The formation and properties of liquid-ordered (Lo) lipid domains (rafts) in the plasma membrane are still poorly understood. This limits our ability to manipulate ordered lipid domain-dependent biological functions. Giant plasma membrane vesicles (GPMVs) undergo large-scale phase separations into coexisting Lo and liquid-disordered lipid domains. However, large-scale phase separation in GPMVs detected by light microscopy is observed only at low temperatures. Comparing Förster resonance energy transfer-detected versus light microscopy-detected domain formation, we found that nanodomains, domains of nanometer size, persist at temperatures up to 20°C higher than large-scale phases, up to physiologic temperature. The persistence of nanodomains at higher temperatures is consistent with previously reported theoretical calculations. To investigate the sensitivity of nanodomains to lipid composition, GPMVs were prepared from mammalian cells in which sterol, phospholipid, or sphingolipid composition in the plasma membrane outer leaflet had been altered by cyclodextrin-catalyzed lipid exchange. Lipid substitutions that stabilize or destabilize ordered domain formation in artificial lipid vesicles had a similar effect on the thermal stability of nanodomains and large-scale phase separation in GPMVs, with nanodomains persisting at higher temperatures than large-scale phases for a wide range of lipid compositions. This indicates that it is likely that plasma membrane nanodomains can form under physiologic conditions more readily than large-scale phase separation. We also conclude that membrane lipid substitutions carried out in intact cells are able to modulate the propensity of plasma membranes to form ordered domains. This implies lipid substitutions can be used to alter biological processes dependent upon ordered domains.

pncRNA-D is an irradiation-induced 602-nt long noncoding RNA transcribed from the promoter region of the cyclin D1 (CCND1) gene. CCND1 expression is predicted to be inhibited through an interplay between pncRNA-D and RNA-binding protein TLS/FUS. Because the pncRNA-D–TLS interaction is essential for pncRNA-D–stimulated CCND1 inhibition, here we studied the possible role of RNA modification in this interaction in HeLa cells. We found that osmotic stress induces pncRNA-D by recruiting RNA polymerase II to its promoter. pncRNA-D was highly m6A-methylated in control cells, but osmotic stress reduced the methylation and also arginine methylation of TLS in the nucleus. Knockdown of the m6A modification enzyme methyltransferase-like 3 (METTL3) prolonged the half-life of pncRNA-D, and among the known m6A recognition proteins, YTH domain-containing 1 (YTHDC1) was responsible for binding m6A of pncRNA-D. Knockdown of METTL3 or YTHDC1 also enhanced the interaction of pncRNA-D with TLS, and results from RNA pulldown assays implicated YTHDC1 in the inhibitory effect on the TLS–pncRNA-D interaction. CRISPR/Cas9-mediated deletion of candidate m6A site decreased the m6A level in pncRNA-D and altered its interaction with the RNA-binding proteins. Of note, a reduction in the m6A modification arrested the cell cycle at the G0/G1 phase, and pncRNA-D knockdown partially reversed this arrest. Moreover, pncRNA-D induction in HeLa cells significantly suppressed cell growth. Collectively, these findings suggest that m6A modification of the long noncoding RNA pncRNA-D plays a role in the regulation of CCND1 gene expression and cell cycle progression.

ssm euromicron GmbH, a system house subsidiary of euromicron AG, is involved in a project to provide the technical equipment for the new building for the Institute of Geosciences at Kiel’s Christian Albrechts University. The seven-story new building is part of a campus-wide modernization initiative that is one of the largest public high-rise projects in the federal state of Schleswig-Holstein.

A new study from University of Michigan climate researchers concludes that some of the latest-generation climate models may be overly sensitive to carbon dioxide increases and therefore project future warming that is unrealistically high.

To imagine earth without greenhouse gases in its atmosphere is to turn the familiar blue marble into a barren lump of rock and ice on which the average surface temperature hovers around -18ºC. Such a planet would not receive less of the sunlight which is the ultimate source of all Earth's warmth. But when the energy it absorbed from the sunlight was re-emitted as infrared radiation, as the laws of physics require, it would head unimpeded back out into space.

Pietro Mercuri and René Schoof
Math. Comp. 89 (2020), 1969-1991.
Abstract, references and article information

A lone developer from the company that provided aerodynamic analysis for the cars in the PlayStation game Gran Turismo has applied the tooling to demonstrate the spread of germs with and without wearing a mask

Galatia Cleanthous and Athanasios G. Georgiadis
Trans. Amer. Math. Soc. 373 (2020), 3323-3356.
Abstract, references and article information

N. O. Malykh and I. S. Postevoy
Theor. Probability and Math. Statist. 99 (2020), 189-198.
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S. S. Lohvinenko and K. V. Ralchenko
Theor. Probability and Math. Statist. 99 (2020), 149-168.
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A. G. Kukush and O. O. Chernova
Theor. Probability and Math. Statist. 99 (2020), 125-135.
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Yu. V. Kozachenko and I. V. Rozora
Theor. Probability and Math. Statist. 99 (2020), 113-124.
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A. V. Ivanov and I. K. Matsak
Theor. Probability and Math. Statist. 99 (2020), 91-99.
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O. D. Borysenko and D. O. Borysenko
Theor. Probability and Math. Statist. 99 (2020), 67-75.
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S. V. Bodnarchuk and O. M. Kulyk
Theor. Probability and Math. Statist. 99 (2020), 53-65.
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Bin Li and Jieqiong Shen
Proc. Amer. Math. Soc. 148 (2020), 2565-2578.
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Naoya Hiramatsu and Ryo Takahashi
Proc. Amer. Math. Soc. 148 (2020), 2359-2369.
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Below, Mac Hyman, Tulane University, talks about types of mathematical models--their strengths and weaknesses--the data that we currently have and what we really need, and what models can tell us about a possible second wave.

At the beginning of the video, he thanks the mathematics community for its work, and near the end says, "Our mathematical community is really playing a central role in helping to predict the spread, and help mitigate this epidemic, and prioritize our efforts. …Do not underestimate the power that mathematics can have in helping to mitigate this epidemic—-we have a role to play."

See the full set of videos on modeling COVID-19 and see media coverage of mathematics' role in modeling the pandemic.