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Lions and Tigers and Phages, Oh My!
  
By Kate Dalke

Most people visit the Bronx Zoo for the animals, but William Jacobs goes for the phages.

The zoo is a favorite stomping ground for Jacobs, who studies phages at the Albert Einstein College of Medicine in New York City. Phages are viruses that infect bacteria and they’re found pretty much everywhere bacteria are—in dirt, seawater, and the monkey pit.


Colorized image of corn dog phages.

Now scientists have sequenced ten new phage genomes, including two unearthed at the Bronx Zoo. Some of the phages can infect bacteria that cause infectious diseases such as tuberculosis and leprosy.

The most striking aspect of the new genomes is their incredible diversity. The phages share only half their genes with one another, and nearly 90 percent of their genes don’t match genes found in other sequenced organisms.

“Bacteriophages are the most abundant organisms, yet we know extremely little about what’s out there,” says Graham F. Hatfull of the University of Pittsburgh, who led the project.

“It’s become clear that you have to look at the genomes if you want to learn about phage diversity and how they’ve evolved,” he adds.

It appears that these phages have creative ways of evolving and exchanging new genes among themselves, and they seem to carry bacterial genes. Another surprise was the discovery that phage genes may contribute to the infectiousness of host bacteria.


Phages isolated from Latrobe, Pennsylvania, and the Bronx Zoo near the Zebra House. View full

Besides Jacobs, the other phage-hunters in the project included high-school students from Latrobe, Pennsylvania, and Pelham, New York. The students helped isolate the new phages as part of class taught by Jacobs’ sister.

Scientists at the Tuberculosis Research Center in Chennai, India, also isolated some of the sequenced phages from soil outside the clinic.

Everyone named the phages they isolated. One student, Jacob Falbo, was so inspired by the experience that he registered the email address Phagehunter@aol.com.

Each summer, Jacobs takes a new group of students to the Bronx Zoo to isolate phages. The soil there is full of bacteria. “When we visit the zoo, I can just smell the phages,” he says.

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Pedulla, M.L. et al. Origins of highly mosaic mycobacteriophage genomes. Cell 113, 171-182 (April 18, 2003).
 

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