With only about 1，000 pandas left in the world，China is desperately trying to clone the animal and save the endangered species.That's a move similar to what a Texas A & M University researchers have been undertaking for the past five years in a project called “Noah's Ark”．

Noah's Ark is aimed at collecting eggs，embryos(胚胎)，semen and DNA of endangered animals and storing them in liquid nitrogen.If certain species should become extinct，Dr.Duane Kraemer，a professor in Texas A & M's College of Veterinary Medicine，says there would be enough of the basic building blocks to reintroduce the species in the future.It is estimated that as many as 2，000 species of mammals，birds' reptiles will become extinct in over 100 years.The panda，native only to China，is in danger of becoming extinct in the next 25 years.

This week，Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit.They are now trying to implant the embryo into a host animal.The entire procedure could take from three to five years to complete.

“The nuclear transfer(核子移植) of one species to another is not easy，and the lack of available panda eggs could be a major problem，” Kraemer believes.“They will probably have to do several hundred transfers to result in one pregnancy (having a baby)．It takes a long time and it's difficult，but this could be groundbreaking science if it works.They are certainly not putting any live pandas at risk，so it is worth the effort，” adds Kraemer，who is one of the leaders of the Project at Texas A & M，the first－ever attempt at cloning a dog.

“They are trying to do something that's never been done，and this is very similar to our work in Noah's Ark.We're both trying to save animals that face extinction.I certainly appreciate their effort and there's a lot we can learn from what they are attempting to do.It's a research that is very much needed.”

Winter begins in the north on December 22^nd. People and animals have been doing what they always do to prepare for the colder months. Squirrels(松鼠), for example, have been busy gathering nuts from trees. Well, scientists have been busy gathering information about what the squirrels do with the food they collect.

They examined differences between red squirrels and gray squirrels in the American state of Indiana. The scientists wanted to show how these differences could affect the growth of black walnut(黑胡桃) trees. The black walnuts is the nut of choice for both kinds of squirrels. The black walnut tree is also a central part of some hardwood forests.

Rob Swihart of Purdue University did the study with Jake Goheen, a former Purdue student now at the University of New Mexico. The two researches estimate(估计) that several times as many walnuts grow when gathered by gray squirrels as compared to red squirrels. Gray squirrels and red squirrels do not store nuts and seeds in the same way. Gray squirrels bury nuts one at a time in a number of places. But they seldom remember where they buried every nut. So some nuts remain in the ground. Conditions are right for them to develop and grow the following spring. Red squirrels, however, store large groups of nuts above ground. Professor Swihart calls “death traps for seeds”.

Gray squirrels are native to Indiana. But Professor Swihart says their numbers began to decrease as more forests were cut for agriculture. Red squirrels began to spread through the state during the past century.

The researchers say red squirrels are native to forests that stay green all year, unlike walnut trees. They say the cleaning of forest land for agriculture has helped red squirrels invade Indiana. Jake Goheen calls them a sign of an environmental problem more than a cause.

One day, “supercharged plants” may help feed people around the world. Supercharged plants are ones that grow faster than normal plant life. Scientists can speed up the growth by modifying, or changing, the structure of plants' genes. The modifications make them react quickly to changes in light. This all has to do with photosynthesis(光合作用), the process in which plants turn sunlight, carbon dioxide and water into food.

Plants grow fastest in the sun. That is when they make the most food for themselves. But their rate of growth can slow when things like clouds or trees block sunlight. But when the sun returns, it can take many minutes for growth to speed up again.

This can be a problem because it means some of our most important crop plants are not as productive as they could be. Researchers say demand for food is expected to increase up to 70 percent by the middle of the century. They also note rising temperatures on Earth's surface. That is why they are looking for ways to improve photosynthesis and make plants more productive.

Steve Long is a plant biologist at the University of Illinois. He wanted to find a way to help plants get back up to speed quickly after a period of darkness. So he and his team added genes that shortened the recovery time. It also increased the speed at which the plants grew. His modified plants grew up to 20 percent more than untreated ones.

In Long's study, his group used a form of genetic engineering called transgenics (转基因). It means taking genes from one plant, then putting them into another. Now they are experimenting soybeans, rice, cowpeas and cassavas.