The law of unintended consequences

When rogue Chinese scientist He Jiankui announced the birth last November of the first gene-edited babies, the scientific community warned of unforeseen consequences. He edited the twin girls’ genetics to protect them from HIV, but changing the human germline could have serious side effects, and new research is vindicating those concerns.

Babies carry two copies of each gene, one inherited from the mother and one from the father. He introduced mutations into both copies of the gene CCR5 in the baby girls during their embryonic stage of development. Researchers at the University of California, Berkeley, conducted studies that show He may have inadvertently shortened the potential lifespan not only of the infants, but also their future offspring.

People with mutations in both copies of CCR5 cannot produce a specific protein involved with a multitude of bodily functions. In the study, published online June 3 in the journal Nature Medicine, the researchers scanned the genetic health records of more than 400,000 people in a British database. They found that, although mutations in both copies of CCR5 may protect against HIV, people with the naturally occurring mutation have a 21 percent increased risk of dying young, between the ages of 41 and 78. Earlier research also showed that people with such mutations carry a four-fold increased risk of dying from influenza.

According to Xinzhu “April” Wei, a lead author of the study, scientists cannot know the full effects of modifying the human germline.

“Because one gene could affect multiple traits, and because, depending on the environment, the effects of a mutation could be quite different, I think there can be many uncertainties and unknown effects in any germline editing,” she said.

Wei also noted that some scientific evidence suggests that mutations of CCR5 may increase survival after a stroke and protect against smallpox and infection by a group of viruses that include dengue, Zika, and West Nile. But the potential for harmful, unintended effects outweighs the possibility of potential benefits.

“I think there are a lot of things that are unknown at the current stage about genes’ functions,” Wei said in a statement. “The CRISPR technology is far too dangerous to use right now for germline editing.”

But the unknown is not the only concern with gene editing. When He’s announcement first went public, Christian ethicists decried the research for a more foundational reason: It inevitably involves the destruction of other human embryos and permanently changing what God created.

Limited human endurance

Athletes push themselves ever harder to build increasing levels of endurance, but new research suggests God build a limit to that trait in the human body.

In the study, published June 5 in the journal Science Advances, scientists measured the calories burned by a group of athletes who ran six marathons a week for five months as part of the 2015 Race Across the USA, a 3,000-mile competition from California to Washington, D.C. The researchers also studied the calories expended by participants in 100-mile trail races and by pregnant women.

They found that no matter how strong and well-trained the participants were, all of them hit the same metabolic limit. Initially, the runners burned increasing amounts of calories during each race. But when their rate of energy burn reached a level 2.5 times greater than their resting metabolic rate, it plateaued for the remainder of the race. Beyond this rate, the body starts to break down its own tissues to make up for the calorie deficit.

The researchers noted that after 20 weeks of running back-to-back marathons, the athletes burned 600 calories per day fewer than expected based on their mileage, suggesting that the body can downshift metabolism to stay within sustainable levels. The researchers also found that the maximum sustainable energy expenditure among the athletes was only slightly higher than the metabolic rate sustained by pregnant women. The researchers said the finding may suggest that the same physiological limits that keep athletes from shattering speed records may also help to limit how big babies grow in the womb. —J.B.

A tarantula taco, anyone?

The Bible says John the Baptist ate locusts, a diet that may have a high yuck factor for many today. But researchers at Tufts University in Massachusetts claim that plant-fed, lab-grown insect meat, genetically modified for maximum growth, nutrition, and flavor, could offer a high volume, nutritious food alternative for a growing population.

Insect farming requires much less space, water, and energy than traditional farms. In an article published in Frontiers in Sustainable Food Systems the authors noted that scientists have even developed technology to stimulate movement of insect muscle tissue in the lab to produce a meaty texture.

Even if we came around to the idea of eating genetically modified creepy crawlies, what would they taste like? A previous article in IFL Science described the pleasant, minty flavor of termites, the salted banana flavor of water bugs, and the seafood flavors of arachnids like scorpions and tarantulas. Despite its nasty odor, the shield-shaped stink bug tastes like an apple, National Geographic reported.

Happily for meat-lovers everywhere, cultured bug meat is not yet ready for consumption.

“Research is ongoing to master two key processes: controlling development of insect cells into muscle and fat, and combining these in 3D cultures with a meat-like texture,” lead author Natalie Rubio said in a statement. —J.B.

Ebola survivors keep producing immunity

Survivors of the Ebola virus continue to produce antibodies months after recovery, according to a recent study of four people who received care at Emory University Hospital in Atlanta. The patients contracted the disease during the West Africa Ebola outbreak, which began in 2014 and killed more than 11,000 people.

Some antibodies fight infection by sticking to the virus, while others, called neutralizing antibodies, kill the virus and prevent it from replicating. The scientists discovered that during the initial infection, the four patients at Emory produced abundant antibodies that bound to the virus but no neutralizing antibodies until several months after they left the hospital.

The researchers hope their findings will assist in the development of antiviral therapies and vaccines that can provide long-lasting protection against the disease.

According to the World Health Organization, a highly effective vaccine is available for the current Ebola outbreak in the Democratic Republic of Congo and Uganda, which, as of Sunday, includes 2,062 cases and has killed 1,390 people. But some studies indicate the vaccine may provide protection for only a few months. —J.B.

‘Virgin’ anaconda gives birth

A 10-foot-long female anaconda who lives at Boston’s New England Aquarium with other female snakes produced a litter of 18 snakes earlier this year without a male, Live Science reported.

The snake, named Anna, represents one of about 30 percent of snake species that give birth to live young. Through a process called parthenogenesis (Greek for virgin birth), one of Anna’s eggs cloned itself and then self-fertilized with no sperm present. The snake delivered 18 clones of herself, all sharing DNA identical to their mother. Fifteen of the baby snakes were stillborn, and one died a few days later.

The only other documented case of anaconda parthenogenesis occurred in a British zoo in 2014. —J.B.