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Herein, we improve the procedure for organic rice authentication using compound-specific δ13C and δ15N analyses of fatty acids and amino acids, addressing the increasing demand for accurate methods to confirm organic authenticity. Organic rice (OR) and pesticide-free rice (PFR) featured higher values of δ15Nbulk than conventional rice (CR), whereas the corresponding differences between OR and PFR were insignificant. Additionally, OR, PFR, and CR could be discriminated based on some δ13Camino-acid and δ15Namino-acid values. δ13Cbulk was correlated with most δ13Cfatty-acid (r ≥ 0.596) values, and δ15Nbulk was strongly correlated with most δ15Namino-acid (r ≥ 0.834) values. The first component in the orthogonal projection to latent structure-discriminant analysis model allowed for a clear separation between OR and PFR, and good predictability (Q2Y = 0.506). Thus, the present study improves the reliability of organic authentication when bulk stable isotope ratio analysis alone is insufficient for the accurate discrimination of OR, PFR, and CR.

In countries like South Korea and the USA, origin labeling of shiitake grown using imported Chinese-inoculated medium is an issue. Therefore, we evaluated the use of compound-specific isotope analysis (CSIA) for the accurate identification of the geographical origin of shiitake (Korean, Chinese-inoculated medium, and Chinese); Chinese-inoculated medium shiitake were cultivated in Korea using inoculated sawdust medium from China. The CSIA-discriminant model showed an overall accuracy of 100% in the geographical classification of the original set and 96.4% for the cross-validated set. Glutamate and aspartate δ15N values were the most important variables for differentiating shiitake based on their origins. Compared to that observed upon using the bulk stable isotope analysis, the CSIA model was associated with significantly improved predictability of origin identification. Our findings elucidate the importance of isotope signatures in developing a reliable origin labeling method for shiitake cultured on the sawdust medium for the global market.

We analyzed the water extracts of the recently fallen Mukundpura (MK) meteorite and searched for amino-, hydroxy- and carboxylic acids, amines and their possible enantiomeric excesses. All water-soluble compounds detected so far were found to have distributions similar to those identified in Murchison, with the main compositional differences of lower yields overall and absence in MK of longer chain compounds. Enantiomeric excesses were detected in MK for (S) isovaline and (S) sec-butylamine, the compounds that displayed them in several CM and CR chondrites. We also obtained a preliminary survey of MK hydrocarbons by extracting with solvent their water-extracted powders. MK hydrocarbons presented a suite containing far fewer linear species and is dominated by likely contaminants branched alkanes. Given the large variability of abundances and ee values reported so far within and between meteorites, repeat analyses of MK stones will be needed to better evaluate their extent in the new meteorite.

We searched the ethanol extracts of the Murchison meteorite for propylene oxide (PrOx), the only chiral molecule discovered so far outside solar environments, and detected its likely derivative after isolation of the low boiling components of the extract. This compound is also chiral and, upon hydrolysis, produces propylene glycol (PrGl), the expected product of PrOx under these conditions. Both the PrOx derivative and PrGl were detected with variable enantiomeric excesses (ee) averaging at ∼10% and to have the (R)(+) configuration, i.e., for the same optical isomer as for sugars in the biosphere and sugar derivatives in meteorites. Besides PrGl, the hydrolysates also contained homologous compounds and polymeric materials with the combined δD (‰) of +235 and +65, respectively, suggesting a yet unknown compositional complexity in meteorites. The occurrence of ee in interstellar PrOx cannot be ascertained with current spectroscopic methodologies, however, the overall data reported here would allow to imply it.

RATIONALE Within the last decade, applications of compound-specific stable isotope analysis of nitrogen (δ15 N values) in amino acids (CSIA-AA) have developed rapidly, particularly within organismal ecology. Unlike with bulk stable isotope analysis (BSIA), the reproducibility of δ15 N-AA measurements has not been critically assessed. Two primary concerns include the diversity of techniques available for the derivatization of amino acids prior to analysis by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) and the myriad of standardization practices and quality assurance procedures used across studies. METHODS We examined the relative effect of three normalization procedures, (1) internal reference calibration, (2) compound-specific calibration, and (3) scale-normalization, on the accuracy and precision of δ15 N-AA measurements by GC/C/IRMS and the comparability of δ15 N-AA measurements by two derivatization techniques, methoxycarbonylation-esterification and acetylation-esterification, across a range of organisms. RESULTS The overall accuracy and precision of δ15 N-AA measurements were improved following both compound-specific calibration and scale-normalization, as was the comparability of δ15 N-AA measurements of individual amino acids between derivatization techniques across organisms. The mean difference of scale-normalized δ15 N-AA values across all organisms between the two derivatization techniques was 0.19‰, much less than the typical analytical error associated with δ15 N-AA measurements (±1‰). CONCLUSIONS: Adoption of standardized calibration procedures will be important to establishing reproducibility in δ15 N-AA measurements, particularly across derivatization techniques. It is both technically practical and desirable for users of CSIA-AA to adopt practices in quality control and assessment similar to those outlined for BSIA, including the compound-specific calibration of δ15 N-AA values, followed by scale-normalization. Copyright © 2017 John Wiley & Sons, Ltd.

Diet may be a significant determinant of insect gut microbiome composition. However, the extent to which dietary shifts shape both the composition and relevant functions of insect gut microbiomes, and ultimately, impact host energy balance (i.e., metabolic phenotype) is not well understood. We investigated the impacts of diet switching on Diploptera punctata females maintained on dog food (DF) diet relative to those fed a comparatively sub-optimal cellulose-amended dog food (CADF) diet for four weeks. After this period, dietary shift resulted in a significantly higher average mass-specific standard metabolic rate (SMR) in CADF-fed females compared to DF-fed females. We also uncovered significant 13C-enrichment in DF-fed insect samples relative to CADF-fed insect samples and lowered bacterial essential amino acid (EAA) provisioning in CADF-fed samples. Differences in SMR and EAA provisioning were not accompanied by significant differences in overall microbiome composition between the two groups. However, cellulolytic and nitrogen-fixing bacterial families dominant in wild omnivorous cockroaches and wood-feeding termites were significantly enriched in CADF-fed females than in DF-fed females, at the end of the study. We propose that these changes in microbiome composition after dietary shifts are associated with changes in EAA provisioning and possibly SMR. Further studies are needed to comprehensively understand the relative importance of gut microbial functions among the complexity of factors known to underscore SMR responses in insects under varying dietary conditions.

Chiral homogeneity is essential to the structure and function of terrestrial biopolymers but the origin of this “homochirality” is poorly understood and remains one of the many unknowns surrounding the origins of life. Several amino acids extracted from Carbonaceous Chondrite meteorites display l -enantiomeric excesses ( ee ) and their findings have encouraged suggestions that an input of non-racemic meteoritic compounds to early Earth might have led to terrestrial homochirality. Motivated by occasional indications of possible ee in other classes of soluble meteoritic compounds, we have undertaken a systematic study of the chiral distribution of amines in Renazzo-type (CR) meteorites, where they are the second most abundant organic molecular species and ammonia is by far the most abundant single molecule. We report here the first time finding of l - ee for two chiral amines in several pristine CR meteorites from Antarctica and outline a proposal by which the compounds possibly formed from the same ketone precursors as some of the chiral amino acids. This would occur during a warm hydrous stage of the asteroidal parent body, via a reductive amination process in the presence of a large abundance of ammonia, where the precursors' adsorption upon mineral phases possessing asymmetry offered the opportunity for chiral induction. Because the precursor ketones are achiral, the proposal underscores the likelihood of diverse asymmetric influences and processes in cosmochemistry.

The present study describes compound-specific δ13C and δ15N analyses of fatty acids and amino acids for improving the accurate authentication of organic milk (OM) against conventional milk (CM) col...

Herein, we improve the procedure for organic rice authentication using compound-specific δ

Here we evaluate the quantitative relationship between carbon isotopic fractionation and anoxic biodegradation of phthalate esters (PAEs), a kind of endocrine disruptors. The stable carbon isotope delta values ( δ 13 C) of 4 PAEs, i.e. di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di- n -butyl phthalate (DBP), and di- iso -butyl phthalate (DiBP), were analyzed during biodegradation by a pure bacteria strain isolated from the shallow aquifer sediment in anoxic condition. Results showed that the carbon isotopic fractionation in the initial degradation of PAEs was well-described by the Rayleigh equation model with R 2 from 0.8885 to 0.9821. The carbon isotopic fractionation ( e ) for DMP and DEP were −4.6 ± 0.4‰ and −2.9 ± 0.1‰, respectively, while DBP and DiBP showed limited isotopic fractionation. A linear relationship between e values and the total carbon atoms present in straight-carbon-chain PAE molecules with R 2 of 0.9918. The apparent kinetic isotope effects (AKIEs) were calculated for proposed 4 initial transformation pathways of PAEs. The high carbon AKIEs of 1.048 and 1.036 were obtained for single enzymatic hydrolysis of DMP and DEP, respectively, and fell in the expected KIE range of 1.03–1.09. However, the intrinsic carbon isotope effects for enzymatic hydrolysis of DBP and DiBP might be masked.

Organizational structure for the proposed IsoBank. A central executive group would oversee four subcommittees (SC): Information technology, integrative disciplinary, education and training, and analytical expertise. GNIP, Global Network of Isotopes in Precipitation; IAEA, International Atomic Energy Association; QA/QC, quality assurance/quality control.

RATIONALE In recent years, research and applications of the N2O site-specific nitrogen isotope composition have advanced, reflecting awareness of the contribution of N2O to the anthropogenic greenhouse effect, and leading to significant progress in instrument development. Further dissemination of N2O isotopomer analysis, however, is hampered by a lack of internationally agreed gaseous N2O reference materials and an uncertain compatibility of different laboratories and analytical techniques. METHODS In a first comparison approach, eleven laboratories were each provided with N2O at tropospheric mole fractions (target gas T) and two reference gases (REF1 and REF2). The laboratories analysed all gases, applying their specific analytical routines. Compatibility of laboratories was assessed based on N2O isotopocule data for T, REF1 and REF2. Results for T were then standardised using REF1 and REF2 to evaluate the potential of N2O reference materials for improving compatibility between laboratories. RESULTS Compatibility between laboratories depended on the analytical technique: isotope ratio mass spectrometry (IRMS) results showed better compatibility for δ(15)N values, while the performance of laser spectroscopy was superior with respect to N2O site preference. This comparison, however, is restricted by the small number of participating laboratories applying laser spectroscopy. Offset and two-point calibration correction of the N2O isotopomer data significantly improved the consistency of position-dependent nitrogen isotope data while the effect on δ(15)N values was only minor. CONCLUSIONS The study reveals that for future research on N2O isotopocules, standardisation against N2O reference material is essential to improve interlaboratory compatibility. For atmospheric monitoring activities, we suggest N2O in whole air as a unifying scale anchor.

RATIONALE Compound-specific stable isotope analysis of amino acids has proven informative to many ecological systems, but only a handful of analytical methods are routinely employed. We evaluated a simple, rapid procedure in which biological samples undergo short-duration acid hydrolysis and the resulting amino acids are derivatized with methyl chloroformate for gas chromatography/combustion/isotope-ratio mass spectrometry (GC/C/IRMS). METHODS Amino acid derivatives were separated on a polar gas chromatography column, combusted, and δ13C and δ15N values were measured. Tests of reproducibility and accuracy were conducted for amino acid reference mixtures and biological samples. A brief case study of turtles was used to assess whether isotopic data were consistent with a priori ecological expectations. RESULTS The methyl chloroformate based reaction successfully converted 15 amino acids from acid hydrolysates of biological materials into separable derivatives. The δ13C and δ15N values had high average measurement precision (σ

Rationale The carbon and hydrogen isotopes of methane are useful in differentiating biological (e.g. wetlands, ruminants, biomass burning) and geological methane sources (e.g. fossil fuels, gas hydrates), as well as quantifying pathways of methanotrophism. Continuous-flow isotopic measurements of methane present a set of analytical challenges, including sample size restrictions and separation of CH4 from atmosphere, hydrocarbons, and CO2 . Methods Small-scale modifications were made to a commercial trace-gas preconcentration and sampling unit (Thermo Scientific PreCon-GasBench) for improved isotopic analysis of methane (δ(13)C/δ(2)H) across a range of gas concentrations. Results The long-term reproducibility of δ(13)C-CH4 values is less than ±0.2‰ (1σ). The limit-of-quantitation of δ(13)C-CH4 values is less than 0.8 nmol, conveniently measurable within standard gas sampling vials. A reproducibility of better than ±4‰ (1σ) is regularly achieved for δ(2) H values from sample sizes greater than 2 nmol. The range of measurement, for both δ(13)C and δ(2)H values, is easily extended from ambient concentration (~1.7 ppm-v) for preconcentrated samples to percent methane concentrations under subsampling. Conclusions The automated measurement of δ(13)C-CH4 and δ(2)H-CH4 values, from ambient to percentage concentrations, is possible with minimal modifications to a commercial preconcentration/gas chromatography inlet. Sample matrix interferences (CO2 , Cn Hy , air) are eliminated and simultaneous isotopic measurements of methane and CO2 and/or C1 -C4 light hydrocarbons are possible, while still retaining functionality for isotopic measurements of other gas species (e.g. CO2, N2, O2).

Within the last decade, applications of compound-specific stable isotope analysis of nitrogen (δWe examined the relative effect of three normalization procedures, (1) internal reference calibration, (2) compound-specific calibration, and (3) scale-normalization, on the accuracy and precision of δThe overall accuracy and precision of δ

Stable isotope analysis (SIA) has proven to be a useful tool in reconstructing diets, characterizing trophic relationships, elucidating patterns of resource allocation, and constructing food webs. Consequently, the number of studies using SIA in trophic ecology has increased exponentially over the past decade. Several subdisciplines have developed, including isotope mixing models, incorporation dynamics models, lipid-extraction and correction methods, isotopic routing models, and compound-specific isotopic analysis. As with all tools, there are limitations to SIA. Chief among these are multiple sources of variation in isotopic signatures, unequal taxonomic and ecosystem coverage, over-reliance on literature values for key parameters, lack of canonical models, untested or unrealistic assumptions, low predictive power, and a paucity of experimental studies. We anticipate progress in SIA resulting from standardization of methods and models, calibration of model parameters through experimentation, and continued development of several recent approaches such as isotopic routing models and compound-specific isotopic analysis.

Pyrogenic organic matter (PyOM), the incomplete combustion product of organic materials, is considered stable in soils and represents a potentially important terrestrial sink for atmospheric carbon dioxide. One well-established method of measuring PyOM in the environment is as benzene polycarboxylic acids (BPCAs), a compound-specific method, which allows both qualitative and quantitative estimation of PyOM. Until now, stable isotope measurement of PyOM carbon involved measurement of the trimethylsilyl (TMS) or methyl (Me) polycarboxylic acid derivatives by gas chromatography–combustion–isotope ratio mass spectrometry (GC-C-IRMS). However, BPCA derivatives can contain as much as 150% derivative carbon, necessitating post-analysis correction for the accurate measurement of δ13 C values, leading to increased measurement error. Here, we describe a method for δ13 C isotope ratio measurement and quantification of BPCAs from soil-derived PyOM, based on ion-exchange chromatography (IEC-IRMS). The reproducibility of the δ13 C measurement of individual BPCAs by IEC-IRMS was better than 0.35‰ (1σ). The δ13 C-BPCA analysis of PyOM in soils, including at natural and artificially enriched 13 C-abundance, produced accurate and precise δ13 C measurements. Analysis of samples that differed in δ13 C by as much as 900‰ revealed carryover of

The hybridization of plants can have significant consequences for the structure of consumer communities, and hybridization effects on plant defenses have been suggested to affect the distribution of consumers within hybrid zones. It is currently unknown how hybridization may affect ontogenetic patterns of phenolic biosynthesis. We describe the seasonal variation of absolute and relative concentrations of 18 individual phenolics, total proanthocyanidins, and nitrogen in the Quercus \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $...

Parent-hybrid asymmetries in the biosynthesis of defense chemistry are believed to affect the distribution of herbivorous insects within plant hybrid zones. While tannins are often produced as complex, dynamic mixtures, the ecological effects of biological and ontogenetic variation in tannin metabolism within hybrid zones are poorly understood. Here, we examine correlations between the seasonal variation of absolute and relative concentrations of individual ellagitannins and total proanthocyanidins in the Quercus gambelii × Q. grisea hybrid complex and a community of leaf-mining Lepidoptera (Gracillariidae, Heliozelidae, Nepticulidae, Tischeriidae), and examine the interactive effects between tannins on leaf-miner abundance. We found strong seasonal variation in oak tannin phenotypes, but two general phenotypes are characteristic of oaks of the Q. gambelii × Q. grisea complex, based upon biosynthetic variation in high molecular weight ellagitannins. Leaf-miner community structure was significantly correlated with the dominant tannin phenotypes in the Q. gambelii × Q. grisea hybrid zone in mid-summer (July, August). Additionally, leaf-miner density was significantly negatively correlated with the ratio of vescalagin-derivatives and total proanthocyanidins in August and September. Overall, hybridization affects biological and ontogenetic variation in ellagitannin and proanthocyanidin biosynthesis within the Q. gambelii × Q. grisea hybrid complex and this variation correlates with herbivore distribution and abundance. Future studies of phenolic chemistry in plant-herbivore interactions in hybrid zones should include a more rigorous quantification of tannin phenotypes as complex, temporally dynamic mixtures.

The present paper aims to evaluate the carbon isotopic fractionation of phthalate esters (PAEs) during transport in an sandy aquifer. Breakthrough curves of di-methyl phthalate (DMP), di-ethyl phthalate (DEP), and di-n-butyl phthalate (DBP) in mixed solution were determined by miscible displacement experiment, and simulated using HYDRUS-1D software. The stable carbon isotopes (δ(13)C) of 3 PAEs in effluent were analyzed at different times. Results showed that, in the transport process in sandy sediment, PAEs are mainly trapped into the pore space instead of being adsorbed on the surface of particles. At the initial stage of transport, PAEs with lighter carbon tend to run faster in the sandy sediment, and PAEs with heavier carbon run after. However, there is no priority for the transport of PAEs with different carbon isotopes at Stage Ⅱ with mainly time-limited sorption. So the transport-based isotope fractionation occurs in the front area of contaminant plume. This effect may be relevant for interpreting carbon isotope signatures in the real contaminant site.

Conceptual models of terrestrial trophic dynamics have emphasized the potential influence of various abiotic factors, though empirical studies have found generalities to be scarce. Progress may result through an increased use of experimental gradients in tandem with existing, natural gradients of abiotic factors that are more difficult to manipulate. Along an elevation/climatic gradient, a fertilization experiment was conducted to examine the impact of environmentally induced variation in foliar nitrogen on tri-trophic interactions for Phyllonorycter sp., a leaf-miner (Lepidoptera: Gracillariidae), in Rocky Mountain white oak, Quercus gambelii. Microclimate determined the relative effect of host-plant and natural-enemy effects for Phyllonorycter sp. Cooler, more humid microclimates resulted in a higher biomass payoff (total biomass/density). Further, increased seasonal variation in foliar nitrogen content at warmer, drier sites significantly increased parasitism rates. Fertilization treatments increased foliar nitrogen content and resulted in increased early-instar mortality. Fertilization treatment also acted in a non-linear fashion with microclimate to influence spatial patterns in parasitism rates. Overall, microclimate was found to affect characteristics of each trophic level, including host-plant nitrogen dynamics, Phyllonorycter sp. performance, and parasitism rates. Additionally, nutrient availability altered patterns of parasitoid-related mortality in Phyllonorycter sp. within microclimates. These results suggest that local topographic variation in combinations of abiotic factors, or abiotic mosaics, has important effects for spatial patterns of tri-trophic interactions.

Environmental gradients are expected to alter the relative effects of host-plants and natural enemies on phytophagous insects. Moreover, studies of gradients may assist in an identification of the factors important to the outcomes of trophic interactions. We investigated the role of elevation-based variation in environmental conditions (temperature and relative humidity) and foliar nitrogen on tri-trophic interactions in Quercus gambelii Nutt. (Fagaceae) during 2001 and 2002. Quercus gambelii displayed significant elevational and seasonal fluctuation in foliar nitrogen content, and sites with similar environmental conditions produced similar foliar quality. However, leaf-miners, Phyllonorycter spec. (Lepidoptera: Gracillariidae) and Cameraria spec. (Lepidoptera: Gracillariidae), did not perform better on trees with a greater nitrogen content. Overall densities of both species declined significantly in 2002, most likely due to severe drought conditions in the south-western USA. Both species exhibited significant, but distinct, patterns in emergence rate with elevation. While environmentally based fluctuation in foliar nitrogen failed to predict the result of trophic interactions, site environmental conditions, as measured by temperature and relative humidity, were strongly related to differences in leaf-miner performance and mortality. The ordination of sites by variation in environmental conditions accurately predicts the relative effect of unexplained vs. natural-enemy sources of mortality for leaf-miners.

Arbuscular mycorrhizal (AM) fungal infection was assessed for dominant Chihuahuan Desert annual and perennial plant species. Annuals were determined to have significantly less AM infection than their perennial counterparts. Additionally, annuals were shown to have significantly smaller fine root diameters than perennials. Within 15 of the 17 species examined, the presence of AM hyphae in a root segment was not a significant determinant of root diameter, indicating than in most plant species mycorrhizal infection is not directly promoting root diameter increases. The results of this survey show that the dominant plant species of the Chihuahuan Desert group into two categories: (i) short-lived annuals with thin roots and low AM dependency, (ii) longer-lived perennials with thick mycorrhizal roots.

Stable (15)N isotopes have been used to examine movement of nitrogen (N) through various pools of the global N cycle. A central reaction in the cycle involves the reduction of nitrate (NO(-) 3) to nitrite (NO(-) 2) catalyzed by nitrate reductase (NR). Discrimination against (15)N by NR is a major determinant of isotopic differences among N pools. Here, we measured in vitro (15)N discrimination by several NRs purified from plants, fungi, and a bacterium to determine the intrinsic (15)N discrimination by the enzyme and to evaluate the validity of measurements made using (15)N-enriched NO(-) 3. Observed NR isotope discrimination ranged from 22 to 32‰ (kinetic isotope effects of 1.022-1.032) among the different isozymes at natural abundance (15)N (0.37%). As the fractional (15)N content of substrate NO(-) 3 increased from natural abundance, the product (15)N fraction deviated significantly from that expected based on substrate enrichment and (15)N discrimination measured at natural abundance. Additionally, isotopic discrimination by denitrifying bacteria used to reduce NO(-) 3 and NO(-) 2 in some protocols became a greater source of error as (15)N enrichment increased. We briefly discuss potential causes of the experimental artifacts with enriched (15)N and recommend against the use of highly enriched (15)N tracers to study N discrimination in plants or soils.

Compound-specific stable isotope analysis of amino acids has proven informative to many ecological systems, but only a handful of analytical methods are routinely employed. We evaluated a simple, rapid procedure in which biological samples undergo short-duration acid hydrolysis and the resulting amino acids are derivatized with methyl chloroformate for gas chromatography/combustion/isotope-ratio mass spectrometry (GC/C/IRMS).Amino acid derivatives were separated on a polar gas chromatography column, combusted, and δ(13)C and δ(15)N values were measured. Tests of reproducibility and accuracy were conducted for amino acid reference mixtures and biological samples. A brief case study of turtles was used to assess whether isotopic data were consistent with a priori ecological expectations.The methyl chloroformate based reaction successfully converted 15 amino acids from acid hydrolysates of biological materials into separable derivatives. The δ(13)C and δ(15)N values had high average measurement precision (σ1‰). Reference materials were measured accurately, with good agreement between EA/IRMS and GC/C/IRMS determinations. Analysis of turtle blood samples yielded data consistent with their trophic ecology.This derivatization method is a rapid means of determining carbon and nitrogen isotopic ratios of amino acids present in the biological materials often sampled for ecological studies. While amino acids with charged or polar side chains do not have uniformly high recoveries, the average precision of measurements is comparable with that of other, more established methods. Batches of samples may be prepared from many raw materials in less than a day, representing a significant reduction in preparation time over prevailing methods.

Galling arthropod communities have long been a model system for community ecologists, yet much remains to be explored concerning trophic interactions between hosts, herbivores, and natural enemies. While the utilization of stable isotope ratios can help to elucidate complex trophic interactions in such communities, estimates of trophic shift between community members are required before stable isotope analyses can be appropriately employed. In this chapter, we document the degree of trophic shift in carbon (δ 13C) and nitrogen (δ15N) isotopes within galls and hosts of a cynipid gall wasp (Cynipidae) in Quercus turbinella (Fagaceae), and a gall midge (Cecidomyiidae) and sawfly (Tenthredinidae) on Salix exigua (Salicaceae). We found trophic shift in nitrogen isotopes to be reduced relative to estimates from other systems, while carbon isotopes were considerably enriched. In combination with our current results, we review estimates of trophic shift in gall communities and compare patterns of trophic shift across studies. We discuss physiological mechanisms that determine the distribution of stable isotopes throughout gall communities and their potential effect on estimates of trophic shift (δ13C and δ15N).