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Across species, Epidermal Growth Factor (EGF) family ligands and their receptors participate in developmental and physiological cell-cell signaling events. C. elegans possesses a single EGF receptor, LET-23/EGFR, and two characterized EGF ligands. LIN-3/EGF is well-known for its role in vulval induction, and SISS-1/EGF mediates stress-induced sleep. The C. elegans genome harbors another predicted EGF family member, igeg-2, which has not been characterized. To determine if IGEG-2 is a functional EGFR ligand, we examined whether it can activate known LET-23-dependent processes. We found that ubiquitous overexpression of IGEG-2 promotes both vulval induction and sleep, indicating that it is a functional EGF family ligand. The endogenous role of IGEG-2 remains unknown. 

Open dumping and burning of solid waste are widely practiced in underserved communities lacking access to solid waste management facilities. The generation of microplastics from these sites has been overlooked. 

The anticancer drug Gefitinib is a tyrosine kinase inhibitor with selectivity for the Epidermal Growth Factor Receptor (EGFR/ErbB1). As the C. elegans EGF receptor LET-23 shares notable structural homology over its kinase domain with human EGFR, we wished to examine whether Gefitinib treatment can interfere with LET-23-dependent processes. We show that Gefitinib disrupts C. elegans stress-induced sleep (SIS) but does not impact EGF overexpression-induced sleep nor vulva induction. These findings indicate that Gefitinib does not interfere with LET-23 signaling and impairs SIS through an off-target mechanism. 

Open dumping and burning of solid waste are widely practiced in underserved communities lacking access to solid waste management facilities; however, the generation of microplastics from these sites has been overlooked. We report elevated concentrations of microplastics (MPs) in soil of three solid waste open dump and burn sites: a single-family site in Tuttle, Oklahoma, USA, and two community-wide sites in Crow Agency and Lodge Grass, Montana, USA. We extracted, quantified, and characterized MPs from two soil depths (0-9 cm and 9-18 cm). The abundance of particles found at the three sites (35,000 to 69,200 particles kg-1 soil) equals or exceeds reported concentrations from currently understood sources of MPs including biosolids application and other agricultural practices. Attenuated total reflectance Fourier transformed infrared (ATR-FTIR) identified polyethylene as the dominant polymer across all sites (46.2%-84.8%). We also detected rayon (≤11.5%), polystyrene (up to 11.5%), polyethylene terephthalate (≤5.1), polyvinyl chloride (≤4.4%), polyester (≤3.1), and acrylic (≤2.2%). Burned MPs accounted for 76.3 to 96.9% of the MPs found in both community wide dumping sites. These results indicate that solid waste dumping and burning activities are a major source of thermally oxidized MPs for the surrounding terrestrial environment with potential to negatively affect underserved communities.