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Aplicação de campos elétricos em procedimentos de extração em fase sólida; Application of electric fields in solid phase extraction procedures

Ricardo Mathias Orlando
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/06/2011 PT
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O preparo de amostra representa uma etapa determinante e crítica no processo de análise e a extração em fase sólida (SPE) é uma técnica amplamente empregada no preparo de matrizes complexas. O objetivo deste trabalho foi o desenvolvimento de dispositivos e procedimentos que permitem aplicar campos elétricos em SPE empregando cartuchos (E-SPE®), visando adicionar os mecanismos da eletroforese ao processo cromatográfico. Para tanto, foram desenvolvidos eletrodos e cartuchos que possibilitam a aplicação de campos elétricos, além de um sistema para monitorar e controlar parâmetros eletrocromatográficos tais como: vazão, corrente elétrica, potencial elétrico e temperatura. Com esses dispositivos foram realizadas extrações com aplicação de campo elétrico empregando compostos modelo aniônicos, catiônicos e anfotéricos. Para permitir uma melhor compreensão dos fenômenos envolvidos foram avaliados diversos parâmetros de extração, entre esses: concentração de íons em solução, pH, modificador orgânico, volume de solução de lavagem e tipo de sorvente. O sistema foi avaliado também na determinação de antimicrobianos em leite. Dependendo da polaridade empregada sobre os eletrodos, a aplicação do campo elétrico foi capaz de modular (acelerar ou retardar) a saída dos compostos modelo do cartucho. Os resultados de extração obtidos demonstraram a eficácia dos dispositivos desenvolvidos...

Differential detection of conspecific-derived odorants by the two olfactory epithelia of the Senegalese sole (Solea senegalensis)

Barata, Eduardo N.; Velez, Zélia; Hubbard, Peter C.; Canário, Adelino V.M.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica Formato: 389868 bytes; application/pdf
ENG
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35.76%
The two olfactory epithelia of members of the family Soleidae sample two distinct water sources; the upper (right) side is in contact with the open water column whilst the lower (left) side is in contact with interstitial water. To evaluate whether there are differences in the sensitivities, and therefore functional roles, of the two epithelia the olfactory activity of conspecific-derived odorants was assessed in both using the electro-olfactogram (EOG). The upper nostril was significantly more sensitive to conspecific bile fluid, intestinal fluid and mucus than the lower nostril. Crude fractionation of these samples (solid-phase extraction with C18 and C2/ENV+ cartridges) revealed that olfactory activity in each body fluid was likely due to a mixture of compounds. In each case, the upper olfactory epithelium was significantly more sensitive than the lower. Similarly, olfactory sensitivity to a range of C24 and C27 bile acids was greater in the upper epithelium. These results suggest that intra-specific chemical communication is mediated mainly, if not entirely, by the upper olfactory epithelium. The odorants involved, and their functional roles, remain to be established.

The contribution of amino acids to the odour of a prey species in the Senegalese sole (Solea senegalensis).

Barata, Eduardo N.; Velez, Zélia; Hubbard, Peter C.; Hardege, Joerg; Canário, Adelino V.M.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica Formato: 389868 bytes; application/pdf
ENG
Relevância na Pesquisa
35.76%
For many fish, olfaction is important in food search and consumption. Amino acids are known to elicit feeding behaviour in several species. The aim of the current study was to evaluate the contribution of amino acids to the odour of a natural prey organism of the Senegalese sole (Solea senegalensis). Both whole-body macerates and substances released to the water by living ragworms (Hediste diversicolor) were fractionated by molecular weight filtration followed by solid-phase extraction (SPE), and the olfactory activity of the resultant fractions was assessed by the electro-olfactogram (EOG) in the sole. The amino acid concentrations of the macerate and water were determined by gas chromatography and mass spectrometry (GC–MS). In the macerate, the majority of odorants were small molecular weight compounds (b500 Da) which were not retained by C-18 SPE cartridges. An artificial mixture of amino acids at the same concentrations as found in the macerate had similar olfactory potency. The odorants released to the water by living ragworms were also small molecular weight compounds (b500 Da) but the majority of olfactory activity could be extracted by C-18 SPE cartridges. The concentrations of amino acids in these samples were too low to contribute greatly to its olfactory potency. These results suggest that...

Behavioral and olfactory responses of female Salaria pavo (Pisces: Blenniidae) to a putative multi-component male pheromone

Barata, Eduardo N.; Serrano, Rui M.; Birkett, Michael A.; Hubbard, Peter C.; Guerreiro, Patricia S.; Canário, Adelino V.M.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica Formato: 316093 bytes; application/pdf
ENG
Relevância na Pesquisa
35.76%
The peacock blenny, Salaria pavo (Risso 1810), typically breeds in rocky shores of the Mediterranean and adjacent Atlantic coast. Males defend a territory around a hole or cavity wherein females deposit eggs that the male guards until hatching. A pair of exocrine glands on the anal fin (anal glands) of males produces a putative pheromone involved in attraction of reproductively competent females to the nest. We used behavioral assays to assess species specific attraction of reproductively competent females to putative male pheromones, including the anal gland pheromone. Additionally, chromatographic fractions of anal glands and male-conditioned water were tested for olfactory potency in females by electro-olfactogram analysis (EOG). In a flow-through tank or fluviarium, reproductive females were attracted to male-conditioned water and to the anal gland macerate from conspecifics but not to those of a closely related heterospecific. In addition, attraction of reproductive females to conspecific anal gland macerate occurred only during their initial upstream movement in the fluviarium; this was an ephemeral response when compared with the response to male-conditioned water that attracted females throughout the entire period of observation (5 min). Reproductive females also were attracted during the entire period of observation to water-conditioned by conspecific males whose anal glands had been removed. However...

Prey odour enhances swimming activity and feed intake in the Senegalese sole

Barata, Eduardo N.; Hubert, François; Conceição, Luis E.C.; Velez, Zélia; Rema, Paulo; Hubbard, Peter C.; Canário, Adelino V.M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica Formato: 1084152 bytes; application/pdf
ENG
Relevância na Pesquisa
35.76%
Olfaction is important in many aspects of the life-history of fishes including feeding, and more so in nocturnal benthic feeders. In the current study we assessed the importance of olfaction in food-search behaviour of the Senegalese sole, an economically important marine species both as farmed and wild-caught. Whole-body homogenates of the polychaete Diopatra neapolitana were fractionated by solid-phase extraction (SPE) using C18 cartridges and the olfactory potency of the resultant fractions (hydrophobic eluate and hydrophilic filtrate) was assessed by the electro-olfactogram in juvenile sole. In addition, the effect of both the homogenate and SPE fractions on sole locomotion was assessed in a flow-through tank (fluviarium). Finally, whole-body homogenate was added to commercial feed pellets and tested whether it could enhance food consumption by sole. The SPE hydrophilic filtrate contained the majority of the olfactory activity found in the whole-body homogenate. Both the homogenate and filtrate, but not the eluate, increased number of movements, time moving, linear velocity, distance travelled and time swimming upstream of sole in the fluviarium; ablation of the olfactory epithelia disrupted these behavioural responses to the homogenate. Intact sole consumed more pellets flavoured with worm homogenate than those without. These results show that olfaction plays an important role in food-search behaviour of the Senegalese sole and that the hydrophilic fraction of D. neapolitana whole-body homogenate contains key substances affecting sole search behaviour; moreover...

Functional asymmetry in the olfactory system of a flatfish, the Senegalese sole (Solea senegalensis)

Barata, Eduardo N.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Aula Formato: 100847 bytes; application/pdf
ENG
Relevância na Pesquisa
35.76%
The two olfactory epithelia of the family Soleidae are exposed to different water sources; the upper (right) epithelium samples the water column whereas the lower (left) samples interstitial water. Given that one of the major prey species of the Senegalese sole (Solea senegalensis) is the ragworm Hediste diversicolor which lives in the substrate, we hypothesized that the lower epitheliummay have evolved sensitivity to odorants released by the ragworm whereas the upper epithelium may be more involved in chemical communication and therefore is more sensitive to odorants released by conspecifics. Using a combination of solid-phase extraction, liquid chromatography linked to mass spectroscopy and electrophysiological recording from the olfactory epithelia (the electro-olfactogram), we identified a prey-related odorant (the aromatic amino acid, l-phenylalanine) and a conspecific-related odorant (the bile acid, taurocholic acid). The lower epitheliumwas significantly more sensitive to the former whereas the upper was more sensitive to the latter. Furthermore, cross-adaptation and pharmacological blockade of adenylate cyclase (SQ-22536) and phospholipase C signaling pathways (U73122) suggested that the receptors and transduction mechanisms involved...

Evidence that 1-methyl-L-tryptophan is a food-related odorant for the Senegalese sole (Solea senegalensis)

Barata, Eduardo N.; Velez, Zélia
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica Formato: 639475 bytes; application/pdf
ENG
Relevância na Pesquisa
35.8%
Nocturnal animals often rely heavily on olfactory cues to locate their food. This is especially true for fish whose prey live buried in the substrate. The aim of the current study was to identify odorants released by the ragworm (Hediste diversicolor) that are detected by the olfactory system of the Senegalese sole (Solea senegalensis) and therefore may be food-related cues. Ragworm-conditioned water was passed through a C18 solid-phase extraction cartridge to remove essential amino acids and the eluate fractionated by reverse-phase high-performance liquid chromatography (HPLC). The fractions were then tested for olfactory activity in the sole by the electro-olfactogram (EOG). Most olfactory activity was found in the first two fractions to elute from the HPLC column (0-4 minutes). Liquid chromatography-mass spectrometry (LC/MS) of both fractions revealed a base peak with a molecular mass of 219.4 Da and a fragment of 205.3 Da. These data are consistent with a methylated form of tryptophan; synthetic 1-methyl-L-tryptophan had a similar HPLC retention time (2.8 minutes) and similar LC/MS spectra. Furthermore, sole showed olfactory sensitivity to 1-methyl-L-tryptophan with the lower (left) epithelium being more sensitive than the upper (right). Cross-adaptation (using EOG recording) suggested that the olfactory receptors responding to 1-methyl-L-tryptophan are different in the lower epithelium from the upper. These results suggest that ragworms release 1-methyl-L-tryptophan...

Neural Mechanisms of olfactory discrimination in the Senegalese sole, Solea senegalensis Kaup, 1858

Velez, Zélia Cristina Pereira
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
35.86%
O ambiente aquático é frequentemente escuro e turvo, tal leva a que muitos peixes e outros organismos não utilizem a visão como principal sentido de orientação. No entanto, este ambiente é geralmente rico em diferentes compostos químicos que se encontram dissolvidos na água, o que faz com que muitos organismos tenham os sentidos químico-sensoriais muito desenvolvidos, especialmente espécies nocturnas e/ou que habitam águas de elevada turbidez. O linguado Senegalês é um peixe bentónico pertencente ao grupo dos peixes chatos (Pleuronectiformes). Tal como a maioria dos peixes deste grupo o linguado passa grande parte do tempo parcialmente enterrado na areia, ficando apenas com os olhos e a narina superior expostos à coluna de água. As principais presas desta espécie são organismos bentónicos que vivem enterrados na areia, tais como poliquetas e crustáceos. Durante a metamorfose, o olho esquerdo migra para o lado superior (direito), no entanto, a narina esquerda não migra permanecendo no lado inferior (esquerdo). Em consequência, os dois epitélios olfactivos do linguado encontram-se expostos a diferentes ambientes; a narina superior amostra a coluna de água, enquanto a narina inferior amostra a água intersticial. Alguns odorantes são detectados de forma diferencial pelos dois epitélios olfactivos...

Chemical communication in the reproduction of the peacock blenny, Salaria pavo (Pisces: Blenniidae)

Serrano, Rui M.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Tese de Doutorado Formato: 8870017 bytes; application/pdf
ENG
Relevância na Pesquisa
35.99%
The peacock blenny Salaria pavo (Risso, 1810) is a small bottom-living teleost found in the littoral zone of the Mediterranean sea and adjacent Atlantic coast. Males occupy holes or crevices in rocks where females come to spawn and the males subsequently guard the eggs. Males develop anal glands from the epidermis of the first two rays of the anal fin concurrent with development of the gonads. It has previously been shown that this gland is the source of putative sex pheromones that attract females in reproductive condition. Males also possess accessory reproductive organs (testicular glands and blind pouches) which may also produce sex pheromones. This study aimed to test whether male S. pavo have evolved a specialization in the way they produce and release pheromonal signal(s), providing an example where true chemical communication has evolved in fish. Four experimental chapters attempt to answer specific questions. The main results and conclusions of the experiments are summarized as follows. Behavioural and olfactory responses of female Salaria pavo (Pisces: Blenniidae) to putative pheromones from the anal gland of males A pair of anal glands on the anal fin of male Salaria pavo is suggested to be a specialised structure for the production/release of (a) putative sex pheromone(s) that attracts females and affects their mate choice. However...

Nuevas metodologías de análisis de pesticidas por electroforesis capilar

Hernández Borges, Javier
Fonte: Universidad de La Laguna Publicador: Universidad de La Laguna
Tipo: Tesis Formato: 5478351 bytes; application/pdf
SPA
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35.87%
Tesis Doctoral de la Universidad de La Laguna, Departamento de Química Analítica, Nutrición y Bromatología, y del Instituto de Fermentaciones Industriales (IFI-CSIC).-- Fecha de lectura: 15-12-2005.; [EN] This PhD Thesis has been developed following one of the research lines of our research group “Chemical analysis applied to the industry, environment and agroalimentary products”. In this research line we develop fast and clean analytical methodologies that allow the determination of pesticides in agroalimentary and environmental samples. Following this research line, the main objective of this Thesis has been the development of new analytical methods for the analysis of pesticides by capillary electrophoresis. The main objective covers the following more concrete goals: (i) To increase the senstivity and selectivity of CE methodologies, by developing more economical and clean preconcentration techniques as, for instance, solid-phase microextraction (SPME) or solid-phase extraction (SPE), for the analysis of pesticides in different sample of environmental interest. (ii) To investigate different on-line preconcentration strategies to increase the sensitivity obtained by CE. (iii) To study the use of different detectors (UV...