• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 187
  • 34
  • 27
  • 25
  • 9
  • 8
  • 4
  • 2
  • 1
  • 1
  • Tagged with
  • 388
  • 87
  • 75
  • 68
  • 63
  • 55
  • 52
  • 49
  • 46
  • 45
  • 42
  • 39
  • 38
  • 35
  • 34
  • 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.
221

Alternative Splicing: Peeling Another Layer of Cold Stress Response in Tomato

Jasjit Singh Mangat (19825476) 10 October 2024 (has links)
<p dir="ltr">Tomato, being a tropical species, is sensitive to temperatures below 10°C, thus limiting its growth to warmer regions and greenhouses. Understanding the cold response pathways in tomato will help improve its climate resiliency through breeding and biotechnology. Reportedly, plant genes undergo alternative splicing (AS) in response to various environmental stresses, however, the scope and dynamics of alternative splicing events in response to cold are unknown in tomato. To fill this knowledge gap, a fine-scale time-series cold (4°C) experiment was performed followed by RNA-sequencing of shoot and root tissues in tomato. Computational analysis revealed that various AS events occur within the first 20 minutes of temperature reduction and later on. Many AS genes were common between shoots and roots, however, the majority of the changes were organ-specific. Circadian rhythm and photosynthesis were the most significant among the various impacted biological processes, highlighting their importance in cold stress response. This study will help us gain insights into cold response pathways of tomato and other commercially important, closely related Solanaceae species.</p>
222

<b>Investigation of odorant receptors associated with nestmate recognition in the Argentine ant, </b><b><i>L</i></b><b><i>inepithema humile</i></b>

Mathew A. Dittmann (5930612) 18 April 2024 (has links)
<p dir="ltr">Given the relatively poor visual acuity of compound eyes, many insects have developed alternative means for navigating their environment. For example, insects often rely on chemosensation to find food, mates, and inter- and intraspecific communication. Eusocial insects in particular have developed complex systems of pheromone communication to organize their colonies, enabling them to partition labor for foraging, brood care, and colony defense tasks to different portions of the colony. A variety of genes coding for proteins are involved in detecting these chemicals, including gustatory receptors, ionotropic receptors, and odorant receptors (ORs). Eusocial insects, and especially ants, have evolved an expanded clade of ORs in their genome, likely due to an increased reliance on pheromones compared to other insects. The ability to recognize nestmates from non-nestmates is one of the vital functions performed by these ORs, which detect hydrocarbons present on the cuticle to distinguish friend from foe. However, research into the details of nestmate recognition has been stymied due to difficulties in manipulating OR genes. Despite advances in genetic sequencing and manipulation technologies, strict reproductive divisions within most ant lineages make generating transgenic ants nearly impossible, and so we have been left with limited options to further investigate these receptors. To narrow down the ORs that could be involved in nestmate recognition in the Argentine ant (Mayr, 1868), I took a multi-pronged approach of generating tissue transcriptomes to identify ORs that are selectively upregulated in the antennae, as well as conducting a phylostratigraphic analysis to identify which OR genes arose more recently in the Argentine ant genome. While conducting these analyses, it became necessary to reannotate the set of Argentine ant OR genes, due to current published annotations not containing the full breadth of <i>L. humile</i> ORs. Finally, I orally administered fluorescently-labelled dsRNA to workers, and tracked the extent to which ingested dsRNA is capable of traversing the tissues of ant workers, to investigate whether RNAi is a viable method for investigating gene function for genes showing tissue-selective expression. I discovered a subset of OR genes that are highly expressed in the antennae and confirmed that dsRNA is able to reach the antennae and knock down OR gene expression through ingestion, meaning that RNA interference is a viable method for the practical study of ant OR genes and can be used to further explore how individual ORs regulate nestmate recognition.</p>
223

Comparative responses of salmon to sea lice Lepeophtheirus salmonis infections, and lice responses to chemical and environmental stressors

Sutherland, Ben James Gerard 29 May 2014 (has links)
Systems biology methods can provide novel insight into the responses of an organism to a suboptimal environment, an infection or exposure to a xenobiotic. In the interaction of salmon and salmon lice, there are several areas requiring further research. These include the impacts of lice infection on wild salmon, response mechanisms of different salmon species or life stages to lice infections, effects of environmental conditions on lice stress, and mechanisms underlying the emergence of resistance to important parasiticidal chemicals. Here, I combine global gene expression analyses with phenotypic and physiological responses of salmon or salmon lice to further our understanding of these topics. In the first chapter, I introduce the work by discussing relevant background material on the current knowledge of salmon and salmon lice interactions, salmon immunity, the state of salmon and louse genomics and the emerging field of ecological genomics. I also discuss how these approaches are applied to the study of non-model organisms and sustainable aquaculture development and fisheries conservation. In the second chapter, I present the first large-scale transcriptome profiling of a Pacific salmon to a salmon lice infection, identifying transcript signatures associated with an infection in a sensitive life stage of pink salmon Oncorhynchus gorbuscha. In the third chapter, I present the results of multiple co-habitation infections of three species of Pacific and Atlantic salmon to compare physiological and transcriptomic responses at the local (skin) and systemic levels (anterior kidney). In the fourth chapter, I explore louse transcriptome functioning during temperature and salinity perturbations to characterize the molecular stress response and coping strategies of lice, as well as provide stressor context to response genes. In the fifth chapter, I evaluate sensitive Pacific and resistant and sensitive Atlantic lice responses to emamectin benzoate, an important compound for louse control which has recently been evaded by the louse through resistance development in multiple regions worldwide. In the sixth and final chapter, I conclude with a synthesis of what was learned about knowledge gaps discussed above and how to best apply this information by providing some approaches for future research to address remaining challenges. / Graduate / 0369 / 0792 / 0718 / bensutherland7@gmail.com
224

Transcript profiling of small tissue samples using microarray technology

Sievertzon, Maria January 2005 (has links)
<p>Through a number of biological, technological and computational achievements during the 20th century and the devoted work of hundreds of researchers the sequence of the human and other genomes are now available in public databases. The current challenge is to begin to understand the information encoded by the DNA sequence, to elucidate the functions of the proteins and RNA molecules encoded by the genes as well as how they are regulated. For this purpose new technologies within the area of functional genomics are being developed. Among those are powerful tools for gene expression analysis, such as microarrays, providing means to investigate when and where certain genes are used.</p><p>This thesis describes a method that was developed to enable gene expression analysis, on the transcriptome level, in small tissue samples. It relies on PCR amplification of the 3’-ends of cDNA (denoted 3’-end signature tags). PCR is a powerful technology for amplification of nucleic acids, but has not been used much for transcript profiling since it is generally considered to introduce biases, distorting the original relative transcript levels. The described method addresses this issue by generating uniformly sized representatives of the transcripts/cDNAs prior to amplification. This is achieved through sonication which, unlike restriction enzymes, does not require a specific recognition sequence and fragments each transcript randomly. The method was evaluated using cDNA microarrays, Affymetrix™ oligonucleotide arrays and real-time quantitative PCR. It was shown to perform well, yielding transcript profiles that correlate well to the original, unamplified material, as well as being highly reproducible.</p><p>The developed method was applied to stem cell biology. The variability in gene expression between different populations of cultured neural stem cells (neurospheres) was investigated. It was shown that neurospheres isolated from different animals or passaged to different degrees show large fluctuations in gene expression, while neurospheres isolated and cultured under identical conditions are more similar and suitable for gene expression analysis. A second study showed that withdrawing epidermal growth factor (EGF) from the culture medium when treating the cells with an agent of interest has profound effects on gene expression, something which should be taken into consideration in future neurosphere studies.</p>
225

Déterminisme nutritionnel et génétique de la teneur en lipides musculaires chez la truite arc-en-ciel (Oncorhynchus mykiss) : étude par analyse de l'expression de gènes candidats, du protéome et du transcriptome du foie et du muscle

Kolditz, Catherine-Inès 09 December 2008 (has links)
Ce travail de thèse a eu pour objectif d’identifier les mécanismes majeurs intervenant dans la régulation de l’adiposité musculaire chez la truite arc-en-ciel. Pour cela, nous avons analysé les effets combinés de la sélection génétique et de l’alimentation, facteurs prépondérants de variation de l'adiposité. Deux lignées de truites arc-en-ciel sélectionnées sur la teneur en lipides du muscle dorsal ("muscle gras" et "muscle maigre"), ont été nourries pendant 6 mois avec un régime contenant 10 ou 23% de lipides (% de la matière sèche). Nous avons mesuré l'activité et/ou l'expression d’enzymes clé des principales voies métaboliques intervenant dans l'utilisation de l'énergie, puis développé une analyse différentielle globale à l’échelle du transcriptome (microarray nylon) et du protéome (électrophorèse bidimensionnelle). Ces analyses portent sur le muscle blanc, tissu cible de la sélection, et le foie, carrefour métabolique et site majeur de la lipogenèse chez les poissons. Les résultats obtenus confirment l’effet inhibiteur d’un apport alimentaire riche en lipides sur la lipogénèse et la désaturation des acides gras dans le foie, déjà observé chez des individus de plus grande taille, et fournissent de nouvelles connaissances sur l’effet exercé sur les autres voies, en particulier la protéolyse. Ces analyses ont également permis de mettre en évidence des différences métaboliques existant entre lignées, qui concernent non seulement le métabolisme des lipides mais aussi celui des autres substrats énergétiques. Il apparaît que les deux moyens utilisé pour augmenter la teneur en lipides du muscle mettent en jeu des mécanismes moléculaires différents. Nos travaux ont permis d’identifier deux gènes dont l’expression est augmentée dans le muscle en réponse à un apport alimentaire riche en lipides et par la sélection génétique en faveur d’un indice d’adiposité musculaire élevé, et qui pourraient être des marqueurs moléculaires de l’adiposité musculaire. / The objective of the study was to identify genes and proteins that are involved in the control of muscle fat deposition in rainbow trout. We analyzed the combined effects exerted by genetic selection and dietary treatment, which are the two main factors that can be used to manage body fat content. Two lines of rainbow trout, obtained after 3 generations of divergent selection for high or low muscle fat content, were fed diets containing either 10% or 23% lipids (% dry matter), for six months. We analyzed the activity and gene expression of key enzymes involved in energy utilization, and performed a more global approach through transcriptome (nylon microarray) and proteome (two- dimensional electrophoresis) analysis. We analyzed the liver, which is the centre of intermediary metabolism and the main site of lipogenesis in fish, and the muscle, the target tissue of the selection provedure. The results confirmed the depressing effect exerted by a lipid rich diet on lipogenesis and fatty acid desaturation, already described in larger size fish, and provided new insight about the effect exerted on the other metabolic pathways, in particular the proteolysis. These analyses pointed out metabolic differences existing between lines. They involved not only lipid metabolism, but also the other pathways of nutrient utilization. With regard to their muscle-fattening effect, the dietary treatment and the genetic selection appear to act through different molecular mechanisms. These analyses allowed the identification of two genes that are over-expressed in muscle upon both high dietary lipid supply and upward selection for muscle fat content, suggesting that these two genes could be relevant molecular markers of muscle fattening.
226

Regeneration and calcification in the Spirobranchus lamarcki operculum : development and comparative genetics of a novel appendage

Szabó, Réka January 2015 (has links)
Regeneration, the replacement of lost or damaged body parts, and biomineralisation, the biologically controlled formation of minerals, are important and widespread abilities in the animal kingdom. Both phenomena have a complex evolutionary history; thus their study benefits from investigations in diverse animals. Spirobranchus (formerly Pomatoceros) lamarcki is a small tube-dwelling polychaete worm of the serpulid family. Serpulids have evolved a novel head appendage, the operculum, which functions as a defensive tube plug and regenerates readily when lost. In S. lamarcki, the end of the operculum is reinforced by a calcareous plate; thus, the operculum is a good system in which to study both regeneration and biomineralisation. This thesis explores several aspects of these important processes in the adult operculum. First, a time course of normal regeneration is established. Next, cell proliferation patterns are described, suggesting a combination of proliferation-dependent and proliferation-independent elements in opercular regeneration. The formation of the calcareous opercular plate is examined using both microscopic observations of whole opercular plates and X-ray diffraction analysis of isolated plate mineral, revealing a large shift in mineralogy over the course of regeneration. Histochemical study of alkaline phosphatase enzyme activity indicates the importance of these enzymes in the operculum, although their precise functions are as yet unclear. Finally, a preliminary survey of three opercular transcriptomic datasets is presented, with a broad sampling of gene families with regeneration- or biomineralisation-related roles in other animals. The opercular transcriptome constitutes the first biomineralisation transcriptome from any annelid, and one of the first transcriptomic datasets related to annelid regeneration. Many of the candidate genes examined here display interesting behaviour and suggest targets for further investigation. The work presented here establishes the S. lamarcki operculum as a promising model system in the field of evolutionary developmental biology.
227

Desenvolvimento de uma ferramenta computacional para análise de co-expressão gênica e sua aplicação na biologia de sistemas / Development of a computational tool for gene co-expression analyses and its application in systems biology

Russo, Pedro de Sa Tavares 09 May 2019 (has links)
A Biologia de Sistemas proporciona um olhar holístico sobre os processos biológicos, integrando os diversos componentes intracelulares através de redes altamente complexas. Em particular, redes de co-expressão tem permitido nos últimos anos uma compreensão cada vez maior dos sistemas biológicos e dos mecanismos moleculares que os regem. Por outro lado, as ferramentas matemáticas e estatísticas já desenvolvidas para a análise destas redes e sistemas são, em geral, densas e pouco familiares para profissionais das áreas biológicas e da saúde. Portanto, a fim de possibilitar uma análise ao mesmo tempo relevante e facilitada, nosso grupo criou a ferramenta CEMiTool, que tem por objetivo identificar módulos de coexpressão de genes de modo automático, de maneira fácil e intuitiva para usuários com pouca ou nenhuma experiência com linguagens de programação. A fim de demonstrar a facilidade de uso da ferramenta, aplicamos o CEMiTool a mais de 1000 estudos de transcriptômica, cujos resultados foram utilizados para a confecção de um banco de dados, permitindo a integração de informações entre estudos. Além disso, para facilitar ainda mais o acesso a este tipo de análises, foi criada uma versão online da ferramenta, denominada webCEMiTool, que permite realizar as análises no navegador. Finalmente, criou-se também a ferramenta annotator, permitindo a definição automática de grupos de amostras de estudos de transcriptômica a partir do agrupamento de cadeias de caracteres presentes em dados de anotação. Todo o código está livremente disponível à comunidade. / System biology methods provide a holistic view of biological processes, integrating the several intracellular molecular components via the use of highly complex networks. In particular, co-expression networks have allowed for an increasing understanding of biological systems and the complex molecular mechanisms driving them. On the other hand, previously described tools for the analysis of biological networks are in general relatively difficult to use for life and health scientists given their high mathematical and computational demand. Therefore, in order to provide at the same time a relevant and easy-to-use analysis, we have developed the CEMiTool package, which aims to identify gene coexpression modules in an automatic, easy and intuitive way for users with little to no prior computational expertise. We applied CEMiTool to over 1000 transcriptomics studies and used the results to create a new gene coexpression database, which allows users to integrate information across analyses. Moreover, to further facilitate analyses we developed an online version of the tool named webCEMiTool, which permits users to run coexpression analysis easily via browser. Finally, we also developed annotator, a package for automatically determining experimental groups based on sample annotation string similarity. All code is freely available to the community.
228

Novel approach for identification of biocatalysts by reverse omics techniques

Egelkamp, Richard 20 February 2019 (has links)
No description available.
229

Développement d'hydrolysats destinés à la formulation d'aliments pour l'aquaculture : normalisation structurale et optimisation fonctionnelle / By-product hydrolysates for aquafeed : structural standardization and functional optimization

Leduc, Alexandre 16 October 2018 (has links)
L'aquaculture est en pleine expansion et fournit aujourd'hui la moitié des produits aquatiques destinés à la consommationhumaine. Elle constitue ainsi un secteur clé pour le maintien et l'amélioration de la sécurité alimentaire dans lemonde. Le développement de l'aquaculture est étroitement lié à celui des formules alimentaires. Ces dernières années,la part des farines de poisson dans la formulation des aliments a particulièrement diminué au profit des farines d'originevégétale pour répondre aux nombreuses contraintes économiques et environnementales. Néanmoins, ces matièrespremières sont moins adaptées aux besoins nutritionnels des poissons carnivores et leur utilisation peut entraîner unebaisse des performances de croissance et d'efficacité alimentaire. L'ajout d'additifs et d'ingrédients fonctionnels devientalors indispensable. Les hydrolysats protéiques issus des co-produits de la pêche et de l'aquaculture sont des ingrédientsà fort potentiel appétence, nutritionnel et bioactif. Ces ingrédients sont des mélanges complexes riches en peptides hydrolytiqueset en acides aminés libres, mais dont la composition varie en fonction de l'origine de la matière première etdes paramètres d'hydrolyse appliqués lors de leur fabrication. Au cours de ces travaux de thèse, nous avons développéet mis en pratique des outils permettant d'approfondir la caractérisation structurale et les propriétés fonctionnellesdes hydrolysats de protéines. Dans un premier temps, nous avons développé une méthode analytique basée sur unenormalisation des échantillons suivie d'une détermination de l'abondance et de la richesse en peptides par chromatographied'exclusion stérique et chromatographie liquide couplée à la spectrométrie de masse de type électro-spray,respectivement. Les résultats présentés sous forme d'un diagramme 2D permettant de classer et comparer facilementles hydrolysats de protéines de forme galénique, d'origine et de process différents. Nous avons également développé unoutil in vitro sur l'intestin de bar européen, Dicentrarchus labrax, permettant de déterminer les activités myotropesdes hydrolysats. Nous avons pu notamment démontrer que l'hydrolysat de crevettes possède une plus forte activitémyotrope que les hydrolysats de poissons et que cette activité est portée par un pentapeptide KNPEQ clivé à partirde l'hémocyanine lors du process d'hydrolyse appliqué sur les co-produits de crevette. Enfin, dans un second temps,un conditionnement alimentaire de 65 jours a été conduit chez le bar européen nourri avec un aliment pauvre en farinede poisson supplémenté en hydrolysat de différentes origines et couplé à une analyse d'expression génique (approcheen RNA-Seq Illumina). Cette étude a permis de montrer que les hydrolysats de protéines appliqués sur un alimentfaible en farine de poisson (5%) sont capables de restaurer des performances de croissance équivalentes à celles d'unrégime contenant 20% de farine de poisson mais qu'ils portent par ailleurs des propriétés fonctionnelles spécifiques.Il a également été montré que le mélange des deux hydrolysats permet de moduler les transcriptomes intestinal ethépatique de façon plus profonde que lorsque que les hydrolysats sont utilisés séparément. Ces résultats confirmentl'intérêt des hydrolysats de protéines pour la formulation d'aliment à faible teneur en farines de poisson et apportentde nouveaux outils de caractérisation de ces ingrédients complexes, qui seront utiles pour leur optimisation et leurstandardisation ainsi que pour la compréhension de leurs mécanismes d'action chez les poissons. / Aquaculture is a key sector for supporting and improving the food security worldwide. The global production of farmedfish and shrimp has grown dramatically over the past decades and now contributes to half of the aquatic productsintended for human consumption. Aquaculture will require feeds to support its growth but availability of some raw materialssuch as fish meal are limited. The use of fish meal in aquafeed has particularly declined in favor of plant proteinsources to fit with economic and environmental constraints. But plant proteins do not meet perfectly the nutritionalrequirements of carnivorous fish and their utilization often results in lower growth and feed performances. Proteinhydrolysates manufactured from fishing and aquaculture co-products are ingredients with a high palatable, nutritionaland bioactive potential. They are rich in hydrolytic peptides and free amino acids, but they are complex mixtureswhose composition could vary according to raw material origin and hydrolysis parameters. During this PhD study, wedeveloped and implemented tools to further characterize the structure and functional properties hydrolysates. On afirst step, we developed a fast methodological tool based on sample standardization, followed by the determination ofthe abundance and richness of peptides using size exclusion chromatography and liquid chromatography coupled toelectro-spray mass spectrometry, respectively. We merged the results into a 2D diagram that made it easy to classifyand compare hydrolysates having different galenic, origin and process. We also developed a tool on isolated intestinefrom European seabass (Dicentrarchus labrax ) to rank protein hydrolysates according to their myotropic property.We demonstrated that shrimp hydrolysate showed a higher myotropic activity than fish hydrolysates and that thisactivity was carried by a unique pentapeptide KNPEQ produced by the enzymatic clivage of haemocyanin during thehydrolysis process applied on shrimp co-products. On a second step, a 65-day feeding trial was conducted in Europeanseabass fed a low fish meal diet supplemented with protein hydrolysates of different origin, and coupled to a studyof the intestine and liver transcriptomic response (Illumina RNA sequencing). It has been shown that protein hydrolysatesincluded in a low fish meal diet (5%) restored growth performances to the same level than a diet containing20% of fishmeal, and that they exhibited very specific functional properties. These results showed that a mixture oftwo hydrolysates impacted more deeply the intestine and liver transcriptomes than hydrolysate tested alone. ThisphD study confirmed that protein hydrolysates are very interesting candidates for formulating low fish meal feed andoffer new tools for characterizing such complex ingredients, which will be useful to optimize and standardize proteinhydrolysate while understanding their mechanisms of action in fish.
230

Proteômica e transcriptômica aplicadas ao estudo da variabilidade do veneno de Bothrops jararaca (serpentes:viperidae) / Proteomics and transcriptomics applied to the study of Bothrops jararaca venom variability (Serpentes: Viperidae)

Pereira, André Zelanis Palitot 30 May 2011 (has links)
Estudos prévios demonstraram que as atividades biológicas do veneno da serpente Bothrops jararaca sofrem significantes modificações ontogenéticas. Neste estudo é apresentada uma análise comparativa do proteoma, peptidoma e transcriptoma da glândula de veneno de filhotes e adultos de B. jararaca, correlacionando os resultados obtidos com algumas características funcionais dos venenos. Venenos de 694 filhotes de até duas semanas de idade e 110 adultos, provenientes do Estado de São Paulo foram extraídos e liofilizados para as análises proteômicas/peptidômicas e funcionais. O mRNA de glândulas de veneno de 20 filhotes e 10 adultos foi obtido para a contrução de bibliotecas de cDNA e a análise de Expressed Sequence Tag (ESTs). Demonstramos que a atividade hemorrágica é similar para os venenos de filhotes e adultos, enquanto que o veneno de adultos é discretamente mais letal para camundongos; entretanto, o veneno de filhotes mostrou-se extremamente mais letal para aves, uma característica que pode garantir proteção contra potenciais predadores nas fases iniciais de vida da espécie. A atividade coagulante do veneno de filhotes é cerca de 10 vezes mais alta que aquela verificada para o veneno de adultos e é atribuída sobretudo à atividade de metaloproteinases. Essas diferenças nas atividades funcionais se refletiram nos diferentes perfis verificados por eletroforese bidimensional e identificação de spots de proteínas por digestão tripsínica in-gel seguida de análise por cromatografia líquida acoplada à espectrometria de massas em tandem, zimografia com gelatina, imunocoloração utilizando anticorpos específicos anti-proteinases, e glicoproteínas com afinidade pela concanavalina -A. A comparação dos venenos por derivatização com tags isóbaros (iTRAQ) e a análise das ESTs revelaram diferenças claras entre os níveis de toxinas presentes nos venenos e as metaloproteinases foram a classe de toxinas mais expressa, além de serem as toxinas cujos perfis estruturais apresentaram maior mudança, como ilustrado pelo quociente PIII/PI, que é maior nos venenos de filhotes. Dimorfismo sexual foi detectado em diversas classes de toxinas no veneno de adultos por análises proteômicas e transcriptômicas e, surpreendentemente, o fator de crescimento de nervo foi detectado apenas no veneno/glândula de veneno de machos. A análise glicoproteômica mostrou que N-glicosilações parecem ser as modificações pós-traducionais mais proeminentes nas toxinas de B. jararaca, e os perfis de N-glicosilação apresentaram-se distintos para as proteínas dos venenos de filhotes e adultos. Entretanto, a composição de N-glicanos não variou entre as amostras, indicando que diferenças na utilização de motivos de N-glicosilação poderiam explicar as diferenças nos níveis de glicosilação observados pelos diferentes perfis eletroforéticos dos venenos. A análise da fração peptídica dos venenos de filhotes e adultos por espectrometria de massas resultou num perfil similar de Peptídeos Potenciadores de Bradicinina (BPPs), que foram detectados em suas formas canônicas e também com novas seqüências, cujas estruturas primárias sugerem um processamento da proteína precursora em sítios até então não descritos. Acreditamos que este seja o estudo mais abrangente sobre a variabilidade do veneno de uma serpente já realizado e os resultados demonstram que há uma relação clara entre as alterações ontogenéticas na dieta e tamanho corporal e o proteoma/peptidoma do veneno desta espécie. / Previous studies have demonstrated that the biological activities displayed by the venom of the snake Bothrops jararaca undergo a significant ontogenetic shift. In this investigation, we performed comparative proteomic, peptidomic and transcriptomic analyses of venoms and venom glands from newborn and adult specimens of B. jararaca and correlated the results with the evaluation of functional venom features. Venoms from 694 two-week old newborns and 110 adults from São Paulo state were milked and lyophilized for functional and proteomic/peptidomic analyses. Additionally, mRNA was obtained from the venom glands of 20 newborns and 10 adults and used for the construction of cDNA libraries and Expressed Sequence Tag (ESTs). We demonstrate that newborn and adult venoms have similar hemorrhagic activities, while the adult venom has a slightly higher lethal activity upon mice; however, the newborn venom is extremely more potent to kill chicks, a feature that might ensure protection against potential predators in early stages of B. jararaca life. Interestingly, the coagulant activity of the newborn venom upon human plasma is ten times higher than that of the adult venom and is contributed mainly by metalloproteinases. Differences in functional activities were clearly reflected in the venom different profiles of two-dimensional gel electrophoresis (2D-PAGE) and protein spot identification by in-gel trypsin digestion followed by liquid chromatography and tandem mass spectrometry (LC-MS/MS), gelatin zimography, immunostaining using specific anti-proteinase antibodies, and concanavalin A-binding proteins. The venom comparison by isobaric tag peptide labeling (iTRAQ) and ESTs analysis revealed clear differences in toxin levels. The metalloproteinases were detected as the toxin class most expressed in the venoms in addition to being the toxins whose structural profile most changed, as illustrated by the ratio P-III/P-I class being higher in newborn venoms. Sexual dimorphism has been detected in various adult venom toxin classes by proteomic and transcriptomic analyses and, interestingly, the nerve growth factor was detected only in the male venom gland/venom. The glycoproteomic analysis showed that N-glycosylation seems to be the most prominent post-translational modification in B. jararaca toxins and the N-glycosylation profiles differed for newborn and adult venom toxins. Nevertheless, the N-glycan composition between the samples did not vary indicating that differences in the utilization of the N-glycosylation motif could be the explanation for the differences in the glycosylation levels indicated by the differential electrophoretic profiles of venom proteins. The analysis of the peptide fraction of newborn and adult venoms by mass spectrometry revealed a similar profile of Bradykinin Potentiating peptides (BPPs), however these were detected in the venoms showing their canonical sequences and also novel sequences corresponding to BPPs processed from their precursor protein at sites so far not described. To the best of our knowledge, this is the most comprehensive study on a snake venom variation and the results clearly demonstrate a relationship between the ontogenetic shift in diet and animal size, and the venom proteome/peptidome in B. jararaca species

Page generated in 0.0727 seconds