Did Dinosaur-Killing Asteroid Trigger Largest Lava Flows on Earth?

Did Dinosaur-Killing Asteroid Trigger Largest Lava Flows on Earth?

The asteroid that slammed into the ocean off Mexico 66 million years ago and killed off the dinosaurs probably rang the Earth like a bell, triggering volcanic eruptions around the globe that may have contributed to the devastation, according to a team of UC Berkeley geophysicists.

Mark Richards

Specifically, the researchers argue that the impact likely triggered most of the immense eruptions of lava in India known as the Deccan Traps, explaining the “uncomfortably close” coincidence between the Deccan Traps eruptions and the impact, which has always cast doubt on the theory that the asteroid was the sole cause of the end-Cretaceous mass extinction.

“If you try to explain why the largest impact we know of in the last billion years happened within 100,000 years of these massive lava flows at Deccan … the chances of that occurring at random are minuscule,” said team leader Mark Richards, UC Berkeley professor of earth and planetary science. “It’s not a very credible coincidence.”

Richards and his colleagues marshal evidence for their theory that the impact reignited the Deccan flood lavas in a paper to be published in The Geological Society of America Bulletin, available online today (April 30) in advance of publication.

While the Deccan lava flows, which started before the impact but erupted for several hundred thousand years after re-ignition, probably spewed immense amounts of carbon dioxide and other noxious, climate-modifying gases into the atmosphere, it’s still unclear if this contributed to the demise of most of life on Earth at the end of the Age of Dinosaurs, Richards said.

“This connection between the impact and the Deccan lava flows is a great story and might even be true, but it doesn’t yet take us closer to understanding what actually killed the dinosaurs and the ‘forams,’” he said, referring to tiny sea creatures calledforaminifera, many of which disappeared from the fossil record virtually overnight at the boundary between the Cretaceous and Tertiary periods, called the KT boundary. The disappearance of the landscape-dominating dinosaurs is widely credited with ushering in the age of mammals, eventually including humans.

He stresses that his proposal differs from an earlier hypothesis that the energy of the impact was focused around Earth to a spot directly opposite, or antipodal, to the impact, triggering the eruption of the Deccan Traps. The “antipodal focusing” theory died when the impact crater, called Chicxulub, was found off the Yucatán coast of Mexico, which is about 5,000 kilometers from the antipode of the Deccan traps.

Flood basalts

Richards proposed in 1989 that plumes of hot rock, called “plume heads,” rise through Earth’s mantle every 20-30 million years and generate huge lava flows, called flood basalts, like the Deccan Traps. It struck him as more than coincidence that the last four of the six known mass extinctions of life occurred at the same time as one of these massive eruptions.

plume of hot magma underlying India

“Paul Renne’s group at Berkeley showed years ago that the Central Atlantic Magmatic Province is associated with the mass extinction at the Triassic/Jurassic boundary 200 million years ago, and the Siberian Traps are associated with the end Permian extinction 250 million years ago, and now we also know that a big volcanic eruption in China called the Emeishan Traps is associated with the end-Guadalupian extinction 260 million years ago,” Richards said. “Then you have the Deccan eruptions – including the largest mapped lava flows on Earth – occurring 66 million years ago coincident with the KT mass extinction. So what really happened at the KT boundary?”

Richards teamed up with experts in many areas to try to discover faults with his radical idea that the impact triggered the Deccan eruptions, but instead came up with supporting evidence. Paul Renne, a professor in residence in the UC Berkeley Department of Earth and Planetary Science and director of the Berkeley Geochronology Center, re-dated the asteroid impact and mass extinction two years ago and found them essentially simultaneous, but also within approximately 100,000 years of the largest Deccan eruptions, referred to as the Wai subgroup flows, which produced about 70 percent of the lavas that now stretch across the Indian subcontinent from Mumbai to Kolkata.

Michael Manga, a professor in the same department, has shown over the past decade that large earthquakes – equivalent to Japan’s 9.0 Tohoku quake in 2011 – can trigger nearby volcanic eruptions. Richards calculates that the asteroid that created the Chicxulub crater might have generated the equivalent of a magnitude 9 or larger earthquake everywhere on Earth, sufficient to ignite the Deccan flood basalts and perhaps eruptions many places around the globe, including at mid-ocean ridges.

“It’s inconceivable that the impact could have melted a whole lot of rock away from the impact site itself, but if you had a system that already had magma and you gave it a little extra kick, it could produce a big eruption,” Manga said.

Similarly, Deccan lava from before the impact is chemically different from that after the impact, indicating a faster rise to the surface after the impact, while the pattern of dikes from which the supercharged lava flowed – “like cracks in a soufflé,” Renne said – are more randomly oriented post-impact.

“There is a profound break in the style of eruptions and the volume and composition of the eruptions,” said Renne. “The whole question is, ‘Is that discontinuity synchronous with the impact?’”

Western Ghats, India
PHOTOGRAPH OF PART OF THE MAIN STACK OF 66 MILLION YEAR OLD DECCAN TRAPS LAVA FLOWS NEAR THE CITY OF MAHABALESHWAR, INDIA. THE ENTIRE VOLUME OF THE DECCAN TRAPS COULD HAVE COVERED AN AREA AS LARGE AS THE STATE OF CALIFORNIA IN A MILE DEEP PILE OF LAVA FLOWS. (MARK RICHARDS PHOTO)

Reawakened volcanism

Richards, Renne and graduate student Courtney Sprain, along with Deccan volcanology experts Steven Self and Loÿc Vanderkluysen, visited India in April 2014 to obtain lava samples for dating, and noticed that there are pronounced weathering surfaces, or terraces, marking the onset of the huge Wai subgroup flows. Geological evidence suggests that these terraces may signal a period of quiescence in Deccan volcanism prior to the Chicxulub impact. Apparently never before noticed, these terraces are part of the western Ghats, a mountain chain named after the Hindu word for steps.

Since the team’s paper was accepted for publication, a group from Princeton University published new radioisotopic dates for the Deccan Traps lavas that are consistent with these predictions. Renne and Sprain at UC Berkeley also have preliminary, unpublished dates for the Deccan lavas that could help solidify Richards’ theory, Renne said.“This was an existing massive volcanic system that had been there probably several million years, and the impact gave this thing a shake and it mobilized a huge amount of magma over a short amount of time,” Richards said. “The beauty of this theory is that it is very testable, because it predicts that you should have the impact and the beginning of the extinction, and within 100,000 years or so you should have these massive eruptions coming out, which is about how long it might take for the magma to reach the surface.”

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Sixth DNA Base Discovered?

Sixth DNA Base Discovered?

DNA (deoxyribonucleic acid) is the main component of our genetic material. It is formed by combining four parts: A, C, G and T (adenine, cytosine, guanine and thymine), called bases of DNA combine in thousands of possible sequences to provide the genetic variability that enables the wealth of aspects and functions of living beings.

Two more bases: the Methyl- cytosine and Methyl-adenine

In the early 80s, to these four “classic” bases of DNA was added a fifth: the methyl-cytosine (mC) derived from cytosine. And it was in the late 90’s when mC was recognized as the main cause of epigenetic mechanisms: it is able to switch genes on or off depending on the physiological needs of each tissue.

In recent years, interest in this fifth DNA base has increased by showing that alterations in the methyl-cytosine contribute to the development of many human diseases, including cancer.

Today, an article published in Cell by Manel Esteller, director of the Epigenetics and Cancer Biology Program of the Bellvitge Biomedical Research Institute (IDIBELL), ICREA researcher and Professor of Genetics at the University of Barcelona, describes the possible existence of a sixth DNA base, the methyl-adenine (mA), which also help determine the epigenome and would therefore be key in the life of the cells.

In bacteria and in complex organisms

“It was known for years that bacteria, evolutionarily very distant living organisms of us, had mA in its genome with a protective function against the insertion of genetic material from other organisms. But it was believed that this was a phenomenon of primitive cells and it was very static” describes Manel Esteller.

“However, this issue of Cell publishes three papers suggesting that more complex cells called eukaryotes such as the human body cells, also present the sixth DNA base. These studies suggest that algae, worms and flies possess mA and it acts to regulate the expression of certain genes, thus constituting a new epigenetic mark. This work has been possible thanks to the development of analytical methods with high sensitivity because levels of mA in described genomes are low. In addition it seems that mA would play a specific role in stem cells and early stages of development, “explains the researcher.

“Now the challenge we face is to confirm this data and find out whether mammals, including humans, we also have this sixth DNA base, and consider what its role is.”

Beyond Genes: Are Centrioles Carriers of Biological Information?

Beyond Genes: Are Centrioles Carriers of Biological Information?

Centrioles are barrel-shaped structures inside cells, made up of multiple proteins. They are currently the focus of much research, since mutations in the proteins that make them up can cause a broad range of diseases, including developmental abnormalities, respiratory conditions, male sterility and cancer. Publishing in the Nature journal Cell Research, EPFL scientists show that the original centrioles of a fertilized egg, which only come from the father, persist across tens of cell divisions in the developing embryo. The surprising finding raises the possibility that centrioles may actually be carriers of information, with profound implications for biology and disease treatment.

Perhaps best known for their role in cell division, centrioles ensure that chromosomes are properly passed on to the new daughter cells. However, they are also found in cilia, the long eyelash-like structures that allow many cells in the body to signal to their neighbors and other cells to exhibit motility, e.g. in cells that line the respiratory tracts. During reproduction, both parents equally contribute genetic material, while the female egg donates most of the cell organelles, such as mitochondria. However, the centrioles of the newly fertilized embryo come exclusively from the male’s sperm, bringing with them any malfunctions to the first embryo cells.

Passing information across generations

The lab of Pierre Gönczy at EPFL’s Swiss Institute for Experimental Cancer Research has found that centrioles can carry such information beyond the first cells to many of a developing embryo to several cell generations. The study focused on the worm C. elegans, which is commonly used as a model organism for embryonic development and human genetic diseases. As in other species, including humans, centrioles inC. elegans are only contributed by sperm cells. Gönczy’s team wanted to know how far do these “original” centrioles last across the cell divisions that turn a fertilized egg into a fully formed embryo.

In order to track the fate of the centrioles, the scientists used genetically modified versions of C. elegans, in which they could tag three different centriole proteins with a fluorescent signal. Tagged male worms were mated to untagged females, so that the scientists could specifically track centriole components that were contributed from the father during the course of embryogenesis.

Gönczy’s team imaged the fluorescent signals at different cell divisions of the developing embryos, and discovered that paternally contributed centriole proteins can actually persist up to ten cell generations. The data show for the first time that centrioles are remarkably persistent in the developing embryo.

Even more intriguing are the implications the study has for biology at large, as it raises the possibility that centrioles, persisting across several cell cycles, could effectively be a non-genetic information carrier. If this were confirmed, it could represent a paradigm shift in the way we think and understand the biology of an organelle that has been present across eukaryotic evolution.

Nonetheless, this does not detract from the value this study holds for medicine. Considering the number of diseases associated with centrioles, this could open the way for innovative treatment approaches. In particular, the study demonstrates how malfunctioning centrioles can pass directly from the father and well into the life of the embryo. This can have serious implications for the way we understand centriole diseases.

“Centrioles have always been seen as something that just jumpstarts the development of the embryo,” says Pierre Gönczy. “Here we show that centrioles could be the means of a unidirectional inheritance of information, with considerable impact in early development.” His team will next investigate if the exceptional persistence of centrioles extends to other systems, including human cells.

Reference

Balestra FR, von Tobel L, Gönczy P. Paternally contributed centrioles exhibit exceptional persistence in C. elegans embryos. Cell Research 24 April 2015. DOI: 10.1038/cr.2015.49

Bacterial Flora of Remote Tribespeople Carries Antibiotic Resistance Genes

Bacterial Flora of Remote Tribespeople Carries Antibiotic Resistance Genes

Scientists have found antibiotic resistance genes in the bacterial flora of a South American tribe that never before had been exposed to antibiotic drugs. The findings suggest that bacteria in the human body have had the ability to resist antibiotics since long before such drugs were ever used to treat disease.

Huts in an isolated village inhabited by Yanomami Amerindians in a remote, mountainous area in southern Venezuela. Members of the tribe were isolated from the modern world and had never been exposed to antibiotic drugs, but the bacteria on their skin and in their mouths and intestines still had antibiotic resistance genes. (Photo: Oscar Noya-Alarcon)

The research stems from the 2009 discovery of a tribe of Yanomami Amerindians in a remote mountainous area in southern Venezuela. Largely because the tribe had been isolated from other societies for more than 11,000 years, its members were found to have among the most diverse collections of bacteria recorded in humans. Within that plethora of bacteria, though, the researchers have identified genes wired to resist antibiotics.

The study, published April 17 in Science Advances, reports that the microbial populations on the skin and in the mouths and intestines of the Yanomami tribespeople were much more diverse than those found in people from the United States and Europe. The multicenter research was conducted by scientists at New York University School of Medicine, Washington University School of Medicine in St. Louis, the Venezuelan Institute of Scientific Research and other institutions.

“This was an ideal opportunity to study how the connections between microbes and humans evolve when free of modern society’s influences,” said Gautam Dantas, PhD, associate professor of pathology and immunology at Washington University and one of the study’s authors. “Such influences include international travel and exposure to antibiotics.”

Dantas

Intriguingly, in Dantas’ lab, graduate student Erica Pehrsson searched for and found antibiotic resistance genes in bacteria on the skin and in the mouths and intestines of tribe members long isolated from such outside influences.

“These people had no exposure to modern antibiotics; their only potential intake of antibiotics could be through the accidental ingestion of soil bacteria that make naturally occurring versions of these drugs,” Pehrsson said. “Yet we were able to identify several genes in bacteria from their fecal and oral samples that deactivate natural, semi-synthetic and synthetic drugs.”

Thousands of years before people began using antibiotics to fight infections, soil bacteria began producing natural antibiotics to kill competitors. Similarly, microbes evolved defenses to protect themselves from the antibiotics their bacterial competitors would make, likely by acquiring resistance genes from the producers themselves through a process known as horizontal gene transfer.

In recent years, the abundance of antibiotics in medicine and agriculture has accelerated this process, stimulating the development and spread of genes that help bacteria survive exposure to antibiotics. Consequently, strains of human disease that are much harder to treat have emerged.

“We have already run out of drugs to treat some types of multidrug-resistant infections, many of which can be lethal, raising the bleak prospect of a post-antibiotic era,” Dantas said.

Scientists don’t really know whether the diversity of specific bacteria improves or harms health, Dantas said, but added that the microbiomes of people in industrialized countries are about 40 percent less diverse than what was found in the tribespeople never exposed to antibiotics.

“Our results bolster a growing body of data suggesting a link between, on one hand, decreased bacterial diversity, industrialized diets and modern antibiotics, and on the other, immunological and metabolic diseases — such as obesity, asthma, allergies and diabetes, which have dramatically increased since the 1970s,” said Maria Dominguez-Bello, PhD, associate professor of medicine at New York University Langone Medical Center and senior author of the study. “We believe there is something occurring in the environment during the past 30 years that has been driving these diseases, and we think the microbiome could be involved.”

The study’s senior author, M. Gloria Dominguez-Bello, PhD, of New York University Langone Medical Center (right), and co-author Oscar Noya-Alarcon, PhD, of the University of Central Venezuela, on the Amazon River in southern Venezuela. (Credit: M. Gloria Dominguez-Bello)

Dominguez-Bello said the research suggests a link between modern antibiotics, diets in industrialized parts of the world and a greatly reduced diversity in the human microbiome — the trillions of bacteria that live in and on the body and that are increasingly being recognized as vital to good health.

The vast majority of human microbiome studies have focused on Western populations, so access to people unexposed to antibiotics and processed diets may shed light on how the human microbiome has changed in response to modern culture, and may point to therapies that can address disease-causing imbalances in the microbiome.

In the current study, when the researchers exposed cultured bacterial species from the tribe to 23 different antibiotics, the drugs were able to kill all of the bacteria. However, the scientists suspected that these susceptible bacteria might carry silent antibiotic resistance genes that could be activated upon exposure to antibiotics.

They tested for such activation, and the tests confirmed their suspicions. The bacterial samples contained many antibiotic resistance genes that can fend off many modern antibiotics. These genes may turn on in response to antibiotic exposure.

“However, we know that easily cultured bacteria represent less than 1 percent of the human microbiota, and we wanted to know more about potential resistance in the uncultured majority of microbes,” Dantas said.

So the researchers applied the same method, called functional metagenomics, to identify functional antibiotic resistance genes from Yanomami fecal and oral samples without any prior culturing. From that experiment they were able to identify nearly 30 additional resistance genes. Many of these genes deactivated natural antibiotics, but the scientists also found multiple genes that could resist semi-synthetic and synthetic antibiotics.

“These include, for example, third- and fourth-generation cephalosporins, which are drugs we try to reserve to fight some of the worst infections,” said Dantas. “It was alarming to find genes from the tribespeople that would deactivate these modern, synthetic drugs.”

As for how bacteria could resist drugs that such microbes never before had encountered, the researchers point to the possibility of cross-resistance, when genes that resist natural antibiotics also have the ability to resist related synthetic antibiotics.

“We’ve seen resistance emerge in the clinic to every new class of antibiotics, and this appears to be because resistance mechanisms are a natural feature of most bacteria and are just waiting to be activated or acquired with exposure to antibiotics,” Dantas said.

Black Holes Don’t Erase Information, Scientists Say

Black Holes Don’t Erase Information, Scientists Say

Shred a document, and you can piece it back together. Burn a book, and you could theoretically do the same. But send information into a black hole, and it’s lost forever.

That’s what some physicists have argued for years: That black holes are the ultimate vaults, entities that suck in information and then evaporate without leaving behind any clues as to what they once contained.

But new research shows that this perspective may not be correct.

“According to our work, information isn’t lost once it enters a black hole,” says Dejan Stojkovic, PhD, associate professor of physics at the University at Buffalo. “It doesn’t just disappear.”

Stojkovic’s new study, “Radiation from a Collapsing Object is Manifestly Unitary,” appeared on March 17 in Physical Review Letters, with UB PhD student Anshul Saini as co-author.

The paper outlines how interactions between particles emitted by a black hole can reveal information about what lies within, such as characteristics of the object that formed the black hole to begin with, and characteristics of the matter and energy drawn inside.

This is an important discovery, Stojkovic says, because even physicists who believed information was not lost in black holes have struggled to show, mathematically, how this happens. His new paper presents explicit calculations demonstrating how information is preserved, he says.

The research marks a significant step toward solving the “information loss paradox,” a problem that has plagued physics for almost 40 years, since Stephen Hawking first proposed that black holes could radiate energy and evaporate over time. This posed a huge problem for the field of physics because it meant that information inside a black hole could be permanently lost when the black hole disappeared — a violation of quantum mechanics, which states that information must be conserved.

Information hidden in particle interactions

In the 1970s, Hawking proposed that black holes were capable of radiating particles, and that the energy lost through this process would cause the black holes to shrink and eventually disappear. Hawking further concluded that the particles emitted by a black hole would provide no clues about what lay inside, meaning that any information held within a black hole would be completely lost once the entity evaporated.

Though Hawking later said he was wrong and that information could escape from black holes, the subject of whether and how it’s possible to recover information from a black hole has remained a topic of debate.

Stojkovic and Saini’s new paper helps to clarify the story.

Instead of looking only at the particles a black hole emits, the study also takes into account the subtle interactions between the particles. By doing so, the research finds that it is possible for an observer standing outside of a black hole to recover information about what lies within.

Interactions between particles can range from gravitational attraction to the exchange of mediators like photons between particles. Such “correlations” have long been known to exist, but many scientists discounted them as unimportant in the past.

“These correlations were often ignored in related calculations since they were thought to be small and not capable of making a significant difference,” Stojkovic says. “Our explicit calculations show that though the correlations start off very small, they grow in time and become large enough to change the outcome.”

The study was partially funded by the National Science Foundation.