BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: regeneration

Plant Therapists: Scientists help plants make the decision to regenerate rather than defend themselves after injury

Plants are very susceptible to injury in many forms. They can’t hide from a hungry bunny rabbit or invasive fungi. As humans, we have “fight or flight” instincts, but flight is a tall order for plants. Instead, they have “fight or fix” instincts. When damaged plants have two responses, to repair and regenerate or defend. New York University’s Center for Genomics and Systems Biology decided to perform a study on this known quality of plants.

The defense method is the production of specific compounds, but the scientists’ experiment focused on the regeneration response. “Breeding crops that more readily regenerate and can adapt to new environments is critical in the face of climate change and food insecurity” said NYU professor and leader of the study, Kenneth Birnbaum. The study was split into two parts a study, and an experiment.

Early corn crop

The goal of the study was to understand the relationship between regeneration and defense responses. Does one happen or the other? Can they occur simultaneously? Does affecting one response have a subsequent affect on the opposing response?

The Scientists studied two plants; Arabidopsis and corn. Arabidopsis is common used as a model organism by plant biologists, while corn is the America’s largest crop. The answers they found to the previously posed questions are as follows. In most cases, both responses happen simultaneously and neither are at full strength. When the Scientists manually affected one of the responses, the other response did increase in frequency as a result. As Marcela Hernández Coronado of Cinvestav in Mexico put it, “The ‘fight or fix’ responses seem to be connected, like a seesaw or scales — if one goes up, the other goes down. Plants are essentially hedging their bets after an attack,”

The scientists were able to narrow down the cause of varying level of each response to plant glutamate receptor-like (GLRs) proteins. These receptors are related to glutamate receptors found in the human brain; hence the title of “Plant Therapists”. They learned that these receptors are responsible for regulating regeneration response and in turn, increasing defense response.

Competitive inhibitorConsidering the relationship with neural receptors, the scientists used preexisting drugs meant for these relative receptors. They used neural antagonists to inhibit GLRs. The antagonists are competitive inhibitors, that bind to the active site of the receptor blocking reception of signal molecules. The limited activity of the GLRs made the plants decide to heavily favor regeneration as the signals telling it otherwise were blocked.

The scientists also studied “quadruple mutants” in comparison to normal plants. The plants with mutated GLR had an increased rate of regeneration, further proving the effects of GLR on regulating the ratio between the two responses. Overall however, the plants that were given the neural antagonists were more successful in increased regeneration than the quadruple mutants.

 

 

Harnessing the Power of Regeneration

You at one point might have wished for this superpower after a broken bone. This ability to regenerate is natural to some animals like salamanders and starfish. Recently researchers did the unthinkable; they were able to regenerate a limb for our small amphibian friend. 

Even though you may think that we don’t have regenerative powers, we have the ability to heal from a cut. However, we do not have the ability to regenerate an arm or a leg like a starfish. Instead, when we lose an arm, our body uses scar tissue to cover it. This is a very common mechanism in a lot of animals to prevent blood loss and bacterial infection. 

Researchers at Tufts and Harvard universities worked together to develop a 5 drug cocktail that is used to regenerate their limbs, bones, and nerves instead of just simply clotting it. In their experiment, the animal being tested is the African clawed frog. There are 5 drugs in this process and a silk protein gel. First, the researchers put 5 drugs and the gel in the silicone wearable bioreactor dome that is attached to the frogs’ limbs. Once the drugs are in contact with the stump, the drugs stop the inflammation while also inhibiting collagen production. The importance of stopping collagen production is that it prevents scarring so the researchers can attempt to regrow the limb. The rest of the drugs encourage the growth of nerve fibers, blood vessels, and muscle that makes the limb function as a normal limb. The most amazing thing about this process is that the frog only needs to wear the silicone wearable bioreactor dome for 24 hrs and only be exposed to the drugs once; this will kickstart an 18-month journey of regeneration.

Mitosis cells sequence

A Diagram showing the Interphase, Prophase, Prometaphase, Metaphase, Anaphase, and Telophase in Mitosis.

 

To understand how regeneration is happening, it is crucial to understand the process called mitosis. Mitosis happens when the cell is not in the interphase. If the cell passes the G1, G2, and mitosis checkpoint mitosis and cytokinesis will happen. Mitosis starts as a diploid cell with double-stranded Chromosomes but ends with cytokinesis, resulting in 2 genetically identical daughter cells that are diploid but single-stranded. After this process, the cell will go back to the interphase and G1 phase where the cell grows preparing for its next mitosis cycle. Mitosis is crucial for regeneration since it produces millions of cells in the frog’s body for a new limb to grow. With successful testing on amphibians, Michael Levin, a researcher on this project, said that they will “be testing how this treatment could apply to mammals next.” 

This advancement in medical technology only serves to bring hope to future advancements like limb regeneration of human embryos. With so many people’s lives that can be changed for the better, I cannot wait for the future where we fully harness the power of biology. What do you think about this technology, and do you have ideas for other applications? Are there any downsides that you see?

Regeneration of Lost Limbs in Axolotls

Many salamanders have the special ability to regenerate a lost limb, but adult mammals cannot. The axolotl is a Mexican salamander that is an endangered species in the wild. However, it is unlike most salamanders.

Metamorphosis frog Meyers

Normally, amphibians, like salamanders and frogs, go through the process of metamorphosis which begins with an egg that hatches into a larvae with gills to live underwater. As they gradually reach the adult stage, salamanders and frogs begin to lose and gain certain traits that allow them to adapt from an aquatic environment to a terrestrial habitat.

Axolotl

Axolotls are adorable creatures that are a special species of salamanders. Instead of going to the process of metamorphosis, they go through the process of paedomorphosis in which they retain their aquatic juvenile state for the rest of their life cycle.

Most salamanders have regenerative abilities but none to the extent of the axolotl. Axolotls can regenerate almost any body part, including the brain, heart, lungs, spinal cord, skin, tail and more. This possibly has to do with their juvenile state. Mammalian embryos and juveniles have the ability to regenerate to some extent, such as the heart tissue and fingertips. However, once mammals reach the adult stage, regeneration just simply isn’t the solution anymore. Mammals being to form a scar at the location of injury.

A team of scientists led by James Godwin, Ph.D., of the Mount Desert Island Biological Laboratory in Bar Harbor, Maine, approached the mystery of molecular regeneration by studying the axolotl, a highly regenerative salamander, versus an adult mouse, a mammal that has limited regenerative ability. In this research, Godwin compared immune cells called macrophages in the axolotl to the macrophages in the mouse to identify the factor that contributed to regeneration. It turns out that the macrophages are crucial to the process of regeneration. When the macrophages were depleted in the axolotl, it formed a scar like mammals do instead of regenerating. Macrophage signalling was similar in both axolotls and mammals when exposed to pathogens such as bacteria, funguses, and viruses. However, when the axolotl was exposed to these pathogens, the signalling promoted new tissue growth while in the mouse, it promoted scarring. Continual research of macrophage signalling in axolotls might one day be able to pull us closer to human regeneration.

In the future, when we need to surgically remove parts of our organs, axolotl regeneration might come in quite handy to regrow our important organs!

This research article relates back to AP Biology because macrophages work together with the its lysosomes to break down foreign pathogens. These macrophages will engulf these invading pathogens into intracellular membrane vesicles through the process of phagocytosis. Once entrapped in the vesicles, the pathogens will be killed with acid.

Zebrafish: The Cure to Vision Loss?

Sight is one way in which we, along with many animals, interact with the world. Unfortunately, some people are unable to interact with the world in that same manner. Whether it is hereditary blindness or vision loss due to a neurodegenerative disease, vision loss and eye damage is difficult to fix, especially at a neurological level.

Neurons are present throughout the body and are connected via the nervous system. Their function is to transmit information to the brain and the rest of the body. They do this by signaling other cells by what is called neuronal firing. Individual nerve cells send electrical impulses to others allowing the message to reach other parts of the body. Simply put in the case of eyes and sight, the lens collect and bend the light and that information is sent through the optic nerve to the brain which then processes the information to produce an image. Therefore, if the neurons in the eye are damaged, that information cannot be collected and sent to the brain.

One such eye problem is Macular Degeneration which targets the macula. The macula is the central part of the retina that collects details images from the center of one’s field of vision. Damage to the macula results in a loss of central vision. Those who have it still retain their peripheral vision, but if the case is severe enough, they are deemed legally blind. As of now, there is no known cure.

However, Johns Hopkins Medicine researchers have been studying some animals’ ability to regrow neurons. Fish, along with other cold-blooded animals have the ability to repair eye neurons after injury, and for a long time it was thought that these genes were not present in mammals. According to Seth Blackshaw, professor of neuroscience at John Hopkins University, “[there is] the potential for regeneration is there in mammals, including humans, but some evolutionary pressure has turned it off” (ScienceDaily.com).

Blackshaw’s team has been studying the supportive cells in the back of the eye in zebrafish. These cells, known as the Müller glia, are able to repair the retina by growing neurons. Blackshaw’s team examined the retinal damage and repair of zebrafish, chickens, and mice. They found that while chicken and mice both have the capacity and gene pathways to generate neurons, the transcription factors were blocked so that the neurons don’t regenerate. Blackshaw suspects that the inability to regenerate neurons is due to the fact that animals that are more prone to disease in the brain, or other neurological tissue, may have lost this regenerative ability in order to protect other brain cells.

All of this is very exciting news and I think it is fascinating that studying cells from a fish could potentially help people who suffer from vision loss. I never would have thought that an animal that seems so different from us could help solve a problem that people have been dealing with for centuries. However, I think it is the fact that perhaps we aren’t so different from animals, at least on a biological level, that we are able to study them in order to better understand ourselves. For example, as Blackshaw and his team has discovered, we have those same gene pathways that allow zebrafish to regenerate neurons. And while ours don’t work the same way as of now, they are still present despite years and years of evolution. In the end, I think that the similarities we share with other animals is something to think about.

Bioelectronic Medicine is Moving Fast, Artificial Nerve Regeneration to the Rescue!

 

Researchers at both Washington University School of Medicine and Northwestern have just made a discovery that has huge potential for future patients of nerve damage. Diseases such as Alzheimer’s, Bell’s palsy, Cerebral palsy, and many other illnesses regarding the nervous system/ nerves are one step closer to having a cure! Beyond chemistry and drugs, scientists are now using technology to find a cure using the first ever development of bioelectronic medicine. A device, ” The size of a dime and the thickness of a sheet of paper,” is implanted in the body to “speed nerve regeneration and improve the healing of a damaged nerve”.

This device, which is currently nameless, is powered wirelessly by a “transmitter outside the body that acts much like a cellphone-charging mat”. It is very thin and works by winding around a directly injured nerve(precisely where needed). After the device has engulfed the injured nerves, it delivers electrical pulses. These pulses accelerate wound healing and reproduce nerves. Doctors/ patients using this device have the ability to control the times which pulses are sent. Around two weeks after the device is injected, it naturally absorbs into the body not harmfully.

Image result for nerves

The device has yet to be tested on humans. Recent discoveries have been based on observations on rats with injured sciatic nerves. These nerves in rats send signals throughout the legs to control muscles in feet and legs as well as hamstring muscles. To perform the study, scientist spent ten weeks monitoring rats’ recovery while providing pulses one hour per day for one, three, six, or no days at all a week. After a little more than three months, researchers concluded that “any electrical stimulation was better than none at all at helping the rats recover muscle mass and muscle strength”, and the device accelerated the regrowth of nerves. They also concluded that “the more days of electrical stimulation the rats received, the more quickly and thoroughly they recovered nerve signaling and muscle strength”. Overall, no side effects of the device and its reabsorption were found.

Overall, this discovery can do great things for the human population. Making it extremely convenient, this device after put on can possibly replace pharmaceutical treatments for a variety of medical conditions in humans

Researchers are currently continuing to study this device to see what is most effective in animals similar to humans. They are evaluating the effectiveness of the devices different sizes,  duration, and fabrication.

Just Keep Swimming…and Fixing Paralysis!

 

Zebrafish (Danio rerio)

Zebrafish (Danio rerio)- from Flickr

The zebrafish may just look like a cute aquatic animal, but they actually have a unique power that humans don’t: they can heal a severed spinal cord. While this uncanny ability sounds almost magical, it can be explained by the work of a certain protein, CTGF (connective tissue growth factor), that humans have as well. Because of this commonality, recent research conducted by Duke University suggests that by learning from the mechanism that allows the Zebrafish to do this, humans may eventually be able to regenerate their lost spinal tissue!

Essentially, the zebrafish is able to regenerate their spinal cord by forming a cellular bridge across the damaged or missing area. They can be fully healed in as little as 8 weeks! But how is this “bridge” possible on a molecular level? When the fish get injured, dozens of genes get activated. Seven of these genes code for proteins that are secreted from cells. The researchers at Duke found that CTGF, one of these proteins, is crucial to the bridge-making process. They found this by looking at the glia, which are the supporting cells that help initially form the bridge before the arrival of nerve cells. After forming the bridge, CTGF levels rose marginally in these glia. When the researchers genetically deleted CTGF from the glia, the whole regeneration process failed. This research proved exciting because humans also have a very similar form of CTGF, and when they added this human-version of the gene to the glia, regeneration was even faster, only taking 2 weeks! The researchers even discovered which of the four parts of CTGF was the important one in this regeneration phenomenon, which in the future would make it easier to create therapies modeled after this part for humans.

However, using this knowledge to help human tissue regeneration is not as straightforward as it may seem. Mammals such as ourselves form scar tissue around damaged areas, complicating the matter further. The group plans on experimenting with other mammals, namely mice to compare and contrast their CTGF levels with those of zebrafish. Do you think that CTGF research is the best way to achieve human tissue regeneration? Is there any way to prevent scar tissue from forming around our wounds? Let me know in the comments!

 

Original Article: https://www.sciencedaily.com/releases/2016/11/161103142321.htm

Photo Credit to Tohru Murakami: https://flic.kr/p/nb2gGH

New Stem Cell Discovered in Brain

Credit Isaac Mao, http://www.flickr.com/photos/isaacmao/544928/

At Lund University, researchers have discovered a brand new type of stem cell in the adult human brain, which is thought to be responsible for the regeneration of muscle, bone, cartilage, and adipose tissue.

Stem cells are known for their ability to proliferate into several different cell types, providing a plethora of research opportunities for medical researchers.  These specific stem cells, found near small blood vessels in the brain through the analysis of brain tissue from biopsies, have also been identified in other locations of the body.  In other organs, the stem cell appears to have a similar structure, and is responsible for repair and wound healing, leading scientists to suggest that the curative properties may also apply to the brain.

The next step is to better understand this new type of stem cell, and to learn how to better control and enhance its self-healing properties.  “Our findings show that the cell capacity is much larger than we originally thought, and that these cells are very versatile,” said Gesine Paul-Visse, Ph.D., Associate Professor of Neuroscience at Lund University.

With a more thorough understanding of how this stem cell operates, researchers hope to use it to better treat neurodegenerative diseases and stroke.

As Paul-Visse puts it, “Ultimately the goal is to strengthen these mechanisms and develop new treatments that can repair the diseased brain.”

For more information, read the article “New stem cell found in the brain” http://www.biologynews.net/archives/2012/04/23/new_stem_cell_found_in_the_brain.html

Or look for the original study published in the journal PLos ONE.

So, what do you think?  Will this new stem cell found in the brain make an important impact in neurobiological research?

Powered by WordPress & Theme by Anders Norén

Skip to toolbar