• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 79
  • 31
  • 17
  • 9
  • 8
  • 8
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 190
  • 35
  • 20
  • 14
  • 13
  • 13
  • 13
  • 13
  • 13
  • 12
  • 12
  • 11
  • 10
  • 10
  • 10
  • 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.
141

Efectos de la poliaminas y los fructooligosacáridos de la dieta sobre la maduración intestinal en cerdos destetados precozmente

Sabater Molina, María 03 November 2008 (has links)
Se evaluaron los efectos de formulas infantiles suplementadas con poliaminas y con fructooligosacaridos a dosis fisiológicas, sobre la maduración intestinal en lechones destetados precozmente. Se alimentaron 40 cerdos neonatales con leche materna, fórmula control, fórmula suplementada con poliaminas (5 nmol/ml espermina y 20 nmol/ml espermidina) y fórmula suplementada con FOS (8 g/l) (n=10/grupo experimental) durante un periodo de 13 días (del día 2 al 15 postparto). Nuestros resultados mostraron un aumento significativo en la profundidad de las criptas a nivel de yeyuno en el grupo de animales alimentado con poliaminas. El efecto bifidogénico de los FOS se asoció con una mayor concentración de poliaminas en el contenido cecal de cerdos neonatales y con una disminución de los parámetros de maduración intestinal analizados. Las cepas seleccionadas por el consumo de FOS, Bifidobacterium spp, Lactobacillus fermentum y Lactobacillus acidophilus fueron capaces de producir poliaminas in vitro. El estudio in vitro, no mostró una relación dosis-dependiente entre la concentración de FOS y la producción de poliaminas bacterianas. / It was evaluated the effects of infant formula supplemented with polyamines and fructooligosaccharides at physiological doses on gut maturation in newborn piglets. Forty newborn piglets were fed maternal milk, a control formula, a formula supplemented with polyamines (5 nmol / ml and 20 nmol spermine / spermidine ml) or a formula supplemented with FOS (8 g/l) (n = 10/experimental group) for 13 days (day 2 after birth through day 15). Animals fed polyamines showed a significant increase in crypt depth of jejunum. The bifidogenic activity of FOS was associated with an increased polyamine concentration in the cecal content of piglets and a decrease in gut maturation parameters analyzed. The Bifidobacterium spp., L. fermentum and L. acidophilus, the most predominant strains after FOS supplementation, were able to produce polyamines in vitro. However, there was not a dose-dependent relationship between FOS addition to the bacterial cecal content and polyamine production in vitro.
142

Výskyt biogenních aminů a polyaminů ve zrajících sýrech po ukončení doby spotřeby / Content of biogenic amines and polyamines in expired ripening cheeses

VODEHNALOVÁ, Klára January 2012 (has links)
The aim of this thesis was to observe the occurrence of biogenic amines and polyamines in selected types of ripening cheeses and to assess the content of the materials since the expiration date. Content of biogenic amines and polyamines in chosen samples was monitored last day of the expiration date, a week after the expiration date, two weeks after the expiration date, and after four weeks from the end of the expiration date.
143

Sledování obsahu biogenních aminů a polyaminů při skladování a kuchyňských úpravách jedlých hub. / Changes of biogenic amines and polyamines content during storage and heat treatments of edible mushrooms.

PEKÁRKOVÁ, Jana January 2013 (has links)
The target of this thesis was found content of eight biogenic amines and polyamines, specifically putrescine (PUT), spermidine (SPD), spermine (SPM), histamine (HIM), cadaverine (CAD), 2-phenylethylamine (PEA), tyramine (TYM) and tryptamine (TRM) in growed Agaricus hortensis during storage, frozen and heat treatment. There are many information dealing with these amines in the food in this time, but unfortunately data on the content of amines in edible mashrooms in literature are still missing. The samples were providing from company České houby a.s. in Soběslav. Those mushrooms were immediately processed. Frozen samples in PE sack (plastic bags) were tracked during three months. Boiled, blanched and raw samples of mushrooms were analysed in the beginning of concentration at day 0 and then 1, 2 and 4 days at 6 °C in the storage. Some samples of each experiment monitored after one day of storage at 22°C. Absolutely the highest concentrations found in all experiments with SPD. Changes in the content of amine modified and raw mushrooms during 4 days of storage at 6 ° C flow in both directions. The most important changes are visible immediately after blanching - a significant increase in TYM and even more pronounced in SPM. The increase was also showed in the content of the cooked mushrooms, in the SPD and to a higher volume in SPM. Storage at 22 ° C was mostly affected content PEA - the cooked mushrooms content significantly decreased, but blanched mushrooms increased. Also in raw mushrooms lead storage at this temperature for a significant increase in the SPM. Freezing substantially affect any of the amines. TRM and CAD analysis were not detected; HIM at lower limit was detected after cooking mushrooms and after storage of raw mushrooms at 22 ° C. I hope that the observed data can help extend the data in the literature and offers the opportunity to further focus of research in the field of biogenic amines in edible mushrooms.
144

TRAXOPRODIL ATENUA AS CONVULSÕES INDUZIDAS POR PENTILENOTETRAZOL / TRAXOPRODIL ATTENUATES PENTYLENETETRAZOL-INDUCED SEIZURES

Martignoni, Felipe Villa 23 September 2010 (has links)
There is evidence that while polyamines facilitate seizures by positively modulating N-methyl-D-aspartate receptors (NMDAr), selective antagonists of the NR2B-subunit decrease seizures. However, it remains undetermined whether traxoprodil (CP-101,606), an ifenprodil analog that acts as a selective antagonist of the NR2B subunit of the NMDAr, decreases seizure activity. In the current study we investigated whether traxoprodil alters PTZ-induced seizures in adult male Wistar rats by behavioral and electroencephalographical methods. Spermidine (SPD) (2 nmol/site; i.c.v.) facilitated behavioral and electroencephalographical seizures induced by a normally subeffective dose of PTZ (35 mg/kg; i.p.), but did not alter seizure activity induced by convulsant dose of PTZ (70 mg/kg; i.p). Traxoprodil (20 nmol i.c.v.) increased the latency to generalized tonic clonic seizures induced by PTZ (70 mg/kg; i.p). The oral administration of traxoprodil (60 mg/kg) increased the latency to clonic and tonic-clonic seizures, and decreased total time spent in seizures. These data constitute pharmacological evidence supporting a role for NR2B subunit in PTZ-induced seizures. While more studies are necessary to determine whether traxoprodil is a useful anticonvulsant in clinical settings, NR2B subunits may represent new targets of drug development for convulsive disorders. / Há evidências de que as poliaminas facilitam convulsões por modular positivamente os receptores N-metil-D-aspartato (NMDAr), e que os antagonistas seletivos a subunidade NR2B do NMDAr têm atividade anticonvulsivante. Entretanto, permanece indeterminado se o traxoprodil (CP-101,606), um análogo do ifenprodil que age como antagonista seletivo na subunidade NR2B do NMDAr, tem efeito anticonvulsivante. Neste estudo investigamos se o traxoprodil altera as convulsões induzidas por pentilenotetrazol (PTZ) em ratos Wistar machos por meio de métodos comportamentais e eletroencéfalográficos (EEG). Espermidina (SPD) (2 nmol/sítio; i.c.v.) facilita as convulsões comportamentais e eletroencéfalográficas induzidas por doses subconvulsivantes de PTZ (35 mg/kg; i.p.), mas não altera a atividade convulsiva induzida por dose plenamente convulsivante de PTZ (70 mg/kg; i.p.). Traxoprodil (20 nmol i.c.v.) aumenta a latência para convulsão tônico-clônica generalizada induzida por PTZ (70 mg/kg; i.p.). A administração oral de traxoprodil (60 mg/kg) aumenta as latências para convulsão clônica e tônico-clônica generalizada e diminui a duração total das convulsões induzidas por PTZ (70 mg/kg; i.p.). Esses dados mostram que o traxoprodil diminui as convulsões induzidas por PTZ, um modelo animal com bom poder de predição de atividade convulsivante em humanos, e sugerem um papel para a subunidade NR2B nas convulsões induzidas por PTZ. Enquanto mais estudos são necessários para determinar se o traxoprodil tem, de fato, atividade anticonvulsivante na clínica, as subunidades NR2B podem representar um novo alvo para o desenvolvimento de drogas anticonvulsivantes.
145

ENVOLVIMENTO DO SISTEMA OPIÓIDE NA DEPENDÊNCIA DE ESTADO INDUZIDA PELA ARCAÍNA EM RATOS / Arcaine-induced state-dependent memory involves opioid mechanisms in rats

Mariani, Raquele Kipper 02 March 2011 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Arcaine is a competitive antagonist of the polyamine binding site at the NMDA receptor which induces state-dependent recall. However, no study has addressed the involvement of other neurotransmitter/neuromodulators in arcaine-induced state dependency. The current study investigates whether the opioid system is involved in arcaine-induced state-dependent memory retrieval of the inhibitory avoidance task (IA) in rats. The systemic administration of arcaine (30 mg/kg, i.p.) or morphine (5 mg/kg, i.p.) zero, 3, 6 or 9 hours posttraining, reduced step-down latencies at testing. Arcaine (30 mg/kg, i.p.) or morphine (5 mg/kg, i.p.) injection 30 min before testing reversed the performance deficit induced by administration of arcaine or morphine zero, 3 or 6, but not 9 hours post-training. The reversal of arcaine-induced impairment of IA performance was completely transferred to morphine, and vice-versa. The association of low and ineffective doses of morphine and arcaine (10 and 1.5 mg/kg, respectively) were additive and caused state-dependency. Naloxone (2 mg/kg, 3 min post-training, or 1 mg/kg, 1 hour pre-test, i.p.), reversed the amnesia and the state dependency induced by morphine and arcaine. These results suggest that state dependency induced by arcaine involves the opioid system. / A arcaína é um antagonista do sítio de ligação das poliaminas no receptor NMDA, a qual induz dependência de estado. No entanto, nenhum estudo abordou o envolvimento de outros neurotransmissores/neuromoduladores na dependência de estado induzida pela arcaína. No presente estudo, investigamos se o sistema opióide está envolvido na dependência de estado induzida pela arcaína na tarefa de esquiva inibitória (IA) em ratos. A administração sistêmica de arcaína (30 mg/kg, i.p) ou morfina (5 mg/kg, i.p) zero, 3, 6 ou 9 horas pós-treino, reduziu a latência de descida da plataforma no dia do teste. A injeção de arcaína (30 mg/kg, i.p) ou morfina (5 mg/kg, i.p) 30 minutos antes do teste, reverteu o déficit de desempenho induzido pela administração de arcaína ou morfina zero, 3 ou 6, mas não 9 horas pós-treino. A reversão da piora da memória induzida pela arcaína foi totalmente transferida para a morfina, e vice-versa. A associação de baixas doses de arcaína e morfina (10 e 1,5 mg/kg, respectivamente), que individualmente não pioraram a memória, induziram dependência de estado. A naloxona (2 mg/kg, 3 min pós-treino, ou 1 mg/kg uma hora pré-teste, i.p), reverteu a amnésia e a dependência de estado induzida pela arcaína e morfina. Esses resultados sugerem que a dependência de estado induzida pela arcaína envolve o sistema opióide.
146

Fitorreguladores no cultivo in vitro da gabirobeira (Campomanesia spp.) e baruzeiro (Dipteryx alata Vog.) / Phytorregulators in the in vitro culture of gabirobeira (Campomanesia spp.) and baruzeiro (Dipteryx alata Vog.)

Pinhal, Hernane Fernandes 29 June 2017 (has links)
FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais / A gabirobeira (Campomanesia spp.) e o baruzeiro (Dipteryx alata Vog) são duas fruteiras nativas do Cerrado com grande potencial devido ao seu aproveitamento alimentar e suas múltiplas possibilidades de utilização. A cultura de tecidos pode colaborar tanto para o cultivo quanto para a preservação destas espécies. Assim, neste trabalho, foram realizados experimentos com diversos fitorreguladores no cultivo in vitro das duas fruteiras. No experimento feito com a gabirobeira, foram testadas três poliaminas (espermina, espermidina e putrescina) em duas concentrações (0,5 e 1,0 mg L-1) para a multiplicação in vitro da gabirobeira utilizando, como explantes, segmentos nodais de plantas estabelecidas in vitro. Os resultados mostraram que as poliaminas não foram eficientes no desenvolvimento dos explantes de gabirobeira. Porém, o subcultivos de segmentos nodais pode funcionar como método de multiplicação in vitro da gabirobeira. Já nos estudos relacionados ao baruzeiro, foram realizados trabalhos comparando a ação de sete fitorreguladores (espermina, espermidina, putrescina, 2iP, cinetina, zeatina e BAP) e também a combinação de doses de BAP e ANA na multiplicação in vitro do baruzeiro, utilizando dois tipos de explantes: sementes e segmentos nodais de plantas estabelecidas in vitro. Para as sementes, a zeatina foi o fitorregulador que proporcionou a formação do maior número de brotações, enquanto a variação das doses de BAP e o uso de ANA não foram efetivos para a multiplicação in vitro. Quando os explantes utilizados foram segmentos nodais, a espermina foi o fitorregulador que, isoladamente, favoreceu a maior taxa de brotações por explante, enquanto a combinação de 0,5 mg L-1 de ANA e 12 mg L-1 de BAP mostrou-se a mais promissora para gerar brotações em segmentos nodais de baruzeiro. Assim, os dados aqui apresentados são importantes para a multiplicação in vitro da gabirobeira e do baruzeiro e podem subsidiar estudos futuros a relacionados ao tema. / The gabirobeira (Campomanesia spp.) and the baruzeiro (Dipteryx alata Vog.) are fruit trees native to the Brazilian Cerrado, both present great potential due to the value of their fruits as food and their multiple possibilities of usage. Tissue cultures can collaborate not only on cultivation, but also on the preservation of these species. Thereby, experiments with different growth regulators on in vitro cultivation of both fruit trees were performed in this work. In the experiment performed on the gabirobeira, three polyamines (spermine, spermidine and putrescine) in two concentrations (0.5 and 1.0 mg L-1) – designated to in vitro multiplication of the gabirobeira – were tested using nodal segments from plants established in vitro as explants. The results showed that polyamines were not efficient for the development of the gabirobeira explants. However, nodal segment subculturing can work as a method for in vitro multiplication of the gabirobeira. Furthermore, in the studies related to the baruzeiro, experiments were performed comparing the action of seven growth regulators (spermine, spermidine, putrescine, 2iP, kinetin, zeatin and BAP) and the combination of doses of BAP and NAA on in vitro multiplication of the baruzeiro, in which two types of explants were used: seeds and nodal segments from plants established in vitro. For seeds, zeatin was the growth regulator that provided the generation of the greatest number of shoots, whereas the variation of BAP doses and the use of NAA were not effective for in vitro multiplication. When nodal segments were used as explants, spermine was the growth regulator to single-handedly provide the highest rate of shoot formation per explant, whereas the combination of 0.5 mg L-1 of NAA and 12 mg L-1 of BAP revealed itself to be the most promising for the shoot induction in nodal segments from the baruzeiro. Therefore, the mentioned data are important to in vitro multiplication of the gabirobeira and the baruzeiro, and it can also support future research concerning the subject. / Tese (Doutorado)
147

Administração sistêmica de espermidina e arcaína altera a memória da tarefa de esquiva inibitória em ratos: envolvimento da dependência de estado / Systemic administration of spermidine and arcaine alters memory of the inibitory avoidance task in rats: state dependence involviment

Ceretta, Ana Paula Chiapinotto 06 December 2006 (has links)
The polyamines, putrescine, spermidine and spermine, are present in high concentrations in the central nervous system and, because of their policationic nature, they can interact with diverse cellular anionic targets (nucleic acids and proteins) and modulate the learning and memory by interacting with the polyamine binding site at N-methyl-D-aspartate receptor. In this study we investigated the effects of the systemic administration of spermidine and arcaine on the memory of the inhibitory avoidance task in rats. It was also determined whether the effects of the spermidine and arcaine involve state dependence. The animals were trained in an inhibitory avoidance apparatus (0.4 mA, 3s) and tested in the same apparatus 24 hours later. Immediate post-training administration of spermidine (50 mg/kg, i.p.) improved, while arcaine (10 and 30 mg/kg, i.p.) impaired step-down latencies in the inhibitory avoidance test. Administration of spermidine (50 mg/kg, i.p.) 15 minutes before testing did not alter the performance of rats which were injected with spermidine (50 mg/kg, i.p.) or vehicle immediately after training. However, administration of arcaine (30 mg/kg, i.p.) 15 minutes before testing reverted the impairment of memory caused by the administration of arcaine (30 mg/kg, i.p.) immediately after training. Administration of arcaine (30 mg/kg, i.p.) or MK-801 (0.03 mg/kg, i.p.) before testing partially reverted the impairment of memory caused by the administration of arcaine (30 mg/kg, i.p.) or MK-801 (0.03 mg/kg, i.p.) immediately after training, characterizing a crossed state dependence. The results suggest that memory improvement caused by the administration of spermidine immediately after training is not due to state dependence. In contrast, the impairment of memory induced by arcaine is due to state dependence. The crossed state dependence between arcaine and MK-801 supports that state dependence induced by arcaine is related to NMDA receptor hypofunction. / As poliaminas, putrescina, espermidina e espermina estão presentes em altas concentrações no sistema nervoso central e, por sua natureza policatiônica, podem interagir com sítios aniônicos de macromoléculas (ácidos nucléicos e proteínas) e modulam o aprendizado e a memória interagindo com o sítio de ligação das poliaminas no receptor N-metil-D-apartato. Neste estudo nós investigamos os efeitos da administração sistêmica de espermidina e arcaína sobre a memória da tarefa de esquiva inibitória em ratos. Também foi determinado se os efeitos da espermidina e arcaína envolvem dependência de estado. Os animais foram treinados em um aparelho de esquiva inibitória (0,4 mA, 3 seg) e testados no mesmo aparelho, 24 horas depois. A administração imediatamente após o treino de espermidina (50 mg/kg, i.p.) melhorou, enquanto que arcaína (10 e 30 mg/kg, i.p.) prejudicou a latência de descida da plataforma no teste da esquiva inibitória. A administração de espermidina (50 mg/kg, i.p.) 15 minutos antes do teste não afetou a performance dos ratos que foram injetados com espermidina (50 mg/kg, i.p.) ou veículo imediatamente após o treino. Entretanto, a administração de arcaína (30 mg/kg, i.p.) 15 minutos antes do teste reverteu o prejuízo da memória causado pela administração de arcaína (30 mg/kg, i.p.) imediatamente após o treino. A administração de arcaína (30 mg/kg, i.p.) ou MK-801 (0,03 mg/kg, i.p.) antes do teste reverteu parcialmente o prejuízo da memória causado pela administração de arcaína (30 mg/kg) ou MK-801 (0,03 mg/kg) imediatamente após o treino, caracterizando dependência de estado cruzada. Estes resultados sugerem que a melhora da memória causada pela administração de espermidina imediatamente após o treino não é devido à dependência de estado. Em contraste, o prejuízo da memória induzido pela arcaína é devido a uma dependência de estado. A dependência de estado cruzada entre arcaína e MK-801. sugere que a dependência de estado induzida pela arcaína envolve a hipofunção do receptor NMDA.
148

Functional Changes in the Gut Microbiome Contribute to Transforming Growth Factor β-Deficient Colon Cancer

Daniel, Scott G., Ball, Corbie L., Besselsen, David G., Doetschman, Tom, Hurwitz, Bonnie L. 26 September 2017 (has links)
Colorectal cancer (CRC) is one of the most treatable cancers, with a 5-year survival rate of similar to 64%, yet over 50,000 deaths occur yearly in the United States. In 15% of cases, deficiency in mismatch repair leads to null mutations in transforming growth factor beta (TGF-beta) type II receptor, yet genotype alone is not responsible for tumorigenesis. Previous work in mice shows that disruptions in TGF-beta signaling combined with Helicobacter hepaticus cause tumorigenesis, indicating a synergistic effect between genotype and microbial environment. Here, we examine functional shifts in the gut microbiome in CRC using integrated - omics approaches to untangle the role of host genotype, inflammation, and microbial ecology. We profile the gut microbiome of 40 mice with/without deficiency in TGF-beta signaling from a Smad3 (mothers against decapentaplegic homolog-3) knockout and with/without inoculation with H. hepaticus. Clear functional differences in the microbiome tied to specific bacterial species emerge from four pathways related to human colon cancer: lipopolysaccharide (LPS) production, polyamine synthesis, butyrate metabolism, and oxidative phosphorylation (OXPHOS). Specifically, an increase in Mucispirillum schaedleri drives LPS production, which is associated with an inflammatory response. We observe a commensurate decrease in butyrate production from Lachnospiraceae bacterium A4, which could promote tumor formation. H. hepaticus causes an increase in OXPHOS that may increase DNA-damaging free radicals. Finally, multiple bacterial species increase polyamines that are associated with colon cancer, implicating not just diet but also the microbiome in polyamine levels. These insights into cross talk between the microbiome, host genotype, and inflammation could promote the development of diagnostics and therapies for CRC. IMPORTANCE Most research on the gut microbiome in colon cancer focuses on taxonomic changes at the genus level using 16S rRNA gene sequencing. Here, we develop a new methodology to integrate DNA and RNA data sets to examine functional shifts at the species level that are important to tumor development. We uncover several metabolic pathways in the microbiome that, when perturbed by host genetics and H. hepaticus inoculation, contribute to colon cancer. The work presented here lays a foundation for improved bioinformatics methodologies to closely examine the cross talk between specific organisms and the host, important for the development of diagnostics and pre/probiotic treatment.
149

Estudo do crescimento celular em culturas embriogênicas e não-embriogênicas de cana-de-açúcar. / Study of cell growth in embryogenic and non-embryogenic cultures of sugarcane.

Ludmila Grechi Fim 14 May 2012 (has links)
Muitos estudos têm sido direcionados para gerar melhorias na cultura de cana-de-açúcar, sendo uma das alternativas o uso de técnicas biotecnológicas, como a embriogênese somática (ES). O objetivo deste projeto foi estudar a multiplicação celular na ES de cana-de-açúcar da variedade SP80-3280. Culturas embriogênicas (CE) e não-embriogênicas (CNE) foram monitoradas e parâmetros bioquímicos foram analisados. Foi observado que CE e CNE apresentaram crescimento máximo aos 24 dias de cultivo, sendo que as CE apresentaram maior incremento em matéria fresca. Dos carboidratos analisados, a sacarose foi predominante em CE, enquanto a glicose predominou em CNE. Os conteúdos de glicose e frutose variaram simultaneamente em CE. As concentrações de amido, poliaminas (Pas) totais e a razão entre PAs [Razão PA= Put/(Spd+Spm)] apresentaram maiores valores nas CNE, sendo a espermidina a poliamina predominante em CE e putrescina em CNE. O conteúdo de proteínas totais foi significativamente maior em CE, em todas as fases de crescimento. / Many studies have been directed to generate improvements in the sugarcane cultures, one of the alternative use of biotechnology techniques such as somatic embryogenesis (SE). The objective of this project was to study the cell multiplication in SE of sugarcane, variety SP80-3280. Embryogenic cultures (EC) and non-embryogenic (NEC) were monitored and biochemical parameters were analyzed. Was observed that EC and NEC showed maximum growth to 24 days of culture, and the EC showed greater increase in fresh weight. Of the carbohydrates tested, sucrose was predominant in EC, while glucose was predominant in the NEC. The contents of glucose and fructose varied simultaneously in EC. The concentrations of starch, polyamines (PAs) and the ratio of total PAs [Ratio PA = Put / (Spd + Spm)] showed higher values in the NEC, and the spermidine is predominant polyamine to EC and putrescine is predominant in NEC. The content of total protein was significantly higher in CE, at all stages of growth.
150

Estudo de regiões genômicas envolvidas no metabolismo de aminoácidos e na determinação da estrutura da parede celular no tomateiro / Study of genomic regions involved in the metabolism of amino acids and in determining cell wall structure in tomato

Fabiana de Godoy 07 June 2013 (has links)
Embora o cultivo de tomate seja muito antigo e amplamente distribuído, ainda enfrenta desafios para o melhoramento dos níveis de produção e, da qualidade para o processamento e consumo fresco. A grande maioria das características de interesse agronômico está determinada por loci de caracteres quantitativos (QTL), dificultando ainda mais a identificação e transferência gênica. Diversas características tornam o tomateiro um bom modelo para estudos de dissecação dos determinantes genéticos de QTL. Primeiro, a disponibilidade de fontes de germoplasma selvagens ainda inexploradas que podem aumentar a variabilidade genética, somada à possibilidade de cruzamento entre espécies não simpátricas e à autogamia. Segundo, a grande quantidade de informação genética como mapas, coleções de ESTs, QTL, e populações de mapeamento. Terceiro, o genoma de S. lycopersicum está completamente sequenciado. Por fim, devido a suas diferenças morfogenéticas em relação à espécie modelo Arabidopsis thaliana, o tomate se torna uma alternativa para estudos de eudicotiledonias, principalmente em estudos relacionadas a metabolismo de frutos carnosos. A partir da abundante plataforma de dados disponível e por meio de ferramentas de genômica, e genética reversa, este trabalho aborda o estudo de duas regiões do genoma do tomateiro envolvidas no metabolismo de aminoácidos e na determinação da estrutura da parede celular. O estudo de genômica comparativa de uma região do cromossomo 7 permitiu revelar a perfeita sintenia existente entre S. lycopersicum e a espécies selvagem S. pennellii e estimar o tempo de divergência em 2,7 MAA. Complementarmente, foi possível determinar que as diferenças fenotípicas entre as espécies são maiormente devidas a mudanças nas regiões regulatórias e à presença de SNPs. O estudo funcional do gene LFP (Low Free Putrescine) permitiu caracterizar uma proteína plastidial, até o momento desconhecida em tomateiro, que participa do metabolismo de poliaminas. O silenciamento de LFP resultou na redução da disponibilidade de putrescina livre e no aumento da biomassa vegetativa. Por outro lado, os resultados obtidos do estudo do gene GAUT4 (galacturonosiltransferase 4) demonstraram que a enzima codificada se localiza em Golgi e participa do metabolismo das pectinas. Em frutos, a redução dos níveis de GAUT4 resultou na diminuição de pectina e na alteração da sua composição, porém estes se apresentaram mais firmes. Adicionalmente, o silenciamento do gene GAUT4 modificou o particionamento de açúcares provocando o aumento de massa vegetativa em detrimento do índice de colheita, revelando assim um mecanismo regulatório que comunica o metabolismo da parede celular ao controle da relação fonte-dreno. Desta forma, os resultados obtidos aportam dados fundamentais para a melhor compreensão de caracteres de interesse agronômico, assim como de processos fisiológicos complexos e pouco explorados até o momento no tomateiro / Although tomato is an old and widely distributed culture, it still faces challenges to improve production levels and quality for processing and consumption. The vast majority of agronomical important characteristics are determine by quantitative trait loci (QTL), further hindering the gene identification and transfer. Several features make tomato a good model for studying the genetic determinants underneath QTL. First, the availability of unexploited sources of wild germplasm that can increase genetic variability, coupled with the possibility of interbreeding between no sympatric species and autogamy. Second, the large amount of available genetic information as maps, EST collections, QTL, and an extensive collection of mapping populations. Third, the genome of S. lycopersicum is completely sequenced. Finally, due to their morphogenetic differences in relation to model species Arabidopsis thaliana, tomato becomes an alternative to eudicotyledons studies, especially in studies related to fleshy fruits metabolism. From the abundant data platform available and by means of genomic tools, and reverse genetics, this work addresses the study of two tomato genomic regions involved in amino acids and cell wall metabolisms. The comparative genomic study in a region of chromosome 7 has revealed the perfect synteny between S. lycopersicum and the wild species S. pennellii, and estimated the time of divergence between both species in 2.7 MYA. Additionally, it was possible to determine that the phenotypic differences between species are mostly due to changes in regulatory regions and the presence of SNPs. The functional study of LFP gene (Low Free Putrescine) allowed us to characterize a plastid protein, yet unknown in tomato, which participates in the metabolism of polyamines. The LFP silencing resulted in reduced availability of free putrescine and increased vegetative biomass. Furthermore, the functional characterization of the GAUT4 (galacturonosyltransferase 4) gene demonstrated that the encoded enzyme is located in the Golgi apparatus and participates in the pectin metabolism. In fruits, the reduced levels of GAUT4 resulted in decreased pectin and in the change of its composition. Additionally, GAUT4 gene silencing modified sugars partitioning leading to an increased vegetative biomass together with a drastic reduction of the harvest index. Thus, revealing a regulatory mechanism that communicates the cell wall metabolism to source-sink relationship control. Concluding, the results obtained contribute to a better understanding of agronomical important traits, as well as of complex physiological processes little explored in tomato so far

Page generated in 0.0608 seconds