A team led by Allen Nutman, a geologist at the University of Wollongong in Australia, visited a rock outcrop that had been buried under a perennial snow patch until warmer temperatures melted it away. They sawed out a chunk of 3.7-billion-year-old rock and took it back to Australia to study.
In it they found the purported stromatolites, along with other clues to ancient life. “It’s a combination of different types of evidence that makes the story so compelling,” says team member Martin Van Kranendonk, a geologist at the University of New South Wales in Kensington, Australia.
The structures are tiny bumps, just 1–4 centimetres tall, whose shape and internal layering strongly resemble ancient and modern stromatolites, Van Kranendonk and his colleagues say. The texture of the surrounding rocks suggests that they were laid down at the bottom of a shallow sea, much as stromatolites are today in places such as the Bahamas and western Australia. And the rocks contain carbonate minerals such as dolomite, which are also common in younger stromatolites.
Nearly 50 years ago, archaeologists in the southern German town of Altenerding (pictured above) unearthed the bones of a young man who died sometime around 570 C.E. Now, DNA salvaged from one of the man’s teeth has confirmed the suspicion that he died of the plague—as did a young woman buried with him. The two were victims of the Plague of Justinian, which killed as many as 50 million people throughout Europe and the Mediterranean in more than a dozen waves between the 6th and the 8th centuries C.E. Researchers have now been able to piece together the DNA sequence of the Yersinia pestis bacterium that killed the man.
The Biomolecule Sequencer investigation sent samples of mouse, virus and bacteria DNA to the space station to test a commercially available DNA sequencing device called MinION, developed by Oxford Nanopore Technologies. The MinION works by sending a positive current through pores embedded in membranes inside the device, called nanopores. At the same time, fluid containing a DNA sample passes through the device. Individual DNA molecules partially block the nanopores and change the current in a way that is unique to that particular DNA sequence. By looking at these changes, researchers can identify the specific DNA sequence.
Rubins, who has a background in molecular biology, conducted the test aboard the station while researchers simultaneously sequenced identical samples on the ground. The tests were set up to attempt to make spaceflight conditions, primarily microgravity, the only variables that could account for differences in results.
Thought-Controlled Nanoscale Robots in a Living Host
We report a new type of brain-machine interface enabling a human operator to control nanometer-size robots inside a living animal by brain activity. Recorded EEG patterns are recognized online by an algorithm, which in turn controls the state of an electromagnetic field. The field induces the local heating of billions of mechanically-actuating DNA origami robots tethered to metal nanoparticles, leading to their reversible activation and subsequent exposure of a bioactive payload. As a proof of principle we demonstrate activation of DNA robots to cause a cellular effect inside the insect Blaberus discoidalis, by a cognitively straining task. This technology enables the online switching of a bioactive molecule on and off in response to a subject’s cognitive state, with potential implications to therapeutic control in disorders such as schizophrenia, depression, and attention deficits, which are among the most challenging conditions to diagnose and treat.
“It’s the most bizarre thing,” says Edward Holmes, a virologist at the University of Sydney, who wasn’t involved in the study. It’s like the virus is dismembered, he says.
“If you compare it to the human body, it’s like a person would have their legs, trunk and arms all in different places,” Holmes says. “Then all the pieces come together in some way to work as one single virus. I don’t think anything else in nature moves this way.”
Massive stars, which terminate their evolution in a cataclysmic explosion called a type-II supernova, are the nuclear engines of galactic nucleosynthesis. Among the elemental species known to be produced in these stars, the radioisotope 60Fe stands out: This radioisotope has no natural, terrestrial production mechanisms; thus, a detection of 60Fe atoms within terrestrial reservoirs is proof for the direct deposition of supernova material within our solar system. We report, in this work, the direct detection of live 60Fe atoms in biologically produced nanocrystals of magnetite, which we selectively extracted from two Pacific Ocean sediment cores. We find that the arrival of supernova material on Earth coincides with the lower Pleistocene boundary (2.7 Ma) and that it terminates around 1.7 Ma.
Zika infection may affect adult brain cells, suggesting risk may not be limited to pregnant women
Concerns over the Zika virus have focused on pregnant women due to mounting evidence that it causes brain abnormalities in developing fetuses. However, new research in mice from scientists at The Rockefeller University and La Jolla Institute for Allergy and Immunology suggests that certain adult brain cells may be vulnerable to infection as well. Among these are populations of cells that serve to replace lost or damaged neurons throughout adulthood, and are also thought to be critical to learning and memory.
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Although more research is needed to determine if this damage has long-term biological implications or the potential to affect behavior, the findings suggest the possibility that the Zika virus, which has become widespread in Central and South America over the past eight months, may be more harmful than previously believed. The new findings were published in Cell Stem Cell on August 18.
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We tend to think of vertebrates as living about as long as we do, give or take 50 to 100 years. Marine species are likely to be very long-lived, but determining their age is particularly difficult. Nielsen et al. used the pulse of carbon-14 produced by nuclear tests in the 1950s—specifically, its incorporation into the eye during development—to determine the age of Greenland sharks. This species is large yet slow-growing. The oldest of the animals that they sampled had lived for nearly 400 years, and they conclude that the species reaches maturity at about 150 years of age.
The so-called neural dust, which the team implanted in the muscles and peripheral nerves of rats, is unique in that ultrasound is used both to power and read out the measurements. Ultrasound technology is already well-developed for hospital use, and ultrasound vibrations can penetrate nearly anywhere in the body, unlike radio waves, the researchers say.
“I think the long-term prospects for neural dust are not only within nerves and the brain, but much broader,“ said Michel Maharbiz, an associate professor of electrical engineering and computer sciences and one of the study’s two main authors. “Having access to in-body telemetry has never been possible because there has been no way to put something supertiny superdeep. But now I can take a speck of nothing and park it next to a nerve or organ, your GI tract or a muscle, and read out the data.“
The basis of the IBM team’s approach is something called deterministic lateral displacement (DLD) separation technology, which was first developed in 2004. DLD is a microfluidic process that uses the laminar flow of fluid through a field of tiny posts to separate particles based on sized [sic]. In this array of pillars, the separation occurs because the smaller particles are moving in the direction of the fluid, while the larger particles get deflected along the direction of pillar asymmetry. This sorting makes it possible to isolate and detect and analyze the particles downstream.
He has shown that largest and most species-rich group of lichens are not alliances between two organisms, as every scientist since Schwendener has claimed. Instead, they’re alliances between three. All this time, a second type of fungus has been hiding in plain view.
“There’s been over 140 years of microscopy,” says Spribille. “The idea that there’s something so fundamental that people have been missing is stunning.”
Now, in a paper available as a preprint before peer review, Kriegstein’s lab and two others at UCSF describe experiments using human tissue that suggest the AXL receptor is at least part of how Zika manages to infect neural stem cells. They also investigated whether certain drugs could keep the virus from replicating in infected cells, detailing promising early results of a common, pregnancy-safe antibiotic called azithromycin.
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