Ancient Earth might have had an extraterrestrial supply of vitamin B3 delivered by carbon-rich meteorites, according to a new analysis by NASA-funded researchers. The result supports a theory that the origin of life may have been assisted by a supply of key molecules created in space and brought to Earth by comet and meteor impacts.
"It is always difficult to put a value on the connection between meteorites and the origin of life; for example, earlier work has shown that vitamin B3 could have been produced non-biologically on ancient Earth, but it’s possible that an added source of vitamin B3 could have been helpful," said Karen Smith of Pennsylvania State University in University Park, Pa. "Vitamin B3, also called nicotinic acid or niacin, is a precursor to NAD (nicotinamide adenine dinucleotide), which is essential to metabolism and likely very ancient in origin."
In the new work at Goddard’s Astrobiology Analytical Laboratory, Smith and her team analyzed samples from eight different carbon-rich meteorites, called “CM-2 type carbonaceous chondrites” and found vitamin B3 at levels ranging from about 30 to 600 parts-per-billion. They also found other pyridine carboxylic acids at similar concentrations and, for the first time, found pyridine dicarboxylic acids.
"We discovered a pattern – less vitamin B3 (and other pyridine carboxylic acids) was found in meteorites that came from asteroids that were more altered by liquid water. One possibility may be that these molecules were destroyed during the prolonged contact with liquid water," said Smith. "We also performed preliminary laboratory experiments simulating conditions in interstellar space and showed that the synthesis of vitamin B3 and other pyridine carboxylic acids might be possible on ice grains."
Scientists think the solar system formed when a dense cloud of gas, dust, and ice grains collapsed under its own gravity. Clumps of dust and ice aggregated into comets and asteroids, some of which collided together to form moon-sized objects or planetesimals, and some of those eventually merged to become planets.
Space is filled with radiation from nearby stars as well as from violent events in deep space like exploding stars and black holes devouring matter. This radiation could have powered chemical reactions in the cloud (nebula) that formed the solar system, and some of those reactions may have produced biologically important molecules like vitamin B3.
The team doubts the vitamin B3 and other molecules found in their meteorites came from terrestrial life for two reasons. First, the vitamin B3 was found along with its structural isomers – related molecules that have the same chemical formula but whose atoms are attached in a different order. These other molecules aren’t used by life. Non-biological chemistry tends to produce a wide variety of molecules—basically everything permitted by the materials and conditions present—but life makes only the molecules it needs. If contamination from terrestrial life was the source of the vitamin B3 in the meteorites, then only the vitamin should have been found, not the other, related molecules.
Second, the amount of vitamin B3 found was related to how much the parent asteroids had been altered by water. This correlation with conditions on the asteroids would be unlikely if the vitamin came from contamination on Earth.
Trillions of microbes live in and on our body. We don’t yet fully understand how these microbial ecosystems develop or the full extent to which they influence our health. Some provide essential nutrients, while others cause disease. A new study now provides some unexpected influences on the contents of these communities, as scientists have found that life history, including level of education, can affect the sorts of microbes that flourish. They think this could help in the diagnosis and treatment of disease. A healthy human provides a home for about 100 trillion bacteria and other microbes. These microbes are known as the microbiome, and normally they live on the body in communities, with specialised populations on different organs.
Only three life history events out of about 160 tested could be associated with a specific microbial community. These were: gender, level of education, and whether or not the subject was breastfed as a child.
This complicated issue may help diagnosis and treatment of illnesses. “If a certain community of bacteria is associated with a specific life history trait,” Schloss said, “it is not such a stretch to imagine that there may be microbiome communities associated with illnesses such as cancer.”
To be sure, these associations are only correlations. Neither Schloss nor hundreds of other scientists working on microbiome data can be sure why certain communities end up on certain body parts of only certain individuals. “We really don’t have a good idea for what determines the type of community you’ll have at any given body site,” Schloss said.
Scientists have moved a step closer to the goal of creating stem cells perfectly matched to a patient’s DNA in order to treat diseases, they announced on Thursday, creating patient-specific cell lines out of the skin cells of two adult men. The advance, described online in the journal Cell Stem Cell, is the first time researchers have achieved “therapeutic cloning” of adults. Therapeutic cloning means producing embryonic cells genetically identical to a donor, usually for the purpose of treating disease. But it is also the first step in reproductive cloning — a technique that has set off controversy.
There is a secret bond between slowness and memory, between speed and forgetting. Consider this utterly commonplace situation: a man is walking down the street. At a certain moment, he tries to recall something, but the recollection escapes him. Automatically he slows down. Meanwhile, a person who wants to forget a disagreeable
incident he has just lived through starts unconsciously to speed up his pace, as if he were trying to distance himself from a thing still too close to him in time.
In existential mathematics, that experience takes the form of two basic equations: the degree of slowness is directly proportion to the intensity of memory; the degree of speed is directly proportional to the intensity of forgetting.
Two Simon Fraser University psychologists have made a brain-related discovery that could revolutionize doctors’ perception and treatment of attention-deficit disorders. This discovery opens up the possibility that environmental and/or genetic factors may hinder or suppress a specific brain activity that the researchers have identified as helping us prevent distraction.
This is the first study to reveal our brains rely on an active suppression mechanism to avoid being distracted by salient irrelevant information when we want to focus on a particular item or task.
"Distraction is a leading cause of injury and death in driving and other high-stakes environments," notes McDonald, the study’s senior author. "There are individual differences in the ability to deal with distraction. New electronic products are designed to grab attention. Suppressing such signals takes effort, and sometimes people can’t seem to do it.
"Moreover, disorders associated with attention deficits, such as ADHD and schizophrenia, may turn out to be due to difficulties in suppressing irrelevant objects rather than difficulty selecting relevant ones."
The researchers are now turning their attention to understanding how we deal with distraction. They’re looking at when and why we can’t suppress potentially distracting objects, whether some of us are better at doing so and why that is the case.
"There’s evidence that attentional abilities decline with age and that women are better than men at certain visual attentional tasks," says Gaspar, the study’s first author.