COVER Science, like the rest of society, has been swept up in the storms caused by social media. This special news section looks at how scientists study and fight mis- and disinformation, how harassment and intimidation have spiked during the COVID-19 pandemic, and how researchers use Twitter to inform the public and share their findings with colleagues. See page 1332.

Illustration: Davide Bonazzi/Salzmanart

ONLINE COVER The East River watershed in Colorado. Understanding the bedrock properties of the watershed and related feedback of environmental disturbances to groundwater can help improve downstream water management. Conventional approaches are highly localized and make it difficult to estimate on a regional scale. Uhlemann et al., applied machine learning to analyze geophysical and remote sensing data as well as near-surface geophysics of the area and created a detailed model of the East River watershed’s belowground properties. This method can help predict how regions like watersheds and coastal systems will respond to disruptions caused by climate change.

ONLINE COVER Tickling Tuft Cells with Photons. This month’s cover cover shows a pulse of blue light illuminating mouse gallbladder tissue mounted in an organ bath. Using tissue from transgenic mice expressing a light-sensitive channelrhodopsin protein in epithelial tuft cells, Keshavarz et al. found that activation of biliary tract tuft cells induced release of acetylcholine and cysteinyl leukotrienes, inflammatory mediators that elicited mucus secretion and smooth muscle contraction, respectively. A separate study by O’Leary et al. compared the transcriptomes of biliary and small intestinal tuft cells and identified bile acids as negative regulators of gallbladder tuft cell abundance.

ONLINE COVER Special Issue on Biomechanics and Exoskeleton Suits. The metabolic rate during walking can be minimized by providing assistance at the waist of individuals undergoing physical therapy. By focusing on the center of mass of an individual, the waist, Antonellis et al. develop a robotic tether system that can apply assistive forward forces with optimized magnitude and timing. The researchers show that providing assistance early in the step cycle can reduce the metabolic rate by almost half in healthy adults. This month’s cover is a photograph of an individual with the robotic tether attached to their waist while walking on a treadmill.

ONLINE COVERThis week, Caratti et al. report that, in the absence of activating ligands, the glucocorticoid receptor (GR) associates with complexes containing RAS and inhibits RAS activation. The image shows HEK293T cells expressing mCherry-tagged KRAS (red) and EGFP-tagged GR (green). Nuclei are stained blue.

ONLINE COVER Inflaming Glucose Homeostasis. The image shows a liver biopsy with advancing nonalcoholic fatty liver disease (NAFLD), including fat deposits (white) inside ballooning hepatocytes (red) surrounded by fibrosis (blue). Proinflammatory interferon regulatory factor 3 (IRF3) has been linked to NAFLD, but its mechanistic role in this setting is unclear. Examining obese mice, Patel et al. show that hepatocyte-expressed IRF3 promoted dysglycemia by inducing transcription of a serine/threonine phosphatase that in turn activated AMPK signaling. Individuals with obesity and NAFLD also displayed increased activation of hepatic IRF3 that decreased after bariatric surgery, suggesting this mechanism links obesity-induced inflammation and dysglycemia in humans.