Researchers have long puzzled over why a gene known as brain-derived neurotrophic factor (BDNF), which is crucial to the ability of neurons in the hippocampus to grow and connect to each other -- forming the basis of memory and learning -- produces two different transcripts, which then each fabricate identical proteins.

In the July 11 issue of Cell, the scientists report the answer, and it has to do with transportation. They found that the longer of the two transcripts (messenger RNAs, or mRNAs) include extra sequences that "motor" molecules attach to, in order to move the information far away from the nucleus of the cell and toward the long, tree-like branches of the nerve cell known as dendrites. There, protein-synthesizing machines use that mRNA to produce protein that helps small protrusions (called dendritic spines) on these dendrites grow.

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