BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: Cells (Page 1 of 2)

Individual Cells Move Differently When They Are Together

In a groundbreaking study, researchers have unveiled that a protein crucial for powering movement in individual cells operates distinctly when cells collaborate in groups. Cells engage in intricate pushing and pulling interactions with each other and surrounding tissues during processes such as embryonic organ formation, wound healing, pathogen pursuit, and cancer dissemination. The investigation, led by researchers at NYU Grossman School of Medicine, focused on a cluster of 140 cells known as the primordium, observing how these cells generate forces while adhering to each other during movement in zebrafish embryos—a model organism highly valued for its transparency and shared cellular mechanisms with humans.

The study reveals the role of a protein called RhoA, a primary structured protein, in propelling the group forward during embryonic development. As cells strive to move, they extend protrusions and utilize them to anchor onto nearby tissues before retracting them, a process analogized to the casting out and hauling in of an anchor.

Blood Anemia.jpg

In AP Biology, delving into the intricacies of the RhoA protein offers a compelling view of the relationship between structure and function in molecular biology. The distinct domains within RhoA, such as the GTPase domain, Switch I and II regions, insert region, and C-terminal hypervariable region, serve as structural modules that underpin its role as a molecular switch in cellular signaling. The GTPase domain’s proficiency in binding and hydrolyzing GTP is pivotal, causing RhoA’s influence on the cytoskeleton and, consequently, cellular processes like shape modulation, adhesion, and motility. The activation and inactivation, regulated by proteins like guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), displays these cell signaling pathways. RhoA’s dysregulation is a key player in diseases, displaying its integral contribution to maintaining cellular homeostasis. RhoA protein is a monomeric protein, meaning it does not have a quaternary structure.

Senior study author Holger Knaut, PhD, an associate professor in the Department of Cell Biology at NYU Langone Health, expressed surprise at the finding, stating, “This finding surprised us because we had no reason to suspect that the RhoA machinery required to move groups of cells would be different from that used by single cells.”

Prior research had indicated that single cells move forward by activating RhoA at their rear ends, initiating a process involving the motor protein non-muscle myosin II, resulting in cell constriction and detachment from the underlying surface.

Contrary to this, the current study revealed that cells in the primordium activate RhoA in pulses at the front of the cells, where it performs a dual role. At the front tip, RhoA stimulates the outward growth of the cell skeleton (actin meshwork), forming protrusions that grip the surface. Simultaneously, at the base of these protrusions, RhoA triggers non-muscle myosin II to pull on the actin meshwork, retracting the protrusions. This coordinated action propels the cell group forward, akin to the movement of a banana slug along the ground.

Dr. Knaut emphasized, “Our findings suggest that RhoA-induced actin flow on the basal sides of cells constitutes the motor that pulls the primordium forward, a scenario that likely underlies the movement of many cell groups.” He added that while the machinery suggests similarities in the movement of single cells and cell groups, RhoA contributes differently in each case.

Dr. Knaut also noted that a deeper understanding of the mechanisms by which cell groups move holds potential in halting the spread of cancer. He remarked, “The machinery suggests that the movement of single cells and groups of cells is similar, but that RhoA contributes to that machinery differently in each case. Within moving cell groups, RhoA generates actin flow directed toward the rear to propel the group forward.” The study’s findings could guide the design of treatments aiming to block the action of proteins implicated in the spread of cancer.

I personally never knew, especially before taking AP Biology, that cells move together. I did know that they always work together, but not necessarily that they coordinate their movements as a collective entity. It’s fascinating to learn about the intricate processes that govern cellular behavior.

I’ve been particularly intrigued by the role of proteins in these cellular functions. For instance, considering the RhoA protein, what would happen if it misfolded or denatured within our bodies? How would our body react to such a disruption? My assumption is that the consequences could be severe, possibly even leading to a breakdown in essential cellular activities. Could it be so detrimental that it might result in death? I’m curious to hear your thoughts on this matter.

I’ve been contemplating the impact of extreme heat on protein structure. If the RhoA protein were to misfold or denature due to high temperatures, it seems logical that our cells might struggle to move effectively within the body. The idea that external factors like heat could influence such fundamental cellular processes is both intriguing and concerning.

I’m curious about the specific gene responsible for coding the RhoA protein. Are there any specific diseases associated with mutations in this gene? It seems like understanding the genetic aspect could provide further insights into potential health implications.

 

 

Unlocking the Mysteries of the Brain: Bridging Neuroscience and AP Biology

In recent years, neuroscience has unveiled exciting breakthroughs in our understanding of the human brain, revealing its intricate nature. Thanks to the National Institutes of Health’s BRAIN Initiative and the work of the BRAIN Initiative Cell Census Network, we are now diving deeper into the cellular makeup of the brain. This research aligns with our AP Biology lessons on cell structure. It highlights the highly organized nature of nerve cells, reinforcing the concept that cells are the fundamental building blocks of life.

Neuron Cell Body

One remarkable achievement of this research is the creation of detailed cell maps of human and nonhuman primate brains. This development aligns with our AP Biology class, where we have learned about the fundamental concept of cell structure. Cells are, indeed, the building blocks of life, and this research demonstrates how, even in the complex nervous system, all cells exhibit a specific and organized arrangement.

This exploration also highlights the intriguing similarities in the cellular and molecular properties of human and nonhuman primate brains. These shared features reflect our evolutionary history and the conserved nature of brain structure across different species. The research suggests that slight changes in gene expression during human evolution have led to adaptations in neuronal wiring and synaptic function, contributing to our remarkable ability to adapt, learn, and change.

In our recent studies on neurons, we have learned about the fascinating world of these specialized cells. Our understanding of neuron structure and function provides a foundation for comprehending the significance of the research conducted under the BRAIN Initiative. This supports that the brain’s structure is not fixed but adapts to meet the challenges it faces.
The primary goal of the BRAIN Initiative Cell Census Network is to create a comprehensive record of brain cells. This understanding aids in comprehension of the development and progression of brain disorders. By learning the cellular composition of the brain, we can address the challenges that arise when things go wrong, promising a brighter future in the field of brain science.

As we reflect on these intriguing connections between neuroscience and our AP Biology knowledge, it is evident that our class has equipped us with a fundamental understanding of cell structure. This knowledge has proven invaluable in making sense of groundbreaking neuroscience research. I find this as a very intriguing and exciting journey, and scientists are actively committed to understanding the brain’s remarkable adaptability, the key to its functioning and evolution. As we explore the fascinating connections between neuroscience and our AP Biology knowledge, how could this deeper understanding of the brain’s adaptability and structure impact the future of healthcare and treatments for neurological conditions? Feel free to share your views and insights!

How Do Cells Cope With Stress?

Yeast Cell

As humans, our surroundings can make us naturally prone to stress. Whether it’s an overwhelming situation or a big responsibility, there are a plethora of reason that humans become stressed. But have you ever thought about how our own bodies and cells undergo their own kinds of stress? The environment that we are exposed to has an impact on the way that our cells operate, and recent research has provided information about how they can cope with it.

A source from the University of Chicago recently released this article that dives into the facts about the heat-shock of cells and how their adaptation of stress is one of the fundamental processes of life. In fact, this doesn’t only apply t0 our own cells, it also exists in single-celled organisms. The article cites the example of a yeast cell sitting on a bowl of fruit in the kitchen, but as the sunlight begins to warm up the kitchen, the environment becomes less pleasant for the yeast cell. For years, researchers have concentrated on how various genes react to heat stress as a way to understand this survival strategy. Now, because of the innovative application of sophisticated imaging techniques, scientists are obtaining an unprecedented view of the inner workings of cells to see how they react to heat-stress. Cells use a protective mechanism for their orphan ribosomal proteins by preserving them in liquid-like condensates. These proteins are essential for growth but are particularly susceptible to clustering when regular cell processing stops. The condensates are dispersed by molecular chaperon proteins when the heat-shock has passed. This enables the integration of the orphaned proteins into functional mature ribosomes that can start churning out proteins. The cell can resume its work without losing energy thanks to the rapid restart of ribosome manufacturing. This source from The Journal of Applied Physiology studies the importance of thermotolerance and acclimatization and how they allow an organism to survive what would normally be a lethal heat stress. Thermotolerance is defined as an organism’s ability to survive in high temperatures. Acclimatization is an organism’s ability to complete more work in the heat because of improvements in heat dissipation which is brought on by frequent, small increases in core temperature. These two factors of heat adaptation help us to understand the impact of cellular stress on an organism’s adaptation to its environment. In addition, this PubMed mentions how the effects of mild heat stress are just as important as those of severe heat stress. The cellular response to fever-ranged mild heat stress is very substantial from a physiological standpoint. When an organism’s temperature is displaying a fever, the body temperature only increases about 1-2 degrees Celsius. This is helpful information because it can help researchers determine how our cells are affected by illness when our body temperature rises to a fever.

There is plenty to discover about the inner workings of our cells. Our capabilities improve every day, but one thing stays the same: our cells will continue to adapt to heat stress in order to regulate the temperatures of our environment that surrounds us. As we have studied the contents of the cell in AP Bio, we have learned about the roles that the organelles play in the function of the cell. The specific organelles that are involved in cellular stress response are Endoplasmic Reticulum, Golgi Apparatus, lysosomes, and mitochondria. Their role in this process is to connect changes in metabolite levels to cellular reactions. The lipid membranes of organelles sense the changes in specific metabolites and activate the appropriate signaling and effector molecules. Our studies about cells and membranes have taught us about the roles of these organelles, but this research solidifies what we know about cells and can be helpful to understand how metabolism works in our cells.  That is part of what moved me to research this topic. I had never learned anything about cellular stress and how it is regulated, so it was an interesting opportunity to get to learn about it. This research about cell adaptation only adds to the understanding that we have gained from learning about the cell and how it has evolved from its origins. I’m curious to hear your thoughts on the this. How do you think that these recent findings will be helpful for future discoveries in medicine?

 

 

Does Lifestyle and Diet Affect Immune System Aging?

Have you ever heard of the thymus? If not, most people could probably say the same, despite the enormous role it plays in our overall health. The thymus is a small gland in the upper part of the chest that is crucial to the immune systems of children. After puberty, the gland was previously thought to become smaller, gradually turn to fat through a process called fatty regeneration, and lose its function. Through the use of CT scans, a recent study shows that contrary to prior belief, this organ can be significant in adults as well, and the state of it can be influenced by lifestyle, age, and sex.

Diagram showing the position of the thymus gland CRUK 362

The main function of the thymus is to develop all the body’s immune cells before puberty. In order to carry out this function, the gland produces the hormone thymosin. Cells called lymphocytes pass through the thymus where they are fully developed into T cells, with the help of the hormone. Once they are fully developed, they are transferred to the lymph nodes where they help the body fight off infections and prevent autoimmune diseases. Autoimmune diseases occur when an immune system attacks cells from its own body. Have you ever touched your neck when sick and felt a small swollen part? Those are your lymph nodes! When you have an upper respiratory infection, more T cells rush to your lymph nodes to help your body fight off the illness. This is just one example of your immune system in action.

When you think of proteins, what is the first thing you think of? As presented in the AP Biology curriculum, proteins are not just a food group we eat everyday, though they are still very important to ingest! They are part of every cell in our bodies and therefore are crucial to the immune system and the thymus. Immune cells have receptor proteins attached to them that bind to foreign and potentially harmful substances, also called antigens. When the proteins bind to the substance, they trigger the body’s immune system to fight off the antigen. There are two types of immune systems: the innate immune system and the adaptive immune system. The innate immune system fights antigens mostly using killer cells and phagocytes (“eater cells”). The adaptive immune system makes antibodies that are made to fight off specific germs that the cell recognizes.

A new study performed in Sweden looked at the CT scans of 1000 people between the ages of 50-64, and examined the state of their thymuses. The people previously participated in the SCAPIS study which inspected their lifestyles and dietary habits. Results found that 6 out of 10 of the participants had a thymus that was completely turned to fat. It was more common in men and obese people. Dietary habits such as low fiber intake caused more fatty regeneration. People whose thymuses endured more fatty regeneration showed evidence of lower T cell regeneration. Ultimately, the CT scans showed the functionality of the thymus and the immune system. More studies must be performed to fully know whether or not the aging of the immune system affects our health, which is why this research will be expanded to the other 4000 participants of the SCAPIS study.

While people cannot change their sex and age, they can change their lifestyles. This study presents new information that can be used to help people improve their health. For example, I get the common cold once every few months and sometimes the grueling symptoms last for weeks. In the future, I will try to increase my fiber intake over a long period of time, which could possibly lower my chances of getting sick, feeling the harsh symptoms, or having them for a long time. I invite any and all comments to tell me whether or not this information could influence your lifestyle, and how.

Understanding Human Brain Cells

Cells are the basis for all living things. They provide structure and carry out functions necessary for survival. Recent studies have been conducted on the brain, examining the function of the 3,000+ cells found in the human brain. They found the brain to be extremely complex and have found the following: how brains vary among people and the similarities and differences between humans and primates. 

Animal Cell

Unique Brains

Researchers looked at 100 different cells from different brain regions and found cells called astrocytes that use their genes differently based on where they are located. For example, they can regulate blood flow, but also send mitochondria to neurons. They found staggering similarities between 75 brain cells, but they also found differences. It is widely accepted that eukaryotic cells are broken into different divisions to promote productivity. All human brain cells are similar, having an endomembrane system. The staggering similarity is that all cells will consist of a nucleus, ribosomes, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, and mitochondria. This endomembrane system allows parts of the cell to be specialized in a specific function, increasing productivity. Being that cells have different functions, however, cells’ components vary. For example, the brain immune cells, microglia, have unique genes that they use from person to person.

Human Relationship to Primates

Researchers found that cells in the frontal cortex “didn’t differ a lot between primate brains”. While similar, human brains use genes differently from primate brains. Particularly, how cells communicate. It appears that hundreds of genes carry out “human-specific” functions. It is not yet clear as to what exactly these genes carry out. 

The evolution of man- a popular exposition of the principal points of human ontogeny and phylogene (1896) (14594999469)

These new findings are significant for the biological and neurological community, for they add more evidence towards understanding the complexity of the human brain. You may be asking why this matters if there are no definitive answers? Well, we are one step closer to finding an answer. Neuroscience is relatively new. Understanding astrocytes is vital to understanding brain malfunctions. Doctors and scientists will be able to know where the issue is occurring if they understand the anatomy and functions of the brain. Finally, deciphering the similarities and differences between the human brain and primate brain contributes to strengthening Darwin’s evolutionary theory. Given the staggering similarities, the theory seems valid. Scientists noting there are human specific genes suggest why humans are in fact different and more advanced from primates. It is important to stay patient with research for cells, for even small developments are powerful. For example, the Endosymbiont Theory is a dominant theory that also began with seemly small data and breakthroughs.

I find the make up of the human brain fascinating. It’s brilliant how we all share similar brain cells so that we can all function relatively the same. It is truly extraordinary that we all have certain cells in certain spots to conduct different functions. Did you know that simply the location of a cell impacts its entire function? Additionally, the more connections we find between our brains and primate brains, the more likely evolution seems. I am a believer in evolution due to the staggering similarities in our DNA and make up. We share 98.8% of our DNA with chimpanzees! What do you think: did we evolve from apes?

Read it and wheat…

Wheat, corn, and rice are the most important crops around the world. As someone who enjoys baking, wheat is the base of almost all the desserts and bread recipes I bake. However, as I have become more interested in baking various types of bread, I wondered how gluten is formed and how bread textures change based on how long I kneaded the dough. According to Jessica R Biesiekierski in her article “What is Gluten”, Gluten is “complex mixture of hundreds of related but distinct proteins, mainly gliadin and glutenin.” The gluten matrix is essential to the quality of bread dough. It has the ability to act as a “binding” agent and is also used in marinades and even capsules in medication.  The biology of gluten and its structure depend on the ration of glutenin and gliadins. Each component has different functions that can effect “viscoelasticity”. In her article Biesiekiersk, worked to find evidence that “exposure to gluten may be increasing with changes in cereal technology”. There are many diets and intolerances caused by gluten such as the gluten free diet, gluten disorders, coeliac disease wheat allergy and sensitivity. In conclusion of their study, they determined “Gluten is a complex protein network and plays a key role in determining the rheological dough properties and baking qualities.” However, they came across a challenged. They learned that protein structure can “vary dependent on several factors”. Ultimately, make “analysis and definitions difficult”. And overall they conclude that “further work is needed to completely understand non-coeliac gluten sensitive”.

Another study that researched viscoelasticity is by is Peter R. Shewry, Nigel G. Halford, Peter S. Belton, and Arthur S. Tatham studied “The structure properties of gluten: an elastic protein from wheat grain”. According to Science Direct, viscoelasticity refers to a material’s tendency to act like a fluid or a solid. An additional article that explores viscoelasticity.

Vehnäpelto 6

They manipulate the “amount and composition” of HMM subunits concerning the strength or change of gluten structure and properties. These scholars describe wheat as a plant with many properties, however, they emphasized “viscoelasticity”. In terms of this research, viscoelasticity is “the balance between the extensibility and elasticity determining the end use quality.” The scholars use the dough as an example stating that “ highly elastic (‘strong’) doughs are required for bread making but, more extensible doughs are required for making cakes and biscuits”. In the study, these scholars focused on the HMM protein subunits of gluten. At least 50 different types of gluten proteins can be produced during the kneading process; however, these researchers have chosen to focus on the HMM subunits of glutenin. HMM, subunits, X type, and Y type can be only found on one chromosome in wheat cells. These two subunits are 70 % accountable for the viscoelastic variations in bread. This presentation allowed the researcher to see how stable and unstable the subunits were which would play a role in their ability to interact with peptides. In addition, these peptides may relate to the role of gluten in stabilizing the structures and interactions of the subunits.

US Navy 050102-N-5837R-011 Culinary Specialist 3rd Class Joshua Savoy and Culinary Specialist 3rd Class Davy Nugent prepares bread in the bakery aboard the Nimitz-class aircraft carrier USS Abraham Lincoln (CVN 72) Both articles emphasized the importance of protein structure. AP Biology greatly emphasizes the importance of Organic compounds. Proteins have a few structures that are ultimately composed of sequences of amino acids to create polypeptide chains. From primary structure proteins can become more complex by forming alpha helixes and beta pleated sheets. From that point 3D structures can be made. Gluten has a very structure characterized by “high allelic polymorphism encoding its specific proteins, glutenin, and gliadin”. This leads to wheat producing “unique types and quantities of these compounds”, these types and quantities can vary based off “growing conditions and technological processes”.

Self-Assembling Hydrophobic Sandwiches

You read that correctly! Researchers at Rice University in Houston, Texas alongside Jeffrey Hartgerink have made a significant advance in injury treatment, illness education, and drug candidate by testing the self-assembling abilities of 3D printed nanofibrous multidomain peptide hydrogels, referred to as “hydrophobic sandwiches.” 

Hydrogel

The main goal of Hartgerink’s team was to create a structure that could house cells and help them grow tissue by 3D printing the peptide ink. The printing allows researchers to recreate the complexity of biological structures due to their soft and flexible tissue-like feel, making this a major scientifical discovery and advantage. Hartgerink and his team describe their printed peptides as “hydrophobic sandwiches” due to their design, flexibility, and behavior. The peptides were printed to have one hydrophobic side and one hydrophilic side, allowing them to flip on top of each other when placed in water and resemble sandwiches. Like we learned in AP Biology, the hydrophillic qualities of one side will attract water, and the hydrophobic qualities of the other will repel water. Hydrophobic molecules repel water because they are nonpolar molecules, so they are not attracted to water, which is polar. Once the “sandwiches” were stacked after flipping in the water, they formed the hydrogels which can be vital to tissue engineering and wastewater treatments. 

Hydrogel Structure

The multidomain peptides have already been utilized due to their self-assembling nature for regenerating nerves, treating cancer, healing wounds, and encouraging tissue development throughout the body. Rather than only focusing on this aspect of the peptides, Adam Farsheed, a lead author in Hartgerink’s study, wanted to specifically highlight the fact that these peptides are an ideal 3D-printing ink choice due to their self-assembling nature. When testing the “sandwiches,” Farsheed took a unique, brute-force approach to add more of the material, rather than chemically modifying it, to test its function and ability to reassemble itself after deformation. He proved that adding more peptide material lets the peptide reassemble and heal itself extremely well after being deformed. This discovery will make the hydrogels an ideal candidate for scientific and medical usage.  

Through continued testing, he was also able to confirm that the peptides behave differently depending on their charge. The peptide cells with a negative charge tended to ball up on the substrate of the experiment and the positively charged cells spread out and started to mature on their own. Farsheed has confidently stated that their findings will allow the group to “control cell behavior using both structural and chemical complexity.” Both Hartgerink and Farsheed have made incredible contributions to the world of science through their studies using 3D-printed peptide hydrogels. 

 

How To Map A Cell

In order to understand diseases on a cellular level, scientists must learn as much as they can about cells. One of the ways this is done, is through Nanomechanics. Through nanomechanics, scientists can measure many aspects of the cell. They can find the thickness, softness, viscoelasticity, and incompressibility, or how capable the cell is of being compressed. Living cells, specifically eukaryotic cells, are made of a plasma membrane with solids inside of it. The solids can range from proteins, to DNA, to organelles, to much more. As these solids move within a liquid type of mixture, they are considered viscoelastic. Through the use of Atomic Force Microscopy or AFM, a cell’s viscoelasticity can be mapped. Moreover, nanomechanics is able to find the rate at which a molecule spins by using Young’s modulus.

201710 SingleCell

Even further in the cell, scientists can now determine how the lipid bilayer of a cell change. Through AFM, the physical properties of the cell’s lipid bilayer have been seen to change due to the concentration of cholesterol. Low cholesterol regions had a more elastic lipid bilayer, while regions with less cholesterol were less elastic. Additionally, it was observed that during ionization, the elasticity of the lipid bilayer decreases as well.

Cell membrane detailed diagram blank

As scientists reveal more about the cell, they connect what they have learned to diseases. When a cell changes, or organelles it is composed of change, it can be a sign of disease. By looking into cells through ways such as optics-based non-invasive Brillouin microscopy, scientists can study the mechanical properties of cells and the smaller components that compose them. From using this type of technology, scientists have also learned that living eukaryotic cells are one of the softest materials on the planet. AFM uses the forces placed on the cell by the microscope to determine the properties of the cell.

Human eye detail, from- Human eye close up (cropped)

One specific use of nanomechanical mapping on cells is in microsurgeries conducted on the eye. Many ocular diseases are due to a change in the mechanical properties of the eye. Some diseases can be caused by macular holes or macular puckers. Through microsurgeries, the damage to the eye may be fixed. Scientists conducted measurements on cells on a nanometer scale in order to understand what microsurgeries are necessary to be performed. Moreover, nanomechanics allows scientists to understand how the proteins of the eyes work, and how mutations and other tissue can affect the eye. If specific mutations of causes of diseases can be found on a cellular or subcellular level, it would aid in the development of drugs that would be used against the diseases.

How Do Guard Cells Attain Energy?

Ever since we were young, we understood that plants utilize photosynthesis for energy, releasing oxygen in the process. But, we did not learn which parts of the plant actually perform photosynthesis. This is highlighted by guard cells, the cell located in the upper epidermis that controls the concentration of Carbon Dioxide in the plant. So how do they contribute to photosynthesis?

Stomata & Guard Cells

The team of Dr. Boon Leong Lim at HKU wanted to observe the real-time production of ATP and NADPH in the mesophyll cell chloroplasts, which was done by using planta protein sensors in a model plant, Arabidopsis thaliana. This plant is specifically used due to its small genome, short life cycle, simple process to mutagenize, and easily identifiable genes. Shockingly, the Guard Cells Chloroplasts have not detected any ATP or NADPH production whatsoever. Looking for answers, the researchers decided to contact Dr. Diana Santelia, an expert in cell metabolism. Throughout a decade of research and collaboration, they finally have an answer.

Unlike mesophyll cells, photosynthesis in the Guard Cells is inadequately regulated. This is because synthesized sugars from the mesophyll cells are imported into the Guard cells, in which is used ATP production for the opening of the stomata. Additionally, Guard Cells chloroplasts take cytosolic ATP through nucleotide transporters on the chloroplast membrane for starch synthesis throughout the day. At night, though, Guard Cells degrade starch into sugars for the opening of the stomata. Mesophyll Cells, on the other hand, synthesize starch and export sucrose at dawn. Thus, the chloroplasts of Guard Cells ultimately serve as starch storage for the opening of the stomata. Their function is closely linked to that of MCs in order to effectively coordinate CO2 absorption through stomata and CO2 fixation in MCs. 

Although the Guard Cells seem redundant, their role in the overall process of photosynthesis is absolutely necessary. As seen in AP Bio, the stomata are essential for gas exchange for photosynthetic reactions. The stomata’s main role is to take in Carbon Dioxide and release Oxygen, both of which are necessities for the reaction to occur. 

Thank you so much for reading this blog, and let me know what you think in the comments below!

New research exposes and demonstrates how damaged cells survive the cell cycle

In recent news, the Center for Cancer Research have recently discovered a previously unknown phenomenon, which allows certain cells to continue through the cell cycle despite experiencing DNA damage. This also includes past natural safety checkpoints within the cell cycle that are designed to stop the problem from occurring. On January 13, 2021 researchers, in Science Advances, suggested that the timing of DNA damage was crucial for determining whether a faulty cell would survive the cycle.

When cells begin to divide and replicate as part of their natural cycle, they transition from their resting state to one called the G1 phase. In this phase, cells have several important checkpoint mechanisms to ensure that the cell is healthy enough to proceed onto the next stage of the cell cycle. If/when these mechanisms fail due to genetic mutations, cells can progress through the G1 phase unobstructed, which can ultimately lead to cancer.

It was previously believed that cells with DNA damage could not pass through these safety checkpoints in the G1 phase and that the cells would either repair the DNA damage or die. However, scientists helped uncover evidence proving that cells with damaged DNA can actually progress past these critical checkpoints. A team of scientists studied individual cells for days at a time, using live cell time-lapse microscopy, single-cell tracking software, and fluorescent biosensors to detect the cell’s safety checkpoint mechanisms. They added a substance to induce DNA damage for cells of different ages in the cell cycle. Strikingly, the majority of cells seemed to ignore the DNA damage because they failed to trigger the checkpoint between G1 and the next phase, and proceeded into the next phase anyway.

Further investigation revealed that the timing of DNA damage during the cell cycle influenced the likelihood that damaged cells would slip past the checkpoints. The researchers found that the cell’s response to DNA damage is relatively slow compared to the speed of the cell cycle. This means if cells were already very close to the next phase of the cell cycle at the time DNA damage happened, they were more likely to continue into that phase. If the cells were still early in the G1 phase, they were more likely to revert back to a resting state. These observations are a form of inertia, where the cell will continue moving towards the next phase regardless of safety checkpoint signals.

It was also discovered that cells which were genetically identical were more likely to share the same cell cycle fate than non-identical cells. This suggests that factors specific to the cells themselves influence their fate during the cycle, rather than random chance. More studies are needed to understand how these findings apply to cancer. Testing is also extremely important in order to fully understand what the long-term consequences of the checkpoint failures are and find out if the cells that entered the next phase despite considerable DNA damage can become cancerous and eventually form a tumor, which, in my opinion and most likely the opinion of others, will be groundbreaking for cancer research.

Are You Happy With Your Current Cell Provider?

Stem cells are defined as a specific type of cell that is capable of evolving into many different types of cells throughout the human body. Although they may be one of the most promising medical and biological discoveries, not many people know enough about them. The term “stem cell” has actually been dated back to the 19th century, but it wasn’t until 1981 that the first embryonic cells were isolated. In the year 1981, scientists Martin Evans and Gail Martin conducted separate studies and they were able to derive pluripotent stem cells from the embryos of mice.

Why Are They Useful?

In 1959 Physician E. Donnall Thomas conducted the first human hematopoietic stem cell transplant. The transplant was actually conducted on twin sisters. One sister with end stage leukemia received total body irradiation in order to kill the cancer. Soon after, her twin sister donated bone marrow, resulting in the regression of her twin sister’s leukemia. Because of stem cells’ ability to repair, regenerate and develop into specific specialized cell types, they prove to be therapy for many diseases and disorders. People that benefit from stem cell therapy are people who suffer from:

  • Spinal cord injuries
  • Type 1 diabetes
  • Parkinson’s disease
  • Amyotrophic lateral sclerosis
  • Alzheimer’s disease
  • Heart disease
  • Stroke
  • Burns
  • Cancer
  • Osteoarthritis

422 Feature Stem Cell new.png

Types of Stem Cells and Their Therapies

There are three types of stem cells, each with their own respective therapies and uses. The first types are Adult Stem Cells (ASCs). ASCs are found in small numbers in tissues such as bone marrow or fat. Researchers used to think that ASCs could create only similar types of cells. New evidence shows that ASCs may be able to create various types of cells. This means that bone marrow stem cells, for example, could be able to create bone and heart muscle cells. The other kind of stem cells are Embryonic Stem Cells (ESCs). ESCs come from embryos that are three to five days old. These stem cells are pluripotent, which means they can divide into more stem cells or become any cell in the body. This means that ESCs can be used to regenerate and repair diseased tissue and organs. The third kind of stem cells are induced pluripotent stem cells (iPSCs). These kinds of stem cells are ones created in a laboratory and they are a mixture of adult stem cells and embryonic stem cells. Scientists altering genes in adult cells allows them to reprogram the cells into behaving like embryonic stem cells.

 

 

 

 

 

 

 

ITS ALIVE!!! Scientists bring their creation to life.

Cells are the basic units of life, but now scientists found a way to take matters into their own hands and actually create their own Frankenstein of cells. Scientists first created a single-celled organism with only 473 genes five years ago. Unlike the most recent cellular innovation, this simple cell grew and divided into cells of strange and unusual shapes and sizes. In an attempt to fix this, scientists identified 7 genes that when added to the cell, cause them to divide into perfectly uniform shapes. The J. Craig Venter Institute (JCVI), the National Institute of Standards and Technology(NIST), and the Massachusetts Institute of Technology(MIT) Center for Bits and Atoms all together can be accredited with this success.Cell division

How Was It Done?

The first cell with a synthetic genome was created in 2010 by the scientists at JCVI. Rather than building a cell from scratch, they started with cells from a simple bacteria called mycoplasma. The DNA already in those cells were destroyed and replaced with computer designed DNA. Thus lead to the first ever organism on Earth to have an entirely synthetic genome. It was named “JCVI-syn1.0”. Since then scientists have been working on stripping it down and reaching its minimum genetic components. Now scientists added 19 genes into this cell(including the 7 genes needed for proper cell division) and call it JCVI-syn3A. This cell variant also has fewer than 500 genes(a human cell has about 30,000). To find those 7 genes the JCVI synthetic biology group, led by John Glass and Lijie Sun, constructed multiple variants by adding and removing genes. NIST had to observe and measure the changes under a microscope. The difficulty here lay in observing the cells while they were alive, which made imaging them harder because of how small and fragile they were. Even the smallest of force could rupture them. Strychalski and MIT co-authors James Pelletier, Andreas Mershin and Neil Gershenfeld designed a microfluidic chemostat to remedy this. The article by NIST best describes this as a “sort of mini-aquarium where the cells could be kept fed and happy under a light microscope”. They discovered two known cell division genes, ftsZ and sepF, a hydrolase of unknown substrate, and four genes that encode membrane-associated proteins of unknown function, were all required together for cell division. As we learned in AP Bio, organelles like mitochondria and chloroplasts are also autonomous. That simply means that they are self replicating similar to this man-made cell.

 

The ability to create synthetic cells could lead to potential cells that produce drugs, foods and even fuels. Others can detect disease and the drugs to treat it all while being inside your body. It’s amazing to think that humans are capable of creating synthetic life on a molecular level. One can only hope that this power is used for good in the future. Do you believe that what these scientists are doing is ethical or is “playing God” tampering with forces unknown? 

Quit Hogging All the Kidneys

Xenotransplantation is defined as the process of transplanting organs between members of different species. Saying it out loud it sounds like mad science but the it’s not as crazy you might think. Xenotransplantation has actually been a process that has been used for many years, even dating back to the 1960s. This journey began with apes and monkeys. Scientists believe that it would make the most amount of sense to use because they were essentially the most promising source of organs and tissue due to their being primates. However, this unraveled into a series of problems that were due to them being contaminated with viruses that are pathogenic to human beings. Baby monkeys were also researched but the idea was dismissed due to ethical reasons. This consequently led to the study of pig tissue.

We have actually been utilizing things from pigs that most people may not even be aware of. One example of this is pig insulin. It would replace the insulin that your body would usually make in order to get blood sugar into your cells. We obviously can’t take just any part of a pig and use it. We can, however, utilize a pig’s kidneys and transplant it into a human body. On September 25th, scientists and researchers  successfully transplanted a kidney from a genetically altered pig into a human patient and discovered that it functioned normally.

Little piggies

How Did It Work?

According to the an article by the New York Times, the pig needed to be genetically altered in order to be transplanted into the patient. What was altered? Essentially the kidney in the procedure was obtained by removing a pig gene that encodes a sugar molecule that elicits an aggressive human rejection response. Interestingly enough, the genetic difference between pig DNA and human DNA is 98 percent.

What Were The Risks?

While pigs and humans may share a lot of DNA, they are not a match right away. A non altered pig would cause many risks if any part of it were transplanted into the human body. A way it could pose an issue is through the viruses they may contain. Pig viruses may not cause disease in pigs, but they can in fact be pathogenic to humans. The human proteins that are expressed onto the transgenic pig cells can be receptors for viruses. An article on pig DNA from PMC explains that CD55 is a receptor for human Coxsackie B and ECHO viruses (these are relatives of poliovirus), and these cause a disease called myocarditis. The protein CD46 can act as as a receptor for the measles virus, so it is possible that morbilliviruses of animals could be preadapted in the same pigs used for xenotransplantation.

Another way that these transgenic pigs may heighten risk of virus is through viruses with lipid envelopes that are from host cell membranes would be less likely to inactivated by human compliment. What could have been a protective mechanism against infections from viruses derived from farm animals could be broken down in attempts to make xenografts for humans (The tissue or organ being transplanted from the other species).

Slide4kkk

Diagram of a pig kidney

The future of xenotransplantation looks promising. While it may have worked, scientists are still doing studies and still trying to find out more about the viruses pigs may carry. While we can weed out the viruses we are aware of, we still can’t account for the ones we don’t know exist. There is a reason this topic is somewhat new and that is because of ethics. Apes and Monkeys could’ve actually been genetically altered the same way these pigs were, however it was deemed unethical. I personally agree that apes and monkeys shouldn’t be harvested, but that begs the question of whether harvesting organs from pigs is ethical. And with that I ask you what you ate for breakfast, lunch or dinner. Pigs and other animals are already being harvested for food and I believe that if there is a problem with xenotransplants, there would be a problem with the food industry. With that being said, if you’re ever in the market for a kidney, you have options.

Small But Mighty: Sea Otters And Their Leaky Mitochondria

Sea otters: they bob up and down in the water, hold hands when they are sleeping, poop together at social events, stay warm by their fur and leaky mitochondria… wait, what?

Let’s rewind.

Sea-otter-morro-bay 13

A Cute Sea Otter Floating On Its Back

Warm-blooded marine mammals have a thick layer of fat and oils, known as blubber, as their skin layer to insulate their body. In cold waters, blubber helps retain heat and maintain homeostasis.

But what if warm-blooded marine mammals lack blubber? Sea otters are a prime example (and the only example) of a marine mammal without a layer of blubber. Instead, they have a thick coat of dense hairs, 1000x denser than human hair–the thickest on earth. This enables sea otters to trap large amounts of air within their fur coat, acting as insulation. (This is the same reason why sea otters float: the air trapped in their fur coat makes them buoyant).

But with that said, can you stay warm in a fleece jacket? Possibly. What if you were wearing it while in the ocean? That might be somewhat difficult. Similarly, fur can’t solely protect these animals from losing too much heat. These mammals are still living in water, which transfers heat 23 times as efficiently as air. Since sea otters are the smallest aquatic mammals, they have a lot of surface area relative to their volume, making it even harder for these animals to maintain homeostasis.

So how do they do it? Researchers have already understood that sea otters have an extreme metabolism, how food gets converted to energy in cells, eating about twenty-five percent of their body mass in food every day. But the pieces were still not adding up, which prompted researcher T. Wright to investigate this question on a cellular level. He and his colleagues searched for the source of heat in otters’ muscles. Playing a pivotal role in the body’s metabolism, the skeletal muscle makes up 40 to 50 percent of the sea otters’ entire body mass. His study required the collection of tissue from 21 sea otters of different ages and then measured the muscle cells’ respiratory capacity compared to that of other animals. The sea otters’ oxygen flow rate would roughly indicate the measurement of the cells’ heat production.

Mitochondria pump protons across their cell membranes to store energy in the form of ATP, like we learned in AP Biology’s diffusion unit. From this study, T. Wright concluded that the protons are diffusing back through the membrane before being used for work, resulting in excess heat. Since some of the energy is lost as heat, sea otters need to eat more food to compensate for the lost energy. This “leak in energy” is what contributes to the sea otters’ speedy metabolism.

It’s unknown if sea otters develop leaky mitochondria by living in cold water or simply inherit it. Future research into the fascinating design of sea otters may potentially reveal intriguing insight into their evolution, behavior, and maybe someday, their cuteness.

 

 

Can Deodorant Cause Cancer?

Did you ever think you were harming your health while going through your morning routine? Applying deodorant is a daily practice of many people around the world. However, we often don’t realize what exactly we are applying to our bodies and what chemicals the products we are using are made up of. When was the last time you checked the label to see if there were any potentially harmful elements in something as basic as deodorant? Not often, I presume. But I think we all need to start!

The article from Penn Medicine explores the effects the deodorant can have. Deodorant’s contain chemicals which can be absorbed into the body from applying it onto the skin. The theory people have formed about deodorant is that the toxins from the deodorant will collect in the lymph nodes that will turn healthy cells into cancer cells, especially breast cancer as it located closest to the armpit where the deodorant is applied. The difference between a cancer cell and a healthy cell a cancerous cells is a mutation of its DNA (contains the genetic code for organisms). Nucleic acids are DNA. Nucleic acids consist of nucleotides that are made up of a five carbon sugar, a phosphate group and a nitrogenous base. The mutation of the DNA causes uncontrolled cellular proliferation which can occur due to mutations in genes that control cell death and regular cell growth. Healthy cells carry out their ‘normal’ specialized functions. However, the American Cancer Society has said that there is not enough scientific evidence to back the theory. Aluminum is a big ingredient in deodorant needed to prevent sweating. Our bodies ability to sweat is controlled by our nervous system. But how does deodorant really accomplish what it is supposed to? Essentially, the salts in the aluminum have to break down in order to prevent sweat on the pores. The National Center for Biotechnology information claimed that breast tissue does, indeed, have an increase of aluminum in them with daily use of deodorant.

 Harmful Effects of Aluminum on Kidney’s 

A extreme excess of aluminum in the body can result in bone diseases or dementia. Also, a excess of aluminum can also cause kidney issues with people with pre-existing kidney conditions since aluminum gets filtered out of the body through the kidney’s. For the most part, though, there is not enough aluminum in the sticks for it to do enough damage for people with healthy kidneys.

Other Harmful Chemicals Used In Deodorant

Parabens is another ingredient used in deodorant to prevent bacteria from growing on the deodorant, basically being used as a preservative. Parabens also get absorbed through the skin and function as estrogen. Why exactly are parabens bad for us? A excess of estrogen throughout a lifetime, however, can result in increase breast cancer or even a tumor. The positive is that it is in too little of an amount to really make a difference in our bodies.

Just to be safe, though, I think it is time to go buy some aluminum free deodorant- a quick, easy and convenient solution! Here are some great aluminum free deodorants and here are some natural deodorants to get started on using!

Ever Wonder What It Feels Like to Dance In A Cell? Well, You Might Be Able To Find Out.

The never-ending innovations of technology have hit us again, and this time its something very groundbreaking. Recently, the University of Cambridge had partnered up with a 3D image analysis company known as Lume VR Ltd to make a new software called vLume. What is vLume? It’s the future. This new cutting edge technology was developed for scientists to aid them in studying everything from individual proteins to entire cells. How? Well thanks to Lume VR Ltd, vLume allows super-resolution microscopy data to be envisioned and examined in virtual reality.

So you might be wondering, what in the world is super-resolution microscopy? This is basically the reason why we can see such small things in clear high resolution. Essentially, they are approaches to eliminate light diffraction– the slight bending of light which causes low resolution imaging.

 

Why is this such a big deal?

Numerous reasons! For starters, this breakthrough allows us to mingle with the 3D world of biology as if it were up close and in person. Before, we would try to interact with data through a 2D computer screen. Now, we can see a whole 3D view in virtual reality. This new revolutionary imaging software allows scientists to see, question and play around with 3D biological data, seeming like its real, but its in a virtual environment! This is so important because it allows us to find answers to questions we have about biology immensely quicker. This software allows us to make new discoveries in a blink of an eye. Even a PhD student, Anoushka Handa, said, “It’s incredible — it gives you an entirely different perspective on your work.” This is so cool, she took her own immune cell and was able to virtually stand inside her own cell!

This is so amazing, there has to be a catch?

No, there is no catch! Super-resolution microscopy analysis can be very time consuming, but with the vLume software, it was able to cut the wait times significantly which allows the tests to be quicker and ultimately making analysis quicker. All you will need is a VR!

What does this mean going forward?

With this new technology, who knows what’s next. For now, this software will allow us to further understand the world of biology and it might help develop treatments for diseases that we do not have treatments for now. But, in terms of technology, who knows what’s possible. The thought of being able to stand in a cell seemed like fantasy, but it turns out that it is a reality now. We must be cautious, technology seems like it does good, but there can be some harm involved.

My take:

In my non-expert opinion, I think this is a very good sign. This technology is a positive, we can understand more about our world which is very resourceful. I also have emitted my excitement over the course of this article. This is groundbreaking and new which is something I always love to see. The only problem is that people might become reckless with their inventions now. This can be related to our class because we can have a greater understanding of cells and their structure and their functions along with the key organic compounds. Although this tech is used for good, there will be some that’s bad which may be problematic in the future. All in all, this innovation will help us understand ourselves a lot more and it will ultimately be positive in the long run. -Ghohesion

Can your diet’s effect on gut bacteria play a role in reducing Alzheimer’s risk?

Could following a certain type of diet affect the gut microbiome in ways that decrease the risk of Alzheimer’s disease? According to researchers at Wake Forest School of Medicine, that is a possibility.

In a small study, researchers were able to identify several distinct gut microbiome signatures in study participants with mild cognitive impairment (MCI), but not in the other participants with normal cognition. Researchers found that these bacterial signatures correlated with higher levels of markers of Alzheimer’s disease in the cerebrospinal fluid of the participants with MCI. Additionally, through cross-group dietary intervention, the study also revealed that a modified Mediterranean-ketogenic diet resulted in changes in the gut microbiome and its metabolites that correlated with reduced levels of Alzheimer’s markers in the members of both study groups.

“The relationship of the gut microbiome and diet to neurodegenerative diseases has recently received considerable attention, and this study suggests that Alzheimer’s disease is associated with specific changes in gut bacteria and that a type of ketogenic Mediterranean diet can affect the microbiome in ways that could impact the development of dementia,” said Hariom Yadav, Ph.D., assistant professor of molecular medicine at Wake Forest School of Medicine.

The randomized, double-blind, single-site study involved 17 older adults, 11 diagnosed with MCI and six with normal cognition. These participants were randomly assigned to follow either the low-carbohydrate modified Mediterranean-ketogenic diet or a low-fat, higher carbohydrate diet for six weeks then, after a six week “washout” period, to switch to the other diet. Gut microbiome, fecal short chain fatty acids, and markers of Alzheimer’s in the cerebrospinal fluid were measured before and after each dieting period.

The limitations of the study included the subject’s group size, which also accountns for the lack of diversity in terms of gender, ethnicity, and age.

“Our findings provide important information that future interventional and clinical studies can be based on,” Yadav said. “Determining the specific role these gut microbiome signatures have in the progression of Alzheimer’s disease could lead to novel nutritional and therapeutic approaches that would be effective against the disease.”

Each human contains trillions of organisms that influence our metabolism, immune function, weight, and even cognitive health. It is so fascinating to examine the role of gut microbiomes in the progression of Alzheimer’s disease. I believe diets can be very controversial, and I find it interesting to see researchers in this study show how the Mediterranean-ketogenic diet may be effective against Alzheimer’s. However, I am so intrigued to see where these findings may take us with approaches that may be effective against Alzheimer’s, whether they be nutritional or therapeutic approaches.

Nobel Prize awarded to Researchers for Key Discoveries in Cellular Respiration

Recent findings about the change in oxygen levels in cells show new important factors about oxygen that translate to one’s well-being. William G. Kaelin Jr., Sir Peter J. Ratcliffe and Gregg L. Semenza discovered how cells can “sense and adapt to changing oxygen availability,” and are now being awarded the Nobel Prize in Physiology or Medicine. Oxygen is a crucial aspect to how a cell’s functionality. Mitochondria in cells use oxygen to aid in converting food into ATP (energy), a process known as cellular respiration.

A representation of the reaction of cell respiration.

 

Gregg Semenza wanted to further look into the rise of levels of the hormone erythroprotein (EPO), a response to low levels of oxygen, or hypoxia. He found that “oxygen sensing mechanisms were present in virtually all tissues, not only in the kidney cells where EPO is normally produced.” While Semenza analyzing cultured liver cells, Semenza found a protein complex that was unknown to science. He named unidentified DNA segment the “hypoxia-inducible factor (HIF).”

Over the course of 24 years, Semanza continued to explore aspects of HIF and found two different DNA-binding proteins, now named “HIF-1a and ARNT.” Researchers worked with Semanza in finding out which parts of the HIF assist in cellular respiration. While Semenza and Ratcliffe were researching regulation of EPO, Kaelin Jr. was researching von-Hippel-Lindau’s disease (VHL). Kaelin Jr.’s research showed that VHL gene “encodes a protein that prevents the onset of cancer,” and that cancer cells lacking a functional VHL gene have “abnormally high levels of hypoxia-related genes.” But when the VHL gene was reintroduced into cancer cells, “normal levels were restored.” Eventually, Kaelin Jr. and his team found that VHL needs HIF-1a for degradation at normal oxygen levels.

Kaelin Jr. and Ratcliffe both published articles that center around protein modification called prolyl hydroxylation which “allows VHL to recognize and bind to HIF-1α degradation with the help of oxygen-sensitive enzymes.” The papers also wrote that the gene activating function of HIF-1α “was regulated by oxygen-dependent hydroxylation.” The researchers now had a much clearer idea of the effects of how oxygen is sensed within cells.

These groundbreaking finds give the science world more information about how oxygen levels are regulated in cells in physiological processes. Sensing oxygen levels is important for muscles during physical exercise, as well as the generation of blood cells and strength of one’s immune system.

Stem Cells and CRISPR

Many cells can reproduce but there are a few types of cells that are not able to reproduce. One of these types are nerve cells, the cells that cary messages from your brain to your body.  There are many ways nerve cells can be destroyed or damaged, by trauma or drug use.  Millions of people are effected by losing nerve cells and for so long no one could think of a way to recreate them; until the discovery of stem cells.

After fertilization, and when the newly formed zygote is growing, it is made up of a sack of cells.  Some of these cells are stem cells which develop according to their environment. Because of the behavior of stem cells, scientists theorized that if they placed stem cells in the brain or spinal chord, two areas that have an abundance of neurons, the stem cells would turn into a neuron because of the environment it was in.  But, when they tried introducing stem cells into the body, the immune system treated them as an foreign body, as it should. Our immune system has to treat anything that does not come from our body as an enemy or we could get extremely sick.  However, the downside is organ transplants, blood transfusions, etc. are dangerous because they could cause a serious immune rejection.

Someone experiencing a spleen transplant rejection

Cells have a surface protein that displays molecular signals to identify if it is self or foreign.  Removing the protein causes NK (natural killer) cells to target the cell as foreign. Scientist haven’t been able to figure out how to make a foreign cell not seem foreign until Lewis Lanier, chair of UCSF’s Department of Microbiology and Immunology, and his team found a surface protein that, when added to the cell, did not cause any immune response.  The idea would be to use CRISPR/cas9 to edit the DNA of the stem cells, and in doing so would remove the code for the current surface protein and add the code for the new surface protein.

After the scientists had edited the stem cells, to have the correct signal protein, they released them into a mouse and observed that there was no immune rejection. Truly amazing. Maybe brain damage could be helped by this science one day. Tell me your thoughts on Stem Cells in the comments!

For more information, please go check out the primary source of this article.

 

 

Do humans have night vision?

Can humans see in the dark?

If you said yes, you are correct! When I saw the title of Emily Underwood’s article, “How humans- and other mammals- might have gotten their night vision“, it immediately intrigued me. Sight is an amazing gift that we all take for granted. Our eyes are incredible organs, and scientists are now discovering how they work when we see in the dark naturally. That is pretty cool!

Underwood’s article describes a study that gives insight into how our eyes work in the dark. According to her, “On a moonless night, the light that reaches Earth is a trillion–fold less than on a sunny day. Yet most mammals still see well enough to get around just fine—even without the special light-boosting membranes in the eyes of cats and other nocturnal animals.

In broad daylight, mammalian retinas respond to photons, which activate rods, which then send an electrical signal to the brain through a ganglion cell. It was thought that this retinal circuit was the same when the sun went down, but a new study by Greg Field and his colleagues at Duke University proves that the retinal cells adapt when there is no light to create what we know was natural night vision. How?

To understand this new study, we first need to know about direction-selective ganglion cells.

Direction-selective ganglion cells (DSGCs) specialize in motion detection. Depending on the movement of an object, different cells get excited. For example, some DSGCs fire when an object moves up and down and other DSGCs fire when an object moves from left to right. These ganglion cells play an important role in telling the brain where an object is moving towards. By doing this, the brain can make a decision as to how your body should act.

However, in the dark DSGCs behave very differently. Field’s experiments aimed to see how the DSGCs adapt when there is no light. His team examined slices of mouse retinas on glass plates embedded with electrode arrays. In an oxygenated solution, the mouse retinas could still “see” while the arrays recorded the electrical activity of the neurons. They ran the experiment twice: once under a normal “office light” setting, and once by dimming the lights to a moonlight setting. Looking at the results, Field found that three of the four directional DSGCs did not have a response to motion when they dimmed the lights. The only cells that were responding were the ones that usually respond to the motion “up” in daylight. In fact, these cells compensated for the other DSGCs, and were now responding to motions like “down” and “sideways”.

Why were the “up” DSGCs were acting differently? To answer this question, Field genetically engineered mice without intracellular gap junctions to run the experiment again. Gap junctions have previously been associated with night vision, and the results in Field’s experiment confirmed their relationship. The mice lacking gap junctions were not able to adapt to the dark. This shows that gap junctions are critical in boosting motion detection in the “up” cells when there is limited light.

It is still not known why specifically the “up” cells contribute to natural night vision, what do you think?

Field’s findings will be helpful to artificial vision efforts. DSGCs make up 4% of ganglion cells in humans, a small amount compared to 20% in mice. Yet a large part of retinal prosthetics relies on electrically stimulated ganglion cells. Studies like this can fine-tune the technologies that will be able to help visually impaired people, which is why I love reading about them. These experiments are crucial in progressing the future of medicine and the treatment of all kinds of health issues.

Page 1 of 2

Powered by WordPress & Theme by Anders Norén

Skip to toolbar