An experiment shows that one of the basic units of life -- nucleobases -- could have originated within giant gas clouds interspersed between the stars.
Essential building blocks of DNA -- compounds called nucleobases -- have been detected for the first time in a simulated environment mimicking gaseous clouds that are found interspersed between stars. The finding, published in the journal Nature Communications, brings us closer to understanding the origins of life on Earth.
"This result could be key to unravelling fundamental questions for humankind, such as what organic compounds existed during the formation of the solar system and how they contributed to the birth of life on Earth" says Yasuhiro Oba of Hokkaido University's Institute of Low Temperature Science.
Scientists have already detected some of the basic organic molecules necessary for the beginnings of life in comets, asteroids, and in interstellar molecular clouds: giant gaseous clouds dispersed between stars. It is thought that these molecules could have reached Earth through meteorite impacts some four billion years ago, providing key ingredients for the chemical cocktail that gave rise to life. Learning how these molecules formed is vital to understanding the origins of life.
The basic structural unit of DNA and RNA is called a nucleotide and is composed of a nucleobase, a sugar, and a phosphate group. Previous studies mimicking the expected conditions in interstellar molecular clouds have detected the presence of sugar and phosphate, but not of nucleobases.
Now, Yasuhiro Oba and colleagues at Hokkaido University, Kyushu University, and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) have used advanced analytical methods to detect the fundamental nucleobases in a simulated interstellar cloud environment.
The team conducted their experiments in an ultra-high vacuum reaction chamber. A gaseous mixture of water, carbon monoxide, ammonia, and methanol was continuously supplied onto a cosmic-dust analogue at a temperature of -263° Celsius. Two deuterium discharge lamps attached to the chamber supplied vacuum ultraviolet light to induce chemical reactions. The process led to the formation of an icy film on the dust analogue inside the chamber.
The team used a high-resolution mass spectrometer and a high-performance liquid chromatograph to analyse the product that formed on the substrate after warming it to room temperature. Recent advances in these technological tools allowed them to detect the presence of the nucleobases cytosine, uracil, thymine, adenine, xanthine, and hypoxanthine. They also detected amino acids, which are the building blocks of proteins, and several kinds of dipeptide, or a dimer of amino acid, in the same product.
The team suspects that past experiments simulating interstellar molecular cloud environments would have produced nucleobases, but that the analytical tools used were not sensitive enough to detect them in complex mixtures.
"Our findings suggest that the processes we reproduced could lead to the formation of the molecular precursors of life," says Yasuhiro Oba. "The results could improve our understanding of the early stages of chemical evolution in space."
From Science Daily
Sep 29, 2019
Oldest galaxy protocluster forms 'queen's court'
Using the Subaru, Keck, and Gemini Telescopes, an international team of astronomers has discovered a collection of 12 galaxies which existed about 13.0 billion years ago. This is the earliest protocluster ever found. One of the 12 galaxies is a giant object, known as Himiko, which was discovered a decade ago by the Subaru Telescope and named for a mythological queen in ancient Japan. This discovery suggests that large structures such as protoclusters already existed when the Universe was only about 800 million years old, 6 percent of its present age.
In the present Universe, galaxy clusters can contain hundreds of members, but how these clusters form is a big question in astronomy. To understand the formation of clusters, astronomers search for possible progenitors in the ancient Universe. A protocluster is a dense system of dozens of galaxies in the early Universe, growing into a cluster.
Yuichi Harikane, a JSPS fellow at the National Astronomical Observatory of Japan who led the team of astronomers explains, "A protocluster is a rare and special system with an extremely high density, and not easy to find. To overcome this problem, we used the wide field of view of the Subaru Telescope to map a large area of the sky and look for protoclusters."
In the map of the Universe made by the Subaru Telescope, the team discovered a protocluster candidate, z66OD, where galaxies are 15 times more concentrated than normal for that era. The team then conducted follow-up spectroscopic observations using the W.M. Keck Observatory and Gemini North telescope, and confirmed 12 galaxies which existed 13.0 billion years ago, making it the earliest protocluster known to date.
Interestingly, one of the 12 galaxies in z66OD was a giant object with a huge body of gas, known as Himiko, which was found previously by the Subaru Telescope in 2009. "It is reasonable to find a protocluster near a massive object, such as Himiko. However, we're surprised to see that Himiko was located not in the center of the protocluster, but on the edge 500 million light-years away from the center." said Masami Ouchi, a team member at the National Astronomical Observatory of Japan and the University of Tokyo, who discovered Himiko in 2009. Ironically, the mythological queen Himiko is also said to have lived cloistered away from her people. Ouchi continues, "It is still not understood why Himiko is not located in the center. These results will be a key for understanding the relationship between clusters and massive galaxies."
From Science Daily
In the present Universe, galaxy clusters can contain hundreds of members, but how these clusters form is a big question in astronomy. To understand the formation of clusters, astronomers search for possible progenitors in the ancient Universe. A protocluster is a dense system of dozens of galaxies in the early Universe, growing into a cluster.
Yuichi Harikane, a JSPS fellow at the National Astronomical Observatory of Japan who led the team of astronomers explains, "A protocluster is a rare and special system with an extremely high density, and not easy to find. To overcome this problem, we used the wide field of view of the Subaru Telescope to map a large area of the sky and look for protoclusters."
In the map of the Universe made by the Subaru Telescope, the team discovered a protocluster candidate, z66OD, where galaxies are 15 times more concentrated than normal for that era. The team then conducted follow-up spectroscopic observations using the W.M. Keck Observatory and Gemini North telescope, and confirmed 12 galaxies which existed 13.0 billion years ago, making it the earliest protocluster known to date.
Interestingly, one of the 12 galaxies in z66OD was a giant object with a huge body of gas, known as Himiko, which was found previously by the Subaru Telescope in 2009. "It is reasonable to find a protocluster near a massive object, such as Himiko. However, we're surprised to see that Himiko was located not in the center of the protocluster, but on the edge 500 million light-years away from the center." said Masami Ouchi, a team member at the National Astronomical Observatory of Japan and the University of Tokyo, who discovered Himiko in 2009. Ironically, the mythological queen Himiko is also said to have lived cloistered away from her people. Ouchi continues, "It is still not understood why Himiko is not located in the center. These results will be a key for understanding the relationship between clusters and massive galaxies."
From Science Daily
Sep 28, 2019
New blood test capable of detecting multiple types of cancer
A new blood test in development has shown ability to screen for numerous types of cancer with a high degree of accuracy, a trial of the test shows. Dana-Farber Cancer Institute investigators will present the results of the multi-center trial during a session today at the European Society for Medical Oncology (ESMO) 2019 Congress.
The test, developed by GRAIL, Inc., uses next-generation sequencing technology to probe DNA for tiny chemical tags (methylation) that influence whether genes are active or inactive. When applied to nearly 3,600 blood samples -- some from patients with cancer, some from people who had not been diagnosed with cancer at the time of the blood draw -- the test successfully picked up a cancer signal from the cancer patient samples, and correctly identified the tissue from where the cancer began (the tissue of origin). The test's specificity -- its ability to return a positive result only when cancer is actually present -- was high, as was its ability to pinpoint the organ or tissue of origin, researchers found.
The new test looks for DNA, which cancer cells shed into the bloodstream when they die. In contrast to "liquid biopsies," which detect genetic mutations or other cancer-related alterations in DNA, the technology focuses on modifications to DNA known as methyl groups. Methyl groups are chemical units that can be attached to DNA, in a process called methylation, to control which genes are "on" and which are "off." Abnormal patterns of methylation turn out to be, in many cases, more indicative of cancer -- and cancer type -- than mutations are. The new test zeroes in on portions of the genome where abnormal methylation patterns are found in cancer cells.
"Our previous work indicated that methylation-based assays outperform traditional DNA-sequencing approaches to detecting multiple forms of cancer in blood samples," said the study's lead author, Geoffrey Oxnard, MD, of Dana-Farber. "The results of the new study demonstrate that such assays are a feasible way of screening people for cancer."
In the study, investigators analyzed cell-free DNA (DNA that had once been confined to cells but had entered the bloodstream upon the cells' death) in 3,583 blood samples, including 1,530 from patients diagnosed with cancer and 2,053 from people without cancer. The patient samples comprised more than 20 types of cancer, including hormone receptor-negative breast, colorectal, esophageal, gallbladder, gastric, head and neck, lung, lymphoid leukemia, multiple myeloma, ovarian, and pancreatic cancer.
The overall specificity was 99.4%, meaning only 0.6% of the results incorrectly indicated that cancer was present. The sensitivity of the assay for detecting a pre-specified high mortality cancers (the percent of blood samples from these patients that tested positive for cancer) was 76%. Within this group, the sensitivity was 32% for patients with stage I cancer; 76% for those with stage II; 85% for stage III; and 93% for stage IV. Sensitivity across all cancer types was 55%, with similar increases in detection by stage. For the 97% of samples that returned a tissue of origin result, the test correctly identified the organ or tissue of origin in 89% of cases.
Read more at Science Daily
The test, developed by GRAIL, Inc., uses next-generation sequencing technology to probe DNA for tiny chemical tags (methylation) that influence whether genes are active or inactive. When applied to nearly 3,600 blood samples -- some from patients with cancer, some from people who had not been diagnosed with cancer at the time of the blood draw -- the test successfully picked up a cancer signal from the cancer patient samples, and correctly identified the tissue from where the cancer began (the tissue of origin). The test's specificity -- its ability to return a positive result only when cancer is actually present -- was high, as was its ability to pinpoint the organ or tissue of origin, researchers found.
The new test looks for DNA, which cancer cells shed into the bloodstream when they die. In contrast to "liquid biopsies," which detect genetic mutations or other cancer-related alterations in DNA, the technology focuses on modifications to DNA known as methyl groups. Methyl groups are chemical units that can be attached to DNA, in a process called methylation, to control which genes are "on" and which are "off." Abnormal patterns of methylation turn out to be, in many cases, more indicative of cancer -- and cancer type -- than mutations are. The new test zeroes in on portions of the genome where abnormal methylation patterns are found in cancer cells.
"Our previous work indicated that methylation-based assays outperform traditional DNA-sequencing approaches to detecting multiple forms of cancer in blood samples," said the study's lead author, Geoffrey Oxnard, MD, of Dana-Farber. "The results of the new study demonstrate that such assays are a feasible way of screening people for cancer."
In the study, investigators analyzed cell-free DNA (DNA that had once been confined to cells but had entered the bloodstream upon the cells' death) in 3,583 blood samples, including 1,530 from patients diagnosed with cancer and 2,053 from people without cancer. The patient samples comprised more than 20 types of cancer, including hormone receptor-negative breast, colorectal, esophageal, gallbladder, gastric, head and neck, lung, lymphoid leukemia, multiple myeloma, ovarian, and pancreatic cancer.
The overall specificity was 99.4%, meaning only 0.6% of the results incorrectly indicated that cancer was present. The sensitivity of the assay for detecting a pre-specified high mortality cancers (the percent of blood samples from these patients that tested positive for cancer) was 76%. Within this group, the sensitivity was 32% for patients with stage I cancer; 76% for those with stage II; 85% for stage III; and 93% for stage IV. Sensitivity across all cancer types was 55%, with similar increases in detection by stage. For the 97% of samples that returned a tissue of origin result, the test correctly identified the organ or tissue of origin in 89% of cases.
Read more at Science Daily
Your energy-efficient washing machine could be harboring pathogens
For the first time ever, investigators have identified a washing machine as a reservoir of multidrug-resistant pathogens. The pathogens, a single clone of Klebsiella oxytoca, were transmitted repeatedly to newborns in a neonatal intensive care unit at a German children's hospital. The transmission was stopped only when the washing machine was removed from the hospital. The research is published this week in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.
"This is a highly unusual case for a hospital, in that it involved a household type washing machine," said first author Ricarda M. Schmithausen, PhD. Hospitals normally use special washing machines and laundry processes that wash at high temperatures and with disinfectants, according to the German hospital hygiene guidelines, or they use designated external laundries.
The research has implications for household use of washers, said Dr. Schmithausen, Senior Physician, Institute for Hygiene and Public Health, WHO Collaboration Center, University Hospital, University of Bonn, Germany. Water temperatures used in home washers have been declining, to save energy, to well below 60°C (140°F), rendering them less lethal to pathogens. Resistance genes, as well as different microorganisms, can persist in domestic washing machines at those reduced temperatures, according to the report.
"If elderly people requiring nursing care with open wounds or bladder catheters, or younger people with suppurating injuries or infections live in the household, laundry should be washed at higher temperatures, or with efficient disinfectants, to avoid transmission of dangerous pathogens," said Martin Exner, MD, Chairman and Director of the Institute for Hygiene and Public Health, WHO Collaboration Center, University Hospital/University of Bonn. "This is a growing challenge for hygienists, as the number of people receiving nursing care from family members is constantly increasing."
At the hospital where the washing machine transmitted K. oxytoca, standard screening procedures revealed the presence of the pathogens on infants in the ICU. The researchers ultimately traced the source of the pathogens to the washing machine, after they had failed to find contamination in the incubators or to find carriers among healthcare workers who came into contact with the infants.
The newborns were in the ICU due mostly to premature birth or unrelated infection.The clothes that transmitted K. oxytoca from the washer to the infants were knitted caps and socks to help keep them warm in incubators, as newborns can quickly become cold, even in incubators, said Dr. Exner.
The investigators assume that the pathogens "were disseminated to the clothing after the washing process, via residual water on the rubber mantle [of the washer] and/or via the final rinsing process, which ran unheated and detergent-free water through the detergent compartment," implicating the design of the washers, as well as the low heat, according to the report. The study implies that changes in washing machine design and processing are required to prevent the accumulation of residual water where microbial growth can occur and contaminate clothes.
However, it still remains unclear how, and via what source the pathogens got into the washing machine.
The infants in the intensive care units (ICU) were colonized, but not infected by K. oxytoca. Colonization means that pathogens are harmlessly present, either because they have not yet invaded tissues where they can cause disease, or because the immune system is effectively repelling them.
Read more at Science Daily
"This is a highly unusual case for a hospital, in that it involved a household type washing machine," said first author Ricarda M. Schmithausen, PhD. Hospitals normally use special washing machines and laundry processes that wash at high temperatures and with disinfectants, according to the German hospital hygiene guidelines, or they use designated external laundries.
The research has implications for household use of washers, said Dr. Schmithausen, Senior Physician, Institute for Hygiene and Public Health, WHO Collaboration Center, University Hospital, University of Bonn, Germany. Water temperatures used in home washers have been declining, to save energy, to well below 60°C (140°F), rendering them less lethal to pathogens. Resistance genes, as well as different microorganisms, can persist in domestic washing machines at those reduced temperatures, according to the report.
"If elderly people requiring nursing care with open wounds or bladder catheters, or younger people with suppurating injuries or infections live in the household, laundry should be washed at higher temperatures, or with efficient disinfectants, to avoid transmission of dangerous pathogens," said Martin Exner, MD, Chairman and Director of the Institute for Hygiene and Public Health, WHO Collaboration Center, University Hospital/University of Bonn. "This is a growing challenge for hygienists, as the number of people receiving nursing care from family members is constantly increasing."
At the hospital where the washing machine transmitted K. oxytoca, standard screening procedures revealed the presence of the pathogens on infants in the ICU. The researchers ultimately traced the source of the pathogens to the washing machine, after they had failed to find contamination in the incubators or to find carriers among healthcare workers who came into contact with the infants.
The newborns were in the ICU due mostly to premature birth or unrelated infection.The clothes that transmitted K. oxytoca from the washer to the infants were knitted caps and socks to help keep them warm in incubators, as newborns can quickly become cold, even in incubators, said Dr. Exner.
The investigators assume that the pathogens "were disseminated to the clothing after the washing process, via residual water on the rubber mantle [of the washer] and/or via the final rinsing process, which ran unheated and detergent-free water through the detergent compartment," implicating the design of the washers, as well as the low heat, according to the report. The study implies that changes in washing machine design and processing are required to prevent the accumulation of residual water where microbial growth can occur and contaminate clothes.
However, it still remains unclear how, and via what source the pathogens got into the washing machine.
The infants in the intensive care units (ICU) were colonized, but not infected by K. oxytoca. Colonization means that pathogens are harmlessly present, either because they have not yet invaded tissues where they can cause disease, or because the immune system is effectively repelling them.
Read more at Science Daily
Sep 27, 2019
Many gas giant exoplanets waiting to be discovered
There is an as-yet-unseen population of Jupiter-like planets orbiting nearby Sun-like stars, awaiting discovery by future missions like NASA's WFIRST space telescope, according to new models of gas giant planet formation by Carnegie's Alan Boss, described in an upcoming publication in The Astrophysical Journal. His models are supported by a new Science paper on the surprising discovery of a gas giant planet orbiting a low-mass star.
"Astronomers have struck a bonanza in searching for and detecting exoplanets of every size and stripe since the first confirmed exoplanet, a hot Jupiter, was discovered in 1995," Boss explained. "Literally thousands upon thousands have been found to date, with masses ranging from less than that of Earth, to many times the mass of Jupiter."
But there are still gaping holes in scientists' knowledge about exoplanets that orbit their stars at distances similar to those at which our Solar System's gas giants orbit the Sun. In terms of mass and orbital period, planets like Jupiter represent a particularly small population of the known exoplanets, but it's not yet clear if this is due to biases in the observational techniques used to find them -- which favor planets with short-period-orbits over those with long-period-orbits -- or if this represents an actual deficit in exoplanet demographics.
All the recent exoplanet discoveries have led to a renewed focus on theoretical planet formation models. Two primary mechanisms exist for predicting how gas giant planets form from the rotating disk of gas and dust that surrounds a young star -- bottom-up, called core accretion, and top-down, called disk instability.
The former refers to slowly building a planet through the collisions of increasingly larger material -- solid dust grains, pebbles, boulders, and eventually planetesimals. The latter refers to a rapidly triggered process that occurs when the disk is massive and cool enough to form spiral arms and then dense clumps of self-gravitating gas and dust contract and coalesce into a baby planet.
While core accretion is considered the consensus planet-formation mechanism, Boss has long been a proponent of the competing disk instability mechanism, dating back to a seminal 1997 Science paper.
The just-published discovery by an Institute for Space Studies of Catalonia-led team of a star that's a tenth the mass of our Sun and hosts at least one gas giant planet is challenging the core-accretion method.
The mass of a disk should be proportional to the mass of the young star around which it rotates. The fact that at least one gas giant -- possibly two -- was found around a star that's so much smaller than our Sun indicates that either the original disk was enormous, or that core accretion does not work in this system. Orbital periods for lower mass stars are longer, which prevents core accretion from forming gas giants before the disk gas disappears, as core accretion is a much slower process than disk instability, according to Boss.
"It's a great vindication for the disk instability method and a demonstration how one unusual discovery can swing the pendulum on our understanding of how planets form," said one of the IEEC research team's members, Guillem Anglada-Escudé, himself a former Carnegie postdoc.
Boss' latest simulations follow the three-dimensional evolution of hot disks that start out in a stable configuration. On a variety of time scales, these disks cool down and form spiral arms, eventually resulting in dense clumps representing newborn protoplanets. Their masses and distances from the host star are similar to that of Jupiter and Saturn.
Read more at Science Daily
"Astronomers have struck a bonanza in searching for and detecting exoplanets of every size and stripe since the first confirmed exoplanet, a hot Jupiter, was discovered in 1995," Boss explained. "Literally thousands upon thousands have been found to date, with masses ranging from less than that of Earth, to many times the mass of Jupiter."
But there are still gaping holes in scientists' knowledge about exoplanets that orbit their stars at distances similar to those at which our Solar System's gas giants orbit the Sun. In terms of mass and orbital period, planets like Jupiter represent a particularly small population of the known exoplanets, but it's not yet clear if this is due to biases in the observational techniques used to find them -- which favor planets with short-period-orbits over those with long-period-orbits -- or if this represents an actual deficit in exoplanet demographics.
All the recent exoplanet discoveries have led to a renewed focus on theoretical planet formation models. Two primary mechanisms exist for predicting how gas giant planets form from the rotating disk of gas and dust that surrounds a young star -- bottom-up, called core accretion, and top-down, called disk instability.
The former refers to slowly building a planet through the collisions of increasingly larger material -- solid dust grains, pebbles, boulders, and eventually planetesimals. The latter refers to a rapidly triggered process that occurs when the disk is massive and cool enough to form spiral arms and then dense clumps of self-gravitating gas and dust contract and coalesce into a baby planet.
While core accretion is considered the consensus planet-formation mechanism, Boss has long been a proponent of the competing disk instability mechanism, dating back to a seminal 1997 Science paper.
The just-published discovery by an Institute for Space Studies of Catalonia-led team of a star that's a tenth the mass of our Sun and hosts at least one gas giant planet is challenging the core-accretion method.
The mass of a disk should be proportional to the mass of the young star around which it rotates. The fact that at least one gas giant -- possibly two -- was found around a star that's so much smaller than our Sun indicates that either the original disk was enormous, or that core accretion does not work in this system. Orbital periods for lower mass stars are longer, which prevents core accretion from forming gas giants before the disk gas disappears, as core accretion is a much slower process than disk instability, according to Boss.
"It's a great vindication for the disk instability method and a demonstration how one unusual discovery can swing the pendulum on our understanding of how planets form," said one of the IEEC research team's members, Guillem Anglada-Escudé, himself a former Carnegie postdoc.
Boss' latest simulations follow the three-dimensional evolution of hot disks that start out in a stable configuration. On a variety of time scales, these disks cool down and form spiral arms, eventually resulting in dense clumps representing newborn protoplanets. Their masses and distances from the host star are similar to that of Jupiter and Saturn.
Read more at Science Daily
Anxiety disorders linked to disturbances in the cells' powerhouses
The powerhouse of the cell, the mitochondria, provides energy for cellular functions. But those activities can become disturbed when chronic stress leads to anxiety symptoms in mice and humans. Iiris Hovatta of the University of Helsinki and colleagues report these findings in a new study published 26th September in PLOS Genetics.
Chronic stress due to stressful life events, such as divorce, unemployment, loss of a loved one and war, are a major risk factor for developing panic attacks and anxiety disorders. Not all people who experience stressful life events go on to develop a disorder, however, and scientists are trying to identify the pathways that lead some people to be resilient to stress, while others become vulnerable to anxiety. In the current study, researchers studied mice that developed symptoms of anxiety and depression, such as avoiding social interactions, after being exposed to high levels of stress. Using a multi-pronged approach, they tracked changes in gene activity and protein production in a key region of the brain for stress-response and anxiety. The analysis pointed to a number of changes in the mitochondria in the brain cells of mice exposed to frequent stress, compared to the non-stressed mice. Furthermore, testing of blood samples collected from patients with panic disorder after a panic attack also showed differences in mitochondrial pathways, suggesting that changes to cellular energy metabolism may be a common way that animals respond to stress.
The discovery that high levels of stress may substantially impact the functioning of the powerhouses of the cell opens up new avenues of research into stress-related diseases. "Very little is known about how chronic stress may affect cellular energy metabolism and thereby influence anxiety symptoms," said author Iiris Hovatta. "The underlying mechanisms may offer a key to new targets for therapeutic interventions of stress-related diseases."
Further studies of what causes these changes to the mitochondria may provide much needed insight into the molecular basis of panic disorder and other anxiety disorders. This is a critical step in developing better therapies to treat anxiety.
From Science Daily
Chronic stress due to stressful life events, such as divorce, unemployment, loss of a loved one and war, are a major risk factor for developing panic attacks and anxiety disorders. Not all people who experience stressful life events go on to develop a disorder, however, and scientists are trying to identify the pathways that lead some people to be resilient to stress, while others become vulnerable to anxiety. In the current study, researchers studied mice that developed symptoms of anxiety and depression, such as avoiding social interactions, after being exposed to high levels of stress. Using a multi-pronged approach, they tracked changes in gene activity and protein production in a key region of the brain for stress-response and anxiety. The analysis pointed to a number of changes in the mitochondria in the brain cells of mice exposed to frequent stress, compared to the non-stressed mice. Furthermore, testing of blood samples collected from patients with panic disorder after a panic attack also showed differences in mitochondrial pathways, suggesting that changes to cellular energy metabolism may be a common way that animals respond to stress.
The discovery that high levels of stress may substantially impact the functioning of the powerhouses of the cell opens up new avenues of research into stress-related diseases. "Very little is known about how chronic stress may affect cellular energy metabolism and thereby influence anxiety symptoms," said author Iiris Hovatta. "The underlying mechanisms may offer a key to new targets for therapeutic interventions of stress-related diseases."
Further studies of what causes these changes to the mitochondria may provide much needed insight into the molecular basis of panic disorder and other anxiety disorders. This is a critical step in developing better therapies to treat anxiety.
From Science Daily
Sleep varies by age, geographical location and gender
In an exceptionally extensive worldwide study on sleep, nearly a quarter of a million nights of sleep were measured among sleepers ranging between 16 and 30 years of age.
The findings indicate that there are differences in the duration and timing of sleep by age, geographical region and gender. The timing of sleep was delayed among 16-24-year-old subjects, but in older subjects sleep was again timed earlier.
"It was interesting to find that the circadian rhythm shifts later even in people over 20 years of age. It was already previously known that sleep timing is delayed in adolescence. What was clearly highlighted in this study is how long into adulthood this actually carries on," says Liisa Kuula, a postdoctoral researcher at the University of Helsinki.
People in Europe and North America slept the longest, while the shortest sleep was observed in Asian countries. Sleep was timed the latest in the Middle East, while the earliest sleep rhythm was found in Oceania.
Young women slept more than young men, and the former also went to sleep earlier.
"Geographical differences were relatively small but similar to those seen in prior, smaller-scale studies. The need for sleep does not vary greatly between cultures, but differences arise in terms of the time reserved for sleeping," Kuula notes.
In the study, published in the Sleep Medicine journal, the sleeping habits of more than 17,000 adolescents and young adults were monitored for two weeks. The monitoring was carried out with the help of Polar Electro devices worn by the study subjects, measuring sleep with accelerometers, among other technologies. The subjects gave consent for using their personal data for research purposes, with the data being processed in anonymised form.
"We gained an exceptionally diverse and extensive dataset which provides important basic knowledge on sleep among different age groups across the globe. Validated consumer devices may hold the potential for investigations more comprehensive than those conducted with conventional data collection methods," Kuula says.
From Science Daily
The findings indicate that there are differences in the duration and timing of sleep by age, geographical region and gender. The timing of sleep was delayed among 16-24-year-old subjects, but in older subjects sleep was again timed earlier.
"It was interesting to find that the circadian rhythm shifts later even in people over 20 years of age. It was already previously known that sleep timing is delayed in adolescence. What was clearly highlighted in this study is how long into adulthood this actually carries on," says Liisa Kuula, a postdoctoral researcher at the University of Helsinki.
People in Europe and North America slept the longest, while the shortest sleep was observed in Asian countries. Sleep was timed the latest in the Middle East, while the earliest sleep rhythm was found in Oceania.
Young women slept more than young men, and the former also went to sleep earlier.
"Geographical differences were relatively small but similar to those seen in prior, smaller-scale studies. The need for sleep does not vary greatly between cultures, but differences arise in terms of the time reserved for sleeping," Kuula notes.
In the study, published in the Sleep Medicine journal, the sleeping habits of more than 17,000 adolescents and young adults were monitored for two weeks. The monitoring was carried out with the help of Polar Electro devices worn by the study subjects, measuring sleep with accelerometers, among other technologies. The subjects gave consent for using their personal data for research purposes, with the data being processed in anonymised form.
"We gained an exceptionally diverse and extensive dataset which provides important basic knowledge on sleep among different age groups across the globe. Validated consumer devices may hold the potential for investigations more comprehensive than those conducted with conventional data collection methods," Kuula says.
From Science Daily
Molecule links weight gain to gut bacteria
UT Southwestern researchers have found a key driver of the crosstalk that helps synchronize the absorption of nutrients in the gut with the rhythms of the Earth's day-night light cycle.
Their findings could have far-ranging implications for obesity in affluent countries and malnutrition in impoverished countries.
In the study, published this week by Science, Dr. Lora Hooper and her research team found that the commensal, or good, bacteria that live in the guts of mammals program the metabolic rhythms that govern the body's absorption of dietary fat. Dr. Hooper, Chair of Immunology and a Howard Hughes Medical Institute Investigator, is senior author of the study.
The study also found that microbes program these so-called circadian rhythms by activating a protein named histone deacetylase 3 (HDAC3), which is made by cells that line the gut. Those cells act as intermediaries between bacteria that aid in digestion of food and proteins that enable absorption of nutrients.
The study, done in mice, revealed that HDAC3 turns on genes involved in the absorption of fat. They found that HDAC3 interacts with the biological clock machinery within the gut to refine the rhythmic ebb and flow of proteins that enhance absorption of fat. This regulation occurs in the daytime in humans, who eat during the day, and at night in mice, which eat at night.
"The microbiome actually communicates with our metabolic machinery to make fat absorption more efficient. But when fat is overabundant, this communication can result in obesity. Whether the same thing is going on in other mammals, including humans, is the subject of future studies," added lead author Dr. Zheng Kuang, a postdoctoral fellow in the Hooper laboratory.
To go back in time, the story really starts with a few mice and crosstalk between two laboratories at UT Southwestern.
Dr. Hooper, who runs the University's colony of germ-free mice, which are raised in environments that have no microbes, is also a Professor of Immunology and Microbiology and a member of the Center for the Genetics of Host Defense. She holds the Jonathan W. Uhr, M.D. Distinguished Chair in Immunology, and is a Nancy Cain and Jeffrey A. Marcus Scholar in Medical Research, in Honor of Bill S. Vowell.
Histone modifications -- which are made by enzymes like HDAC3 -- control the expression of genes that in turn make proteins that carry out the work of the cell. Not long ago, the Hooper laboratory decided to do a mouse study of histone modifications that seemed to rise and fall along with circadian rhythms.
In comparing normal, bacteria-laden mice with germ-free ones, researchers discovered some histone modifications -- including those made by HDAC3 -- were circadian in normal mice, but held steady at a flat level in germ-free mice.
That's when Dr. Hooper contacted Dr. Eric Olson, Chair of Molecular Biology and Director of the Hamon Center for Regenerative Science and Medicine, who had done studies on HDAC3 in a different tissue, the heart. The two laboratories collaborated to develop a mouse that lacked HDAC3 only in the gut lining.
The mice they generated seemed unremarkable while eating a normal chow diet. However, when the researchers fed the mice a high fat, high sugar diet similar to one commonly consumed in the United States -- they found something very different.
"We call it the junk food diet. I describe it as like driving through a fast food restaurant for a burger and fries and then stopping off at the donut shop," she said. "Most mice on that diet become obese. To our surprise, those that had no HDAC3 in their intestinal lining were able to eat a high fat, high sugar diet and stay lean."
Next, they compared the HDAC3-deficient mice to the germ-free mice. The researchers found that both groups of mice showed the same flat, nonrhythmic histone modifications, confirming HDAC3's importance in circadian rhythms.
Every cell in the body has a molecular clock that governs bodily processes. The mouse study revealed that HDAC3 attaches to that cellular clock machinery to ensure absorption of fat is highest when mammals are awake and eating.
"Our results suggest that the microbiome and the circadian clock have evolved to work together to regulate metabolism," she said.
Why would a system evolve to make us fat? Dr. Hooper believes it could have evolved to enable mammals to use energy efficiently in order to boost immunity in an environment with food scarcity.
"This regulatory interaction probably didn't evolve to make us obese, but when combined with today's calorie-rich diets, obesity arises," she said, adding that this is speculation and the team is still working to understand all the components of the pathway.
Read more at Science Daily
Their findings could have far-ranging implications for obesity in affluent countries and malnutrition in impoverished countries.
In the study, published this week by Science, Dr. Lora Hooper and her research team found that the commensal, or good, bacteria that live in the guts of mammals program the metabolic rhythms that govern the body's absorption of dietary fat. Dr. Hooper, Chair of Immunology and a Howard Hughes Medical Institute Investigator, is senior author of the study.
The study also found that microbes program these so-called circadian rhythms by activating a protein named histone deacetylase 3 (HDAC3), which is made by cells that line the gut. Those cells act as intermediaries between bacteria that aid in digestion of food and proteins that enable absorption of nutrients.
The study, done in mice, revealed that HDAC3 turns on genes involved in the absorption of fat. They found that HDAC3 interacts with the biological clock machinery within the gut to refine the rhythmic ebb and flow of proteins that enhance absorption of fat. This regulation occurs in the daytime in humans, who eat during the day, and at night in mice, which eat at night.
"The microbiome actually communicates with our metabolic machinery to make fat absorption more efficient. But when fat is overabundant, this communication can result in obesity. Whether the same thing is going on in other mammals, including humans, is the subject of future studies," added lead author Dr. Zheng Kuang, a postdoctoral fellow in the Hooper laboratory.
To go back in time, the story really starts with a few mice and crosstalk between two laboratories at UT Southwestern.
Dr. Hooper, who runs the University's colony of germ-free mice, which are raised in environments that have no microbes, is also a Professor of Immunology and Microbiology and a member of the Center for the Genetics of Host Defense. She holds the Jonathan W. Uhr, M.D. Distinguished Chair in Immunology, and is a Nancy Cain and Jeffrey A. Marcus Scholar in Medical Research, in Honor of Bill S. Vowell.
Histone modifications -- which are made by enzymes like HDAC3 -- control the expression of genes that in turn make proteins that carry out the work of the cell. Not long ago, the Hooper laboratory decided to do a mouse study of histone modifications that seemed to rise and fall along with circadian rhythms.
In comparing normal, bacteria-laden mice with germ-free ones, researchers discovered some histone modifications -- including those made by HDAC3 -- were circadian in normal mice, but held steady at a flat level in germ-free mice.
That's when Dr. Hooper contacted Dr. Eric Olson, Chair of Molecular Biology and Director of the Hamon Center for Regenerative Science and Medicine, who had done studies on HDAC3 in a different tissue, the heart. The two laboratories collaborated to develop a mouse that lacked HDAC3 only in the gut lining.
The mice they generated seemed unremarkable while eating a normal chow diet. However, when the researchers fed the mice a high fat, high sugar diet similar to one commonly consumed in the United States -- they found something very different.
"We call it the junk food diet. I describe it as like driving through a fast food restaurant for a burger and fries and then stopping off at the donut shop," she said. "Most mice on that diet become obese. To our surprise, those that had no HDAC3 in their intestinal lining were able to eat a high fat, high sugar diet and stay lean."
Next, they compared the HDAC3-deficient mice to the germ-free mice. The researchers found that both groups of mice showed the same flat, nonrhythmic histone modifications, confirming HDAC3's importance in circadian rhythms.
Every cell in the body has a molecular clock that governs bodily processes. The mouse study revealed that HDAC3 attaches to that cellular clock machinery to ensure absorption of fat is highest when mammals are awake and eating.
"Our results suggest that the microbiome and the circadian clock have evolved to work together to regulate metabolism," she said.
Why would a system evolve to make us fat? Dr. Hooper believes it could have evolved to enable mammals to use energy efficiently in order to boost immunity in an environment with food scarcity.
"This regulatory interaction probably didn't evolve to make us obese, but when combined with today's calorie-rich diets, obesity arises," she said, adding that this is speculation and the team is still working to understand all the components of the pathway.
Read more at Science Daily
Otherworldly worms with three sexes discovered in Mono Lake
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| Mono Lake, Tufa State Natural Reserve, near Lee Vining, California. |
Mono Lake, located in the Eastern Sierras of California, is three times as salty as the ocean and has an alkaline pH of 10. Before this study, only two other species (other than bacteria and algae) were known to live in the lake -- brine shrimp and diving flies. In this new work, the team discovered eight more species, all belonging to a class of microscopic worms called nematodes, thriving in and around Mono Lake.
The work was done primarily in the laboratory of Paul Sternberg, Bren Professor of Biology. A paper describing the research appears online on September 26 in the journal Current Biology.
The Sternberg laboratory has had a long interest in nematodes, particularly Caenorhabditis elegans, which uses only 300 neurons to exhibit complex behaviors, such as sleeping, learning, smelling, and moving. That simplicity makes it a useful model organism with which to study fundamental neuroscience questions. Importantly, C. elegans can easily thrive in the laboratory under normal room temperatures and pressures.
As nematodes are considered the most abundant type of animal on the planet, former Sternberg lab graduate students Pei-Yin Shih (PhD '19) and James Siho Lee (PhD '19) thought they might find them in the harsh environment of Mono Lake. The eight species they found are diverse, ranging from benign microbe-grazers to parasites and predators. Importantly, all are resilient to the arsenic-laden conditions in the lake and are thus considered extremophiles -- organisms that thrive in conditions unsuitable for most life forms.
When comparing the new Auanema species to sister species in the same genus, the researchers found that the similar species also demonstrated high arsenic resistance, even though they do not live in environments with high arsenic levels. In another surprising discovery, Auanema sp. itself was found to be able to thrive in the laboratory under normal, non-extreme conditions. Only a few known extremophiles in the world can be studied in a laboratory setting.
This suggests that nematodes may have a genetic predisposition for resiliency and flexibility in adapting to harsh and benign environments alike.
"Extremophiles can teach us so much about innovative strategies for dealing with stress," says Shih. "Our study shows we still have much to learn about how these 1000-celled animals have mastered survival in extreme environments."
The researchers plan to determine if there are particular biochemical and genetic factors that enable nematodes' success and to sequence the genome of Auanema sp. to look for genes that may enable arsenic resistance. Arsenic-contaminated drinking water is a major global health concern; understanding how eukaryotes like nematodes deal with arsenic will help answer questions about how the toxin moves through and affects cells and bodies.
But beyond human health, studying extreme species like the nematodes of Mono Lake contributes to a bigger, global picture of the planet, says Lee.
"It's tremendously important that we appreciate and develop a curiosity for biodiversity," he adds, noting that the team had to receive special permits for their field work at the lake. "The next innovation for biotechnology could be out there in the wild. A new biodegradable sunscreen, for example, was discovered from extremophilic bacteria and algae. We have to protect and responsibly utilize wildlife."
Read more at Science Daily
Sep 26, 2019
Scientists watch a black hole shredding a star
A NASA satellite searching space for new planets gave astronomers an unexpected glimpse at a black hole ripping a star to shreds.
It is one of the most detailed looks yet at the phenomenon, called a tidal disruption event (or TDE), and the first for NASA's Transiting Exoplanet Survey Satellite (more commonly called TESS.)
The milestone was reached with the help of a worldwide network of robotic telescopes headquartered at The Ohio State University called ASAS-SN (All-Sky Automated Survey for Supernovae). Astronomers from the Carnegie Observatories, Ohio State and others published their findings today in The Astrophysical Journal.
"We've been closely monitoring the regions of the sky where TESS is observing with our ASAS-SN telescopes, but we were very lucky with this event in that the patch of the sky where TESS is continuously observing is small, and in that this happened to be one of the brightest TDEs we've seen," said Patrick Vallely, a co-author of the study and National Science Foundation Graduate Research Fellow at Ohio State. "Due to the quick ASAS-SN discovery and the incredible TESS data, we were able to see this TDE much earlier than we've seen others -- it gives us some new insight into how TDEs form."
Tidal disruption events happen when a star gets too close to a black hole. Depending on a number of factors, including the size of the star, the size of the black hole and how close the star is to the black hole, the black hole can either absorb the star or tear it apart into a long, spaghetti-like strand.
"TESS data let us see exactly when this destructive event, named ASASSN-19bt, started to get brighter, which we've never been able to do before," said Thomas Holoien, a Carnegie Fellow at the Carnegie Observatories in Pasadena, California, who earned his PhD at Ohio State. "Because we discovered the tidal disruption quickly with the ground-based ASAS-SN, we were able to trigger multiwavelength follow-up observations in the first few days. The early data will be incredibly helpful for modeling the physics of these outbursts."
ASAS-SN was the first system to see that a black hole was ripping a star apart. Holoien was working at the Las Campanas Observatory in Chile on Jan. 29, 2019, when he got an alert from one of ASAS-SN's robotic telescopes in South Africa. Holoien trained two Las Campanas telescopes on the tidal disruption event and then requested follow-up observations by other telescopes around the world.
TESS already happened to be monitoring the exact part of the sky where the ASAS-SN telescope discovered the tidal disruption event. It was not just good luck that the telescopes and satellite aligned -- after TESS launched in July 2018, the team behind ASAS-SN devoted more of the ASAS-SN telescopes' time to the parts of the sky that TESS was observing.
But it was fortunate that the tidal disruption event happened in the systems' lines of sight, said Chris Kochanek, professor of astronomy at Ohio State.
Tidal disruptions are rare, occurring once every 10,000 to 100,000 years in a galaxy the size of the Milky Way. Supernovae, by comparison, happen every 100 years or so. Scientists have observed about 40 tidal disruption events throughout history (ASAS-SN sees a few per year). The events are rare, Kochanek said, mostly because stars need to be very close to a black hole -- about the distance Earth is from our own sun -- in order to create one.
"Imagine that you are standing on top of a skyscraper downtown, and you drop a marble off the top, and you are trying to get it to go down a hole in a manhole cover," he said. "It's harder than that."
And because ASAS-SN caught the tidal disruption event early, Holoien was able to train additional telescopes on the event, capturing a more detailed look than might have been possible before. Astronomers could then look at data from TESS -- which, because it came from a satellite in space, was not available until a few weeks after the event -- to see whether they could spot the event in the lead-up. Data from TESS meant that they could see signs of the tidal disruption event in data from about 10 days before it occurred.
"The early TESS data allow us to see light very close to the black hole, much closer than we've been able to see before," Vallely said. "They also show us that ASASSN-19bt's rise in brightness was very smooth, which helps us tell that the event was a tidal disruption and not another type of outburst, like from the center of a galaxy or a supernova."
Holoien's team used UV data from NASA's Neil Gehrels Swift Observatory -- the earliest yet seen from a tidal disruption -- to determine that the temperature dropped by about 50%, from around 71,500 to 35,500 degrees Fahrenheit (40,000 to 20,000 degrees Celsius), over a few days. It's the first time such an early temperature decrease has been seen in a tidal disruption before, although a few theories have predicted it, Holoien said.
More typical for these kinds of events was the low level of X-ray emission seen by Swift. Scientists don't fully understand why tidal disruptions produce so much UV emission and so few X-rays.
Read more at Science Daily
It is one of the most detailed looks yet at the phenomenon, called a tidal disruption event (or TDE), and the first for NASA's Transiting Exoplanet Survey Satellite (more commonly called TESS.)
The milestone was reached with the help of a worldwide network of robotic telescopes headquartered at The Ohio State University called ASAS-SN (All-Sky Automated Survey for Supernovae). Astronomers from the Carnegie Observatories, Ohio State and others published their findings today in The Astrophysical Journal.
"We've been closely monitoring the regions of the sky where TESS is observing with our ASAS-SN telescopes, but we were very lucky with this event in that the patch of the sky where TESS is continuously observing is small, and in that this happened to be one of the brightest TDEs we've seen," said Patrick Vallely, a co-author of the study and National Science Foundation Graduate Research Fellow at Ohio State. "Due to the quick ASAS-SN discovery and the incredible TESS data, we were able to see this TDE much earlier than we've seen others -- it gives us some new insight into how TDEs form."
Tidal disruption events happen when a star gets too close to a black hole. Depending on a number of factors, including the size of the star, the size of the black hole and how close the star is to the black hole, the black hole can either absorb the star or tear it apart into a long, spaghetti-like strand.
"TESS data let us see exactly when this destructive event, named ASASSN-19bt, started to get brighter, which we've never been able to do before," said Thomas Holoien, a Carnegie Fellow at the Carnegie Observatories in Pasadena, California, who earned his PhD at Ohio State. "Because we discovered the tidal disruption quickly with the ground-based ASAS-SN, we were able to trigger multiwavelength follow-up observations in the first few days. The early data will be incredibly helpful for modeling the physics of these outbursts."
ASAS-SN was the first system to see that a black hole was ripping a star apart. Holoien was working at the Las Campanas Observatory in Chile on Jan. 29, 2019, when he got an alert from one of ASAS-SN's robotic telescopes in South Africa. Holoien trained two Las Campanas telescopes on the tidal disruption event and then requested follow-up observations by other telescopes around the world.
TESS already happened to be monitoring the exact part of the sky where the ASAS-SN telescope discovered the tidal disruption event. It was not just good luck that the telescopes and satellite aligned -- after TESS launched in July 2018, the team behind ASAS-SN devoted more of the ASAS-SN telescopes' time to the parts of the sky that TESS was observing.
But it was fortunate that the tidal disruption event happened in the systems' lines of sight, said Chris Kochanek, professor of astronomy at Ohio State.
Tidal disruptions are rare, occurring once every 10,000 to 100,000 years in a galaxy the size of the Milky Way. Supernovae, by comparison, happen every 100 years or so. Scientists have observed about 40 tidal disruption events throughout history (ASAS-SN sees a few per year). The events are rare, Kochanek said, mostly because stars need to be very close to a black hole -- about the distance Earth is from our own sun -- in order to create one.
"Imagine that you are standing on top of a skyscraper downtown, and you drop a marble off the top, and you are trying to get it to go down a hole in a manhole cover," he said. "It's harder than that."
And because ASAS-SN caught the tidal disruption event early, Holoien was able to train additional telescopes on the event, capturing a more detailed look than might have been possible before. Astronomers could then look at data from TESS -- which, because it came from a satellite in space, was not available until a few weeks after the event -- to see whether they could spot the event in the lead-up. Data from TESS meant that they could see signs of the tidal disruption event in data from about 10 days before it occurred.
"The early TESS data allow us to see light very close to the black hole, much closer than we've been able to see before," Vallely said. "They also show us that ASASSN-19bt's rise in brightness was very smooth, which helps us tell that the event was a tidal disruption and not another type of outburst, like from the center of a galaxy or a supernova."
Holoien's team used UV data from NASA's Neil Gehrels Swift Observatory -- the earliest yet seen from a tidal disruption -- to determine that the temperature dropped by about 50%, from around 71,500 to 35,500 degrees Fahrenheit (40,000 to 20,000 degrees Celsius), over a few days. It's the first time such an early temperature decrease has been seen in a tidal disruption before, although a few theories have predicted it, Holoien said.
More typical for these kinds of events was the low level of X-ray emission seen by Swift. Scientists don't fully understand why tidal disruptions produce so much UV emission and so few X-rays.
Read more at Science Daily
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