Charred grains of barley, millet and wheat deposited nearly 5,000 years ago at campsites in the high plains of Kazakhstan show that nomadic sheepherders played a surprisingly important role in the early spread of domesticated crops throughout a mountainous east-west corridor along the historic Silk Road, suggests new research from Washington University in St. Louis.”Our findings indicate that ancient nomadic pastoralists were key players in an east-west network that linked innovations and commodities between present-day China and southwest Asia,” said study co-author Michael Frachetti, PhD, an associate professor of archaeology in Arts & Sciences at Washington University and principal investigator on the research project.”Ancient wheat and broomcorn millet, recovered in nomadic campsites in Kazakhstan, show that prehistoric herders in Central Eurasia had incorporated both regional crops into their economy and rituals nearly 5,000 years ago, pushing back the chronology of interaction along the territory of the ‘Silk Road’ more than 2,000 years,” Frachetti said.The study, to be published April 2 in the Proceedings of the Royal Society B, establishes that several strains of ancient grains and peas had made their way across Eurasia thousands of years earlier than previously documented.While these crops have been known to exist much earlier in ancient China and Southwest Asia, finding them intermingled in the Bronze Age burials and households of nomadic pastoralists provides some of the earliest concrete signs for east-west interaction in the vast expanse of Eurasian mountains and the first botanical evidence for farming among Bronze Age nomads.Bread wheat, cultivated at least 6,000 years ago in Southwest Asia, was absent in China before 2500 B.C. while broomcorn millet, domesticated 8,000 years ago in China, is missing in southwest Asia before 2000 B.C. This study documents that ancient grains from eastern China and soutwest Asia had made their way to Kazakhstan in the center of the continent by 2700-2500 B.C. (nearly 5,000 years ago).”This study starts to rewrite the model for economic change across Eurasia,” said first author Robert Spengler, PhD, a paleoethnobotanist and research associate in Arts & Sciences at WUSTL.”It illustrates that nomads had diverse economic systems and were important for reshaping economic spheres more generally.”Findings are based on archaeobotanical data collected from four Bronze Age pastoralist campsites in Central Eurasian steppe/mountains: Tasbas and Begash in the highlands of Kazakhstan and Ojakly and Site 1211/1219 in Turkmenistan.”This is one of the first systematic applications of archaeobotany in the region, making the potential for further future discovery very exciting,” Spengler said.Frachetti and a team of WUSTL researchers led the on-site excavations, working closely with archaeologists based in Turkmenistan, Kazakhstan and Italy. Spengler conducted the paleoethnobotany laboratory work at WUSTL, under the directorship of Gayle J. Fritz, PhD, professor of archaeology and expert in human-plant relationships.”Finding this diverse crop assemblage at Tasbas and Begash illustrates first evidence for the westward spread of East Asian and Southwest Asian crops eastward, and the surprise is that it is nomads who are the agents of change,” Frachetti said.Story Source:The above story is based on materials provided by Washington University in St. Louis. The original article was written by Gerry Everding. Note: Materials may be edited for content and length.Read more
There is a lot that 19-month-old children can’t do: They can’t tie their shoes or get their mittens on the correct hands. But they can use words they do know to learn new ones.New research from Northwestern University demonstrates that even before infants begin to talk in sentences, they are paying careful attention to the way a new word is used in conversations, and they learn new words from this information in sentences.For example, if you take an infant to the zoo and say, “Look at the gorilla” while pointing at the cage, the infant may not know what exactly is being referred to. However, if you say, “Look! The gorilla is eating,” the infant can use the word that they do know — “eating” — to conclude that “gorilla” must refer to the animal and not, for example, the swing she is sitting on.The zoo scenario mirrors the method the researchers used for their experiment. First, infants at ages 15 and 19 months were shown several pairs of pictures on a large screen. Each pair included one new kind of animal and a non-living object. Next, the objects disappeared from view and infants overheard a conversation that included a new word, “blick.” Finally, the two objects re-appeared, and infants heard, for example, “Look at the blick.””After overhearing this new word in conversation, infants who hear a helpful sentence such as ‘the blick is eating’ should look more towards the animal than the other, non-living object,” said Brock Ferguson, a doctoral candidate in psychology at Northwestern and lead author of the study. “We show that by 19 months, they do just that. In contrast, if infants heard the new word in an unhelpful sentence such as ‘the blick is over here’ during the conversation, they don’t focus specifically on the animal because, after all, in this kind of sentence, ‘blick’ could mean anything.”The researchers said many people believe that word learning occurs only in clear teaching conditions — for example, when someone picks up an object, brings it to the baby, points to it and says its name. In fact, infants usually hear a new word for the first time under much more natural and complex circumstances such as the zoo example described.”What’s remarkable is that infants learned so much from hearing the conversation alone,” said Sandra Waxman, senior author of the study, the Louis W. …Read more
Increased brain cell activity boosts brain fluid levels of a protein linked to Alzheimer’s disease, according to new research from scientists at Washington University School of Medicine in St. Louis.Tau protein is the main component of neurofibrillary tangles, one of the hallmarks of Alzheimer’s disease. It has been linked to other neurodegenerative disorders, including frontotemporal dementia, supranuclear palsy and corticobasal degeneration.”Healthy brain cells normally release tau into the cerebrospinal fluid and the interstitial fluid that surrounds them, but this is the first time we’ve linked that release in living animals to brain cell activity,” said senior author David M. Holtzman, MD. “Understanding this link should help advance our efforts to treat Alzheimer’s and other neurodegenerative disorders associated with the tau protein.The study appears online in The Journal of Experimental Medicine.Tau protein stabilizes microtubules, which are long columns that transport supplies from the center of the cell to the distant ends of the cell’s branches. Some tau in the cell is not bound to microtubules. This tau can become altered and clump together inside brain cells, forming structures called tangles. Scientists have tracked the spread of these clumps through brain networks in animal models.”In Alzheimer’s disease, you first see clumps of tau in a region called the entorhinal cortex, and then in the hippocampus, and it continues to spread through the brain in a regular pattern,” said Holtzman, the Andrew B. and Gretchen P. Jones Professor and head of the Department of Neurology. …Read more
Health professionals who treat people with psychiatric problems often overlook their patients’ smoking habits, assuming it’s best to tackle depression, anxiety or substance abuse problems first. However, new research at Washington University School of Medicine in St. Louis shows that people who struggle with mood problems or addiction can safely quit smoking and that kicking the habit is associated with improved mental health.The study is published online in the journal Psychological Medicine.”Clinicians tend to treat the depression, alcohol dependence or drug problem first and allow patients to ‘self-medicate’ with cigarettes if necessary,” said lead investigator Patricia A. Cavazos-Rehg, PhD. “The assumption is that psychiatric problems are more challenging to treat and that quitting smoking may interfere with treatment.”But in the study, Cavazos-Rehg, an assistant professor of psychiatry, found that quitting or significantly cutting back on cigarette smoking was linked to improved mental health outcomes. Quitting altogether or reducing by half the number of cigarettes smoked daily was associated with lower risk for mood disorders like depression, as well as a lower likelihood of alcohol and drug problems.”We don’t know if their mental health improves first and then they are more motivated to quit smoking or if quitting smoking leads to an improvement in mental health,” Cavazos-Rehg said. “But either way, our findings show a strong link between quitting and a better psychiatric outlook.”In addition, she believes the serious health risks associated with smoking make it important for doctors to work with their patients to quit, regardless of other psychiatric problems.”About half of all smokers die from emphysema, cancer or other problems related to smoking, so we need to remember that as complicated as it can be to treat mental health issues, smoking cigarettes also causes very serious illnesses that can lead to death,” she explained.Cavazos-Rehg and her team analyzed questionnaires gathered as part of the National Epidemiologic Study on Alcohol and Related Conditions. In the early 2000s, just under 35,000 people were surveyed. As part of the study, they answered questions about drinking, smoking and mental health in two interviews conducted three years apart.The researchers focused on data from 4,800 daily smokers. Those who had addiction or other psychiatric problems at the time of the first survey were less likely to have those same problems three years later if they had quit smoking. …Read more
Researchers at Washington University School of Medicine in St. Louis have demonstrated a new approach to treating muscular dystrophy. Mice with a form of this muscle-weakening disease showed improved strength and heart function when treated with nanoparticles loaded with rapamycin, an immunosuppressive drug recently found to improve recycling of cellular waste.The study appears online in The FASEB Journal.The investigators, including first author Kristin P. Bibee, MD, PhD, looked at a mouse model of Duchenne muscular dystrophy, the most severe inherited form of the disease. Duchenne exclusively affects boys who have to rely on wheelchairs by age 12 and die from heart or respiratory failure in their 20s.The faulty gene that causes the disease prevents the body from producing dystrophin, a protein crucial for maintaining muscle cell integrity and function. The new study demonstrated that mice with muscular dystrophy, in addition to missing dystrophin, also can’t recycle cellular waste, a process known as autophagy, or self-eating.”Autophagy plays a major role in disposing of cellular debris,” said senior author Samuel A. Wickline, MD, the James R. Hornsby Family Professor of Medicine. “If it doesn’t happen, you might say the cell chokes on its own refuse. In muscular dystrophy, defective autophagy is not necessarily a primary source of muscle weakness, but it clearly becomes a problem over time. …Read more
Scientists have for the first time sequenced an ancient RNA genome — of a barley virus once believed to be only 150 years old — pushing its origin back at least 2,000 years and revealing how intense farming at the time of the Crusades contributed to its spread.Researchers at the University of Warwick have detected and sequenced the RNA genome of Barley Stripe Mosaic Virus (BSMV) in a 750-year-old barley grain found at a site near the River Nile in modern-day Egypt. Their study is published in the journal Scientific Reports.This new find challenges current beliefs about the age of the BSMV virus, which was first discovered in 1950 with the earliest record of symptoms just 100 years ago.Although ancient DNA genomes have been sequenced before, ancient RNA genomes have not been as RNA breaks down more rapidly than DNA — generally around 50 times as fast.However in extremely dry conditions, such as those at the site in Qasr Ibrim in Lower Nubia where the barley was found, RNA can be better preserved and this has allowed the scientists to successfully sequence its genome.Using the new medieval RNA to calibrate estimates of the rate of mutations, the researchers were able to trace the evolution of the Barley Stripe Mosaic Virus to a probable origin of around 2,000 years ago, but potentially much further back to the domestication of barley in the Near East around 11,000 years ago.BSMV is transmitted through seed-to-seed contact so it is likely to originally have been transferred from the wild grass population to an early cultivated form of barley while the seeds were stored.Dr Robin Allaby of the School of Life Sciences at the University of Warwick, who led the study, said: “It is important to know as much as we can about virus evolution as emerging infectious plant diseases are a growing threat to global food security, and of those viruses account for almost half.”History tells us about the devastation caused by the emergence of disease from wild hosts in disparate countries, such as the Central American origin of the oomycete that led to the Irish potato famine.”We need to build up an accurate picture of the evolution of different types of virus so we can make better decisions about policies on plant movement.”The medieval RNA from Qasr Ibrim gives us a vital clue to unlock the real age of the Barley Stripe Mosaic Virus.”It is very difficult to understand how a plant disease evolved by solely relying on recent samples, however this 750-year-old example of the virus allows us to more accurately estimate its evolution rates and date of origin.”Without the Medieval RNA evidence, the virus appears to be much younger than it actually is, when in fact its origins go back thousands of years.”It’s possible that other viruses that similarly appear to be very recent may in fact have a more ancient origin.”The researchers believe that the Medieval BSMV genome came from a time of rapid expansion of the plant disease in the Near East and Europe.This coincided with the tumult of the Crusades which saw the Christian lands of Europe take arms against the Muslim territories of the Near East with their sights set on the city of Jerusalem. The seventh Crusade of Louis IX in 1234 is the most closely aligned in date to the origin of the virus expansion.The researchers believe the massive war effort could have caused the virus to spread, fuelled by an intensification of farming in order to feed the armies engaged in the campaign.This made contact with cultivated barley and wild grass more likely, providing opportunities for the virus to ‘jump’ into the crop.Genetic evidence also points to a split into an east and west BSMV lineage around the end of the 15th century, around 100 years after the Mongol Empire stabilised the Silk Road. It is likely that BSMV was transported to the east via trade routes such as the Silk Road in the late Medieval period.In more recent history, the virus appears to have spread to the US from Europe around 120-150 years ago.The research was supported by the research funding body BBSRC.Story Source:The above story is based on materials provided by University of Warwick. Note: Materials may be edited for content and length.Read more
Scientists have identified a way some viruses protect themselves from the immune system’s efforts to stop infections, a finding that may make new approaches to treating viral infections possible.Viruses have well-known strategies for slipping past the immune system. These include faking or stealing a molecular identification badge that prevents a cell from recognizing a virus.Scientists at Washington University School of Medicine in St. Louis and elsewhere have found some viruses have another trick. They can block the immune system protein that checks for the identification badge.The blocking structure is called a stem-loop, found at the beginning of the virus’s genetic material. This is the first time scientists have found an immune-fighting mechanism built directly into the genetic material of a virus. They are looking for ways to disable it and searching for similar mechanisms that may be built into the genetic material of other disease-causing microorganisms.”When the stem-loop is in place and stable, it blocks a host cell immune protein that otherwise would bind to the virus and stop the infectious process,” said senior author Michael Diamond, MD, PhD, professor of medicine. “We found that changing a single letter of the virus’s genetic code can disable the stem-loop’s protective effects and allow the virus to be recognized by the host immune protein. We hope to find ways to weaken the stem-loop structure with drugs or other treatments, restoring the natural virus-fighting capabilities of the cell and stopping or slowing some viral infections.”Most life forms encode their genes in DNA. To use the instructions contained in DNA, though, cells have to translate them into a related genetic material, RNA, that can be read by a cell’s protein-making machinery.Some viruses encode their genes directly in RNA. Examples include West Nile virus and influenza virus, and the viruses that cause sudden acute respiratory syndrome (SARS), yellow fever and polio.When a virus infects a cell, it co-opts the cell’s protein-making machinery to make viral proteins. …Read more
Oct. 16, 2013 — Examining 12 major types of cancer, scientists at Washington University School of Medicine in St. Louis have identified 127 repeatedly mutated genes that appear to drive the development and progression of a range of tumors in the body. The discovery sets the stage for devising new diagnostic tools and more personalized cancer treatments.The research, published Oct. 17 in Nature, shows that some of the same genes commonly mutated in certain cancers also occur in seemingly unrelated tumors. For example, a gene mutated in 25 percent of leukemia cases in the study also was found in tumors of the breast, rectum, head and neck, kidney, lung, ovary and uterus.Based on the findings, the researchers envision that a single test that surveys errors in a swath of cancer genes eventually could become part of the standard diagnostic workup for most cancers. Results of such testing could guide treatment decisions for patients based on the unique genetic signatures of their tumors.New insights into cancer are possible because of advances in genome sequencing that enable scientists to analyze the DNA of cancer cells on a scale that is much faster and less expensive today than even a few years ago. While earlier genome studies typically have focused on individual tumor types, the current research is one of the first to look across many different types of cancer.”This is just the beginning,” said senior author Li Ding, PhD, of The Genome Institute at Washington University. “Many oncologists and scientists have wondered whether it’s possible to come up with a complete list of cancer genes responsible for all human cancers. I think we’re getting closer to that.”The new research analyzed the genes from 3,281 tumors — a collection of cancers of the breast, uterus, head and neck, colon and rectum, bladder, kidney, ovary, lung, brain and blood. …Read more
Oct. 10, 2013 — The city of Providence, R.I., is taking the fight against Big Tobacco to a new level with innovative tobacco control policies. A new study, led in part by Washington University in St. Louis’ Center for Public Health Systems Science (CPHSS), details Providence’s efforts and provides a road map for other municipalities to follow.”Tobacco companies spend an overwhelming majority of their annual marketing budget at the point of sale, an area that has not been regulated,” said Douglas A. Luke, PhD, professor at the Brown School, director of the center and principal investigator on the case study. “Providence was one of the first cities in the United States to pass ordinances to regulate price discounting and coupon redemption, and now the courts are weighing in favorably.”This is a great public health victory,” he said.In February 2012, Providence passed ordinances that cracked down on two tactics — sweet flavors and price discounts — used by tobacco companies to lure kids. The ordinances survived two challenges in court, most recently by the 1st U.S. Circuit Court of Appeals on Sept. 30 that affirmed a December 2012 ruling from a U.S. district court.The CPHSS case study, “Regulating Price Discounting in Providence, R.I.” provides in-depth information about the process that Providence took to successfully develop and implement its ordinance.”The recent court ruling has implications for other states and communities that would like to pass similar policies,” said Amy Sorg, project coordinator at CPHSS and lead author of the case study. …Read more
Sep. 4, 2013 — Scientists at Rice University have trapped bismuth in a nanotube cage to tag stem cells for X-ray tracking.Bismuth is probably best known as the active element in a popular stomach-settling elixir and is also used in cosmetics and medical applications. Rice chemist Lon Wilson and his colleagues are inserting bismuth compounds into single-walled carbon nanotubes to make a more effective contrast agent for computed tomography (CT) scanners.Details of the work by Wilson’s Rice team and collaborators at the University of Houston, St. Luke’s Episcopal Hospital, and the Texas Heart Institute appear in the Journal of Materials Chemistry B.This is not the first time bismuth has been tested for CT scans, and Wilson’s lab has been experimenting for years with nanotube-based contrast agents for magnetic resonance imaging (MRI) scanners. But this is the first time anyone has combined bismuth with nanotubes to image individual cells, he said.”At some point, we realized no one has ever tracked stem cells, or any other cells that we can find, by CT,” Wilson said. “CT is much faster, cheaper and more convenient, and the instrumentation is much more widespread (than MRI). So we thought if we put bismuth inside the nanotubes and the nanotubes inside stem cells, we might be able to track them in vivo in real time.”Experiments to date confirm their theory. In tests using pig bone marrow-derived mesenchymal stem cells, Wilson and lead author Eladio Rivera, a former postdoctoral researcher at Rice, found that the bismuth-filled nanotubes, which they call Bi@US-tubes, produce CT images far brighter than those from common iodine-based contrast agents.”Bismuth has been thought of before as a CT contrast agent, but putting it in nanotube capsules allows us to get them inside cells in high concentrations,” Wilson said. “That lets us take an X-ray image of the cell.”The capsules are made from a chemical process that cuts and purifies the nanotubes. When the tubes and bismuth chloride are mixed in a solution, they combine over time to form Bi@US-tubes.The nanotube capsules are between 20 and 80 nanometers long and about 1.4 nanometers in diameter. …Read more
Aug. 15, 2013 — You plan on shopping for groceries later and you tell yourself that you have to remember to take the grocery bags with you when you leave the house. Lo and behold, you reach the check-out counter and you realize you’ve forgotten the bags.Remembering to remember — whether it’s grocery bags, appointments, or taking medications — is essential to our everyday lives. New research sheds light on two distinct brain processes that underlie this type of memory, known as prospective memory.The research is published in Psychological Science, a journal of the Association for Psychological Science.To investigate how prospective memory is processed in the brain, psychological scientist Mark McDaniel of Washington University in St. Louis and colleagues had participants lie in an fMRI scanner and asked them to press one of two buttons to indicate whether a word that popped up on a screen was a member of a designated category. In addition to this ongoing activity, participants were asked to try to remember to press a third button whenever a special target popped up. The task was designed to tap into participants’ prospective memory, or their ability to remember to take certain actions in response to specific future events.When McDaniel and colleagues analyzed the fMRI data, they observed that two distinct brain activation patterns emerged when participants made the correct button press for a special target.When the special target was not relevant to the ongoing activity — such as a syllable like “tor” — participants seemed to rely on top-down brain processes supported by the prefrontal cortex. In order to answer correctly when the special syllable flashed up on the screen, the participants had to sustain their attention and monitor for the special syllable throughout the entire task. In the grocery bag scenario, this would be like remembering to bring the grocery bags by constantly reminding yourself that you can’t forget them.When the special target was integral to the ongoing activity — such as a whole word, like “table” — participants recruited a different set of brain regions, and they didn’t show sustained activation in these regions. The findings suggest that remembering what to do when the special target was a whole word didn’t require the same type of top-down monitoring. …Read more
Aug. 6, 2013 — Frozen sperm taken by biopsy from testicles in men with no sperm in their semen is as effective as fresh sperm taken by biopsy in helping couples conceive through in vitro fertilization (IVF), according to a study at Washington University School of Medicine in St. Louis.The researchers also determined that the type of facility where sperm is taken and its distance from the IVF laboratory has no bearing on pregnancy outcomes.The findings, published online in PLOS ONE, may benefit men with no sperm in their semen due to genetics, cancer diagnoses or testicular failure. These men do not have enough sperm to have their own children through IVF without being biopsied.In these men, a biopsy in a testicle often results in enough sperm to be used in a procedure called intracytoplasmic sperm injection (ICSI) as part of the IVF process in men with severe infertility.The biopsy, which is usually performed on an outpatient basis, involves obtaining tissue from testicles that is examined for sperm. If sperm are found, they are removed and used immediately in ICSI or frozen for future use.In ICSI, a single sperm is injected into an egg that has been surgically retrieved from a woman’s ovaries. The fertilized egg, or embryo, then is transferred to the woman’s womb.“The convenience and ease of being able to use frozen sperm taken by biopsy in ICSI offers many advantages over fresh sperm,” said Kenan Omurtag, MD, the study’s first author and assistant professor of obstetrics and gynecology.“When fresh sperm is used, the biopsy for the sperm retrieval needs to be done the day before or on the same day as egg retrieval from the woman, and this may not be convenient for the couple. When frozen sperm is used, the man can have his biopsy first, and if sperm is found, it can be banked. Then, at the couple’s convenience, the woman’s eggs are retrieved and ICSI can be completed.Before ICSI, a woman takes daily injections of fertility medications for a week to 10 days to stimulate her ovaries to produce eggs. Using an ultrasound to locate eggs, a doctor then removes them from the woman’s ovaries with a fine, hollow needle.In this study, researchers analyzed data from 1995 through 2009 from the Washington University Infertility and Reproductive Medicine Center.One hundred thirty-six men had testicular biopsies to be used in ICSI. Of those biopsies, 84 percent involved frozen sperm and the remaining 16 percent used fresh sperm. …Read more
July 31, 2013 — In a retrospective study, Saint Louis University researchers have found that patients with melanoma brain metastases can be treated with large doses of interleukin-2 (HD IL-2), a therapy that triggers the body’s own immune system to destroy the cancer cells.The study that was recently published in Chemotherapy Research and Practice, reviews cases of eight patients who underwent this therapy at Saint Louis University.John Richart, M.D., associate professor of internal medicine at SLU and principal investigator of the study, first treated a patient with the disease using the HD IL-2 treatment in 1999.”Traditionally, melanoma patients with brain metastases have not been considered for HD IL-2 because treatment was thought to be futile,” Richart said. “Our study shows that having this condition does not exclude a patient from getting this treatment and can in fact improve the length of their life.”Melanoma is the most dangerous form of skin cancer that begins in the melanin-producing cells called melanocytes. In some melanoma patients, the cancer spreads to the brain, causing multiple tumors that are difficult to treat. According to the CDC, melanoma is the third most common cancer causing brain metastases in the U.S. Richart said the median overall survival of patients with melanoma brain metastases is approximately four months whereas in the study, the median overall survival for patients was 8.7 months.During the treatment, patients are given an IV medication — a chemical the body naturally makes that stimulates the immune system to recognize and destroy melanoma cells — for a period of six days while they are admitted to the hospital and are closely monitored by doctors and nurses. A patient requires four such six-day admission cycles in order to complete the course of the treatment.To be eligible for HD IL-2 treatment, melanoma patients with brain metastases have to be in healthy shape with good brain function — that is they cannot have brain lesions that are growing rapidly or show any symptoms of brain lesions. In the past, melanoma patients with brain metastases have been considered ineligible for this treatment because doctors thought that the treatment would cause life-threatening cerebral edema, a complication that causes excess accumulation of fluids in the brain, and neurotoxicity, or irreversible damage to the brain or the nervous system.”In this review, we found that there were no episodes of treatment-related mortality. Our findings demonstrate that HD IL-2 can be considered as an option for patients with melanoma brain metastases,” said Melinda Chu, M.D., a first year dermatology resident at SLU and first author of the study. SLU is the only medical center in the region that provides this treatment.”We need a highly skilled nursing staff for the HD-IL-2 program to be successful,” Richart said. “Our nursing team at SLU is with each patient every step of the way, 24 hours a day. …Read more
July 29, 2013 — In 2011, Nature announced that scientists had discovered a single-celled organism that is a primitive farmer. The organism, a social amoeba called Dictyostelium discoideum, picks up edible bacteria, carries them to new locations and harvests them like crops.D. discoideum enjoyed a brief spell in the media spotlight, billed as the world’s smallest farmer.Now a collaboration of scientists at Washington University in St. Louis and Harvard University has taken a closer look at one lineage, or clone, of a D. discoideum farmer.This farmer carries not one but two strains of bacteria. One strain is the “seed corn” for a crop of edible bacteria, and the other strain is a weapon that produces defensive chemicals.The edible bacteria, the scientists found, evolved from the toxic one. The two strains differ by many mutations but a single key mutation, which hit an important controller in the genome of the nonfood strain, alters expression of 10 percent of its genome. This alteration increases the expression of some genes and decreases the expression of others.A mutation that affects this much of a genome could be lethal, but in this case it had the surprising effect of making the bacterium edible by changing its chemical profile.The discovery is reported in the July 29 issue of the Proceedings of the National Academy of Sciences.The first farmerThe first farmers were found by Debra Brock, then a graduate student in the laboratory run by David Queller and Joan Strassmann at Rice University in Houston, Texas. (All three scientists have since moved to Washington University in St. Louis, where Queller and Strassmann are professors of biology and Brock is a research scientist.)Brock, who had worked for years with the standard axenic (pure, or uncontaminated) lab clone, noticed something strange about the D. …Read more
July 15, 2013 — In children with fever but no other symptoms of illness, it is difficult to know whether a child has a viral infection that will resolve on its own or a potentially serious bacterial infection that requires antibiotics.Now, researchers at Washington University School of Medicine in St. Louis report that they can distinguish between viral and bacterial infections in children with fever by profiling the activity of genes in a blood sample. In a small study, analyzing genes in white blood cells was more than 90 percent accurate, far better than the standard diagnostic test, which is only correct about 70 percent of the time.The research is published July 15 in the Proceedings of the National Academy of Sciences Online Early Edition.While more work is needed, the study’s results support the notion that analyzing the activity of the body’s genes in response to childhood infections could help to identify the cause of illness and ensure that children get the right treatment.”It’s a common problem that children develop a fever without any apparent cause,” says senior author Gregory Storch, MD, the Ruth L. Siteman Professor of Pediatrics and chief of the Division of Pediatric Infectious Diseases at Washington University School of Medicine and St. Louis Children’s Hospital. “Some of these kids have serious bacterial infections that can be life threatening, but the largest number have viral infections. The trouble is, from a practical standpoint, it’s hard to know which is which.”As a precaution, many children who have a fever without an apparent cause are treated with antibiotics even though the drugs don’t work against viruses and overprescribing them contributes to antibiotic resistance.The new study involved 30 children ages two months to 3 years who had fevers above 100.4° F but no obvious signs of illness, like a cough or diarrhea. Twenty-two of the children were known to have viral infections based on previous extensive genomic testing that is not yet practical to use in a clinic setting, and eight others children had bacterial infections.But Storch and his colleagues at the university’s Genome Institute and the Genome Technology Access Center wanted to know whether a test called a gene expression microarray could identify patterns of gene activity in white blood cells that could discriminate children with viral infections from those with bacterial infections. White blood cells are the immune system’s first line of defense against foreign invaders, and the scientists theorized that they would respond differently to viruses than to bacteria.The researchers also had access to results of a standard diagnostic test performed when the children initially were evaluated with fevers at St. Louis Children’s Hospital. …Read more
June 18, 2013 — Consumers are more likely to pursue goals when they are ambitious yet flexible, according to a new study in the Journal of Consumer Research.”Whether a goal is a high-low range goal (lose 2 to 4 pounds this week) or a single number goal (lose 3 pounds this week) has a systematic effect on goal reengagement. High-low range goals influence consumer goal reengagement through feelings of accomplishment, which itself is driven by the attainability and challenge of the goal,” write authors Maura L. Scott (Florida State University) and Stephen M. Nowlis (Washington University in St. Louis).Consumers often have a choice about the types of goals they want to set for themselves, and they may want to repeat various goals over time. For example, consumers often reengage goals such as losing weight, saving money, or improving their exercise or sports performance.In one study, consumers in a weight loss program set either high-low range goals or single number goals. At the end of the program, consumers with high-low range goals reenrolled in the program at higher rates even though there was no difference in actual average weight loss across the two groups. In other studies, consumers exhibited similar behaviors with other goals such as resisting tempting foods, solving puzzles, or playing a grocery shopping game.A high-low range goal can offer “the best of both worlds” compared to a single number goal due to its flexibility: the high end of the goal (lose 4 pounds) increases the challenge of the goal, while the low end (lose 2 pounds) increases its attainability. On the other hand, a single number goal (lose 3 pounds) may be perceived as a compromise and therefore both less challenging and less attainable.”Consumers are more likely to pursue a goal when they set a high-low range goal instead of a single number goal. Consumers experience a greater sense of accomplishment when a goal is both attainable and challenging, and this makes them want to continue to pursue or reengage their goal,” the authors conclude.Read more
June 5, 2013 — The World Health Organization lists shift work as a potential carcinogen, says Erik Herzog, PhD, Professor of Biology in Arts & Sciences at Washington University in St. Louis. And that’s just one example among many of the troubles we cause ourselves when we override the biological clocks in our brains and pay attention instead to the mechanical clocks on our wrists.In the June 5 issue of Neuron, Herzog and his colleagues report the discovery of a crucial part of the biological clock: the wiring that sets its accuracy to within a few minutes out of the 1440 minutes per day. This wiring uses the neurotransmitter, GABA, to connect the individual cells of the biological clock in a fast network that changes strength with time of day.Daily rhythms of sleep and metabolism are driven by a biological clock in the suprachiasmatic nucleus (SCN), a structure in the brain made up of 20,000 neurons, all of which can keep daily (circadian) time individually.If the SCN is to be a robust, but sensitive, timing system, the neurons must synchronize precisely with one another and adjust their rhythms to those of the environment.Herzog’s lab has discovered a push-pull system in the SCN that does both. In 2005 they reported that the neurons in the clock network communicate by means of a neuropeptide (VIP) that pushes them to synchronize with one another.And, as they now report in Neuron, these neurons also communicate with GABA that pulls on them weakly, so they are not too tightly coupled.Together these two networks (VIP and GABA) ensure the clock runs as coordinated, precise timepiece but one that can still adjust its timing to synchronize with the environment.”We think the neurotransmitter network is there to introduce enough jitter into the system to allow the neurons to resynchronize when environmental cues change, as they do with the seasons,” Herzog says.But, he says, since this biological ‘reset button’ evolved long before mechanical clocks, artificial lights, and high-speed travel, it doesn’t introduce enough jitter to allow us to adjust quickly to the extreme time shifts of modern life, such as flying “backward” (east) through several time zones.Understanding the push-pull system in the SCN has enormous implications for public health, bearing, as it does, on daylight saving times, shift work, school starting times, medical intern schedules, truck driver hours, and many other issues where the clock in the brain is pitted against the clock in the hand.Synchronizing the cellular clocksThe “clock” inside each SCN neuron depends on the cyclic expression of a family of genes such as the Period (PER) genes. The expression of these genes and the neuron’s firing rate typically peak at mid-day and fall at night. The gene activity is like the cogs in a clock, and the electrical activity like the hands on the clock.Each neuron in the SCN keeps time, but because they’re different cells, they have slightly different rhythms. Some run a little bit fast and others a bit slow. If the SCN as a whole is to function as a clock, its neurons need to synchronize with one another.The goal of the recent work in the Herzog lab has been to figure out how the clock cells are connected to each other. “It wasn’t clear, for example, if each neuron communicated with just a few of its neighbors or with all of them,” Herzog says.Mark Freeman, a graduate student in the lab, developed a method for recording the firing rate of about 100 neurons simultanously on a multi-electrode array. …Read more
May 29, 2013 — Researchers at Washington University School of Medicine in St. Louis have found that a popular artificial sweetener can modify how the body handles sugar.
In a small study, the researchers analyzed the sweetener sucralose (Splenda®) in 17 severely obese people who do not have diabetes and don’t use artificial sweeteners regularly.
“Our results indicate that this artificial sweetener is not inert — it does have an effect,” said first author M. Yanina Pepino, PhD, research assistant professor of medicine. “And we need to do more studies to determine whether this observation means long-term use could be harmful.”
The study is available online in the journal Diabetes Care.
Pepino’s team studied people with an average body mass index (BMI) of just over 42; a person is considered obese when BMI reaches 30. The researchers gave subjects either water or sucralose to drink before they consumed a glucose challenge test. The glucose dosage is very similar to what a person might receive as part of a glucose-tolerance test. The researchers wanted to learn whether the combination of sucralose and glucose would affect insulin and blood sugar levels.
“We wanted to study this population because these sweeteners frequently are recommended to them as a way to make their diets healthier by limiting calorie intake,” Pepino said.
Every participant was tested twice. Those who drank water followed by glucose in one visit drank sucralose followed by glucose in the next. In this way, each subject served as his or her own control group.
“When study participants drank sucralose, their blood sugar peaked at a higher level than when they drank only water before consuming glucose,” Pepino explained. “Insulin levels also rose about 20 percent higher. So the artificial sweetener was related to an enhanced blood insulin and glucose response.”
The elevated insulin response could be a good thing, she pointed out, because it shows the person is able to make enough insulin to deal with spiking glucose levels. But it also might be bad because when people routinely secrete more insulin, they can become resistant to its effects, a path that leads to type 2 diabetes.
It has been thought that artificial sweeteners, such as sucralose, don’t have an effect on metabolism. They are used in such small quantities that they don’t increase calorie intake. Rather, the sweeteners react with receptors on the tongue to give people the sensation of tasting something sweet without the calories associated with natural sweeteners, such as table sugar.
But recent findings in animal studies suggest that some sweeteners may be doing more than just making foods and drinks taste sweeter. One finding indicates that the gastrointestinal tract and the pancreas can detect sweet foods and drinks with receptors that are virtually identical to those in the mouth. That causes an increased release of hormones, such as insulin. Some animal studies also have found that when receptors in the gut are activated by artificial sweeteners, the absorption of glucose also increases.
Pepino, who is part of Washington University’s Center for Human Nutrition, said those studies could help explain how sweeteners may affect metabolism, even at very low doses. But most human studies involving artificial sweeteners haven’t found comparable changes.
“Most of the studies of artificial sweeteners have been conducted in healthy, lean individuals,” Pepino said. “In many of these studies, the artificial sweetener is given by itself. But in real life, people rarely consume a sweetener by itself. They use it in their coffee or on breakfast cereal or when they want to sweeten some other food they are eating or drinking.”
Just how sucralose influences glucose and insulin levels in people who are obese is still somewhat of a mystery.
“Although we found that sucralose affects the glucose and insulin response to glucose ingestion, we don’t know the mechanism responsible,” said Pepino. “We have shown that sucralose is having an effect. In obese people without diabetes, we have shown sucralose is more than just something sweet that you put into your mouth with no other consequences.”
She said further studies are needed to learn more about the mechanism through which sucralose may influence glucose and insulin levels, as well as whether those changes are harmful. A 20 percent increase in insulin may or may not be clinically significant, she added.
“What these all mean for daily life scenarios is still unknown, but our findings are stressing the need for more studies,” she said. “Whether these acute effects of sucralose will influence how our bodies handle sugar in the long term is something we need to know.”
Funding for this research comes from a National Center for Advancing Translational Sciences (NCATS) Clinical and Translational Sciences Award and subaward and from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH). Tate & Lyle provided the sucralose. NIH grant numbers: UL1 R000448, KL2 TR000450, DK0088126, DK37948 and DK56341.Read more