AP Biology class blog for discussing current research in Biology

Author: rayceptor

A New Mosquitoes Exterminator: CRISPR

Mosquitoes might be just pesky little insects that might start appearing again in a few months. They leave their saliva in your skin, and this causes an itchy bump. But in other parts of the world. Estimates report that mosquitoes have killed up to 52 billion people in history by spreading malaria, yellow fever, and dengue. It is currently killing 1 million people per year, even with advanced medicine and healthcare around the world. Doesn’t that horrifying statistic shock you? 

Aedes aegypti

A close shot of Aedes aegypti

To drastically lower this number, researchers took a smart approach and decided to eliminate the source of the problem. They decided to use CRISPR to genetically alter the male flies so that they become sterile.  Professor Craig Montell from UC Santa Barbara altered the gene of Aedes aegypti, the main type of mosquito that transmits dengue, yellow fever, Zika, etc. 

Previously, scientists just radiated and applied chemicals to sterilize male mosquitoes in hopes to alter their genes since “there are enough genes that affect fertility that one will likely be altered,” making them infertile. However, this would leave, many of the mosquitoes to be sick and die prematurely since other genes that don’t relate to fertility are also changed.

Using CRISPER/Cas9, researchers removed B2t, a gene that specifically affects male fertility in mosquitoes. Unlike in previous efforts, the sterile mosquitoes were completely healthy. 

This whole effort to sterilize insects is part of a greater method called the sterile insect technique (SIT). Scientists release way more sterile insects than there exist in the wild. The population will crash as females will not be mating with a lot of males that are capable of making offspring. A benefit of releasing males instead of females is that males feed on nectar, not blood,  so it will not cause major disturbance to communities.

To sexually reproduce, a sperm cell must meet an egg. Each gamete is a haploid that has a single set of chromosomes. The sperm and egg combine to produce a zygote making it a diploid with a complete set of chromosomes. If a male is sterile, then they are not able to produce or release their sperm, making it impossible for those insects to reproduce.

The effect of this technique is more effective after each cycle, so when you release the same amount of mosquitoes after 3 cycles, the population change will be way more drastic. A downside to this is that sterile male mosquitoes need to be reintroduced after they die off since they cannot pass on their mutated gene.

Although researchers have successfully identified a way to isolate the gene and remove it to make male mosquitoes fertile, they still needed to find the optimal ratio of lab mosquitoes to wild type to ensure that they do not wipe out the species in an area since that has dramatic effects on the whole ecosystem. The researchers conducted many trials and found that, in a week, a ratio of about “5 or 6 sterile males to one wild-type male” decreased female fertility by 50% while, a ratio of 15:1 suppressed female fertility to about 20%, where it leveled off. So depending on the situation, they now release the more precise amount. 

I think that this is one of the brilliant uses of CRISPR, and it only goes to show how far we can go if we master this technique. An ethics question that this research brings up is, do humans have the right to wipe out an entire species just because it is causing harm to humans?

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?

Why to Get the Vaccine and Booster Shot!

The COVID-19 pandemic started almost 2 years ago on December 12, 2019.  Since then, it took roughly 1 year to release a vaccine in the US. So far there are almost ~780,000 deaths in the US with 195M US citizens fully vaccinated or 59.1% of the US population. Now booster shots are available to ages 18 and older in some parts of the country, you might wonder if you should take them. Is there an incentive to?

Firstly, the ultimate goal of the COVID-19 Vaccine is to stimulate the B-memory cells so when someone comes in contact with the same pathogen, there is faster antibody production for infections. The antibodies bind to the COVID-19 virus in an attempt to inactivate them, and the virus will then be engulfed by the macrophages. In a recent study, a team of physicians and public health experts measured the effectiveness of the COVID-19 vaccine over time. They sampled health workers at San Diego Health use in their study. When the subjects got vaccines in March, their early effectiveness for preventing the contraction of COVID-19 was around 90 percent; however, by July, this percentage had fallen to approximately 65 percent. This is an expected response for most viruses. The immunity wanes over time since the memory B cells’ protection against the virus begins to decrease with time because there are just fewer memory B cells specific to the pathogen present in your body. Thus, booster shots are given to remind the body’s immune system about the COVID-19 virus and produce more memory B cells. In a time where delta was the most prevalent virus, the study also found that unvaccinated people were 7 times more likely more to test positive for COVID-19 compared to unvaccinated people, and adults who contract COVID-19 are 32 times likely to require medical attention compared to vaccinated adults who contracted COVID-19. Again, we have to keep in mind, this is not a simple random sample of the whole US population, therefore we cannot fully use these results to reflect what will happen in our community.

Now that we went over the reasons to get the booster, we have discussed what the booster shot is. The booster shot in essence is the same formulation as the current COVID-19 vaccine that you received if you are vaccinated. The only little variation is in the Moderna’s shot: it is half the dose of the initial vaccine. The shot injects mRNA in a Lipid nanoparticle that can bypass our cell membrane because of its small size and nonpolar properties.


Lipid Nanoparticle containing mRNA

The mRNA is used by the cell’s ER to synthesize spike proteins. Since it’s the same formula as the previous COVID-19 vaccines, this means that the booster doesn’t guarantee immunity against the delta and omicron variants. However, it does retrigger your memory B Cells. You should get the booster shot around 6 months after full vaccination since there is a big decreased effectiveness with the passage of time.

Novel Coronavirus SARS-CoV-2 Spike Protein (49584124196)

Covid’s Spike Protein

With new variants around the corner, Chira Alleles, a co-author in the study stated “Similar findings [in this study] are being reported in other settings in the U.S. and internationally, and it is likely that booster doses will be necessary.” Since there is no huge downside to getting the shot, and if you do not have any underlying health conditions that might put you in more danger than getting COVID-19, I strongly think you should get the booster shot as soon as it is available to you!

What are your thoughts on getting the vaccine/booster shots? Do you think there will be a point where we can achieve herd immunity, or will that be impossible with the rapid mutations?

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?

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