Cell Biology – TylerJFord.com

April 8, 2019April 8, 2019

Delving into SciComm by Tyler’s Instagram stories: Biosensors, Komodo dragons, lab meat, and more!

Stories from the SciComm by Tyler Instagram account

I often come across interesting biology facts. I spam these facts in polite conversation, but I’ve also decided to share them in a more productive way on Instagram. On the SciComm By Tyler instagram account, I’ll post detailed drawings coupled to nuggets of biological intrigue. Some of these will come from blog posts. Through the stories feature, I’ll share more bite-sized biological morsels. I’ll couple the stories with goofy doodles (sometimes I’ll recycle these from my gallery :P). At the end of each week, I plan on delving into the stories in a little more detail through a blog post.

Below, I expand on my first week of stories. Enjoy!

Please follow me on Instagram if you like what you see :D.

Biosensors are biological machines that detect objects and events

I wrote a bit about biosensors in an older blog post. As a refresher, biosensors are biological machines that detect specific objects and events. They have many research uses. They can detect chemicals, they can detect organisms, and some can even count how many times cells divide.

I first became enamored with biosensors during my PhD work. For part of my work, I tried to get bacteria to turn sugar into gasoline. To see if my bacteria were accomplishing this goal, I designed a biosensor. This biosensor made the bacteria turn red if they produced gasoline-like chemicals. Indeed, the more gasoline-like chemicals they produced, the more red they’d become. Unfortunately, my biosensor wasn’t particularly sensitive so I abandoned it (such is the nature of many experimental research projects!).

Others have created more useful sensors. The doodle above illustrates a biosensor that detects DNA. Such biosensors bind to specific DNA sequences and glow. They help scientists understand how DNA sequences interact with other things in cells. Using many different biosensors, scientists learn how cells function. Scientists can then use their knowledge to create therapeutics or even design cells that do cool things like attack cancer cells!

Komodo dragons use venom to kill prey

I think Komodo dragons are super cool. Even if they don’t breathe fire, they’re still basically dragons. Long ago, I was told that Komodo dragons don’t directly kill their prey. Supposedly, they instead transferred bacteria to their pray through biting. The resulting infections then killed their prey over time. Recently, I learned that RESEARCHERS DO NOT BELIEVE THIS ANYMORE. Indeed, when I was at the San Francisco Zoo a few days ago, I read that Komodo dragon bites inject venom into their prey. This venom kills prey through a mixture of physiological effects. For instance, the venom can lower blood pressure and prevent clotting. It’s not fire, but it’s pretty brutal!

Some frogs survive being frozen

Okay, I’m a molecular and cell biologist at heart, but I love me a good animal fact! I picked this one up while watching one of the many BBC nature documentaries on Netflix. I don’t have much more information than what’s in the image. I just think it’s really cool! Hopefully, I’ll dive into this in a dedicated post at some point.

Some bacteria inject DNA into plants

Doodle of an agrobacterium injecting DNA into a plant

Bacteria do soooooo much more than make us sick. There are many bacteria that do good things. We’ve even figured out how to turn some dangerous bacteria into useful tools. For example, there are bacteria that use teeny tiny needles to inject their DNA into plant cells. These bacteria naturally cause plant diseases. However, scientists have figured out how to use these bacteria to deliver useful DNA sequences to plants. They can even use these bacteria to make crops resistant to pests! Learn a little more about plant biotech in this post.

Complex meats are hard to make in the lab!

Many companies are working to grow meat and meat-like products in the lab. They hope to produce these “meats” more sustainably than livestock. They are having a lot of success growing meats like chicken nuggets or ground beef. However, it will be some time before we have more complicated meats like steaks or pork chops. The complex structures of these meats are difficult to create in the lab.

That’s all for this week. Please follow me on Instagram to check out my stories in real time. Cheers!

March 26, 2019March 26, 2019

Pigs: the future heroes of organ transplantation?

Way back in 2017, I wrote a post about how scientists might one day use pigs to grow human organs. These “human-pig chimeras” could provide replacement organs to people with diseases like diabetes.

I recently learned that researchers are also trying to make pig organs suitable for transplant into humans. Their work doesn’t rely on putting human cells in pigs; they don’t need to make chimeras. Instead, these researchers use genetic engineering techniques to make pig organs more acceptable to the human body. Their modifications prevent the immune system from attacking and rejecting the pig organs. Thus, they hope to make pigs the future heroes of organ transplantation.

This research holds a lot of promise for patients in need of organs. Yet, it’s reasonable to worry that we devalue pigs by using them to produce human organs. My take is, if we accept pigs are sources of food, we should accept them as sources of organs. Nonetheless, I believe that we should develop transplant and food systems that don’t rely on living animals. Learning how to grow organs in pigs may help us move in this direction. Hopefully, we’ll eventually know enough about organ development to simply grow organs (and meat for consumption) in the lab.

Caricature of a pig pancreas — One day we may be able to transplant pig pancreases (pigcreases?) like this to patients in need.

March 16, 2019March 23, 2019

Receptors – critical biological parts hijacked by viruses

“Receptor.” It’s yet another bit of biological jargon. It sounds like receptors should be small spacecraft launched to defend an alien mothership. Or maybe receptors are courtly underlings who receive guests before their presentation to the queen? In truth, receptors are cool and important biological structures that reside on cell surfaces.

As you might remember from my post on cell membranes, the layers of fat that surround cells are quite complex. They are studded with proteins that perform many functions. Some of these proteins are receptors.

Receptors all detect stimuli and cause cells to respond in some way. Often, receptors grab onto specific molecules floating nearby. Then they signal to the cell that they’ve done so.

The exact cellular response to a receptor signal depends on the receptor and on the stimulus detected. Some signals cause cells to grow. Others cause cells to move. Still others coordinate behaviors among many cells. Receptors are critical for many of life’s complicated processes.

Unfortunately, receptors have a darker side too. Many viruses use receptors as handles. With a good hold a on receptor, a virus can barge into a cell. Thus viruses hijack receptors to infect cells and cause disease.

Drawing of a virus grabbing onto a receptor to infect a cell. — A virus grabbing onto a receptor to infect a cell.

Using receptor biology to prevent viral infection

Interestingly, scientists are using receptors to fight viral infections. They reason that, if they get rid of receptors used by viruses, the viruses will have no way of infecting cells. Many receptors are only important under specific circumstances. Thus, getting rid of them will have some small negative consequences, but the benefits of resisting viral infection are worth it.

Indeed, a scientist in China recently claimed to have modified babies to make them resistant to HIV (these are the so-called “CRISPR babies”). This scientist used a genetic technique to delete one of the receptors hijacked by HIV. The researcher performed this technique in embryos. Thus all the modified babies’ should be able to pass their modifications to their offspring.

What this scientist did was foolish for many reasons. Some of them include:

It is unclear if the technique was safe.
It is unclear if the technique accomplished its goal.
There are effective ways to prevent HIV transmission that don’t require this technique.
Some types of HIV use other receptors. Thus, the children won’t be protected from all types of HIV.

On top of all this, the scientist’s use of this technique raises many ethical questions. Most of these stem from the fact that the babies can pass on their human-designed modifications to their offspring. Should we modify the human gene pool in this way? Do we know enough about the potential consequences? Can we use similar techniques to do more than treat disease? Society at large must face all of these questions before we decide to use any similar techniques again.

This unfortunate work aside, other techniques modify receptors on adult cells. Future generations can’t inherit the modifications. Thus we can use these techniques following standard regulatory rules. Indeed, clinical trials using modified adult cells to treat HIV have had very promising results! Scientists can also give immune cells receptors that make them better at fighting cancer (see my previous discussion of CAR-T cells in this post). Receptors play a role in so many biological processes that we’ll likely see many more cool uses of them soon!

The next time you see a picture of smooth, round cell, remember that it’s studded with receptors and they do a lot!

January 8, 2019March 18, 2019

Transcribing copies at the genomic library

Cartoon of a cell with a library representing the genome.

Your cells require lots of certain proteins in order to function properly. For example, your brain cells use proteins to transmit electrical signals, your muscle cells use proteins to contract, your stomach cells use proteins to secrete acid, and so much more.

Your genome contains the DNA instructions for these proteins in the form of genes. Almost all of your cells contain two complete copies of your genome and therefore two copies of each gene (one from your mother and one from your father). With only two copies of each gene, but the need to create large amounts of certain proteins, your cells need to make more copies of particular genes. This post discusses how cells make copies of genes to drive the differential production of proteins that ultimately leads to various cellular functions.

The genome as the library in a cellular city

Think of your cells as tiny cities that together make up the country that is your body. These cities have their own specialized roles that collectively help the country (body) function properly. To carry out its role, each city has its own specific mixture of workers. Some cities have more builders, others more farmers, others more tech entrepreneurs, and so on. These workers are like the proteins in your cells.

A Cell City with its genomic library poised to distribute mRNA transcripts of its books… I mean genes.

The libraries in these cities are like your genome. They contain all of the books required to train all of the types of workers that could possibly exist in a city. However, there are only two copies of each book. Because some cities require many more plumbers than dentists, they cannot simply loan out the two books and expect all of the their needs to be met. Instead the library creates copies of each book. The more copies of a particular book the library creates, the more of that type of worker the city can train. If the city needs more actors than philosophers, its library can simply make more copies of the acting books and fewer copies of the philosophy books. In fact, the library can stop creating some copies altogether and the city will have very few of that type of worker.

Transcribing genes into mRNA copies

Your cells work in a similar way. The instructions found in the two cellular copies of your genes are required in disparate amounts, in different places, and at different times. To account for this, your cells don’t create proteins by following the instructions in genes directly, instead they transcribe the genes into copies known as mRNA. Cells then use the mRNA copies to produce much more of the encoded proteins when they’re needed. Indeed, if your cells don’t need any of a certain type of protein, they can simply stop transcribing mRNA copies of the gene that encodes it.

Our various body parts take on their different roles through transcription. Brain cells transcribe specific genes to transmit electrical signals. Muscle cells transcribe specific genes to contract. Stomach cells transcribe specific genes to secrete acid. With transcription, we’re much more than blobs of cells all doing the same thing.