Living on a prairie

Houston conservationist is helping to find new ways to protect local species and ecosystems

Memorial Park, which is currently undergoing a master plan renovation, and other Houston parks can be a great opportunity for introducing urban conservation inside the city limits. Rendering courtesy of Nelson Byrd Woltz

The Houston toad is a species that was discovered in Harris County in the 1950s. It has a very distinct, loud call that reverberates at quite a high pitch. But the Houston toad's call hasn't been heard in the city of Houston for almost 50 years. The species is locally extinct and critically endangered elsewhere. In fact, it's the most endangered amphibian in North America, says Cassidy Brown Johnson, a Rice University lecturer and president of the Coastal Prairie Partnership.

"When we think about extinction, we think of the dodo bird or the woolly mammoth," Johnson says. "But extinction is happening right underneath our noses."

The Houston Zoo has a breeding facility for Houston toad, but other than that, it's extremely unlikely that the Houston toad will ever reside naturally in its namesake city.

"We have modified the environment so heavily, that it'd be a bit of a dicey thing to do [to reintroduce the species] because there are so few of them, it's better to focus on an environment where it's still OK for them," Johnson says. The largest population of the Houston toad is actually in Bastrop, however due to the Bastrop fires in 2011, the species is only just recently back to a good place even there.

Johnson is giving a free lecture in April at Rice regarding extinction, where she'll bring her Astros-named Houston toads, Springer and Julia Morales, as her teacher aids.

Changing tides in conservation
As cities like Houston continue to be developed, scientists and researchers are challenged with finding new ways to effect conservation. Johnson says within the industry, there's been a shift in thinking when it comes to preserving nature.

"There's a new burgeoning movement in conservation called urban conservation," she says. "For a long time, if you talked to the traditional conservationists, the idea of conservation is to protect big spaces — the national and state park systems are the perfect example."

But large parks are expensive and a huge undertaking. It's still the strongest form of conservation, but introducing conservation efforts in a city — perhaps in some of Houston's parks, like Memorial Park or Hermann Park — helps not only the species of animals involved, but also educates the local population and forms a connection with residents.

"That has a twofold kind of benefit," Johnson says. "It protects the greenspace so species to live with us, and then also it makes the connection to this place we try to protect."

Of course, this type of effort is new, and there's not a lot of data to show how this would affect the ecosystem and its species, from the migratory and genetic diversity standpoints. Despite the lack of data, Johnson says this type of effort needs to happen.

"We're going to continue to manipulate the world, and maybe if we started thinking about this now, that we can get to a point were we understand enough were we can make these some sort of functioning ecosystem," she says.

Part of the shift in thinking about these ecosystems has to do with new ways of tracking species and understanding their environments.

"Technology is helping us ask a lot of these questions," Johnson says. "Ecology is surprisingly complicated. There's so many variables. ... I think technology and our advance with computing is definitely going to help us understand it."

Using preservation to solve flooding
The educational component is also very important to conservation, and Johnson is making strides on campus with her class. Last year, her department and her class introduced a pocket prairie right on the Rice campus.

Before it was the fourth largest city in America, Houston was a prairie. That type of ecosystem — thick with prairie grass — is very absorbing when it comes to rain water.

"It's really surprising to people that the trees and all this lushness is actually all artificial," Johnson says. "We know that this ecosystem evolved with the cyclical flooding events that happened here."

This movement to bring back Houston's ancient ecosystem is a new focus on a few prairie conservationist groups — and even the Harris County Flood Control. This has been going on for a while, but recent flooding events have opened the eyes of people now looking for reliable solutions to flooding problems.

"After Hurricane Harvey, people started realizing that this might be one of the solutions we could actually investigate and see if it can help us," Johnson says. "A green space is going to absorb way more water than a parking lot."

Of course, there are other flood solutions being discussed — some even incorporating tech or even a tube system underground.

"Historically, there has been some budding of heads between the environment and technology, but I really think moving forward, those two fields have to work together. We need to use technology to save the environment," Johnson says. "I think Houston is one of the places where that conversation is starting to happen."

Missing the toads

Courtesy of Cassidy Brown Johnson

The Houston toad has been locally extinct since the 1970s.

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Building Houston

 
 

This UH engineer is hoping to make his mark on cancer detection. Photo via UH.edu

Early stage cancer is hard to detect, mostly because traditional diagnostic imaging cannot detect tumors smaller than a certain size. One Houston innovator is looking to change that.

Wei-Chuan Shih, professor of electrical and computer engineering at the University of Houston's Cullen College of Engineering, recently published his findings in IEEE Sensors journal. According to a news release from UH, the cells around cancer tumors are small — ~30-150nm in diameter — and complex, and the precise detection of these exosome-carried biomarkers with molecular specificity has been elusive, until now.

"This work demonstrates, for the first time, that the strong synergy of arrayed radiative coupling and substrate undercut can enable high-performance biosensing in the visible light spectrum where high-quality, low-cost silicon detectors are readily available for point-of-care application," says Shih in the release. "The result is a remarkable sensitivity improvement, with a refractive index sensitivity increase from 207 nm/RIU to 578 nm/RIU."

Wei-Chuan Shih is a professor of electrical and computer engineering at the University of Houston's Cullen College of Engineering. Photo via UH.edu

What Shih has done is essentially restored the electric field around nanodisks, providing accessibility to an otherwise buried enhanced electric field. Nanodisks are antibody-functionalized artificial nanostructures which help capture exosomes with molecular specificity.

"We report radiatively coupled arrayed gold nanodisks on invisible substrate (AGNIS) as a label-free (no need for fluorescent labels), cost-effective, and high-performance platform for molecularly specific exosome biosensing. The AGNIS substrate has been fabricated by wafer-scale nanosphere lithography without the need for costly lithography," says Shih in the release.

This process speeds up screening of the surface proteins of exosomes for diagnostics and biomarker discovery. Current exosome profiling — which relies primarily on DNA sequencing technology, fluorescent techniques such as flow cytometry, or enzyme-linked immunosorbent assay (ELISA) — is labor-intensive and costly. Shih's goal is to amplify the signal by developing the label-free technique, lowering the cost and making diagnosis easier and equitable.

"By decorating the gold nanodisks surface with different antibodies (e.g., CD9, CD63, and CD81), label-free exosome profiling has shown increased expression of all three surface proteins in cancer-derived exosomes," said Shih. "The sensitivity for detecting exosomes is within 112-600 (exosomes/μL), which would be sufficient in many clinical applications."

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