1.   And it does so through a chemical pathway that most plants have the ability to use.

2.   It is very unlikely, scientists agree, that the precise chemical pathways from which life arose will ever be known.

3.   Scientists have discovered molecular causes of appetite and satiety, unraveling elaborate chemical pathways that control how much animals, including people, eat.

4.   Other researchers were more cautious, noting that addiction is a complex process in humans because it is linked to learning and multiple chemical pathways in the brain.

5.   Scientists who did not participate in the study said its systematic approach could be useful in determining the chemical pathways of other disorders.

6.   Researchers working with mice reported today that they have identified a way to block a chemical pathway that tumor cells use to spread to surrounding tissues and organs.