An evaluation of the global potential of bioenergy production on degraded lands

In this article the global potential of energy crop production on degraded lands was estimated using detailed, spatially explicit data about the area, type and extent of degradation derived from the Global Assessment of Land Degradation Dataset, and by combining this dataset with various spatially explicit data sets. Next, an estimate was made of the possible yield of perennial energy crops on the degraded areas as a function of the type and degree of degradation. Lightly degraded areas were not included, as these areas might be suitable for conventional food production. The total global potential energy production on degraded lands was assessed to be slightly above 150 and 190 EJ yr^?1, for grassy and woody energy crops, respectively. Most of this potential, however, is on areas currently classified as forest, cropland or pastoral land, leaving a potential of around 25 and 32 EJ yr^?1 on other land cover categories. Most of the potential energy crop production on degraded land is located in developing regions. China has a total potential of 30 EJ yr^?1, of which 4 EJ yr^?1 from areas classified as other land. Also USA, Brazil, West Africa, East Africa, Russia and India have substantial potentials of 12–18 EJ yr^?1, with up to 30% of the potential from areas classified as other land.     

Tetramethylputrescine from young plants of Ruellia rosea

Tetramethylputrescine was isolated from the roots and aerial parts of Ruellia rosea. The compound was characterized by MS, ¹³C-NMR-spectroscopy and comparison with a synthetic specimen.     

Secondary structure of peptides: 8. 13C n.m.r. CP/MAS investigation of solid poly(l-leucines) and poly(d-norvalines) prepared from N-carboxyanhydrides

¹³C n.m.r. CP/MAS spectra (50.3 and 75.4 MHz) of solid poly(l-lleucines) and poly(d-norvalines) measured with suitable acquisition parameters allow quantification of the composition of the secondary structure. The optimum acquisition parameters were found by systematic variation of the contact time by means of samples containing 5?0% α-helix structure. The polypeptides were prepared by primary or tertiary amine-initiated polymerizations of the corresponding amino acid NCAs and the average degrees of polymerization ($\text{DP}$) were determined by ¹H n.m.r. endgroup analysis. The mole fraction of α-helices increases with increasing $\text{DP}$; it depends on the nature of the solvent and to a lesser degree on the polymerization temperature. When prepared under identical conditions, poly(d-norvaline) samples contain more β-sheet structure than poly(l-leucine. Reprecipitation increases the α-helix content, demonstrating that a part of the original β-sheet structure is thermodynamically unstable. The presence of oligomers of $\text{DP}$ ?10 is mainly responsible for the thermodynamically stable part of the β-sheet structure. The chain growth mechanism is discussed.     

Drainage-structuring of ancestral variation and a common functional pathway shape limited genomic convergence in natural high- and low-predation guppies

Studies of convergence in wild populations have been instrumental in understanding adaptation by providing strong evidence for natural selection. At the genetic level, we are beginning to appreciate that the re-use of the same genes in adaptation occurs through different mechanisms and can be constrained by underlying trait architectures and demographic characteristics of natural populations. Here, we explore these processes in naturally adapted high- (HP) and low-predation (LP) populations of the Trinidadian guppy, Poecilia reticulata. As a model for phenotypic change this system provided some of the earliest evidence of rapid and repeatable evolution in vertebrates; the genetic basis of which has yet to be studied at the whole-genome level. We collected whole-genome sequencing data from ten populations (176 individuals) representing five independent HP-LP river pairs across the three main drainages in Northern Trinidad. We evaluate population structure, uncovering several LP bottlenecks and variable between-river introgression that can lead to constraints on the sharing of adaptive variation between populations. Consequently, we found limited selection on common genes or loci across all drainages. Using a pathway type analysis, however, we find evidence of repeated selection on different genes involved in cadherin signaling. Finally, we found a large repeatedly selected haplotype on chromosome 20 in three rivers from the same drainage. Taken together, despite limited sharing of adaptive variation among rivers, we found evidence of convergent evolution associated with HP-LP environments in pathways across divergent drainages and at a previously unreported candidate haplotype within a drainage.     

Deep haplotype analyses of target-site resistance locus ACCase in blackgrass enabled by pool-based amplicon sequencing

Rapid adaptation of weeds to herbicide applications in agriculture through resistance development is a widespread phenomenon. In particular, the grass Alopecurus myosuroides is an extremely problematic weed in cereal crops with the potential to manifest resistance in only a few generations. Target-site resistances (TSRs), with their strong phenotypic response, play an important role in this rapid adaptive response. Recently, using PacBio's long-read amplicon sequencing technology in hundreds of individuals, we were able to decipher the genomic context in which TSR mutations occur. However, sequencing individual amplicons are costly and time-consuming, thus impractical to implement for other resistance loci or applications. Alternatively, pool-based approaches overcome these limitations and provide reliable allele frequencies, although at the expense of not preserving haplotype information. In this proof-of-concept study, we sequenced with PacBio High Fidelity (HiFi) reads long-range amplicons (13.2 kb), encompassing the entire ACCase gene in pools of over 100 individuals, and resolved them into haplotypes using the clustering algorithm PacBio amplicon analysis (pbaa), a new application for pools in plants and other organisms. From these amplicon pools, we were able to recover most haplotypes from previously sequenced individuals of the same population. In addition, we analysed new pools from a Germany-wide collection of A. myosuroides populations and found that TSR mutations originating from soft sweeps of independent origin were common. Forward-in-time simulations indicate that TSR haplotypes will persist for decades even at relatively low frequencies and without selection, highlighting the importance of accurate measurement of TSR haplotype prevalence for weed management.     

Spin Trapping of Inorganic Radicals

The use of nitrose compounds and nitrones as spin traps for the detection of short-lived inorganic radicals is discussed. To a certain degree nitrones and nitroso compounds are complementary. While nitroso compounds are superior with respect to spin trapping metal-centred radicals, nitrones form more persistent spin adducts with most small inorganic radicals.

Erroneous results may be obtained when hydrolysis and redox reactions involving the spin adducts are ignored. Spin trapping of pseudohalide radicals (·N_j· ·CN, ·SCN) are discussed in more detail.     

Considering human toxicity as an impact category in life cycle assessment

Characterization of toxic chemicals with relevance to human exposure does normally not belong to Life Cycle Assessments (LCA) and is still a topic of research. The concept of hazard potential classes proposed in this paper is primarily based on threshold limit values that are considered to be a measure of the severity of potential effects. In the absence of threshold limit values the R-phrases of the ordinance of dangerous substances are used. Substances are assigned to five hazard potential classes (A to E). Potentially dangerous chemicals are identified and substances of low toxicological relevance are excluded from further evaluation. The location where a probable exposure might occur (indoor versus outdoor) and inter-media transport of substances is considered. The product comparison is based both on the results of the proposed “semi-quantitative screening method” and on toxicological expert knowledge.