Bill Brieher and bacterial rockets
Bill from Tim Mitchisons lab showed me some wild movies and images of bacteria rockets (my term, not his). It turns out that certain bacteria invade our cells and push themselves though the cytoplasm by taking contol of parts of the internal scaffolding of the cell. This scaffolding is called the cytoskeleton, and one of its components is actin in the form of actin filaments. These filaments help the cell move and keep its shape.
When the bacterium Listeria, often guilty of causing food poisoning and present in yummy blue cheeses, gets into the cell, it takes control of nearby actin. First it causes the actin to grow filaments around it in a messy ball, then suddenly it shoots off with a trail of actin filaments behind it. The filaments grow behind the bacteria, pushing it forward, and dissipate behind it. Bill is trying to understand what causes the actin to grow and shrink.
The cell is looking more and more like an ecosystem, with tiny bacteria taking rides on actin rockets.
Bill also talked to me about one of his first significant papers about the glue that holds cells together. If you take a sea cucumber and push it through a wire mesh, the cells with reform a sea cucumber. Unbelievable but I guess true. This won't work on animals with more structure, like a mouse (and hopefully no one has tried), but an interesting thing happens if you do it to an early-stage mammalian embryo. You end up with something with skin cells on the outside, muscle cells on an inner layer, and gut cells in the inside. It dies, of course. Ok, I get a little squimish here about these experiments, but let's forge ahead. The 'interesting' part is how the cells know how to aggregate. The theory is that similar cells have glue proteins on their membranes that only stick to cells with similar glue proteins. So all the skin cells have one, unique protein and so only stick to other skin cells. Same with muscle cells and belly cells. Interesting.
When the bacterium Listeria, often guilty of causing food poisoning and present in yummy blue cheeses, gets into the cell, it takes control of nearby actin. First it causes the actin to grow filaments around it in a messy ball, then suddenly it shoots off with a trail of actin filaments behind it. The filaments grow behind the bacteria, pushing it forward, and dissipate behind it. Bill is trying to understand what causes the actin to grow and shrink.
The cell is looking more and more like an ecosystem, with tiny bacteria taking rides on actin rockets.
Bill also talked to me about one of his first significant papers about the glue that holds cells together. If you take a sea cucumber and push it through a wire mesh, the cells with reform a sea cucumber. Unbelievable but I guess true. This won't work on animals with more structure, like a mouse (and hopefully no one has tried), but an interesting thing happens if you do it to an early-stage mammalian embryo. You end up with something with skin cells on the outside, muscle cells on an inner layer, and gut cells in the inside. It dies, of course. Ok, I get a little squimish here about these experiments, but let's forge ahead. The 'interesting' part is how the cells know how to aggregate. The theory is that similar cells have glue proteins on their membranes that only stick to cells with similar glue proteins. So all the skin cells have one, unique protein and so only stick to other skin cells. Same with muscle cells and belly cells. Interesting.
