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Resolving the spatial and temporal dynamics of gross primary productivity (GPP) of terrestrial ecosystems across different scales remains a challenge. Remote sensing is regarded as the solution to upscale point observations conducted at the ecosystem level, using the eddy covariance (EC) technique, to the landscape and global levels. In addition to traditional vegetation indices, the photochemical reflectance index (PRI) and the emission of solarinduced chlorophyll fluorescence (SIF), now measurable from space, provide a new range of opportunities to monitor the global carbon cycle using remote sensing. However, the scale mismatch between EC observations and the much coarser satellite-derived data complicate the integration of the two sources of data. The solution is to establish a network of in situ spectral measurements that can act as a bridge between EC measurements and remote-sensing data. In situ spectral measurements have already been conducted for many years at EC sites, but using variable instrumentation, setups, and measurement standards. In Europe in particular, in situ spectral measurements remain highly heterogeneous. The goal of EUROSPEC Cost Action ES0930 was to promote the development of common measuring protocols and new instruments towards establishing best practices and standardization of these measurements. In this review we describe the background and main tradeoffs of in situ spectral measurements, review the main results of EUROSPEC Cost Action, and discuss the future challenges and opportunities of in situ spectral measurements for improved estimation of local and global estimates of GPP over terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

In this paper we explore the skill of hyperspectral reflectance measurements and vegetation indices (VIs) derived from these in estimating carbon dioxide (CO2) fluxes of grasslands. Hyperspectral reflectance data, CO2 fluxes and biophysical parameters were measured at three grassland sites located in European mountain regions using standardized protocols. The relationships between CO2 fluxes, ecophysiological variables, traditional VIs and VIs derived using all two-band combinations of wavelengths available from the whole hyperspectral data space were analysed.We found that VIs derived from hyperspectral data generally explained a large fraction of the variability in the investigated dependent variables but differed in their ability to estimate midday and daily average CO2 fluxes and various derived ecophysiological parameters. Relationships between VIs and CO2 fluxes and ecophysiological parameters were site-specific, likely due to differences in soils, vegetation parameters and environmental conditions. Chlorophyll and water-content-related VIs explained the largest fraction of variability in most of the dependent variables. Band selection based on a combination of a genetic algorithm with random forests (GA-rF) confirmed that it is difficult to select a universal band region suitable across the investigated ecosystems. Our findings have major implications for upscaling terrestrial CO2 fluxes to larger regions and for remote- and proximal-sensing sampling and analysis strategies and call for more cross-site synthesis studies linking ground-based spectral reflectance with ecosystem-scale CO2 fluxes. [ABSTRACT FROM AUTHOR]

The study investigates the potential of a commercially available proximal sensing system -- based on a 16-band multispectral sensor -- for monitoring mean midday gross ecosystem production (GEPm) in a subalpine grassland of the Italian Alps equipped with an eddy covariance flux tower. Reflectance observations were collected for 5 consecutive years, characterized by different climatic conditions, together with turbulent carbon dioxide fluxes and their meteorological drivers. Different models based on linear regression (vegetation indices approach) and on multiple regression (reflectance approach) were tested to estimate GEPm from optical data. The overall performance of this relatively low-cost system was positive. Chlorophyll-related indices including the red-edge part of the spectrum in their formulation (red-edge normalized difference vegetation index, NDVIred-edge; chlorophyll index, CIred-edge) were the best predictors of GEPm, explaining most of its variability during the observation period. The use of the reflectance approach did not lead to considerably improved results in estimating GEPm: the adjusted R² (adj R²) of the model based on linear regression -- including all the 5 years -- was 0.74, while the adj R² for the multiple regression model was 0.79. Incorporating mean midday photosynthetically active radiation (PARm) into the model resulted in a general decrease in the accuracy of estimates, highlighting the complexity of the GEPm response to incident radiation. In fact, significantly higher photosynthesis rates were observed under diffuse as regards direct radiation conditions. The models which were observed to perform best were then used to test the potential of optical data for GEPm gap filling. Artificial gaps of three different lengths (1,3 and 5 observation days) were introduced in the GEPm time series. The values of adj R² for the three gap-filling scenarios showed that the accuracy of the gap filling slightly decreased with gap length. However, on average, the GEPm gaps were filled with an accuracy of 73 % with the model fed with NDVIred-edge, and of 76 % with the model using reflectance at 681, 720 and 781 nm and PARm data. [ABSTRACT FROM AUTHOR]

In situ synthetized silver-photocurable epoxy resin nanocomposites were analyzed by dielectric spectroscopy to study the local dynamics at temperatures well below the glass-transition temperature and the effect of silver nanoparticles on them. Two secondary processes, β and γ, were detected both for the neat matrix and nanocomposites. Relaxation times of the β secondary relaxation, obtained by fitting to Havriliak-Negami equation, were lower in the nanocomposites, as well as the activation energies calculated from the Arrhenius temperature dependence of relaxation times, due to the plasticization effect of the trapped solvent. The electric modulus formalism was used to detect the interfacial or MWS polarization, present both in the neat matrix and in the nanocomposites due to heterogeneities and interfaces. The activation energy of this relaxation increased with nanoparticle content, thus indicating an increase of the heterogeneities due to the nanoparticles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

In remote sensing, the reflectance of vegetation has been successfully used for the assessment of grassland biophysical parameters for decades. Several studies have shown that vegetation indices that are based on narrow spectral bands significantly improve the prediction of vegetation biophysical characteristics. In this work, we analyse the relationships between the biophysical parameters of grasslands and the high-spatial-resolution hyperspectral reflectance values obtained from helicopter platform data using both a spectral vegetation index and a regression approach. The regression approach was favoured as it had optimal results with respect to producing higher R2 values than the spectral index approach (water content, 0.91 v. 0.90; leaf-area index, 0.88 v. 0.61; and green ratio, 0.90 v. 0.83). These three parameters were selected to obtain a fire risk map for the Bosco della Fontana grassland areas. The extreme spatial variability of the fire risk confirmed the hypotheses regarding the importance of obtaining scale-appropriate biophysical maps to model fire risk in fragmented landscapes and ecosystems. More studies are needed in order to investigate both the limits and the opportunities of high-spatial-resolution sensors in highly fragmented landscapes for the remote detection of fire risk and to generalise the obtained results to other grassland vegetation types. [ABSTRACT FROM AUTHOR]

Proximal and remote sensing measurements were used to calculate different vegetation indices that were applied as predictors of gross primary production (GPP), total ecosystem respiration (TER), net ecosystem production (NEP) and leaf area index (LAI). Reflectance data and carbon fluxes were collected during the 2005 growing season at a mountain grassland site in the Italian Alps. Significant relationships were found between GPP, TER, NEP, LAI and the most commonly used spectral vegetation indices, the Normalized Difference Vegetation Index (NDVI) and Green-NDVI. Saturation of the spectral indices was evident in the estimation of both biophysical and ecophysiological parameters. Among the different indices, Green-NDVI was less affected by saturation on both a spatial and a temporal basis. Therefore, the use of an additional green-band sensor for spectral measurements at eddy covariance grassland sites is recommended. Concerning the bandwidth for the calculation of the indices, the highest predictive capacities among the sensor simulations included in the analysis were those of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the high-resolution hyperspectral instrument Hyperion, indicating the advantage of narrow bands for the prediction of plant parameters. Further analyses are, however, required to investigate the relationships between NEP, GPP and vegetation indices retrieved from satellite platforms, using the bands available on MODIS and Hyperion sensors. [ABSTRACT FROM AUTHOR]

In this study, the suitability of spectral vegetation indexes for predicting green ratio (the percentage of green biomass with respect to the total phytomass) has been tested with the Italian Alps and New Zealand South Island grasslands. Considering three different datasets, green ratio (GR) was found to be negatively correlated with visible bands, while it was positively correlated in the NIR region (in total, R>0.80 in the 745-950 nm interval). GR proved to be more predictable than biomass and phytomass, both using hyperspectral single narrow bands and band ratios. Considering three different datasets, GR-index correlations were found to be linear and did not involve saturation problems. Many vegetation indices have been tested; they were well correlated with GR. Green Normalized Difference Vegetation Index (NDVIgreen) was the most stable index, with high values of R2 in all areas, low standard deviation and without significant differences in the slopes and intercepts of the linear correlations of the three datasets. [ABSTRACT FROM AUTHOR]

European mountain grasslands are increasingly affected by land-use changes and climate, which have been suggested to exert important controls on grassland carbon (C) and nitrogen (N) pools. However, so far there has been no synthetic study on whether and how land-use changes and climate interactively affect the partitioning of these pools amongst the different grassland compartments. We analyzed the partitioning of C and N pools of 36 European mountain grasslands differing in land-use and climate with respect to above- and belowground phytomass, litter and topsoil (top 23 cm). We found that a reduction of management intensity and the abandonment of hay meadows and pastures increased above-ground phytomass, root mass and litter as well as their respective C and N pools, concurrently decreasing the fractional contribution of the topsoil to the total organic carbon pool. These changes were strongly driven by the cessation of cutting and grazing, a shift in plant functional groups and a related reduction in litter quality. Across all grasslands studied, variation in the impact of land management on the topsoil N pool and C/N-ratio were mainly explained by soil clay content combined with pH. Across the grasslands, below-ground phytomass as well as phytomass- and litter C concentrations were inversely related to the mean annual temperature; furthermore, C/N-ratios of phytomass and litter increased with decreasing mean annual precipitation. Within the topsoil compartment, C concentrations decreased from colder to warmer sites, and increased with increasing precipitation. Climate generally influenced effects of land use on C and N pools mainly through mean annual temperature and less through mean annual precipitation. We conclude that site-specific conditions need to be considered for understanding the effects of land use and of current and future climate changes on grassland C and N pools., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

The photosynthetic, optical, and morphological characteristics of a chlorophyll-deficient (Chl-deficient) "yellow" soybean mutant (MinnGold) were examined in comparison with 2 green varieties (MN0095 and Eiko). Despite the large difference in Chl content, similar leaf photosynthesis rates were maintained in the Chl-deficient mutant by offsetting the reduced absorption of red photons by a small increase in photochemical efficiency and lower non-photochemical quenching. When grown in the field, at full canopy cover, the mutants reflected a significantly larger proportion of incoming shortwave radiation, but the total canopy light absorption was only slightly reduced, most likely due to a deeper penetration of light into the canopy space. As a consequence, canopy-scale gross primary production and ecosystem respiration were comparable between the Chl-deficient mutant and the green variety. However, total biomass production was lower in the mutant, which indicates that processes other than steady state photosynthesis caused a reduction in biomass accumulation over time. Analysis of non-photochemical quenching relaxation and gas exchange in Chl-deficient and green leaves after transitions from high to low light conditions suggested that dynamic photosynthesis might be responsible for the reduced biomass production in the Chl-deficient mutant under field conditions., (© 2018 John Wiley & Sons Ltd.)

Proximal sensing is fundamental to monitor the spatial and seasonal dynamics of ecosystems and can be considered as a crucial validation tool to upscale in situ observations to the satellite level. Linking hyperspectral remote sensing with carbon fluxes and biophysical parameters is critical to allow the exploitation of spatial and temporal extensive information for validating model simulations at different scales. In this study, we present the WhiteRef, a new hyperspectral system designed as a direct result of the needs identified during the EUROSPEC ES0903 Cost Action, and developed by Fondazione Edmund Mach and the Institute of Biometeorology, CNR, Italy. The system is based on the ASD FieldSpec Pro spectroradiometer and was designed to acquire continuous radiometric measurements at the Eddy Covariance (EC) towers and to fill a gap in the scientific community: in fact, no system for continuous spectral measurements in the Short Wave Infrared was tested before at the EC sites. The paper illustrates the functioning of the WhiteRef and describes its main advantages and disadvantages. The WhiteRef system, being based on a robust and high quality commercially available instrument, has a clear potential for unattended continuous measurements aiming at the validation of satellites' vegetation products.

Unlabelled: Fibrolamellar hepatocellular carcinoma (FLC) is a rare subtype of liver cancer occurring mostly in children and young adults. We have shown that FLC comprises two separate entities: pure (p-FLC) and mixed-FLC (m-FLC), differing in clinical presentation and course. We show that p-FLCs have a distinct gene expression signature different from that of m-FLCs, which have a signature similar to that of classical hepatocellular carcinomas. We found p-FLC profiles to be unique among 263 profiles related to diverse tumoral and nontumoral liver samples. We identified two distinct molecular subgroups of p-FLCs with different outcomes. Pathway analysis of p-FLCs revealed ERBB2 overexpression and an up-regulation of glycolysis, possibly leading to compensatory mitochondrial hyperplasia and oncocytic differentiation. Four of the sixteen genes most significantly overexpressed in p-FLCs were neuroendocrine genes: prohormone convertase 1 (PCSK1); neurotensin; delta/notch-like EGF repeat containing; and calcitonin. PCSK1 overexpression was validated by immunohistochemistry, yielding specific, diffuse staining of the protein throughout the cytoplasm, possibly corresponding to a functional form of this convertase., Conclusion: p-FLCs have a unique transcriptomic signature characterized by the strong expression of specific neuroendocrine genes, suggesting that these tumors may have a cellular origin different from that of HCC. Our data have implications for the use of genomic profiling for diagnosis and selection of targeted therapies in patients with p-FLC., (© 2014 by the American Association for the Study of Liver Diseases.)

We describe the results of an experiment designed to compare the radiometric performance of four different spectroradiometers in ideal field conditions. A carefully designed experiment where instruments were simultaneously triggered was used to measure the Hemispherical Conical Reflectance Factors (HCRF) of four targets of varying reflectance. The experiment was in two parts. Stage 1 covered a 2 hour period finishing at solar noon, where 50 measurements of the targets were collected in sequence. Stage 2 comprised 10 rapid sequential measurements over each target. We applied a method for normalising full width half maximum (FWHM) differences between the instruments, which was a source of variability in the raw data. The work allowed us to determine data reproducibility, and we found that lower-cost instruments (Ocean Optics and PP Systems) produced data of similar radiometric quality to those manufactured by Analytical Spectral Devices (ASD -here we used the ASD FieldSpec Pro) in the spectral range 400-850 nm, which is the most significant region for research communities interested in measuring vegetation dynamics. Over the longer time-series there were changes in HCRF caused by the structural and spectral characteristics of some targets.

Background: Colon cancer (CC) pathological staging fails to accurately predict recurrence, and to date, no gene expression signature has proven reliable for prognosis stratification in clinical practice, perhaps because CC is a heterogeneous disease. The aim of this study was to establish a comprehensive molecular classification of CC based on mRNA expression profile analyses., Methods and Findings: Fresh-frozen primary tumor samples from a large multicenter cohort of 750 patients with stage I to IV CC who underwent surgery between 1987 and 2007 in seven centers were characterized for common DNA alterations, including BRAF, KRAS, and TP53 mutations, CpG island methylator phenotype, mismatch repair status, and chromosomal instability status, and were screened with whole genome and transcriptome arrays. 566 samples fulfilled RNA quality requirements. Unsupervised consensus hierarchical clustering applied to gene expression data from a discovery subset of 443 CC samples identified six molecular subtypes. These subtypes were associated with distinct clinicopathological characteristics, molecular alterations, specific enrichments of supervised gene expression signatures (stem cell phenotype-like, normal-like, serrated CC phenotype-like), and deregulated signaling pathways. Based on their main biological characteristics, we distinguished a deficient mismatch repair subtype, a KRAS mutant subtype, a cancer stem cell subtype, and three chromosomal instability subtypes, including one associated with down-regulated immune pathways, one with up-regulation of the Wnt pathway, and one displaying a normal-like gene expression profile. The classification was validated in the remaining 123 samples plus an independent set of 1,058 CC samples, including eight public datasets. Furthermore, prognosis was analyzed in the subset of stage II-III CC samples. The subtypes C4 and C6, but not the subtypes C1, C2, C3, and C5, were independently associated with shorter relapse-free survival, even after adjusting for age, sex, stage, and the emerging prognostic classifier Oncotype DX Colon Cancer Assay recurrence score (hazard ratio 1.5, 95% CI 1.1-2.1, p = 0.0097). However, a limitation of this study is that information on tumor grade and number of nodes examined was not available., Conclusions: We describe the first, to our knowledge, robust transcriptome-based classification of CC that improves the current disease stratification based on clinicopathological variables and common DNA markers. The biological relevance of these subtypes is illustrated by significant differences in prognosis. This analysis provides possibilities for improving prognostic models and therapeutic strategies. In conclusion, we report a new classification of CC into six molecular subtypes that arise through distinct biological pathways.

Context: Pheochromocytoma and paraganglioma are rare neural-crest-derived tumors. They are metastatic in 15% of cases, and the identification of a germline mutation in the SDHB gene is a predictive risk factor for malignancy and poor prognosis. To date, the link between SDHB mutations and malignancy is still missing., Objective: Epithelial to mesenchymal transition (EMT) is a developmental event, reactivated in cancer cells to promote cell mobility and invasiveness. The aim of this study was to address the participation of EMT in the metastatic evolution of pheochromocytoma/paraganglioma., Design and Patients: Transcriptomic profiling of EMT was performed on 188 tumor samples, using a set of 94 genes implicated in this pathway. Activation of EMT was further confirmed at protein level by immunohistochemistry in a second set of 93 tumors., Results: Hierarchical unsupervised classification showed that most SDHB-metastatic samples clustered together, indicating that EMT is differently regulated in these tumors. Major actors of EMT, metalloproteases and components of cellular junctions, were either up-regulated (LOXL2, TWIST, TCF3, MMP2, and MMP1) or down-regulated (KRT19 and CDH2) in SDHB-metastatic tumors compared with nonmetastatic ones. Interestingly, within metastatic tumors, most of these genes (LOXL2, TWIST, TCF3, MMP2, and KRT19) also allowed us to discriminate SDHB-mutated from non-SDHB-related tumors. In the second set of tumors, we studied Snail1/2 expression by immunohistochemistry and observed its specific nuclear translocation in all SDHB-metastatic tumors., Conclusion: We have identified the first pathway that distinguishes SDHB-metastatic from all other types of pheochromocytomas/paragangliomas and suggest that activation of the EMT process might play a critical role in the particularly invasive phenotype of this group of tumors.

This article examines the possibility of exploiting ground reflectance in the near-infrared (NIR) for monitoring grassland phytomass on a temporal basis. Three new spectral vegetation indices (infrared slope index, ISI; normalized infrared difference index, NIDI; and normalized difference structural index, NDSI), which are based on the reflectance values in the H25 (863-881 nm) and the H18 (745-751 nm) Chris Proba (mode 5) bands, are proposed. Ground measurements of hyperspectral reflectance and phytomass were made at six grassland sites in the Italian and Austrian mountains using a hand-held spectroradiometer. At full canopy cover, strong saturation was observed for many traditional vegetation indices (normalized difference vegetation index (NDVI), modified simple ratio (MSR), enhanced vegetation index (EVI), enhanced vegetation index 2 (EVI 2), renormalized difference vegetation index (RDVI), wide dynamic range vegetation index (WDRVI)). Conversely, ISI and NDSI were linearly related to grassland phytomass with negligible inter-annual variability. The relationships between both ISI and NDSI and phytomass were however site specific. The WinSail model indicated that this was mostly due to grassland species composition and background reflectance. Further studies are needed to confirm the usefulness of these indices (e.g. using multispectral specific sensors) for monitoring vegetation structural biophysical variables in other ecosystem types and to test these relationships with aircraft and satellite sensors data. For grassland ecosystems, we conclude that ISI and NDSI hold great promise for non-destructively monitoring the temporal variability of grassland phytomass.

Pheochromocytomas and paragangliomas are neuroendocrine tumors that occur in the context of inherited cancer syndromes in ∼30% of cases and are linked to germline mutations in the VHL, RET, NF1, SDHA, SDHB, SDHC, SDHD, SDHAF2 and TMEM127 genes. Although genome-wide expression studies have revealed some of the mechanisms likely to be involved in pheochromocytoma/paraganglioma tumorigenesis, the complete molecular distinction of all subtypes of hereditary tumors has not been solved and the genetic events involved in the generation of sporadic tumors are unknown. With these purposes in mind, we investigated 202 pheochromocytomas/paragangliomas, including 75 hereditary tumors, using expression profiling, BAC array comparative genomic hybridization and somatic mutation screening. Gene expression signatures defined the hereditary tumors according to their genotype and notably, led to a complete subseparation between SDHx- and VHL-related tumors. In tumor tissues, the systematic characterization of somatic genetic events associated with germline mutations in tumor suppressor genes revealed loss of heterozygosity (LOH) in a majority of cases, but also detected point mutations and copy-neutral LOH. Finally, guided by transcriptome classifications and LOH profiles, somatic mutations in VHL or RET genes were identified in 14% of sporadic pheochromocytomas/paragangliomas. Overall, we found a germline or somatic genetic alteration in 45.5% (92/202) of the tumors in this large series of pheochromocytomas/paragangliomas. Regarding mutated genes, specific molecular pathways involved in tumorigenesis mechanisms are identified. Altogether, these new findings suggest that somatic mutation analysis is likely to yield important clues for personalizing molecular targeted therapies.

This paper reviews the currently available optical sensors, their limitations and opportunities for deployment at Eddy Covariance (EC) sites in Europe. This review is based on the results obtained from an online survey designed and disseminated by the Co-cooperation in Science and Technology (COST) Action ESO903-"Spectral Sampling Tools for Vegetation Biophysical Parameters and Flux Measurements in Europe" that provided a complete view on spectral sampling activities carried out within the different research teams in European countries. The results have highlighted that a wide variety of optical sensors are in use at flux sites across Europe, and responses further demonstrated that users were not always fully aware of the key issues underpinning repeatability and the reproducibility of their spectral measurements. The key findings of this survey point towards the need for greater awareness of the need for standardisation and development of a common protocol of optical sampling at the European EC sites.

Mitochondrial succinate-coenzyme Q reductase (complex II) consists of four subunits, SDHA, SDHB, SDHC and SDHD. Heterozygous germline mutations in SDHB, SDHC, SDHD and SDHAF2 [encoding for succinate dehydrogenase (SDH) complex assembly factor 2] cause hereditary paragangliomas and pheochromocytomas. Surprisingly, no genetic link between SDHA and paraganglioma/pheochromocytoma syndrome has ever been established. We identified a heterozygous germline SDHA mutation, p.Arg589Trp, in a woman suffering from catecholamine-secreting abdominal paraganglioma. The functionality of the SDHA mutant was assessed by studying SDHA, SDHB, HIF-1alpha and CD34 protein expression using immunohistochemistry and by examining the effect of the mutation in a yeast model. Microarray analyses were performed to study gene expression involved in energy metabolism and hypoxic pathways. We also investigated 202 paragangliomas or pheochromocytomas for loss of heterozygosity (LOH) at the SDHA, SDHB, SDHC and SDHD loci by BAC array comparative genomic hybridization. In vivo and in vitro functional studies demonstrated that the SDHA mutation causes a loss of SDH enzymatic activity in tumor tissue and in the yeast model. Immunohistochemistry and transcriptome analyses established that the SDHA mutation causes pseudo-hypoxia, which leads to a subsequent increase in angiogenesis, as other SDHx gene mutations. LOH was detected at the SDHA locus in the patient's tumor but was present in only 4.5% of a large series of paragangliomas and pheochromocytomas. The SDHA gene should be added to the list of genes encoding tricarboxylic acid cycle proteins that act as tumor suppressor genes and can now be considered as a new paraganglioma/pheochromocytoma susceptibility gene.

Desmoid tumors are fibroblastic/myofibroblastic proliferations. Previous studies reported that CTNNB1 mutations were detected in 84% and that mutations of the APC gene were found in several cases of sporadic desmoid tumors lacking CTNNB1 mutations. Forty tumors were analyzed by comparative genomic hybridization (CGH). Karyotype and fluorescence in situ hybridization revealed a nonrandom occurrence of trisomy 8 associated with an increased risk of recurrence. We report the first molecular characterization including a large series of patients. We performed array CGH on frozen samples of 194 tumors, and we screened for APC mutations in patients without CNNTB1 mutation. A high frequency of genomically normal tumors was observed. Four relevant and recurrent alterations (loss of 6q, loss of 5q, gain of 20q, and gain of Chromosome 8) were found in 40 out of 46 tumors with chromosomal changes. Gain of Chromosomes 8 and 20 was not associated with an increased risk of recurrence. Cases with loss of 5q had a minimal common region in 5q22.5 including the APC locus. Alterations of APC, including loss of the entire locus, and CTNNB1 mutation could explain the tumorigenesis in 89% of sporadic desmoids tumors and desmoids tumors occurring in the context of Gardner's syndrome. A better understanding of the pathogenetic pathways in the initiation and progression of desmoid tumors requires studies of 8q and 20q gains, as well as of 6q and 5q losses, and study of the Wnt/beta-catenin pathway., ((c) 2010 Wiley-Liss, Inc.)

The Warburg effect describes how cancer cells down-regulate their aerobic respiration and preferentially use glycolysis to generate energy. To evaluate the link between hypoxia and Warburg effect, we studied mitochondrial electron transport, angiogenesis and glycolysis in pheochromocytomas induced by germ-line mutations in VHL, RET, NF1 and SDH genes. SDH and VHL gene mutations have been shown to lead to the activation of hypoxic response, even in normoxic conditions, a process now referred to as pseudohypoxia. We observed a decrease in electron transport protein expression and activity, associated with increased angiogenesis in SDH- and VHL-related, pseudohypoxic tumors, while stimulation of glycolysis was solely observed in VHL tumors. Moreover, microarray analyses revealed that expression of genes involved in these metabolic pathways is an efficient tool for classification of pheochromocytomas in accordance with the predisposition gene mutated. Our data suggest an unexpected association between pseudohypoxia and loss of p53, which leads to a distinct Warburg effect in VHL-related pheochromocytomas.