As home gardeners in the US page through seed catalogs (目录册) and pick out their favorite plants this week, there's a new seed that has never been available to them before: a purple tomato. It is the first genetically engineered food crop to be directly marketed to home gardeners and the seeds went on sale Saturday.

The lending scientist behind the tomato is Cathie Martin. About 20 years ago, she set out to create a transgenic (转基因的) tomato, using DNA from a purple snapdragon, which is an unrelated eatable flower. Her goal was to develop a tomato with high levels of anthocyanins, chemicals that give blueberries, blackberries, eggplant and purple cabbage their color. Research has shown that anthocyanins also have anti-cancer and anti-aging effects.

"It's normal for tomatoes to make these healthy chemicals. But they typically don't make them very much in the fruit," Martin told reporters in an interview. "They normally appear in the leaves and stems."

So she started with, separating the DNA in the snapdragon flower that turns on and off the purple color. Next, she used a basic technique that was figured out by scientists in the 1980s to introduce it into a certain bacteria so that the tomato could then take in the foreign genetic material and express this new gene.

The result? In a paper published in Nature, Martin found that the purple tomato had, per weight, as much anthocyanin as a blueberry or eggplant, and that the mice who ate a diet mixed with purple tomatoes lived 30% longer than those who didn't.

"Americans eat more tomatoes annually, so it makes the nutritional benefits more accessible," Martin said.

Of course, some people have raised health concerns about eating genetically engineered foods. But these foods were introduced three decades ago and studies have not shown any harm.

"The purple potato is another great example of how the outcomes and applications of such biotechnologies can improve our life," Martin said.

Yu Zeling, an award-winning master of paper cutting, fills her studio with cutouts of anımals, people, and scenes that are so vivid that they seem to leap from the walls. Her art covers village life in Ansai, a rural district in Shaanxi Province.

Ms. Yu came to paper cutting in the late 1970s as naturally as she breathed the earthy air. "We were very poor, and when it was time to celebrate the New Year, we all put paper-cuts on the windows to decorate our houses," she says, recalling the holiday at her childhood home. Ms. Yu and others are working to keep the folk art alive, even as it evolves away from its roots as adornment for farmhouses.

The art originated in China in the centuries after paper was invented in A. D. 105. Full of auspıcıous（吉利的）symbols from daily life, the decorations represented good weather, many offspring, long life, wealth, and happiness.

Using newspaper, Ms. Yu first practiced cutting the image of a Chinese national flag that she saw in a school textbook. She cut it 100 times before she was satisfied. Then her aunt took over, introducing her to increasingly complicated traditıonal themes.

Ms. Yu was later invited to train in the Ansai's Cultural Center. After years of training, Ms. Yu became a master in her own right, wınning one award after another. Her works are on display ın museums. But she's humble about her achievements. "I was, and still am, a farmer," she says with a smile.

Hoping to carry on and grow the folk art, Ms. Yu volunteers to teach at free community training sessions. Paper cutting is also taught in Ansai's public schools. Ms. Yu is aware of the need to go beyond protecting traditions and embrace new paper-cut experiments.

A study of Australian teens' Instagram (a popular photo social media platform) usage found 57% of Australian teenagers use it, while 30% reported being contacted by a stranger, and 20% reported being sent inappropriate unwanted content.

Facebook is considering launching a version of Instagram for children under the age of 13 to safely use it. Currently the company does not allow people who are under 13 to create an account on the platform. A spokesperson for Facebook, announced the company was exploring a parent-controlled version, similar to the Messenger Kids app that is for kids between 6 and 12.

"Increasingly kids are asking their parents if they can join apps that help them keep up with their friends. Right now there aren't many options for parents, so we're working on building additional products that are suitable for kids, managed by parents," the spokesperson said. "We're exploring bringing a parent-controlled experience to Instagram to help kids keep up with their friends, discover new hobbies and interests, and more."

In a blog post, the company noted that although people were asked to enter their ages when signing up for Instagram, there was nothing to prevent them from lying about their ages at registration. Facebook said it would overcome that by using machine learning in association with the registration age to determine people's ages on the platform.

The company also announced plans to roll out new safety features, including preventing adults from messaging children under 13, sending safety notices to children when they are messaged by an adult who sends a lot of friend requests, and making it more difficult for adults to find and follow children using the search function in Instagram. Children will also be encouraged to keep their profiles private at the point of registration.