Scientists examining the stomach contents of invasive lionfish caught on the inner barrier reef of Belize have discovered that nearly half of the diet of […]

The post In Belize, Critically endangered wrasse now favorite food of invasive lionfish appeared first on Smithsonian Insider.

Studies show that on average, the weight of cremated remains for men is about 7.13 pounds (plus or minus 1.2 pounds) and for women, 4.9 […]

The post Hi-Tech Analysis Cracks Curious Case of Contaminated Cremains appeared first on Smithsonian Insider.

The world’s coasts are home to more than 70 percent of the human population and experience intense development as a result. The rate of environmental […]

The post Smithsonian Environmental Research Center Marks 50 Years of Making a Difference appeared first on Smithsonian Insider.

The Inka Empire is one of the greatest civilizations in the Western Hemisphere, spanning from the 13th century until the Spanish invasion in 1532. To […]

The post 5 Reasons the Inka Road is one of the Greatest Achievements in Engineering appeared first on Smithsonian Insider.

Geologic mapping is an integral part of exploration and understanding a planetary landscape, because it shows the relationships between geologic units and helps delineate the […]

The post Geologic Mapping of Mars appeared first on Smithsonian Insider.

For the first time, researchers at the Smithsonian Conservation Biology Institute’s Migratory Bird Center have accurately tracked small migratory ovenbirds (Seiurus aurocapilla) to their tropical […]

The post Miniaturized GPS Tags Allow Tracking of Small Songbirds for first time appeared first on Smithsonian Insider.

Tiny Anolis lizards preserved since the Miocene in amber are giving scientists a true appreciation of the meaning of community stability. Dating back some 15 […]

The post Trapped in Amber: Ancient fossils reveal remarkable stability of Caribbean lizard communities appeared first on Smithsonian Insider.

Warming temperatures may mean more generations of monarch butterflies in North America during summer months, say scientists who recently finished experiments with monarch caterpillars and […]

The post Warming temperatures may mean more monarch generations in some areas of North America appeared first on Smithsonian Insider.

We only have one example of a planet with life: Earth. But within the next generation, it should become possible to detect signs of life […]

The post Interstellar Seeds Could Create Oases of Life appeared first on Smithsonian Insider.

Recently crowned the “astronomy photo of the year” by Slate’s Bad Astronomy blog, a new image of a region of Orion’s belt reveals the deepest […]

The post Stunning deep space photo reveals new details of Orion nebulae appeared first on Smithsonian Insider.

Smithsonian scientists and colleagues have discovered a new genus and species of river dolphin that has long been extinct. They made the discovery after carefully […]

The post Fossil Specimen Reveals a New Species of Ancient River Dolphin appeared first on Smithsonian Insider.

The Mojave Desert and Death Valley are among the hottest, driest places in North America. So how might climate change impact a resilient reptile that […]

The post Warming may shrink ancient range of heat loving desert lizard appeared first on Smithsonian Insider.

DNA analysis is proving to be a valuable tool for scientists trying to gauge the environmental impact that invasive blue catfish (Ictalurus furcatus) and flathead […]

The post DNA solves puzzle of catfish dinners appeared first on Smithsonian Insider.

A word to the wise: don’t ask a paleontologist to pick a favorite fossil. It’s like asking your mother which child she loves most, or […]

The post Fossils help scientists build a picture of the past—and present appeared first on Smithsonian Insider.

Researchers have uncovered a fossil sea urchin that pushes back a fork in its family tree by 10 million years, according to a new study. […]

The post Newly discovered sea urchin fossil is oldest of its kind appeared first on Smithsonian Insider.

The collection of rocky planets orbiting distant stars has just grown by one, and the latest discovery is the most intriguing one to date. The […]

The post Astronomers Eager to Get a Whiff of Newfound Venus-like Planet appeared first on Smithsonian Insider.

In many ways stars are like living beings. They’re born; they live; they die. And they even have a heartbeat. Using a novel technique, astronomers […]

The post DISCOVERY MEASURES “HEARTBEATS” OF A DISTANT GALAXY’S STARS appeared first on Smithsonian Insider.

Tucked away on the lower levels of the Smithsonian’s National Museum of Natural History and National Museum of American History are some of science’s most […]

The post Smithsonian Libraries’ rare texts include early superstars of science appeared first on Smithsonian Insider.

Stealthy. Aggressive. Lethal. Assassin flies are predators that hunt and feed on other insects. They are the third most diverse group of flies, with more […]

The post Killer Insect profile: The Assassin Fly appeared first on Smithsonian Insider.

A Smithsonian team of scientists re-examined a fossil sperm whale for the first time in 90 years and created an entirely new group in the […]

The post “Call Me Albicetus”: Fossil Sperm Whale Is Named in Honor of Moby-Dick appeared first on Smithsonian Insider.

Many animals change sex at some point in their lives, often after reaching a certain size. Snails called slipper limpets begin life as males, and […]

The post The Power of Touch: Sex-changing snails switch sooner when together appeared first on Smithsonian Insider.

Scientists at the Smithsonian Institution and partners have published a paper that will help them save Panamanian frog species from extinction due to a deadly […]

The post New Study Helps Smithsonian Scientists Prioritize Frogs at Risk of Extinction appeared first on Smithsonian Insider.

How did the universe begin? And what came before the Big Bang? Cosmologists have asked these questions ever since discovering that our universe is expanding. […]

The post Theorists Propose a New Method to Probe the Beginning of the Universe appeared first on Smithsonian Insider.

For the past 50 years, the number of wood thrush (Hylocichla mustelina) that breed in the United States has decreased more than 60 percent. However, […]

The post Smithsonian Scientists Solve Puzzle of Dramatic Wood Thrush Decline appeared first on Smithsonian Insider.

It is rare but not entirely uncommon to see a manatee swimming in the Atlantic waters of Maryland and Virginia. This one was dead, however, […]

The post In face of mass extinctions, Smithsonian’s Global Genome Initiative quietly saves world’s DNA appeared first on Smithsonian Insider.

Ten years ago, cownose rays in the Atlantic got a bad rap when this species (Rhinoptera bonasus) was accused of excessively eating up scallops in […]

The post Cownose Rays Aquitted: Not Guilty of Decimating Chesapeake Oysters appeared first on Smithsonian Insider.

Because there is no polite way to ask a mite to sit still for its portrait, Gary Bauchan often gives his tiny subjects a shot […]

The post Enjoy Face Time with Seven of Earth’s 3-5 Million Mite Species appeared first on Smithsonian Insider.

When soil temperatures 8 inches under the ground reach a balmy 64 degrees Fahrenheit, periodical cicadas emerge on the U.S. East Coast. They tend to […]

The post Billions & Billions of Periodical Cicadas appeared first on Smithsonian Insider.

The planet’s last stronghold of wild cheetahs (Acinonyx jubatus) is losing genetic diversity at an alarming rate according to a new study from the Smithsonian […]

The post Smithsonian Study reveals Decline of Genetic Diversity in Wild Cheetahs 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.

Thirty years after the scimitar-horned oyrx were driven to extinction, the desert antelope will return to the last-known place it existed: Chad’s Sahelian grasslands. The […]

The post Extinct-in-the-Wild Antelope Return to the Grasslands of Chad appeared first on Smithsonian Insider.

(Study is one of dozens to be presented by bird scientists this week at the 2016 North American Ornithological Conference in Washington, D.C.) To catch tuna […]

The post Fishing gear entanglements of marine birds is focus of Smithsonian ecologist’s study appeared first on Smithsonian Insider.

A fossil that has been in the collection of the Smithsonian’s National Museum of Natural History since it was discovered in 1951 is today helping […]

The post New Species of Extinct River Dolphin Discovered in Smithsonian Collection appeared first on Smithsonian Insider.

According to a new study, eating sea turtle eggs increases the health risk of heavy metal exposure in local communities in Panama and may provide […]

The post Human health risks of eating sea turtle eggs could benefit species appeared first on Smithsonian Insider.

Crustaceans that thrive in the vastness of the open ocean have no place to hide from their predators. Consequently, many creatures that live at depths […]

The post Tiny ocean crustaceans wear invisibility cloak of living bacteria appeared first on Smithsonian Insider.

With roughly 5,500 individuals remaining in the wild, the black rhino population is critically endangered. To help save these iconic African giants, at risk for […]

The post A Planet in Peril: Q&A with Suzan Murray of the Smithsonian Global Health Program appeared first on Smithsonian Insider.

To fully know a species and develop sound conservation efforts, its full life cycle must be understood. But tracking small migratory birds for thousands of […]

The post Keeping Track of Kirtland’s Warbler All Year Long―A Scientific First appeared first on Smithsonian Insider.

Firm though it was, Kaitlyn Wilson’s gentle grip on the rust-brown female cardinal didn’t stop the bird from twisting its head around to deliver a […]

The post Urban Nestwatch: A bird in hand awakens a lifetime of wildlife awareness appeared first on Smithsonian Insider.

With its homely featherless head, undertaker’s charcoal coloring and association with death and decay, the turkey vulture (Cathartes aura) tops few lists as a favorite […]

The post Scientists in awe of huge olfactory bulb found in turkey vulture brain 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.

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.

Flitting swiftly through the darkness above the tropical forest canopy in Central and South America, a group of cute little bats with dog-like faces have […]

The post More sky puppies! Scientists discover two new species of dog-faced bat 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.

In the early 20th century, Canada geese were considered endangered in the U.S. So in the 1950s and 1960s, birds from the Midwest were released […]

The post Study of bacteria inside guts of wild Canada geese shows greater danger than earlier studies exposed appeared first on Smithsonian Insider.

Ninety Limosa harlequin frogs (Atelopus limosus) bred in human care are braving the elements of the wild after Smithsonian scientists sent them out into the […]

The post Panama: First release of endangered frogs appeared first on Smithsonian Insider.

l-Hydroxyproline (l-Hyp) is a nonstandard amino acid that is present in certain proteins, in some antibiotics and in the cell-wall components of plants. l-Hyp is the product of the post-translational modification of protein prolines by prolyl hydroxylase enzymes, and the isomers trans-3-hydroxy-l-proline (T3LHyp) and trans-4-hydroxy-l-proline (T4LHyp) are major components of mammalian collagen. T4LHyp follows two distinct degradation pathways in bacteria and mammals, while T3LHyp is metabolized by a two-step metabolic pathway that is conserved in bacteria and mammals, which involves a T3LHyp dehydratase and a Δ1-pyrroline-2-carboxylate (Pyr2C) reductase. In order to shed light on the structure and catalysis of the enzyme involved in the second step of the T3LHyp degradation pathway, the crystal structure of Pyr2C reductase from the archaeon Thermococcus litoralis DSM 5473 complexed with NADH and l-proline is presented. The model allows the mapping of the residues involved in cofactor and product binding and represents a valid model for rationalizing the catalysis of Pyr2C reductases.

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.