Downdip development of the Ni‐Cu‐PGE‐bearing mafic to ultramafic uitkomst complex, Mpumalanga province, South Africa

The about 2055-Ma-old mafic to ultramafic Uitkomst Complex in the Mpumalanga Province of South Africa hosts the low-grade-large-tonnage Ni-Cu-PGE deposit, Nkomati. The complex is regarded to represent a satellite to the Bushveld Complex and a feeder to an eroded magmatic reservoir in the southeast. Aeromagnetic surveys and previous drilling indicated an overall northwestern-downdip extension of the complex, but the question is to what extent and in which expression can the complete intrusion be found under cover in the northwest? Answering this, a mineralogical, geochemical and geochronological investigation of a borehole intersection of the whole complex at Little Mamre was carried out, using petrography, XRF, EPMA and LA-ICP-MS U–Pb analyses of zircons for age determination. Although the total thickness of the rock units is larger than to the southeast, emplacement, litho- and mineral chemistry trends, expression of alteration mineralogy and style of sulphide mineralisation are similar. The amount of sulphide mineralisation is on average less than in the southeast. The upper ultramafic unit contains, more frequently, pegmatoidal sections, and the Chromitiferous Harzburgite unit has less massive chromitite layers than the southeastern parts of the complex, whereas the gabbro(-norite) units contain more interstitial liquid with late-stage minerals. The findings confirm that the anvil-shaped intrusion in cross section continues with increased thickness towards northwest at a shallow dip; although approaching the deeper part of the igneous reservoir, mineral compositions are partially more evolved. The overall mineralogical consistency downdip supports a situation of multiple magma replenishment along a flat-lying, northwest–southeast trending conduit, resulting in an evolved cumulus mineral assemblage in the upper part

A CRR2-Dependent sRNA Sequence Supports Papillomavirus Vaccine Expression in Tobacco Chloroplasts

Introduction: Human papillomavirus (HPV) infection is the leading cause of cervical cancer, and vaccination with HPV L1 capsid proteins has been successful in controlling it. However, vaccination coverage is not universal, particularly in developing countries, where 80% of all cervical cancer cases occur. Cost-effective vaccination could be achieved by expressing the L1 protein in plants. Various efforts have been made to produce the L1 protein in plants, including attempts to express it in chloroplasts for high-yield performance. However, manipulating chloroplast gene expression requires complex and difficult-to-control expression elements. In recent years, a family of nuclear-encoded, chloroplast-targeted RNA-binding proteins, the pentatricopeptide repeat (PPR) proteins, were described as key regulators of chloroplast gene expression. For example, PPR proteins are used by plants to stabilize and translate chloroplast mRNAs. Objectives: To demonstrate that a PPR target site can be used to drive HPV L1 expression in chloroplasts. Methods: To test our hypothesis, we used biolistic chloroplast transformation to establish tobacco lines that express two variants of the HPV L1 protein under the control of the target site of the PPR protein CHLORORESPIRATORY REDUCTION2 (CRR2). The transgenes were inserted into a dicistronic operon driven by the plastid rRNA promoter. To determine the effectiveness of the PPR target site for the expression of the HPV L1 protein in the chloroplasts, we analyzed the accumulation of the transgenic mRNA and its processing, as well as the accumulation of the L1 protein in the transgenic lines. Results: We established homoplastomic lines carrying either the HPV18 L1 protein or an HPV16B Enterotoxin::L1 fusion protein. The latter line showed severe growth retardation and pigment loss, suggesting that the fusion protein is toxic to the chloroplasts. Despite the presence of dicistronic mRNAs, we observed very little accumulation of monocistronic transgenic mRNA and no significant increase in CRR2-associated small RNAs. Although both lines expressed the L1 protein, quantification using an external standard suggested that the amounts were low. Conclusions: Our results suggest that PPR binding sites can be used to drive vaccine expression in plant chloroplasts; however, the factors that modulate the effectiveness of target gene expression remain unclear. The identification of dozens of PPR binding sites through small RNA sequencing expands the set of expression elements available for high-value protein production in chloroplasts.German Research Foundation, DFGPeer Reviewe

Leader Cells Define Directionality of Trunk, but Not Cranial, Neural Crest Cell Migration.

Collective cell migration is fundamental for life and a hallmark of cancer. Neural crest (NC) cells migrate collectively, but the mechanisms governing this process remain controversial. Previous analyses in Xenopus indicate that cranial NC (CNC) cells are a homogeneous population relying on cell-cell interactions for directional migration, while chick embryo analyses suggest a heterogeneous population with leader cells instructing directionality. Our data in chick and zebrafish embryos show that CNC cells do not require leader cells for migration and all cells present similar migratory capacities. In contrast, laser ablation of trunk NC (TNC) cells shows that leader cells direct movement and cell-cell contacts are required for migration. Moreover, leader and follower identities are acquired before the initiation of migration and remain fixed thereafter. Thus, two distinct mechanisms establish the directionality of CNC cells and TNC cells. This implies the existence of multiple molecular mechanisms for collective cell migration.D11I1096 Fondo de Fomento al Desarrollo Científico y TecnológicoThis is the final version of the article. It first appeared from Cell Press via httsp://doi.org/10.1016/j.celrep.2016.04.06

Microscopic multifrequency MR elastography for mapping viscoelasticity in zebrafish

Purpose: The zebrafish (Danio rerio) has become an important animal model in a wide range of biomedical research disciplines. Growing awareness of the role of biomechanical properties in tumor progression and neuronal development has led to an increasing interest in the noninvasive mapping of the viscoelastic properties of zebrafish by elastography methods applicable to bulky and nontranslucent tissues. Methods: Microscopic multifrequency MR elastography is introduced for mapping shear wave speed (SWS) and loss angle (φ) as markers of stiffness and viscosity of muscle, brain, and neuroblastoma tumors in postmortem zebrafish with 60 µm in-plane resolution. Experiments were performed in a 7 Tesla MR scanner at 1, 1.2, and 1.4 kHz driving frequencies. Results: Detailed zebrafish viscoelasticity maps revealed that the midbrain region (SWS = 3.1 ± 0.7 m/s, φ = 1.2 ± 0.3 radian [rad]) was stiffer and less viscous than telencephalon (SWS = 2.6 ± 0. 5 m/s, φ = 1.4 ± 0.2 rad) and optic tectum (SWS = 2.6 ± 0.5 m/s, φ = 1.3 ± 0.4 rad), whereas the cerebellum (SWS = 2.9 ± 0.6 m/s, φ = 0.9 ± 0.4 rad) was stiffer but less viscous than both (all p < .05). Overall, brain tissue (SWS = 2.9 ± 0.4 m/s, φ = 1.2 ± 0.2 rad) had similar stiffness but lower viscosity values than muscle tissue (SWS = 2.9 ± 0.5 m/s, φ = 1.4 ± 0.2 rad), whereas neuroblastoma (SWS = 2.4 ± 0.3 m/s, φ = 0.7 ± 0.1 rad, all p < .05) was the softest and least viscous tissue. Conclusion: Microscopic multifrequency MR elastography-generated maps of zebrafish show many details of viscoelasticity and resolve tissue regions, of great interest in neuromechanical and oncological research and for which our study provides first reference values

Integration of landslide hazard into urban planning across Europe

[EN] An enquiry-based and participatory analysis approach is carried out to identify the strengths and weaknesses in the heterogeneous legislations across Europe that regulate the integration of landslide hazard into urban planning. Twenty one national and eight regional Geological Surveys (GSs) have participated in the analysis. The GSs report almost 4000 recent (2015–2017) damaging landslides events resulting in 39 fatalities and 155 injuries, destruction to housing, infrastructure and properties. In addition, 11 countries report 18 MORLE events over the past 10 years responsible for 150 fatalities and severe economic impacts. Results also reveal almost 48 million people living in areas with high and very high degrees of landslide-susceptibility (around 1 million km2 according to ELSUS v2). This work shows that almost half the participating countries (10 countries) have no legal guidance in the National Land Bill to stipulate consideration of landslides in urban planning practices, and mapping tools are often not adapted to a standard required to inform sustainable development. Furthermore, there is a wide range of laws and a large heterogeneity of mapping methods, scales and procedures. A relevant deficiency detected in many countries is the lack of landslide maps at a detailed resolution for urban planning. Additionally, some case studies of suboptimal urban development practices in areas of known instability have been discussed; they are found to be related to weak rule of law and/or absence of good governance. This paper shows inconsistencies across Europe in the handling of landslides and proposes a series of key actions to improve this situation, highlighting the need for a common regulatory framework to deal with this geohazard appropriately.This survey has been developed within the framework of the Earth Observation and Geohazard Expert Group (EOEG) from EuroGeoSurveys and was funded by the European Commission, Directorate-General Humanitarian Aid and Civil Protection (ECHO), through the project U-Geohaz: Geohazard Impact Assessment for Urban Areas. Grant Agreement No. 783169. This work has been partly funded by Salvador de Madariaga Mobility Program from the Spanish Ministry of Science, projects: PRX18/00020 and PRX19/00065.Peer reviewe

Downdip Development of the Ni-Cu-PGE-Bearing Mafic to Ultramafic Uitkomst Complex, Mpumalanga Province, South Africa

The about 2055-Ma-old mafic to ultramafic Uitkomst Complex in the Mpumalanga Province of South Africa hosts the low-grade-large-tonnage Ni-Cu-PGE deposit, Nkomati. The complex is regarded to represent a satellite to the Bushveld Complex and a feeder to an eroded magmatic reservoir in the southeast. Aeromagnetic surveys and previous drilling indicated an overall northwestern-downdip extension of the complex, but the question is to what extent and in which expression can the complete intrusion be found under cover in the northwest? Answering this, a mineralogical, geochemical and geochronological investigation of a borehole intersection of the whole complex at Little Mamre was carried out, using petrography, XRF, EPMA and LA-ICP-MS U&ndash;Pb analyses of zircons for age determination. Although the total thickness of the rock units is larger than to the southeast, emplacement, litho- and mineral chemistry trends, expression of alteration mineralogy and style of sulphide mineralisation are similar. The amount of sulphide mineralisation is on average less than in the southeast. The upper ultramafic unit contains, more frequently, pegmatoidal sections, and the Chromitiferous Harzburgite unit has less massive chromitite layers than the southeastern parts of the complex, whereas the gabbro(-norite) units contain more interstitial liquid with late-stage minerals. The findings confirm that the anvil-shaped intrusion in cross section continues with increased thickness towards northwest at a shallow dip; although approaching the deeper part of the igneous reservoir, mineral compositions are partially more evolved. The overall mineralogical consistency downdip supports a situation of multiple magma replenishment along a flat-lying, northwest&ndash;southeast trending conduit, resulting in an evolved cumulus mineral assemblage in the upper part