COVER Artist's rendering of the path from a positive COVID-19 test to a potential drug treatment. Researchers have developed a drug to target SARS-CoV-2, the virus that causes COVID-19. The molecule, known as PF-07321332, blocks the virus’s main protease, an enzyme critical to its replication. The molecule can be delivered in pill form, which may lead to a COVID-19 treatment that can be used outside of a hospital setting. See page 1586.

Illustration: Jason Solo/The Jacky Winter Group

ONLINE COVER Endoggresomes, which are toxic to nerve cells, form within nerve fibers. These swellings are common features of neurodegenerative diseases, including rare, inherited forms of prion diseases—disorders that cause rapidly developing dementia, severe disability, and death. Chassefeyre et al. identified the toxic pathway of endoggresomes as it forms along microtubules and moves into the axon. The research could lead to targeted therapeutic strategies to reduce the formation of toxic endoggresomes and, in turn, to prevent neuronal dysfunction.

ONLINE COVER Inflammatory SINEs. This month's cover features a retinal color photograph showing age-related macular degeneration in a 75-year-old man. In the center of the retina, damage to the retinal pigment epithelium (RPE) has caused enhanced visibility of the underlying choroidal blood vessels and impaired vision. Wang et al. identified DDX17, an RNA helicase, as a sensor of elevated levels of RNA transcripts from short interspersed nuclear elements (SINEs). DDX17 can initiate a noncanonical form of NLRC4-mediated inflammasome activation leading to RPE degeneration in the eye.

ONLINE COVER Takeoff and Landings. The ability for aerial robots to take off and land on a variety of irregular surfaces will broaden the range of environments where these robots could be deployed. Influenced by how birds take off, land, and grasp, Roderick et al. have developed a bird-inspired grasping system called Stereotyped Nature-inspired Aerial Grasper (SNAG). The researchers integrated SNAG into a quadcopter to demonstrate perching on tree branches of different sizes, orientations, and surface conditions. This month's cover is a photograph of SNAG on a quadcopter perched on a branch.

ONLINE COVER This week, Yim et al. used mass spectrometry to identify the Gβ and Gγ subunits that interact with the SNARE complex, which mediates vesicle exocytosis, in synaptosomes from mouse brain. The image is a color-enhanced electron micrograph of a cell exhibiting exocytosis.

ONLINE COVER Schistosomiasis Drug Target Solved. This image depicts an adult Schistosoma mansoni parasite, the causative agent of schistosomiasis. For decades, praziquantel (PZQ) has been the drug of choice to treat schistosomiasis, but its mechanism was not known. In a pair of manuscripts, Park et al. and Le Clec'h et al. identified transient receptor potential melastatin ion channel (TRPM_PZQ) as the target of PZQ using ligand-based screening and targeted mutagenesis, as well as a genome-wide association screen. They confirmed that TRPM_PZQ is broadly conserved in parasites and provide critical information for monitoring PZQ resistance in field isolates.