科學(xué)一刻 腦和粘液
Have you ever been to a lake or a pond and felt that slippery slime that’s all over the rocks. It has a lot more in common with the human brain than you might think.
The human brain contains about 86 billion nerve cells, or neurons. They signal to one another electrochemically to control our behavior. They can do this because the outer membranes of neurons have special proteins called ion channels.
They allow electrically-charged atoms, or ions, to cross the cell’s membrane. There are special ion channels for sodium ions, potassium ions, and calcium ions, and other kinds, too. They cause electrical signals to form and spread over the cell membrane. But, what does all this have to do with pond slime?
Work Through The Same Channels
That slimy coating on the rocks is called a biofilm, and it’s a highly organized community of billions of bacteria. The bacteria coordinate their activities and share resources, and that cooperation requires long range communication.
Ion channels are part of a molecular tool kit shared by many kinds of cells. This tool kit is very ancient and goes all the way back to the common evolutionary ancestor of most living things today. In 2015, a team of scientists reported that bacteria use potassium ion channels to create electrical signals that travel from cell to cell over long distances across biofilms, and allow the cells to coordinate their activities.
Even pond slime, it appears, has a kind of crude brain.
