Trophic assessment of red seabream (Pagrus major) as a possible bioindicator of human activities in the South Sea of Korea using stable C and N isotopes.

To assess the impact of sand mining on resource utilization by the red seabream (Pagrus major) and the trophic structure of fish assemblages two years after mining activities, we compared stable isotope ratios (δ13C and δ15N) and isotopic niches between aggregated mining and control sites in April and August 2022. Our results showed no spatial differences in the δ13C and δ15N values of red seabream between the sand mining and control sites, suggesting that the mining did not affect their dietary resources. Furthermore, the considerable overlap among fish consumers suggested that the fish food web in mining areas has trophic functions similar to those in natural habitats after mining activities. Overall, our study enhances our understanding of ecosystem conservation and the ecological-based management of coastal areas.

Spatial distribution, environmental behavior, and health risk assessment of PAHs in soils at prototype coking plants in Shanxi, China: Stable carbon isotope and molecular composition analyses.

To investigate the environmental behavior of and carcinogenic risk posed by 16 priority-controlled polycyclic aromatic hydrocarbons (PAHs), soil samples and air samples from the coke oven top were collected in two prototype coking plants (named PF and JD). The PF soils contained more PAHs than the JD soils because the PF plant employed the side-charging technique and had a lower coke oven height. The soils from both plants contained enough PAHs to pose a carcinogenic risk, and this risk was higher in the PF plant. Data were collected on the source characteristic spectrum of stable carbon isotopic composition (δ13C) of PAHs emitted from the coke oven top (δ13C values of -36.02‰ to -32.05‰ for gaseous PAHs and -34.09‰ to -25.28‰ for particulate PAHs), and these data fill a research gap and may be referenced for isotopic-technology-based source apportionment. Diagnostic ratios and isotopic technology revealed that the coking plant soils were mainly influenced by the coking process, followed by vehicle exhaust; the soils near the boundary of each plant were slightly affected by C3 plant burning. For most PAHs [excluding fluoranthene, benzo(k)fluoranthene, indeno(1,2,3-c,d)pyrene, and dibenzo(a,h)anthracene], the dominant migration process was the net volatilization of PAHs from soil to air. In the PF plant, 13C was depleted in gaseous PAHs during volatilization.

Using Liquid Chromatography-Isotope Ratio Mass Spectrometry for Detection of Economically Motivated Adulteration of Maple Syrup.

BACKGROUND: Maple syrup is a sought-after commodity, and used as a condiment and a sweetener. Also, it is an active target of economically motivated adulteration (EMA), similar to other foods such as lemon juice and honey. OBJECTIVE: This study is aimed to detect low cost sugar adulteration in maple syrup via an internal standard method using malic acid through solid-phase extraction (SPE) and LC with isotope ratio mass spectrometric detection (LC-IRMS). METHODS: In this work, an optimized SPE sample preparation procedure was used for the isolation of organic acids from maple syrup. Using LC-IRMS, malic acid was separated from other organic acids and the δ13C value of malic acid was determined. Eleven maple syrup samples, domestic or imported from Canada, were evaluated for 13C/12C ratios (δ13C values) using combustion module-cavity ring down spectrometry (CM-CRDS) and compared to the δ13C values obtained from well-established elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) methods. The δ13C values of isolated malic acid analyzed by SPE-LC-IRMS were used as internal standards and compared to the δ13C values of bulk maple syrup; difference (δ13Csugars - δ13Cmalic acid) values greater than 3.6‰ are indicative of low-cost sugar adulteration. RESULTS: Overall, the results obtained from SPE-LC-IRMS provided a faster, novel analysis approach for determining low-cost sugar adulteration in maple syrup for regulatory purposes. This method also provided lower detectable limits of adulteration versus current literature reports using bulk analysis and comparable detection limits to Tremblay and co-workers who utilized an internal standard method. CONCLUSION: SPE-LC-IRMS is a robust method that can be used for detecting adulteration in maple syrup samples for regulatory purposes. HIGHLIGHTS: SPE-LC-IRMS is a faster, novel analysis approach for determining C4 adulteration in maple syrup with lower detection limits.

Improved 13C metabolic flux analysis in Escherichia coli metabolism: application of a high-resolution MS (GC-EI-QTOF) for comprehensive assessment of MS/MS fragments.

Gas chromatography-tandem mass spectrometry with electron ionization (GC-EI-MS/MS) provides rich information on stable-isotope labeling for 13C-metabolic flux analysis (13C-MFA). To pave the way for the routine application of tandem MS data for metabolic flux quantification, we aimed to compile a comprehensive library of GC-EI-MS/MS fragments of tert-butyldimethylsilyl (TBDMS) derivatized proteinogenic amino acids. First, we established an analytical workflow that combines high-resolution gas chromatography-quadrupole time-of-flight mass spectrometry and fully 13C-labeled biomass to identify and structurally elucidate tandem MS amino acid fragments. Application of the high-mass accuracy MS procedure resulted into the identification of 129 validated precursor-product ion pairs of 13 amino acids with 30 fragments being accepted for 13C-MFA. The practical benefit of the novel tandem MS data was demonstrated by a proof-of-concept study, which confirmed the importance of the compiled library for high-resolution 13C-MFA. ONE SENTENCE SUMMARY: An analytical workflow that combines high-resolution mass spectrometry (MS) and fully 13C-labeled biomass to identify and structurally elucidate tandem MS amino acid fragments, which provide positional information and therefore offering significant advantages over traditional MS to improve 13C-metabolic flux analysis.

Use of carbon-13 NMR to identify known natural products by querying a nuclear magnetic resonance database-An assessment.

The quick identification of known organic low molecular weight compounds, also known as structural dereplication, is a highly important task in the chemical profiling of natural resource extracts. To that end, a method that relies on carbon-13 nuclear magnetic resonance (NMR) spectroscopy, elaborated in earlier works of the author's research group, requires the availability of a dedicated database that establishes relationships between chemical structures, biological and chemical taxonomy, and spectroscopy. The construction of such a database, called acd_lotus, was reported earlier, and its usefulness was illustrated by only three examples. This article presents the results of structure searches carried out starting from 58 carbon-13 NMR data sets recorded on compounds selected in the metabolomics section of the biological magnetic resonance bank (BMRB). Two compound retrieval methods were employed. The first one involves searching in the acd_lotus database using commercial software. The second one operates through the freely accessible web interface of the nmrshiftdb2 database, which includes the compounds present in acd_lotus and many others. The two structural dereplication methods have proved to be efficient and can be used together in a complementary way.

Machine Learning Predicts the Methane Clumped Isotopologue (12CH2D2) Distributions Constrain Biogeochemical Processes and Estimates the Potential Budget.

Methane (CH4) is a matter of environmental concern; however, global methane isotopologue data remain inadequate. This is due to the challenges posed by high-resolution testing technology and the need for larger sample volumes. Here, worldwide methane clumped isotope databases (n = 465) were compiled. We compared machine-learning (ML) models and used random forest (RF) to predict new Δ12CH2D2 distributions, which cover valuable and hard-to-replicate methane clumped isotope experimental data. Our RF model yields a reliable and continuous database including ruminants, acetoclastic methane, multiple pyrolysis, and controlled experiments. We showed the effectiveness of utilizing a new data set to quantify isotopologue fractionations in biogeochemical methane processes, as well as predicting the steady-state atmospheric methane clumped isotope composition (Δ13CH3D of +2.26 ± 0.71‰ and Δ12CH2D2 of +62.06 ± 4.42‰) with notable biological contributions. Our measured summer and winter water emitted gases (n = 6) demonstrated temperature-driven seasonal microbial community evolution determined by atmospheric clumped isotope temporal variations (Δ 13CH3D ∼ -0.91 ± 0.25 ‰ and Δ12CH2D2 ∼ +3.86 ± 0.84 ‰), which in turn is relevant for future models quantifying the contribution of methane sources and sinks. Predicting clumped isotopologues translates our methane geochemical understanding into quantifiable variables for modeling that can continue to improve predictions and potentially inform global greenhouse gas emissions and mitigation policy.

Assessment of stable carbon isotope 13С/12С ratio in phthalates from surface waters using HPLC-HRMS-TOF approach.

A method for estimating the ratio of stable carbon isotopes 13С/12С in the composition of phthalates from surface water at a trace concentration level is proposed. It is based on the concentration of hydrophobic components of water using an analytical reversed phase HPLC column followed by their gradient separation and detection of eluted phthalates using a high-resolution time-of-flight mass spectrometer (ESI-HRMS-TOF) in the form of molecular ions. The ratio of stable carbon isotopes 13С/12C in phthalates is calculated as a ratio of integrals under the monoisotopic [M+1+H]+ and [M+H]+ peaks. The Δ13C value is calculated relatively to the 13C/12C ratio in commercial DnBP and DEHP phthalates used as standards. The minimal concentration of DnBP and DEHP in water required for a reliable determination of Δ13C value is estimated by the level of ca. 0.2 µg L-1. The technique has been verified during the monitoring of priority phthalates in the waters of Lake Baikal.

Longitudinal assessment of mitochondrial dysfunction in acute traumatic brain injury using hyperpolarized [1-13 C]pyruvate.

PURPOSE: [13 C]Bicarbonate formation from hyperpolarized [1-13 C]pyruvate via pyruvate dehydrogenase, a key regulatory enzyme, represents the cerebral oxidation of pyruvate and the integrity of mitochondrial function. The present study is to characterize the chronology of cerebral mitochondrial metabolism during secondary injury associated with acute traumatic brain injury (TBI) by longitudinally monitoring [13 C]bicarbonate production from hyperpolarized [1-13 C]pyruvate in rodents. METHODS: Male Wistar rats were randomly assigned to undergo a controlled-cortical impact (CCI, n = 31) or sham surgery (n = 22). Seventeen of the CCI and 9 of the sham rats longitudinally underwent a 1 H/13 C-integrated MR protocol that includes a bolus injection of hyperpolarized [1-13 C]pyruvate at 0 (2 h), 1, 2, 5, and 10 days post-surgery. Separate CCI and sham rats were used for histological validation and enzyme assays. RESULTS: In addition to elevated lactate, we observed significantly reduced bicarbonate production in the injured site. Unlike the immediate appearance of hyperintensity on T2 -weighted MRI, the contrast of bicarbonate signals between the injured region and the contralateral brain peaked at 24 h post-injury, then fully recovered to the normal level at day 10. A subset of TBI rats demonstrated markedly increased bicarbonate in normal-appearing contralateral brain regions post-injury. CONCLUSION: This study demonstrates that aberrant mitochondrial metabolism occurring in acute TBI can be monitored by detecting [13 C]bicarbonate production from hyperpolarized [1-13 C]pyruvate, suggesting that [13 C]bicarbonate is a sensitive in-vivo biomarker of the secondary injury processes.

Chemical markers in marine food web: A simple workflow based on methyl tert-butyl ether extraction for fatty acids and stable isotopes assessment in plankton samples.

Fatty acids (FAs) are used, often in combination with stable isotopes (SIs), as chemical biomarkers to assess the contribution of different prey to the diet of consumers and define food web structure and dynamics. Extraction of lipids is traditionally carried out using methanol (MeOH) combined with chloroform or dichloromethane, these latter being well-known environmental pollutant and potential carcinogenic agents. Recently, extraction protocols based on methyl tert-butyl ether (MTBE) and MeOH have been proposed as an alternative to halogenated solvents in lipidomic studies. However, no specific investigation has been performed to assess MTBE suitability in marine ecological studies including FA analysis together with SI measurements. We used an analytical workflow for qualitative and quantitative analysis of FAs and SIs in field samples of phytoplankton, zooplankton and the scyphomedusa Pelagia noctiluca, applying MTBE in comparison with chloroform- and dichloromethane-based protocols for total lipid extraction. Our analysis suggested that MTBE is a reliable substitute for lipid extraction in trophic ecology studies in marine planktonic organisms.

The 13C-bicarbonate technique as a tool for measurement of energy expenditure in overweight dogs undergoing body weight reduction and the effect of different dietary composition.

Changes in body size and composition, i.e., body weight (BW) gain or loss, affect the daily energy expenditure (EE). To ensure an appropriate BW reduction and to find an efficient strategy to reduce and maintain a target BW, regular evaluations and adjustments of energy allowance are important. This study aimed to provide a detailed knowledge about the possible changes in resting EE using the oral 13C-bicarbonate technique (o13CBT) as a research tool in 16 overweight pet dogs undergoing BW reduction. Dietary composition (i.e., in % of dry matter [DM] being a high protein [33.3], low fat [9.6], and high crude fiber [18.0] diet [LFHFibre], and a high protein [37.9], high fat [52.0], carbohydrate-free diet [HFat]) during 16 wk of energy restriction were evaluated regarding effects on resting EE, rate of BW reduction, body composition, and plasma concentrations of metabolic hormones involved in energy metabolism and appetite regulation. The mean BW loss was higher (P < 0.05) for the dogs fed the LFHFibre diet (1.1%/wk) than that for dogs fed the HFat diet (0.8%/wk), but the total BW reduction of 14.6% and 12.0% of initial BW did not differ significantly (P > 0.05). Resting EE was lower (P < 0.02) after the BW reduction; 414 kJ (99 kcal)/kg BW0.75/d at the start (week 0) and 326 kJ (78 kcal)/kg BW0.75/d at the end (week 16) of the study. The BW reduction in both groups (P > 0.05) consisted of both fat mass (FM) and fat-free mass (FFM). Energy expenditure, calculated in relation to amount of FFM, was not significantly (P > 0.05) affected by BW reduction. Dietary composition did not significantly affect (P > 0.05) plasma concentrations of insulin, leptin, and ghrelin, and no effect (P > 0.05) of BW reduction was observed on hormone concentrations. In conclusion, the o13CBT proved to be a useful research method for studying short-term EE in overweight dogs. Even though all dogs lost BW, most dogs were still overweight at the end of the study. Due to a high individual variation among dogs, a longer experimental period with a larger sample size would be desirable.

The most common nutritional disorder in dogs is overweight, and knowledge about dogs' energy requirement is therefore important to adjust daily feed allowance. Changes in body weight may affect energy expenditure (EE) and, thereby, energy requirement. This study aimed to measure such potential changes under resting conditions in overweight dogs. It was found that the minimally invasive 13C-bicarbonate technique was a useful research method for studies regarding EE during weight loss (WL) in dogs. EE decreased when the dogs lost weight, and energy allowance needed to be reduced to maintain WL. The second objective of this study was to evaluate the effects of feeding diets with different macronutrient compositions on EE, rate of WL, body composition, and plasma concentrations of hormones involved in energy metabolism and appetite regulation. The mean WL rate was slightly higher for dogs fed a diet with high protein, low fat, and high crude fiber contents than those fed a carbohydrate-free diet with a high protein and fat contents. However, diet did not affect the resting EE, measured plasma hormone concentrations, or the total WL at the end of the study.

Quantitative assessment of selective degradation behavior of etoxazole in different classes of organisms by compound-specific isotope analysis.

In this paper, the stereoselective degradation and quantitative identification of chiral pesticide etoxazole in organisms with different classes of organisms (soil, chlorella algal fluid and mice) were carried out by compound-specific isotope analysis (CSIA). The degradation behavior and stable isotope fractionation effect of etoxazole in soil, chlorella and mice were investigated. The R-etoxazole degraded faster than S-etoxazole in different classes of organisms. The metabolites M1, M2 and M3 were detected in all three substrates. Biodegradation is the main factor for the change of stable isotope ratio of chiral pesticide etoxazole. Furthermore, the relationship between fractionation value of carbon isotope and residual concentration of etoxazole is established by Rayleigh equation, and the biodegradation rate of etoxazole could be calculated by using CSIA without measuring the concentration of etoxazole. Therefore, the use of CSIA can accurately assess the degradation behavior of pesticide pollution in the environment and provide a certain scientific evidence and technical support in the process of environmental remediation.

δ18O compound-specific stable isotope assessment: An advanced analytical strategy for sophisticated adulterations detection in essential oils - Application to spearmint, cinnamon, and bitter almond essential oils authentication.

Natural plant extracts are primarily used as raw materials in the cosmetic and perfumery industry. However, adulterations with petrochemical products are occurring in the market, leading to non-100% natural products. Several analytical techniques such as impurity detection or enantioselective ratio assessments have been previously described as good indicators to detect any addition of synthetic products, but these techniques are ineffective with novel type of synthetic pathways such as semisynthesis. In order to improve authentication, development of advanced analytical strategies such as δ18O stable isotopic ratios assessment was tested on spearmint, cinnamon and bitter almond essential oils major metabolites (carvone, (E)-cinnamaldehyde, and benzaldehyde). Natural δ18O mean values (δ18OCarvone = 18.4‰; δ18OCinnamaldehyde = 13.9‰; δ18OBenzaldehyde = 16.5‰) were found to be higher than semisynthetic origin for the 3 studied molecules (δ18OCarvone = 9.2‰; δ18OCinnamaldehyde = 8.8‰; δ18OBenzaldehyde = 10.9‰). These measurements proved to be efficient to discriminate natural and semisynthetic origins of these components and therefore potentially lead to a novel way to authenticate natural products.

Polluting characteristics, sources, cancer risk, and cellular toxicity of PAHs bound in atmospheric particulates sampled from an economic transformation demonstration area of Dongguan in the Pearl River Delta, China.

The Songshan Lake Science and Technology Industrial Park is a national economic transition demonstration area, which centers at a traditional industrial region, in Dongguan, China. We were interested in the involved atmospheric particulates-bound PAHs regarding their sources, cancer risk, and related cellular toxicity for those in other areas under comparable conditions. In this study, the daily concentrations of TSP, PM10, and PM2.5 were averaged 127.95, 95.91, and 67.62 µg/m3, and the bound PAHs were averaged 1.31, 1.22, and 0.77 ng/m3 in summer and 12.72, 20.51 and 40.27 ng/m3 in winter, respectively. The dominant PAHs were those with 5-6 rings, and 4-6 rings in summer and winter, respectively. The incremental lifetime cancer risk (ILCR) (90th percentile probability) of total PAHs was above 1.00E-06 in each age group, particularly high in adolescents. Sensitivity analysis indicated that slope factor and body weight had greater impact than exposure duration and inhalation rate on the ILCR. Moreover, treatment of human bronchial epithelial BEAS-2B cells with mixed five indicative PAHs increased the formation of ROS, DNA damage (elevation in γ-H2AX), and protein levels of CAR, PXR, CYP1A1, 1A2, 1B1, while reduced the AhR protein, with the winter mixture more potent than summer. For the sources of PAHs, the stable carbon isotope ratio analysis and diagnostic ratios consistently pointed to petroleum and fossil fuel combustion as major sources. In conclusion, our findings suggest that particulates-bound PAHs deserve serious concerns for a cancer risk in such environment, and the development of new power sources for reducing fossil fuel combustion is highly encouraged.

Archaeobotanical and isotopic analyses of waterlogged remains from the Neolithic pile-dwelling site of Zug-Riedmatt (Switzerland): Resilience strategies of a plant economy in a changing local environment.

The excellent preservation of the waterlogged botanical remains of the multiphase Neolithic pile-dwelling site of Zug-Riedmatt (Central Switzerland) yielded an ideal dataset to delve into the issue of plant economy of a community spanning several decades. The study identified a major change in crops where oil plants played a key role in the site's initial phase before being supplanted over the course of a few decades by naked wheat, barley and pea. Wild plants continued to be gathered albeit in different proportions. In the latest settlement phase, the changes in the local vegetation and in the values of the analyses of carbon stable isotopes suggest a less humid environment. The hypothesis is that the changes perceived in the plant economy represent a resilience strategy adopted by the inhabitants in reaction to short term local climatic alterations. The two types of soil sampling techniques (monolith and bulk) allowed comparing these results. While the density of plant remains appears to be underestimated among the samples collected by the monolith technique, the proportions of economic taxa remain unaffected. The findings thus reveal that when the bulk samplings are distributed carefully throughout multiphase sites and avoid mixing stratigraphical units, and if the samplings are representative of all archaeological features from a whole area, then each of the two techniques offer analogous results.

Assessment of Compound-Specific Fatty Acid δ13C and δ2H Values to Track Fish Mobility in a Small Sub-alpine Catchment.

Methods for identifying origin, movement, and foraging areas of animals are essential for understanding ecosystem connectivity, nutrient flows, and other ecological processes. Telemetric methods can provide detailed spatial coverage but are limited to a minimum body size of specimen for tagging. In recent years, stable isotopes have been increasingly used to track animal migration by linking landscape isotope patterns into movement (isoscapes). However, compared to telemetric methods, the spatial resolution of bulk stable isotopes is low. Here, we examined a novel approach by evaluating the use of compound-specific hydrogen and carbon stable isotopes of fatty acids (δ2HFA and δ13CFA) from fish liver, muscle, brain, and eye tissues for identifying site specificity in a 254 km2 sub-alpine river catchment. We analyzed 208 fish (European bullhead, rainbow trout, and brown trout) collected in 2016 and 2018 at 15 different sites. δ13CFA values of these fish tissues correlated more among each other than those of δ2HFA values. Both δ2HFA and δ13CFA values showed tissue-dependent isotopic fractionation, while fish taxa had only small effects. The highest site specificity was for δ13CDHA values, while the δ2H isotopic difference between linoleic acid and alpha-linolenic acid resulted in the highest site specificity. Using linear discrimination analysis of FA isotope values, over 90% of fish could be assigned to their location of origin; however, the accuracy dropped to about 56% when isotope data from 2016 were used to predict the sites for samples collected in 2018, suggesting temporal shifts in site specificity of δ2HFA and δ13CFA. However, the predictive power of δ2HFA and δ13CFA over this time interval was still higher than site specificity of bulk tissue isotopes for a single time point. In summary, compound-specific isotope analysis of fatty acids may become a highly effective tool for assessing fine and large-scale movement and foraging areas of animals.

Assessment of aerobic biodegradation of lower-chlorinated benzenes in contaminated groundwater using field-derived microcosms and compound-specific carbon isotope fractionation.

Biodegradation of lower chlorinated benzenes (tri-, di- and monochlorobenzene) was assessed at a coastal aquifer contaminated with multiple chlorinated aromatic hydrocarbons. Field-derived microcosms, established with groundwater from the source zone and amended with a mixture of lower chlorinated benzenes, evidenced biodegradation of monochlorobenzene (MCB) and 1,4-dichlorobenzene (1,4-DCB) in aerobic microcosms, whereas the addition of lactate in anaerobic microcosms did not enhance anaerobic reductive dechlorination. Aerobic microcosms established with groundwater from the plume consumed several doses of MCB and concomitantly degraded the three isomers of dichlorobenzene with no observable inhibitory effect. In the light of these results, we assessed the applicability of compound stable isotope analysis to monitor a potential aerobic remediation treatment of MCB and 1,4-DCB in this site. The carbon isotopic fractionation factors (ε) obtained from field-derived microcosms were -0.7‰ ± 0.1 ‰ and -1.0‰ ± 0.2 ‰ for MCB and 1,4-DCB, respectively. For 1,4-DCB, the carbon isotope fractionation during aerobic biodegradation was reported for the first time. The weak carbon isotope fractionation values for the aerobic pathway would only allow tracing of in situ degradation in aquifer parts with high extent of biodegradation. However, based on the carbon isotope effects measured in this and previous studies, relatively high carbon isotope shifts (i.e., ∆δ13C > 4.0 ‰) of MCB or 1,4-DCB in contaminated groundwater would suggest that their biodegradation is controlled by anaerobic reductive dechlorination.

Metabolic Imaging Using Hyperpolarization for Assessment of Premalignancy.

There is an unmet need for noninvasive surrogate markers that can help identify premalignant lesions across different tumor types. Here we describe the methodology and technical details of protocols employed for in vivo 13C pyruvate metabolic imaging experiments. The goal of the method described is to identify and understand metabolic changes, to enable detection of pancreatic premalignant lesions, as a proof of concept of the high sensitivity of this imaging modality.

Hyperpolarized Carbon-13 MRI for Early Response Assessment of Neoadjuvant Chemotherapy in Breast Cancer Patients.

Hyperpolarized 13C-MRI is an emerging tool for probing tissue metabolism by measuring 13C-label exchange between intravenously injected hyperpolarized [1-13C]pyruvate and endogenous tissue lactate. Here, we demonstrate that hyperpolarized 13C-MRI can be used to detect early response to neoadjuvant therapy in breast cancer. Seven patients underwent multiparametric 1H-MRI and hyperpolarized 13C-MRI before and 7-11 days after commencing treatment. An increase in the lactate-to-pyruvate ratio of approximately 20% identified three patients who, following 5-6 cycles of treatment, showed pathological complete response. This ratio correlated with gene expression of the pyruvate transporter MCT1 and lactate dehydrogenase A (LDHA), the enzyme catalyzing label exchange between pyruvate and lactate. Analysis of approximately 2,000 breast tumors showed that overexpression of LDHA and the hypoxia marker CAIX was associated with reduced relapse-free and overall survival. Hyperpolarized 13C-MRI represents a promising method for monitoring very early treatment response in breast cancer and has demonstrated prognostic potential. SIGNIFICANCE: Hyperpolarized carbon-13 MRI allows response assessment in patients with breast cancer after 7-11 days of neoadjuvant chemotherapy and outperformed state-of-the-art and research quantitative proton MRI techniques.

Carbon isotopic measurements from coastal zone protected forests in northern China: Soil carbon decomposition assessment and its influencing factors.

Panting protected forests to increase soil carbon sequestration is an effective means of reducing carbon emissions. Soil organic carbon (SOC) decomposition is one of the main indicators of soil carbon sequestration. However, SOC decomposition and its influencing factors in protected forests have not been fully characterized, especially in coastal zones. In this paper, coastal zone protected forest stands composed of Quercus acutissima Carruth (QAC), Pinus thunbergii Parl (PTP) and mixed PTP and QAC (MF) were selected as the research objects. The trends of the SOC decomposition rate were characterized by the beta (ß) value, and the influencing factors were further explored with structural equation models. The results were as follows: The SOC content decreased from leaf to litter and then to the soil profile at all sites, while the δ13C value increased. The ß value ranged from -3.12 to -5.76, with an average of -3.81. The ß value was positively correlated with the diversity and richness of soil bacteria, supporting the hypothesis that the increase in δ13C with depth was mainly caused by isotope fractionation in the process of microbial SOC decomposition. The structural equation model showed that nitrogen and the availability of nitrogen have a strong ability to explain the value of ß, which indicates that nitrogen-based edaphic variables play an important role in affecting SOC decomposition. The SOC decomposition rate in PTP was higher than that in QAC and MF. The results of this study indicate that the prediction of SOC decomposition based on the ß value is suitable for coastal zone protected forests. The incorporation of edaphic variables into global carbon cycle models may enhance the predictions of SOC dynamics in coastal zone protected forests.