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Benoit Guenard

Scientists Decode Bedbug Genome, and It Explains Why They’re So Hard to Kill

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Benoit Guenard

You may remember when “Don’t let the bedbugs bite” was just a cute thing parents said to their children. These days, though, it’s a real—albeit futile—warning. After decades of near eradication, the bedbug is back, and badder than ever. Now scientists say they’ve found clues to the bug’s tenacity buried in its genome and microbiome. The scientists published their findings in the journal Nature Communications.

Bedbugs are living fossils; their outward appearance has hardly changed throughout their long lineage, noted corresponding author George Amato in a press statement. “But despite their static look, we know that they continue to evolve, mostly in ways that make it harder for humans to dissociate with them. This work gives us the genetic basis to explore the bedbug’s basic biology and its adaptation to dense human environments.” 

Trying to understand bedbugs (Cimex lectularius) is more than just an intellectual exercise. As anyone who’s ever dealt with an infestation knows, they’re not just gross—they’re persistent. Clearing a home of bedbugs can be a painfully drawn-out and expensive process, in part because the little pests have developed a resistance to common pesticides.

The roots of that resistance lie in the bedbug’s genome, project co-leader Coby Schal said in a press statement. “The genome sequence shows genes that encode enzymes and other proteins that the bedbug can use to fight insecticides, whether by degrading them or by preventing them from penetrating its body."

And that’s not all they found. In teasing out the bedbug’s genetic code, the researchers saw explanations for many of the pest’s unique traits, like sex shielding. Male bedbugs are notoriously opportunistic about sex. They’ll jab their sharp, penis-like appendages at pretty much anything, including other males. And the sex itself isn’t pretty: The male bedbug stabs the female in the abdomen, then releases his sperm freely into the wound. To ease the sting of what scientists call “traumatic insemination,” female bedbugs have developed a kind of shielded funnel on their undersides. The protein that keeps that shield strong is called resilin, and it has its own code in the bedbug’s genome.

Not all the bedbug’s genes are bedbug genes; some of them came from other organisms, including the parasitic bacterium Wolbachia. "We don't know if the bacterium is co-opting the bedbug or if the bedbug is co-opting the bacterium,” Schal said in the press statement. “Very few of these bacterial genes are functional and we don't know what proteins they are producing. But it would be fascinating if bacterial genes that are useful to the bedbug, such as those involved in B vitamin metabolism, were incorporated into the bedbug genome."

The bug's microbiome had its own insights to offer. Researchers found the genes of more than 400 species of bacteria living on and in the bugs. The scientists theorize that these microbes help keep the bedbugs alive—which means there's a chance that targeted antibiotics to knock out these bacteria could eventually help us knock out the bedbugs, too.

Another finding concerns the bedbugs' ability to take in relatively large amounts of liquid (that is, blood) without exploding. They can balloon up to 200 percent their body size while feeding through a handy diuretic system. "Bedbugs must be able to shed that water while retaining the blood's nutrients," Schal said.

And then there’s the bedbug’s bite. The scientists found proteins that act as both anesthetics and anticoagulants that keep your blood flowing while keeping you from noticing.


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Scientists Remove Disease-Causing Mutations from Human Embryos
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Researchers have successfully edited the genes of viable human embryos to repair mutations that cause a dangerous heart condition. The team published their controversial research in the journal Nature.

The versatile gene-editing technique known as CRISPR-Cas9 is no stranger to headlines. Scientists have already used it to breed tiny pigs, detect disease, and even embed GIFs in bacteria. As our understanding of the process grows more advanced and sophisticated, many researchers have wondered how it could be applied to human beings.

For the new study, an international team of researchers fertilized healthy human eggs with sperm from men with a disease called hypertrophic cardiomyopathy, a condition that can lead to sudden death in young people. The mutation responsible for the disease affects a gene called MYBPC3. It’s a dominant mutation, which means that an embryo only needs one bad copy of the gene to develop the disease.

Or, considered another way, this means that scientists could theoretically remove the disease by fixing that one bad copy.

Eighteen hours after fertilizing the eggs, the researchers went back in and used CRISPR-Cas9 to snip out mutated MYBPC3 genes in some of the embryos and replace them with healthy copies. Three days later, they checked back in to see how their subjects—which were, at this point, still microscopic balls of cells—had fared.

The treatment seemed successful. Compared to subjects in the control group, a significant number of edited embryos appeared mutation- and disease-free. The researchers also found no evidence that their intervention had led to any unwanted new mutations, although it is possible that the mutations were there and overlooked.

Our ability to edit human genes is improving by the day. But, many ethicists argue, just because we can do it doesn’t mean that we should. The United States currently prohibits germline editing of human embryos by government-funded researchers. But there’s no law against such experimentation in privately funded projects like this one.

The same day the new study was published, an international committee of genetics experts issued a consensus statement advising against editing any embryo intended for implantation (pregnancy and birth).

"While germline genome editing could theoretically be used to prevent a child being born with a genetic disease, its potential use also raises a multitude of scientific, ethical, and policy questions,” Derek T. Scholes of the American Society of Human Genetics said in a statement. “These questions cannot all be answered by scientists alone, but also need to be debated by society."

Ethicists and sociologists are concerned by the slippery slope of trying to build a better human. Many people with chronic illness and disability live happy, complete lives and report that they’re limited more by discrimination than by any medical issues.

Disability studies expert Lennard Davis of the University of Illinois says we can’t separate scientific decisions from our society’s history of violence against, and oppression of, disabled and sick people.

“A lot of this terrific science and technology has to take into account that the assumption of what life is like for people who are different is based on prejudice against disability,” he told Nature in 2016.

Rosemary Garland-Thomson is co-director of the Disability Studies Initiative at Emory University. Speaking to Nature, she said we are at a cultural and ethical precipice: “At our peril, we are right now trying to decide what ways of being in the world ought to be eliminated.”

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Naonobu Noda/NARO
Japanese Scientists Engineer 'True Blue' Chrysanthemums
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Naonobu Noda/NARO

The land of the square watermelon has done it again: Japanese scientists have created the world's first blue chrysanthemums. They described their process and results in the journal Science Advances.

Nature doesn't make a whole lot of blue things. Out of the 280,000 species of flowering plants on Earth, less than 10 percent make blue flowers. But these are hipster flowers, flying low under the public radar. There's no real market for them. Blue roses, carnations, lilies, or chrysanthemums, though: now those are products florists could take to the bank.

Or they could, if scientists could get them to work. Flower experts have been trying to breed blue flowers for centuries, to no avail. The horticultural societies of Britain and Belgium even put up a cash prize in the 1800s for the first person to breed a true blue rose. Nobody won.

But bioengineering is a lot more sophisticated than it used to be. Today's plant experts can tinker with an organism's genetic code to coax it into doing things nature never intended it to do. By 2005, scientists sponsored by the Japanese company Suntory had that blue rose—although "blue" may be a generous term.

Next up for researchers was the chrysanthemum, a species that may be even more significant than the rose in Japan. Chrysanthemums are everywhere there, appearing on coins, passports, clothing, and art. They symbolize autumn, but also the monarchy, the imperial throne, and the nation of Japan itself. Making a blue mum would be a huge cultural achievement (not to mention a potential goldmine).

Researchers from Suntory and Japan's National Agriculture and Food Research Organization decided to swipe a few tricks from two preexisting blue flower species, Canterbury bells and the butterfly pea. Both species owe their color to pigments called anthocyanins. These pigments appear in chrysanthemums, too, but a slightly different molecular structure means that they make red and purple petals, not blue ones.

By swiping multiple genes from the two blue species and adding them to the mum's genetic blueprint, the scientists were able to reshape the chrysanthemum anthocyanins to make what botanists call "true blue."

Blue color swatches among blue chrysanthemum flowers.
Naonobu Noda / NARO

Once again, "blue" may be a generous term.

"Their flowers are like a cool lavender at best," artist and biohacker Sebastian Cocioba, who is trying to genetically engineer a blue rose, told Gizmodo. "I could never feel comfortable calling that blue."

The researchers acknowledge that they've got more work to do, and say they have ideas for how to create a bluer flower. "However," lead author Naonobu Noda noted to Gizmodo, "as there is no [single] gene to realize it, it may be difficult."


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