Outwitting a deadly tick-borne virus

Powassan virus is a rare tick-borne infection that is becoming more widespread in the northern U.S. It can cause fever, nausea, and headaches, or even lead to brainswelling and potentially be fatal. This dangerous virus can only be studied in high-security labs.

A team led by Susan Hafenstein, a professor in the College of Biological Sciences, with doctoral student and lead author Sayan Das, wanted to study the Powassan virus under safer conditions. Along with members from the Huck Institutes of the Life Sciences at the Pennsylvania State University and the U.S. Department of Agriculture, the team “hacked” the virus, swapping parts of it with a yellow fever virus vaccine strain, which is much safer to handle.

Examining the doppelgänger (also known as a chimeric virus), the team was able to visualize the virus at the atomic level for the first time. They observed three hidden lipid pockets inside of the virus, and when they mutated a single amino acid residue (Trp467) interacting with this pocket, the virus fell apart and could not reassemble. This could be used to develop vaccines and treatments.

“Basically, we made a lookalike version of Powassan virus ... [that] is safe to handle in less secure labs,” says Das. “Think of it like building a movie prop of a dangerous animal where you get the full appearance and behavior of the animal, but without the bite.”

The study was published in Science Advances in July.

How powerboats affect marine life

Large surface waves produced by powerboats are a mainstay for recreational watersports. A new study from the U of M shows that beneath the surface, factors such as propeller thrust and other types of waves can impact delicate lake bed ecosystems.

Researchers at the University’s St. Anthony Falls Laboratory built on previous research to study the effects of powerboats on lake ecosystems over 2022 and 2023. They placed acoustic-based sensors that measured pressure and velocities through the water column and at the lake bottom at two different locations and two different depths. They also collected sediment samples and data on various water quality parameters.

The researchers tested seven recreational powerboats commonly used in Minnesota’s lakes and rivers based on their two most-used settings. They found all powerboats produce water currents and turbulence that can disturb the lakebed, and more powerful turbulence from wakeboats can directly resuspend sediments in the water. This can foster release of nutrients like phosphorus from sediment that can stimulate excessive algae growth.

Researchers say all powerboats, when leisurely cruising or planing, should operate in 10 feet of water or greater to minimize impacts caused by motions generated by a boat’s hull—and during surfing, wakeboats should operate in depths of 20 feet or greater. “For all motorized boats, simply being careful about where you steer your boat and avoiding shallow spots can make a huge difference,” said Jeff Marr, coauthor of the study and associate director of engineering and facilities at the St. Anthony Falls Lab in the College of Science and Engineering.

The study was published in July in the U of M University Digital Conservancy.

Helping farmers manage nitrogen

Farmers often face tough decisions about how much nitrogen to apply to corn, especially when spring weather disrupts pre-plant fertilizer plans. Too little can limit crop yield and reduce profits, while too much reduces economic returns on the fertilizer and can lead to environmental degradation.

New U of M research improves a tool farmers can use to guide these decisions. The Pre-Sidedress Nitrate Test (PSNT) uses soil nitrate status to help farmers determine whether their corn crop may need more nitrogen.

Researchers found that 20 parts per million of nitrate in the top 12 inches of soil, measured when corn has four to six fully expanded leaves, reliably delivers 97 percent of maximum yield. Spring precipitation also influences PSNT values: The threshold was higher in dry years at 21.5 parts per million and lower in wet years at 17.4 parts per million. PSNT is especially useful when wet conditions compromise pre-plant nitrogen applications or when a substantial amount of residual nitrogen is suspected.

“Nitrogen decisions are always a moving target, especially when spring weather doesn’t cooperate,” says lead author Emerson Souza, a researcher in the College of Food, Agricultural and Natural Resource Sciences. “The PSNT gives farmers a way to read the field’s nitrogen status in real time, rather than guessing, and allows us to adjust quickly when the soil is coming up short.”

The research was published in June in the Soil Science Society of America Journal.

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