פרסומים

Understanding how different plants prioritize carbon gain and drought vulnerability under a variable water supply is important for predicting which trees will maximize woody biomass production under different environmental conditions. Here, Populus balsamifera (BS, isohydric genotype), P. simonii (SI, previously uncharacterized stomatal behaviour), and their cross, P. balsamifera x simonii (BSxSI, anisohydric genotype) were studied to assess the physiological basis for biomass accumulation and water-use efficiency across a range of water availabilities. Under ample water, whole plant stomatal conductance (gs), transpiration (E), and growth rates were higher in anisohydric genotypes (SI and BSxSI) than in isohydric poplars (BS). Under drought, all genotypes regulated the leaf to stem water potential gradient via changes in gs, synchronizing leaf hydraulic conductance (Kleaf) and E: isohydric plants reduced Kleaf, gs, and E, whereas anisohydric genotypes maintained high Kleaf and E, which reduced both leaf and stem water potentials. Nevertheless, SI poplars reduced their plant hydraulic conductance (Kplant) during water stress and, unlike, BSxSI plants, recovered rapidly from drought. Low gs of the isohydric BS under drought reduced CO2 assimilation rates and biomass potential under moderate water stress. While anisohydric genotypes had the fastest growth under ample water and higher photosynthetic rates under increasing water stress, isohydric poplars had higher water-use efficiency. Overall, the results indicate three strategies for how closely related biomass species deal with water stress: survival-isohydric (BS), sensitive-anisohydric (BSxSI), and resilience-anisohydric (SI). Implications for woody biomass growth, water-use efficiency, and survival under variable environmental conditions are discussed.

This paper examines the relationship between income, pollution, and mortality in China from 1991-2012. Using first-difference models, we document a robust positive association between city-level GDP and life expectancy. We also find a negative association between city-level particulate air pollution exposure and life expectancy that is driven by elevated cardiorespiratory mortality rates. The results suggest that while China’s unprecedented economic growth over the last two decades is associated with health improvements, pollution has served as a countervailing force.

This chapter begins by outlining four theses that are elaborations of Hume’s claim that the contents of the world ‘are entirely loose and separate’. The first, core thesis is a ‘patchwork’ theory of possibilities. The others concern laws of nature, causal relations, and global supervenience. Any position which accepts the first thesis but denies at least one of the others is referred to as a ‘Half-Hearted Humean’ position. The chapter argues that, contrary to appearances, any Half-Hearted Humean position is inconsistent. The only viable options are Wholehearted Humeanism or a denial of the core Humean thesis.

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How the immune system is negatively affected by sepsis is not fully understood. In this issue of Immunity, Shalova et al. (2015) show that during human sepsis monocytes upregulate hypoxia-inducible factor-alpha (HIF1-alpha) activity and acquire an immunosuppressive phenotype while retaining anti-bacterial and wound-healing properties.

A passively Q-switched diode-pumped Tm:YLF laser with polycrystalline Cr:ZnSe as the saturable absorber is demonstrated for the first time, to the best of our knowledge. By using saturable absorbers with different initial transmission, the maximum pulse energy reached 4.22 mJ with peak power of 162.3 kW for a pulse duration of 26 ns. The maximum output average power amounted to 2.2 W. These results constitute significant improvement from the highest average power, pulse energy and peak power results for the PQS Tm:YLF laser to date.

Carbonyl oxides, or Criegee intermediates, are formed from the gas phase ozonolysis of alkenes and play a pivotal role in night-time and urban area atmospheric chemistry. Significant discrepancies exist among measurements of the strong (B) over tilde (1)A’-(X) over tilde (1)A’ electronic transition of the simplest Criegee intermediate, CH2OO in the visible/near-UV. We report room temperature spectra of the (B) over tilde (1)A’-(X) over tilde (1)A’ electronic absorption band of CH2OO acquired at higher resolution using both single-pass broadband absorption and cavity ring-down spectroscopy. The new absorption spectra confirm the vibrational structure on the red edge of the band that is absent from ionization depletion measurements. The absolute absorption cross sections over the 362-470 nm range are in good agreement with those reported by Ting et al. Broad-band absorption spectra recorded over the temperature range of 276-357 K were identical within their mutual uncertainties, confirming that the vibrational structure is not due to hot bands.

We present a possible molecular basis for the opposite activity of two homologues proteins that bind similar ligands and show that this is achieved by fine-tuning of the interaction interface. The highly homologous ASPP proteins have opposite roles in regulating apoptosis: ASPP2 induces apoptosis while iASPP inhibits it. The ASPP proteins are regulated by an autoinhibitory interaction between their Ank-SH3 and Pro domains. We performed a detailed biophysical and molecular study of the Pro – Ank-SH3 interaction in iASPP and compared it to the interaction in ASPP2. We found that iASPP Pro is disordered and that the interaction sites are entirely different: iASPP Ank-SH3 binds iASPP Pro via its fourth Ank repeat and RT loop while ASPP2 Ank-SH3 binds ASPP2 Pro via its first Ank repeat and the n-src loop. It is possible that by using different moieties in the same interface, the proteins can have distinct and specific interactions resulting in differential regulation and ultimately different biological activities.

An electrochemical biosensor has been developed for ultrasensitive, label‐free determination of protein kinase activity. The sensor is composed of a unique peptide monolayer on a gold electrode. It identifies the order change in the monolayer upon phosphorylation, via square wave voltametry (SWV) measurements. Disorder caused by the introduction of the phosphate groups onto the middle of the peptide sequence results in pinhole formation and therefore an increase in the electrochemical signal. The measured sensitivity was 100 nM of kinase and the dynamic range was 100 nM up to 11 μM. Sensitivity was an order of magnitude higher, and the dynamic range wider by two orders of magnitude, as compared to our previously reported impedimetric method, in which the sensitivity was 1 μM, and the dynamic range was 1–20 μM.