The crystal structures of 5-bromo-1,3-di-tert-butyl-2-[(tri­methyl­sil­yl)­oxy]benzene, C17H29BrOSi, (I), 1,3-di-tert-butyl-2-[(tri­methyl­sil­yl)­oxy]benzene, C17H30OSi, (II), and N-(2,6-diiso­propyl­phen­yl)-1,1,1-trimethyl-N-(tri­methyl­sil­yl)silanamine, C18H35NSi2, (III), are reported. Compound (I) crystallizes in space group P21/c with Z' = 1, (II) in Pnma with Z' = 0.5 and (III) in Cmcm with Z' = 0.25. Consequently, the mol­ecules of (II) are constrained by m and those of (III) by m2m site symmetries. Despite this, both (I) and (II) are distorted towards mild boat conformations, as is typical of 2,6-di-tert-butyl-substituted phenyl compounds, reflecting the high local steric pressure of the flanking alkyl groups. Compound (III) by contrast is planar and symmetric, and this lack of distortion is compatible with the lower steric pressure of the flanking 2,6-diisopropyl substituents.

The crystal structures of tris­[9,9-dihexyl-2-(5-meth­oxy­pyridin-2-yl-κN)-9H-fluoren-3-yl-κC3]iridium pentane monosolvate, [Ir(C31H38NO)3]·C5H12, (I), di-μ2-chlorido-bis­{bis­[2-(5-fluoro­pyridin-2-yl)-9,9-dihexyl-9H-fluoren-3-yl]iridium} pentane 0.3-solvate, [Ir2(C30H35FN)4Cl2]·0.3C5H12, (II), di-μ2-cyanato-bis­{bis­[9,9-dihexyl-2-(5-meth­oxy­pyridin-2-yl)-9H-fluoren-1-yl]iridium} pentane monosolvate, [Ir2(C31H38NO)4(NCO)2(NCO)2]·C5H12, (III), and {μ-N,N'-bis­[3,5-bis­(tri­fluoro­meth­yl)phen­yl]oxamidato}bis(bis{2-[4-(2,4,6-trimethylphenyl)pyridin-2-yl]phenyl-κ2C1,N'}iridium)–chloro­benzene–pentane (1/2.3/0.4), [Ir2(C20H19N)4(C18H6F12N2O2)]·2.3C6H5Cl·0.4C5H12, (IV), synthesized in the quest for organic light-emitting devices, were determined. The bis-μ2-chloro and bis-μ2-cyanato complexes have ΔΔ and ΛΛ configurations of the distorted octa­hedral Ir centres in racemic crystals, whereas the oxamido complex has a centrosymmetric (meso) structure with the ΔΛ configuration. The bridging oxamido moiety has a nearly planar anti geometry. All structures show substantial disorder of both host mol­ecules and solvents of crystallization.

Water is a critical molecule for human life, and, because it is abundant in space, it also plays an important role in the life of […]

The post Astronomers appraise the amount of water in the Orion Nebula appeared first on Smithsonian Insider.

In an event that has astronomers mystified; the famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any flare previously seen from the object.

The post Recent eruptions in the Crab Nebula mystify astronomers appeared first on Smithsonian Insider.

A local supernova factory has recently started production, according to a wealth of new data from NASA's Chandra X-ray Observatory on the Carina Nebula.

The post The Carina Nebula, a local supernova factory, is ramping up production appeared first on Smithsonian Insider.

To celebrate its 22nd anniversary in orbit, the Hubble Space Telescope has released a dramatic new image of the star-forming region 30 Doradus, also known […]

The post New image of the star-forming region 30 Doradus, also known as the Tarantula Nebula appeared first on Smithsonian Insider.

Most skygazers recognize the Orion Nebula, one of the closest stellar nurseries to Earth. Although it makes for great views in backyard telescopes, the Orion […]

The post Cat’s Paw Nebula “littered” w/ baby stars 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.

Globular star clusters are extraordinary in almost every way. They’re densely packed, holding a million stars in a ball only about 100 light-years across on […]

The post Globular Clusters Could Nurture Interstellar Civilizations 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.

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.

Laura O'Regan, Giancarlo Barone, Rozita Adib, Chang Gok Woo, Hui Jeong Jeong, Emily L. Richardson, Mark W. Richards, Patricia A.J. Muller, Spencer J. Collis, Dean A. Fennell, Jene Choi, Richard Bayliss, and Andrew M. Fry

EML4-ALK is an oncogenic fusion present in ~5% non-small cell lung cancers. However, alternative breakpoints in the EML4 gene lead to distinct variants with different patient outcomes. Here, we show in cell models that EML4-ALK variant 3 (V3), which is linked to accelerated metastatic spread, causes microtubule stabilization, formation of extended cytoplasmic protrusions and increased cell migration. It also recruits the NEK9 and NEK7 kinase to microtubules via the N-terminal EML4 microtubule-binding region. Overexpression of wild-type EML4 as well as constitutive activation of NEK9 also perturb cell morphology and accelerate migration in a microtubule-dependent manner that requires the downstream kinase NEK7 but not ALK activity. Strikingly, elevated NEK9 expression is associated with reduced progression-free survival in EML4-ALK patients. Hence, we propose that EML4-ALK V3 promotes microtubule stabilization through NEK9 and NEK7 leading to increased cell migration. This represents a novel actionable pathway that could drive metastatic disease progression in EML4-ALK lung cancer.

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.

David Guerit, Pauline Marie, Anne Morel, Justine Maurin, Christel Verollet, Brigitte Raynaud-Messina, Serge Urbach, and Anne Blangy

Among hematopoietic cells, osteoclasts (Oc) and immature dendritic cells (Dc) are closely related myeloid cells with distinct functions; Oc participate skeleton maintenance while Dc sample the environment for foreign antigens. Such specificities rely on profound modifications of gene and protein expression during Oc and Dc differentiation. We provide global proteomic and transcriptomic analyses of primary mouse Oc and Dc, based on original SILAC and RNAseq data. We established specific signatures for Oc and Dc including genes and proteins of unknown functions. In particular, we showed that Oc and Dc have the same α and β tubulin isotypes repertoire but that Oc express much more β tubulin isotype Tubb6. In both mouse and human Oc, we demonstrate that elevated expression of Tubb6 in Oc is necessary for correct podosomes organization and thus for the structure of the sealing zone, which sustains the bone resorption apparatus. Hence, lowering Tubb6 expression hindered Oc resorption activity. Overall, we highlight here potential new regulators of Oc and Dc biology and illustrate the functional importance of the tubulin isotype repertoire in the biology of differentiated cells.

Laurence Haren, Dorian Farache, Laurent Emorine, and Andreas Merdes

-tubulin is a major protein involved in the nucleation of microtubules in all eukaryotes. It forms two different complexes with proteins of the GCP family (gamma-tubulin complex proteins): -tubulin small complexes (TuSCs), containing -tubulin and GCPs 2 and 3, and -tubulin ring complexes (TuRCs), containing multiple TuSCs, in addition to GCPs 4, 5, and 6. Whereas the structure and assembly properties of TuSCs have been intensively studied, little is known about the assembly of TuRCs, and about the specific roles of GCPs 4, 5, and 6. Here, we demonstrate that two copies of GCP4 and one copy each of GCP5 and GCP6 form a salt-resistant sub-complex within the TuRC that assembles independently of the presence of TuSCs. Incubation of this sub-complex with cytoplasmic extracts containing TuSCs leads to the reconstitution of TuRCs that are competent to nucleate microtubules. In addition, we investigate sequence extensions and insertions that are specifically found at the amino-terminus of GCP6, and between the GCP6 grip1 and grip2 motifs, and we demonstrate that these are involved in the assembly or stabilization of the TuRC.

Ana Loncar, Sergio A. Rincon, Manuel Lera Ramirez, Anne Paoletti, and Phong T. Tran

To segregate the chromosomes faithfully during cell division, cells assemble a spindle that captures the kinetochores and pulls them towards opposite poles. Proper spindle function requires correct interplay between microtubule motors and non-motor proteins. Defects in spindle assembly or changes in spindle dynamics are associated with diseases like cancer or developmental disorders. Here we compared mitotic and meiotic spindles in fission yeast. We show that even though mitotic and meiotic spindles undergo the typical three phases of spindle elongation, they have distinct features. We found that the relative concentration of kinesin-14 Pkl1 is decreased in meiosis I compared to mitosis, while the concentration of kinesin-5 Cut7 remains constant. We identified the second kinesin-14 Klp2 and microtubule dynamics as factors necessary for proper meiotic spindle assembly. This work defines differences between mitotic and meiotic spindles in fission yeast, and provides prospect for future comparative studies.

The Crab Nebula is one of the most studied objects in the night sky. First observed by Chinese astronomers in 1054 A.D., and possibly others, this supernova remnant and its neutron star have become favorite targets for amateur and professional astronomers alike. The Chandra X-Ray Observatory is operated for NASA by the Smithsonian Astrophysical Observatory in Cambridge, Mass.

The post Chandra X-Ray Observatory podcast: The crab nebula appeared first on Smithsonian Insider.

The post After a bulldozer unearthed five statues in Ain Ghazal, Jordan in 1984, Smithsonian conservators carefully restore these otherworldy figures appeared first on Smithsonian Insider.

Smithsonian scientists and colleagues, however, have recently found evidence that gymnosperm plants shared an intricate pollination relationship with scorpionfly insects 62 million years before flowering plants appear in fossil records.

The post Prehistoric pollination: Scorpionfly mouthparts fit tubular channels of gymnosperm cones appeared first on Smithsonian Insider.

Vaishnavi Ananthanarayanan
Apr 17, 2020; 133:jcs245928-jcs245928
Meeting Report

Bullying is a serious public health problem, with significant short- and long-term psychological consequences for both the targets and perpetrators of such behavior, and requires a commitment to developing preventive and interventional policies and practices that could make a tangible difference in the lives of many children, says a new report from the National Academies of Sciences, Engineering, and Medicine.

Terry Donahue and Pat Henschel in "A Secret Love"; Credit: Netflix/A Secret Love (2020)

Larry Mantle and KPCC film critics Lael Loewenstein and Tim Cogshell review this weekend’s new movie releases on streaming and on demand platforms.

• "Bull" on VOD (iTunes & FandangoNOW)

• "A Secret Love" on Netflix

• "Deerskin" on virtual cinemas, including Laemmle's & The Frida Cinema

• "The Wretched" on VOD (iTunes & Google Play)

• "The Half Of It" on Netflix

• "All Day And A Night" on Netflix 

• "Vanilla" on VOD (Vudu, Google Play & iTunes)

• "South Mountain" on VOD/DVD (iTunes, Amazon, Google Play & Vudu)

• "Working Man" on VOD (iTunes, Google Play, FandangoNOW & Vudu) 

Our FilmWeek critics have been curating personal lists of their favorite TV shows and movies to binge-watch during self-quarantine. You can see recommendations from each of the critics and where you can watch them here.

Guests:

Lael Loewenstein, KPCC film critic and film columnist for the Santa Monica Daily Press; she tweets @LAELLO

Tim Cogshell, film critic for KPCC, Alt-Film Guide and CineGods.com; he tweets @CinemaInMind

This content is from Southern California Public Radio. View the original story at SCPR.org.

With the supply/demand balance moving in favor of miners, the outlook for uranium stocks is the brightest it has been in years, according to McAlinden Research Partners.

With the supply/demand balance moving in favor of miners, the outlook for uranium stocks is the brightest it has been in years, according to McAlinden Research Partners.

You’ve probably heard the term “flattening the curve” more times than you can count over the past couple of weeks. But if we’re being totally honest with each other, there’s a good chance there’s something else that needs flattening, too.

Americans will profess their love this Valentine's Day by digging deeper into their wallets than ever before, new research shows.

This image from the National Optical Astronomy Observatory may look like a space flower, but it's actually a planetary nebula.

New research from the University of Kansas finds that ride-booking apps have helped to free up ambulances.

Burger King released an eye-opening anti-bullying ad by seeing how their own customers responded to bullied kids vs. a bullied burger.

Looking for a side dish for your Easter dinner that's out of the norm? These delicious cakes would do the trick - just don't tell your guests they're eating bir

The gorgeously illustrated "Prefabulous World" highlights some of the most cutting-edge, eco-friendly modular homes in the world.

Scientists estimate more than 7,000 dangerous methane 'bumps' have formed in Siberia's Yamal and Gydan peninsulas over the last couple of years.

The idea behind Toshiko Horiuchi MacAdam's lovely, loopy play structures was born when children started playing on the designer's crochet sculpture in an art ga

Bulldog rides zipline to Costa Rican treehouse home

The basic organizing concept is flexible and creative yet specific enough to work for most people.

If you love the idea of long-lasting LED bulbs but not the price, this one-day Amazon Gold Box Deal may put these energy savers in your price range.

And it's potentially more efficient than an LED.

RGB-type LED bulbs like the Philips Hue give you a lot of control and they're a lot of fun, too.

ArmorLites are CFL bulbs with a special 'skin' that prevents mercury exposure if the bulb is broken. But is mercury exposure even something to worry about?

Antique bulbs create retro vibe but also are the most-energy guzzling option for restaurants.

Goat farmers 'The Fabulous Beekman Boys' take million dollar prize on 'The Amazing Race' after a rocky season.

A joint scientific statement reveals that the use of sugar-free products doesn't necessarily guarantee a smaller waistline.

A tour of the Bullitt Center in Seattle confirms that it's as green as it can be.

Despite inherent flaws, House in the Tree is a fanciful fir-based escape.

Sorry to see 100-watt bulbs disappear from stores because they were energy hogs? LED bulbs will roughly match the 100-watters for size and brightness, but their

Although several manufacturers have plans to release long-lasting, energy-sipping LED A-Line bulbs that replace the near-obsolete 100-watt incandescent, Osram S

Firm in the belief that light should help you <i>live</i> in addition to see, two young eco-entrepreneurs have created a family of super-brainy, Bluetooth-enabl

For those who prefer their meteorological forecasts to be startlingly literal, check out this WiFi-enabled chandelier that magically produces indoor clou