“Thirty years ago, people noticed that these asteroid starfish larvae could clone themselves, and they wondered what the adult form was,” said staff scientist Rachel Collin at the Smithsonian Tropical Research Institute (STRI). “They assumed that because the larvae were in the Caribbean the adults must also be from the Caribbean.”

Scientists monitor larvae because the larvae can be more sensitive to physical conditions than the adults and larval dispersal has a large influence on the distribution of adult fishes and invertebrates. Collin’s team uses a technique called DNA barcoding to identify plankton. They determine the DNA sequence of an organism, then look for matches with a sequence from a known animal in a database.

“This mystery species was one of the most common in our samples from the Caribbean coast of Panama,” Collin said. “We knew from people’s studies that the DNA matched sequences from similar larvae across the Caribbean and it matched unidentified juvenile starfish caught in the Gulf of Mexico — but no one had found a match to any known adult organism in the Caribbean. So we decided to see if the DNA matched anything in the global ‘Barcode of Life’ data base.”

“That’s when we got a match with Valvaster striatus, a starfish that was thought to be found only in the Indo West Pacific,” Collin said. “The is the first-ever report of this species in the Atlantic Ocean. We could not have identifed it if Gustav Paulay from the University of Florida didn’t have DNA sequences from invertebrates on the other side of the world.”

But why are the larvae common in the Caribbean if adult Valvaster starfish have never been found here? Are the adult starfish hidden inside Caribbean reefs, or are the larvae arriving from the other side of the world?

V. striatus is widespread but rare in the western Pacific. The few reports from collectors and the confirmed photos on iNaturalist range from the Indian Ocean to Guam and Hawaii. These starfish live deep in the reef matrix, only coming out at night. So, it is possible that there are adults in the Caribbean that have never been seen. But the other possibility, that the ability to clone themselves may allow them to spread around the world, is also intriguing.

“It’s possible that the ability of the larvae to clone themselves is not just a clever way to stay forever young,” Collin said. “There’s a natural barrier that keeps organisms from the western Pacific and the Indian ocean from crossing the Atlantic to the Caribbean. After they make it around the tip of Africa, they are met by a cold current that presumably kills tropical species.”

“Just how cloning could help them get through the barrier is still not known, but it’s intriguing that another sea star species from the Indo West Pacific that was collected for the first time in the Caribbean in the 1980s also has cloning larvae,” Collin said.

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Materials provided by Smithsonian Tropical Research Institute. Note: Content may be edited for style and length.

One strategy is to replace artificial surfaces with vegetation cover. In water-limited regions such as Utah, a state with one of the lowest annual rainfall rates in the United States, municipalities have to balance the benefit of cooler temperatures with using precious water for irrigation.

A new University of Utah study will make those decisions easier for the semi-arid Salt Lake Valley, the largest metropolitan area in Utah located in the northern part of the state. The researchers used 60 sensors to analyze the microclimate in five locations throughout the valley. They found that neighborhoods dominated by impervious surfaces were warmer and drier than the urban parks — up to 2 degrees warmer in both the daytime and nighttime.

“It’s intuitive — we’ve all stood in a parking lot on a hot summer day, and you feel the heat from the ground. And when you’re standing on a lawn, it’s cooler,” said lead author Carolina Gomez-Navarro, postdoctoral researcher at the U. “But we need to back up intuition with data to determine the best strategy for our semi-arid cities.”

Gomez-Navarro and the team measured the temperature and humidity inside five parks and in their adjacent residential areas from June through August in 2016. They also analyzed how the surrounding landscape impacted air temperature. Surprisingly, they found that lawns reduced daytime and nighttime temperatures even more than trees did. While trees provide shade, lawns and turfgrass act like a swamp cooler — water moves through the plant, evaporating from tiny holes in the leaves and cooling the air.

Much of the heat that builds up during the day dissipates at night. The more open the land, the better heat can escape into the atmosphere. An area with many trees acts like a greenhouse, trapping heat close to the ground. The study concluded that a mixture of dispersed trees and grass is the most effective way to cool temperatures in the Salt Lake Valley.

“Understanding how ground cover impacts temperature is crucial for city planners to weigh the benefits and costs of its landscape design,” said Gomez-Navarro. “This land used to be a valley of bushes and bare soil. Any vegetation we add is going to need lots of irrigation and modify the landscape in many ways.”

The paper was published on October 13, 2020 in the journal Agricultural and Forest Meteorology.

Is the grass always greener?

Gomez-Navarro focused on five parks and the adjacent neighborhoods throughout the Salt Lake Valley: Hunter (northwest), Lone Peak (southeast), Midvale City (south central), Southridge (northwest) and Sugar House (northeast). Each location had 12 sensors that measured temperature and humidity: six within the park and six in the residential areas. Gomez-Navarro analyzed ground cover in a 10-meter diameter around each sensor using satellite images to estimate the percentage of the roofs, pavement, trees or turfgrass. She found that the more turfgrass in a given area, the lower the temperature.

She analyzed canopy cover by taking photos of the sky above each sensor with a fish eye lens. She used software that calculated the area that trees obstructed the sky. She found that the more open the landscape, the hotter the daytime temperature. The more canopy cover, the more shade reduced temperature.

The authors expected there to be temperature and humidity differences between the parks and neighborhoods. They were surprised, however, that turfgrass had nearly the same impact on air temperature as trees. It seems counterintuitive because of the difference between air temperature and perceived temperature. Perceived temperature is how humans feel the environment. Wind, air temperature, humidity and solar radiation all factor into how comfortable we are.

“We didn’t measure human comfort in this study, but we know that the amount of solar radiation on our skin has a big impact on the perceived temperature,” said Gomez-Navarro. “Even if the air temperature is the same, we feel much cooler under the shade of a tree because it blocks some of the radiation.”

Smart city planning

Next, Gomez-Navarro will study how different landscapes directly affect how humans feel comfortable in their environment, and how plant cover type affect soil water loss.

“It’s going to keep getting hotter and parks can be a refuge from the heat. But exactly how many degrees can they cool the air? And what should we plant to maximize this cooling?” said co-author Diane Pataki, professor of biology at the U. “It’s getting easier and cheaper to measure temperature all over parks and neighborhoods, and we’re going to need this information to make good decisions about future park designs.”

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Materials provided by University of Utah. Original written by Lisa Potter. Note: Content may be edited for style and length.

Temporal lobe epileptic seizures are debilitating and can cause lasting damage in patients, including neuronal death and loss of neuron function.

Sanjay Kumar, an associate professor in the College of Medicine’s Department of Biomedical Sciences, and his team are paving the way toward finding effective therapies for this disease.

The research team found a mechanism in the brain responsible for triggering epileptic seizures. Their research indicates that an amino acid known as D-serine could work with the mechanism to help prevent epileptic seizures, thereby also preventing the death of neural cells that accompanies them.

The team’s findings were published in the journal Nature Communications.

The temporal lobe processes sensory information and creates memories, comprehends language and controls emotions. Temporal lobe epilepsy (TLE) is the most common form of epilepsy in adults and is not improved with current anti-epileptic medications.

“A hallmark of TLE is the loss of a vulnerable population of neurons in a particular brain region called the entorhinal area,” Kumar said. “We’re trying to understand why neurons die in this brain region in the first place. From there, is there anything that we can do to stop these neurons from dying? It’s a very fundamental question.”

To help further understand TLE pathophysiology, the Kumar lab studies underlying receptors in the brain. Receptors are proteins located in the gaps, or junctions, between two or more communicating neurons. They convert signals between the neurons, aiding in their communication.

Kumar and his team discovered a new type of receptor that they informally named the “FSU receptor” in the entorhinal cortex of the brain. The FSU receptor is a potential target for TLE therapy.

“What’s striking about this receptor is that it is highly calcium-permeable, which is what we believe underlies the hyperexcitability and the damage to neurons in this region,” Kumar said.

When FSU receptors allow too much calcium to enter neurons, TLE patients experience epileptic seizures as neurons become overstimulated from the influx. The overstimulation, or hyperexcitability, is what causes neurons to die, a process known as excitotoxicity.

The research team also found that the amino acid D-serine blocks these receptors to prevent excess levels of calcium from reaching neurons, thereby preventing seizure activity and neuronal death.

“What’s unique about D-serine, unlike any other drugs that are out there, is that D-serine is made in the brain itself, so it’s well-tolerated by the brain,” Kumar said. “Many medications that deal with treating TLE are not well-tolerated, but given that this is made in the brain, it works very well.”

With assistance from Michael Roper’s lab in the FSU Department of Chemistry and Biochemistry, the research team found that D-serine levels were depleted in epileptic animals, indicating that TLE patients may not produce D-serine like they should.

“The loss of D-serine essentially removes the brakes on these neurons, making them hyperexcitable,” Kumar said. “Then, the calcium comes in and causes excitotoxicity, which is the reason why neurons die. So, if we provide the brakes — if we provide D-serine — then you don’t get that loss of neurons.”

Kumar’s research points to neuroinflammation as the cause for diminished D-serine levels in the entorhinal cortex of the brain. D-serine is typically produced by glial cells, but neuroinflammation experienced as part of TLE causes cellular and molecular changes in the brain that can prevent it from being produced.

The next step in exploring D-serine as a viable therapy is investigating potential administration techniques.

“We have to find creative ways to administer D-serine to that particular region of the human brain,” Kumar said. “Getting it to that right place is the challenge. We have to look at what effect it has when administered locally to that region of the brain compared to systemically through an IV, for example.”

TLE often results from an injury such as a concussion or other traumatic brain injury. When administered to the appropriate region, D-serine has been shown to work in preventing the secondary effects of such an injury.

“A pie-in-the-sky type idea is a hypothetical scenario where you were to have a nebulizer, or have people inhale D-serine, go play football, and if they experience a concussion, no neurons would be lost because the D-serine would provide a sort of cushion just in case there is a traumatic brain injury that can lead to loss of neurons in the temporal lobe,” Kumar said.

“There are some very interesting questions to ask and solve,” he added. “The important thing is that we’ve outlined the basic bread-and-butter mechanisms of why D-serine works. What we’ve established is the discovery of the receptors, discovery of the antagonist for these receptors (D-serine), how it works and how to prevent the emergence of TLE. The mechanisms and pathophysiology are as relevant to the animal model as they are to human beings, and that’s where the excitement lies.”