Featured Scientist:
Dave G.

Graduate student in Genetics

Name: Dave G.

Birthplace: Worcester, Massachusetts​

Field of Study: Genetics and Epigenetics

What organism do you study?: Humans

Favorite thing about science: Learning about the molecules that all work together to make up the extremely complex thing that is the human!

Fun Facts: I’m one of the hosts for a science news podcast called Goggles Optional, and I once broke my nose trying to kiss the Blarney Stone in Ireland.

Say "Hi" on Twitter! @DaveGennert

Dave's Science

“How do our cells use the same DNA to do very different things?”

The series of A, T, C, and G letters that makes up your DNA holds the instructions for making every type of cell in your body.  But each of your cells needs to know which parts to read and which parts to ignore.  You wouldn’t want a skin cell to make brain cell parts! How does a cell figure this out?  It turns out that the instructions for when to read each part of the DNA is also hidden within the DNA code.

The DNA strand in every one of your cells is very tightly crumpled up in order to fit into the tiny nucleus.  Parts of that DNA molecule that need to be used are compacted much less tightly than the parts that aren’t needed.  This allows the molecular machinery inside your cell to read only the parts of the DNA it needs to. You can think of it like a giant library.  There may be a huge number of books packed away on the shelves, but there are some books that are out on displays, ready to be read immediately.

The body consists of many types of cells, but they all carry the same DNA sequence. Source: Printable Diagrams

In every cell, parts of the DNA can be in a closed configuration (left) and are hard to read or open (right) and easy to read. Adapted from Bio-Rad image here

Each type of cell has a unique set of sequences in this “open” configuration.  Some sequences are open only in muscle cells, some sequences are open only in bone cells, and so on…  Even within the same type of cell, two cells may have very different parts of their DNA in the open configuration.  I study T cells, which are cells in the bloodstream that are important in the immune system. When T cells are actively fighting an infection, they have a different set of open DNA sequences than T cells that are resting or looking for bad stuff to fight.

In my research, we can pick out T cells that don’t fight as effectively and compare them to T cells that are really good at fighting for a long time.  Which parts of their DNA are more open? Which parts are more tightly compacted? This gives us clues about why some T cells are better at their job than others.  If we want to use T cells as a way to treat diseases, we’ll need to know how good they will be at their job. We could also use that information to point us to important parts of the DNA of T cells, which we can modify in the lab to make them better at fighting infections or cancer.

Colorized electron micrograph of a T cell

Source: NIAID

What questions is Dave asking?

I love exploring the human genome– all the information for making every part of a human is encoded in the DNA molecule in every cell.  Each cell needs to very carefully regulate how it uses the DNA to make only what it needs. This is what I’m asking with my research:

  • Where in the DNA sequence is the information telling the cell which parts it needs?

  • How is a functional T cell different from a non-functional T cell, on the DNA level?

  • What happens if we change a non-functional T cell’s DNA look like a functional T cell’s DNA?  Does it start acting like a functional T cell?

Do you have any questions about genetics or DNA? The immune system? Being a genetics researcher? Ask me by clicking below!

The structure of DNA within a chromosome.

Marx, V. Reading the second genomic code. Nature. 1 Nov 2012.

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