Galaxies are sometimes found in large clusters with many hundreds of members. Typically there is a giant elliptical galaxy near the center; most of these ellipticals are very bright emitters of radio radiation as a result of activity around supermassive black holes at their nuclei.
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A description and photos of the green-headed tanager (Tangara seledon), a bird native to east-central South America, can be found in the Species of the […]
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Smithsonian scientists have confirmed that chytridiomycosis, a rapidly spreading amphibian disease, has reached a site near Panama’s Darien region. This was the last area in the entire mountainous neotropics to be free of the disease. This is troubling news for the Panama Amphibian Rescue and Conservation Project, a consortium of nine U.S. and Panamanian institutions that aims to rescue 20 species of frogs in imminent danger of extinction.
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A team of researchers has for the first time mapped the above ground carbon density of an entire country in high fidelity. They integrated field […]
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Have you ever had a pet that seemed just a little bit crazy or odd? Can you be sure that it was in control of […]
The post Crazy eyes and mind control – the power of parasites appeared first on Smithsonian Insider.
Most people think of black holes as giant vacuum cleaners sucking in everything that gets too close. But the supermassive black holes at the centers […]
The post Event Horizon Telescope Reveals Magnetic Fields at Milky Way’s Central Black Hole appeared first on Smithsonian Insider.
For the first time, scimitar-horned oryx are going to be reintroduced to the wild in Chad. Extinct in the wild since the mid-1980s, the species’ […]
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Only the Wing is a new book by Russell Lee that recounts Horten's epic quest to stabalize and control the all-wing aircraft.
The post New Book: “Only the Wing: Reimar Horten’s Epic Quest to Stabilize and Control the All-Wing Aircraft” appeared first on Smithsonian Insider.
Yung-An Huang, Chih-Hsuan Hsu, Ho-Chieh Chiu, Pei-Yu Hsi, Chris T. Ho, Wei-Lun Lo, and Eric Hwang
Microtubule (MT) is the most abundant cytoskeleton in neurons and controls multiple facets of their development. While the MT-organizing center (MTOC) in mitotic cells is typically located at the centrosome, MTOC in neurons switches to non-centrosomal sites. A handful of cellular components have been shown to promote non-centrosomal MT (ncMT) formation in neurons, yet the regulation mechanism remains unknown. Here we demonstrate that the small GTPase Ran is a key regulator of ncMTs in neurons. Using an optogenetic tool that enables light-induced local production of RanGTP, we demonstrate that RanGTP promotes ncMT plus-end growth along the neurite. Additionally, we discovered that actin waves drive the anterograde transport of RanGTP. Pharmacological disruption of actin waves abolishes the enrichment of RanGTP and reduces growing ncMT plus-ends at the neurite tip. These observations identify a novel regulation mechanism of ncMTs and pinpoint an indirect connection between the actin and MT cytoskeletons in neurons.
Osiris Martinez-Guzman, Mathilda M. Willoughby, Arushi Saini, Jonathan V. Dietz, Iryna Bohovych, Amy E. Medlock, Oleh Khalimonchuk, and Amit R. Reddi
Heme is a cofactor and signaling molecule that is essential for much of aerobic life. All heme-dependent processes in eukaryotes require that heme is trafficked from its site of synthesis in the mitochondria to hemoproteins located throughout the cell. However, the mechanisms governing the mobilization of heme out of the mitochondria, and the spatio-temporal dynamics of these processes, are poorly understood. Herein, using genetically encoded fluorescent heme sensors, we developed a live cell assay to monitor heme distribution dynamics between the mitochondrial inner-membrane, where heme is synthesized, and the mitochondrial matrix, cytosol, and nucleus. Surprisingly, heme trafficking to the nucleus is ~25% faster than to the cytosol or mitochondrial matrix, which are nearly identical, potentially supporting a role for heme as a mitochondrial-nuclear retrograde signal. Moreover, we discovered that the heme synthetic enzyme, 5-aminolevulinic acid synthase (ALAS), and GTPases in control of the mitochondrial dynamics machinery, Mgm1 and Dnm1, and ER contact sites, Gem1, regulate the flow of heme between the mitochondria and nucleus. Overall, our results indicate that there are parallel pathways for the distribution of bioavailable heme.
Hem Sapkota, Jonathan D. Wren, and Gary J. Gorbsky
Centrosomes focus microtubules to promote mitotic spindle bipolarity, a critical requirement for balanced chromosome segregation. Comprehensive understanding of centrosome function and regulation requires a complete inventory of components. While many centrosome components have been identified, others may yet remain undiscovered. We have used a bioinformatics approach, based on "guilt by association" expression to identify novel mitotic components among the large group of predicted human proteins that have yet to be functionally characterized. Here we identify Chondrosarcoma-Associated Gene 1 (CSAG1) in maintaining centrosome integrity during mitosis. Depletion of CSAG1 disrupts centrosomes and leads to multipolar spindles more effectively in cells with compromised p53 function. Thus, CSAG1 may reflect a class of "mitotic addiction" genes whose expression is more essential in transformed cells.
Aline A. Alves, Heloisa B. Gabriel, Maria J. R. Bezerra, Wanderley de Souza, Sue Vaughan, Narcisa L. Cunha-e-Silva, and Jack D. Sunter
Eukaryotic flagella are complex microtubule based organelles and in many organisms there are extra-axonemal structures present, including the outer dense fibres of mammalian sperm and the paraflagellar rod (PFR) of trypanosomes. Flagellum assembly is a complex process occurring across three main compartments, the cytoplasm, the transition fibre-transition zone, and the flagellum. It begins with translation of protein components, followed by their sorting and trafficking into the flagellum, transport to the assembly site and then incorporation. Flagella are formed from over 500 proteins; the principles governing axonemal component assembly are relatively clear. However, the coordination and sites of extra-axonemal structure assembly processes are less clear.
We have discovered two cytoplasmic proteins in T. brucei that are required for PFR formation, PFR assembly factors 1 and 2. Deletion of either PFR-AF1 or PFR-AF2 dramatically disrupted PFR formation and caused a reduction in the amount of major PFR proteins. The presence of cytoplasmic factors required for PFR formation aligns with the concept of processes occurring across multiple compartments to facilitate axoneme assembly and this is likely a common theme for extra-axonemal structure assembly.
Tara L. Mastro, Vishnu P. Tripathi, and Susan L. Forsburg
Translesion synthesis polymerases (TLSPs) are non-essential error-prone enzymes that ensure cell survival by facilitating DNA replication in the presence of DNA damage. In addition to their role in bypassing lesions, TLSPs have been implicated in meiotic double strand break repair in several systems. Here we examine the joint contribution of four TLS polymerases to meiotic progression in the fission yeast S. pombe. We observed the dramatic loss of spore viability in fission yeast lacking all four TLSPs which is accompanied by disruptions in chromosome segregation during meiosis I and II. Rec8 cohesin dynamics are altered in the absence of the TLSPs. These data suggest that the TLSPs contribute to multiple aspects of meiotic chromosome dynamics.
Sanjeev Chavan Nayak and Vegesna Radha
C3G (RapGEF1) plays a role in cell differentiation and is essential for early embryonic development in mice. In this study, we identify C3G as a centrosomal protein colocalizing with cenexin at the mother centriole in interphase cells. C3G interacts through its catalytic domain with cenexin, and they show interdependence for localization to the centrosome. C3G depletion caused a decrease in cellular cenexin levels. Centrosomal localization is lost as myocytes differentiate to form myotubes. Stable clone of cells depleted of C3G by CRISPR/Cas9 showed the presence of supernumerary centrioles. Overexpression of C3G, or a catalytically active deletion construct inhibited centrosome duplication. Cilia length is longer in C3G knockout cells, and the phenotype could be reverted upon reintroduction of C3G or its catalytic domain. Association of C3G with the basal body is dynamic, decreasing upon serum starvation, and increasing upon reentry into the cell cycle. C3G inhibits cilia formation and length dependent on its catalytic activity. We conclude that C3G inhibits centrosome duplication and maintains ciliary homeostasis, properties that may be important for its role in embryonic development.
The humble salamander may provide evidence to support a controversial claim that North and South America were joined together much earlier than previously thought. The […]
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X-ray emission under electron-channelling conditions is used to distinguish between a non-centrosymmetric half-Heusler and a centrosymmetric full-Heusler crystal. For TiCo1.5+xSn the space-group determination based on a Rietveld refinement procedure became challenging for increasing Co content (x > 0.2), while electron channelling proved successful for higher Co content (x = 0.35). This technique can be used on crystals as small as (10 nm)3.
Food is an important element of Basque life. In the Ostatua Kitchen tent at the Smithsonian’s 2016 Folklife Festival, chefs from two Basque culinary schools […]
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Plants are among the world’s best carbon sinks, but there’s a side to the plant-CO2 love affair that’s rarely discussed. When carbon dioxide rises, plants […]
The post The strange, controversial way plants trap CO2 appeared first on Smithsonian Insider.
Ubiquitous as they may be today, the origin of the Christmas tree is unknown to most. The tradition of decorating a tree, usually an evergreen […]
The post Agustín Stahl: Scientist Who Introduced the “Arbol de Navidad” (Christmas Tree) to Puerto Rico appeared first on Smithsonian Insider.
Melinda Peters, museum specialist at the U.S. National Herbarium in the Smithsonian’s National Museum of Natural History, gives an in-depth tour of the U.S. National […]
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By now, most of the United States has started to feel the first cool caresses of winter. Everything is pumpkin spiced, and the last crickets […]
The post Feathered diplomats unite pupils in North and Central America appeared first on Smithsonian Insider.
Corn, known also as maize, is a vital crop in the U.S. and throughout the Americas. First domesticated in Mexico some 9,000 years ago, scientists […]
The post Study dates corn as staple crop in Central America beginning 4,300 years ago appeared first on Smithsonian Insider.
UTLA says it is at an impasse with the Los Angeles Unified School District over a new contract for its 31,000 teachers. ; Credit: File photo by Letsdance Tonightaway/Flickr Creative Commons
Sandra OshiroThe United Teachers Los Angeles declared an impasse Wednesday in its talks with the Los Angeles Unified School District.
The action opens the way for a mediator to be brought in to help bring about a settlement.
Contract talks have been ongoing since July, UTLA said on its website.
"There is still a significant gap between the two sides on compensation," the union stated. UTLA is seeking an 8.5 percent, one-year increase; LAUSD has offered a 5 percent increase.
The union said the district is "refusing to bargain in good faith on student learning conditions, and threatening educator layoffs as a scare tactic."
LAUSD Superintendent Ramon Cortines said in a statement that the district agrees the talks are at an impasse.
"I've been disappointed and frustrated by the lack of progress toward an agreement," he said. "It's my hope that the appointment of a mediator will lead to an expeditious settlement that ultimately supports our students and the District at large."
UTLA represents 31,000 members, including teachers and health and human service professionals.
The differences between the two sides amount to more than $800 million, the district said in its statement. Cortines has maintained that the district is facing a deficit. The union insists the district has money.
Other issues dividing the two sides include class room size and teacher evaluations.
This content is from Southern California Public Radio. View the original story at SCPR.org.
At a recent LAUSD District 3 school board debate, teachers dressed as FBI agents in protest of board member Tamar Galatzan's support of the iPad program.; Credit: Annie Gilbertson/KPCC
Annie GilbertsonAs the city's March 3 primary election draws near, Los Angeles Unified school board candidates are blasting incumbents for the controversial iPad program.
Opponents sharply criticized the $1.3 billion bond-funded program at a debate Tuesday in West San Fernando Valley, where District 3 school board member Tamar Galatzan was elected in 2007.
"Galatzan said the district is going in the right direction," declared candidate Carl Petersen, a parent and businessman. "I don’t know how anyone can look at the events of the past year and come to that conclusion."
RELATED: LAUSD District 5 school board candidates face off in debate
The program attracted national attention last December when the FBI raided district offices and carted off 20 boxes of bids, evaluations and correspondences with executives at Apple and its subcontractor Pearson, the manufacturer of the learning software loaded on to each device. The investigation is ongoing.
At the debate, teachers dressed in dark windbreakers with FBI plastered on the back in protest to Galatzan's support of the program. (They have not held similar demonstrations at election events in East Los Angeles' District 5, where Bennett Kayser, a teacher union ally, is running for re-election.)
Tom Richards, a Granada Hills parent, said he considers the iPad program a central issue as he weighs candidates.
"I think it's absolutely ridiculous," Richards said. "I don't believe that's a good way to spend the money that they have. Looking at some really fundamental needs — we don't have a librarian, but we want to give iPads?"
Galatzan was an early advocate for more technology in the classroom; it was her goal even before the iPad was on the market.
"There is a whole world out there that can be accessed through technology, and we need to take advantage of that," Galatzan told KPCC.
Her advocacy of technology hasn't always been controversial. Galatzan points to her 2010 initiative to fund school computer labs with a settlement from Microsoft.
The school board's support of the iPad program varied the first year, but waned in August after KPCC published a series of emails showing district administrators had close ties with Pearson, calling into question whether the bidding process was fair. Problems with the rollout of the devices and the effectiveness of the software they contained also eroded support for the program.
Still, school board members unanimously approved more iPad purchases after the FBI investigation came to light. Superintendent Ramon Cortines said the tablets were necessary for new digital state tests scheduled this spring and offered to purchase them under a different contract with Apple to avoid complications involving the federal probe.
If the candidates' positions are a measure of support for the program, it's unpopular at best. All of Galatzan's opponents are against it.
When asked in a KPCC election survey conducted if he supported the iPad program, Scott Schmerelson, a retired administrator and District 3 contender, responded: "Not when you are paying for them from LAUSD Bond Money! The taxpayers generously supported the bond issue with the belief that the money would be used to repair and modernize our schools."
Candidate Ankur Patel said in his answer to the survey, "I oppose the LAUSD’s iPad program. Throughout the program, important questions were not asked enough, and when they were, they were not answered properly."
Filiberto Gonzalez, another Galatzan challenger, said of the iPad project: "It was a mistake and ill-conceived from the very beginning. As was noted in the report by the U.S. Department of Education last month, the Common Core Technology Project (iPad program) lacked 'established metrics of success' and 'was difficult to show the impact of the investment.'
Elizabeth Badger Bartels is also running for the District 3 seat, but did not respond to the survey by deadline.
For more information on the school board candidates' positions and their backgrounds, read KPCC's 2015 Los Angeles primary election guide.
This content is from Southern California Public Radio. View the original story at SCPR.org.
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National Science Foundation (NSF)-funded researchers from North Carolina State and Elon universities have developed a technique that allows them to remotely control the movement of soft robots, lock them into position for as long as needed and later reconfigure the robots into new shapes. The technique relies on light and magnetic fields. "By engineering the properties of the material, we can control the soft robot's movement remotely; we can get it to hold a given shape; we can then return the robot to its original shape or further modify its movement; and we can do this repeatedly. All of those things are valuable, in terms of this technology's utility in biomedical or aerospace applications," says Joe Tracy, a professor of materials science and engineering at NC State and corresponding author of a paper on the work. In experimental testing, the researchers demonstrated that the soft robots could be used to form "grabbers" for lifting and transporting objects. The soft robots could also be used as cantilevers or folded into "flowers" with petals that bend in different directions. "We are not limited to binary configurations, such as a grabber being either open or closed," says Jessica Liu, first author of the paper and a Ph.D. student at NC State. "We can control the light to ensure that a robot will hold its shape at any point."
Image credit: Jessica A.C. Liu
More targeted aircraft testing and simulation should be conducted to uncover design characteristics in new flight control systems that -- in rare circumstances -- may mislead pilots and result in unstable or dangerous flight conditions, says a new report by a National Research Council committee.
Smokers who are exposed to radon appear to be at even greater risk for lung cancer, because the effects of smoking and radon are more powerful when the two factors are combined, says a new report by a committee of the National Research Council.
Bacteria that resist antibiotics can be passed from food animals to humans, but not enough is known to determine the public health risks posed by such transmission, says a new report by a committee of the National Research Council.
On average, Americans die sooner and experience higher rates of disease and injury than people in other high-income countries, says a new report from the National Research Council and Institute of Medicine.
Given the minimal impact of long prison sentences on crime prevention and the negative social consequences and burdensome financial costs of U.S. incarceration rates, which have more than quadrupled in the last four decades, the nation should revise current criminal justice policies to significantly reduce imprisonment rates, says a new report from the National Research Council.
The U.S. Environmental Protection Agency (EPA) carries out experiments in which volunteer participants agree to be intentionally exposed by inhalation to specific pollutants at restricted concentrations over short periods to obtain important information about the effects of outdoor air pollution on human health.
In an August 18 letter, the U.S. Department of the Interior’s Office of Surface Mining Reclamation and Enforcement informed the National Academies of Sciences, Engineering, and Medicine that it should cease all work on a study of the potential health risks for people living near surface coal mine sites in Central Appalachia.
Despite progress in recent decades, more than 10,000 alcohol-impaired driving fatalities occur each year in the U.S. To address this persistent problem, stakeholders -- from transportation systems to alcohol retailers to law enforcement -- should work together to implement policies and systems to eliminate these preventable deaths, says a new report from the National Academies of Sciences, Engineering, and Medicine.
The emergence of inexpensive small unmanned aircraft systems (sUASs) that operate without a human pilot, commonly known as drones, has led to adversarial groups threatening deployed U.S. forces, especially infantry units.
The Gulf Research Program (GRP) of the National Academies of Sciences, Engineering, and Medicine is collaborating with the Sea Grant Oil Spill Science Outreach Program to convene a series of workshops aimed at improving community preparedness for future oil spills.
Recent gains against the burden of illness, injury, and disability and commitment to universal health coverage (UHC) are insufficient to close the enormous gaps that remain between what is achievable in human health and where global health stands today, says a new report from the National Academies of Sciences, Engineering, and Medicine.
Current cancer control efforts in the United States typically are fragmented and uncoordinated, but taking a systems approach to establish a U.S. National Cancer Control Plan would address the challenge more holistically, says a new report from the National Academies of Sciences, Engineering, and Medicine.
PFAS, or perfluoroalkyl and polyfluoroalkyl substances, are ubiquitous fluorinated organic compounds found widely in manufactured products, from firefighting foam to stain-resistant carpets. These water- and oil-repellent compounds are known to degrade slowly over time, and have been found in humans, drinking water, and even in Arctic ecosystems.