T o date, hundreds of thousands of deaths have been attributed to coronavirus disease 2019 (COVID-19) 1. Millions of infections by SARS-CoV-2, the virus responsible for COVID-19, have been reported, although its full extent has yet to be determined owing to limited testing 2. Government interventions to slow viral spread have disrupted daily life and economic activity for billions of people. Strategies to ease restraints on human mobility and interaction without provoking a major resurgence of transmission and mortality will depend on accurate estimates of population levels of infection and immunity 3. Current testing for the virus largely depends on labor-intensive molecular techniques 4. Individuals with positive molecular tests represent only a small fraction of all infections, given limited deployment and the brief time window when real-time (RT)-PCR testing has the highest sensitivity 5-7. The proportion of undocumented cases in the original epidemic focus was estimated to be as high as 86% 8 , and asymptomatic infections are suspected to play a substantial role in transmission 9-14. Widely available, reliable antibody detection assays would enable more accurate estimates of SARS-CoV-2 prevalence and incidence. On February 4, 2020, the Secretary of the US Department of Health and Human Services issued an emergency use authorization (EUA) for the diagnosis of SARS-CoV-2 15 , allowing nucleic acid detection and immunoassay tests to be offered based on manufacturer-reported data without formal US Food and Drug Administration (FDA) clearance 16. In response, dozens of companies began to market laboratory-based immunoassays and point-of-care (POC) tests. Rigorous, comparative performance data are crucial to inform clinical care and public health responses.

Chimeric genes, which form through the genomic fusion of two protein-coding genes, are a significant source of evolutionary novelty in Drosophila melanogaster. However, the propensity of chimeric genes to produce adaptive phenotypic changes is not fully understood. Here, we describe the chimeric gene Quetzalcoatl (Qtzl; CG31864), which formed in the recent past and swept to fixation in D. melanogaster. Qtzl arose through a duplication on chromosome 2L that united a portion of the mitochondrially targeted peptide CG12264 with a segment of the polycomb gene escl. The 3′ segment of the gene, which is derived from escl, is inherited out of frame, producing a unique peptide sequence. Nucleotide diversity is drastically reduced and site frequency spectra are significantly skewed surrounding the duplicated region, a finding consistent with a selective sweep on the duplicate region containing Qtzl. Qtzl has an expression profile that largely resembles that of escl, with expression in early pupae, adult females, and male testes. However, expression patterns appear to have been decoupled from both parental genes during later embryonic development and in head tissues of adult males, indicating that Qtzl has developed a distinct regulatory profile through the rearrangement of different 5′ and 3′ regulatory domains. Furthermore, misexpression of Qtzl suppresses defects in the formation of the neuromuscular junction in larvae, demonstrating that Qtzl can produce phenotypic effects in cells. Together, these results show that chimeric genes can produce structural and regulatory changes in a single mutational step and may be a major factor in adaptive evolution.adaptation | new genes | regulatory evolution | frameshifts C himeric genes form when complex genetic changes fuse portions of existing genes to produce a novel ORF. Such rearrangements can produce novel combinations of existing modular elements, contributing to the development of genes with novel functions (1). Chimeric genes appear to be common in the genomes of multicellular organisms, including humans (2-5). They are formed often in Drosophila melanogaster (5, 6), and there are several known examples of chimeric genes that have been stably incorporated into the genome (5). Although a handful of chimeric genes shows signatures of positive selection in Drosophila (7-12), there are very few with known functions, and the factors influencing the physiological and evolutionary impacts of chimeric genes are largely unknown.We previously identified 14 chimeric genes in D. melanogaster, which present candidates for studies of adaptation and the development of novel functions (5). Of these 14 genes, eight have appeared within the past 1 million years and are specific to D. melanogaster. These young chimeric genes formed recently in D. melanogaster and are the most likely of the 14 to have contributed to lineage-specific evolutionary changes. Here, we describe the recent formation and apparent fixation of one of these new chimeric genes, which we have named Quetzalcoatl (Qtzl) a...

SUMMARYChanges in transcriptional regulatory networks can significantly contribute to species evolution and adaptation. However, identification of genome-scale regulatory networks is an open challenge, especially in non-model organisms. Here, we introduce multi-species regulatory network learning (MRTLE), a computational approach that uses phylogenetic structure, sequence-specific motifs, and transcriptomic data, to infer the regulatory networks in different species. Using simulated data from known networks and transcriptomic data from six divergent yeasts, we demonstrate that MRTLE predicts networks with greater accuracy than existing methods because it incorporates phylogenetic information. We used MRTLE to infer the structure of the transcriptional networks that control the osmotic stress responses of divergent, non-model yeast species and then validated our predictions experimentally. Interrogating these networks reveals that gene duplication promotes network divergence across evolution. Taken together, our approach facilitates study of regulatory network evolutionary dynamics across multiple poorly studied species.

Samples of moss, lichens, liverworts and leaf litter collected in the Lower and Upper Peninsulas of the state of Michigan, USA, contained 28 species of water bears (phylum Tardigrada). Eighteen species were considered cosmopolitan, widely distributed in several biogeographical regions. One species, Minibiotus jonesorum sp. n., is described and illustrated. This new species is characterized by having ten transverse bands of polygonal pores that increase in size from anterior to posterior, three macroplacoids that increase in size from anterior to posterior and by lacking a microplacoid or leg granulation. The medial and posterior pores of M. jonesorum sp. n. are polygonal and much larger than the trefoil pores of M. furcatus, the most similar species in the genus.