Mapping an atlas of tissue-specific drosophila melanogaster metabolomes by high resolution mass spectrometry

Metabolomics can provide exciting insights into organismal function, but most work on simple models has focussed on the whole organism metabolome, so missing the contributions of individual tissues. Comprehensive metabolite profiles for ten tissues from adult Drosophila melanogaster were obtained here by two chromatographic methods, a hydrophilic interaction (HILIC) method for polar metabolites and a lipid profiling method also based on HILIC, in combination with an Orbitrap Exactive instrument. Two hundred and forty two polar metabolites were putatively identified in the various tissues, and 251 lipids were observed in positive ion mode and 61 in negative ion mode. Although many metabolites were detected in all tissues, every tissue showed characteristically abundant metabolites which could be rationalised against specific tissue functions. For example, the cuticle contained high levels of glutathione, reflecting a role in oxidative defence; the alimentary canal (like vertebrate gut) had high levels of acylcarnitines for fatty acid metabolism, and the head contained high levels of ether lipids. The male accessory gland uniquely contained decarboxylated S-adenosylmethionine. These data thus both provide valuable insights into tissue function, and a reference baseline, compatible with the FlyAtlas.org transcriptomic resource, for further metabolomic analysis of this important model organism, for example in the modelling of human inborn errors of metabolism, aging or metabolic imbalances such as diabetes

The extraction of work from quantum coherence

The interplay between quantum-mechanical properties, such as coherence, and classical notions, such as energy, is a subtle topic at the forefront of quantum thermodynamics. The traditional Carnot argument limits the conversion of heat to work; here we critically assess the problem of converting coherence to work. Through a careful account of all resources involved in the thermodynamic transformations within a fully quantum-mechanical treatment, we show that there exist thermal machines extracting work from coherence arbitrarily well. Such machines only need to act on individual copies of a state and can be reused. On the other hand, we show that for any thermal machine with finite resources not all the coherence of a state can be extracted as work. However, even bounded thermal machines can be reused infinitely many times in the process of work extraction from coherence

Quasi-autonomous quantum thermal machines and quantum to classical energy flow

There are both practical and foundational motivations to consider the thermodynamics of quantum systems at small scales. Here we address the issue of autonomous quantum thermal machines that are tailored to achieve some specific thermodynamic primitive, such as work extraction in the presence of a thermal environment, while having minimal or no control from the macroscopic regime. Beyond experimental implementations, this provides an arena in which to address certain foundational aspects such as the role of coherence in thermodynamics, the use of clock degrees of freedom and the simulation of local time-dependent Hamiltonians in a particular quantum subsystem. For small-scale systems additional issues arise. Firstly, it is not clear to what degree genuine ordered thermodynamic work has been extracted, and secondly non-trivial back-actions on the thermal machine must be accounted for. We find that both these aspects can be resolved through a judicious choice of quantum measurements that magnify thermodynamic properties up the ladder of length-scales, while simultaneously stabilising the quantum thermal machine. Within this framework we show that thermodynamic reversibility is obtained in a particular Zeno limit, and finally illustrate these concepts with a concrete example involving spin systems

Relatively abundant polar metabolites in male accessory glands.

<p>*In source fragment for methylthioadenosine. Data are presented as a heat-map of peak areas, from red (>1×10⁷) to blue (<1×10³).</p

Major metabolites in cuticle.

<p>(A) Relatively abundant polar metabolites in cuticle. Data are presented as a heat-map of peak areas, from red (>2×10⁷) to blue (<5×10³). (B) Relatively abundant lipids in cuticle. Data are presented as a heat-map of peak areas, from red (>1×10⁷) to blue (<5×10³).</p

Extracted ion chromatograms showing GSH and its precursors extracted from Drosophila cuticle.

<p>Extracted ion chromatograms showing GSH and its precursors extracted from Drosophila cuticle.</p

Relatively abundant lipids in crop.

<p>PA = phosphatidic acid. Data are presented as a heat-map of peak areas, from red (>1×10⁷) to blue (<5×10³).</p

Major metabolites in ovaries.

<p>(A) Relatively abundant polar metabolites in Drosophila ovaries. *In source GSH fragment formed. **In source GSH fragment formed. Data are presented as a heat-map of peak areas, from red (>2×10⁷) to blue (<5×10³). (B) Relatively abundant lipids in <i>Drosophila</i> ovary. PG = phosphoglycerol; GPG = glyceryl phosphoglycerol; PI = phosphoinositol; Cer = ceramide. Data are presented as a heat-map of peak areas, from red (>1×10⁷) to blue (<1×10³).</p

Major metabolites in testes.

<p>(A) Testes relatively abundant polar metabolites. *Gives guanine as an in source fragment ion. **Isomeric with adenosine which but elutes earlier gives guanine as an in source fragment ion. Data are presented as a heat-map of peak areas, from red (>1×10⁷) to blue (<5×10³). (B) Relatively abundant lipids in testes. Data are presented as a heat-map of peak areas, from red (>1×10⁷) to blue (<1×10³).</p