by Trudi Trueit
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DAVID GRUBER
Just as whales use sound to survive, other creatures use the sense of sight to their benefit. The bioluminescent jackets of the students at Explorer Academy may be fictional, but many animals, such as fireflies, jellyfish, and sharks, rely on this biochemical reaction for survival. It aids in warding off predators, attracting prey, and finding mates. Scientists and explorers, like David Gruber, are also studying how people may benefit from bioluminescence. Gruber discovered that some of the proteins found in bioluminescent creatures can be used to track cancer cells and illuminate parts of the brain to help doctors diagnose diseases. Perhaps, one day, we’ll also see bioluminescent trees naturally lighting up our roads, reducing the need to use electricity to power streetlights, or bioluminescent plants that would glow to tell farmers when they needed watering or nutrients.
To learn more about these topics and the passionate explorers who study them, check them out at the Explorer Academy website!
exploreracademy.com
BOOK 3:
THE DOUBLE HELIX
30.3285° N | 35.4444° E
Cruz took the cipher from his pocket and held it in his cupped hand. He didn’t want a security camera to get a look at it. Hunching over, he turned on the PANDA unit and pressed the blue ID button. When the screen read SCAN NOW, he slowly swept it across all three pieces of stone. A minute later, the results came up:
Item: non-foliated metamorphic limestone
Composition: calcium carbonate (CaCO3), quartz (SiO2), graphite (C), pyrite (FeS2)
Common Name: black marble
Origin: Mexico
Age: 729 million years old
Cruz’s finger hovered over the yellow button, the one that checked for DNA. His heart jumped. His mom’s DNA could still be on the cipher. He didn’t know why that scared him, but it did. It wouldn’t mean anything if it was. It wouldn’t change anything. So why was he so nervous to find out the truth? Cruz hesitated, then forced himself to push the yellow button. He waited for the go signal and slid the unit across the marble stones one more time. He heard a soft tone.
It was there! The unit had found DNA on the cipher.
What was he getting so excited about? Of course it had. Cruz had handled the stones. So had Lani, Sailor, Emmett, and Aunt Marisol. The device had probably identified all of their DNA. But what if there was more? If his mom’s DNA was on the stone, he wanted to know. He wanted to see her. But not here. Along with the security cameras, Fanchon, and Sidril, who knows who else might be lurking nearby?
Cruz knew he had 15 seconds before the unit began producing images of the life-forms the DNA belonged to. Actually, he was probably down to five seconds now. Four…three…two…
Cruz punched STOP.
Read a longer excerpt from The Double Helix at exploreracademy.com.
ACKNOWLEDGMENTS
I am blessed to have the best team in children’s publishing behind me. Thank you to Becky Baines, Erica Green, Jennifer Rees, Jennifer Emmett, Eva Absher-Schantz, Scott Plumbe, Ruth Chamblee, Caitlin Holbrook, Holly Saunders, and everyone at National Geographic who left a piece of their heart in the pages of this book. You are a class act, through and through. Thanks also to my agent, Rosemary Stimola, who nurtured my career from the beginning, always with grace and humor. I am grateful to the amazing National Geographic explorers, who inspire me each and every day. Special thanks to Gemina Garland-Lewis, Nizar Ibrahim, and Zoltan Takacs, for going the extra mile in support of this project. I am indebted to Karen Wadsworth and Tracey Daniels, for so expertly and cheerfully handling my travels and all the little emergencies that come with them (like broken shoes)! I am so appreciative of the Seattle-area independent booksellers, who allow local authors the opportunity to shine. Special thanks to Suzanne Perry from Secret Garden Books, René Kirkpatrick from University Books, and Annie Carl from the Neverending Bookshop. I am also grateful to Barbara Stolzenburg and Valerie Stein, extraordinary librarians and dear friends. To every educator who invited me to share my love of books and writing with their students—thank you! Finally, thanks to my friends and family, my husband, Bill, and especially my dad, who saw the writer in me early on and urged me to follow my dream. Because, after all, what is life without passion?
Cover illustration by Antonio Javier Caparo. Illustrations by Scott Plumbe unless otherwise noted below. All maps created by NG Maps.
1 (postcard), paladin13/iStockphoto/Getty Images; 2 (stamp), Susana Guzm/iStockphoto/Getty Images; 3 (paper), Davor Ratkovic/Shutterstock; 4 (sand), Anna Kucherova/Shutterstock; 5 (figures), Zaur Rahimoff/Shutterstock; 6 (whisk), Ingram; 7 (clothes), urfin/Shutterstock; 8 (gold), teena137/Shutterstock; 9 (den), Chris Philpotts; 10, Brian J. Skerry/National Geographic Creative; 11 (photograph), Brian J. Skerry/National Geographic Creative; 12 (photograph), Jim Richardson/National Geographic Creative; 13, Kay Dulay/Moment RF/Getty Images; 14 (photograph), Caios Campos/iStockphoto/Getty Images; 15 (photograph), Caios Campos/iStockphoto/Getty Images; 16 (photograph), Chris Burkard/Massif; 17, Barry B. Brown/National Geographic Creative; 18, Mike Parmalee/National Geographic Creative; 19, Brian J. Skerry/National Geographic Creative; 20, Brian J. Skerry/National Geographic Creative; 21, Cecilia Lewis/National Geographic Creative; 22, Eric Kruszewski/National Geographic Creative; 23, Randall Scott/National Geographic Creative; 24, Kat Keene Hogue/National Geographic Creative; 25, Cengage/National Geographic Creative; throughout (feather illustration), Oldesign/Shutterstock; throughout (abstract technology background), Rabbit_Photo/Shutterstock; throughout (abstract watercolor background), happykanppy/Shutterstock; throughout (abstract curved framework background), Digital_Art/Shutterstock