Leaf-mining insects destroyed with the dinosaurs, others quickly appeared

After the asteroid impact at the end of the Cretaceous period that triggered the dinosaurs’ extinction and ushered in the Paleocene, leaf-mining insects in the western United States completely disappeared. Only a million years later, at Mexican Hat, in southeastern Montana, fossil leaves show diverse leaf-mining traces from new insects that were not present during the Cretaceous, according to paleontologists.”Our results indicate both that leaf-mining diversity at Mexican Hat is even higher than previously recognized, and equally importantly, that none of the Mexican Hat mines can be linked back to the local Cretaceous mining fauna,” said Michael Donovan, graduate student in geosciences, Penn State.Insects that eat leaves produce very specific types of damage. One type is from leaf miners — insect larvae that live in the leaves and tunnel for food, leaving distinctive feeding paths and patterns of droppings.Donovan, Peter Wilf, professor of geosciences, Penn State, and colleagues looked at 1,073 leaf fossils from Mexican Hat for mines. They compared these with more than 9,000 leaves from the end of the Cretaceous, 65 million years ago, from the Hell Creek Formation in southwestern North Dakota, and with more than 9,000 Paleocene leaves from the Fort Union Formation in North Dakota, Montana and Wyoming. The researchers present their results in today’s (July 24) issue of PLOS ONE.”We decided to focus on leaf miners because they are typically host specific, feeding on only a few plant species each,” said Donovan. “Each miner also leaves an identifiable mining pattern.”The researchers found nine different mine-damage types at Mexican Hat attributable to the larvae of moths, wasps and flies, and six of these damage types were unique to the site.The researchers were unsure whether the high diversity of leaf miners at Mexican Hat compared to other early Paleocene sites, where there is little or no leaf mining, was caused by insects that survived the extinction event in refugia — areas where organisms persist during adverse conditions — or were due to range expansions of insects from somewhere else during the early Paleocene.However, with further study, the researchers found no evidence of the survival of any leaf miners over the Cretaceous-Paleocene boundary, suggesting an even more total collapse of terrestrial food webs than has been recognized previously.”These results show that the high insect damage diversity at Mexican Hat represents an influx of novel insect herbivores during the early Paleocene and not a refugium for Cretaceous leaf miners,” said Wilf. “The new herbivores included a startling diversity for any time period, and especially for the classic post-extinction disaster interval.”Insect extinction across the Cretaceous-Paleocene boundary may have been directly caused by catastrophic conditions after the asteroid impact and by the disappearance of host plant species. While insect herbivores constantly need leaves to survive, plants can remain dormant as seeds in the ground until more auspicious circumstances occur.The low-diversity flora at Mexican Hat is typical for the area in the early Paleocene, so what caused the high insect damage diversity?Insect outbreaks are associated with a rapid population increase of a single insect species, so the high diversity of mining damage seen in the Mexican Hat fossils makes the possibility of an outbreak improbable.The researchers hypothesized that the leaf miners that are seen in the Mexican Hat fossils appeared in that area because of a transient warming event, a number of which occurred during the early Paleocene.”Previous studies have shown a correlation between temperature and insect damage diversity in the fossil record, possibly caused by evolutionary radiations or range shifts in response to a warmer climate,” said Donovan. “Current evidence suggests that insect herbivore extinction decreased with increasing distance from the asteroid impact site in Mexico, so pools of surviving insects would have existed elsewhere that could have provided a source for the insect influx that we observed at Mexican Hat.”Story Source:The above story is based on materials provided by Penn State. The original article was written by A’ndrea Eluse Messer. …

Read more

Misleading mineral may have resulted in overestimate of water in moon

The amount of water present in the moon may have been overestimated by scientists studying the mineral apatite, says a team of researchers led by Jeremy Boyce of the UCLA Department of Earth, Planetary and Space Sciences.Boyce and his colleagues created a computer model to accurately predict how apatite would have crystallized from cooling bodies of lunar magma early in the moon’s history. Their simulations revealed that the unusually hydrogen-rich apatite crystals observed in many lunar rock samples may not have formed within a water-rich environment, as was originally expected.This discovery has overturned the long-held assumption that the hydrogen in apatite is a good indicator of overall lunar water content.”The mineral apatite is the most widely used method for estimating the amount of water in lunar rocks, but it cannot be trusted,” said Boyce, who is an adjunct assistant professor in the UCLA College of Letters and Science. “Our new results show that there is not as much water in lunar magma as apatite would have us believe.”The research was published online March 20 in the journal Science on and will be published in a future print edition.For decades, scientists believed the moon was almost entirely devoid of water. However, the discovery of hydrogen-rich apatite within lunar rocks in 2010 seemed to hint at a more watery past. Scientists originally assumed that information obtained from a small sample of apatite could predict the original water content of a large body of magma, or even the entire moon, but Boyce’s study indicates that apatite may, in fact, be deceptive.Boyce believes the high water content within lunar apatite results from a quirk in the crystallization process rather than a water-rich lunar environment. When water is present as molten rock cools, apatite can form by incorporating hydrogen atoms into its crystal structure. However, hydrogen will be included in the newly crystallizing mineral only if apatite’s preferred building blocks, fluorine and chlorine, have been mostly exhausted.”Early-forming apatite is so fluorine-rich that it vacuums all the fluorine out of the magma, followed by chlorine,” Boyce said. “Apatite that forms later doesn’t see any fluorine or chlorine and becomes hydrogen-rich because it has no choice.”Therefore, when fluorine and chlorine become depleted, a cooling body of magma will shift from forming hydrogen-poor apatite to forming hydrogen-rich apatite, with the latter not accurately reflecting the original water content in the magma.Understanding the story of lunar apatite has implications beyond determining how much water is locked inside lunar rocks and soil. According to the predominant theory of how the moon originally formed, hydrogen and other volatile elements should not be present at all in lunar rocks.Many scientists theorize that the moon formed when a giant impact tore free a large chunk of Earth more than 4 billion years ago. If this “giant impact” model is correct, the moon would have been completely molten, and lighter elements such as hydrogen should have bubbled to the surface and escaped into space. …

Read more

Nearly complete ‘chicken from hell,’ from mysterious dinosaur group

A team of researchers has announced the discovery of a bizarre, bird-like dinosaur, named Anzu wyliei, that provides paleontologists with their first good look at a dinosaur group that has been shrouded in mystery for almost a century. Anzu was described from three specimens that collectively preserve almost the entire skeleton, giving scientists a remarkable opportunity to study the anatomy and evolutionary relationships of Caenagnathidae (pronounced SEE-nuh-NAY-thih-DAY) — the long-mysterious group of theropod dinosaurs to which Anzu belongs.The three described fossil skeletons of Anzu were unearthed in North and South Dakota, from roughly 66 million-year-old rocks of the Hell Creek Formation, a rock unit celebrated for its abundant fossils of famous dinosaurs such as Tyrannosaurus rex and Triceratops. The scientific paper describing the discovery appears today in the freely-accessible journal PLOS ONE.The team of scientists who studied Anzu was led by Dr. Matthew Lamanna of Carnegie Museum of Natural History in Pittsburgh. Dr. Lamanna’s collaborators include Dr. Hans-Dieter Sues and Dr. Tyler Lyson of the Smithsonian Institution’s National Museum of Natural History in Washington, DC, and Dr. Emma Schachner of the University of Utah in Salt Lake City. According to Dr. …

Read more

Serpentine ecosystems shed light on nature of plant adaptation, speciation

Plants that live in unusual soils, such as those that are extremely low in essential nutrients, provide insight into the mechanisms of adaptation, natural selection, and endemism. A seminal paper by Arthur Kruckeberg from 1951 on serpentine plant endemism has served as a solid bedrock foundation for future research on the link between natural selection and speciation. A recent article in the American Journal of Botany focuses on how this paper has influenced subsequent research on local adaptation, evolutionary pathways, and the relationship between climate, soils, and endemism.In the latest in a series of AJB Centennial Review papers, AJB Anacker (University of California, Davis) examines the impact that Kruckeberg’s 1951 AJB paper has had on our subsequent understanding of plant evolution and ecology.Kruckeberg’s classic paper reported on reciprocal transplant experiments, in which he made several generalizations about plant competition, local adaptation, and speciation. Kruckeberg showed that the strong selective pressures of serpentine soils — characterized by low amounts of essential nutrients and water, and high in heavy metals — can lead to the formation of soil ecotypes (genetically distinct plant varieties), representing a possible first step in the evolution of serpentine endemism (e.g., plants that are only found on serpentine type soils). These important initial findings spurred subsequent research on determining plant traits (from molecular to organismal) that underlie serpentine adaptation.Anacker draws attention to a second significant contribution of Kruckeberg’s paper — researching the historic origins of endemic species, such as those found in serpentine soils. Anacker explains that endemic species are thought to originate in two ways: neoendemics are species that have formed relatively recently via nearby progenitor taxa, and paleoendemics are species that formed following habitat-specific population extirpation. Kruckeberg viewed serpentine ecotypes as representing the first step along the path of paleoendemism. While this stimulated much research in this area, Anacker points out that several serpentine endemics appear to have arisen from nearby progenitor taxa, and thus the neoendemic pathway is also likely important.Interestingly, Kruckeberg’s experiments also showed that many serpentine ecotypes actually performed better on the non-serpentine soils than on serpentine soils, which begs the question of why serpentine-adapted plants are not also found on non-serpentine soils. Anacker points out that Kruckeberg was one of the first to indicate that competition may play a key role in serpentine specialization. He also highlights recent research indicating that serpentine species are typically slow-growing stress tolerators rather than fast-growing competitive dominants, and their adaptations for being more drought-tolerant puts them at a disadvantage in soils where water and nutrients are not limiting.While serpentine ecosystems are special and unique environments, Kruckeberg and subsequent researchers have shown how important these systems are for shedding light on broader aspects of plant ecology and evolution.The 1951 paper can be accessed online at: http://www.jstor.org/discover/10.2307/2438248?uid=3739448&uid=2&uid=3737720&uid=4&sid=21103728973903Story Source:The above story is based on materials provided by American Journal of Botany. …

Read more

Competition breeds new fish species, study finds

Competition may play an important role during the evolution of new species, but empirical evidence for this is scarce, despite being implicit in Charles Darwin’s work and support from theoretical studies.Dr Martin Genner from Bristol’s School of Biological Sciences and colleagues used population genetics and experimental evidence to demonstrate a role for competition that leads to the differentiation of new species within the highly diverse cichlid fishes of Lake Tanganyika in East Africa.They found that the cichlid fish Telmatochromis temporalis shows two genetically distinct ecomorphs (local varieties of a species whose appearance is determined by its ecological environment), that strongly differ in body size and the habitat in which they live.Dr Genner said: “We found large-sized individuals living along the rocky shoreline of Lake Tanganyika and, in the vicinity of these shores, we found small-sized individuals, roughly half the size of the large ones, that live and breed in accumulations of empty snail shells found on sand.”According to the study, the bigger fish outcompete the smaller ones, driving them away from the preferred rocky habitats and into the neighbouring sand, where the smaller fish find shelter for themselves and their eggs in empty snail shells.”In effect, big and small fish use different habitats; and because of this habitat segregation, fish usually mate with individuals of similar size. There is virtually no genetic exchange between the large- and small-bodied ectomorphs,” Dr Genner commented.Speciation occurs when genetic differences between groups of individuals accumulate over time. In the case of Telmatochromis there are no obvious obstacles to the movement and interaction of individuals. But, the non-random mating between large- and small-bodied fish sets the stage for the evolutionary play.Dr Genner said: “The relevance of our work is that it provides experimental evidence that competition for space drives differential mating in cichlid fish and, in time, leads to the formation of new species. Nature has its ways — from body size differences to the formation of new species. And clearly, size does matters for Telmatochromis and for fish diversity.”Story Source:The above story is based on materials provided by University of Bristol. Note: Materials may be edited for content and length.

Read more

Sound-sensing cells regenerated in ears of mice with hearing damage

One of the major causes of hearing loss in mammals is damage to the sound-sensing hair cells in the inner ear. For years, scientists have thought that these cells are not replaced once they’re lost, but new research appearing online February 20 in the journal Stem Cell Reports reveals that supporting cells in the ear can turn into hair cells in newborn mice. If the findings can be applied to older animals, they may lead to ways to help stimulate cell replacement in adults and to the design of new treatment strategies for people suffering from deafness due to hair cell loss.Whereas previous research indicated that hair cells are not replaced, this latest study found that replacement does indeed occur, but at very low levels. “The finding that newborn hair cells regenerate spontaneously is novel,” says senior author Dr. Albert Edge of Harvard Medical School and Massachusetts Eye and Ear Infirmary.The team’s previous research revealed that inhibition of the Notch signaling pathway increases hair cell differentiation and can help restore hearing to mice with noise-induced deafness. In their latest work, the investigators found that blocking the Notch pathway increases the formation of new hair cells not from remaining hair cells but from certain nearby supporting cells that express a protein called Lgr5.”By using an inhibitor of Notch signaling, we could push even more cells to differentiate into hair cells,” says Dr. Edge. “It was surprising that the Lgr5-expressing cells were the only supporting cells that differentiated under these conditions.”Combining this new knowledge about Lgr5-expressing cells with the previous finding that Notch inhibition can regenerate hair cells will allow the scientists to design new hair cell regeneration strategies to treat hearing loss and deafness.Story Source:The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.

Read more

Excess weight linked to brain changes that may relate to memory, emotions, and appetite

Being overweight appears related to reduced levels of a molecule that reflects brain cell health in the hippocampus, a part of the brain involved in memory, learning, and emotions, and likely also involved in appetite control, according to a study performed by researchers at SUNY Downstate Medical Center and other institutions. The results of the study were published in Neuroimage: Clinical.Jeremy D. Coplan, MD, professor of psychiatry at SUNY Downstate, led a multicenter team that visualized the molecule, N-acetyl-aspartate (NAA), using magnetic resonance spectroscopy, a non-invasive magnetic resonance imaging (MRI) application. NAA is associated with brain cell health. Overweight study participants exhibited lower levels of NAA in the hippocampus than normal weight subjects. The effect was independent of age, sex, and psychiatric diagnoses.The importance of the hippocampus — a seahorse-shaped organ deep within the brain — to the formation and preservation of memory and to emotional control is well known, Dr. Coplan notes, but its role in appetite control is less established.”The relevance of the finding is that being overweight is associated with specific changes in a part of the brain that is crucial to memory formation and emotions, and probably to appetite,” said Dr. Coplan. The study is believed to be the first human research documenting the association of NAA with body weight.”Whether low NAA is a consequence of being overweight, causes being overweight, or a combination of both remains to be determined,” Dr. Coplan added. …

Read more

Strange marine mammals of ancient North Pacific revealed

The pre-Ice Age marine mammal community of the North Pacific formed a strangely eclectic scene, research by a Geology PhD student at New Zealand’s University of Otago reveals.Studying hundreds of fossil bones and teeth he excavated from the San Francisco Bay Area’s Purisima Formation, Robert Boessenecker has put together a record of 21 marine mammal species including dwarf baleen whales, odd double-tusked walruses, porpoises with severe underbites and a dolphin closely related to the now-extinct Chinese river dolphin.Among his finds, which were fossilized 5 to 2.5 million years ago, is a new species of fossil whale, dubbed Balaenoptera bertae, a close relative of minke, fin, and blue whales.Mr Boessenecker named the whale in honour of San Diego State University’s Professor Annalisa Berta, who has made numerous contributions to the study of fossil marine mammals and mentored many students.Although an extinct species, it belongs within the same genus as minke and fin whales, indicating that the Balaenoptera lineage has lasted for 3-4 million years. Balaenoptera bertae would have been approximately 5-6 meters in length, slightly smaller than modern minke whales, Mr Boessenecker says.His findings appear in the most recent edition of the international journal Geodiversitas.The publication represents eight years of research by Mr Boessenecker, who was 18 in 2004 when he was tipped off by a local surfer about bones near Half Moon Bay. When he discovered the fossil site, he was astonished by the numerous bone-beds and hundreds of bones sticking out of the cliffs.He excavated the incomplete skull of Balaenoptera bertae during early field research there in 2005 and it was encased in a hard concretion that took five years to remove.”The mix of marine mammals I ended up uncovering was almost completely different to that found in the North Pacific today, and to anywhere else at that time,” he says.Primitive porpoises and baleen whales were living side-by-side with comparatively modern marine mammals such as the Northern fur seal and right whales. And species far geographically and climatically removed from their modern relatives also featured, such as beluga-like whales and tusked walruses, which today live in the Arctic, he says.”At the same time as this eclectic mix of ancient and modern-type marine mammals was living together, the marine mammal fauna in the North Atlantic and Southern Ocean were already in the forms we find today.”Mr Boessenecker says this strange fauna existed up until as recently as one or two million years ago. Its weirdness was likely maintained by warm equatorial waters and barriers to migration by other marine mammals posed by the newly formed Isthmus of Panama, and the still-closed Bering Strait.”Once the Bering Strait opened and the equatorial Pacific cooled during the Ice Age, modernised marine mammals were able to migrate from other ocean basins into the North Pacific, leading to the mix we see today,” he says.Story Source:The above story is based on materials provided by University of Otago. Note: Materials may be edited for content and length.

Read more

Finding blood clots before they wreak havoc

Oct. 16, 2013 — Life-threatening blood clots can form in anyone who sits on a plane for a long time, is confined to bed while recovering from surgery, or takes certain medications.There is no fast and easy way to diagnose these clots, which often remain undetected until they break free and cause a stroke or heart attack. However, new technology from MIT may soon change that: A team of engineers has developed a way to detect blood clots using a simple urine test.The noninvasive diagnostic, described in a recent issue of the journal ACS Nano, relies on nanoparticles that detect the presence of thrombin, a key blood-clotting factor.Such a system could be used to monitor patients who are at high risk for blood clots, says Sangeeta Bhatia, senior author of the paper and the John and Dorothy Wilson Professor of Biochemistry.”Some patients are at more risk for clotting, but existing blood tests are not consistently able to detect the formation of new clots,” says Bhatia, who is also a senior associate member of the Broad Institute and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES).Lead authors of the paper are Kevin Lin, a graduate student in chemical engineering, and Gabriel Kwong, a postdoc in IMES. Other authors are Andrew Warren, a graduate student in Health Sciences and Technology (HST), and former HST postdoc David Wood.Sensing thrombinBlood clotting is produced by a complex cascade of protein interactions, culminating in the formation of fibrin, a fibrous protein that seals wounds. The last step of this process — the conversion of fibrinogen to fibrin — is controlled by an enzyme called thrombin.Current tests for blood clotting are very indirect, Bhatia says. One, known as the D-dimer test, looks for the presence of fibrin byproducts, which indicates that a clot is being broken down, but will not detect its initial formation.Bhatia and her colleagues developed their new test based on a technology they first reported last year for early detection of colorectal cancer. “We realized the same exact technology would work for blood clots,” she says. “So we took the test we had developed before, which is an injectable nanoparticle, and made it a thrombin sensor.”The system consists of iron oxide nanoparticles, which the Food and Drug Administration has approved for human use, coated with peptides (short proteins) that are specialized to interact with thrombin. After being injected into mice, the nanoparticles travel throughout the body. When the particles encounter thrombin, the thrombin cleaves the peptides at a specific location, releasing fragments that are then excreted in the animals’ urine.Once the urine is collected, the protein fragments can be identified by treating the sample with antibodies specific to peptide tags included in the fragments. …

Read more

Genes predispose some people to focus on the negative

Oct. 10, 2013 — A new study by a University of British Columbia researcher finds that some people are genetically predisposed to see the world darkly.The study, published in Psychological Science, finds that a previously known gene variant can cause individuals to perceive emotional events — especially negative ones — more vividly than others.”This is the first study to find that this genetic variation can significantly affect how people see and experience the world,” says Prof. Rebecca Todd of UBC’s Dept. of Psychology. “The findings suggest people experience emotional aspects of the world partly through gene-coloured glasses — and that biological variations at the genetic level can play a significant role in individual differences in perception.”The gene in question is the ADRA2b deletion variant, which influences the hormone and neurotransmitter norepinephrine. Previously found to play a role in the formation of emotional memories, the new study shows that the ADRA2b deletion variant also plays a role in real-time perception.The study’s 200 participants were shown positive, negative and neutral words in a rapid succession. Participants with the ADRA2b gene variant were more likely to perceive negative words than others, while both groups perceived positive words better than neutral words to an equal degree.”These individuals may be more likely to pick out angry faces in a crowd of people,” says Todd. “Outdoors, they might notice potential hazards — places you could slip, loose rocks that might fall — instead of seeing the natural beauty.”The findings shed new light on ways in which genetics — combined with other factors such as education, culture, and moods — can affect individual differences in emotional perception and human subjectivity, the researchers say.BackgroundFurther research is planned to explore this phenomenon across ethnic groups. While more than half of Caucasians are believed to have the ADRA2b gene variant, statistics suggest it is significantly less prevalent in other ethnicities. For example, a recent study found that only 10 per cent of Rwandans had the ADRA2b gene variant.The study was co-led by UBC Prof. …

Read more

Novel way discovered to ‘switch on’ tumor suppressors that have been silenced

Oct. 9, 2013 — A team of scientists from the Cancer Science Institute of Singapore (CSI Singapore) at the National University of Singapore (NUS) and their collaborators from the Harvard Stem Cell Institute have found that a novel noncoding ribonucleic acid (RNA) offers the potential for “switching on” of tumour suppressors that have been shut off.The research group, led by Professor Daniel Tenen, Director of CSI Singapore, demonstrated for first time that RNA interacts with an enzyme essential for DNA methylation, known as DNA methyl transferase 1 (DNMT1), offering strategies for the treatment of diseases such as cancer.In this study, the researchers focused on a new class of RNAs, which is critical in regulating DNA methylation. This is a process in which certain building blocks of DNA, the genetic code, are chemically modified without resulting in a change in the code itself. DNA methylation is associated with silencing of gene expression and found in many diseases. For example, in cancer, genes called tumour suppressors, which inhibit tumour formation, are often silenced or shut off in the cancer cells, and this is associated with DNA methylation.This novel study was first published online in the research journal Nature on 9 October 2013.How the novel noncoding RNA inhibits DNA methylationThe study focused on this novel noncoding RNA in a specific tumour suppressor, known as CEBPA. The silencing of CEPBA is associated with Acute Myeloid Leukemia, lung cancer and other types of cancer. The scientists demonstrated that the noncoding RNA binds to the enzyme DNMT1 and prevents DNA methylation of the CEBPA gene. This principle, which is likely to extend to thousands of other genes, can potentially be used to “switch on” tumour suppressors that have been shut off.Prof Tenen said, “We started out by studying the noncoding RNA to satisfy our scientific curiosity. In the process, we discovered the novel finding that RNA inhibits methylation and experimentally, we can introduce RNAs to ‘switch on’ tumour suppressors which have been shut off. Our results suggest strategies for gene-selective demethylation of therapeutic targets in human diseases such as cancer.”Further ResearchIn the next phase of their research, the scientists will look into developing tools for targeted activation of other tumour suppressors, besides CEBPA, and investigate the role of RNA in regulating other epigenetic marks.

Read more

Scientists pinpoint proteins vital to long-term memory

Sep. 12, 2013 — Scientists from the Florida campus of The Scripps Research Institute (TSRI) have found a group of proteins essential to the formation of long-term memories.The study, published online ahead of print on September 12, 2013 by the journal Cell Reports, focuses on a family of proteins called Wnts. These proteins send signals from the outside to the inside of a cell, inducing a cellular response crucial for many aspects of embryonic development, including stem cell differentiation, as well as for normal functioning of the adult brain.”By removing the function of three proteins in the Wnt signaling pathway, we produced a deficit in long-term but not short-term memory,” said Ron Davis, chair of the TSRI Department of Neuroscience. “The pathway is clearly part of the conversion of short-term memory to the long-term stable form, which occurs through changes in gene expression.”The findings stem from experiments probing the role of Wnt signaling components in olfactory memory formation in Drosophila, the common fruit fly — a widely used doppelgänger for human memory studies. In the new study, the scientists inactivated the expression of several Wnt signaling proteins in the mushroom bodies of adult flies — part of the fly brain that plays a role in learning and memory.The resulting memory disruption, Davis said, suggests that Wnt signaling participates actively in the formation of long-term memory, rather than having some general, non-specific effect on behavior.”What is interesting is that the molecular mechanisms of adult memory use the same processes that guide the early development of the organism, except that they are repurposed for memory formation,” he said. “One difference, however, is that during early development the signals are intrinsic, while in adults they require an outside stimulus to create a memory.”The first author of the study, “Wnt signaling is required for long-term memory formation,” is Ying Tan of the Baylor College of Medicine. Other authors include Germain U. Busto of TSRI and Curtis Wilson of Baylor College of Medicine.The study was supported by the National Institutes of Health (NS19904).

Read more

Iron in the sun: A greenhouse gas for X-ray radiation

Sep. 6, 2013 — Scientists from the Heidelberg Max Planck Institute for Nuclear Physics (MPIK) in cooperation with DESY (Hamburg) at the synchrotron PETRA III have investigated for the first time X-ray absorption of highly charged iron ions. A transportable ion trap developed at MPIK was used for generation and storage of the ions. The high-precision measurements provide important new insight into the role of highly charged ions in astrophysical plasmas, e. g. for radiation transport inside stars.Highly charged ions — that is, atoms which have been stripped off most of their electrons — play an important role in astrophysics. Within the large accumulations of visible (luminous) matter in the universe, the highly charged state is the natural one. This is the case in stellar atmospheres as well as in the interior of stars, where temperatures of several million degrees Celsius rule. Highly charged ions also abound around exotic objects such as neutron stars or black holes. Before matter plunges into their cores, it delivers gravitational energy, heating up and emitting extremely intense X-rays, which can be observed.X-rays also determine the energy transport inside the Sun. …

Read more

Primate calls, like human speech, can help infants form categories

Sep. 2, 2013 — Human infants’ responses to the vocalizations of non-human primates shed light on the developmental origin of a crucial link between human language and core cognitive capacities, a new study reports.Previous studies have shown that even in infants too young to speak, listening to human speech supports core cognitive processes, including the formation of object categories.Alissa Ferry, lead author and currently a postdoctoral fellow in the Language, Cognition and Development Lab at the Scuola Internationale Superiore di Studi Avanzati in Trieste, Italy, together with Northwestern University colleagues, documented that this link is initially broad enough to include the vocalizations of non-human primates.”We found that for 3- and 4-month-old infants, non-human primate vocalizations promoted object categorization, mirroring exactly the effects of human speech, but that by six months, non-human primate vocalizations no longer had this effect — the link to cognition had been tuned specifically to human language,” Ferry said.In humans, language is the primary conduit for conveying our thoughts. The new findings document that for young infants, listening to the vocalizations of humans and non-human primates supports the fundamental cognitive process of categorization. From this broad beginning, the infant mind identifies which signals are part of their language and begins to systematically link these signals to meaning.Furthermore, the researchers found that infants’ response to non-human primate vocalizations at three and four months was not just due to the sounds’ acoustic complexity, as infants who heard backward human speech segments failed to form object categories at any age.Susan Hespos, co-author and associate professor of psychology at Northwestern said, “For me, the most stunning aspect of these findings is that an unfamiliar sound like a lemur call confers precisely the same effect as human language for 3- and 4-month-old infants. More broadly, this finding implies that the origins of the link between language and categorization cannot be derived from learning alone.””These results reveal that the link between language and object categories, evident as early as three months, derives from a broader template that initially encompasses vocalizations of human and non-human primates and is rapidly tuned specifically to human vocalizations,” said Sandra Waxman, co-author and Louis W. Menk Professor of Psychology at Northwestern.Waxman said these new results open the door to new research questions.”Is this link sufficiently broad to include vocalizations beyond those of our closest genealogical cousins,” asks Waxman, “or is it restricted to primates, whose vocalizations may be perceptually just close enough to our own to serve as early candidates for the platform on which human language is launched?”

Read more

A fluffy disk around a baby star

Aug. 23, 2013 — An international team of astronomers that are members of the Strategic Exploration of Exoplanets and Disks with Subaru Telescope (SEEDS) Project has used Subaru Telescope’s High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) to observe a disk around the young star RY Tau (Tauri). The team’s analysis of the disk shows that a “fluffy” layer above it is responsible for the scattered light observed in the infrared image. Detailed comparisons with computer simulations of scattered light from the disk reveal that this layer appears to be a remnant of material from an earlier phase of stellar and disk development, when dust and gas were falling onto the disk.Since 2009, the five-year SEEDS Project (Note) has focused on direct imaging of exoplanets, i.e., planets orbiting stars outside of our Solar System, and disks around a targeted total of 500 stars. Planet formation, an exciting and active area for astronomical research, has long fascinated many scientists. Disks of dust and gas that rotate around young stars are of particular interest, because astronomers think that these are the sites where planets form–in these so-called “protoplanetary disks.” Since young stars and disks are born in molecular clouds, giant clouds of dust and gas, the role of dust becomes an important feature of understanding planet formation; it relates not only to the formation of rocky, Earth-like planets and the cores of giant Jupiter-like planets but also to that of moons, planetary rings, comets, and asteroids.As a part of the SEEDS Project, the current team of researchers used HiCIAO mounted on the Subaru Telescope to observe a possible planet-forming disk around the young star RY Tau. This star is about 460 light years away from Earth in the constellation Taurus and is around half a million years old. The disk has a radius of about 70 AU (10 billion kilometers), which is a few times larger than the orbit of Neptune in our own Solar System.Astronomers have developed powerful instruments to obtain images of protoplanetary disks, and Subaru Telescope’s HiCIAO is one of them. HiCIAO uses a mask to block out the light of the central star, which may be a million times brighter than its disk. They can then observe light from the star that has been reflected from the surface of the disk. …

Read more

Cells that line blood vessels created

Aug. 22, 2013 — In a scientific first, Harvard Stem Cell Institute scientists have successfully grown the cells that line the blood vessels — called vascular endothelial cells — from human induced pluripotent stem cells (iPSCs), revealing new details about how these cells function. Using a unique approach, the researchers induced the differentiation of specific cell types by generating mechanical forces on the surface of the iPSC-derived endothelium mimicking the flow of blood. For example, cells that felt a stronger “flow” became artery cells, while those that felt a weaker “flow” became vein cells.”It was especially exciting to us to discover that these cells are basically responding to biomechanical cues,” research leader Guillermo García-Cardena, PhD, an HSCI Affiliated Faculty member, said. “By exposing cells to ‘atheroprone flow,’ we can direct differentiation of these cells into cells that are present in areas of the circulatory system that we know are affected by diseases like atherosclerosis.” García-Cardena is now working on modeling the formation of arterial plaques using human iPSC-derived vascular endothelial cells and identifying potential drugs that might prevent plaque formation.García-Cardena’s team, which included Harvard School of Engineering and Applied Sciences graduate student William Adams, found that the iPS-derived human endothelial cells display three critical functions carried out by mature endothelium in the body: mounting inflammatory responses, keeping blood from leaking out of the blood vessel, and preventing blood clots.Based on this information, García-Cardena’s work, published this month in the journal Stem Cell Reports, has another exciting implication — it could potentially reduce, or even eliminate the need for heparin use during kidney dialysis and lung failure treatment — making both markedly safer.Traditionally, patients undergoing dialysis are treated with heparin, a powerful drug, which prevents the blood from clotting as it’s routed through the dialysis machine. While heparin is quite effective in preventing clotting, because it considerably thins the blood, it can also cause loss of blood, internal bleeding, and interfere with the healing process.”The iPSC-derived endothelial cells cells beautifully function as an anticoagulant surface,” said García-Cardena, an Associate Professor of Pathology at Harvard Medical School and Brigham and Women’s Hospital. “In the future, we may take a tissue sample from a patient, generate iPSCs, and then cover an extracorporeal device with the patient’s own endothelial cells — so the patient can go home with the device without the need for regular heparin shots.”

Read more

‘Zombie vortices’ may be key step in star formation

Aug. 20, 2013 — A new theory by fluid dynamics experts at the University of California, Berkeley, shows how “zombie vortices” help lead to the birth of a new star.Reporting Aug. 20 in the journal Physical Review Letters, a team led by computational physicist Philip Marcus shows how variations in gas density lead to instability, which then generates the whirlpool-like vortices needed for stars to form.Astronomers accept that in the first steps of a new star’s birth, dense clouds of gas collapse into clumps that, with the aid of angular momentum, spin into one or more Frisbee-like disks where a protostar starts to form. But for the protostar to grow bigger, the spinning disk needs to lose some of its angular momentum so that the gas can slow down and spiral inward onto the protostar. Once the protostar gains enough mass, it can kick off nuclear fusion.”After this last step, a star is born,” said Marcus, a professor in the Department of Mechanical Engineering.What has been hazy is exactly how the cloud disk sheds its angular momentum so mass can feed into the protostar.Destabilizing forcesThe leading theory in astronomy relies on magnetic fields as the destabilizing force that slows down the disks. One problem in the theory has been that gas needs to be ionized, or charged with a free electron, in order to interact with a magnetic field. However, there are regions in a protoplanetary disk that are too cold for ionization to occur.”Current models show that because the gas in the disk is too cool to interact with magnetic fields, the disk is very stable,” said Marcus. “Many regions are so stable that astronomers call them dead zones — so it has been unclear how disk matter destabilizes and collapses onto the star.”The researchers said current models also fail to account for changes in a protoplanetary disk’s gas density based upon its height.”This change in density creates the opening for violent instability,” said study co-author Pedram Hassanzadeh, who did this work as a UC Berkeley Ph.D. student in mechanical engineering. When they accounted for density change in their computer models, 3-D vortices emerged in the protoplanetary disk, and those vortices spawned more vortices, leading to the eventual disruption of the protoplanetary disk’s angular momentum.”Because the vortices arise from these dead zones, and because new generations of giant vortices march across these dead zones, we affectionately refer to them as ‘zombie vortices,'” said Marcus. …

Read more

Iron is at core of Alzheimer’s disease, study suggests

Aug. 20, 2013 — Alzheimer’s disease has proven to be a difficult enemy to defeat. After all, aging is the No. 1 risk factor for the disorder, and there’s no stopping that.Most researchers believe the disease is caused by one of two proteins, one called tau, the other beta-amyloid. As we age, most scientists say, these proteins either disrupt signaling between neurons or simply kill them.Now, a new UCLA study suggests a third possible cause: iron accumulation.Dr. George Bartzokis, a professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA and senior author of the study, and his colleagues looked at two areas of the brain in patients with Alzheimer’s. They compared the hippocampus, which is known to be damaged early in the disease, and the thalamus, an area that is generally not affected until the late stages. Using sophisticated brain-imaging techniques, they found that iron is increased in the hippocampus and is associated with tissue damage in that area. But increased iron was not found in the thalamus.The research appears in the August edition of the Journal of Alzheimer’s Disease.While most Alzheimer’s researchers focus on the buildup of tau or beta-amyloid that results in the signature plaques associated with the disease, Bartzokis has long argued that the breakdown begins much further “upstream.” The destruction of myelin, the fatty tissue that coats nerve fibers in the brain, he says, disrupts communication between neurons and promotes the buildup of the plaques. These amyloid plaques in turn destroy more and more myelin, disrupting brain signaling and leading to cell death and the classic clinical signs of Alzheimer’s.Myelin is produced by cells called oligodendrocytes. …

Read more

Novel Chinese herbal medicine JSK improves spinal cord injury outcomes in rats

Aug. 19, 2013 — A new study published in Restorative Neurology and Neuroscience demonstrates that Chinese herbal medicine Ji-Sui-Kang (JSK), given systemically for three weeks after injury in rats, improved locomotor function, reduced tissue damage, and preserved the structure of neural cells compared to control rats. The report also includes data showing that JSK may first act to reduce inflammation and cell apoptosis and death, and boost local oxygen supply while, later on, it appears to restore function and promote tissue regeneration.Although Chinese herbal medicines have traditionally been used for a variety of ailments, the rationale for their use relies more on anecdotal evidence than the results of modern-day controlled experiments.”A number of anecdotal reports from Chinese medicine practitioners indicate that treatment with a novel herbal formulation, JSK, for periods of one week or three months improved functional recovery,” explains co-lead investigator Shucui Jiang, MD, PhD, head of the Hamilton NeuroRestorative Group at McMaster University in Hamilton, Ontario, Canada. “Our present study provides an important and necessary foundation for further studies of JSK.”In this study rats began JSK treatment immediately after undergoing spinal cord injury. Within 7 days, hindlimb locomotor function was significantly better in JSK-treated rats compared to those receiving only saline. JSK-treated rats continued to have better motor function than controls throughout the 21-day test period and treated animals appeared to support their weight better and have more coordinated movements.When the investigators looked at histological samples of the spinal cord, they found that the architecture of the spinal cord was better preserved in JSK-treated animals and the size of the injured area was significantly smaller 7 days after injury. JSK-treated animals also showed more intact axons and myelin in the injured areas compared to controls. Other encouraging signs were less deposition of fibrinogen in the injured areas of JSK-treated animals, a decrease in pro-inflammatory COX-2 expression, and fewer cell deaths at the lesion site (as measured by caspase-3 staining).JSK also increased the expression of growth associated protein 43 (GAP43), a marker of neuronal development and axonal regeneration, and neuroglobulin, a protein found in cerebral neurons that is thought to help neurons survive and recover after trauma. “Our data suggest that JSK may enhance tissue recovery by reducing cell growth inhibitors and by promoting the proliferation of cells within the injured spinal cord,” says co-lead investigator Michel P. Rathbone, MD, CHB, PhD, Professor, Division of Neurology, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.Other findings suggest JSK might help protect against injury caused by damage to spinal cord blood vessels. …

Read more

Tumors form advance teams to ready lungs for spread of cancer

Aug. 16, 2013 — Cancer metastasis requires tumor cells to acquire properties that allow them to escape from the primary tumor site, travel to a distant place in the body, and form secondary tumors. But first, an advance team of molecules produced by the primary tumor sets off a series of events that create a network of nurturing blood vessels for arriving primary tumor cells to set up shop.In lung cancer, the formation of that niche likely involves immune cells and moderate levels of VEGF and other molecules that promote the formation of new blood vessels, or angiogenesis. But little is known about how the local lining, or endothelial, cells are activated at the niche.Sandra Ryeom, PhD, assistant professor of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, and colleagues, found that the signaling protein calcineurin upregulates another molecule, Ang-2 that promotes the needed angiogenesis. Hyperactivation of calcineurin in genetically altered mice that lack an inhibitior of calcineurin signaling leads to increased lung metastases. Conversely, inhibiting calcineurin or Ang-2 blocked metastases in lung cells of the mice. The findings are published this week in Cell Reports.The findings may help shed light on the underpinnings of common cancer metastasis patterns, such as the tendency of prostate cancer to spread to the bones, or melanoma to the brain.”We demonstrated that the calcineurin pathway is activated specifically in lung endothelium prior to the detection of tumor cells that preferentially and spontaneously metastasize to the lung from our experimental model of flank tumors in mice,” says Ryeom.Also, increased VEGF levels specifically in the lung, and not other organ microenvironments, trigger a threshold amount of calcineurin signaling that activates the Ang2 gene in lung endothelial cells. What’s more, they showed that overexpression of the Ang-2 receptor prevents activation of the lung endothelium and inhibits lung metastases in their mouse models. “Our studies provide insights into the mechanisms underlying angiogenesis in the pre-metastatic niche and offer new targets for lung metastases,” she says. Because calcineurin acts on the pathways that set up sites of metastasis away from the primary tumor sites, it could be a potential target for future cancer therapies; however it is also active in the immune system. …

Read more

Utilizzando il sito, accetti l'utilizzo dei cookie da parte nostra. maggiori informazioni

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close