Scientists studying genetic variation and gene flow in a population of tortoises (Gopherus agassizii) in California’s Mojave Desert, were surprised recently to discover that two roads built in the desert in the 1970s had a noticeable impact on the population’s genetic structure.

The post Why did the tortoise cross the road? A recent study indicates few do. appeared first on Smithsonian Insider.

A new X-ray study of the remains of an exploded star indicates that the supernova that disrupted the massive star may have turned it inside out in the process.

The post Remains of exploded star indicate supernova turned it inside out appeared first on Smithsonian Insider.

The only explanation for such symmetry across these vast distances, explains Smithsonian anthropologist Dennis Stanford, is that the method of creating the points was handed down from person to person.

The post 3-D imaging adds remarkable new understanding of North America’s mysterious Clovis people appeared first on Smithsonian Insider.

Clearly visible connecting the dark-purple cephalopods was the white “terminal organ” or penis of the male, extending out through the male’s funnel.

The post First detailed sex video of deep-sea squid resolves long-standing mysteries as to how these animals mate appeared first on Smithsonian Insider.

The process of freezing materials such as fertilized eggs – cryopreservation – provides researchers with a tool to repopulate endangered species.

The post Klondike, puppy born from a frozen embryo, fetches good news for endangered animals appeared first on Smithsonian Insider.

Detecting alien worlds presents a significant challenge since they are small, faint, and close to their stars. The two most prolific techniques for finding exoplanets […]

The post New method of finding planets scores first discovery appeared first on Smithsonian Insider.

As economic expansion and development fragments the forest landscape of central India, the species that rely on that habitat—including endangered tigers and leopards—face dwindling populations […]

The post Forest corridors essential to gene flow in India’s leopard and tiger populations appeared first on Smithsonian Insider.

Humanity is on the threshold of being able to detect signs of alien life on other worlds. By studying exoplanet atmospheres, we can look for […]

The post Finding ET by searching for alien air pollution appeared first on Smithsonian Insider.

Native Americans and America’s early colonists ate many more blue crabs than modern researchers previously thought, according to a team of scientists studying crab remains […]

The post American Indians, colonists had healthy appetite for crabs, study shows appeared first on Smithsonian Insider.

While studying the social dynamics of the bearded saki, a primate living in the rainforests of Suriname, primatologist Tremaine Gregory of the Smithsonian Conservation Biology […]

The post Study: Male bonding brings peace, lets primates live in big groups appeared first on Smithsonian Insider.

The Smithsonian is embarking on a multi-project partnership with Kickstarter, the funding platform for creative projects. The inaugural project will support conservation of Neil Armstrong’s […]

The post Kickstarter funding: Neil Armstrong’s Apollo 11 spacesuit appeared first on Smithsonian Insider.

Thanks to a recent reassessment of specimens preserved in jars of alcohol at the Smithsonian’s National Museum of Natural History, New Hampshire is now on […]

The post Discovery in Smithsonian collection broadens understanding of rare North American leech appeared first on Smithsonian Insider.

NASA’s InSight probe, scheduled to land on the surface of Mars in November 2018, will be boring. Boring a hole, that is. It will drill […]

The post ISO: a boring Martian landing spot for NASA’s InSight probe 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.

Finding clean ways to store water is a challenge that humans have faced for millennia. In a new paper in Environmental Health, anthropologist Sabrina Sholts […]

The post Study shows ancient California Indians risked toxins from bitumen-coated bottles 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.

Today’s cutting-edge laboratories rely on ultra-cold refrigeration to keep delicate cells like sperm viable for use in the future. But a new technique using microwaves […]

The post What does candied, microwaved sperm have to do with saving endangered species? appeared first on Smithsonian Insider.

A new study from the Smithsonian Conservation Biology Institute (SCBI) is helping make headway in an area of animal management that has historically proven challenging: […]

The post Early indicator of cheetah pregnancy identified appeared first on Smithsonian Insider.

The outer membrane of Gram-negative bacteria is highly impermeable to hydrophilic molecules of larger than 600 Da, protecting these bacteria from toxins present in the environment. In order to transport nutrients across this impermeable membrane, Gram-negative bacteria utilize a diverse family of outer-membrane proteins called TonB-dependent transporters. The majority of the members of this family transport iron-containing substrates. However, it is becoming increasingly clear that TonB-dependent transporters target chemically diverse substrates. In this work, the structure and phylogenetic distribution of the TonB-dependent transporter YncD are investigated. It is shown that while YncD is present in some enteropathogens, including Escherichia coli and Salmonella spp., it is also widespread in Gammaproteobacteria and Betaproteobacteria of environmental origin. The structure of YncD was determined, showing that despite a distant evolutionary relationship, it shares structural features with the ferric citrate transporter FecA, including a compact positively charged substrate-binding site. Despite these shared features, it is shown that YncD does not contribute to the growth of E. coli in pure culture under iron-limiting conditions or with ferric citrate as an iron source. Previous studies of transcriptional regulation in E. coli show that YncD is not induced under iron-limiting conditions and is unresponsive to the ferric uptake regulator (Fur). These observations, combined with the data presented here, suggest that YncD is not responsible for the transport of an iron-containing substrate.

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.

Pullulanase (EC 3.2.1.41) is a well known starch-debranching enzyme that catalyzes the cleavage of α-1,6-glycosidic linkages in α-glucans such as starch and pullulan. Crystal structures of a type I pullulanase from Paenibacillus barengoltzii (PbPulA) and of PbPulA in complex with maltopentaose (G5), maltohexaose (G6)/α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) were determined in order to better understand substrate binding to this enzyme. PbPulA belongs to glycoside hydrolase (GH) family 13 subfamily 14 and is composed of three domains (CBM48, A and C). Three carbohydrate-binding sites identified in PbPulA were located in CBM48, near the active site and in domain C, respectively. The binding site in CBM48 was specific for β-CD, while that in domain C has not been reported for other pullulanases. The domain C binding site had higher affinity for α-CD than for G6; a small motif (FGGEH) seemed to be one of the major determinants for carbohydrate binding in this domain. Structure-based mutations of several surface-exposed aromatic residues in CBM48 and domain C had a debilitating effect on the activity of the enzyme. These results suggest that both CBM48 and domain C play a role in binding substrates. The crystal forms described contribute to the understanding of pullulanase domain–carbohydrate interactions.

The new book Subsistence Economies of Indigenous North American Societies provides a comprehensive and in-depth documentation of how Native American societies met the challenges of […]

The post New book: “The Subsistence Economies of Indigenous North American Societies: A Handbook” appeared first on Smithsonian Insider.

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.

During a press conference Friday, July 22 at the Smithsonian's National Air and Space Museum, NASA announced that Gale Crater will be the landing site for the Mars Science Laboratory. Scheduled to launch in late 2011 and arrive at Mars in August 2012, the Mars Science Laboratory is a rover that will assess the planet’s “habitability”—if it ever was, or is today, an environment able to support microbial life.

The post Gale Crater to be landing site for NASA’s Mars Science Laboratory appeared first on Smithsonian Insider.

Looking for another Earth? An international team of researchers has pinpointed which of the more than 4,000 exoplanets discovered by NASA’s Kepler mission are most […]

The post Another Earth? Kepler astronomers pinpoint likeliest candidates appeared first on Smithsonian Insider.

Serial crystallography records still diffraction patterns from single, randomly oriented crystals, then merges data from hundreds or thousands of them to form a complete data set. To process the data, the diffraction patterns must first be indexed, equivalent to determining the orientation of each crystal. A novel automatic indexing algorithm is presented, which in tests usually gives significantly higher indexing rates than alternative programs currently available for this task. The algorithm does not require prior knowledge of the lattice parameters but can make use of that information if provided, and also allows indexing of diffraction patterns generated by several crystals in the beam. Cases with a small number of Bragg spots per pattern appear to particularly benefit from the new approach. The algorithm has been implemented and optimized for fast execution, making it suitable for real-time feedback during serial crystallography experiments. It is implemented in an open-source C++ library and distributed under the LGPLv3 licence. An interface to it has been added to the CrystFEL software suite.

The post Smithsonian anthropologist JoAllyn Archambault speaks about the outstanding research of 19th-century anthropologist James Mooney appeared first on Smithsonian Insider.

The post Smithsonian conservators open 2001 Jim Thorpe Wheaties Box from the Smithsonian’s National Museum of the American Indian appeared first on Smithsonian Insider.

The post Conrad Labandiera, Smithsonian palentologist, studies fossils to learn how insects got along before flowering plants arrived appeared first on Smithsonian Insider.

This scientific visualization is much more than a dizzying dance of whirling worlds. It shows 2,299 planets found by NASA’s Kepler planet-hunting spacecraft.

The post Animation: Dizzying dance of the Kepler candidates appeared first on Smithsonian Insider.

Identifying and understanding the migratory connectivity of birds throughout an entire annual cycle (not just the times of year they are in your back yard), […]

The post Video: Protecting songbirds by Better Understanding their Migratory connectivity appeared first on Smithsonian Insider.

As American power and population grew in the 19th century, the United States gradually rejected the main principle of treaty-making—that tribes were self-governing nations—and initiated […]

The post The “Indian Problem” appeared first on Smithsonian Insider.

Judy Garland’s iconic ruby slippers from “The Wizard of Oz” are one of the most popular attractions at the National Museum of American History. But […]

The post Crowdfunding campaign to restore Ruby Slippers surpasses mark appeared first on Smithsonian Insider.

Part 1 – Public Programs Coordinator Gloria Kenyon demonstrates crafting for the next Handi Hour program at the Renwick Gallery of the Smithsonian American Art […]

The post Handi-hour crafting – Cross Stitch Embroidery appeared first on Smithsonian Insider.

They’ve got no roots or veins and grow in hanging pendants or tightly packed mats attached to stones, soil and wood. Called by some “the […]

The post Mosses have strong potential to acclimate to global warming, study indicates appeared first on Smithsonian Insider.

Long before colonists landed on the shores of New England, Native Americans harvested cranberries from peaty bogs and marshes. Following the Pilgrims reliance on the […]

The post The cranberry: America’s founding fruit appeared first on Smithsonian Insider.

An elementary method is described for finding the coordination sequences for a tiling, based on coloring the underlying graph. The first application is to the two kinds of vertices (tetravalent and trivalent) in the Cairo (or dual-32.4.3.4) tiling. The coordination sequence for a tetravalent vertex turns out, surprisingly, to be 1, 4, 8, 12, 16, …, the same as for a vertex in the familiar square (or 44) tiling. The authors thought that such a simple fact should have a simple proof, and this article is the result. The method is also used to obtain coordination sequences for the 32.4.3.4, 3.4.6.4, 4.82, 3.122 and 34.6 uniform tilings, and the snub-632 tiling. In several cases the results provide proofs for previously conjectured formulas.

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The crystal structure of tri­phenyl­methanol, C19H16O, has been redetermined using data collected at 295 and 153 K, and is compared to the model published by Ferguson et al. over 25 years ago [Ferguson et al. (1992). Acta Cryst. C48, 1272–1275] and that published by Serrano-González et al., using neutron and X-ray diffraction data [Serrano-González et al. (1999). J. Phys. Chem. B, 103, 6215–6223]. As predicted by these authors, the hy­droxy groups are involved in weak inter­molecular hydrogen bonds in the crystal, forming tetra­hedral tetra­­mers based on the two independent mol­ecules in the asymmetric unit, one of which is placed on the threefold symmetry axis of the Roverline{3} space group. However, the reliable determination of the hy­droxy H-atom positions is difficult to achieve, for two reasons. Firstly, a positional disorder affects the full asymmetric unit, which is split over two sets of positions, with occupancy factors of ca 0.74 and 0.26. Secondly, all hy­droxy H atoms are further disordered, either by symmetry, or through a positional disorder in the case of parts placed in general positions. We show that the correct description of the hydrogen-bonding scheme is possible only if diffraction data are collected at low temperature. The pro­chiral character of the hydrogen-bonded tetra­meric supra­molecular clusters leads to enanti­omorphic three-dimensional graphs in each tetra­mer. The crystal is thus a racemic mixture of supS and supR motifs, consistent with the centro­symmetric nature of the Roverline{3} space group.

Crystals of the rare earth metal polytelluride LaTe1.82(1), namely, lanthanum telluride (1/1.8), have been grown by molten alkali halide flux reactions and vapour-assisted crystallization with iodine. The two-dimensionally incommensurately modulated crystal structure has been investigated by X-ray diffraction experiments. In contrast to the tetra­gonal average structure with unit-cell dimensions of a = 4.4996 (5) and c = 9.179 (1) Å at 296 (1) K, which was solved and refined in the space group P4/nmm (No. 129), the satellite reflections are not compatible with a tetra­gonal symmetry but enforce a symmetry reduction. Possible space groups have been derived by group–subgroup relationships and by consideration of previous reports on similar rare earth metal polychalcogenide structures. Two structural models in the ortho­rhom­bic superspace group, i.e. Pmmn(α,β,1 over 2)000(−α,β,1 over 2)000 (No. 59.2.51.39) and Pm21n(α,β,1 over 2)000(−α,β,1 over 2)000 (No. 31.2.51.35), with modulation wave vectors q1 = αa* + βb* + 1 over 2c* and q2 = −αa* + βb* + 1 over 2c* [α = 0.272 (1) and β = 0.314 (1)], have been established and evaluated against each other. The modulation describes the distribution of defects in the planar [Te] layer, coupled to a displacive modulation due to the formation of different Te anions. The bonding situation in the planar [Te] layer and the different Te anion species have been investigated by density functional theory (DFT) methods and an electron localizability indicator (ELI-D)-based bonding analysis on three different approximants. The temperature-dependent electrical resistance revealed a semiconducting behaviour with an estimated band gap of 0.17 eV.

The analytical solution of the problem of X-ray spherical-wave Laue diffraction in a single crystal with a linear change of thickness on the exit surface is derived. General equations are applied to a specific case of plane-wave Laue diffraction in a thick crystal under the conditions of the Borrmann effect.

Here’s what’s planned for chemical and laboratory safety at the ACS National Meeting in San Diego, which starts on Sunday. You can also take advantage of the Division of Chemical Health & Safety’s printer-friendly CHAS-At-A-Glance. Sunday, Aug. 25 Committee on Chemical Safety Open and Executive Subcommittee Meeting, 7:00–10:00 am, Marriott Marquis San Diego Marina, Marina […]

The post #Chemsafety at #ACSSanDiego appeared first on CENtral Science.

(The Paypers) Menlo Security, a global enterprise cloud security provider, has entered the Australian...