Drosophila peripheral nerves, similar structurally to the peripheral nerves of mammals, comprise a layer of axons and inner glia, surrounded by an outer perineurial glial layer. Although it is well established that intercellular communication occurs among cells within peripheral nerves, the signaling pathways used and the effects of this signaling on nerve structure and function remain incompletely understood. Here we demonstrate with genetic methods that the Drosophila peripheral nerve is a favorable system for the study of intercellular signaling. We show that growth of the perineurial glia is controlled by interactions among five genes: ine, which encodes a putative neurotransmitter transporter; eag, which encodes a potassium channel; push, which encodes a large, Zn 2؉ -finger-containing protein; amn, which encodes a putative neuropeptide related to the pituitary adenylate cyclase activator peptide; and NF1, the Drosophila ortholog of the human gene responsible for type 1 neurofibromatosis. In other Drosophila systems, push and NF1 are required for signaling pathways mediated by Amn or the pituitary adenylate cyclase activator peptide. Our results support a model in which the Amn neuropeptide, acting through Push and NF1, inhibits perineurial glial growth, whereas the substrate neurotransmitter of Ine promotes perineurial glial growth. Defective intercellular signaling within peripheral nerves might underlie the formation of neurofibromas, the hallmark of neurofibromatosis.

A remarkable aspect of Dictyostelium development is that cells form evenly sized groups of approximately 2 x 10(4) cells. A secreted 450 kDa protein complex called counting factor (CF) regulates the number of cells per group. We find that CF regulates group size by repressing cell-cell adhesion. In both experiments and computer simulations, high levels of CF (and thus low adhesion) result in aggregation streams breaking up into small groups, while no CF (and thus high adhesion) results in no stream breakup and large groups. These results suggest that in Dictyostelium and possibly other systems a secreted factor regulating cell-cell adhesion can regulate the size of a group of cells.

Due to the COVID-19 pandemic, Rice University canceled classes for the week of March 9–13, 2020 and shifted all instruction to online only following spring break. For the second half of the semester, animal physiology was taught exclusively over Zoom. Here we describe how a flipped teaching format that was used before the pandemic eased the transition from face-to-face teaching to online instruction. The preclass preparation resources and the active learning materials that were already in place for flipped teaching were helpful in the transition to solely online teaching. Therefore, the focus during the transition was to reconfigure active learning and examinations from the face-to-face format to the online platform. Instead of small group discussions in the classroom, teams interacted in Zoom Breakout Rooms. Rather than taking exams in-person during scheduled class time, students submitted exams online. Additionally, students prerecorded their project presentations instead of presenting them “live” during the last week of classes. Overall, students felt that the class smoothly transitioned to a remote only format. These and other changes to the instructional methods will be implemented during the Spring 2021 semester when the course is taught fully online.