A smart telerobotic system driven by monocular vision

A robotic system that accepts autonomously generated motion and control commands is described. The system provides images from the monocular vision of a camera mounted on a robot's end effector, eliminating the need for traditional guidance targets that must be predetermined and specifically identified. The telerobotic vision system presents different views of the targeted object relative to the camera, based on a single camera image and knowledge of the target's solid geometry

Phytochrome Mediated Responses in Agrobacterium fabrum: Growth, Motility and Plant Infection

The soil bacterium and plant pathogen Agrobacterium fabrum C58 has two phytochrome photoreceptors, Agp1 and Agp2. We found that plant infection and tumor induction by A. fabrum is down-regulated by light and that phytochrome knockout mutants of A. fabrum have diminished infection rates. The regulation pattern of infection matches with that of bacterial conjugation reported earlier, suggesting similar regulatory mechanisms. In the regulation of conjugation and plant infection, phytochromes are active in darkness. This is a major difference to plant phytochromes, which are typically active after irradiation. We also found that propagation and motility were affected in agp1− and agp2− knockout mutants, although propagation was not always affected by light. The regulatory patterns can partially but not completely be explained by modulated histidine kinase activities of Agp1 and Agp2. In a mass spectrometry-based proteomic study, 24 proteins were different between light and dark grown A. fabrum, whereas 382 proteins differed between wild type and phytochrome knockout mutants, pointing again to light independent roles of Agp1 and Agp2

Key Amino Acids in the Bacterial (6-4) Photolyase PhrB from Agrobacterium fabrum

Photolyases can repair pyrimidine dimers on the DNA that are formed during UV irradiation. PhrB from Agrobacterium fabrum represents a new group of prokaryotic (6–4) photolyases which contain an iron-sulfur cluster and a DMRL chromophore. We performed site-directed mutagenesis in order to assess the role of particular amino acid residues in photorepair and photoreduction, during which the FAD chromophore converts from the oxidized to the enzymatically active, reduced form. Our study showed that Trp342 and Trp390 serve as electron transmitters. In the H366A mutant repair activity was lost, which points to a significant role of His366 in the protonation of the lesion, as discussed for the homolog in eukaryotic (6–4) photolyases. Mutants on cysteines that coordinate the Fe-S cluster of PhrB were either insoluble or not expressed. The same result was found for proteins with a truncated C-terminus, in which one of the Fe-S binding cysteines was mutated and for expression in minimal medium with limited Fe concentrations. We therefore assume that the Fe-S cluster is required for protein stability. We further mutated conserved tyrosines that are located between the DNA lesion and the Fe-S cluster. Mutagenesis results showed that Tyr424 was essential for lesion binding and repair, and Tyr430 was required for efficient repair. The results point to an important function of highly conserved tyrosines in prokaryotic (6–4) photolyase

Structures of ribosome-bound initiation factor 2 reveal mechanism of subunit association

Throughout the four phases of protein biosynthesis—initiation, elongation, termination, and recycling—the ribosome is controlled and regulated by at least one specified translational guanosine triphosphatase (trGTPase). Although the structural basis for trGTPase interaction with the ribosome has been solved for the last three steps of translation, the high-resolution structure for the key initiation trGTPase, initiation factor 2 (IF2), complexed with the ribosome, remains elusive. We determine the structure of IF2 complexed with a nonhydrolyzable guanosine triphosphate analog and initiator fMet-tRNAiMet in the context of the Escherichia coli ribosome to 3.7-Å resolution using cryo-electron microscopy. The structural analysis reveals previously unseen intrinsic conformational modes of the 70S initiation complex, establishing the mutual interplay of IF2 and initator transfer RNA (tRNA) with the ribsosome and providing the structural foundation for a mechanistic understanding of the final steps of translation initiation

High frequency magnetic oscillations of the organic metal θ\theta-(ET)4_4ZnBr4_4(C6_6H4_4Cl2_2) in pulsed magnetic field of up to 81 T

De Haas-van Alphen oscillations of the organic metal $\theta$-(ET)$_4$ZnBr$_4$(C$_6$H$_4$Cl$_2$) are studied in pulsed magnetic fields up to 81 T. The long decay time of the pulse allows determining reliable field-dependent amplitudes of Fourier components with frequencies up to several kiloteslas. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits. In this model, all the observed frequencies are linear combinations of the frequency linked to the basic orbit $\alpha$ and to the magnetic-breakdown orbit $\beta$.Comment: 6 pages, 4 figure

Measurement Near Threshold of 9-Be(3-He, Pi) to the A = 12 Isobaric Triplet by Recoil Detection

This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

Molecular architecture of the ribosome-bound Hepatitis C Virus internal ribosomal entry site RNA

Internal ribosomal entry sites (IRESs) are structured cis‐acting RNAs that drive an alternative, cap‐independent translation initiation pathway. They are used by many viruses to hijack the translational machinery of the host cell. IRESs facilitate translation initiation by recruiting and actively manipulating the eukaryotic ribosome using only a subset of canonical initiation factor and IRES transacting factors. Here we present cryo‐EM reconstructions of the ribosome 80S‐ and 40S‐bound Hepatitis C Virus (HCV) IRES. The presence of four subpopulations for the 80S•HCV IRES complex reveals dynamic conformational modes of the complex. At a global resolution of 3.9 Å for the most stable complex, a derived atomic model reveals a complex fold of the IRES RNA and molecular details of its interaction with the ribosome. The comparison of obtained structures explains how a modular architecture facilitates mRNA loading and tRNA binding to the P‐site. This information provides the structural foundation for understanding the mechanism of HCV IRES RNA‐driven translation initiation

Ex-ante assessment of returns on research investments to address the impact of Fusarium Wilt tropical race 4 on global banana production

The spread of Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), causal agent of Fusarium wilt of banana (FWB), has been projected to reach 17% of the global banana-growing area by 2040 equaling 36 million tons of production worth over US$10 billion. This potential loss has fueled (inter)national discussions about the best responses to protect production and small-scale growers’ livelihoods. As part of a multi-crop ex ante assessment of returns on research investments conducted by the CGIAR Research Program on Roots, Tubers, and Bananas (RTB) from 2012 to 2016, four FWB research options were assessed: (i) improved exclusion, surveillance, eradication, and containment (ESEC) measures to reduce Foc TR4 spread, (ii) integrated crop and disease management (ICDM) to facilitate production of partially FWB resistant cultivars on Foc-infested soils, (iii) conventional breeding of FWB-resistant cultivars (CBRC), and (iv) genetically modified (GM) FWB-resistant cultivars (GMRC). Building on a risk index (Foc scale) predicting the initial occurrence and internal spread of Foc TR4 in 29 countries, an economic surplus (ES) model, cost-benefit analysis, and poverty impact simulations were used to assess impact under two adoption scenarios. All options yield positive net present values (NPVs) and internal rates of return (IRRs) above the standard 10% rate. For the conservative scenario with 50% reduced adoption, IRRs were still 30% for ICDM, 20% for CBRC, and 28% for GMRC. ESEC has IRRs between 11 and 14%, due to higher costs of capacity strengthening, on-going surveillance, farmer awareness campaigns, and implementation of farm biosecurity practices, which could be effective for other diseases and benefit multiple crops. The research investments would reach between 2.7 million (GMRC) and 14 million (ESEC) small-scale beneficiaries across Asia/Pacific, Sub-Saharan Africa, and Latin America/Caribbean. The options varied in their potential to reduce poverty, with the largest poverty reduction resulting from CBRC with 850,000 and ESEC with 807,000 persons lifted out of poverty (higher adoption scenario). In the discussion, we address the data needs for more fine-grained calculations to better guide research investment decisions. Our results show the potential of public investments in concerted research addressing the spread of Foc TR4 to yield high returns and substantially slow down disease spread