The human nervous system is like a complex circuit board. When wires cross or circuits malfunction, conditions such as schizophrenia or bipolar disorder can arise.
For a long time, scientists have been working to zoom in and identify how brain circuits form so they can learn to rewire troublemaking neurons.
Now, researchers at Stanford led by professor of biology Liqun Luo and professor of bioengineering and of applied physics Stephen Quake have taken a significant step forward in that direction by making a detailed cell-by-cell gene blueprint of the fruit fly’s olfactory neurons. Their work has been published in Cell.
The basic idea behind the research is to understand the neuronal cell types of the relatively simple fly brain, and to identify the molecules that direct the precise wiring of different types of neurons in the fly brain. Over time, researchers want to use a similar approach to study the far more complex cellular makeup of the human brain, and maybe one day even repair the miswiring in brain disorders.
Single-cell RNA sequencing
Reaching back into high school biology, remember that cells have DNA and RNA. DNA is the genetic code that represents the blueprint of an entire organism. The fruit fly, a model organism for the human because it shares approximately 75 percent of our known disease genes, has about 15,000 genes. Of course, not all genes are expressed all the time. Each individual cell expresses a specific subset of genes, which in turn make a specific set of proteins. Messenger RNA molecules carry the genetic codes to create, or express, whatever proteins may be required by any specific cell at any point in time.
The Stanford researchers focused on cells in the olfactory, or smelling, and sensing quadrants of the fly brain. The fruit fly is one of the most studied organisms in biology. Prior experimental research has proven the fly’s olfactory system to be a clean and simple circuit, making it the ideal test bed for developing a new genetic technology to probe how brain circuits are wired up. The smell center of the fly brain has 50 types of central processing neurons that grow threadlike filaments to connect with 50 types…