A one-cubic-foot approach to studying biodiversity as showcased in the new Biocube exhibit at the Smithsonian’s National Museum of Natural History has led to the […]

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The Smithsonian’s National Portrait Gallery celebrates the accomplishments of astronaut and Senator John Glenn (1921-2016) with a watercolor and graphite portrait by Henry C. Caselli […]

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In 1969, 60 to 100 peacock bass imported from Buga, Colombia, were introduced into a pond in Panama for sport fishing. Several individuals escaped. By […]

The post Peacock bass invasion Had devastating, long-term impact on Panama’s Fish appeared first on Smithsonian Insider.

Fat, toxic and nocturnal, cane toads (Rhinella marina) are abundant today in Hawaii, even though they are South American natives. Released on the Hawaiian Islands […]

The post Two invasive species have Hawaiian reunion after 80-year separation appeared first on Smithsonian Insider.

Fast radio bursts (FRBs) are brief spurts of radio emission, lasting just one-thousandth of a second, whose origins are mysterious. Fewer than two dozen have […]

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The search for extraterrestrial intelligence has looked for many different signs of alien life, from radio broadcasts to laser flashes, without success. However, newly published […]

The post Could Fast Radio Bursts Be Powering Alien Probes? appeared first on Smithsonian Insider.

New species don’t just spring out of thin air. Speciation, the evolutionary process by which new and distinct species arise, usually takes millions of years. […]

The post Simultaneous hermaphrodites: Understanding Speciation in fish called “hamlets” appeared first on Smithsonian Insider.

Whales from both poles migrate long distances to breed in tropical waters. Smithsonian scientist Hector M. Guzman and Fernando Félix at the Salinas Whale Museum […]

The post Whale tagging in Southeast Pacific provides data for species protection appeared first on Smithsonian Insider.

Great Cats keepers at the Smithsonian’s National Zoo are celebrating the birth of a Sumatran tiger, a critically endangered species. The cub’s mother, 8-year-old Damai, […]

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Using new numerical simulations and observations, scientists may now be able to explain why the Sun’s magnetic field reverses every eleven years. This significant discovery […]

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The next time you swat a fly ponder this: inside its belly is the DNA of whatever it ate before landing on your picnic dinner—roadkill, […]

The post Innovation: Belly gunk from flies used to survey forest animals appeared first on Smithsonian Insider.

In everyday life, ultraviolet, or UV, light earns a bad reputation for being responsible for sunburns and other harmful effects on humans. However, research suggests […]

The post In search for life, ultraviolet light may be ultra important appeared first on Smithsonian Insider.

Hundreds of experiments have shown biodiversity fosters healthier, more productive ecosystems. But many experts doubted whether these experiments would hold up in the real world. […]

The post In the wild, biodiversity’s power surpasses what experiments predict appeared first on Smithsonian Insider.

When fast radio bursts, or FRBs, were first detected in 2001, astronomers had never seen anything like them before. Since then, astronomers have found a […]

The post New study indicates mysterious fast radio bursts occur in universe every second appeared first on Smithsonian Insider.

This animation shows how binary neutron stars warp space-time to create gravitational waves, then collide and explode into a visible kilonova, which can be detected […]

The post Astronomers see light show associated with gravitational waves appeared first on Smithsonian Insider.

“Probably no genus of birds in the American avifauna has received the amount of attention that has been bestowed upon the turkeys…there has been no […]

The post Happy Thanksgiving! Here are 25 fun turkey-related objects in Smithsonian collections! appeared first on Smithsonian Insider.

The next generation of the Sloan Digital Sky Survey (SDSS-V), directed by Juna Kollmeier of the Carnegie Institution for Science, will move forward with mapping […]

The post Next generation astronomical survey to map the entire sky appeared first on Smithsonian Insider.

According to a new survey of residents living near two major national parks in Panama, jaguars deserve increased protection. Nature and wildlife are considered national […]

The post Jaguar conservation depends on neighbor attitudes appeared first on Smithsonian Insider.

Astronomers had a mystery on their hands. No matter where they looked, from inside the Milky Way to distant galaxies, they observed a puzzling glow […]

The post GBT Detection Unlocks Exploration of ‘Aromatic’ Interstellar Chemistry appeared first on Smithsonian Insider.

Flying through the air? Check. Surviving snake bites? Check. One of the most adorable creatures on earth? Absolutely! Do you think you know everything about […]

The post This Squirrel Appreciation Day we have a few surprising squirrely facts for you appeared first on Smithsonian Insider.

“Somber” is the adjective Smithsonian beetle expert Terry Erwin uses to describe the insects he collects on the forest floor in Peru and Ecuador. “They […]

The post Meet the newest New World canopy beetle species. ‘Gazillions’ await discovery. appeared first on Smithsonian Insider.

The Sun glows with a surface temperature of about 5,500 degrees Celsius (9,932 degrees Fahrenheit). On the other hand its hot outer layer, the corona, […]

The post Magnetic reconnection in the sun appeared first on Smithsonian Insider.

When “2001: A Space Odyssey” premiered April 2, 1968 at Washington, D.C.’s Uptown Theater—not far from the Smithsonian’s National Air and Space Museum—not everyone was […]

The post The real history behind science fiction’s ‘2001: A Space Odyssey’ appeared first on Smithsonian Insider.

Very early on, cockroach moms found out maternal care gave their offspring a better chance at survival. The cockroach parenting method—which includes feeding, guarding and […]

The post Helicopter cockroach moms have protected their young for millions of years appeared first on Smithsonian Insider.

People often use the words turtle and tortoise interchangeably, but these reptiles have distinct differences: Turtle shells are typically more flattened and not as deeply […]

The post Five fun turtle and tortoise facts from the Smithsonian’s National Zoo appeared first on Smithsonian Insider.

Little to nothing is known about how and where a small European songbird called the bluethroat spends much of the year. Now, Smithsonian scientists have […]

The post Scientists track a mysterious songbird using tiny backpack locators appeared first on Smithsonian Insider.

Every queen deserves a castle, and the ruler of the Smithsonian’s National Zoo’s naked mole-rat colony is no different. After 27 years in a maze […]

The post Building a naked mole-rat dream home at the Smithsonian’s National Zoo appeared first on Smithsonian Insider.

When the heat and humidity of the Washington, D.C. summer sends its residents scrambling for air conditioning and iced coffee, the animal care specialists at […]

The post How do National Zoo animals beat the heat? Bloodsicles and other frozen delicacies appeared first on Smithsonian Insider.

Aldo-keto reductases (AKRs) are NADPH/NADP+-dependent oxidoreductase enzymes that metabolize an aldehyde/ketone to the corresponding alcohol. AKR4C14 from rice exhibits a much higher efficiency in metabolizing malondialdehyde (MDA) than do the Arabidopsis enzymes AKR4C8 and AKR4C9, despite sharing greater than 60% amino-acid sequence identity. This study confirms the role of rice AKR4C14 in the detoxification of methylglyoxal and MDA, and demonstrates that the endogenous contents of both aldehydes in transgenic Arabidopsis ectopically expressing AKR4C14 are significantly lower than their levels in the wild type. The apo structure of indica rice AKR4C14 was also determined in the absence of the cofactor, revealing the stabilized open conformation. This is the first crystal structure in AKR subfamily 4C from rice to be observed in the apo form (without bound NADP+). The refined AKR4C14 structure reveals a stabilized open conformation of loop B, suggesting the initial phase prior to cofactor binding. Based on the X-ray crystal structure, the substrate- and cofactor-binding pockets of AKR4C14 are formed by loops A, B, C and β1α1. Moreover, the residues Ser211 and Asn220 on loop B are proposed as the hinge residues that are responsible for conformational alteration while the cofactor binds. The open conformation of loop B is proposed to involve Phe216 pointing out from the cofactor-binding site and the opening of the safety belt. Structural comparison with other AKRs in subfamily 4C emphasizes the role of the substrate-channel wall, consisting of Trp24, Trp115, Tyr206, Phe216, Leu291 and Phe295, in substrate discrimination. In particular, Leu291 could contribute greatly to substrate selectivity, explaining the preference of AKR4C14 for its straight-chain aldehyde substrate.

The biological processes related to protein homeostasis in Mycobacterium tuberculosis, the etiologic agent of tuberculosis, have recently been established as critical pathways for therapeutic intervention. Proteins of particular interest are ClpC1 and the ClpC1–ClpP1–ClpP2 proteasome complex. The structure of the potent antituberculosis macrocyclic depsipeptide ecumicin complexed with the N-terminal domain of ClpC1 (ClpC1-NTD) is presented here. Crystals of the ClpC1-NTD–ecumicin complex were monoclinic (unit-cell parameters a = 80.0, b = 130.0, c = 112.0 Å, β = 90.07°; space group P21; 12 complexes per asymmetric unit) and diffracted to 2.5 Å resolution. The structure was solved by molecular replacement using the self-rotation function to resolve space-group ambiguities. The new structure of the ecumicin complex showed a unique 1:2 (target:ligand) stoichiometry exploiting the intramolecular dyad in the α-helical fold of the target N-terminal domain. The structure of the ecumicin complex unveiled extensive interactions in the uniquely extended N-terminus, a critical binding site for the known cyclopeptide complexes. This structure, in comparison with the previously reported rufomycin I complex, revealed unique features that could be relevant for understanding the mechanism of action of these potential antituberculosis drug leads. Comparison of the ecumicin complex and the ClpC1-NTD-L92S/L96P double-mutant structure with the available structures of rufomycin I and cyclomarin A complexes revealed a range of conformational changes available to this small N-terminal helical domain and the minor helical alterations involved in the antibiotic-resistance mechanism. The different modes of binding and structural alterations could be related to distinct modes of action.

Death-associated protein kinase 1 (DAPK1) is a serine/threonine protein kinase that regulates apoptosis and autophagy. DAPK1 is considered to be a therapeutic target for amyloid-β deposition, endometrial adenocarcinomas and acute ischemic stroke. Here, the potent inhibitory activity of the natural anthraquinone purpurin against DAPK1 phosphorylation is shown. Thermodynamic analysis revealed that while the binding affinity of purpurin is similar to that of CPR005231, which is a DAPK1 inhibitor with an imidazopyridazine moiety, the binding of purpurin was more enthalpically favorable. In addition, the inhibition potencies were correlated with the enthalpic changes but not with the binding affinities. Crystallographic analysis of the DAPK1–purpurin complex revealed that the formation of a hydrogen-bond network is likely to contribute to the favorable enthalpic changes and that stabilization of the glycine-rich loop may cause less favorable entropic changes. The present findings indicate that purpurin may be a good lead compound for the discovery of inhibitors of DAPK1, and the observation of enthalpic changes could provide important clues for drug development.

Mycoplasma hyopneumoniae is a prokaryotic pathogen that colonizes the respiratory ciliated epithelial cells in swine. Infected animals suffer respiratory lesions, causing major economic losses in the porcine industry. Characterization of the immunodominant membrane-associated proteins from M. hyopneumoniae may be instrumental in the development of new therapeutic approaches. Here, the crystal structure of P46, one of the main surface-antigen proteins, from M. hyopneumoniae is presented and shows N- and C-terminal α/β domains connected by a hinge. The structures solved in this work include a ligand-free open form of P46 (3.1 Å resolution) and two ligand-bound structures of P46 with maltose (2.5 Å resolution) and xylose (3.5 Å resolution) in open and closed conformations, respectively. The ligand-binding site is buried in the cleft between the domains at the hinge region. The two domains of P46 can rotate with respect to each other, giving open or closed alternative conformations. In agreement with this structural information, sequence analyses show similarities to substrate-binding members of the ABC transporter superfamily, with P46 facing the extracellular side as a functional subunit. In the structure with xylose, P46 was also bound to a high-affinity (Kd = 29 nM) Fab fragment from a monoclonal antibody, allowing the characterization of a structural epitope in P46 that exclusively involves residues from the C-terminal domain. The Fab structure in the complex with P46 shows only small conformational rearrangements in the six complementarity-determining regions (CDRs) with respect to the unbound Fab (the structure of which is also determined in this work at 1.95 Å resolution). The structural information that is now available should contribute to a better understanding of sugar nutrient intake by M. hyopneumoniae. This information will also allow the design of protocols and strategies for the generation of new vaccines against this important swine pathogen.

Leucocyte common antigen-related protein (LAR) is a post-synaptic type I transmembrane receptor protein that is important for neuronal functionality and is genetically coupled to neuronal disorders such as attention deficit hyperactivity disorder (ADHD). To understand the molecular function of LAR, structural and biochemical studies of protein fragments derived from the ectodomain of human LAR have been performed. The crystal structure of a fragment encompassing the first four FNIII domains (LARFN1–4) showed a characteristic L shape. SAXS data suggested limited flexibility within LARFN1–4, while rigid-body refinement of the SAXS data using the X-ray-derived atomic model showed a smaller angle between the domains defining the L shape compared with the crystal structure. The capabilities of the individual LAR fragments to interact with heparin was examined using microscale thermophoresis and heparin-affinity chromatography. The results showed that the three N-terminal immunoglobulin domains (LARIg1–3) and the four C-terminal FNIII domains (LARFN5–8) both bound heparin, while LARFN1–4 did not. The low-molecular-weight heparin drug Innohep induced a shift in hydrodynamic volume as assessed by size-exclusion chromatography of LARIg1–3 and LARFN5–8, while the chemically defined pentameric heparin drug Arixtra did not. Together, the presented results suggest the presence of an additional heparin-binding site in human LAR.

Despite the importance of seasonally dry forests, little is known of their ecology. Now, a new book The Ecology and Conservation of Seasonally Dry Forests in Asia, published by Smithsonian Institution Scholarly Press, explores these unique ecosystems, its animals, plants, and the people that inhabit them.

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Now, for the first time, Charles Darwin's life is portrayed pictorially in an illustrated biography in graphic novel-style for all ages to enjoy.

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Between the world wars of the early Twentieth Century, an age of adventure travel and cultural exploration flourished when newly developed transport and recording technologies–particularly […]

The post New Book: “Recreating First Contact: Expeditions, Anthropology, and Popular Culture” appeared first on Smithsonian Insider.

For the first time in its history the Smithsonian’s National Museum of African Art opened an exhibition on the continent of Africa. “Chief S.O. Alonge: […]

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Yinlong Song, Yikan Zhang, Ying Pan, Jianfeng He, Yan Wang, Wei Chen, Jing Guo, Haiteng Deng, Yi Xue, Xianyang Fang, and Xin Liang

Microtubules dynamics is regulated by the plus end-tracking proteins (+TIPs) in cells. End binding protein 1 (EB1) acts as a master regulator in +TIPs networks by targeting microtubule growing ends and recruiting other factors. However, the molecular mechanism of how EB1 binds to microtubule ends with a high affinity remains to be an open question. Using single-molecule imaging, we show that the end-binding kinetics of EB1 changes along with the polymerizing and hydrolysis rate of tubulin dimers, confirming the binding of EB1 to GTP/GDP-Pi tubulin at microtubule growing ends. The affinity of wild-type EB1 to these sites is higher than monomeric EB1 mutants, suggesting that two CH domains in the dimer contribute to the end-binding. Introducing phosphomimicking mutations into the linker domain of EB1 weakens the end-binding affinity and confers a more curved conformation to EB1 dimer without compromising dimerization, suggesting that the overall architecture of EB1 is important for the end-binding affinity. Taken together, our results provide insights into understanding how the high-affinity end-binding of EB1 can be achieved and how this activity may be regulated in cells.

Imke K. Mandemaker, Di Zhou, Serena T. Bruens, Dick H. Dekkers, Pernette J. Verschure, Raghu R. Edupuganti, Eran Meshorer, Jeroen A. Demmers, and Jurgen A. Marteijn

Many chromatin remodeling and modifying proteins are involved in the DNA damage response by stimulating repair or inducing DNA damage signaling. Interestingly, here we identified that down regulation of the H1-interacting protein SET results in increased resistance to a wide variety of DNA damaging agents. We found that this increased resistance is not the result of an inhibitory effect of SET on DNA repair, but rather the consequence of a suppressed apoptotic response to DNA damage. We further provide evidence that the histone chaperone SET is responsible for the eviction of H1 from chromatin. Knock down of H1 in SET-depleted cells resulted in re-sensitization of cells to DNA damage, suggesting that the increased DNA damage resistance in SET-depleted cells is the result of enhanced retention of H1 on chromatin. Finally, clonogenic survival assays show that SET and p53 are epistatic in attenuating DNA damage-induced cell death. Altogether, our data show a role for SET in the DNA damage response as a regulator of cell survival following genotoxic stress.