A breathtaking trick potentially left over from our ancestors might be found in us -- the ability to sense oxygen through our skin. Amphibians, animals such as frogs that can live both on land and in water, have long been known to be capable of breathing through their skin. In fact, the first known lungless frog that breathes only through its skin was discovered recently in the rivers of Borneo. Now the same oxygen sensors found in frog skins and in the lungs of mammals   have unexpectedly been discovered in the skin of mice. "No one had ever looked," explained Randall Johnson, a biologist researcher. Mice and frogs are quite distant relatives, so the fact they have these molecules   in common in their skin suggests they might well be found in the skin of other mammals, such as humans. "We have no reason to think that they are not in the skin of people too," Johnson said. These molecules not only detect oxygen, but help increase levels of vital red blood cells, which carry oxygen around the body. Normal mice breathing in air that is 10 percent oxygen--a dangerously low level similar to conditions at the top of Mount Everest, and about half that of air at sea level. However, mice that had the oxygen sensor HIF-1a genetically removed from their skin failed to produce this hormone   even after hours of such low oxygen. These findings, if they hold true in humans, suggest one could raise the level of oxygen circulating inside the body. This could help treat lung diseases and disorders such as anemia   without injecting drugs, which make up a multibillion-dollar market, Johnson said. Athletes also often try to get more oxygen delivered to their muscles in order to improve their performance. They often do this by training at high altitudes or in low-oxygen tents. The new study suggests they might want to expose their skin as well as breathing in low-oxygen air to improve their performance. "It's hard to say what exactly might be done, however--there's a lot we don't know yet," Johnson explained. The scientists detailed their findings in the April 18 issue of the journal Cell. The best title of the passage may be   _  .
Humans Might Sense Oxygen Through Skin Frogs And Mice Are Distant Relatives First Known Animal Breathes Through Skin Great Findings Benefits Athletes A Lot
Question: A breathtaking trick potentially left over from our ancestors might be found in us -- the ability to sense oxygen through our skin. Amphibians, animals such as frogs that can live both on land and in water, have long been known to be capable of breathing through their skin. In fact, the first known lungless frog that breathes only through its skin was discovered recently in the rivers of Borneo. Now the same oxygen sensors found in frog skins and in the lungs of mammals   have unexpectedly been discovered in the skin of mice. "No one had ever looked," explained Randall Johnson, a biologist researcher. Mice and frogs are quite distant relatives, so the fact they have these molecules   in common in their skin suggests they might well be found in the skin of other mammals, such as humans. "We have no reason to think that they are not in the skin of people too," Johnson said. These molecules not only detect oxygen, but help increase levels of vital red blood cells, which carry oxygen around the body. Normal mice breathing in air that is 10 percent oxygen--a dangerously low level similar to conditions at the top of Mount Everest, and about half that of air at sea level. However, mice that had the oxygen sensor HIF-1a genetically removed from their skin failed to produce this hormone   even after hours of such low oxygen. These findings, if they hold true in humans, suggest one could raise the level of oxygen circulating inside the body. This could help treat lung diseases and disorders such as anemia   without injecting drugs, which make up a multibillion-dollar market, Johnson said. Athletes also often try to get more oxygen delivered to their muscles in order to improve their performance. They often do this by training at high altitudes or in low-oxygen tents. The new study suggests they might want to expose their skin as well as breathing in low-oxygen air to improve their performance. "It's hard to say what exactly might be done, however--there's a lot we don't know yet," Johnson explained. The scientists detailed their findings in the April 18 issue of the journal Cell. The best title of the passage may be   _  .
A. Humans Might Sense Oxygen Through Skin
B. Frogs And Mice Are Distant Relatives
C. First Known Animal Breathes Through Skin
D. Great Findings Benefits Athletes A Lot
Answer: