Drosophila melanogaster cloak their eggs with pheromones, which prevents cannibalism

This is the final version. Available from Public Library of Science via the DOI in this recordData Availability: All relevant data are within the paper and its Supporting Information files: S1 Data and S2 Data.Oviparous animals across many taxa have evolved diverse strategies that deter egg predation, providing valuable tests of how natural selection mitigates direct fitness loss. Communal egg laying in nonsocial species minimizes egg predation. However, in cannibalistic species, this very behavior facilitates egg predation by conspecifics (cannibalism). Similarly, toxins and aposematic signaling that deter egg predators are often inefficient against resistant conspecifics. Egg cannibalism can be adaptive, wherein cannibals may benefit through reduced competition and added nutrition, but since it reduces Darwinian fitness, the evolution of anticannibalistic strategies is rife. However, such strategies are likely to be nontoxic because deploying toxins against related individuals would reduce inclusive fitness. Here, we report how D. melanogaster use specific hydrocarbons to chemically mask their eggs from cannibal larvae. Using an integrative approach combining behavioral, sensory, and mass spectrometry methods, we demonstrate that maternally provisioned pheromone 7,11-heptacosadiene (7,11-HD) in the eggshell’s wax layer deters egg cannibalism. Furthermore, we show that 7,11-HD is nontoxic, can mask underlying substrates (for example, yeast) when coated upon them, and its detection requires pickpocket 23 (ppk23) gene function. Finally, using light and electron microscopy, we demonstrate how maternal pheromones leak-proof the egg, consequently concealing it from conspecific larvae. Our data suggest that semiochemicals possibly subserve in deceptive functions across taxa, especially when predators rely on chemical cues to forage, and stimulate further research on deceptive strategies mediated through nonvisual sensory modules. This study thus highlights how integrative approaches can illuminate our understanding on the adaptive significance of deceptive defenses and the mechanisms through which they operate.Swiss National Science FoundationEuropean Research CouncilDeutsche ForschungsgemeinschaftBaden Württemberg Stiftung and Zukunftskolleg of the University of Konstan

Increased throughput and ultra-high mass resolution in DESI FT-ICR MS imaging through new-generation external data acquisition system and advanced data processing approaches

Desorption electrospray ionisation-mass spectrometry imaging (DESI-MSI) is a powerful imaging technique for the analysis of complex surfaces. However, the often highly complex nature of biological samples is particularly challenging for MSI approaches, as options to appropriately address mass spectral complexity are limited. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) offers superior mass accuracy and mass resolving power, but its moderate throughput inhibits broader application. Here we demonstrate the dramatic gains in mass resolution and/or throughput of DESI-MSI on an FT-ICR MS by developing and implementing a sophisticated data acquisition and data processing pipeline. The presented pipeline integrates, for the first time, parallel ion accumulation and detection, post-processing absorption mode Fourier transform and pixel-by-pixel internal re-calibration. To achieve that, first, we developed and coupled an external high-performance data acquisition system to an FT-ICR MS instrument to record the time-domain signals (transients) in parallel with the instrument’s built-in electronics. The recorded transients were then processed by the in-house developed computationally-efficient data processing and data analysis software. Importantly, the described pipeline is shown to be applicable even to extremely large, up to 1 TB, imaging datasets. Overall, this approach provides improved analytical figures of merits such as: (i) enhanced mass resolution at no cost in experimental time; and (ii) up to 4-fold higher throughput while maintaining a constant mass resolution. Using this approach, we not only demonstrate the record 1 million mass resolution for lipid imaging from brain tissue, but explicitly demonstrate such mass resolution is required to resolve the complexity of the lipidome

Metabolic profiling of Peperoni di Senise PGI bell peppers with ultra-high resolution absorption mode Fourier transform ion cyclotron resonance mass spectrometry

Bell peppers (genus Capsicum) are an excellent source of health-related compounds, such as ascorbic acid (vitamin C), carotenoids (provitamin A), tocopherols (vitamin E), flavonoids and capsaicinoids. These compounds are known for their biological activities, including antioxidant, anti-inflammatory and anticarcinogenic properties. Over the past decade, there has been an increasing number of studies focused on metabolite profiling of bell peppers. However, none of the direct analysis methods exploited in these studies were capable of simultaneously detecting compounds belonging to more than four metabolite classes (and possible derivatives of model compounds) present in bell peppers, i.e. mainly amino acids, sugars, polyphenols and organic acids. We have attempted to profile a higher number of metabolite classes by performing a direct-injection analysis with a Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), on Peperoni di Senise bell peppers (Capsicum annuum L.). These bell peppers are a typical food product cultivated in Basilicata (Southern Italy), protected with a protected geographical indication (PGI) quality mark and known for their unique taste. To increase the performance of the FT-ICR MS method, we processed the recorded time-domain ion signals (transients) into the absorption mode FT-ICR mass spectra. The latter was achieved by the use of the dedicated software package, AutoVectis Pro. Mass spectral representation in absorption mode produced a more comprehensive description of the metabolic profile of Peperoni di Senise PGI by improving results reli-ability via artifacts removal and identifying a higher number of compounds. (c) 2021 Elsevier B.V. All rights reserved