英语听力听写练习原文

英语听力听写练习原文

〈〉第一集

1.

Ocean Plastic Particles Could Get in Gills

Sea creatures eat plastic dumped in the ocean, but they also might be accumulating plastic by sucking up tiny particles with their siphons and gills. Christopher Intagliata reports.

There are now at least five major garbage patches in the world's oceans, and much of that trash is plastic. But last month researchers said they can only account for one percent of the plastic they'd expect to find in the oceans. So, where'd the rest of it go

Well, animals eat some of it. Plastic has been found in turtles, seabirds, fish, plankton, shellfish, even bottom-feeding invertebrates. But there's another way sea creatures might be accumulating plastic: by sucking up tiny plastic particles with their siphons and gills.

Researchers added common shore crabs—Carcinus maenas—to tanks of seawater containing millions of tiny plastic particles, just 10 microns in diameter. After 16 hours, all the crabs had plastic lodged in their gills. And the particles stuck around for up to three weeks, too. The results are in the journal Environmental Science and Technology. [Andrew J. R. Watts et al, Uptake and Retention of Microplastics by the Shore Crab Carcinus maenas]

The longer plastic sits in an animal, researchers say, the better the chances it will travel up the food chain. Meaning all our plastic waste could come back to bite us—or rather be bitten by us.

"Of course we eat mussels whole, without the shells. But we're potentially eating plastic, if they're from a site where there's plastic present." Lead researcher Andrew Watts, of the University of Exeter. "We don't know how much plastic we have in our stomachs… chances are we do have some."

—Christopher Intagliata

2.

Salmonella's Favorite Food Could Be Its Achilles' Heel

Salmonella's primary fuel source is the molecule fructose-asparagine. Starving it of that fuel in an infected person could kill it without harming beneficial gut bacteria. Karen Hopkin reports

Summer’s here and with it come picnic s, barbecues and of course salmonella. The germ is notorious for contaminating a variety of favorite warm-weather foods. But the bacteria’s palate is more limited than ours. Once salmonella makes its way into your system, it relies on a single unusual nutr ient to survive. That’s according to a study in the journal PLoS Pathogens. [Mohamed M. Ali et al, Fructose-Asparagine Is a Primary Nutrient during Growth of Salmonella in the Inflamed Intestine]

Most people tough it out when they get food poisoning from salmonella. That’s because treatment with antibiotics would eliminate the infection, but also get rid of the gut bacteria that promote good health.

To figure out how to target salmonella specifically, researchers screened for genes vital for the microbe’s survival during the active phase of infection. And they identified a cluster of five genes that work together to allow the bacteria to digest a molecule called fructose-asparagine. No other organisms are known to use this chemical for fuel, so starving salmonella of it could be a new strategy for fighting this foodborne bug while leaving desirable intestinal inhabitants unharmed.

Next, the researchers plan to see which foods contain large amounts of salmonella’s go-to snack. But please, don’t send unsolicited samples of Aunt Agnes’s egg salad.

—Karen Hopkin