According to a study published last week in the journal Science, scientists have found a way to change a plant’s genes (基因) in order to make it use sunlight more quickly. Someday, the results could increase the amount of food produced around the world.

By changing a plant’s genes, the scientists were able to increase leaf growth on plants by 14-20 percent. Specifically, scientists changed the plant’s protective (保护的) system. “Normally, this system is activated when a plant gets too much sunlight,” said scientist Krishna Niyogi, co-author of the study. “When the plant senses the light, it gets rid of extra energy and creates more leaves. When the plant is in the shade, the protective system is turned off. But the process is slow.”

Stephen Long is the lead author of the study. He compared a plant’s protective system to light-adjusting glasses. “When a person wears the glasses outside during the day, the lenses (镜片) darken and lighten depending on how sunny it is. Plants do the same thing,” he said. “But in plants the adjustment can take anywhere from 10 minutes to an hour. This makes it hard for plants to get the right amount of sunlight needed to create food.”

The new study sped up the process. By changing the plant’s genes, it’s more quickly than normal to turn on and turn off the protective system. As a result, leaf growth on the plants scientists used in the study increased. Leaf growth on two plants increased by 20 percent, while leaf growth on a third plant increased by 14 percent. Scientists conducted the study on tobacco plants. But they thought the genetic modification would produce the same results in corn or rice.

Dogs are capable of understanding the emotions behind an expression on a human face. The study is the latest to reveal just how connected dogs are with people. The research also provides evidence that dogs use different parts of their brains to process human emotions. By living in close contact with humans, dogs have developed specific skills that enable them to interact and communicate efficiently with people. Recent studies have shown that the dogs’ brain can pick up on emotional clues contained in a person’s voice, body smell and posture,and read their faces.

In this study,the authors watched what happened when they presented photographs of the same two adults’ faces(a man and a woman) to 26 feeding dogs. The images were placed strategically to the sides of the animals’ line of sight and the photos showed a human face ex-pressing one of the six basic human emotions: anger,fear,happiness,sadness,surprise,dis-gust or being neutral.

The dogs showed greater response and cardiac(心脏的)activity when shown photo-graphs that expressed arousing emotional states such as anger, fear and happiness. They also took longer to resume feeding after seeing these images. The dogs’ increased heart rate indicated that in these cases they experienced higher levels of stress.

In addition,dogs tended to turn their heads to the left when they saw human faces ex-pressing anger,fear or happiness. The reverse happened when the faces looked surprised, possibly because dogs view it as a non-threatening, relaxed expression.“Clearly arousing, negative emotions seem to be processed by the right side of a dog’s brain,and more positive emotions by the left side,”says Siniscalchi.

The results support that of other studies done on dogs and other mammals. These show that the right side of the brain plays a more important part in regulating the sympathetic out-flow to the heart. This is a fundamental organ for the control of the “fight or flight”Behavioral response necessary for survival.