What the rover found once on the ground was startling: Rather than the expected sedimentary rocks — washed in by rivers and accumulated on the lake bottom — many of the rocks are volcanic in nature. Specifically, they are composed of large grains of olivine, the muddier less-gemlike version of peridot that tints so many of Hawaii’s beaches dark green.

Planetary scientists Roger Wiens, professor of earth, atmospheric, and planetary sciences, and Briony Horgan, associate professor of earth, atmospheric, and planetary sciences, in Purdue’s College of Science, were instrumental in the discovery and analysis of this data, recently published in a suite of papers in the journals Science and Science Advances.

Wiens led the design and construction of Perseverance’s SuperCam, which helps analyze the rock samples and determine their type and origin. Horgan helped select Jezero Crater as the rover’s landing site and now uses the Mastcam-Z cameras on Perseverance to put its discoveries into geological context.

“We started to realize that these layered igneous rocks we were seeing look different from the igneous rocks we have these days on Earth,” Wiens said. “They’re very like igneous rocks on Earth early in its existence.”

The rocks and lava the rover is examining on Mars are nearly 4 billion years old. Rocks that old exist on Earth but are incredibly weathered and beaten, thanks to Earth’s active tectonic plates as well as the weathering effects of billions of years of wind, water and life. On Mars, these rocks are pristine and much easier to analyze and study.

Understanding the rocks on Mars, their evolution and history, and what they reveal about the history of planetary conditions on Mars helps researchers understand how life may have arisen on Mars and how that compares with early life and conditions on ancient Earth.

“One of the reasons we don’t have a great understanding of where and when life first evolved on Earth is because those rocks are mostly gone, so it’s really hard to reconstruct what ancient environments on Earth were like,” Horgan said. “The rocks Perseverance is roving over in Jezero have more or less just been sitting at the surface for billions of years, waiting for us to come look at them. That’s one of the reasons that Mars is an important laboratory for understanding the early solar system.”

Scientists can use conditions on early Mars to help extrapolate the environment and conditions on Earth at the same time when life was beginning to arise. Understanding how, and under what conditions, life began will help scientists know where to look for it on other planets and moons, as well as lead to a deeper understanding of biological processes here on Earth.

The search for life is one of Perseverance’s main goals and one of the reasons it landed in Jezero Crater in the first place. Discovering the potential for habitable environments in something as uninhabitable as Jezero Crater’s aged lava flows raises hopes for what lies in the sedimentary rocks the mission is examining now.

“We’re excited to see even better results about organics and ancient habitable environments,” Horgan said. “I think it’s really setting the stage that Mars is this watery, habitable place, and all the samples we’re getting back are going to help us understand the history of ancient microbial life on Mars.”

The equipment and innovative instruments are helping the rover carry out its mission in a way no other rover yet has, emphasizing the need to land on the planet so scientists can examine and understand what’s really going on.

“From orbit, we looked at these rocks and said, ‘Oh, they have beautiful layers!’ So we thought they were sedimentary rocks,” Horgan said. “And it wasn’t until we were very close up and looked at them, at the millimeter scale, that we understood that these are not sedimentary rocks. They’re actually ancient lava. It was a huge moment when we figured that out on the ground, and it really illustrated why we need this kind of exploration. The tools we have on the rover are vital because it was impossible to understand the origin of these rocks until we got up close and used all our amazing microscopic instruments to look at them.”

The search for life is one of Perseverance’s main goals and one of the reasons it landed in Jezero Crater in the first place. Discovering the potential for habitable environments in something as uninhabitable as Jezero Crater’s aged lava flows raises hopes for what lies in the sedimentary rocks the mission is examining now.

“We’re excited to see even better results about organics and ancient habitable environments,” Horgan said. “I think it’s really setting the stage that Mars is this watery, habitable place, and all the samples we’re getting back are going to help us understand the history of ancient microbial life on Mars.”

The equipment and innovative instruments are helping the rover carry out its mission in a way no other rover yet has, emphasizing the need to land on the planet so scientists can examine and understand what’s really going on.

“From orbit, we looked at these rocks and said, ‘Oh, they have beautiful layers!’ So we thought they were sedimentary rocks,” Horgan said. “And it wasn’t until we were very close up and looked at them, at the millimeter scale, that we understood that these are not sedimentary rocks. They’re actually ancient lava. It was a huge moment when we figured that out on the ground, and it really illustrated why we need this kind of exploration. The tools we have on the rover are vital because it was impossible to understand the origin of these rocks until we got up close and used all our amazing microscopic instruments to look at them.”

In fact, in higher-salinity solutions, the pH inside of nanopores can be as much as 100 times more acidic than in the bulk solution.

The research findings were published Aug. 22 in the journal CHEM.

A better understanding of nanopores can have important consequences for a variety of engineering processes. Think, for example, of clean-water generation using membrane processes; decarbonization technologies for energy systems, including carbon capture and sequestration; hydrogen production and storage; and batteries.

Young-Shin Jun, a professor of energy, environmental and chemical engineering, and Srikanth Singamaneni, the Lilyan & E. Lisle Hughes Professor in the Department of Mechanical Engineering & Materials Science, wanted to understand how pH — the measure of how acidic or basic a liquid is — in nanopores differed from that of the bulk liquid solution they are submerged in.

“pH is a ‘master variable’ for water chemistry,” Jun said. “When it is measured in practice, people are really measuring the pH of the bulk solution, not the pH inside the material’s nanopores.

“And if they are different, that is a big deal because the information about the little tiny space will change the entire prediction in the system.”

Story Source:

Materials provided by Washington University in St. Louis. Original written by Brandie Jefferson. Note: Content may be edited for style and length.

To hear Duke University professor Xinnian Dong tell it, plants can shift from peacetime to wartime production too.

Crops and other plants are often under attack from bacteria, viruses, and other pathogens. When a plant senses a microbial invasion, it makes radical changes in the chemical soup of proteins — the workhorse molecules of life — inside its cells.

In recent years, Dong and her team have been piecing together just how they do it. In a new study published in the journal Cell, Dong and first author Jinlong Wang reveal the key components in plant cells that reprogram their protein-making machinery to fight disease.

Each year, around 15% of crop yield is lost to bacterial and fungal diseases, costing the global economy some $220 billion. Plants rely on their immune system to help them fight back, Dong said.

Unlike animals, plants don’t have specialized immune cells that can travel through the bloodstream to the site of infection; every cell in the plant has to be able to stand and fight to defend itself, quickly shifting into battle mode.

When plants come under attack, they shift their priorities from growth to defense, so cells start synthesizing new proteins and suppress production of others. Then “within two to three hours things return to normal,” Dong said.

The tens of thousands of proteins made in cells do many jobs: catalyzing reactions, serving as chemical messengers, recognizing foreign substances, moving materials in and out. To build a specific protein, genetic instructions in the DNA packed inside the cell’s nucleus are transcribed into a messenger molecule called mRNA. This strand of mRNA then heads out into the cytoplasm, where a structure called a ribosome “reads” the message and translates it into a protein.

In a 2017 study, Dong and her team found that when a plant is infected, certain mRNA molecules are translated into proteins faster than others. What these mRNA molecules have in common, the researchers discovered, is a region at the front end of the RNA strand with recurring letters in its genetic code, where the nucleotide bases adenine and guanine repeat themselves over and over again.

In the new study, Dong, Wang and colleagues show how this region works with other structures inside the cell to activate “wartime” protein production.

They showed that when plants detect a pathogen attack, the molecular signposts that signal the usual starting point for ribosomes to land on and read the mRNA are removed, which keeps the cell from making its typical “peacetime” proteins.

Instead, ribosomes bypass the usual starting point for translation, using the region of recurring As and Gs within the RNA molecule for docking and start reading from there instead.

“They basically take a shortcut,” Dong said.

For plants, fighting infection is a balancing act, Dong said. Allocating more resources to defense means less is available for photosynthesis and other activities in the business of life. Producing too many defense proteins can create collateral damage: plants with an over-active immune system suffer stunted growth.

By understanding how plants strike this balance, Dong said, scientists hope to find new ways to engineer disease-resistant crops without compromising yield.

Dong’s team did the bulk of their experiments in a mustard-like plant called Arabidopsis thaliana. But similar mRNA sequences have been found in other organisms, including fruit flies, mice and humans, so they may play a broader role in controlling protein synthesis in plants and animals alike, Dong said.

This work was supported by grants from the National Science Foundation (IOS-645589, IOS-2041378), National Institutes of Health (R35-GM118036-06) and the Howard Hughes Medical Institute.

Story Source:

Materials provided by Duke University. Original written by Robin A. Smith. Note: Content may be edited for style and length.