Paleomagnetic dating of the Enticho sandstone at negash locality (Tigrai Region, northern Ethiopia): implication for quaternary remagnetization

New paleomagnetic result is reported from the Enticho Sandstone (Late Paleozoic age) at Negash locality in Northern Ethiopia. Twenty-three paleomagnetic core samples were collected from three sites for paleomagnetic investigations. Specimens were subjected either to progressive alternating field (af) or thermal (th) demagnetization techniques. Rock magnetic experiments revealed major magnetization carriers to be titano-magnetite and titano-hematite. Well-defined viscous remanent magnetizations (vrm) components are removed by intermediate af fields of between 20–30 mT and heating above 600ºC. These magnetizations defining straight-line segments are directed towards the origin and interpreted as the Characteristic Remanent Magnetization (ChRM). Directions of magnetizations and site-mean directions in the in-situ coordinate results in Dec = 356.7°, Inc = 24.9º (N=23, K = 43, a95 = 4.7°). Paleomagnetic stability tests confirmed that the ChRMs identified are secondary and postdate age of deposition and tectonic tilting. The paleomagnetic pole position Long = 296.6ºE, Lat = 86.7ºN (A95 = 5.0º, N = 23) obtained from these data when plotted with the Apparent Polar Wander Path (apwp) of Africa (Besse and Courtillot, 1991, 2003; Cogné, 2003) gives a Quaternary age for the magnetization of Enticho Sandstone at Negash locality. Comparison of this result with that of Enticho Sandstone at Enticho locality, which had primary magnetization fingerprints (Tesfaye Kidane et al., 2013) with ages of between 260 Ma and 270 Ma (Late Carboniferous – Early Permian) implies that the Quaternary age for the Enticho Sandstone at Negash is a recent remagnetization

Pleistocene aragonite crust diagenesis mimics microbialite fabrics (Danakil Depression, Ethiopia)

Fibrous aragonite crusts occur in two consecutive Pleistocene successions in the Danakil Depression (Afar, Ethiopia). Lateral transitions between pristine and altered fibrous aragonite crusts document changes in texture associated with diagenesis. Crusts formed as essentially abiotic seafloor precipitates at the transition from marine to evaporitic conditions. Diagenesis started with the dissolution of aragonite fans at the interface between single fans in non-laminated crusts and along lamination planes in isopachous, irregular, or crudely laminated crusts. Incomplete dissolution resulted in the development of secondary porosity within a matrix of undissolved aragonite fibers. Subsequently, the porosity was filled with calcite that systematically encased remaining aragonite crystals. This was followed by the dissolution of remnant aragonite fibers, producing a network of elongated inter- and intracrystalline pores that were eventually filled with low-Mg calcite. The stepwise substitution of fibrous aragonite by low-Mg calcite resulted in sparry, sparry-cloudy, sparry-micritic (including clotted micrite), and peloidal textures, which obscure the fibrous nature of the original deposits. Stable C- and O-isotope compositions suggest that early diagenesis was driven by meteoric and evaporative fluids. These observations unequivocally demonstrate destructive diagenesis, resulting in secondary textures, which mimic micritic and grumous (peloidal and clotted) textures associated with sparry microfabrics. This suggests that these textures, classically interpreted as primary microbial precipitates and used as evidence of biogenicity in ancient microbialites, might be diagenetic products in some cases, even though at some stage, microbial processes and/or degradation of organic matter could have been involved in the diagenetic process

Pleistocene sea-floor fibrous crusts and spherulites in the Danakil Depression (Afar, Ethiopia)

Pleistocene fibrous aragonite fabrics, including crusts and spherules, occur in the Danakil Depression (Afar, Ethiopia) following the deposition of two distinctive Middle and Late Pleistocene coralgal reef units and pre‐dating the precipitation of evaporites. Crusts on top of the oldest reef unit (Marine Isotope Stage 7) cover and fill cavities within a red algal framework. The younger aragonite crusts directly cover coralgal bioherms (Marine Isotope Stage 5) and associated deposits. Their stratigraphic position between marine and evaporitic deposits, and their association to euryhaline molluscs, suggest that the crusts and spherules formed in restricted semi‐enclosed conditions. The availability of hard substrate controls crust formation with crusts more often found on steep palaeo‐slopes, from sea level up to at least 80 m depth, while spherules mainly occur associated with mobile substrate. Crusts reach up to 30 cm in thickness and can be microdigitate, columnar (branching and non‐branching) or non‐ columnar, with laminated and non‐laminated fabrics. Two different lamination types are found within the crystalline fabrics: (i) isopachous lamination; and (ii) irregular lamination. These two types of lamination can be distinguished by the organization of the aragonite fibres, as well as the lateral continuity of the laminae. Scanning electron microscopy with energy dispersive X‐ray spectroscopy analyses on well‐preserved samples revealed the presence of Mg‐silicate laminae intercalated with fibrous aragonite, as well as Mg‐silicate aggregates closely associated with the fibrous aragonite crusts and spherules. The variety of observed fabrics results from a continuum of abiotic and microbial processes and, thus, reflects the tight interaction between microbially mediated and abiotic mineralization mechanisms. These are the youngest known isopachously laminated, digitate and columnar branching fibrous crusts associated with a transition from marine to evaporitic conditions. Understanding the context of formation of these deposits in Afar can help to better interpret the depositional environment of the widespread Precambrian sea‐floor precipitates

Wheat varietal diversification increases Ethiopian smallholders’ food security: Evidence from a participatory development initiative

This study assesses the impact of a participatory development program called Seeds For Needs, carried out in Ethiopia to support smallholders in addressing climate change and its consequences through the introduction, selection, use, and management of suitable crop varieties. A doubly robust estimator was employed to properly estimate the impact of Seeds For Needs interventions. The results show that program activities have significantly enhanced wheat crop productivity and smallholders’ food security by increasing wheat varietal diversification. This paper provides further empirical evidence for the effective role that varietal diversity can play in improving food security in marginal environments, and also provides clear indications for development agencies regarding the importance of improving smallholders’ access to crop genetic resources

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic

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

Identification of Stripe Rust Resistance in Ethiopian Durum Wheat by Phenotypic Screening and Kompetitive Allele Specific PCR (KASP) SNP Markers

Stripe (Yellow) rust caused by Puccinia striiformis f.sp. tritici (Pst) is one of the most devastating diseases of wheat in the highlands of Ethiopia. Improved cultivars often lose their resistance due to occurrence of new virulent races which overcome the genes and make the cultivars out of production. Therefore, identification of new sources of resistance genes helps in battling yellow rust and maximizes wheat production in Ethiopia. In this study, 300 durum wheat lines (landraces & cultivars) were screened with three virulent isolates (Pst_Is1, Pst_Is4 and Pst_Is8) for seedling resistance using Infection Type (IT) scoring method. The lines were also screened with 16 KASP-based SNP markers linked to 7 Yr genes already identified in various studies. Highly resistant infection type (IT: 0 -3) to Pst_Is1, Pst_Is4, and Pst_Is8 was exhibited by 59.3%; 67.3%; and 46.3% of the lines, respectively. 124 lines constantly exhibited high level of resistance to all three isolates. The majority (96.8%) of the resistant lines are landraces while four (3.2%) are commercial cultivars (Cocorit/71, Yerer, Obsa and Dire). In the molecular screening 12 of the markers gave clear amplifications in the controls and the tested lines. Yr7, Yr15 and YrSp were detected in 81.7%, 88.3% and 0.7% of the lines respectively while Yr1, Yr17 and Yr36 were not detected. Detection frequency was higher in landraces (58.7%) than in cultivars (32.8%). Gene combinations frequency was the highest (72.7%) for Yr7+Yr15 followed by Yr15+YrSp (0.3%). Overall, this study has resulted in detection of genes Yr15 and YrSp, which are potential candidates for marker assisted breeding for Pst resistance in wheat. Besides, it has shown that resistant source identification and detection of genes can be facilitated through combined application of phenotyping and molecular screening