Desktop classification of inland wetlands for systematic conservation planning in data‐scarce countries: mapping wetland ecosystem types,disturbance indices and threatened species associations at country‐wide scale

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Australopithecus sediba hand demonstrates mosaic evolution of locomotor and manipulative abilities

Hand bones from a single individual with a clear taxonomic affiliation are scarce in the hominin fossil record, which has hampered understanding the evolution of manipulative abilities in hominins. Here we describe and analyze a nearly complete wrist and hand of an adult female [Malapa Hominin 2 (MH2)] Australopithecus sediba from Malapa, South Africa (1.977 million years ago). The hand presents a suite of Australopithecus-like features, such as a strong flexor apparatus associated with arboreal locomotion, and Homo-like features, such as a long thumb and short fingers associated with precision gripping and possibly stone tool production. Comparisons to other fossil hominins suggest that there were at least two distinct hand morphotypes around the Plio-Pleistocene transition. The MH2 fossils suggest that Au. sediba may represent a basal condition associated with early stone tool use and production.     

Gene regulation in the third dimension

Analysis of the spatial organization of chromosomes reveals complex three-dimensional networks of chromosomal interactions. These interactions affect gene expression at multiple levels, including long-range control by distant enhancers and repressors, coordinated expression of genes, and modification of epigenetic states. Major challenges now include deciphering the mechanisms by which loci come together and understanding the functional consequences of these often transient associations.     

Yield improvement in maize for tolerance to low soil nitrogen

Low soil nitrogen limits maize (Zea mays L.) production in the West and Central African subregion. Levels of residual genetic variability were determined in two low‐N populations using selfed progeny evaluations, and results obtained indicate large genotypic and phenotypic variances for grain yield under both low‐ and high‐N environments for effective selection, while heritability estimates were generally low. Ear aspect and stay green were the most important traits contributing to grain yield for both populations. Selection reduced days to flowering, ASI and ear aspect, but increased plant height and yield. Yield gains of more than 25% occurred for the two populations under both low and high N with the most significant change of 42% occurring in one population under high N.     

Three-dimensional modelling of wood fracture in mode I, perpendicular to the grain direction at fibre level

A coupled experimental and numerical modelling approach was used to investigate the mechanism of softwood fracture at the fibre level. First, a three-dimensional mixed lattice-continuum fracture model was developed to investigate the mechanism of wood fracture, taking into account the porosity of its structure and its heterogeneities at the fibre level. The critical volumes in the specimen where crack propagation was more probable were modelled by a lattice that could show the alternation of earlywood and latewood fibres, and the other regions were considered as the continuum medium. The proposed model was used to investigate the mode I fracture of a small softwood sample in RL orientation. Secondly, a method was developed for microscopic observation of the crack trajectory and investigating the mechanism of initiation and propagation of cracks. This approach was used for microscopic investigation of the fracture behaviour of spruce specimens in mode I and RL orientation. The results of the numerical study were compared with the experimental results. The prepeak and postpeak behaviour of the obtained stress-displacement curve and also the crack opening trajectory in cross-section and longitudinal section in the model and experiments were in good agreement. Both the model and the microscopic observation showed that in mode I fracture and RL orientation, the main trajectory of the crack propagates in the earlywood ring.     

Assessment of heterotic patterns of tropical low-nitrogen–tolerant maize (Zea mays L.) inbred lines using testcross performance,morphological traits and SNP markers

Breeding efforts in West and Central Africa (WCA) have focused on the development of Low-N-tolerant (LNT) maize inbreds and their classification into heterotic groups. This study was conducted to classify LNT maize lines into heterotic groups using testcross performance, morphological and SNP markers and to compare the consistency of groupings by the three methods. Thirty-six LNT inbreds were crossed to two contrasting inbred testers to generate 72 testcrosses that were evaluated under low-N conditions in Nigeria in 2014. Also, the 36 inbreds and the two testers were evaluated for per se performance under similar conditions as the testcrosses in 2014 and genotyped in 2015 using 1,123,196 SNP markers. Based on testcross performance, 33 of the 36 LNT inbreds were grouped by the two testers. Morphological characterization from per se performance and genetic relationship by SNP markers classified the inbreds into four groups that were inconsistent with their pedigree. Correlation analysis showed non-concurrence of the three grouping methods. However, information from these groupings would assist in reducing the number of crosses to be made and evaluated.     

Mitigating N2O and NO Emissions from Direct-Seeded Rice with Nitrification Inhibitor and Urea Deep Placement

Soil-emitted nitrous oxide (N₂O) and nitric oxide (NO) in crop production are harmful nitrogen (N) emissions that may contribute both directly and indirectly to global warming. Application of nitrification inhibitors, such as dicyandiamide (DCD), and urea deep placement (UDP), are considered effective approaches to reduce these emissions. This study investigated the effects of DCD and UDP, compared to urea and potassium nitrate, on emissions, nitrogen use efficiency and grain yields under direct-seeded rice. High-frequency measurements of N₂O and NO emissions were conducted using the automated closed chamber method throughout the crop-growing season and during the ratoon crop. Both UDP and DCD were effective in reducing N₂O emissions by 95% and 73%, respectively. The highest emission factor (1.53% of applied N) was observed in urea, while the lowest was in UDP (0.08%). Emission peaks were mainly associated with fertilization events and appeared within one to two weeks of fertilization. Those emission peaks contributed to 65%–98% of the total seasonal emissions. Residual effects of fertilizer treatments on the N₂O emissions from the ratoon crop were not significant; however, the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions. On the other hand, cumulative NO emissions were not significant in either the rice or ratoon crops. UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea. The results suggested that the use of DCD and UDP could mitigate N₂O emissions and increase grain yields and nitrogen use efficiency under direct-seeded rice condition.     

A bacterial protein targets the BAHD1 chromatin complex to stimulate type III interferon response

Intracellular pathogens such as Listeria monocytogenes subvert cellular functions through the interaction of bacterial effectors with host components. Here we found that a secreted listerial virulence factor, LntA, could target the chromatin repressor BAHD1 in the host cell nucleus to activate interferon (IFN)-stimulated genes (ISGs). IFN-λ expression was induced in response to infection of epithelial cells with bacteria lacking LntA; however, the BAHD1-chromatin associated complex repressed downstream ISGs. In contrast, in cells infected with lntA-expressing bacteria, LntA prevented BAHD1 recruitment to ISGs and stimulated their expression. Murine listeriosis decreased in BAHD1(+/-) mice or when lntA was constitutively expressed. Thus, the LntA-BAHD1 interplay may modulate IFN-λ-mediated immune response to control bacterial colonization of the host.