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Scientists create precursor to life in thermal vent experiment
Scientists speculate that if life were to have spontaneously developed on Earth, the first thing there would need to be are vesicles.
- The findings also suggest that life may have formed in the deep oceans of other celestial bodies in our solar system as well.
- These are a lot like cell membranes, only they don't contain any of the complicated machinery that real, living cells do.
- Researchers recently demonstrated that these vesicles form frequently in environments similar to the hydrothermal vents of early Earth.
One of the hallmarks of life is homeostasis, or the ability for life to maintain a consistent internal state regardless of external conditions. Think of how you sweat to cool down, or how you need to drink water every now and again to maintain fluid levels.
This need to maintain homeostasis is present in all forms of life by definition. But in order for there to be homeostasis, there needs to be an inside and an outside. Now, a new study published in Nature Ecology & Evolution on November 4, may have identified how life first developed the barriers between cells' insides and their outsides.
What are vesicles?
Examples of a lipid bilayer, a liposome (a.k.a., a vesicle, or a protocell), and a micelle, which is a type of structure composed of only one layer of lipids.
Image source: Wikimedia Commons
Biologists believe that before life could develop on Earth, the first thing that needed to occur was the development of protocells. You can think of this like a cell minus all of the machinery that makes a cell work. Instead, a protocell is just composed of a membrane that defines inside and outside.
Nearly every organism's cell membrane is composed of a lipid bilayer, meaning that it's likely that life started out with these bilayers. A lipid is what's known as an amphiphilic molecules, which are molecules that have one side attracted to water and one side repelled by it. When there are two "sheets" of these molecules, they can form a barrier where the water-loving heads of the molecules face outward while the water-hating tails face inward. Sometimes, these sheets also form a sphere, or vesicle. These vesicles are essentially cell membranes.
Many scientists believe that the formation of vesicles was the first step toward life. Vesicles keep certain material out of the protocell while protecting an internal solution — homeostasis. But the question of where and how they formed is less clear.
Could vesicles have formed around hydrothermal vents?
An artists depiction of the water vapor plumes found on Enceladus, which are believed to caused by subsurface hydrothermal vents.
Image source: NASA / JPL-Caltech
The earliest direct evidence of life dates back to 3.5 billion years ago in the form of fossilized microorganisms, but life clearly existed before then. A 2017 study claims to have identified fossilized microorganisms dating back to 4.28 billion years ago, a mere 400 million years after the formation of the Earth itself. But this finding is contested, not just because it implies life sprang into action as soon as it could but because of where it was found: in the precipitate of hydrothermal vents.
The interesting chemistry and energy source that characterized hydrothermal vents has long made them a candidate for the origin of life, but experiments have failed to demonstrate that vesicles can form there. The environment around hydrothermal vents in the Hadean/early Archaean period when life began was highly alkaline, or basic, and extremely salty, even saltier than today's oceans are. When scientists attempted to create vesicles under such conditions, they simply fell apart, leading some scientists to argue that life probably began in freshwater pools, away from the highly alkaline and salty environment of hydrothermal vents.
However, this new study indicates that not only can protocells develop in this environment, it actually encourages their development. One of the study's authors, Dr. Sean Jordan, explains why their results were different: "Other experiments had all used a small number of molecule types, mostly with fatty acids of the same size, whereas in natural environments, you would expect to see a wider array of molecules."
Then and now.
Prior experiments were extremely precise, failing to replicate that messier nature of the hydrothermal vent environment — Jordan's experiment, however, featured numerous amphiphilic molecules. In fact, molecules with longer carbon chains required the heat of a hydrothermal vent to form vesicles, the alkalinity helped the vesicles keep their electrical charge, and the salt in the solution ensured helped the molecules pack together more tightly.
Not only does this suggest that life on Earth may have started in the deep oceans by hydrothermal vents, it also points to places in our solar system where life may develop or have developed as well. Celestial objects such as Europa, one of Jupiter's moons, may harbor life despite the miles-deep shell of ice that encases it. The moon's orbit constantly squeezes and unsqueezes it, providing heat for a liquid subsurface ocean that observations suggest may be salty and alkaline as well. Saturn's moon Enceladus is covered in geysers shooting water vapor, thought to be caused by hydrothermal vents, that contain salts and organic compounds.
Together, these facts paint a picture about the formation of life; not only might life first develop deep in the ocean near hydrothermal vents, but it might develop as soon as its able, and often. If this finding is backed up by further evidence, and if we find that life began nearly as soon as the oceans formed on Earth, we may have a very good shot at finding life in our solar system on the moons of Jupiter and Saturn.
Certain water beetles can escape from frogs after being consumed.
- A Japanese scientist shows that some beetles can wiggle out of frog's butts after being eaten whole.
- The research suggests the beetle can get out in as little as 7 minutes.
- Most of the beetles swallowed in the experiment survived with no complications after being excreted.
In what is perhaps one of the weirdest experiments ever that comes from the category of "why did anyone need to know this?" scientists have proven that the Regimbartia attenuata beetle can climb out of a frog's butt after being eaten.
The research was carried out by Kobe University ecologist Shinji Sugiura. His team found that the majority of beetles swallowed by black-spotted pond frogs (Pelophylax nigromaculatus) used in their experiment managed to escape about 6 hours after and were perfectly fine.
"Here, I report active escape of the aquatic beetle R. attenuata from the vents of five frog species via the digestive tract," writes Sugiura in a new paper, adding "although adult beetles were easily eaten by frogs, 90 percent of swallowed beetles were excreted within six hours after being eaten and, surprisingly, were still alive."
One bug even got out in as little as 7 minutes.
Sugiura also tried putting wax on the legs of some of the beetles, preventing them from moving. These ones were not able to make it out alive, taking from 38 to 150 hours to be digested.
Naturally, as anyone would upon encountering such a story, you're wondering where's the video. Thankfully, the scientists recorded the proceedings:
The Regimbartia attenuata beetle can be found in the tropics, especially as pests in fish hatcheries. It's not the only kind of creature that can survive being swallowed. A recent study showed that snake eels are able to burrow out of the stomachs of fish using their sharp tails, only to become stuck, die, and be mummified in the gut cavity. Scientists are calling the beetle's ability the first documented "active prey escape." Usually, such travelers through the digestive tract have particular adaptations that make it possible for them to withstand extreme pH and lack of oxygen. The researchers think the beetle's trick is in inducing the frog to open a so-called "vent" controlled by the sphincter muscle.
"Individuals were always excreted head first from the frog vent, suggesting that R. attenuata stimulates the hind gut, urging the frog to defecate," explains Sugiura.
For more information, check out the study published in Current Biology.
Are "humanized" pigs the future of medical research?
The U.S. Food and Drug Administration requires all new medicines to be tested in animals before use in people. Pigs make better medical research subjects than mice, because they are closer to humans in size, physiology and genetic makeup.
In recent years, our team at Iowa State University has found a way to make pigs an even closer stand-in for humans. We have successfully transferred components of the human immune system into pigs that lack a functional immune system. This breakthrough has the potential to accelerate medical research in many areas, including virus and vaccine research, as well as cancer and stem cell therapeutics.
Existing biomedical models
Severe Combined Immunodeficiency, or SCID, is a genetic condition that causes impaired development of the immune system. People can develop SCID, as dramatized in the 1976 movie “The Boy in the Plastic Bubble." Other animals can develop SCID, too, including mice.
Researchers in the 1980s recognized that SCID mice could be implanted with human immune cells for further study. Such mice are called “humanized" mice and have been optimized over the past 30 years to study many questions relevant to human health.
Mice are the most commonly used animal in biomedical research, but results from mice often do not translate well to human responses, thanks to differences in metabolism, size and divergent cell functions compared with people.
Nonhuman primates are also used for medical research and are certainly closer stand-ins for humans. But using them for this purpose raises numerous ethical considerations. With these concerns in mind, the National Institutes of Health retired most of its chimpanzees from biomedical research in 2013.
Alternative animal models are in demand.
Swine are a viable option for medical research because of their similarities to humans. And with their widespread commercial use, pigs are met with fewer ethical dilemmas than primates. Upwards of 100 million hogs are slaughtered each year for food in the U.S.
In 2012, groups at Iowa State University and Kansas State University, including Jack Dekkers, an expert in animal breeding and genetics, and Raymond Rowland, a specialist in animal diseases, serendipitously discovered a naturally occurring genetic mutation in pigs that caused SCID. We wondered if we could develop these pigs to create a new biomedical model.
Our group has worked for nearly a decade developing and optimizing SCID pigs for applications in biomedical research. In 2018, we achieved a twofold milestone when working with animal physiologist Jason Ross and his lab. Together we developed a more immunocompromised pig than the original SCID pig – and successfully humanized it, by transferring cultured human immune stem cells into the livers of developing piglets.
During early fetal development, immune cells develop within the liver, providing an opportunity to introduce human cells. We inject human immune stem cells into fetal pig livers using ultrasound imaging as a guide. As the pig fetus develops, the injected human immune stem cells begin to differentiate – or change into other kinds of cells – and spread through the pig's body. Once SCID piglets are born, we can detect human immune cells in their blood, liver, spleen and thymus gland. This humanization is what makes them so valuable for testing new medical treatments.
We have found that human ovarian tumors survive and grow in SCID pigs, giving us an opportunity to study ovarian cancer in a new way. Similarly, because human skin survives on SCID pigs, scientists may be able to develop new treatments for skin burns. Other research possibilities are numerous.
The ultraclean SCID pig biocontainment facility in Ames, Iowa. Adeline Boettcher, CC BY-SA
Pigs in a bubble
Since our pigs lack essential components of their immune system, they are extremely susceptible to infection and require special housing to help reduce exposure to pathogens.
SCID pigs are raised in bubble biocontainment facilities. Positive pressure rooms, which maintain a higher air pressure than the surrounding environment to keep pathogens out, are coupled with highly filtered air and water. All personnel are required to wear full personal protective equipment. We typically have anywhere from two to 15 SCID pigs and breeding animals at a given time. (Our breeding animals do not have SCID, but they are genetic carriers of the mutation, so their offspring may have SCID.)
As with any animal research, ethical considerations are always front and center. All our protocols are approved by Iowa State University's Institutional Animal Care and Use Committee and are in accordance with The National Institutes of Health's Guide for the Care and Use of Laboratory Animals.
Every day, twice a day, our pigs are checked by expert caretakers who monitor their health status and provide engagement. We have veterinarians on call. If any pigs fall ill, and drug or antibiotic intervention does not improve their condition, the animals are humanely euthanized.
Our goal is to continue optimizing our humanized SCID pigs so they can be more readily available for stem cell therapy testing, as well as research in other areas, including cancer. We hope the development of the SCID pig model will pave the way for advancements in therapeutic testing, with the long-term goal of improving human patient outcomes.
Adeline Boettcher earned her research-based Ph.D. working on the SCID project in 2019.
Satellite imagery can help better predict volcanic eruptions by monitoring changes in surface temperature near volcanoes.
- A recent study used data collected by NASA satellites to conduct a statistical analysis of surface temperatures near volcanoes that erupted from 2002 to 2019.
- The results showed that surface temperatures near volcanoes gradually increased in the months and years prior to eruptions.
- The method was able to detect potential eruptions that were not anticipated by other volcano monitoring methods, such as eruptions in Japan in 2014 and Chile in 2015.
How can modern technology help warn us of impending volcanic eruptions?
One promising answer may lie in satellite imagery. In a recent study published in Nature Geoscience, researchers used infrared data collected by NASA satellites to study the conditions near volcanoes in the months and years before they erupted.
The results revealed a pattern: Prior to eruptions, an unusually large amount of heat had been escaping through soil near volcanoes. This diffusion of subterranean heat — which is a byproduct of "large-scale thermal unrest" — could potentially represent a warning sign of future eruptions.
Conceptual model of large-scale thermal unrestCredit: Girona et al.
For the study, the researchers conducted a statistical analysis of changes in surface temperature near volcanoes, using data collected over 16.5 years by NASA's Terra and Aqua satellites. The results showed that eruptions tended to occur around the time when surface temperatures near the volcanoes peaked.
Eruptions were preceded by "subtle but significant long-term (years), large-scale (tens of square kilometres) increases in their radiant heat flux (up to ~1 °C in median radiant temperature)," the researchers wrote. After eruptions, surface temperatures reliably decreased, though the cool-down period took longer for bigger eruptions.
"Volcanoes can experience thermal unrest for several years before eruption," the researchers wrote. "This thermal unrest is dominated by a large-scale phenomenon operating over extensive areas of volcanic edifices, can be an early indicator of volcanic reactivation, can increase prior to different types of eruption and can be tracked through a statistical analysis of little-processed (that is, radiance or radiant temperature) satellite-based remote sensing data with high temporal resolution."
Temporal variations of target volcanoesCredit: Girona et al.
Although using satellites to monitor thermal unrest wouldn't enable scientists to make hyper-specific eruption predictions (like predicting the exact day), it could significantly improve prediction efforts. Seismologists and volcanologists currently use a range of techniques to forecast eruptions, including monitoring for gas emissions, ground deformation, and changes to nearby water channels, to name a few.
Still, none of these techniques have proven completely reliable, both because of the science and the practical barriers (e.g. funding) standing in the way of large-scale monitoring. In 2014, for example, Japan's Mount Ontake suddenly erupted, killing 63 people. It was the nation's deadliest eruption in nearly a century.
In the study, the researchers found that surface temperatures near Mount Ontake had been increasing in the two years prior to the eruption. To date, no other monitoring method has detected "well-defined" warning signs for the 2014 disaster, the researchers noted.
The researchers hope satellite-based infrared monitoring techniques, combined with existing methods, can improve prediction efforts for volcanic eruptions. Volcanic eruptions have killed about 2,000 people since 2000.
"Our findings can open new horizons to better constrain magma–hydrothermal interaction processes, especially when integrated with other datasets, allowing us to explore the thermal budget of volcanoes and anticipate eruptions that are very difficult to forecast through other geophysical/geochemical methods."