates "double-muscled" offspring that, instead of having the normal amount of muscle fibers at birth, actually have twice as many muscle fibers. The myostatin mutation is considered a permanent muscle mutation within this cattle breed.

But myostatin has the same muscle-inhibiting function in other mammals. Mutations of myostatin have even been found in humans. Several cases of children born with these mutations have been documented, but have only recently been understood (image of boy with a myostatin mutation below). Additionally, myostatin mutations have been induced in mice to create "mighty mice" by Se-Jin Lee and colleagues at Johns Hopkins. Below, there is an image of a normal, wild-type mouse that lacks any myostatin mutation and a mouse with mutated myostatin. You can clearly see that the mutated mouse has much more muscle mass than the normal mouse. The discovery of myostatin mutations and their effect on increased muscle mass has practical applications. These mutations are currently being studied to potentially help people with muscular dystrophies (conditions with weakening muscles).

Link to primary article about Myostatin mutation:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC24998/

Can you Ear me now?

Doctors in China are growing a new right ear for a man who lost his in a car accident. Not in a petri dish in a lab, but on the man's own arm! Dr. Guo Shuzhong, a reconstructive surgery specialist, is leading a team of doctors in a 3-part plan. In the first phase, the skin was expanded on the patient's arm using injections of water. In the second phase, some of the patient's own cartilage, shaped into the form of an ear, was placed into the arm to grow. In the third and final phase, the doctors plan to transplant the new ear onto the patient's head.

This isn't the first case of ears being grown on arms. An Australian artist by the name of Stelarc elected to grow a third ear on his arm for the sake of art. Although the ear isn't yet used for hearing, he plans to pursue further operations to install a Wi-Fi enabled microphone so that people can "tune in" to his station and listen to whatever his ear is hearing (image of Stelarc and his ear below).

Link to recent reconstructive ear story:
http://www.foxnews.com/health/2016/11/10/doctors-grow-man-new-ear-on-arm.html

Link to video of this reconstructive process:
http://www.wsj.com/video/chinese-doctors-grow-new-ear-on-man-arm/37480AB0-9361-4354-B75E-6C7CB273FED2.html

Link to 2015 Stelarc story:
http://www.cnn.com/2015/08/13/arts/stelarc-ear-arm-art/

Thanksgiving, Wine, and Bluebirds

Thanksgiving has come and gone, and we all likely feasted on turkey or ham, stuffing, potatoes, pumpkin pie...and maybe a glass or four of wine. Since wine is so often enjoyed, and wine-making can be very profitable, many researchers out there are studying what makes wine better. Still, before grapes are even collected, they are obviously grown in vineyards. A recent study looked into how vineyards may benefit from other animals in the environment: bluebirds.

Unfortunately, trees that house bluebirds are frequently cut down to make room for expanding vineyards. This study examined whether putting up birdhouses (for the bluebirds to live in) is beneficial to vineyard owners. To do this, they collected fecal samples from many bluebirds in Napa Valley, and analyzed the poop for DNA fragments (a process they called "molecular scatology"). The researchers used readily available databases to match the DNA fragments they found in the bluebird poop to the DNA of known species. In other words, they figured out what the birds had been eating.

When they compiled their findings, the researchers saw that bluebirds generally eat a lot of herbivorous insects (mosquitoes and other species), and only about 3% of their diets are from predatory or useful insects. From the standpoint of winemakers, this is a really good thing! It means that the bluebirds are consuming the insects that could potentially eat or damage their crops. Also, we didn't know that bluebirds eat mosquitoes (insects that are not just annoying, but also can spread harmful viruses). These findings might encourage winemakers to install more birdhouses, which would benefit the birds, the winemakers, and all of us happy consumers of wine.

Check out this link to learn more:
http://www.popsci.com/bluebird-poop-proves-their-value-to-california-vineyards

We Are What We Eat

A very recent study by scientists at the University of Oxford reveals an interesting link between organisms and what they eat. To build DNA, an organism must have access to all the right components. If an organism has a restricted diet, and has limited DNA components, then it would make sense that their DNA would be different from an organism that did not have this limited diet. This was the scientists' hypothesis: the composition of food could alter their DNA.

To test their hypothesis, they examined similar groups of parasites that shared a common ancestor but have evolved to eat different food. The researchers developed mathematical models to make DNA comparisons and found that parasites with low-nitrogen diets had DNA sequences composed of less nitrogen than parasites that ate nitrogen-rich food. Interestingly, they also found that it's possible to predict diets of related organisms by comparing their DNA. The authors believe their findings shed light on the mystery of how two highly related organisms can have very different DNA, and also recognize that there are many other factors that influence the DNA of organisms.

Link to review article: https://www.sciencedaily.com/releases/2016/11/161115111720.htm

Primary Reference: 

1. Emily A. Seward, Steven Kelly. Dietary nitrogen alters codon bias and genome composition in parasitic microorganisms. Genome Biology, 2016; 17 (1) DOI: 10.1186/s13059-016-1087-9