Host autophagy mediates organ wasting and nutrient mobilization for tumor growth.

During tumor growth-when nutrient and anabolic demands are high-autophagy supports tumor metabolism and growth through lysosomal organelle turnover and nutrient recycling. Ras-driven tumors additionally invoke non-autonomous autophagy in the microenvironment to support tumor growth, in part through transfer of amino acids. Here we uncover a third critical role of autophagy in mediating systemic organ wasting and nutrient mobilization for tumor growth using a well-characterized malignant tumor model in Drosophila melanogaster.

Natural abundance isotope ratios to differentiate sources of carbon used during tumor growth in vivo.

Background: Radioactive or stable isotopic labeling of metabolites is a strategy that is routinely used to map the cellular fate of a selected labeled metabolite after it is added to cell culture or to the circulation of an animal. However, a labeled metabolite can be enzymatically changed in cellular metabolism, complicating the use of this experimental strategy to understand how a labeled metabolite moves between organs. These methods are also technically demanding, expensive and potentially toxic.

Plant growth chamber design for subambient pCO and δ C studies.

Rationale: Subambient pCO has persisted across the major Phanerozoic ice ages, including the entire late Cenozoic (ca 30 Ma to present). Stable isotope analysis of plant-derived organic matter is used to infer changes in pCO and climate in the geologic past, but a growth chamber that can precisely control environmental conditions, including pCO and δ C value of CO (δ C ) at subambient pCO , is lacking.

Methods: We designed and built five identical chambers specifically for plant growth under stable subambient pCO (ca 100 to 400 ppm) and δ C conditions.

Carbon and nitrogen stable isotopes in U.S. milk: Insight into production process.

Rationale: Stable isotope analysis (SIA), a potential method of verifying the geographic origin and production method of dairy products, has not been applied to United States (U.S.) dairy samples on a national scale.

Large-scale plant growth chamber design for elevated pCO2 and δ13C studies.

Rationale: Throughout at least the next century, CO(2) fertilization and environmental stresses (e.g. nutrient, moisture, insect herbivory) are predicted to affect yields of economically important crop species.

Elimination of nitrogen interference during online oxygen isotope analysis of nitrogen-doped organics using the "NiCat" nickel reduction system.

Rationale: Accurate online analysis of the δ(18)O values of nitrogen-bearing organic compounds is of interest to several emergent fields, including ecology, forensics and paleontology. During online analysis, high-temperature conversion (HTC) of nitrogen-bearing organics produces N(2) gas which creates isobaric interference with the isotopic measurement. Specifically, N(2) reacts with trace amounts of oxygen in the mass spectrometer source to form (14)N(16)O (m/z 30), which prevents accurate evaluation of the sample (12)C(18)O peak (m/z 30).

Offline oxygen isotope analysis of organic compounds with high N:O.

Although the advantages of online δ(18)O analysis of organic compounds make its broad application desirable, researchers have encountered NO(+) isobaric interference with CO(+) at m/z 30 (e.g. (14)N(16)O(+), (12)C(18)O(+)) when analyzing nitrogenous substrates.

Minimization of sample requirement for delta18O in benzoic acid.

The measurement of the oxygen stable isotope content in organic compounds has applications in many fields, ranging from paleoclimate reconstruction to forensics. Conventional High-Temperature Conversion (HTC) techniques require >20 microg of O for a single delta(18)O measurement. Here we describe a system that converts the CO produced by HTC into CO(2) via reduction within a Ni-furnace.