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Strategies shrubby junipers adopt to tolerate drought differ by site

Drought-induced dieback episodes are globally reported among forest ecosystems but they have been understudied in scrublands. Chronically-stressed individuals are supposed to be more vulnerable prior to drought which triggers death. Drought-triggered dieback and mortality events affecting Mediterranean Juniperus phoenicea scrublands were analyzed in two sites with contrasting climate and soil conditions located in Spain. The radial growth patterns of coexisting living and dead junipers, including the calculation of growth statistics used as early-warning signals, quantified growth response to climate, were characterized and the wood C and O isotope discrimination was analyzed. In the inland, continental site with rocky substrates (Yaso, Huesca, N Spain), dead junipers grew less than living junipers about three decades prior to the dieback started in 2016. However, in the coastal, mild site with sandy soils (Doñana, Huelva, SW Spain), dead junipers were smaller but grew more than living junipers about two decades before the dieback onset in 2005. The only common patterns between sites were the higher growth coherence in both living and dead junipers prior to the dieback, and the decrease in growth persistence of dead junipers. Cool and wet conditions in the prior winter and current spring, and cool summer conditions enhanced juniper growth. In Doñana, growth of living individuals was more reduced by warm July conditions than in the case of dead individuals. Higher ?13C values in Yaso indicate also more pronounced drought stress. In Yaso, dead junipers presented lower ?18O values, but the opposite occurred in Doñana suggesting different changes in stomatal conductance prior to death. Warm summer conditions enhance evapotranspiration rates and trigger dieback in this shallow-rooted species, particularly in sites with a poor water-holding capacity. Chronic, slow growth is not always a reliable predictor of drought-triggered mortality. informacion[at]ebd.csic.es: Camarero et al (2020) Dieback and mortality of junipers caused by drought: Dissimilar growth and wood isotope patterns preceding shrub death. Agr Forest Meteorol 291, 108078. DOI 10.1016/j.agrformet.2020.108078


https://www.sciencedirect.com/science/article/pii/S0168192320301805?dgcid=author#ack0001
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LC-MS determination of catecholamines and related metabolites in red deer urine and hair

LC-MS determination of catecholamines and related metabolites in red deer urine and hair

A novel analytical methodology for the determination and extraction of catecholamines (dopamine, epinephrine and norepinephrine) and their metabolites DL-3,4-dihydroxyphenyl glycol and DL-3,4-dihydroxymandelic acid by LC-MS is here developed and validated for application to human and animal urine and hair samples. The method is based on the preliminary extraction of analytes by a magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) composite. This is followed by a < 9 min chromatographic separation of the target compounds in an Onyx Monolithic C18 column using a mixture of 0.01% (v/v) heptafluorobutyric acid in water and methanol at 500 µL min-1 flow rate. Detection limits within range from 0.055 to 0.093 µg mL-1, and precision values of the response and retention times of analytes were > 90%. Accuracy values comprised the range 79.5–109.5% when the analytes were extracted from deer urine samples using the selected MMWCNT-poly(STY-DVB) sorbent. This methodology was applied to real red deer urine and hair samples, the resulting concentrations within range from 0.05 to 0.5 µg mL-1for norepinephrine and from 1.0 to 44.5 µg mL-1 for its metabolite 3,4-dihydroxyphenyl glycol. Analyses of red deer hair resulted in high amounts of 3,4-dihydroxyphenyl. informacion[at]ebd.csic.es: Murtada et al (2019) LC-MS determination of catecholamines and related metabolites in red deer urine and hair extracted using magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) composite. J Chromatogr B https://doi.org/10.1016/j.jchromb.2019.121878


https://www.sciencedirect.com/science/article/abs/pii/S157002321931150X