Eric Peterman, Mindaugas Valius, and Rytis Prekeris

During mitotic cell division, the actomyosin cytoskeleton undergoes several dynamic changes that play key roles in progression through mitosis. While the regulators of cytokinetic ring formation and contraction are well-established, proteins that regulate cortical stability during anaphase and telophase have been understudied. Here, we describe a role for CLIC4 in regulating actin and actin-regulators at the cortex and cytokinetic cleavage furrow during cytokinesis. We first describe CLIC4 as a new component of the cytokinetic cleavage furrow that is required for successful completion of mitotic cell division. We also demonstrate that CLIC4 regulates the remodeling of sub-plasma membrane actomyosin network within the furrow by recruiting MST4 kinase and regulating ezrin phosphorylation. This work identifies and characterizes new molecular players involved in regulating cortex stiffness and blebbing during late stages of cytokinetic furrowing.

Samantha-Su Z. Taylor, Nicole L. Jacobsen, Tasha K. Pontifex, Paul Langlais, and Janis M. Burt

Connexin 37 (Cx37) expression profoundly suppresses proliferation of rat insulinoma (Rin) cells in a manner dependent on gap junction channel (GJCh) functionality and the presence and phosphorylation status of its carboxyl-terminus (CT). In Rin cells growth arrested by induced Cx37 expression, serine 319 (S319) is frequently phosphorylated. Preventing phosphorylation at this site (alanine substitution; S319A) relieved Cx37 of its growth suppressive effect whereas mimicking phosphorylation at this site (aspartate substitution; S319D) enhanced Cx37's growth suppressive properties. Like Cx37-WT, -S319D GJChs and hemichannels (HChs) preferred the closed state, rarely opening fully, and gated slowly. In contrast, Cx37-S319A channels preferred open states, opened fully, and gated rapidly. These data indicate that phosphorylation-dependent conformational differences in Cx37 protein and channel function underlie Cx37-induced growth arrest vs. growth permissive phenotypes. That the closed state of -WT and Cx37-S319D GJChs and HChs favors growth arrest suggests that rather than specific permeants mediating cell cycle arrest, the closed conformation instead supports interaction of Cx37 with growth regulatory proteins that result in growth arrest.

Miniature camels and horses, a rhinoceros and a giant bear-dog are among fossils unearthed in the recent excavations of the Panama Canal expansion project. These […]

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The universe is 13.8 billion years old, while our planet formed just 4.5 billion years ago. Some scientists think this time gap means that life […]

The post Is Earthly Life Premature From a Cosmic Perspective? appeared first on Smithsonian Insider.

Odile Madden knows a lot about plastic. A materials scientist with the Smithsonian Museum Conservation Institute, she has spent the past eight years studying plastics […]

The post Microplastics in our environment: A conversation with Odile Madden, Smithsonian plastics scientist appeared first on Smithsonian Insider.

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In a 24-hour-period between July 9 and 10, 2009 a clouded leopard cub, a Przewalski's horse, and a red panda cub were all born at Smithsonian's National Zoo's Conservation and Research Center in Front Royal, Virginia.

The post A clouded leopard cub, a Przewalski’s horse and a red panda cub were all recently born at the Smithsonian’s National Zoo appeared first on Smithsonian Insider.

Forensic anthropologists from the Smithsonian's National Museum of Natural History discover African remains at a Colonial burial site in Maryland. Follow them as they study the remains, reconstruct the face and body, and share what they learn about the African experience in the Chesapeake in the 1600s.

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When animal care staff at the Smithsonian's National Zoo need to know when to breed their pandas or when to expect a cub they turn to the Endocrine (Hormones) Research Lab at the Zoo's Front Royal, Va. facility.

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The post Barro Colorado Island: The Smithsonian’s research outpost in the Panama Canal appeared first on Smithsonian Insider.

Using an innovative new camera on board a sounding rocket, an international team of scientists have captured the sharpest images yet of the Sun’s outer […]

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The gates at the Smithsonian’s National Zoo re-opened to the public Friday, October 18! The live animal cams that were turned off during the government […]

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The giant panda cub at the Smithsonian’s National Zoo has started taking her first unsteady steps.

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Seven red panda cubs were born at the Smithsonian Conservation Biology Institute! The cubs were born to mothers Nutmeg, Regan and Leo Mei. Keepers are […]

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Around 6:30 a.m. on Aug. 23, 2015 veterinarians examined the cub Mei Xiang gave birth to at 5:35 p.m. Aug. 22, 2015 at the Smithsonian’s […]

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Watch a keeper train the Zoo’s clouded leopard, Tai, for voluntary cheek swabs. The DNA from these cheek swabs is used to map the genealogy […]

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Now eight months old, Giant Panda Cub Bei Bei is learning to come when called and undergoing ‘target’ training to teach him to respond to […]

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Peter Sefton, D.C. Preservation League trustee, reflects on how Washington, D.C. has changed in recent years. (Anacostia Community Museum video series)  

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The post Cool science is being carried out on a Smithsonian island in the Panama Canal appeared first on Smithsonian Insider.

The Smithsonian Tropical Research Institute (STRI) celebrated with Panama the completion of the Panama Canal expansion project on June 26, 2016. The $5.6 billion engineering […]

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Most of us can’t begin the day without a cup of coffee. Coffee is a major agricultural crop in many Central and South American countries […]

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This article aims to encourage practitioners, young and seasoned, by enhancing their structure-determination toolboxes with a selection of tips and tricks on recognizing and handling aspects of data collection, structure modelling and refinement, and the interpretation of results.

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.

In small-molecule single-crystal structure determination, we now have at our disposal an inspiring range of fantastic diffractometers with better, brighter sources, and faster, more sensitive detectors. Faster and more powerful computers provide integrated tools and software with impressive graphical user interfaces. Yet these tools can lead to the temptation not to check the work thoroughly and one can too easily overlook tell-tale signs that something might be amiss in a structure determination; validation with checkCIF is not always revealing. This article aims to encourage practitioners, young and seasoned, by enhancing their structure-determination toolboxes with a selection tips and tricks on recognizing and handling aspects that one should constantly be aware of. Topics include a pitfall when setting up data collections, the usefulness of reciprocal lattice layer images, processing twinned data, tips for disorder modelling and the use of restraints, ensuring hydrogen atoms are added to a model correctly, validation beyond checkCIF, and the derivation and interpretation of the final results.

The enanti­opure monopyrrolidine derivative (2S)-methyl (Z)-5-(2-tert-but­oxy-1-cyano-2-oxo­ethyl­idene)pyrrolidine-2-carboxyl­ate, C13H18N2O4, (1), represents a potential ligand and an attractive inter­mediate for the synthesis of chiral metal com­plexes. At the mol­ecular level, the com­pound features an intra­molecular N—H⋯O hydrogen bond; neighbouring mol­ecules inter­act via N—H⋯N contacts to form chains along [100]. Due to its elemental com­position, resonant scattering of the target com­pound is entirely insignificant for diffraction experiments with Mo Kα and small even for Cu Kα radiation. A preliminary study with the harder radiation type confirmed the chiral space group and the suitability of the single crystal chosen; as expected, the results concerning the absolute structure remained com­pletely inconclusive. A second data collection with the longer wavelength gave satisfactory quality indicators for the correct handedness of the mol­ecule, albeit with high standard uncertainties. The absolute configuration has been assessed independently: CD spectra for both enanti­omers of the target mol­ecule were calculated and the spectrum for the S-configured stereoisomer was in agreement with the experiment. The Cotton effect of (1) may be ascribed to π–π* transitions from HOMO to LUMO and from HOMO to LUMO+1. As both independent techniques agree with respect to the handedness of the target mol­ecule, the absolute structure may be assigned with a high degree of confidence.

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 Paypers) The European Banking...

Cancer-causing chemicals that occur naturally in foods are far more numerous in the human diet than synthetic carcinogens, yet both types are consumed at levels so low that they currently appear to pose little threat to human health, a committee of the National Research Council said in a report released today.

Good morning. I am Richard Bonnie, chair of the Committee on Developing a Strategy to Reduce and Prevent Underage Drinking.

In 1916, the National Academy of Sciences established the National Research Council.

A systemwide change to the culture and climate in higher education is needed to prevent and effectively respond to sexual harassment, says a new report from the National Academies of Sciences, Engineering, and Medicine.

Black lung disease cases in coal miners have been increasing since 2000 for uncertain reasons.

A new report from the National Academies of Sciences, Engineering, and Medicine highlights the dynamic process of learning throughout the life span and identifies frontiers in which more research is needed to pursue an even deeper understanding of human learning.

On the 10th Anniversary of the Deepwater Horizon Explosion, Marcia McNutt Reflects on How Science Helped Solve the Crisis, and Its Lessons for the COVID-19 Pandemic