• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 16
  • 15
  • 7
  • 5
  • 4
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 72
  • 14
  • 12
  • 8
  • 8
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

MPLS kontra traditionell IP-routing : en jämförelse av resursåtgång

Öhlin, Anton, Viking, Sebastian January 2011 (has links)
Multi Protocol Label Switching (MPLS) är en routingteknik som blir allt vanligare i dagens nätverk. Vid implementation av MPLS i nätverk är det grundläggande att hårdvaran har tillräckligt hög prestanda för att hantera tekniken. Om så inte är fallet kan det leda till negativa konsekvenser såsom paketförluster eller i värsta fall att routern havererar. Syftet med arbetet var att ta reda på hur processorbelastningen på en router skiljer sig när MPLS var implementerat jämfört med traditionell IP-routing. Routingprotokollen BGP, OSPF och RIP användes tillsammans med de olika routingteknikerna för att se vilket av dessa som krävde minst processorkraft. För att ta reda på hur processorbelastningen påverkades skapades en experimentmiljö. Varje routingprotokoll konfigurerades tillsammans med MPLS respektive traditionell IP-routing, vilket gav oss sex olika scenarion. Trafik skickades sedan genom nätverket med hjälp av applikationen Ostinato för att belasta enheterna. Resultatet av testerna visade att processorbelastningen blev högre för MPLS än för traditionell IP-routing. Det gällde för samtliga routingprotokoll. Det routingprotokoll som tillsammans med MPLS lyckades hålla processorbealstningen lägst var BGP, medans OSPF orsakade högst processorbelastning. Skillnaden mellan routingprotokollen OSPF och RIP var marginell. / Multi Protocol Label Switching (MPLS) is a growing routing technology. It is getting more common in today’s modern networks. When implementing MPLS, it is essential that the hardware is capable of handling such technology. If not, this could lead to packet loss or even network outage. The purpose of this study was to examine differences between MPLS and traditional IP-routing in aspect of CPU utilization. Routing protocols BGP, OSPF and RIP were configured together with the technologies in order to see which of the mentioned routing protocols that was the most efficient in terms of CPU utilization. An environment was created for the experiment. Each routing protocol was configured together with MPLS and traditional IP-routing respectively, which lead to a total of six scenarios. Traffic was sent through the network with an application called Ostinato with the purpose of increasing the load of the devices. The results showed higher CPU utilization with MPLS compared to traditional IP-routing. This was the case with each routing protocol. BGP had the lowest CPU utilization of the routing protocols in conjunction with MPLS whilst OSPF had the highest. The result between OSPF and RIP was slightly different.
22

Thermal and Electrical Degradation of Resin Impregnated Paper Insulation for High Voltage Transformer Bushings

Jyothi, N S January 2014 (has links) (PDF)
The overall reliability of a power transformer depends to a great extent on the sound operation of the bushings thereof. In view of its overwhelming advantages, resin impregnated paper (RIP) is acquiring prominence over conventional oil impregnated paper (OIP) in transformer bushings. The main advantages of RIP bushings are low dielectric loss and capability of positioning them at any desired angle over the transformer. The RIP structure, being an all-solid system, is completely free from oil phase. The temperature rise in RIP bushings under normal operating conditions is seen to be a difficult parameter to control in view of the limited options for effective cooling. The degradation of dry-type insulation such as RIP is often due to thermal and electrical stresses. The long time performance thereof, depends strongly, on the maximum operating temperature. In order to be able to predict the regional temperature, it is necessary to consider the thermal and electrical parameters of insulation in question; and to identify and solve the governing equations under the relevant boundary conditions. Electrical failure of insulation is known to be an extremal random process wherein nominally identical specimens of equipment insulation, at constant stress fails at inordinately different times. In order to be able to estimate the life of power equipment like transformer bushing, it is necessary to run long duration ageing experiments under accelerated stresses, to acquire and analyze insulation specific failure data. The present work is an attempt to provide reliability and life estimation of High Voltage RIP bushing insulation. The literature survey carried out in this view indicate that investigation on thermal and electric field distribution and the models for failure under combined stress and analysis of the data so as to be able to estimate the possible life of RIP bushing is scanty. Having these aspects in focus, the scope of the present work is defined as: (i) Mapping of the temperature and electric field distribution in the body of 400kV RIP bushing (ii) Deduction of parameters of the probabilistic models for the failure under electrical and thermal ageing (iii) Estimation of life based on diagnostic testing using PD With this in view, the temperature distribution in the body of a 400kV RIP bushing is studied considering the heat generation both in central conductor and that in the insulation. Presence of multiple materials with non-confirming interfaces makes analytical solution rather difficult and hence numerical approach is adopted. In the present work, vertex-centered Finite Volume Method (FVM) is employed for both thermal and electrical analysis. The electric stress distribution is accurately evaluated considering both the non-zero conductivity of the RIP material and the presence of capacitive grading foils. These analysis has clearly shown that Stress grading foils uniforms the stress across the major portion of the bushing insulation Enhancement of the electric conductivity by the temperature is not found to be affective in changing the electric field distribution The temperature distribution is shown to have a maxima near the flange due to the influence of top oil temperature of the transformer Heat generated in the dielectric due to the prevailing electric stress is shown to be insignificant. This ruled out the possibility of thermal runaway and hence the dielectric temperature is within the safe working limits for the bushing considered. The deduction of physical models governing insulation failure depends on the nature of stress. In this work, the insulation failure at constant accelerated stress has been considered and the estimation of life is computed based on inverse power law coupled with Arrhenius law. A high degree of scatter is generic to the experimental data forming the ingredients to develop the models. In view of this, the concept of a random process is invoked. Probabilistic models for the failure of RIP bushing under synergy are adopted and an attempt is made to estimate the life. The well known Weibull distribution and probability plotting of life data is used in this endeavor. The maximum likelihood estimation is used to determine the scale and shape parameters of the Weibull distribution. In the diagnosis of the extent of degradation of insulation due to PD, under long duration electric stress, a non-conventional voltage application method called the classical stepped stress method is adopted. In this technique, the voltage is applied in pre-determined steps over predetermined duration of time. The magnitude of voltage steps is carefully computed based on Miners law and the end-of-life is computed using inverse power law. In summary, this thesis work has contributed to the thermal and electrical degradation of resin impregnated paper insulation for high voltage transformer bushing. The thermal and electrical field distributions computed in the body of bushing clearly shown that these stresses are well within the limit, thereby ruling out the possibility of a thermal runaway. Comparing the estimates of the most probable life of RIP, based on several methods appears to show that any of the method can be adopted. However, as matter of caution and safety, the lowest among them can be taken as a reasonable estimate.
23

Identificação e caracterização de elementos transponíveis da classe II em Colletotrichum graminicola / Identification and characterization of class II transposable elements in Colletotrichum graminicola

Braga, Raíssa Mesquita 31 January 2012 (has links)
Made available in DSpace on 2015-03-26T13:51:56Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1477917 bytes, checksum: 4ab8f5cc2dd481acd067b02bd7abf32d (MD5) Previous issue date: 2012-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Colletotrichum is one of the most important genera of plant-pathogenic fungi in the world. The pathogenic species of this genus have hemibiotrophic lifestyle and cause diseases in several economically significant crops. Besides the economic importance, Colletotrichum has great significance as a model system for studying the molecular and cellular bases of fungal pathogenicity. The species C. graminicola, causal agent of corn anthracnose (Zea mays), has rare sexual stage and was the first species of the genus to have its genome completely sequenced. The transposable elements are ubiquitous and constitute a source of new mutations, being an important source of genetic variability. These elements are divided into two classes according to the presence or absence of an RNA intermediate in transposition. Elements of class I transpose via RNA intermediate, while class II elements transpose directly as DNA. The transposable elements can be applied as mutagenic agents aimed at the identification and labeling of genes and in phylogenetic and population studies. Given the importance of transposable elements in the generation of genetic variability and its applications in research, the aim of this study was to identify and characterize the class II transposable elements in the genome of C. graminicola. For this purpose, we used a bioinformatic approach combined with experimental activities. We identified 132 complete sequences of transposable elements in the sequenced genome of C. graminicola, which represent a significant proportion of the genome (0.47%). The elements were classified into six families according to similarity, all elements have characteristics of Tc1-mariner superfamily. Although some of these elements possess putative transposases with conserved DDE domain, all are interrupted by multiple stop codons. None of the elements identified has all the necessary features to be considered an active element. In silico analysis revealed evidence that these sequences are mutated by RIP (repeat point induced mutation) mechanism. TCg1 element was amplified by PCR from a Brazilian isolate and has imperfect terminal inverted repeats and the putative transposase sequence has three conserved domains characteristic of transposases: DDE, CENPB and HTH. However, this sequence is interrupted by stop codons and lacks the initiation codon and termination codon, therefore, is probably inactive. The genomic DNA from 49 different isolates were analyzed by hybridization with a probe derived from the inner region of TCg1 and different profiles were identified. The strategy allowed the efficient identification of a variety of Tc1-Mariner transposable elements degenerated by mutations characteristics of RIP in C. graminicola. It is unlikely that any of the identified elements is autonomous, however, these elements must have an important role in the genetic variability of this fungus. The TCg1 element is present in the genomes of different isolates of C. graminicola and has the potential to be used as a molecular marker in population analyzes. / Colletotrichum é um dos gêneros mais importantes de fungos fitopatogênicos em todo o mundo. As espécies fitopatogênicas desse gênero apresentam ciclo de vida hemibiotrófico e causam doenças em diversas culturas economicamente importantes. Além da importância econômica, Colletotrichum possui grande relevância como um sistema modelo para o estudo das bases celulares e moleculares da patogenicidade fúngica. A espécie Colletotrichum graminicola, agente causal da antracnose do milho (Zea mays), possui ciclo sexual raro e foi a primeira espécie do gênero a ter o seu genoma completamente sequenciado. Os elementos transponíveis são ubíquos e constituem uma fonte de novas mutações, sendo, portanto, uma importante fonte de variabilidade genética. Esses elementos são divididos em duas classes de acordo com a presença ou ausência de um intermediário de RNA na transposição. Os elementos da classe I se transpõem via intermediário de RNA, enquanto os elementos da classe II se transpõem diretamente como DNA. Os elementos transponíveis podem ser utilizados como agentes mutagênicos visando à identificação e etiquetagem de genes e em estudos filogenéticos e populacionais. Tendo em vista a importância dos elementos transponíveis na geração de variabilidade genética e as suas aplicações na pesquisa, o objetivo deste trabalho foi identificar e caracterizar elementos transponíveis da classe II no genoma de C. graminicola. Para tanto, foi utilizada uma abordagem de bioinformática (análises in silico) aliada às atividades experimentais. Foram identificadas 133 sequências completas de elementos transponíveis no genoma sequenciado de C. graminicola, que representam uma proporção relevante do genoma (0,47%). Os elementos foram classificados em 6 famílias de acordo com a identidade e apresentam características da superfamília Tc1-Mariner. Apesar de algumas transposases putativas codificadas por esses elementos possuírem domínio DDE conservado, todas estão interrompidas por vários códons de parada. Nenhum elemento identificado possui todas as características necessárias para um elemento autônomo. A análise in silico revelou evidências de mutações geradas pelo mecanismo de RIP (Mutação de ponto induzida por repetição). O elemento TCg1, amplificado por PCR a partir de um isolado brasileiro de C. graminicola, possui extremidades repetidas invertidas imperfeitas e a sequência putativa da transposase apresenta os três domínios característicos conservados: DDE, HTH e CENPB. Entretanto, essa sequência está interrompida por códons de parada e não foram localizados os códons de iniciação e de terminação, sendo, portanto, provavelmente inativa. O DNA genômico de 49 diferentes isolados foi analisado por hibridização com uma sequência derivada da região interna de TCg1 e apresentaram diferentes perfis. A estratégia utilizada permitiu uma identificação eficiente de uma variedade de elementos transponíveis Tc1-Mariner degenerados por mutações características de RIP em C. graminicola. É improvável que algum dos elementos identificados seja autônomo, entretanto, esses elementos devem possuir um importante papel na variabilidade genética desse fungo. O elemento TCg1 está presente no genoma de diferentes isolados de C. graminicola e possui potencial para ser utilizado como marcador molecular em análises populacionais.
24

Understanding the relationship of lumber yield and cutting bill requirements: a statistical approach

Buehlmann, Urs 13 October 1998 (has links)
Secondary hardwood products manufacturers have been placing heavy emphasis on lumber yield improvements in recent years. More attention has been on lumber grade and cutting technology rather than cutting bill design. However, understanding the underlying physical phenomena of cutting bill requirements and yield is essential to improve lumber yield in rough mills. This understanding could also be helpful in constructing a novel lumber yield estimation model. The purpose of this study was to advance the understanding of the phenomena relating cutting bill requirements and yield. The scientific knowledge gained was used to describe and quantify the effect of part length, width, and quantity on yield. Based on this knowledge, a statistics based approach to the lumber yield estimation problem was undertaken. Rip-first rough mill simulation techniques and statistical methods were used to attain the study's goals. To facilitate the statistical analysis of the relationship of cutting bill requirements and lumber yield, a theoretical concept, called cutting bill part groups, was developed. Part groups are a standardized way to describe cutting bill requirements. All parts required by a cutting bill are clustered within 20 individual groups according to their size. Each group's midpoint is the representative part size for all parts falling within an individual group. These groups are made such that the error from clustering is minimized. This concept allowed a decrease in the number of possible factors to account for in the analysis of the cutting bill requirements - lumber yield relationship. Validation of the concept revealed that the average error due to clustering parts is 1.82 percent absolute yield. An orthogonal, 220-11 fractional factorial design of resolution V was then used to determine the contribution of different part sizes to lumber yield. All 20 part sizes and 113 of a total of 190 unique secondary interactions were found to be significant (a = 0.05) in explaining the variability in yield observed. Parameter estimates of the part sizes and the secondary interactions were then used to specify the average yield contribution of each variable. Parts with size 17.50 inches in length and 2.50 inches in width were found to contribute the most to higher yield. The positive effect on yield due to parts smaller than 17.50 by 2.50 inches is less pronounced because their quantity is relatively small in an average cutting bill. Parts with size 72.50 by 4.25 inches, on the other hand, had the most negative influence on high yield. However, as further analysis showed, not only the individual parts required by a cutting bill, but also their interaction determines yield. By adding a sufficiently large number of smaller parts to a cutting bill that requires large parts to be cut, high levels of yield can be achieved. A novel yield estimation model using linear least squares techniques was derived based on the data from the fractional factorial design. This model estimates expected yield based on part quantities required by a standardized cutting bill. The final model contained all 20 part groups and their 190 unique secondary interactions. The adjusted R2 for this model was found to be 0.94. The model estimated 450 of the 512 standardized cutting bills used for its derivation to within one percent absolute yield. Standardized cutting bills, whose yield level differs by more than two percent can thus be classified correctly in 88 percent of the cases. Standardized cutting bills whose part quantities were tested beyond the established framework, i.e. the settings used for the data derivation, were estimated with an average error of 2.19 percent absolute yield. Despite the error observed, the model ranked the cutting bills as to their yield level quite accurately. However, cutting bills from actual rough mill operations, which were well beyond the framework of the model, were found to have an average estimation error of 7.62 percent. Nonetheless, the model classified four out of five cutting bills correctly as to their ranking of the yield level achieved. The least squares estimation model thus is a helpful tool in ranking cutting bills for their expected yield level. Overall, the model performs well for standardized cutting bills, but more work is needed to make the model generally applicable for cutting bills whose requirements are beyond the framework established in this study. / Ph. D.
25

Virtual Routing and Forwarding (VRF) - och dess påverkan på en routers processor

Ohlson, Johan January 2010 (has links)
<p>I dagsläget används VPN allt mer bland företagen för att ansluta till olika nätverk. Detta kan medföra att routingtabellen blir alltför stor och det kan i sin tur påverka processorbelastningen på routern som delar ut alla VPN.Detta arbete hade som syfte att granska om det är några märkbara prestandaskillnader på en routers processor när olika routingprotokoll används tillsammans med VRF. Protokollen som detta arbete tog upp var BGP, OSPF och RIP.Tre olika nätverks-scenarier skapades där olika tester genomfördes för de tre nämnda routingprotokollen. Det gjordes även tester på routrar när ingen VRF användes för att jämföra resultaten. Testerna bestod av att granska processorbelastningen på routrar när det fanns många rutter i nätverket och när nätverket var belastat med trafik.Testernas visade att skillnaden mellan BGP och OSPF inte är särskilt stor, men när RIP användes så steg processorbelastningen markant när nätverket hade många rutter. Om däremot VRF användes tillsammans med RIP så sjönk belastningen avsevärt på vissa routrar.</p>
26

Dune erosion, mega-cusps and rip currents modeling of field data

Keefer, Thomas B. 09 1900 (has links)
Sand dune erosion is highly episodic occurring only when storm waves coincide with high tides generating swash that impacts the toe of the dune. Owing to the episodic nature of sand dune erosion, it is difficult to observe in nature. The removal of a structure and rip-rap sea-wall from the Stilwell Hall site located in southern Monterey Bay provided a unique opportunity to study erosion processes at an accelerated rate. A 1-D wave impact line erosion model (Larson et al., 2004) was tested against data acquired at this site between April, 2004 and April 2005. The model was optimally tuned to the data by a dimensionless coefficient that relates the impact force to the rate of recession. The coefficient values ranged from 0.7-1.3x10-3, for this field data, compared with values of 1.0-2.5x10-3 previously obtained for lab and field data. Migrating rip currents create a system of mega-cusps, which are nominally 10m in width and 200m in alongshore wavelength (Thornton, 2005). The presence of megacusps is hypothesized to accelerate sand dune erosion at their embayments where the beach is steeper and narrowest (Short, 1979;Shih and Komar, 1984;Revell, et al., 2002). It was determined that the highest recession occurred at the location of the rip current/mega-cusp embayment. Changes in the surf climate are of great interest to Naval Special Warfare (NSW) and U.S. Marine Corps (USMC) forces tasked with planning and executing operations in littoral areas. Naval history is replete with operations highlighting the importance of understanding and accurate prediction of nearshore dynamics. Without the ability to predict nearshore morphologic processes, providing such support is impossible.
27

Synthèse et caractérisation de réseaux semi-interpénétrés de polymères à base de polyisobutène linéaire / Synthesis and caracterizations of linear polyisobutene based semi-interpenetrating networks

Davion, Benjamin 08 December 2010 (has links)
De nouveaux matériaux à base de polyisobutène (PIB) linéaire non fonctionnel ont été élaborés dans l'objectif d'élargir les domaines d'application des polyisobutènes de masses molaires intermédiaires (10 000 < Mn < 100 000 g.mol-1), actuellement peu exploités.Une architecture de type réseau semi-interpénétré de polymères (semi-RIP) a été choisie pour immobiliser physiquement le PIB linéaire au sein de divers réseaux polyméthacrylate. Les précurseurs (monomère, réticulant et amorceur) des réseaux solubilisant le PIB, les synthèses sont réalisées sans solvant et le programme thermique a été optimisé. Des semi-RIPs homogènes macroscopiquement et ne fluant pas sont obtenus pour des proportions massiques de PIB comprises entre 20 et 70%. Les analyses thermomécaniques ont montré que ces semi-RIPs présentent une morphologie de phases co-continues. La modification de la nature et de la composition du co-réseau partenaire permet de moduler « à façon » les propriétés mécaniques (module de conservation et facteur de perte) de ces semi-RIPs entre -10 et 200°C tout en conservant certaines propriétés du PIB (imperméabilité aux gaz).Enfin, une relaxation mécanique haute température intervenant au-delà des Tgs des deux polymères associés a été détectée dans la plupart des semi-RIPs PIB/polyméthacrylate étudiés. Une interprétation de l'origine de cette relaxation mécanique a été proposée. / New linear and non functional polyisobutene (PIB) based materials have been synthesized to enlarge the potential application of medium molecular weight polyisobutènes (10 000 < Mn < 100 000 g.mol-1), currently underemployed.A semi-interpenetrating polymer network (semi-IPN) architecture have been employed to immobilize the linear PIB chains physically inside different polymethacrylate networks. The networks precursors (monomer, cross-linker and initiator) are miscible with PIB and syntheses without solvent have been carried out, and thermal curing has been optimized. Macroscopically homogeneous semi-IPNs showing no creep, for PIB weight proportions from 20 to 70%, have been obtained. Thermomechanical analyses of semi-IPNs shown co-continuous phase morphology. By changing the nature and composition of the partner co-network, the mechanical properties (storage modulus and damping factor) of the semi-IPNs are tunable between -10 and 200°C, while some properties of the PIB (very low permeation to gases) are kept.Finally, the semi-IPN architecture and the chosen synthesis pathway, among other things, lead to the observation of a high temperature relaxation above the Tg of both associated polymers, in almost all of the studied semi-IPNs. An interpretation of the origin of this phenomenon has been proposed.
28

The Development and Application of a Method to Quantitatively Identify RNA Binding Sites, and Whole Transcript Targets of RNA Binding Proteins

Nicholson, Cindo Oliver January 2016 (has links)
<p>RNA binding proteins (RBPs) and non-coding RNAs orchestrate gene expression in part through the recognition specific sites in mRNA. Thus understanding the connection between binding to specific sites and regulation of the whole transcript is essential. Current methods to do this can either identify the binding sites or quantitate binding to whole transcripts, but not both. Furthermore reliance of binding site detection on ultraviolet crosslinking results in inefficient identification of binding sites, and insufficient data to assess binding strength at sites. I have overcome these limitations by combining aspects of current methods to develop a new method called DO-RIP-seq (digestion optimization RNA immunoprecipitations with deep sequencing) that can quantitate the binding strength of RBPs at sites in mRNA, and also relate binding sites to binding of the whole mRNA. DO-RIP-seq was developed using the well-studied RBP ELAVL1/HuR as a test case, and applied to the less well-studied RBP known as RBM38/RNPC1. The quantitative data from DO-RIP-seq out-performed current binding site methods at predicting other features of the binding sites of HuR and RBM38, for example the lack of RNA secondary structure, and preferences in binding to particular sub-motifs. My studies indicate that DO-RIP-seq will be useful in uncovering the determinants of RNA-protein interactions, and studying dynamic biological processes that could modulate these interactions.</p> / Dissertation
29

Rip current spacing in relation to wave energetics and directional spreading

Holt, Robert D. 06 1900 (has links)
Approved for public release, distribution is unlimited / Rip current spacings are compared with wave energetics and directional spreading in the Southern Monterey Bay. Southern Monterey Bay affords a unique environment to study rip currents owing to their prevalence created by near-normally incident waves on a sandy shoreline. It is hypothesized that rip current spacing is a function of wave directional spreading and energy flux, based on the morphodynamic modeling by Reniers et al. 2003. A gradient of wave energy flux exists due to headlands and refraction over Monterey Canyon. Rip currents are shown to occur between cusps in the shoreline, allowing cusp spacing to be a surrogate for rip spacing. Rip current spacing was inferred from beach morphology surveys, LIDAR imagery, and Argus cameras, and found to be O(150m) at Sand City and O(300m) at Marina, separated by 6km . Measured waves during a two month period using wave-rider buoys, show a gradient of across-shore energy flux between Sand City, 2 28000( / ) F Jm x . , and Marina, 2 33000( / ) F Jm x . . The two sites have the same peak directional spreading of energy value, 14 peak ̤= o , and slightly different bulk values for Sand City, 18 bulk ̤= o , and Marina, 20 bulk ̤= o . Therefore, the variations in rip current spacing could not be attributed to directional spreading but appear related to variations in energy flux. / Ensign, United States Naval Reserve
30

Caracterização filogenética das proteínas inativadoras de ribossomos (RIPs) de mamona (Ricinus communis L.) e análise da expressão dos genes Rcom RIPs durante o desenvolvimento da semente

Morais, Guilherme Loss de January 2010 (has links)
As Proteínas Inativadoras de Ribossomos (RIPs) compreendem uma família de enzimas que inibem a síntese protéica através da depurinação de uma adenina específica do RNA ribossomal. Os membros desta família são classificados como RIPs do tipo I, quando possuem somente o RNA-N-Glicosidase e RIPs do tipo II quando além do domínio glicosidase, também apresentam um domínio de lectina. As RIPs foram mais estudadas em plantas, onde a ricina e a aglutinina, ambas RIP do tipo II de mamona (Ricinus communis), estão entre as primeiras descritas. O presente trabalho teve o objetivo de identificar parálogos da ricina e aglutinina, bem como RIPs do tipo I de mamona e analisar as suas relações filogenéticas. Além disso, validar o uso de 14 potenciais genes de referência para qRT-PCR em cinco estádios do desenvolvimento da semente de mamona. O padrão de expressão gênica por RT-qPCR de todas RIPs de mamona identificadas, também foram analisados nestes mesmos estádios. Um total de 18 genes de RIPs foi identificado em mamona (Rcom RIPs), dos quais 10 foram classificados como do tipo II e 8 do tipo I. As topologias das árvores filogenéticas sugerem que as Rcom RIPs foram originadas a partir de múltiplos eventos de duplicação gênica. Dois modelos evolutivos foram propostos para a radiação das Rcom RIPs, baseados em processos de fusão gênica associado ou não a eventos de duplicação parcial. Os genes Act 2/7, EF β, Ubi, TIP e UBC foram os que apresentaram perfil de expressão mais estável e foram selecionados para subsequente normalização dos dados de expressão das Rcom RIPs. Os genes que codificam as Rcom RIPI 3, 4, 5, 7 e 8 e as Rcom RIPII 1, 2, 4, 5, 6 e 8 são transcritos em sementes, sendo que a Rcom RIPII 1 (ricina) e a Rcom RIPII 2 (aglutinina) foram as mais expressas. O presente trabalho apresenta um modelo evolutivo das Rcom RIPs, o qual pode ser extrapolado para outras espécies de plantas. Este trabalho também demonstra o primeiro esforço para a padronização de genes de referência para RT-qPCR em mamona e o primeiro que apresenta a expressão outras Rcom RIPs, além da ricina e aglutinina. / Ribosome inactivating proteins (RIPs) comprise a family of enzymes that inhibit protein synthesis, after depurination of an adenine-specific ribosomal RNA. The members of this family are classified as type I RIPs, which have a RNA-Nglycosidase domain and type II RIPs encompassing a RNA-N-glycosidase and a lectin domain.The RIPs were more studied in plants, where ricin and agglutinin, both type II RIP of castor bean (Ricinus communis), were the first to be described. This work aimed to: 1) identifine paralogous of ricin and agglutinin, as well as the type I RIPs of castor bean; 2) analyze their phylogenetic relationships; 3) validate the use of 14 potential housekeeping genes for qRT-PCR for five developmental stages of R. communis seeds; 4) analyze the pattern of gene expression by RTqPCR of all RIPs castor identified in these same stages. A total of 18 genes that encode RIPs were identified in castor bean (Rcom RIPs), 10 of which were classified as type II and 8 as type I. The phylogenetic trees topologies suggest that Rcom RIPs were originated from multiple events of gene duplications. Two evolutionary models have been proposed for the radiation of Rcom RIPs based on gene fusion processes associated or not to events of partial duplication. The genes Act 2/7, EF β, Ubi, TIP and UBC presented the more stable expression profile and were selected for further RT- qPCR normalization experiments. The Rcom RIPI 3, 4, 5, 7 and 8 and Rcom RIPI 1, 2, 4, 5, 6 and 8 genes are actively transcribed in seeds, whereas the Rcom RIPI 1 (ricin) and Rcom RIPI 2 (agglutinin) were the most expressed. This paper presents an evolutionary model of Rcom RIPs, which can be extrapolated to other plant species. Also, corresponds to the first effort to standardize housekeeping genes for RT-qPCR in castor bean and the first that shows the expression Rcom RIPs, other than ricin and agglutinin.

Page generated in 0.0286 seconds