Chemical compounds that may be used as sources for dihydrogen are discussed. In particular, the use of ammonia-borane and related compounds as hydrogen donors are examined.
The Role of Cholesterol in Cancer Kuzu, Omer F; Noory, Mohammad A; Robertson, Gavin P
Cancer research,
04/2016, Letnik:
76, Številka:
8
Journal Article
Row-crop agriculture is a major source of nitrous oxide (N₂O) globally, and results from recent field experiments suggest that significant decreases in N₂O emissions may be possible by decreasing ...nitrogen (N) fertilizer inputs without affecting economic return from grain yield. We tested this hypothesis on five commercially farmed fields in Michigan, USA planted with corn in 2007 and 2008. Six rates of N fertilizer (0-225 kg N ha⁻¹) were broadcast and incorporated before planting, as per local practice. Across all sites and years, increases in N₂O flux were best described by a nonlinear, exponentially increasing response to increasing N rate. N₂O emission factors per unit of N applied ranged from 0.6% to 1.5% and increased with increasing N application across all sites and years, especially at N rates above those required for maximum crop yield. At the two N fertilizer rates above those recommended for maximum economic return (135 kg N ha⁻¹), average N₂O fluxes were 43% (18 g N₂O-N ha⁻¹ day⁻¹) and 115% (26 g N₂O-N ha⁻¹ day⁻¹) higher than were fluxes at the recommended rate, respectively. The maximum return to nitrogen rate of 154 kg N ha⁻¹ yielded an average 8.3 Mg grain ha⁻¹. Our study shows the potential to lower agricultural N₂O fluxes within a range of N fertilization that does not affect economic return from grain yield.
Amine and phosphine adducts are classic examples of compounds synthesized by Lewis acid-Lewis base reactions. An examination of research into new applications for these old compounds is presented.
Despite the widespread interest in direct neuronal reprogramming, the mechanisms underpinning fate conversion remain largely unknown. Our study revealed a critical time point after which cells either ...successfully convert into neurons or succumb to cell death. Co-transduction with Bcl-2 greatly improved negotiation of this critical point by faster neuronal differentiation. Surprisingly, mutants with reduced or no affinity for Bax demonstrated that Bcl-2 exerts this effect by an apoptosis-independent mechanism. Consistent with a caspase-independent role, ferroptosis inhibitors potently increased neuronal reprogramming by inhibiting lipid peroxidation occurring during fate conversion. Genome-wide expression analysis confirmed that treatments promoting neuronal reprogramming elicit an anti-oxidative stress response. Importantly, co-expression of Bcl-2 and anti-oxidative treatments leads to an unprecedented improvement in glial-to-neuron conversion after traumatic brain injury in vivo, underscoring the relevance of these pathways in cellular reprograming irrespective of cell type in vitro and in vivo.
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•Oxidative stress is a major hurdle in converting different cell types into neurons•Ferroptosis inhibitors and antioxidants improve direct neuronal reprogramming•Bcl-2 reduces ROS and promotes direct neuronal reprogramming also in vivo•Antioxidants potently improve maturation of induced neurons in vitro and in vivo
By imaging cell fate conversion over time, Gascón, Murenu, and colleagues find that high levels of oxidative stress prevent successful direct neuronal reprogramming, instead causing extensive cell death. They identify inhibitors of ferroptosis, antioxidants, and Bcl-2 as key metabolic agents in improving generation of iNs from a range of somatic cells and in vivo after brain injury.
The origins of the RNA world Robertson, Michael P; Joyce, Gerald F
Cold Spring Harbor perspectives in biology,
05/2012, Letnik:
4, Številka:
5
Journal Article
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The general notion of an "RNA World" is that, in the early development of life on the Earth, genetic continuity was assured by the replication of RNA and genetically encoded proteins were not ...involved as catalysts. There is now strong evidence indicating that an RNA World did indeed exist before DNA- and protein-based life. However, arguments regarding whether life on Earth began with RNA are more tenuous. It might be imagined that all of the components of RNA were available in some prebiotic pool, and that these components assembled into replicating, evolving polynucleotides without the prior existence of any evolved macromolecules. A thorough consideration of this "RNA-first" view of the origin of life must reconcile concerns regarding the intractable mixtures that are obtained in experiments designed to simulate the chemistry of the primitive Earth. Perhaps these concerns will eventually be resolved, and recent experimental findings provide some reason for optimism. However, the problem of the origin of the RNA World is far from being solved, and it is fruitful to consider the alternative possibility that RNA was preceded by some other replicating, evolving molecule, just as DNA and proteins were preceded by RNA.
Whole soil profile assessments of soil C stocks are enormously important for evaluating a soil's potential for sequestering C. Carbon stock measurements are often highly variable, which makes the ...detection of statistically significant differences among different land uses and management systems difficult. A common mistake is to interpret a lack of statistical significance as evidence for the absence of differences. This mistake is costly: failure to identify practices and habitats that accumulate C can affect our understanding of soil C cycling and hide possible sequestration potentials. In this study, we investigated inadequate replication as a major cause of a lack of statistical significance. Power analysis is a well-established statistical tool that allows researchers to infer whether the lack of statistical significance is due to the absence of meaningful differences or due to insufficient replication. We used data from two published studies to illustrate the value of power analysis. In particular, we showed that in these studies the chances of detecting even substantial (e.g., 50%) differences among experimental treatments can be as low as 20 to 60% due to the natural variability in soil C concentrations and stocks. Carbon variability in different soil horizons suggests that statistical analyses of soil C stocks should be conducted separately for each sampled horizon and that conclusions about the profile as a whole should be made based on the individual horizon results. Devising an optimal sampling strategy that identifies the appropriate number of replicates needed to detect significant C change by horizon is essential.
Increasing the potential of soil to store carbon (C) is an acknowledged and emphasized strategy for capturing atmospheric CO
. Well-recognized approaches for soil C accretion include reducing soil ...disturbance, increasing plant biomass inputs, and enhancing plant diversity. Yet experimental evidence often fails to support anticipated C gains, suggesting that our integrated understanding of soil C accretion remains insufficient. Here we use a unique combination of X-ray micro-tomography and micro-scale enzyme mapping to demonstrate for the first time that plant-stimulated soil pore formation appears to be a major, hitherto unrecognized, determinant of whether new C inputs are stored or lost to the atmosphere. Unlike monocultures, diverse plant communities favor the development of 30-150 µm pores. Such pores are the micro-environments associated with higher enzyme activities, and greater abundance of such pores translates into a greater spatial footprint that microorganisms make on the soil and consequently soil C storage capacity.
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