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Flow cytometry estimates of genome sizes among species of Drosophila show a 3-fold variation, ranging from ∼127 Mb in Drosophila mercatorum to ∼400 Mb in Drosophila cyrtoloma. However, the assembled portion of the Muller F element (orthologous to the fourth chromosome in Drosophila melanogaster) shows a nearly 14-fold variation in size, ranging from ∼1.3 Mb to >18 Mb. Here, we present chromosome-level long-read genome assemblies for 4 Drosophila species with expanded F elements ranging in size from 2.3 to 20.5 Mb. Each Muller element is present as a single scaffold in each assembly. These assemblies will enable new insights into the evolutionary causes and consequences of chromosome size expansion.

 

The Genomics Education Partnership (GEP; https://thegep.org) began as a consortium of 16 faculty in 2006 with a goal of providing students with Course-based Undergraduate Research Experiences (CUREs) in genomics. Today, GEP has over 200 faculty from more than 180 institutions and engages more than 3,900 undergraduates in authentic genomics research annually. These faculty joined and continued to participate in the GEP for many reasons, including the collaborative nature of the research, the well-established infrastructure, and the supportive network of like-minded colleagues. Faculty implement GEP materials in diverse settings ? ranging from short modules (2-8 weeks) within a course, to a standalone full-semester course, to independent student research. GEP students show significant gains in scientific knowledge and attitudes toward science. In addition to improving their understanding of the research process and how new knowledge is created in the field, GEP students acquire desirable and transferable skills essential for future participation in the workforce, such as problem solving, independence, application of knowledge, team-work, and collaboration. Students also gain competence in the use of computational algorithms to analyze large biological datasets ? thereby preparing students for a growing need of a workforce trained at applying statistics and computational tools to analyze large datasets. In addition, GEP students and their faculty mentors are eligible to be co-authors on the scientific publications that are based on their work. In this workshop, we will provide an overview of the GEP community, a hands-on guided tour of our introductory curriculum aimed to teach gene structure, transcription, translation, and processing, and a step-by-step walkthrough that illustrates the protocol for annotating a protein-coding gene in Drosophila. Participants will receive information on how to join the GEP community and receive training and resources to enable their implementations. 

Understanding how and when key novel adaptations evolved is a central goal of evolutionary biology. Within theimmigrans‐tripunctataradiation ofDrosophila, many mushroom‐feeding species are tolerant of host toxins, such as cyclopeptides, that are lethal to nearly all other eukaryotes. In this study, we used phylogenetic and functional approaches to investigate the evolution of cyclopeptide tolerance in theimmigrans‐tripunctataradiation ofDrosophila. First, we inferred the evolutionary relationships among 48 species in this radiation using 978 single copy orthologs. Our results resolved previous incongruities within species groups across the phylogeny. Second, we expanded on previous studies of toxin tolerance by assaying 16 of these species for tolerance to α‐amanitin and found that six of them could develop on diet with toxin. Finally, we asked how α‐amanitin tolerance might have evolved across theimmigrans‐tripunctataradiation, and inferred that toxin tolerance was ancestral in mushroom‐feedingDrosophilaand subsequently lost multiple times. Our findings expand our understanding of toxin tolerance across theimmigrans‐tripunctataradiation and emphasize the uniqueness of toxin tolerance in this adaptive radiation and the complexity of biochemical adaptations.

 

Annotating the genomes of multiple species allows us to analyze the evolution of their genes. While many eukaryotic genome assemblies already include computational gene predictions, these predictions can benefit from review and refinement through manual gene annotation. The Genomics Education Partnership (GEP; https://thegep.org/ ) developed a structural annotation protocol for protein-coding genes that enables undergraduate student and faculty researchers to create high-quality gene annotations that can be utilized in subsequent scientific investigations. For example, this protocol has been utilized by the GEP faculty to engage undergraduate students in the comparative annotation of genes involved in the insulin signaling pathway in 27 Drosophila species, using D. melanogaster as the reference genome. Students construct gene models using multiple lines of computational and empirical evidence including expression data (e.g., RNA-Seq), sequence similarity (e.g., BLAST and multiple sequence alignment), and computational gene predictions. Quality control measures require each gene be annotated by at least two students working independently, followed by reconciliation of the submitted gene models by a more experienced student. This article provides an overview of the annotation protocol and describes how discrepancies in student submitted gene models are resolved to produce a final, high-quality gene set suitable for subsequent analyses. The protocol can be adapted to other scientific questions (e.g., expansion of the Drosophila Muller F element) and species (e.g., parasitoid wasps) to provide additional opportunities for undergraduate students to participate in genomics research. These student annotation efforts can substantially improve the quality of gene annotations in publicly available genomic databases. 

The bacterial gut microbiota of many animals is known to be important for many physiological functions including detoxification. The selective pressures imposed on insects by exposure to toxins may also be selective pressures on their symbiotic bacteria, who thus may contribute to the mechanism of toxin tolerance for the insect. Amatoxins are a class of cyclopeptide mushroom toxins that primarily act by binding to RNA polymerase II and inhibiting transcription. Several species of mycophagousDrosophilaare tolerant to amatoxins found in mushrooms of the genusAmanita, despite these toxins being lethal to most other known eukaryotes. These species can tolerate amatoxins in natural concentrations to utilize toxic mushrooms as larval hosts, but the mechanism by which these species are tolerant remains unknown. Previous data have shown that a local population ofD. tripunctataexhibits significant genetic variation in toxin tolerance. This study assesses the potential role of the microbiome in α‐amanitin tolerance in six wild‐derived strains ofDrosophila tripunctata. Normal and antibiotic‐treated samples of six strains were reared on diets with and without α‐amanitin, and then scored for survival from the larval stage to adulthood and for development time to pupation. Our results show that a substantial reduction in bacterial load does not influence toxin tolerance in this system, while confirming genotype and toxin‐specific effects on survival are independent of the microbiome composition. Thus, we conclude that this adaptation to exploit toxic mushrooms as a host is likely intrinsic to the fly's genome and not a property of their microbiome.

 

ABSTRACT The initial phase of the COVID-19 pandemic changed the nature of course delivery from largely in-person to exclusively remote, thus disrupting the well-established pedagogy of the Genomics Education Partnership (GEP; https://www.thegep.org ). However, our web-based research adapted well to the remote learning environment. As usual, students who engaged in the GEP’s Course-based Undergraduate Research Experience (CURE) received digital projects based on genetic information within assembled Drosophila genomes. Adaptations for remote implementation included moving new member faculty training and peer Teaching Assistant office hours from in-person to online. Surprisingly, our faculty membership significantly increased and, hence, the number of supported students. Furthermore, despite the mostly virtual instruction of the 2020–2021 academic year, there was no significant decline in student learning nor attitudes. Based on successfully expanding the GEP CURE within a virtual learning environment, we provide four strategic lessons we infer toward democratizing science education. First, it appears that increasing access to scientific research and professional development opportunities by supporting virtual, cost-free attendance at national conferences attracts more faculty members to educational initiatives. Second, we observed that transitioning new member training to an online platform removed geographical barriers, reducing time and travel demands, and increased access for diverse faculty to join. Third, developing a Virtual Teaching Assistant program increased the availability of peer support, thereby improving the opportunities for student success. Finally, increasing access to web-based technology is critical for providing equitable opportunities for marginalized students to fully participate in research courses. Online CUREs have great potential for democratizing science education. 

Understanding plant‐insect interactions is an active area of research in both ecology and evolution. Much attention has been focused on the impact of secondary metabolites in the host plant or fungi on these interactions. Plants and fungi contain a variety of biologically active compounds, and the secondary metabolite profile can vary significantly between individual samples. However, many experiments characterize the biological effects of only a single secondary metabolite or a subset of these compounds.

Here, we develop an exhaustive extraction protocol using an accelerated solvent extraction protocol to recover the complete suite of cyclopeptides and other secondary metabolites found inAmanita phalloides(death cap mushrooms) and compare its efficacy to the “Classic” extraction method used in earlier works.

We demonstrate that our extraction protocol recovers the full suite of cyclopeptides and other secondary metabolites inA. phalloidesunlike the “Classic” method that favors polar cyclopeptides.

Based on these findings, we provide recommendations for how to optimize protocols to ensure exhaustive extracts and also the best practices when using natural extracts in ecological experiments.