Readers weigh in on deer-vehicle collisions, mouse sperm in space and more

Neuroscience mysteries

A three-dimensional look at 50,000 brain cells taken from a woman with epilepsy uncovered some pairs with an astonishingly large number of connections, Laura Sanders reported in “An intricate brain map reveals quirks” (SN: 7/3/21 & 7/17/21, p. 6).

Given that nerve cells usually touch once, reader Leilani wondered if the woman’s epilepsy could be the reason for the cells’ multiple connections.

The researchers don’t think epilepsy is responsible for this cellular quirk, Sanders says, but for now, we can’t be sure. “The tissue that scientists used to reconstruct the map was thought to be healthy, normal tissue that was removed to allow access to the spot in the woman’s brain where seizures started. But it’s possible that abnormal neural activity influenced the cells in that supposedly healthy tissue too,” she says. “Until scientists have more maps that are made from a wider variety of brains, we won’t know how common any of these ‘rare’ findings actually are.”

Frankly, my deer, I don’t give a slam

Gray wolves in Wisconsin that use roads as travel corridors may scare deer away, reducing deer-vehicle collisions, Jack J. Lee reported in “Gray wolves clear deer from roadways” (SN: 7/3/21 & 7/17/21, p. 8).

Reader John Hosack asked if this wolf behavior leads to increased wolf-vehicle collisions.

Wolf-vehicle collisions occur, Lee says, but less frequently than deer-vehicle collisions do. According to the Wisconsin Gray Wolf Monitoring Report, there were 21 wolf-vehicle collisions in the state from April 2019 to April 2020. That number is much lower than the nearly 20,000 deer-vehicle collisions that occur in the state each year. Gray wolves’ small population size likely contributes to the low numbers, Lee says. But wolves may also tend to avoid roads with heavy traffic. A study in the April 2020 Mammalian Biology found that wolves in Poland prefer to travel along high-traffic forest roads when there was low human activity.

Bound by biology

HIV’s ability to create myriad variants in a single person partly explains why scientists haven’t been able to find an effective vaccine, Erin Garcia de Jesús reported in “Why HIV vaccines remain elusive” (SN: 7/3/21 & 7/17/21, p. 14).

Given this high rate of mutation, reader Art Hager wanted to know why HIV hasn’t found ways to spread through the air or through mosquitoes.

Even HIV has its limits, Garcia de Jesús says. The virus doesn’t last long outside the body, and the changes it would have to undergo to spread in alternative ways would likely be more trouble than they’re worth and wouldn’t happen in real life, she says. “Let’s pretend that HIV is a small animal living on a mountain. This animal wants to get from peak A to peak B, but the valley in between is filled with wolves. The creature looks to peak C, but that valley has a lake that is impossible to cross. So it might as well stay on peak A where there’s plenty of food and space, even if there are a few hawks flying around.”

What gives, eggsactly?

An experiment on the International Space Station suggests that space radiation doesn’t affect the viability of sperm, Maria Temming reported in “After spending years in space, mouse sperm produce healthy pups” (SN: 7/3/21 & 7/17/21, p. 16).

Reader Suzan Chastain wondered whether eggs are similarly unaffected by space radiation.

More research is needed to understand how eggs fare in space, says biologist Teruhiko Wakayama of the University of Yamanashi in Kōfu, Japan. Long-term experiments with mouse eggs are challenging because, unlike freeze-dried sperm, the eggs must be stored at temperatures of about –196° Celsius and the freezers on the International Space Station don’t get that cold, Wakayama says. His team next plans to do a short-term experiment on the space station that will investigate microgravity’s effects on developing mouse embryos. The embryos will be stored for one to two weeks in freezers at –95° C.