AP Biology class blog for discussing current research in Biology

Tag: RIbosomes

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?



The Future of Lung Health

In the 19th century, a tuberculosis outbreak killed every one in seven people worldwide. Scientists believed it to be a genetic disease that mainly children developed making it known as “the robber of youth”. It wasn’t until the year 1882 that Robert Koch’s discovery of tubercule bacillus revealed that tuberculosis was not a genetic disease but highly contagious. Although there was some hesitation in the medical community at first, Koch’s findings helped the U.S. launch massive public health campaigns to educate the public on tuberculosis prevention and treatment. Later in 1904, “William Osler and William Welch, together with Edward Livingston Trudeau, founded the forerunner of the American Thoracic Society, the National Association for the Study and Prevention of Tuberculosis”.  This sparked the beginning of pulmonary research – the conduction of clinically-oriented research into diseases and disorders affecting the lungs and respiratory tract (including molecular and cell-based investigations). With pulmonary research being around for more than 10o years, one would believe discovering something new at this point in history would be a long shot. But, recently researchers at the Perelman School of Medicine at the University of Pennsylvania found RASCs.

TB Culture

RASCs, also known as respiratory airway secretory cells, “line tiny airway branches, deep in the lungs, near the alveoli structures where oxygen is exchanged for carbon dioxide.” Scientists found that RASCs have stem-cell-like properties that allow them to regenerate other cells that are essential for normal functioning alveoli. They also discovered that smoking and the common smoking-related ailment called chronic obstructive pulmonary disease can disrupt the regenerative functions of RASCs. COPD is a chronic inflammatory lung disease that causes obstructed airflow from the lungs. Emphysema and chronic bronchitis are the two most common conditions that contribute to COPD (both bronchitis and emphysema affect the alveoli, the air sacks of the lungs).  The study’s first author Maria Basil, states “COPD is a devastating and common disease, yet we really don’t understand the cellular biology of why or how some patients develop it. Identifying new cell types, in particular new progenitor cells, that are injured in COPD could really accelerate the development of new treatments,”. COPD causes around 3 million deaths worldwide and current treatments can only slow the disease down rather than stop or reverse it. Mice being the common test subjects in lab procedures lack key features of the human lungs, which leads scientists to use healthy human donors to discover RASCs. Since RASCs are secretory cells it means that they produce proteins needed for the fluid lining of the airway. An organelle that we know produces secretory proteins is the ribosome. Ribosomes are tiny organelles that contain RNA and specific proteins within the cytoplasm. Ribosomes are directly involved in the manufacture of proteins by using RNA and amino acids. The discovery of RASCs will not only help advance future COPD treatments but can also lead to discover ways to treat other lung dieases.

Lungs open

Synthesizing More Durable Bulletproof Vests Using Animal Muscle Fibers!

Wait, why? Are Animals harmed? These two may be the first two questions that arise after reading the title. Rest assured that no animals will be harmed since the organism producing these muscle fibers will be engineered microbes. A group of researchers at Washington University’s Engineering school conducted this research that leads to the production of stronger clothing that is more durable which makes it more sustainable because we are no longer using traditional materials like cotton, silk, and nylon.

First, what are Microbes? The National Center for Biotechnological Information states that Microbes are tiny living things that are found all around us and are too small to be seen by the naked eye. “They live in water, soil, and in the air. The human body is home to millions of these microbes too, also called microorganisms. … the most common types are bacteria, viruses, and fungi.” There are many different types of microbes, and there are some that are prokaryotic cells and others that are Eukaryotic cells. The difference between the two is that prokaryotes don’t have a nucleoid region while Eukaryotic cells contain a nucleus that stores DNA. Interestingly in prokaryotes, their DNA is circular-shaped while eukaryotes have linear DNA. In this particular study, they used bacteria, a prokaryotic single-celled organism.

E coli at 10000x, original

Picture of Microbes


 Through synthetic biology, this team modified bacteria so that the microbes were able to synthesize protein to produce muscle fibers. Synthetic biology is where “engineering principles are mixed with biology.” Well, to produce the proteins for muscle fibers, microbes must have ribosomes that synthesize amino acids and combine them to form protein chains. In this particular case, the protein they are synthesizing is titin. “It’s the largest known protein in nature,” said Cameron Sargent, a researcher on the team. It normally consists of 34,350 amino acids.

One of the problems the researchers overcame was controlling how the microbes were able to produce proteins “50 times” the average protein size. They utilized synthetic chemistry on the microbe they engineered to polymerize proteins and form many peptides and other bonds in the process. Peptide bonds, specifically, are covalent chemical bonds linking two consecutive amino acids.

201405 skeletal muscle

Muscle Fibers

My Take

I think this research is very advanced with regard to synthetic biology. If we further develop this field of science, in the future we might be able to synthesize more complex protein structures with simple microbes. I don’t see any bad implications that this research might have on society. I can’t wait to see what Professor Zhang and his team will produce in the future. Sargent  even said, “we can take proteins from different natural contexts, then put them into this platform for polymerization and create larger, longer proteins for various material applications with a greater sustainability.” With applications that are only limited by our imagination, I want to commend Professor Zhang and his team’s effort.

Points to Ponder and Comment:

If clothing were designed out of muscle fibers ethically, would you wear it? Why or why not? What uses do you have envisioned for this field of science if it continues to advance?

Tricky Viruses

Photo Credit: Foto_di_Signorina Flickr

           Strong viruses, such as HIV, make the body work for them. Researchers in Copenhagen have been studying how these viruses manage to take over the body. The virus takes over one cell and then uses the RNA to influence the DNA, giving the virus complete control over the cell. The RNA of the virus is similar to the RNA of the cell. Therefore, the ribosomes of the cell copy the sequence from the virus instead of the actual RNA. This causes the cell to produce the virus’ proteins.

                The RNA of the virus has what is called a pseudoknot. Pseudoknots are places on the RNA that the ribosomes must decipher before it can move on. The pseudoknot holds the sequence for key destructive proteins of the virus and once the ribosome deciphers it, those proteins are produced. This is how HIV can spread so rapidly in the body and can take such a hold over the host; it doesn’t do any of the work.

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