Littérature scientifique sur le sujet « ISC assembly machinery »
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Articles de revues sur le sujet "ISC assembly machinery"
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Vilella, Felipe, Rui Alves, María Teresa Rodríguez-Manzaneque, Gemma Bellí, Swarna Swaminathan, Per Sunnerhagen et Enrique Herrero. « Evolution and Cellular Function of Monothiol Glutaredoxins : Involvement in Iron-Sulphur Cluster Assembly ». Comparative and Functional Genomics 5, no 4 (2004) : 328–41. http://dx.doi.org/10.1002/cfg.406.
Texte intégralRésumé :
A number of bacterial species, mostly proteobacteria, possess monothiol glutaredoxins homologous to theSaccharomyces cerevisiaemitochondrial protein Grx5, which is involved in iron–sulphur cluster synthesis. Phylogenetic profiling is used to predict that bacterial monothiol glutaredoxins also participate in the iron–sulphur cluster (ISC) assembly machinery, because their phylogenetic profiles are similar to the profiles of the bacterial homologues of yeast ISC proteins. High evolutionary co-occurrence is observed between the Grx5 homologues and the homologues of the Yah1 ferredoxin, the scaffold proteins Isa1 and Isa2, the frataxin protein Yfh1 and the Nfu1 protein. This suggests that a specific functional interaction exists between these ISC machinery proteins. Physical interaction analyses using low-definition protein docking predict the formation of strong and specific complexes between Grx5 and several components of the yeast ISC machinery. Two-hybrid analysis has confirmed thein vivointeraction between Grx5 and Isa1. Sequence comparison techniques and cladistics indicate that the other two monothiol glutaredoxins ofS. cerevisiae, Grx3 and Grx4, have evolved from the fusion of a thioredoxin gene with a monothiol glutaredoxin gene early in the eukaryotic lineage, leading to differential functional specialization. While bacteria do not contain these chimaeric glutaredoxins, in many eukaryotic species Grx5 and Grx3/4-type monothiol glutaredoxins coexist in the cell.
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Camponeschi, Francesca, Simone Ciofi-Baffoni, Vito Calderone et Lucia Banci. « Molecular Basis of Rare Diseases Associated to the Maturation of Mitochondrial [4Fe-4S]-Containing Proteins ». Biomolecules 12, no 7 (21 juillet 2022) : 1009. http://dx.doi.org/10.3390/biom12071009.
Texte intégralRésumé :
The importance of mitochondria in mammalian cells is widely known. Several biochemical reactions and pathways take place within mitochondria: among them, there are those involving the biogenesis of the iron–sulfur (Fe-S) clusters. The latter are evolutionarily conserved, ubiquitous inorganic cofactors, performing a variety of functions, such as electron transport, enzymatic catalysis, DNA maintenance, and gene expression regulation. The synthesis and distribution of Fe-S clusters are strictly controlled cellular processes that involve several mitochondrial proteins that specifically interact each other to form a complex machinery (Iron Sulfur Cluster assembly machinery, ISC machinery hereafter). This machinery ensures the correct assembly of both [2Fe-2S] and [4Fe-4S] clusters and their insertion in the mitochondrial target proteins. The present review provides a structural and molecular overview of the rare diseases associated with the genes encoding for the accessory proteins of the ISC machinery (i.e., GLRX5, ISCA1, ISCA2, IBA57, FDX2, BOLA3, IND1 and NFU1) involved in the assembly and insertion of [4Fe-4S] clusters in mitochondrial proteins. The disease-related missense mutations were mapped on the 3D structures of these accessory proteins or of their protein complexes, and the possible impact that these mutations have on their specific activity/function in the frame of the mitochondrial [4Fe-4S] protein biogenesis is described.
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Wang, Jian, Carine Fillebeen, Guohua Chen, Annette Biederbick, Roland Lill et Kostas Pantopoulos. « Iron-Dependent Degradation of Apo-IRP1 by the Ubiquitin-Proteasome Pathway ». Molecular and Cellular Biology 27, no 7 (22 janvier 2007) : 2423–30. http://dx.doi.org/10.1128/mcb.01111-06.
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ABSTRACT Iron regulatory protein 1 (IRP1) controls the translation or stability of several mRNAs by binding to “iron-responsive elements” within their untranslated regions. In iron-replete cells, IRP1 assembles a cubane iron-sulfur cluster (ISC) that inhibits RNA-binding activity and converts the protein to cytosolic aconitase. We show that the constitutive IRP1C437S mutant, which fails to form an ISC, is destabilized by iron. Thus, exposure of H1299 cells to ferric ammonium citrate reduced the half-life of transfected IRP1C437S from ∼24 h to ∼10 h. The iron-dependent degradation of IRP1C437S involved ubiquitination, required ongoing transcription and translation, and could be efficiently blocked by the proteasomal inhibitors MG132 and lactacystin. Similar results were obtained with overexpressed wild-type IRP1, which predominated in the apo-form even in iron-loaded H1299 cells, possibly due to saturation of the ISC assembly machinery. Importantly, inhibition of ISC biogenesis in HeLa cells by small interfering RNA knockdown of the cysteine desulfurase Nfs1 sensitized endogenous IRP1 for iron-dependent degradation. Collectively, these data uncover a mechanism for the regulation of IRP1 abundance as a means to control its RNA-binding activity, when the ISC assembly pathway is impaired.
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Böttinger, Lena, Christoph U. Mårtensson, Jiyao Song, Nicole Zufall, Nils Wiedemann et Thomas Becker. « Respiratory chain supercomplexes associate with the cysteine desulfurase complex of the iron–sulfur cluster assembly machinery ». Molecular Biology of the Cell 29, no 7 (avril 2018) : 776–85. http://dx.doi.org/10.1091/mbc.e17-09-0555.
Texte intégralRésumé :
Mitochondria are the powerhouses of eukaryotic cells. The activity of the respiratory chain complexes generates a proton gradient across the inner membrane, which is used by the F1FO-ATP synthase to produce ATP for cellular metabolism. In baker’s yeast, Saccharomyces cerevisiae, the cytochrome bc1 complex (complex III) and cytochrome c oxidase (complex IV) associate in respiratory chain supercomplexes. Iron–sulfur clusters (ISC) form reactive centers of respiratory chain complexes. The assembly of ISC occurs in the mitochondrial matrix and is essential for cell viability. The cysteine desulfurase Nfs1 provides sulfur for ISC assembly and forms with partner proteins the ISC-biogenesis desulfurase complex (ISD complex). Here, we report an unexpected interaction of the active ISD complex with the cytochrome bc1 complex and cytochrome c oxidase. The individual deletion of complex III or complex IV blocks the association of the ISD complex with respiratory chain components. We conclude that the ISD complex binds selectively to respiratory chain supercomplexes. We propose that this molecular link contributes to coordination of iron–sulfur cluster formation with respiratory activity.
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Martens, Eric C., Joseph Gawronski-Salerno, Danielle L. Vokal, Molly C. Pellitteri, Megan L. Menard et Heidi Goodrich-Blair. « Xenorhabdus nematophila Requires an Intact iscRSUA-hscBA-fdx Operon To Colonize Steinernema carpocapsae Nematodes ». Journal of Bacteriology 185, no 12 (15 juin 2003) : 3678–82. http://dx.doi.org/10.1128/jb.185.12.3678-3682.2003.
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ABSTRACT An insertion between iscA and hscB of the Xenorhabdus nematophila iscRSUA-hscBA-fdx locus, predicted to encode Fe-S assembly machinery, prevented colonization of Steinernema carpocapsae nematodes. The insertion disrupted cotranscription of iscA and hscB, but did not reduce hscBA expression, suggesting that X. nematophila requires coordinated expression of the isc-hsc-fdx locus for colonization.
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Sheftel, Alex D., Claudia Wilbrecht, Oliver Stehling, Brigitte Niggemeyer, Hans-Peter Elsässer, Ulrich Mühlenhoff et Roland Lill. « The human mitochondrial ISCA1, ISCA2, and IBA57 proteins are required for [4Fe-4S] protein maturation ». Molecular Biology of the Cell 23, no 7 (avril 2012) : 1157–66. http://dx.doi.org/10.1091/mbc.e11-09-0772.
Texte intégralRésumé :
Members of the bacterial and mitochondrial iron–sulfur cluster (ISC) assembly machinery include the so-called A-type ISC proteins, which support the assembly of a subset of Fe/S apoproteins. The human genome encodes two A-type proteins, termed ISCA1 and ISCA2, which are related to Saccharomyces cerevisiae Isa1 and Isa2, respectively. An additional protein, Iba57, physically interacts with Isa1 and Isa2 in yeast. To test the cellular role of human ISCA1, ISCA2, and IBA57, HeLa cells were depleted for any of these proteins by RNA interference technology. Depleted cells contained massively swollen and enlarged mitochondria that were virtually devoid of cristae membranes, demonstrating the importance of these proteins for mitochondrial biogenesis. The activities of mitochondrial [4Fe-4S] proteins, including aconitase, respiratory complex I, and lipoic acid synthase, were diminished following depletion of the three proteins. In contrast, the mitochondrial [2Fe-2S] enzyme ferrochelatase and cellular heme content were unaffected. We further provide evidence against a localization and direct Fe/S protein maturation function of ISCA1 and ISCA2 in the cytosol. Taken together, our data suggest that ISCA1, ISCA2, and IBA57 are specifically involved in the maturation of mitochondrial [4Fe-4S] proteins functioning late in the ISC assembly pathway.
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Gomez-Casati, Diego F., Maria V. Busi, Julieta Barchiesi, Maria A. Pagani, Noelia S. Marchetti-Acosta et Agustina Terenzi. « Fe-S Protein Synthesis in Green Algae Mitochondria ». Plants 10, no 2 (21 janvier 2021) : 200. http://dx.doi.org/10.3390/plants10020200.
Texte intégralRésumé :
Iron and sulfur are two essential elements for all organisms. These elements form the Fe-S clusters that are present as cofactors in numerous proteins and protein complexes related to key processes in cells, such as respiration and photosynthesis, and participate in numerous enzymatic reactions. In photosynthetic organisms, the ISC and SUF Fe-S cluster synthesis pathways are located in organelles, mitochondria, and chloroplasts, respectively. There is also a third biosynthetic machinery in the cytosol (CIA) that is dependent on the mitochondria for its function. The genes and proteins that participate in these assembly pathways have been described mainly in bacteria, yeasts, humans, and recently in higher plants. However, little is known about the proteins that participate in these processes in algae. This review work is mainly focused on releasing the information on the existence of genes and proteins of green algae (chlorophytes) that could participate in the assembly process of Fe-S groups, especially in the mitochondrial ISC and CIA pathways.
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Lill, Roland, et Sven-A. Freibert. « Mechanisms of Mitochondrial Iron-Sulfur Protein Biogenesis ». Annual Review of Biochemistry 89, no 1 (20 juin 2020) : 471–99. http://dx.doi.org/10.1146/annurev-biochem-013118-111540.
Texte intégralRésumé :
Mitochondria are essential in most eukaryotes and are involved in numerous biological functions including ATP production, cofactor biosyntheses, apoptosis, lipid synthesis, and steroid metabolism. Work over the past two decades has uncovered the biogenesis of cellular iron-sulfur (Fe/S) proteins as the essential and minimal function of mitochondria. This process is catalyzed by the bacteria-derived iron-sulfur cluster assembly (ISC) machinery and has been dissected into three major steps: de novo synthesis of a [2Fe-2S] cluster on a scaffold protein; Hsp70 chaperone–mediated trafficking of the cluster and insertion into [2Fe-2S] target apoproteins; and catalytic conversion of the [2Fe-2S] into a [4Fe-4S] cluster and subsequent insertion into recipient apoproteins. ISC components of the first two steps are also required for biogenesis of numerous essential cytosolic and nuclear Fe/S proteins, explaining the essentiality of mitochondria. This review summarizes the molecular mechanisms underlying the ISC protein–mediated maturation of mitochondrial Fe/S proteins and the importance for human disease.
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Bandyopadhyay, Sibali, Kala Chandramouli et Michael K. Johnson. « Iron–sulfur cluster biosynthesis ». Biochemical Society Transactions 36, no 6 (19 novembre 2008) : 1112–19. http://dx.doi.org/10.1042/bst0361112.
Texte intégralRésumé :
Iron–sulfur (Fe–S) clusters are present in more than 200 different types of enzymes or proteins and constitute one of the most ancient, ubiquitous and structurally diverse classes of biological prosthetic groups. Hence the process of Fe–S cluster biosynthesis is essential to almost all forms of life and is remarkably conserved in prokaryotic and eukaryotic organisms. Three distinct types of Fe–S cluster assembly machinery have been established in bacteria, termed the NIF, ISC and SUF systems, and, in each case, the overall mechanism involves cysteine desulfurase-mediated assembly of transient clusters on scaffold proteins and subsequent transfer of pre-formed clusters to apo proteins. A molecular level understanding of the complex processes of Fe–S cluster assembly and transfer is now beginning to emerge from the combination of in vivo and in vitro approaches. The present review highlights recent developments in understanding the mechanism of Fe–S cluster assembly and transfer involving the ubiquitous U-type scaffold proteins and the potential roles of accessory proteins such as Nfu proteins and monothiol glutaredoxins in the assembly, storage or transfer of Fe–S clusters.
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Uzarska, Marta A., Rafal Dutkiewicz, Sven-Andreas Freibert, Roland Lill et Ulrich Mühlenhoff. « The mitochondrial Hsp70 chaperone Ssq1 facilitates Fe/S cluster transfer from Isu1 to Grx5 by complex formation ». Molecular Biology of the Cell 24, no 12 (15 juin 2013) : 1830–41. http://dx.doi.org/10.1091/mbc.e12-09-0644.
Texte intégralRésumé :
The mitochondrial Hsp70 chaperone Ssq1 plays a dedicated role in the maturation of iron–sulfur (Fe/S) proteins, an essential process of mitochondria. Similar to its bacterial orthologue HscA, Ssq1 binds to the scaffold protein Isu1, thereby facilitating dissociation of the newly synthesized Fe/S cluster on Isu1 and its transfer to target apoproteins. Here we use in vivo and in vitro approaches to show that Ssq1 also interacts with the monothiol glutaredoxin 5 (Grx5) at a binding site different from that of Isu1. Grx5 binding does not stimulate the ATPase activity of Ssq1 and is most pronounced for the ADP-bound form of Ssq1, which interacts with Isu1 most tightly. The vicinity of Isu1 and Grx5 on the Hsp70 chaperone facilitates rapid Fe/S cluster transfer from Isu1 to Grx5. Grx5 and its bound Fe/S cluster are required for maturation of all cellular Fe/S proteins, regardless of the type of bound Fe/S cofactor and subcellular localization. Hence Grx5 functions as a late-acting component of the core Fe/S cluster (ISC) assembly machinery linking the Fe/S cluster synthesis reaction on Isu1 with late assembly steps involving Fe/S cluster targeting to dedicated apoproteins.
Thèses sur le sujet "ISC assembly machinery"
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Adams, Azeez Olawale. « Control of reconfigurable assembly system ». Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5368.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This work considers the control of reconfigurable assembly systems using a welding assembly system as a case study. The assembly system consists of a pallet magazine, a feeding system, an inspection and removal system, a welding system and a conveyor. The aim of the work is to compare PC and PLC as controllers, as well as to compare two different approaches to reconfigurable control. The control system of the pallet magazine was developed using a PC and a PLC. The PC control was programmed using Visual C#, while the PLC was programmed in Ladder Logic using Siemens S-300 STEP7. The two controllers were compared based on the attributes that measure the quality of a controller's software, which include its capability, availability, usability and adaptability. The approaches to reconfigurable control considered were the agent-based methodology and the IEC 61499 distributed control methodology, both of which were applied to the feeding system. The agent-based control system was implemented using the JADE agent platform, while the IEC 61499 distributed control system was implemented using the FBDK software kit. These two methods were compared based on the characteristics of a reconfigurable system, which include the system's modularity, integrability, convertibility, diagnosability, customization and scalability. The result obtained in comparing the PC to the PLC shows that the PLC performs better in terms of capability, availability and usability, while the PC performs better in terms of adaptability. Also, the result of the comparison between the agent-based control system and the IEC 61499 distributed control system shows that the agent-based control system performs better in terms of integrability, diagnosability and scalability, while the IEC 61499 distributed control system performs better in terms of modularity and customization. They are, however, on a par in terms of convertibility.
AFRIKAANSE OPSOMMING: Hierdie werk beskou die beheer van herkonfigureerbare monteringstelsels met 'n sweismonteringstelsel as gevallestudie. Die monteringstelsel bestaan uit 'n paletmagasyn, 'n voerstelsel, 'n inspeksie-en- verwyderingstelsel, 'n sweisstelsel en 'n voerband. Die mikpunt van die werk is om persoonlike rekenaars (PCs) en programmeerbare-logikabeheerders (PLCs) as beheerders te vergelyk, asook om twee verskillende benaderings tot herkonfigureerbare beheer te vergelyk. Die beheerstelsel van die paletmagasyn is ontwikkel met 'n PC en 'n PLC. Die PC-beheer is in Visual C# geprogrammeer, terwyl die PLC in leerlogika met Siemens S-300 STEP7 geprogrammeer is. Die twee beheerders is vergelyk in terme van die eienskappe wat die kwaliteit van 'n beheerder se sagteware meet en sluit in vermoë, beskikbaarheid, bruikbaarheid en aanpasbaarheid. Die benaderings tot herkonfigureerbare beheer wat oorweeg is, is die agent-gebaseerde metodologie en die IEC 61499 verspreide-beheermetodologie. Beide is op die voerstelsel toegepas. Die agent-gebaseerde beheerstelsel is geïmplementeer met behulp van die JADE agent-platform, terwyl die IEC 61499 verspreide stelsel geïmplementeer is met behulp van die FBDK sagteware-stel. Hierdie twee metodes se vergelyking is gebaseer op die eienskappe van 'n herkonfigureerbare stelsel, waarby die stelsel se modulariteit, integreerbaarheid, diagnoseerbaarheid, pasmaakbaarheid en skaleerbaarheid ingesluit is. Die resultate wat in die vergelyking tussen die PC en PLC verkry is, toon dat die PLC beter vaar in terme van vermoë, beskikbaarheid en bruikbaarheid, terwyl die PC beter vaar in terme van aanpasbaarheid. Die resultaat van die vergelyking tussen die agent-gebaseerde beheerstelsel en die IEC 61499 verspreide beheerstelsel wys dat die agent-gebaseerde beheerstelsel beter vaar in terme van integreerbaarheid, diagnoseerbaarheid en skaleerbaarheid, terwyl die IEC 61499 verspreide beheerstelsel beter vaar in terme van modulariteit en pasmaakbaarheid. Hulle is egter vergelykbaar in terme van omskepbaarheid.
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Křoustek, Jakub. « Rekonfigurovatelná analýza strojového kódu ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-261276.
Texte intégralRésumé :
Analýza softwaru je metodologie, jejímž účelem je analyzovat chování daného programu. Jednotlivé metody této analýzy je možné využít i v dalších oborech, jako je zpětné inženýrství, migrace kódu apod. V této práci se zaměříme na analýzu strojového kódu, na zjištění nedostatků existujících metod a na návrh metod nových, které umožní rychlou a přesnou rekonfigurovatelnou analýzu kódu (tj. budou nezávislé na konkrétní cílové platformě). Zkoumány budou dva typy analýz - dynamická (tj. analýza za běhu aplikace) a statická (tj. analýza aplikace bez jejího spuštění). Přínos této práce v rámci dynamické analýzy je realizován jako rekonfigurovatelný ladicí nástroj a dále jako dva typy tzv. rekonfigurovatelného translátovaného simulátoru. Přínos v rámci statické analýzy spočívá v navržení a implementování rekonfigurovatelného zpětného překladače, který slouží pro transformaci strojového kódu zpět do vysokoúrovňové reprezentace. Všechny tyto nástroje jsou založeny na nových metodách navržených autorem této práce. Na základě experimentálních výsledků a ohlasů od uživatelů je možné usuzovat, že tyto nástroje jsou plně srovnatelné s existujícími (komerčními) nástroji a nezřídka dosahují i lepších výsledků.
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Saudino, Giovanni. « Protein expression and characterization for systems involved in the biogenesis of iron sulfur proteins ». Doctoral thesis, 2021. http://hdl.handle.net/2158/1251249.
Texte intégralRésumé :
Iron-sulfur clusters are essential cofactors found in all kingdoms of life; they had unique functional roles throughout evolution. These clusters, which are the second major form of complex iron cofactors in biology, are ubiquitous in all organisms, playing a key role in several biological pathways. Mutations on the protein involved in the iron-sulfur clusters biosynthesis pathway are associated with a group of multiple mitochondrial dysfunction syndromes (MMDS). These severe diseases could give infantile encephalopathy, lactic acidosis, leukodystrophy and death in early childhood. In human cells, cluster biosynthesis involves three different types of machinery: ISC (iron-sulfur cluster assembly machinery) located in the mitochondria, CIA (cytosolic iron-sulfur cluster assembly machinery) located in the cytosol and ISC export machinery located in the mitochondria inner membrane. The aim of the thesis was the deep investigation of the third step of the ISC assembly machinery. Indeed, using NMR, UV-vis and CD-vis spectroscopies in combination with size exclusion chromatography and multi-angle light scattering we assessed the key role of NFU1, ISCA1, ISCA2, FDX2 and LIAS in the above-mentioned machinery. Moreover, clinical BOLA3 Cys59Tyr mutation involved in the MMDS diseases has investigated at the atomistic and molecular levels. The gained data elucidated fundamental molecular details in the [4Fe-4S] cluster maturation and transfer to apo recipient proteins along the third step of ISC assembly machinery.
Livres sur le sujet "ISC assembly machinery"
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Ovtov, Vladimir. Machine parts. Course design. ru : INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1171976.
Texte intégralRésumé :
The textbook discusses the methodology of course design of general-purpose drives with a single-stage gearbox (cylindrical, conical and worm) and a V-belt or chain transmission. The procedure for calculating gears and constructing assembly drawings of gearboxes is shown, the development of specifications using the COMPASS-3D computer-aided design system is described. Examples of the design of drawings of the general type of the drive, assembly drawings of gearboxes and working drawings of parts of various types of gearboxes are given.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
It is intended for independent work of students of engineering specialties studying in the bachelor's degree and specialty.
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Strebkov, Sergey, et Andrey Sahnov. Machine repair technology. ru : INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1184662.
Texte intégralRésumé :
The tutorial discusses the technological processes of remontamashin, contains elements of the design of technological processes for the restoration of parts and assembly units, describes ways to restore the main defects of machine parts.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
It is intended for students in the direction of training 35.03.06 "Agroengineering".
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Ivanov, Anatoliy. Flexible modular assembly lines on a single structural basis. ru : INFRA-M Academic Publishing LLC., 2022. http://dx.doi.org/10.12737/1196558.
Texte intégralRésumé :
The textbook discusses topical issues of automating the assembly of an extensive range of machine and instrument-making products based on highly efficient robotic reconfigurable systems of a new generation built on a single structural basis. The possibility of fast organization of automated assembly of new types of products, which is provided by the presence of a flexible basic set as part of the complex (line), is shown. A complete set of original technical means for basic and service operations of assembly and control of products is described. Analytical conditions of automatic assembly are given, and recommendations on optimization of design solutions and modeling of projected assembly systems are given.
It is intended for students studying under the bachelor's degree programs, certified specialists and masters, teachers of technical universities, as well as designers, technologists and scientists dealing with the problem of complex assembly automation.
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Yurenkova, Lyubov', Viktor Burlay, Vladimir Fedorenko et Aleksey Andreev. Engineering graphics : Atlas of assembly units with different types of connections of parts. ru : INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/953403.
Texte intégralRésumé :
The tutorial contains drawings of assembly units with a description of their design. Special attention is paid to the analysis of the connections of the parts. Examples of assembly units containing a small number of parts are used to describe the most common types of connections in the designs of machines and devices out of several dozen currently known. The atlas will allow you to introduce students to various modern types of connections of parts in a short time during classes. Meets the requirements of the federal state educational standards of higher education of the latest generation. For students of higher educational institutions studying in an enlarged group of training areas 15.00.00 "Mechanical Engineering".
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Moses, Matthew S., et Gregory S. Chirikjian. Reproduction. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199674923.003.0007.
Texte intégralRésumé :
Computing pioneer and polymath John von Neumann introduced the concept of a Universal Constructor as part of his effort to develop a mathematical theory describing living organisms. A Universal Constructor is a kinematic machine able to manipulate and assemble primitive building blocks. Von Neumann showed how this hypothetical constructor, being itself composed of the same primitive blocks, could self-reproduce and evolve. Remarkably, although this model system pre-dates the discovery of the genetic code, it applies to cell molecular biology as well as man-made machines. This chapter describes some key laboratory demonstrations related to universal construction and machine self-reproduction, and discusses parallels between reproduction processes in machines and biological cells.
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International, IPC. IPC-HERMES-9852, Version 1.5 the Global Standard for Machine-To-Machine Communication in SMT Assembly. IPC International, 2022.
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Prescott, Tony J., Nathan Lepora et Paul F. M. J. Verschure, dir. Living machines. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199674923.001.0001.
Texte intégralRésumé :
Biomimetics is the development of novel technologies through the distillation of ideas from the study of biological systems. Biohybrids are formed through the combination of at least one biological component—an existing living system—and at least one artificial, newly engineered component. These two fields are united under the theme of Living Machines—the idea that we can construct artifacts that not only mimic life but also build on the same fundamental principles. The research described in this volume seeks to understand and emulate life’s ability to self-organize, metabolize, grow, and reproduce; to match the functions of living tissues and organs such as muscles, skin, eyes, ears, and neural circuits; to replicate cognitive and physical capacities such as perception, attention, locomotion, grasp, emotion, and consciousness; and to assemble all of these elements into integrated systems that can hold a technological mirror to life or that have the capacity to merge with it. We conclude with contributions from philosophers, ethicists, and futurists on the potential impacts of this remarkable research on society and on how we see ourselves.
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Fukuda, Toshio, Masahiro Nakajima, Masaru Takeuchi et Yasuhisa Hasegawa. Micro- and nanotechnology for living machines. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199674923.003.0052.
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The chapter Micro- and nanotechnology for living machines describes research on new biohybrid technologies, engineered at the micro- and nano-scales, that combine some of the benefits of mechanical and electronic systems with those of biological systems. The chapter begins by reviewing some of the challenges of building devices at very small physical scales and discusses how new fabrication methodologies could impact on different classes of industrial, daily life, and biomedical products. We next explain how progress is being achieved through advances in micro- and nanomechatronics, particularly in the field of nanorobotic manipulation. Finally, we summarize recent progress towards building biohybrid living machines that combine nanomaterials with biological cells and outline the design of a micro- and nanorobotic manipulation system for cell assembly called the nanolaboratory.
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Anderson, James A. Software. Oxford University Press, 2018. http://dx.doi.org/10.1093/acprof:oso/9780199357789.003.0004.
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Digital computers are “protean” in that they can become almost anything through software. Their basic design elements came from a 19th-century British tradition in logic, exemplified by Boole and Babbage. It seemed natural to have logic realized in hardware. This tradition culminated in the work of Alan Turing who proposed a universal computing machine, now called a Turing machine, based on logic. Although hardware that computes logic functions lies at the core of digital hardware, low-level practical machine operations are grouped together in “words.” Programs are based on hardware operations controlling computation at the word level. This chapter presents a detailed example of what a computer does when it actually “computes.” Because human cognition finds it hard to use such an alien device, there is a brief discussion of how programming became “humanized” with the invention of software tools like assembly language and FORTRAN.
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Little, Max A. Machine Learning for Signal Processing. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198714934.001.0001.
Texte intégralRésumé :
Digital signal processing (DSP) is one of the ‘foundational’ engineering topics of the modern world, without which technologies such the mobile phone, television, CD and MP3 players, WiFi and radar, would not be possible. A relative newcomer by comparison, statistical machine learning is the theoretical backbone of exciting technologies such as automatic techniques for car registration plate recognition, speech recognition, stock market prediction, defect detection on assembly lines, robot guidance and autonomous car navigation. Statistical machine learning exploits the analogy between intelligent information processing in biological brains and sophisticated statistical modelling and inference. DSP and statistical machine learning are of such wide importance to the knowledge economy that both have undergone rapid changes and seen radical improvements in scope and applicability. Both make use of key topics in applied mathematics such as probability and statistics, algebra, calculus, graphs and networks. Intimate formal links between the two subjects exist and because of this many overlaps exist between the two subjects that can be exploited to produce new DSP tools of surprising utility, highly suited to the contemporary world of pervasive digital sensors and high-powered and yet cheap, computing hardware. This book gives a solid mathematical foundation to, and details the key concepts and algorithms in, this important topic.
Chapitres de livres sur le sujet "ISC assembly machinery"
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Gilder, Jules H. « Machine Code or Assembly Language ». Dans Apple IIc and IIe Assembly Language, 3–4. Boston, MA : Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-6424-5_1.
Texte intégral
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Gilder, Jules H. « A Poke at Machine Code ». Dans Apple IIc and IIe Assembly Language, 22–30. Boston, MA : Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-6424-5_6.
Texte intégralActes de conférences sur le sujet "ISC assembly machinery"
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Wang, Mu-Chun, Zhen-Ying Hsieh, Kuo-Shu Huang, Shuang-Yuan Chen et Heng-Sheng Huang. « Investigation of Dicing Saw Methods Impacting Back-End Assembly Process ». Dans 2008 Second International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2008. http://dx.doi.org/10.1115/micronano2008-70015.
Texte intégralRésumé :
The chip size, substrate material and package type of ICs are continuously changed due to the advanced process development. In order to satisfy these needs, it is necessary to cut wafers as discrete chip shape. Recently, the cutting technology cardinally relies on the thinner diamond blade plus some variable dicing saw parameters to obtain the separate chips. Although the cutting process is similar to that with traditional mechanical cutting, the accuracy and the quality are totally different. The previous is better than the last. Therefore, the cutting cost is not easily reduced more, except promoting the cutting yield. At the same time, if the utility rate of the cutting machine in one day is increased, this is an alternative to possibly decrease the cost. In present and commercial species of cutting machine, there are single cut, double cut, and laser cut. Except some advanced products or special wafers with laser cut method, most of commercial ICs are still cut with single-cut machine. In this study, we investigate the recent wafer cutting methods and how to protect the pad quality on ICs and probably decrease the assembly price. During this effort, we expect that one is to increase the cutting yield and the other is to practically reduce the assembly-line cost.
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Malinin, Grigoriy, et S. Yankevich. « LOGIC AUTOMATIC DRIVER CONTROL IN THE SYSTEM OF CONTROL OF POWERFUL POWER CONVERTERS ». Dans CAD/EDA/SIMULATION IN MODERN ELECTRONICS 2019. Bryansk State Technical University, 2019. http://dx.doi.org/10.30987/conferencearticle_5e02821252ea43.36490574.
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The paper presents an analysis of possible emergency conditions in a voltage converter controlled from an FPGA or a microcontroller and a method for eliminating them using a logical machine. The principle of operation of the machine is explained using a model assembled in CAD Xilinx ISE Design Suite.
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Wang, Mu-Chun, Kuo-Shu Huang, Zhen-Ying Hsieh, Shuang-Yuan Chen et Heng-Sheng Huang. « Avoidance of Bonding Pad Contamination Affecting Back-End Assembly Process ». Dans 2008 Second International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2008. http://dx.doi.org/10.1115/micronano2008-70016.
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While the process fabrication and the electronic applications develop quickly, the die size and the package type also confront the improvement from the customers’ request to achieve the better signal performance in IC products. In cost consideration and marketing competition, most of commercial IC products still adopt the wire-bond technology, except some high performance products with solder/gold balls adhesion process. For consumer ICs, the gold wire is the major material to connect the IC chip and the lead frame through the bondability technology. In the recent era, the bond pad size and pitch is always shrinking. Therefore, the bond performance strongly depends on wire bond machine to provide lighters, thinner, and more reliable IC. After pad size shrinkage, the quality of pad is more impressed for wire bond reliability, especially in fine-pitch assembly process. It’s a challenge in reliability requirement. In this study, the root cause and promising solution of bond pad contamination were investigated. One is to improve the bonding yield in wire-bond process; the other is to promote the bonding reliability after the whole assembly process.
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Robeda, James, et Richard Morgan. « Evaluation of Machine-Vision Based Profile Measurements for Rolling Railcar Wheels ». Dans ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61890.
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In an effort to increase the number of wheels with measured profile parameters and reduce the number of condemnable wheels in service, machine vision-based wayside inspection systems are being developed to “virtually” gage all wheels of passing trains. In 2003, Transportation Technology Center, Inc. (TTCI), a wholly owned subsidiary of the Association of American Railroads (AAR), evaluated a pair of these wheel profile monitoring systems from two different vendors. Wheel-related expenses (inspection, maintenance, and replacement) make up about 37 percent of annual car maintenance costs. A significant portion of these expenses is directly related to maintenance actions associated with worn wheels. The primary indicators of worn wheels are wheel profile parameters that reach condemnable limits imposed by industry maintenance standards. These parameters include flange thickness, flange height, rim thickness, and tread hollow (hollow-worn wheels). To monitor profile parameters, inspectors attempt to visually check each wheel on inbound and outbound trains. They also measure wheel profile parameter values with steel gages on about 5 percent of the wheels annually. Each system TTCI evaluated used a different method to measure wheel profiles and determine the four primary parameters of interest. One system used lasers to highlight the wheel profile, and the other used high intensity strobes to take a picture of the wheel. Both systems used video frame capture technology and proprietary algorithms to analyze the data and calculate profile parameters. Both systems were installed at wayside locations at the Federal Railroad Administration’s Transportation Technology Center (TTC), Pueblo, Colorado. The systems were set up and evaluated over a period of several months. For each system evaluation, a test consist was assembled and run by the system at various speeds and lighting conditions. The profiles for test wheels were measured with a MiniProf® profilometer, and the four primary profile parameters were determined for each wheel prior to testing. Both systems were used during the tests to measure the wheel profiles and associated profile parameters. Through subsequent analysis, the system-derived parameters were compared to MiniProf parameter values for each test wheel to determine the tested system measurement accuracy. Both systems were found to be capable of delivering measurement accuracies of greater than 90 percent for three of the four parameters.
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Bourret, Quentin, Pierre-Olivier Lemieux, Julie Charland et Rachid Aissaoui. « Grasp Planning Of Unknown Object For Digital Human Model ». Dans 13th International Conference on Applied Human Factors and Ergonomics (AHFE 2022). AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1001908.
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ObjectiveGrasp planning is a popular topic in the fields of robotic and Digital Human Model (DHM) (4, 6, 7, 9, 10, 11). So far, the proposed planners do not consider the final posture of the DHM has a criteria when determining potential grasps. In (4), a grasping algorithm has been developed to automatically grasp known tools. The present work introduces a grasp planner for single-hand grasp on an unknown object, further referred as “part”.MethodThe grasp planner gives has a result a grasp pose (position + orientation) for the posture solver (Smart Posturing Engine) to reach. The input necessary to the grasp planner are the 3D model of the object to grasp and of the surrounding environment, and an initial manikin position that is automatically determines by the posture solver algorithm.First the part is approximated by its oriented bounding box (OBB), limiting the grasp poses to 6 (one for each face of the OBB). Then precise grasp types (5) and apertures are chosen based on the face’s dimensions (i.e. width and depth), ranging from a small face (i.e. pinch) to larger ones (i.e. medium wrap or precision sphere).To determine what is the best face of the OBB to grasp, accessibility checks are performed by validating that the space around the face is free of collision. The faces are checked using a specific order (i.e. top, right or left, bottom, front, back) that is determined using the relative initial position of the manikin. As soon as a face is found to be graspable and accessible, the algorithm stops and choose that face as the best one to grasp.Using the selected face target, the hand is positioned using an inverse kinematic solver, free to rotate around the target using extra hand degrees-of-freedom inside a limited range (4). Giving the posture solver more possibilities to find a realistic posture.ResultsThe grasp planner described above leaded to believable grasps for the simulated tasks as well as a believable overall DHM posture. Examples of postures will be shown on assembly tasks performed on a gearbox assembly line.DiscussionThe proposed grasp planner seems really promising. In its current form, it is most suitable for small parts and bigger ones well represented by their OBB. More complex and bigger parts may require further segmentation into multiple smaller sub-parts (9, 10), allowing to perform the proposed checks at more specific and believable locations on the object. This would allow to obtain grasps on a wider range of objects. The object weight is also important and is currently being added to grasp type selection. The present planner is used by the Smart Posture Engine (SPE) framework (1, 2 and 3) inside Dassault Systèmes application “Ergonomic Workplace Design”. With the Ergo4All (12) technology the SPE allows to assess and minimize ergonomic risks involved in simulated workplaces.1. Lemieux, P.-O., Barré, A., Hagemeister, N., Aissaoui, R.: Degrees of freedom coupling adapted to the upper limb of a digital human model. Int. J. Hum. Factors Model. Simul. 5(4), 314–337 (2017)2. Lemieux, P., Cauffiez,M., Barré, A., Hagemeister, N., Aissaoui, R.: A visual acuity constraint for digital human modeling. In: 4th Conference proceedings (2016)3. Zeighami, A., Lemieux, P., Charland, J., Hagemeister, N., Aissaoui, A.: Stepping behavior for stability control of a digital human model. ISB/ASB (2019)4. Bourret, Q., Lemieux, P., Hagemeister, N., Aissaoui, R.: Flexible hand posture for tools grasping. DHM (2019)5. FEIX, Thomas, ROMERO, Javier, SCHMIEDMAYER, Heinz-Bodo, et al. The grasp taxonomy of human grasp types. IEEE Transactions on human-machine systems, 2015, vol. 46, no 1, p. 66-77.6. BEKEY, George A., LIU, Huan, TOMOVIC, Rajko, et al. Knowledge-based control of grasping in robot hands using heuristics from human motor skills. IEEE Transactions on Robotics and Automation, 1993, vol. 9, no 6, p. 709-722.7. Holleman, C.; Kavraki, L.E.; A framework for using the workspace medial axis in PRM planners, in Proceedings 2000 ICRA. Millennium Conference. IEEE International Conference on Robotics and Automation. Symposia Proceedings (Cat. No. 00CH37065), IEEE, Vol 2, 2000, 1408-1413. https://doi.org/10.1109/ROBOT.2000.8447958. FEIX, Thomas, BULLOCK, Ian M., et DOLLAR, Aaron M. Analysis of human grasping behavior: Correlating tasks, objects and grasps. IEEE transactions on haptics, 2014, vol. 7, no 4, p. 430-4419. Díaz, C.; Puente, S.; Torres, F.; Grasping points for handle objects in a cooperative disassembly system, IFAC Proceedings Volumes, 40(2), 2007, 112-117. https://doi.org/10.3182/20070523-3-ES-4907.0002010. Miller, A.T., Knoop, S., Christensen, H.I. and Allen, P.K., Automatic grasp planning using shape primitives. in Robotics and Automation, 2003. Proceedings. ICRA'03. IEEE International Conference on, (2003), IEEE, 1824-1829.11. Goussous, Faisal Amer. Grasp planning for digital humans. The University of Iowa, 2007.12. Bourret, Quentin, et al. "Ergo4All: An Ergonomic Guid
Rapports d'organisations sur le sujet "ISC assembly machinery"
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Alonso-Robisco, Andrés, José Manuel Carbó et José Manuel Carbó. Machine Learning methods in climate finance : a systematic review. Madrid : Banco de España, février 2023. http://dx.doi.org/10.53479/29594.
Texte intégralRésumé :
Preventing the materialization of climate change is one of the main challenges of our time. The involvement of the financial sector is a fundamental pillar in this task, which has led to the emergence of a new field in the literature, climate finance. In turn, the use of Machine Learning (ML) as a tool to analyze climate finance is on the rise, due to the need to use big data to collect new climate-related information and model complex non-linear relationships. Considering the proliferation of articles in this field, and the potential for the use of ML, we propose a review of the academic literature to assess how ML is enabling climate finance to scale up. The main contribution of this paper is to provide a structure of application domains in a highly fragmented research field, aiming to spur further innovative work from ML experts. To pursue this objective, first we perform a systematic search of three scientific databases to assemble a corpus of relevant studies. Using topic modeling (Latent Dirichlet Allocation) we uncover representative thematic clusters. This allows us to statistically identify seven granular areas where ML is playing a significant role in climate finance literature: natural hazards, biodiversity, agricultural risk, carbon markets, energy economics, ESG factors & investing, and climate data. Second, we perform an analysis highlighting publication trends; and thirdly, we show a breakdown of ML methods applied by research area.
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Wilson, Thomas E., Avraham A. Levy et Tzvi Tzfira. Controlling Early Stages of DNA Repair for Gene-targeting Enhancement in Plants. United States Department of Agriculture, mars 2012. http://dx.doi.org/10.32747/2012.7697124.bard.
Texte intégralRésumé :
Gene targeting (GT) is a much needed technology as a tool for plant research and for the precise engineering of crop species. Recent advances in this field have shown that the presence of a DNA double-strand break (DSB) in a genomic locus is critical for the integration of an exogenous DNA molecule introduced into this locus. This integration can occur via either non-homologous end joining (NHEJ) into the break or homologous recombination (HR) between the broken genomic DNA and the introduced vector. A bottleneck for DNA integration via HR is the machinery responsible for homology search and strand invasion. Important proteins in this pathway are Rad51, Rad52 and Rad54. We proposed to combine our respective expertise: on the US side, in the design of zincfinger nucleases (ZFNs) for the induction of DNA DSBs at any desired genomic locus and in the integration of DNA molecules via NHEJ; and on the Israeli side in the HR events, downstream of the DSB, that lead to homology search and strand invasion. We sought to test three major pathways of targeted DNA integration: (i) integration by NHEJ into DSBs induced at desired sites by specially designed ZFNs; (ii) integration into DSBs induced at desired sites combined with the use of Rad51, Rad52 and Rad54 proteins to maximize the chances for efficient and precise HR-mediated vector insertion; (iii) stimulation of HR by Rad51, Rad52 and Rad54 in the absence of DSB induction. We also proposed to study the formation of dsT-DNA molecules during the transformation of plant cells. dsT-DNA molecules are an important substrate for HR and NHEJ-mediatedGT, yet the mode of their formation from single stranded T-DNA molecules is still obscure. In addition we sought to develop a system for assembly of multi-transgene binary vectors by using ZFNs. The latter may facilitate the production of binary vectors that may be ready for genome editing in transgenic plants. ZFNs were proposed for the induction of DSBs in genomic targets, namely, the FtsH2 gene whose loss of function can easily be identified in somatic tissues as white sectors, and the Cruciferin locus whose targeting by a GFP or RFP reporter vectors can give rise to fluorescent seeds. ZFNs were also proposed for the induction of DSBs in artificial targets and for assembly of multi-gene vectors. We finally sought to address two important cell types in terms of relevance to plant transformation, namely GT of germinal (egg) cells by floral dipping, and GT in somatic cells by root and leave transformation. To be successful, we made use of novel optimized expression cassettes that enable coexpression of all of the genes of interest (ZFNs and Rad genes) in the right tissues (egg or root cells) at the right time, namely when the GT vector is delivered into the cells. Methods were proposed for investigating the complementation of T-strands to dsDNA molecules in living plant cells. During the course of this research, we (i) designed, assembled and tested, in vitro, a pair of new ZFNs capable of targeting the Cruciferin gene, (ii) produced transgenic plants which expresses for ZFN monomers for targeting of the FtsH2 gene. Expression of these enzymes is controlled by constitutive or heat shock induced promoters, (iii) produced a large population of transgenic Arabidopsis lines in which mutated mGUS gene was incorporated into different genomic locations, (iv) designed a system for egg-cell-specific expression of ZFNs and RAD genes and initiate GT experiments, (v) demonstrated that we can achieve NHEJ-mediated gene replacement in plant cells (vi) developed a system for ZFN and homing endonuclease-mediated assembly of multigene plant transformation vectors and (vii) explored the mechanism of dsTDNA formation in plant cells. This work has substantially advanced our understanding of the mechanisms of DNA integration into plants and furthered the development of important new tools for GT in plants.
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Stern, David B., et Gadi Schuster. Manipulation of Gene Expression in the Chloroplast : Control of mRNA Stability and Transcription Termination. United States Department of Agriculture, décembre 1993. http://dx.doi.org/10.32747/1993.7568750.bard.
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Chloroplasts are the site of photosynthesis and of other essential biosynthetic activities in plant cells. Chloroplasts are semi-autonomous organelles, since they contain their own genomes and protein biosynthetic machinery, but depend on the coordinate expression of nuclear genes to assemble macromolecular complexes. The bioeingineering of plants requires manipulation of chloroplast gene expression, and thus a knowledge of the molecular mechanisms that modulate mRNA and protein production. In this proposal the heterotrophic green alga Chlamydomonas reinhardtii has been used as a model system to understand the control and interrelationships between transcription termination, mRNA 3' end processing and mRNA stability in chloroplasts. Chlamydomonas is a unique and ideal system in which to address these issues, because the chloroplast can be easily manipulated by genetic transformation techniques. This research uncovered new and important information on chloroplast mRNA 3' end formation and mRNA stability. In particular, the 3' untranslated regions of chloroplast mRNAs were shown not to be efficient transcription terminators. The endonucleolytic site in the 3' untranslated region was characterized by site directed mutagensis and the role of several 3' untranslated regions in modulating RNA stability and translation has been studied. This information will allow us to experimentally manipulate the expression of chloroplast genes in vivo by post-transcriptional mechanisms, and should be widely applicable to other higher plant systems.
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Patel, Yusef. File to Factory : A case study of automated prefabrication house-building methods for small-to-medium enterprises. Unitec ePress, décembre 2017. http://dx.doi.org/10.34074/ocds.0823.
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The Eco-Digital Fabrication (EDFAB) research project aimed to investigate how automated prefabrication technologies and off-the-shelf construction products can be employed to disrupt building industry norms. The aim of this research – conducted at the University of Auckland and Unitec Institute of Technology from 2014 onward – was to provide small-to-medium enterprises in the construction industry with a pathway to upskill and increase construction productivity through the use of these processes. The availability of automated machines and easy-to-use fabrication software is increasing dramatically and this can be paired with readily available construction products to produce novel mass-customised housing solutions. The application of basic automated technologies – such as CNC (Computer Numerical Control) routers – allowed researchers to create ‘recipes’ that can be adopted and adapted relatively easily. By no means did the research favour digital manufacture or assembly processes over traditional analogue construction techniques – the goal was to provide logical, productive and accessible blended solutions for greater affordability and flexibility in design. For example, the designed experiments were required to be built from readily available products, and used simple readymade screw fixings rather than digitally produced custom fixings or joining mechanisms. The research project aimed to generate discussion and provide recommendations on how the construction industry might support the adoption of automated prefabrication technology in small-to-medium enterprise (SME).
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Bar-Joseph, Moshe, William O. Dawson et Munir Mawassi. Role of Defective RNAs in Citrus Tristeza Virus Diseases. United States Department of Agriculture, septembre 2000. http://dx.doi.org/10.32747/2000.7575279.bard.
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This program focused on citrus tristeza virus (CTV), the largest and one of the most complex RNA-plant-viruses. The economic importance of this virus to the US and Israeli citrus industries, its uniqueness among RNA viruses and the possibility to tame the virus and eventually turn it into a useful tool for the protection and genetic improvement of citrus trees justify these continued efforts. Although the overall goal of this project was to study the role(s) of CTV associated defective (d)-RNAs in CTV-induced diseases, considerable research efforts had to be devoted to the engineering of the helper virus which provides the machinery to allow dRNA replication. Considerable progress was made through three main lines of complementary studies. For the first time, the generation of an engineered CTV genetic system that is capable of infecting citrus plants with in vitro modified virus was achieved. Considering that this RNA virus consists of a 20 kb genome, much larger than any other previously developed similar genetic system, completing this goal was an extremely difficult task that was accomplished by the effective collaboration and complementarity of both partners. Other full-length genomic CTV isolates were sequenced and populations examined, resulting in a new level of understanding of population complexities and dynamics in the US and Israel. In addition, this project has now considerably advanced our understanding and ability to manipulate dRNAs, a new class of genetic elements of closteroviruses, which were first found in the Israeli VT isolate and later shown to be omnipresent in CTV populations. We have characterized additional natural dRNAs and have shown that production of subgenomic mRNAs can be involved in the generation of dRNAs. We have molecularly cloned natural dRNAs and directly inoculated citrus plants with 35S-cDNA constructs and have shown that specific dRNAs are correlated with specific disease symptoms. Systems to examine dRNA replication in protoplasts were developed and the requirements for dRNA replication were defined. Several artificial dRNAs that replicate efficiently with a helper virus were created from infectious full-genomic cDNAs. Elements that allow the specific replication of dRNAs by heterologous helper viruses also were defined. The T36-derived dRNAs were replicated efficiently by a range of different wild CTV isolates and hybrid dRNAs with heterologous termini are efficiently replicated with T36 as helper. In addition we found: 1) All CTV genes except of the p6 gene product from the conserved signature block of the Closteroviridae are obligate for assembly, infectivity, and serial protoplast passage; 2) The p20 protein is a major component of the amorphous inclusion bodies of infected cells; and 3) Novel 5'-Co-terminal RNAs in CTV infected cells were characterized. These results have considerably advanced our basic understanding of the molecular biology of CTV and CTV-dRNAs and form the platform for the future manipulation of this complicated virus. As a result of these developments, the way is now open to turn constructs of this viral plant pathogen into new tools for protecting citrus against severe CTV terms and development of virus-based expression vectors for other citrus improvement needs. In conclusion, this research program has accomplished two main interconnected missions, the collection of basic information on the molecular and biological characteristics of the virus and its associated dRNAs toward development of management strategies against severe diseases caused by the virus and building of novel research tools to improve citrus varieties. Reaching these goals will allow us to advance this project to a new phase of turning the virus from a pathogen to an ally.