Do Mosquitoes Love You? It Could Be Genetic

Image Credit: Fernández-Grandon et al., PLOS ONE

When it comes to choosing a meal, mosquitoes may see some people as a bland bowl of whole grain cereal, while a select number of unlucky folks stand out like a giant, cheese-oozing pizza. The difference is in how you smell: Certain body odors are just more attractive to a mosquito on the prowl. But research published in PLOS ONE in 2015 suggests that your likelihood of getting bitten by a mosquito could be yet another thing you can blame on your parents: Your attractiveness to mosquitoes might be genetic.

To determine whether mosquito attraction might have a genetic component, researchers from the London School of Hygiene and Tropical Medicine studied the appeal of 18 identical and 19 fraternal twins (as a control mechanism, all were post-menopausal women, which the researchers said would "eliminate the variation introduced by sex or phase of menstruation") to female Aedes aegypti mosquitos, the species that carries the viruses for yellow fever and Dengue. To do so, the participants stuck their arms in a lab device called a “Y-tube olfactometer,” which allows the mosquito to choose between two divergent paths leading to the tasty hand of a human test subject. 

Image Credit: Fernández-Grandon et al., PLOS ONE

Identical twins (who come from the same egg and are more genetically similar than non-identical twins) proved to be more similar in their rates of attractiveness to the mosquitos than fraternal twins, suggesting that there may be a genetic underpinning to the body odors that attract or repel biting insects. 

Granted, the results of this pilot study aren’t quite powerful enough to make a definitive case for a mosquito-bite inheritance. And your parents wouldn’t be solely responsible for your itching: Studies suggest that pregnancy, body mass, and even beer consumption may also make people more attractive to certain species of mosquitos.

Twins using the Y-tube olfactometer. Image Courtesy London School of Hygiene and Tropical Medicine

But the idea is, if we can pin down the genetic aspects of mosquito attraction, we may also be able to find new ways to prevent mosquito bites. Aside from the obvious annoyance of constant itching, mosquitos spread deadly diseases (by some estimates, the mosquito is the most deadly animal on Earth). If there really is a genetic component to our susceptibility to mosquito bites, we could better tailor mosquito repellents to individual differences. 

“In the future we may even be able to take a pill which will enhance the production of natural repellents by the body and ultimately replace skin lotions,” senior author James Logan suggested in a press release.

[h/t: Eurekalert]

Courtesy of Nature
Scientists Create Three Puppy Clones of 'Snuppy,' the World's First Cloned Dog
Courtesy of Nature
Courtesy of Nature

Snuppy, the world's first cloned dog, died in 2015, but his genetic legacy lives on. As the National Post reports, South Korean scientists recently described in the journal Scientific Reports the birth of three clone puppies, all of which are identical replicas of the famous Afghan hound.

Those who lived through the 1990s might remember Dolly, the Scottish sheep that gained fame for being the very first mammal to be cloned from an adult cell. Following Dolly's 1996 cloning, scientists managed to replicate other animals, including cats, mice, cows, and horses. But dog cloning initially stymied scientists, Time reports, as their breeding period is limited and their eggs are also hard to extract.

Ultimately, researchers ended up using somatic cell nuclear transfer (SCNT) to clone a dog, the same method that was used to make Dolly. In the early 2000s, a team of South Korean scientists inserted DNA harvested from an Afghan hound's skin cells into a dog egg from which the DNA had been removed. The egg divided, which produced multiple cloned embryos.

The scientists implanted 1095 of these embryos in 123 dogs, an exhaustive initiative that yielded just three pregnancies, according to NPR. Of these, Snuppy—whose name is a combination of "puppy" and Seoul National University's initials—was the only survivor.

Snuppy died from cancer in April 2015, just shortly after his 10th birthday. To celebrate his successful life, the same South Korean researchers decided to re-clone him using mesenchymal stem cells from the dog's belly fat, which were taken when he was five. This time around, they transferred 94 reconstructed embryos to seven dogs. Four clones were later born, although one ended up dying shortly after birth.

The tiny Snuppy clones are now more than a year old, and researchers say that they don't think that the pups face the risk of accelerated aging, nor are they more disease-prone than other dogs. (Dolly died when she was just six years old, while cloned mice have also experienced shorter lifespans.) Snuppy's somatic cell donor, Tai, lived just two years longer than Snuppy, dying at age 12, the average lifespan of an Afghan hound.

Researchers say that this new generation of Snuppys will yield new insights into the health and longevity of cloned animals. Meanwhile, in other animal cloning news, a Texas-based company called ViaGen Pets is now offering to clone people's beloved pets, according to CBS Pittsburgh—a service that costs a cool $50,000 for dogs.

[h/t National Post]

Researchers Pinpoint the Genes Behind the Durian's Foul Stench

Durian is a popular fruit in parts of southeast Asia. It's also known for having the most putrid, off-putting odor of any item sold in the produce section. Even fans of durian know why the fruit gets a bad rap, but what exactly causes its divisive scent is less obvious. Determined to find the answer, a team of researchers funded by "a group of anonymous durian lovers" mapped the fruit's genome, as reported by the BBC.

The study, published in the journal Nature Genetics [PDF], contains data from the first-ever complete genetic mapping of a durian fruit. It confirms that durian's excess stinkiness comes from sulfur, a chemical element whose scent is often compared to that of rotten eggs.

Analysis of the fruit's chemical makeup has been done in the past, so the idea that sulfur is a major contributor to its signature smell is nothing new. What is new is the identification of the specific class of sulfur-producing genes. These genes pump out sulfur at a "turbocharged" rate, which explains why the stench is powerful enough to have durian banned in some public areas. It may seem like the smell is a defense mechanism to ward off predators, but the study authors write that it's meant to have the opposite effect. According to the paper, "it is possible that linking odor and ripening may provide an evolutionary advantage for durian in facilitating fruit dispersal." In other words, the scent attracts hungry primates that help spread the seeds of ripe durian fruits by consuming them.

The revelation opens the door to genetically modified durian that are tweaked to produce less sulfur and therefore have a milder taste and smell. But such a product would likely inspire outrage from the food's passionate fans. While the flavor profile has been compared to rotten garbage and dead animal meat, it's also been praised for its "overtones of hazelnut, apricot, caramelized banana, and egg custard" by those who appreciate its unique character.

[h/t BBC]


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