Scientists prize plant, animal genomes
New York – Just about every week, it seems, scientists publish the unique DNA code of some creature or plant. Just in February, they published the genome for the strawberry, the paper mulberry tree, the great white shark and the Antarctic blackfin icefish.
They also announced that, thanks to a crowdfunding campaign, they’d produced the genome of Lil BUB, a female cat with a large internet following.
That followed a notable advance in January: an improved genome for the axolotl, a salamander renowned for regrowing severed limbs and other body parts.
Scientists have been uncovering genomes for quite a while. The first from an animal – a worm – came in 1998. Now, the technology has advanced far enough that scientists last year announced a project to produce the genomes for all life forms on Earth other than bacteria and single-celled organisms.
But what’s the point of uncovering new genomes?
For scientists, a detailed look under the hood of their favorite organism provides a foothold for learning the deepest secrets of their objects of attention, it leads to discoveries about how life works, and possibly how to prevent disease.
Take the mosquito. Late last year, researchers published a much-improved description of the DNA code for a particularly dangerous species of mosquito: Aedes aegypti, notorious for spreading Zika, dengue and yellow fever.
That achievement came from analyzing the DNA of 80 mosquito brothers. They were born in Leslie Vosshall’s lab at Rockefeller University in New York, where thousands of mosquitoes swarmed in cages recently as Krithika Venkataraman was trying to make some more.
She stuck a tube that protruded from her mouth like a straw into a transparent cube filled with male mosquitoes. Then she repeatedly sucked about 30 males at a time into the tube. She counted them, and then blew them into another cube that housed females. Before long, the two sexes were mating.
You can think of a genome as an instruction book for building a living thing. Its language is a four-letter alphabet, which stand for the four compounds that make up the innards of the DNA molecule. The order of those compounds along the molecule is the code; it creates “words” that we call genes.
The mosquito genome, for example, is about 1.28 billion letters long, a bit less than half the length of the human version. Knowing the DNA sequence lets scientists manipulate it with gene editing techniques, said Ben Matthews of the Vosshall lab, who was part of the international team that published the refined description of the mosquito genome last November.
And once researchers started analyzing that version of the DNA code, discoveries began to pop out.
■They nearly doubled the known size of a family of genes that help mosquitoes sense information from their environment, such as the odor of humans. That was “totally, mind-blowingly, unexpected,” Vosshall said.
Further study may reveal surprises about what mosquitoes pay attention to, Vosshall said. And that could lead to better lures for mosquito traps, as well as better repellents. Maybe scientists can find something “10,000 times more disgusting” to a mosquito than the old standby, DEET, she said.
■They found new details about genes that let some mosquitoes resist certain insecticides. That’s a possible step toward predicting what insecticides would be useless for fighting certain populations, as well as a potential lead for coming up with new chemical weapons against the insect.
■ They found previously unknown targets for a major class of insecticides. That could open the door to designing new versions that target mosquitoes while sparing beneficial insects and posing less risk to people.
■They narrowed the search for genetic variants that prevent some Aedes aegypti mosquitoes from infecting people with dengue, a severe flu-like illness that sickens millions every year. If those variants can be identified, scientists might use genetic engineering to reproduce them in some mosquitoes, which could then be released to spread the variants though wild populations, Vosshall said.
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