Coherent π0 photoproduction on the deuteron up to 4 GeV

The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions

Measurements of Deuteron Photodisintegration up to 4.0 GeV

The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.U.S. Department of Energy, National Science Foundatio

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Relative susceptibility of stored pearl millet products and fonio to insect infestation

As ready-to-use cereal products become increasingly available in Sahelian countries, higher losses to stored products insects may be expected. The susceptibility of threshed fonio (#Digitaria exilis) and of four food products derived from pearl millet (#Pennisetum glaucum) to four major pests of millet was compared to that of whole millet kernels. #Tribolium castaneum, #T. confusum, #Corcyra cephalonica and #Ephestia cautella developed on all media, but striking differences in susceptibility to attack were observed. Successive processings of millet resulted in increased susceptibility, and millet flour and semolina (sankhal) were the most susceptible to all insects. Arraw, which is obtained from millet flour, was comparatively resistant to both #Lepidoptera, but suffered heavy damage from both #Tribolium species. Of all tested products, threshed fonio was the most resistant to #C. cephalonica, but was heavily attacked by #T. confusum and #E. cautella$. (Résumé d'auteur

Antioxidant activity and acetylcholinesterase inhibition of field and in vitro grown Musa L. species

Published online: 12 October 2016Bananas and plantains (Musa L. species) have medicinal applications against diseases such as hypoglycemia, hypertension, and neurological disorders, especially Alzheimer’s disease. The demand for these plants is growing very fast, resulting in a relatively heavy load on Musaceae genetic resources. The study evaluated and compared the acetylcholinesterase (AChE) inhibition and antioxidant activity of field and in vitro plant materials of nine accessions of Musa spp. consisting of Tropical Musa banana (TMb: TMb 106, TMb 145, TMb 8, TMb 82, TMb 55) and Tropical Musa plantain (TMp: TMp 116, TMp 24, TMp 36) from the International Institute of Tropical Agriculture and Musa sapientum (MS) from the University of Ibadan Botanical garden, Nigeria. Musa accessions were estimated onto Murashige and Skoog (MS) medium supplemented with 0.18 mg/L indole acetic acid (IAA) and 4.5 mg/L benzyl amino purine (BAP). The in vitro grown accessions behaved differently with TMb 8 having the highest average shoot length of 5.03 ± 0.66 cm, and average number of leaves of 5.65 ± 0.38 cm at the end of 6 weeks. Leaf extracts provide more quantity of phenolics, flavonoids and higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity than the fruit extracts. The AChEI activity of the field plants ranged from 60.54 ± 0.54 to 98.46 ± 0.09 % and in vitro plants from 61.88 ± 0.11 to 76.60 ± 0.34 % at 200 µg/mL. Crude methanol extract (CME) of the in vitro plants showed higher DPPH antioxidant activity than the field plants with IC50 (extract concentration providing 50 % inhibition) values ranging from 9.57 ± 0.24 to 48.37 ± 0.62 µg/mL compared with CME of the field samples, which had IC50 ranging from 75.86 ± 1.76 to 162.20 ± 3.77 µg/mL. Plant tissue culture can be a reliable alternative cultivation method for mass propagation and conservation of Musa species for the production of antioxidant and acetylcholinesterase metabolites

Leaves metabolomic profiling of Musa acuminata accessions using UPLC–QTOF–MS/MS and their antioxidant activity

Musa acuminata (Musaceae) is a wild species native to South East Asia. In addition to its potential as a food crop, different non-food morphological parts of the plant have been investigated for various pharmacological activities, including anticholinesterase and antioxidant activity. This study aimed to characterize Musa leaf extracts based on their phenolic composition and their agro-morphological traits. A metabolomic approach was applied to discover biomarkers that can be used to separate eight accessions of the species originating from five different countries. Statistical analysis was employed for data analysis. The antioxidant activity and total phenolic content was measured by Ferric Reducing Antioxidant Power (FRAP) assay and Folin–Ciocalteu colorimetric method, respectively. Over 500 metabolites were observed. Thirty-one of them were important for defining variations among the accessions. The identities of some of these markers were confirmed based on their MS2 fragmentation. These include Quercetin O-rhamnoside-O hexoside (m/z 609), Kaempferol-3-O-rutinoside (m/z 593), Quercetin O hexoside (m/z 463), Hexadecanoic acid (m/z 255), Rhamnoside-O-rutinoside (m/z 623). Country of origin and methods of extraction did not play any significant role in the separation, although extraction of accessions by Soxhlet gave better yield (20.0–60.0%) than by sonication (18.4–23.0%). Accession TMp 24 from Nigeria gave the highest yield in both methods of extraction. The sonicated accession TMb 8 exhibited highest antioxidant activity having FRAP values of 49.14 mg GAE/g and 125.10 mg TROLOX/g. The next accession in FRAP activity was the sonicated leaf extract of TMb 116 with 31.69 mg GAE/g and 121.57 mg TROLOX/g. The PCA analysis allowed the separation of the accessions into two groups. The metabolomics approach was found to be informative as a screening tool of the Musa accessions. The extracts showed good antioxidant activity and can be a potential source of bioactive metabolites for industrial use

Genome-wide genotyping elucidates the geographical diversification and dispersal of the polyploid and clonally propagated yam (Dioscorea alata L.)

Open Access Article; Published online: 27 Jun 2020Background and Aims Inferring the diffusion history of many human-dispersed species is still not straightforward due to unresolved past human migrations. The centre of diversification and routes of migration of the autopolyploid and clonally propagated greater yam, Dioscorea alata, one of the oldest edible tubers, remain unclear. Here, we address yam demographic and dispersal history using a worldwide sample. Methods We characterized genome-wide patterns of genetic variation using genotyping by sequencing 643 greater yam accessions spanning four continents. First, we disentangled the polyploid and clonal components of yam diversity using allele frequency distribution and identity by descent approaches. We then addressed yam geographical origin and diffusion history with a model-based coalescent inferential approach. Key Results Diploid genotypes were more frequent than triploids and tetraploids worldwide. Genetic diversity was generally low and clonality appeared to be a main factor of diversification. The most likely evolutionary scenario supported an early divergence of mainland Southeast Asian and Pacific gene pools with continuous migration between them. The genetic make-up of triploids and tetraploids suggests that they have originated from these two regions before westward yam migration. The Indian Peninsula gene pool gave origin to the African gene pool, which was later introduced to the Caribbean region. Conclusions Our results are congruent with the hypothesis of independent domestication origins of the two main Asian and Pacific gene pools. The low genetic diversity and high clonality observed suggest a strong domestication bottleneck followed by thousands of years of widespread vegetative propagation and polyploidization. Both processes reduced the extent of diversity available for breeding, and this is likely to threaten future adaptation