Can Whales And Dolphins Fight Cancer?
Whales and dolphins have been shown to be better at fighting cancer than we are, and now we may be closer to understanding why cetaceans (鲸目动物)do it. Cetaceans are generally the oldest living mammals, and some cetaceans have reached their 200th birthday. Their size means their bodies contain far more cells than the human body.
“If you have more cells that means that one of those cells has an increased risk of becoming cancerous.” says Daniela Tejada-Martinez at the Austral University of Chile. “So, if you are big or live longer, you have thousands and millions of cells that could become harmful.”
“There’s a joke that whales should be born with cancer and not even able to exist because they’re just too big,” says Vincent Lynch at the University at Buffalo, New York, he says there is a super trivial explanation for how whales can exist. “They just evolved better cancer protection mechanisms,” he says.
Now, Tejada-Martinez and her colleagues have studied the evolution of 1077 tumor suppressor (肿瘤抑制)genes (TSGs). In all, they compared the evolution of the genes in 15 mammalian species, including seven cetacean species. Genes regulating DNA damage, tumor spread and the immune system were positively selected among the cetaceans.
| A．They also found cetaceans gained and lost TSGs at a rate 2.4 times higher than in other mammals. |
| B．If the whale gene was injected into the human body, could humans fight cancer? |
| C．Some people deny that cetaceans can increase TSGs faster than other mammals. |
| D．Why this happens remains a mystery. |
| E．In contrast, cetaceans have much lower cancer rates than most other mammals. |
| F．But we still need to learn more about why and how they did this. |
2 . 
The Paint Creek Recreation Trail is the flagship pathway of a planned trail network in the Ohio counties of Fayette, Ross and Highland. Nearly 35 miles of paved trail are currently open linking the communities of Washington Court House, Frankfort and Chillicothe.
The vast majority of the trail occupies a former railroad corridor acquired by the local nonprofit trails group in 1994. However, the trail does leave the original corridor where the right-of-way could not be acquired from its current owners. The diversions are usually short, with the longest stretch being a 2.5 mile stretch of highway cast of the Washington courthouse.
Because most of the trails through rural Ohio are dominated by seemingly endless fields, trail users are exposed to the sun for long periods of time. Fortunately, the path occasionally winds through a more wooded corridor near local waterways, such as Paint Creek and the Scioto River.
The Paint Creek Recreation Trail also passes through the downtown areas of the three towns along the way, offering many opportunities for rest and energy. Just before Chillicothe, trail users will want to stop at Hopewell Culture National Historical Park. The Hopewell Mound Group, a part of the park visible from the trail along Sulphur Lick Road, features earthworks and tombs built by the local people nearly 2,000 years ago.
The existing Paint Creek Recreation Trail will one day make a significant contribution to local leisure and transportation. There are plans nowadays to develop new trails along former railroad corridors from Washington courthouse northwest to the existing Xenia-Jamestown Connector, southwest to Wilmington and cast to Circleville in Pickaway County.
1. Which of the following is true about the trail?| A．Most of the trail is not well remodeled. |
| B．Most of the trail used to be a railway passage. |
| C．Most of the trail goes through the centers of 13 towns. |
| D．Most of the trail is close to the local railway lines. |
| A．It will take on a new look. |
| B．It will be part of a national historic park. |
| C．It will be bought by a nonprofit company. |
| D．It will play an important role in leisure and transportation. |
| A．An American website on travel. | B．An English scientific magazine. |
| C．A lecture by a professor of geography. | D．A travelers' notebook. |
