Welcome to Learning English, a daily 30 minute program from the Voice of America.

I'm Ashley Thompson.

And I'm Mario Ritter Jr.

This program is designed for English learners,

so we speak a little slower and we use words and phrases especially written for people learning English.

Today you will hear stories from Anna Mateo and John Russell.

Later Brian Lynn presents this week's science report.

We close the show with the lesson of the day from

Andrew Smith and Jill Robbins. But first, here is Anna Mateo.

How a sperm and an egg come together has long been a mystery.

Now new research by scientists in Austria provides interesting insight.

It shows that fertilization works like a lock and key in animals that have a backbone, from fish to people.

Such animals are called vertebrates.

We discovered this mechanism that's really fundamental across all vertebrates as far as we can

tell, said co-author, Andrea Polly.

He spoke to the Associated Press

from the Research Institute of Molecular Pathology in Vienna, Austria.

The team found that three proteins in sperm

joined to form a sort of key that unlocks the egg. The process permits the

sperm to attach to the egg. The research findings come from studies in zebrafish, mice, and human cells.

They show how this process has continued over millions of years of evolution.

The findings appear in the Science magazine cell.

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