Using Artificial Selection to Understand Orientation Behavior in Drosophila

Several studies suggest that the fruit fly Drosophila melanogaster can use magnetic fields for orientation1-4; however, the responses to magnetic fields are not consistent across studies and experiments investigating the mechanism of magnetoreception rely on magnetic fields that are at least 10 times stronger than the magnetic field of the Earth5-6. We are attempting to determine whether Drosophila have the ability to detect Earth-strength magnetic fields by running flies through a progressive Y-maze and then selectively breeding the flies based on their choices in the maze. There are two main hypotheses about the mechanism of magnetoreception in animals. The first is based on the use of magnetite, which forms long chains and serves as a magnetic dipole and has been found in organisms such as bats7. The other hypothesis is based on a light-dependent magnetic response utilizing the cryptochromephotoreceptor8. While the predominant hypothesis is that fruit flies use cryptochrome to detect magnetic fields1-6, experimental results have shown that most invertebrates use magnetite or both magnetite and cryptochrome

Paternò–Büchi Reaction Mass Spectrometry Enables Positional Assignment of Polymethylene-Interrupted Double Bonds in Food-Derived Lipids

Fatty acids (FAs) containing polymethylene-interrupted (PMI) double bonds are a component of human foods; however, they present a significant analytical challenge for de novo identification. Covalent adduct chemical ionization and ozone-induced dissociation mass spectrometry (MS) methods enable unambiguous assignment of PMI-FA double bond positions, however, no method has been reported with electrospray ionization (ESI) platform using off-the-shelf systems. In the current work, we studied the Paternò–Büchi (PB) fragmentation patterns of PMI-FA and triacylglycerol (TG) by analyzing several known food sources. PB-MS/MS and MS3 enabled complete double bond location assignments, including the isolated double bond in PMI-FA and triacylglycerols. Sea urchin (“uni”), oyster, pine nut, and ginkgo nut were characterized for their signature PMI-FA, 20:2­(5Z,11Z), 22:2­(7Z, 15Z), 18:3­(5Z,9Z,12Z), and 20:3­(5Z,11Z,14Z), respectively. Quantitative analyses of the relative abundance of these PMI-FA led to results similar to reference methods. 18:3­(5Z,9Z,12Z) was enriched at the sn-1/sn-3 position in pine nut major TG

Amplification of Drosophila Olfactory Responses by a DEG/ENaC Channel

Insect olfactory receptors operate as ligand-gated ion channels that directly transduce odor stimuli into electrical signals. However, in the absence of any known intermediate transduction steps, it remains unclear whether and how these ionotropic inputs are amplified in olfactory receptor neurons (ORNs). Here, we find that amplification occurs in the Drosophila courtship-promoting ORNs through Pickpocket 25 (PPK25), a member of the degenerin/epithelial sodium channel family (DEG/ENaC). Pharmacological and genetic manipulations indicate that, in Or47b and Ir84a ORNs, PPK25 mediates Ca2+-dependent signal amplification via an intracellular calmodulin-binding motif. Additionally, hormonal signaling upregulates PPK25 expression to determine the degree of amplification, with striking effects on male courtship. Together, these findings advance our understanding of sensory neurobiology by identifying an amplification mechanism compatible with ionotropic signaling. Moreover, this study offers new insights into DEG/ENaC activation by highlighting a novel means of regulation that is likely conserved across species