Egg activation is a series of highly coordinated processes that prepare the mature oocyte for embryogenesis. Typically associated with fertilisation, egg activation results in the resumption of the cell cycle, expression of maternal mRNAs and cross-linking of the vitelline membrane. While some aspects of egg activation, such as initiation factors in mammals and environmental cues in sea animals, have been well-documented, the mechanics of egg activation in many animals are still not well understood. This is especially true for animals where fertilisation and egg activation are unlinked. In order to elucidate how egg activation is regulated independently of fertilisation, I use Drosophila melanogaster as a model system. This insect provides extensive genetic tools, ease of manipulation for experimentation and is amenable for imaging. Through visualisation of calcium, Processing bodies and meiotic spindles, I show that osmotic pressure acts as an initiation cue for the calcium wave and downstream processes, including the resumption of cell cycle and the dispersion of the translational repression sites. I further show that aquaporin channels, together with external sodium ions, play a role in coordinating swelling of the oocyte in response to the osmotic pressure. I proceed to identify the requirement of internal calcium sources together with a dynamic actin cytoskeleton for a calcium wave to occur. Through co-visualisation of calcium and actin, I provide the first evidence that the calcium wave is followed by a wavefront of non-cortical F-actin at egg activation, which requires the calcium wave. Genetic analysis supports a model where changes in osmotic pressure trigger the calcium wave via stretch sensitive calcium channels in the oocyte membrane and the calcium wave is relayed by nearby channels via the actin cytoskeleton. My work concludes that the mechanism of egg activation in Drosophila is more similar to plants, compared to most vertebrates.

O estudo consistiu em quatro experimentos com o objetivo de avaliar a redução proteica e níveis de metionina+cistina sobre o desempenho e qualidade de ovos (produção de ovos, consumo de ração, conversão alimentar, peso de ovo e fatores de qualidade dos ovos, unidade Haugh, espessura de casca, resistência à quebra, pigmentação de gema, gravidade específica) de poedeiras comerciais leves e semipesadas de 24 a 40 semanas de idade. Em cada experimento, foram utilizadas 240 poedeiras comerciais distribuídas em delineamento inteiramente casualisado com 8 aves por unidade experimental com 10 repetições. Os níveis dos aminoácidos, treonina, triptofano e valina foram mantidos os mesmos em todos os tratamentos através da suplementação de aminoácidos sintéticos. No primeiro e segundo experimentos avaliaram-se três níveis de proteína bruta (15,4%, 16,4% e 17,4%) em dietas para aves leves (experimento I) e aves semipesadas (experimento II) das linhagens Bovans White e Bovans Brown, respectivamente. No experimento I não foram observadas diferenças estatísticas para os parâmetros relacionados à qualidade da casca do ovo, nem mesmo para altura de albúmen e peso do ovo. A redução do nível proteico da dieta para 16,4% não afetou o desempenho das poedeiras leves (P<0,05). No experimento II, não houve diferenças estatísticas para os parâmetros avaliados. Nos experimentos III e IV avaliou-se o efeito de dois níveis de proteína bruta (16,4% e 17,4%) e dois níveis metionina+cistina (0,66% e 0,77) em dietas para aves leves (experimento III) e aves semipesadas (experimento IV) das linhagens Bovans White e Bovans Brown. No experimento III a qualidade de ovo não foi influenciada pelos tratamentos. Houve interação entre os níveis de proteína bruta e aminoácidos sulfurados para as variáveis de produção de ovos, consumo de ração e conversão alimentar por dúzia de ovos. As aves alimentadas com a dieta com 15,4% de proteína bruta apresentaram menor produção de ovos quando comparado às aves que receberam dietas com níveis de AAST elevados e com PB elevada. As aves alimentadas com 17,4% de PB e 0,77% de aminoácidos sulfurados apresentaram maior consumo e pior conversão alimentar (P<0,05). O aumento no nível de AAST resultou em maior peso do ovo. No experimento IV houve interação entre os fatores estudados, sendo que as aves alimentadas com níveis mais baixos de PB e AAST (16,4% e 0,66%, respectivamente), apresentaram menor produção de ovos e pior conversão alimentar. Para a variável peso de ovos, houve efeito dos níveis de AAST, sendo que as aves alimentadas com 0.77% produziram ovos com maior peso (P<0,05). / The study consisted of four experiments to evaluate the effect of protein and reduced levels of methionine+cystine on the performance and egg quality (egg production, feed intake, feed conversion, egg weight and egg quality factors, Haugh unit, shell thickness, breaking strength, yolk pigmentation) of light and semi heavy weight laying hens with 24-40 weeks of age. In each experiment 240 laying hens were distributed in a completely randomized design with 8 birds per experimental unit with 10 replicates. Levels of, threonine, tryptophan and valine were kept the same in all treatments by supplementation of synthetic aminoacid. In experiments I and II were evaluated three levels of crude protein (15.4%, 16.4% and 17.4 %) on diets for light Bovans White hens (experiment I) and Bovans Brown semi heavy weight (experiment II). In the first experiment there was no statistical differences in the parameters related to the quality of the egg shell, even for albumen height and egg weight were observed. The reduction of the protein level of the diet to 16.4% did not affect the performance of laying hens (P<0.05). In experiment II there were no statistical differences in the parameters evaluated. In experiments III and IV evaluated the effect of two levels of crude protein (16.4% and 17.4%) and two methionine + cystine levels (0.66% and 0.77%) on diets for light Bovans White hens (experiment III) and Bovans Brown semi heavy weight (experiment IV). In experiment III the egg quality was not affected by treatments. There was interaction between the levels of crude protein and sulfur aminoacids for the variables of egg production, feed intake and feed conversion per dozen eggs. Hens fed diets with lower protein levels had lower egg production when compared to hens fed diets with high levels of TSAA and high CP. Hens fed with diets with 17.4% of CP and 0.77% of sulfur aminoacids had higher intake and worse feed conversion (P<0.05). The increase in the level of TSAA resulted in higher egg weight. In experiment IV there was interaction between the factors studied, where lower levels of CP and TSAA (16.4% and 0.66 %, respectively), had lower egg production and lower feed conversion. For egg weight, there was effect of TSAA. Hens fed diets with 0.77% of TSAA produced heavier eggs (P<0.05).

The aim of this research was to identify the molecular mechanisms that promote spontaneous activation in rat eggs after their recovery from the oviduct. Typically, mammalian eggs await fertilisation arrested at the second metaphase II of meiosis. However, ovulated rat eggs spontaneously enter anaphase II when exposed to in vitro culture. After extrusion of the second polar body, these spontaneously activated eggs do not proceed to interphase but become arrested at metaphase III stage with chromatids scattered in the egg cytoplasm. This instability may be one factor that has made it more difficult to establish reliable protocols for somatic cell nuclear transfer in rats. The triggers of spontaneous activation and signalling pathways leading to the metaphase III progression are largely unknown. Analyses of signalling pathways that are involved in the regulation of final stages of meiosis during fertilisation revealed several anomalies that were associated with spontaneous activation and the transition from metaphase II to metaphase III. Metaphase II arrested eggs usually exhibit an increased level of maturation promoting factor (MPF) activity. Spontaneous activation in rat eggs was associated with a drop in MPF activity at the time of the second polar body extrusion. MPF is composed of a catalytic subunit, CDK1, and a regulatory subunit, cyclin B1. Interestingly, the level of cyclin B1 was stable throughout spontaneous activation. Post-translational modifications of CDK1 can influence MPF activity: whereas no inhibitory phosphorylation on Tyr15 of CDK1 was found; a decrease in activating Thr161 phosphorylation of CDK1 was associated with the time of the second polar body extrusion, and hence could contribute to the transient MPF inactivation. MAPK (p42/p44) activity has been shown to decrease during egg activation in fertilisation. By contrast, during spontaneous activation, MAPK (p42/p44) remained active and thus resembled the profile usually found between two meiotic divisions (metaphase I to metaphase II). Securin, a protein which prevents premature chromatid separation, was degraded in eggs going through spontaneous activation. Cytostatic factor (CSF) is a biochemical activity, which enables stable metaphase II arrest in ovulated eggs of vertebrates. Recently, the endogenous meiotic inhibitor 2, EMI2, was confirmed as the major component of CSF. For egg activation to occur, the CSF must be destroyed. At the beginning of egg activation, Ca2+/calmodulin kinase (CaMKII) promotes posttranslational modifications of EMI2, leading to its degradation. In the rat, inhibition of CaMKII activity stably prevented the onset of spontaneous activation in a subset of metaphase II eggs. However, no degradation of EMI2 protein was found at the start of abortive metaphase II exit. This finding revealed that one of the central elements of the CSF pathway, EMI2, could be preserved in the rat eggs going through spontaneous activation. In order to study the mechanisms regulating EMI2 stability in rat oocyte maturation and spontaneous activation, functional analysis of ectopically expressed synthetic mRNA was performed. The mechanism enabling EMI2 degradation became active 12 hours after the start of oocyte maturation. The C-terminal fragment of EMI2, known to be non-degradable in Xenopus oocyte maturation, was significantly more stable than the full-length counterpart in matured rat eggs but not during oocyte maturation. Interestingly, C-terminal EMI2 became degraded in parthenogenetic rat embryos. This indicated that additional not previously reported mechanisms responsible for EMI2 degradation might exist in the rat. The microinjection of metaphase II rat eggs with the C-terminal fragment of EMI2 or IVT full-length EMI2 protein had little effect on the progression of spontaneous activation. Taken together, these observations suggest that abortive spontaneous activation in rat eggs was a result of incomplete engagement of signalling pathways normally triggered in fertilisation or parthenogenetic activation. Activation of CaMKII initiated pathways that allowed anaphase entry and chromatid segregation. At the same time, not all pathways normally triggered during fertilisation or parthenogenetic activation were fully engaged, possibly due to the presence of non-degraded component of CSF. Abortive incomplete activation results in the re-establishment of high level of MPF activity in metaphase III eggs. Early prevention of CaMKII activation, perhaps by blocking [Ca2+ i] signalling, may provide a means of holding ovulated eggs at metaphase II prior to enucleation and somatic cell nuclear transfer.

Orientador: Edivaldo Antonio Garcia / Banca: Lúcio Francelino Araújo / Banca: Ricardo de Albuquerque / Resumo: Com o objetivo de comparar níveis de cálcio e fósforo durante toda a fase de produção, foi realizado um experimento utilizando-se 720 codornas japonesas (Coturnix coturnix japonica) com 7 semanas de idade. O período experimental teve duração de 48 semanas e utilizou-se quatro níveis de cálcio (2,0; 2,5; 3,0 e 3,5%) e três níveis de fósforo (0,25; 0,35 e 0,45%) divididos em 12 tratamentos com 6 repetições cada. O experimento foi dividido em 3 fases: período inicial de produção (4 primeiros ciclos de 28 dias: 7 a 22 semanas de idade), período intermediário (4 ciclos de 28 dias: 23 a 38 semanas de idade) e período final de produção (os últimos 4 ciclos de 28 dias: 39 a 54 semanas de idade). O desempenho das aves e a qualidade dos ovos foram avaliados ao final de cada ciclo de 28 dias, e teores de cálcio e fósforo presentes no plasma, ao final do período experimental (54 semanas de idade). Concluiu-se que independente da fase de produção, as exigências nutricionais de cálcio e fósforo para codornas japonesas em postura que proporcionam bom desempenho produtivo e manutenção satisfatória da qualidade dos ovos são de 2,5% e 0,25%, respectivamente / Abstract: With the objective to compare levels of calcium and phosphorus during all the production phase, was conducted an experiment using 720 Japanese quails (Coturnix coturnix japonica) with 7 weeks of age. The experimental period lasted 48 weeks, and used four levels of calcium (2.0; 2.5; 3.0 e 3.5%) and three levels of phosphorus (0.25; 0.35 e 0.45%) divided into 12 treatments with six replicates. The experiment was divided into three phases: initial production phase (the first 4 cycles of 28 days: 7 to 22 weeks), intermediate phase (4 cycles of 28 days: 23 to 38 weeks) and the final production phase (the last 4 cycles of 28 days: 39 to 54 weeks). The bird performance and egg quality were evaluated after each cycle of 28 days, and grades of calcium and phosphorus in the plasma, at the end the experimental period (54 weeks). It was concluded that regardless of production phase, the nutritional requirements of calcium and phosphorus to Japanese cleaned common quails in posture that provide good performance productive and satisfactory maintenance of the quality of eggs are 2.5% and 0.25% respectively / Mestre

Orientador: Carlos Ducatti / Resumo: Estudos avícolas usando isótopos estáveis como traçadores em suas dietas fornecem estimativas de quão rapidamente os isótopos estáveis dos tecidos são substituídos por isótopos derivados da dieta. Estabeleceu-se taxas de turnover, meia-vida e substituição total do 13C no sangue, ovo (albúmen + gema), albúmen e gema de aves de postura, pela troca de dietas compostas de plantas dos ciclos fotossintéticos C3 e C4. E avaliou o efeito das dietas quanto ao fracionamento isotópico dieta-tecido e bromatologia do albúmen e da gema. O turnover é influenciado pela qualidade da dieta oferecida a ave. A comparação entre as meias-vidas do sangue, ovo, gema e albúmen, respectivamente, mostra que a dieta RC4 apresentou valores de meia-vida maiores que os outros tratamentos (RC4 = 13,3; 4,8; 5,5 e 5,2d; RC3 = 5,3; 3,8; 4,5 e 2,5d; RMC4 = 10,5; 3,8; 4,8 e 3,2d e RMC3 = 9,2; 3,5; 4,6 e 1,5d). Os tecidos estudados, pelo fato de apresentarem baixo fracionamento isotópico (?dieta-tecido = 0,1 l 0,5%), refletem bem a dieta consumida. Quanto a bromatologia da gema e albúmen não encontrou diferença significativa. / Abstract: Poultry studies using stable isotopes as tracers in their diets supply information of how fast the stable isotopes from tissues are replaced by those diet-derivated. Established turnover rates, half-life and 13C total replacement in blood, egg (albumen + yolk), albumen and egg yolk from lay hens, through exchanging diets composed of C3 and C4 photosynthetic cycle plants. It also evaluated the effect of diets with regard to diet-tissue isotopic fractionation and bromatology of albumen and egg yolk. Turnover is influenced by quality of the diet used to feed the hens. The comparison among the half-lives of the blood, egg, yolk and albumen, respectively, shows that the diet RC4 presented half-life values higher than the other treatments (RC4 = 13,3; 4,8; 5,5 and 5,2days; RC3 = 5,3; 3,8; 4,5 and 2,5days; RMC4 = 10,5; 3,8; 4,8 and 3,2days and RMC3 = 9,2; 3,5; 4,6 and 1,5days). The studied tissues, due to the fact of presenting low isotopic fractionation (?diet-tissue = 0,1 l 0,5%), reflect well the diet intook. With relation to the albumen and yolk bromatology, none significant difference was found. / Mestre

O ovo é o produto de eficiente transformação biológica feita pela galinha (Gallus gallus) de postura, com alta qualidade nutricional para o consumo humano. Na gema do ovo encontra-se a proteína denominada fosvitina, a mesma atua como carreadora do ferro se ligando a ele. A deficiência de ferro ocorre normalmente devido ao consumo insuficiente de alimentos fontes de ferro ou a baixa biodisponibilidade. O objetivo desta pesquisa foi verificar a concentração de proteínas, em especial a fosvitina/lipovitelina presente em gemas de ovos crus e cozidos nos diferentes ciclos de postura (inicial, intermediário e final) e avaliar a interferência desta proteína na disponibilidade do micronutriente ferro. Os tratamentos foram realizados em diferentes períodos e utilizaram-se ovos crus e cozidos, sendo gemas cruas de poedeiras em início, meio e fim de postura e gemas cozidas nos três ciclos de postura. Foram realizadas as análises de composição centesimal, concentração de ferro total e dialisável, concentração de proteínas em gemas e eletroforese em gel de poliacrilamida (SDS-PAGE). Houve diferença na concentração de proteínas e diferentes níveis de ferro dialisável nos três ciclos de postura, porém em gemas cruas e cozidas. Com o passar dos ciclos (inicial, intermediário e final), as poedeiras mais velhas, apresentaram gemas com teor mais elevado de ferro disponível, porém uma quantidade inferior de proteínas em especial a fosvitina/lipovitelina, comparando-se com os ciclos inicial e intermediário. A disponibilidade de ferro foi mais elevada em gemas que passaram pelo processo de cocção, porém em poedeiras de postura final. / The egg is the product of efficient biological transformation made by the hens of position, with high nutricional quality for the human consumption. In the egg yolk of the egg it meets phosvitin called protein, the same one acts as hauled of the iron if binding it. The iron deficiency normally occurs due to the insufficient food consumption iron sources or low the bioavailability. The objective of this research was to verify the protein concentration, in special the present phosvitin/lipovitelin in egg yolks of raw eggs and stews in the different cycles of position (initial, intermediate, end) and to evaluate the interference of this protein in the availability of the micronutrient iron. The treatments had been carried through in different periods and had used raw eggs and cooked, being raw egg yolks of hens in initial, intermediate and end of position and egg yolks boil in the three cycles of position. The analyses of proximal composition had been carried through, concentration of total and availability iron, protein concentration in egg yolks and electrophoresis in poliacrilamide (SDS-PAGE) were carried. It had difference in the protein concentration and different levels of iron availability in the three cycles of position, however in raw and boiled egg yolks. With passing of the cycles (initial, intermediate, end), the hens oldest, had more presented egg yolks with a raised amount of available iron, however special amount of proteins in the fosvitina/lipovitelina, comparing themselves with the cycles initial and intermediate. The iron availability more was raised in egg yolks that had passed for cooking process, however in hens of final position.

O uso de praguicidas na agricultura e pecuária pode acarretar sérios problemas à saúde dos seres humanos e dos animais. O controle da presença destas substâncias nos alimentos e no meio ambiente são um instrumento importante para minimizar o risco da exposição a estas substâncias. No Brasil, as informações sobre resíduos de praguicidas são insuficientes, especialmente quando se trata de produtos de origem animal. Um importante nutriente na dieta dos seres humanos é o ovo, principalmente na dieta infantil. De acordo com a FAO o Brasil ocupa o 7° lugar na produção de ovos com 1,72 milhões de dúzias por ano e um consumo per capita de 1,7 kg/ano (IBGE, 2003). Embora o consumo de ovos no Brasil seja um aspecto importante a maior parte da produção é exportada para outros países, principalmente, Arábia Saudita, China, Japão e Holanda. Este estudo foi desenvolvido no período de Janeiro de 2004 a Dezembro de 2006, um total de 150 amostras de ovos foram coletadas no mercado e avaliadas para a presença de resíduos de praguicidas organoclorados, organofosforados e piretróides. O método utilizado nas analises para determinar os resíduos de praguicidas nas amostras foi o DFG S19. Este método consiste em extração com solvente orgânico, etapa de partição com diclorometano e purificação com o emprego de cromatografia de permeação a gel e mini-coluna de sílica gel. Para a identificação e quantificação foi utilizada a metodologia analítica de cromatografia gasosa com detectores de captura de elétrons, nitrogênio/fósforo e fotométrico de chama. Os estudos de recuperação estiveram dentro da faixa de 70 a 120%. Os resultados das analises mostraram que o herbicida alacloro foi detectado em 0,7% das amostras analisadas e a sua contribuição para a ingestão diária crônica foi avaliada. Este praguicida não possui LMR em ovo, assim como o parâmetro de ingestão diária aceitável não foi estabelecido, porém a presença em ovo pode ser atribuída a alimentação dos animais e este praguicida devido a presença de cloro na molécula pode contribuir para o risco crônico à saúde humana. Embora apenas uma amostra tenha tido um resultado positivo, o controle dos alimentos destinados a população são um importante fator a ser controlado para garantir a saúde da população. / The use of pesticides in agriculture and livestock can cause serious problem for human beings and animal health. The control of these substances in food and in the environment is an important instrument to minimize these risks. In Brazil information about pesticide residues on food are insufficient, especially for animal products. An important nutrient supply on human diet is the egg, it provides several nutrients especially for children. According to FAO Brazil is the 7th in world ranking production and produces 1.72million dozen/year and the consumption is around 1.7 kg/year (IBGE, 2003). Despite of the Brazilian scene the consumption per capita almost of egg production is exported to other countries and the main countries are Saudi Arabia, China, Japan and Netherlands. The study was developed from January 2004 to 2006, 150 egg samples were collected from the national market and evaluated for pesticide residues of organochlorine, organophosphorus and pyrethroids pesticides. A multiresidue method were employed to determinate the pesticide in samples. The method uses an organic solvent extraction, a partition with dichloromethane and purification step by gel permeation chromatography (GPC) and silica gel column. For identification and quantification it was used gas chromatography techinique with ECD, NPD and FPD detectors. The recoveries for the method were within 70 to 120%. The results of the analysis showed that the herbicide alachlor were detected in 0.7% of the samples and the chronic dietary intake was evaluated. The pesticide does not have a proper use in egg, no MRL established and no ADI parameter. The presence could be attributed to feed contamination and the contribution to health risk could be detached once it has a chlorine molecule which could contribute to chronic diseases. Although only one sample was positive to pesticide residues this result is important to food quality control and consumer health. It helps to emphasize the risk studies on pesticide residues on animal and vegetable food.

A perda de qualidade de ovos é um processo inevitável e contínuo ao longo do tempo. Existem legislações vigentes no Brasil quanto à temperatura e estocagem de ovos comerciais, no entanto ainda são necessárias pesquisas sobre a vida de prateleira de ovos provenientes do sistema orgânico. O trabalho teve como objetivo avaliar vida de prateleira de ovos, oriundos de poedeiras de produção orgânica, em diferentes idades de postura, considerando a qualidade externa e interna do ovo. Os ovos foram coletados em uma granja com certificação de produção orgânica do município de Viamão- RS. O delineamento experimental foi inteiramente casualizado em fatorial 6x4 - 6 idades de postura x 4 períodos de armazenamento. Foram coletados 288 ovos de aves semi-pesadas em diferentes idades de postura (40, 50, 60, 70, 80 e 90 semanas), e as avaliações de qualidade foram realizadas aos zero (dia da coleta), 14, 28 e 42 dias de armazenamento. Cada período de armazenamento possuía 12 repetições e os ovos foram estocados em sala com controle de umidade (70 ± 4 %) e temperatura (14 ± 2°C). Os ovos foram pesados no dia da coleta e nos dias de avaliação para identificação da perda de peso ao longo do armazenamento As variáveis analisadas foram: peso do ovo, unidade Haugh, altura do albúmen, porcentagem de albúmen, gema e casca do ovo, estabilidade da espuma do albúmen, espessura da casca, pH do albúmen e perda de peso dos ovos. Houve interação da idade da ave e o período de armazenamento (P<0,05) dos tratamentos avaliados sobre a perda de peso do ovo. Poedeiras jovens (40 semanas de idade) apresentam melhor qualidade interna dos ovos com menores perdas de qualidade quando comparadas a aves com 50 e 60 semanas de idade durante o armazenamento por até 42 dias. A estabilidade da espuma do albúmen é melhor em aves mais velhas. O pH do albúmen não é afetado pela idade das poedeiras, mas apresenta aumento significativo em maiores períodos de armazenamento. A vida de prateleira de ovos de produção orgânica pode ser estendida até os 42 dias de armazenamento. Os ovos provenientes de poedeiras mais velhas apresentam qualidade interna superior nos primeiros dias de estocagem, porém com alta susceptibilidade de perdas durante o armazenamento por até 42 dias. / The loss of quality in egg is an inevitable and continuous process over time. There are laws in force in Brazil regarding the temperature and storage of commercial eggs, however, it is still necessary to research on the shelf life of eggs from the organic system. The objective of this work was to evaluate the shelf life of eggs from organic laying hens at different ages, considering the external and internal quality of the egg. The eggs were collected in a farm with certification of organic production of the municipality of Viamão - RS. The experimental design was completely randomized in factorial 6x4 - 6 posture ages x 4 storage periods. A total of 288 eggs were collected at different ages (40, 50, 60, 70, 80 and 90 weeks), and quality evaluations were performed at zero (day of collection), 14, 28 and 42 days of storage. Each storage period had 12 replicates and the eggs were stored in a room with humidity control (70 ± 4%) and temperature (14 ± 2 ° C) The eggs were weighed on the day of collection and on the evaluation days to identify weight loss throughout storage. The variables analyzed were: egg weight, Haugh unit, albumen height, albumen percentage, egg yolk and egg shell, albumen foam stability, shell thickness, albumen pH and egg weight loss. There was interaction between the age of the fowl and the storage period (P <0.05) of the evaluated treatments on egg weight loss. Young laying hens (40 weeks of age) show better internal quality of eggs with lower quality losses when compared to birds at 50 and 60 weeks of age during storage for up to 42 days. The stability of albumen foam is best in older birds. The pH of the albumen is not affected by the age of laying hens, but presents a significant increase in longer periods of storage. The shelf life of organic production eggs can be extended up to 42 days of storage. Eggs from older laying hens have superior internal quality in the first days of storage, but with high susceptibility of losses during storage for up to 42 days.

This work investigated the design parameters necessary for the build and use of an in vitro artificial mouth model built for dental erosion research. It also ascertained the working knowledge of dentists concerning the Human Tissue Act (HTA) and explored an alternative tissue for erosion-testing to human enamel. The design inputs for the artificial mouth were acquired by an innovative observational study conducted upon human volunteers and used in the decisions made in the setting of the fluids’ kinematic behaviour and how the associated devices were to function. This novel system was sought to mimic the interaction of saliva and the dental substrate during the process of consuming an erosive beverage. The model allows researchers to gather data using customizable experimental diets without the technical burden of dealing with a non-realistic regime. The design and build of the artificial mouth model along with its associated equipment and parameters are described and a manual for operation of the model is appended. The device is designed on a fully adjustable multitask basis in which the operator can set several variables such as the desirable salivary kinematic behaviour, offensive beverage flow rate, and volume of consumption. This, subsequently, allows the samples preloaded on the system to be tested for surface characteristics (i.e. surface hardness and surface profilometry) to determine the extent of erosion if any. The model also allows the resultant solution to be analysed for traces of calcium and phosphate ions. To validate the capabilities of the artificial mouth system a set of diets was performed repeatedly. The high degree of agreement and the consistency of results showed that the model is able to mimic realistic scenarios and is capable of producing reliable, reproducible and accurate outcomes. Ostrich eggshell proved to be a potential alternative erosion substrate which is fortuitous as the lack of knowledge on the HTA had meant human enamel was less readily available.

O uso de praguicidas na agricultura e pecuária pode acarretar sérios problemas à saúde dos seres humanos e dos animais. O controle da presença destas substâncias nos alimentos e no meio ambiente são um instrumento importante para minimizar o risco da exposição a estas substâncias. No Brasil, as informações sobre resíduos de praguicidas são insuficientes, especialmente quando se trata de produtos de origem animal. Um importante nutriente na dieta dos seres humanos é o ovo, principalmente na dieta infantil. De acordo com a FAO o Brasil ocupa o 7° lugar na produção de ovos com 1,72 milhões de dúzias por ano e um consumo per capita de 1,7 kg/ano (IBGE, 2003). Embora o consumo de ovos no Brasil seja um aspecto importante a maior parte da produção é exportada para outros países, principalmente, Arábia Saudita, China, Japão e Holanda. Este estudo foi desenvolvido no período de Janeiro de 2004 a Dezembro de 2006, um total de 150 amostras de ovos foram coletadas no mercado e avaliadas para a presença de resíduos de praguicidas organoclorados, organofosforados e piretróides. O método utilizado nas analises para determinar os resíduos de praguicidas nas amostras foi o DFG S19. Este método consiste em extração com solvente orgânico, etapa de partição com diclorometano e purificação com o emprego de cromatografia de permeação a gel e mini-coluna de sílica gel. Para a identificação e quantificação foi utilizada a metodologia analítica de cromatografia gasosa com detectores de captura de elétrons, nitrogênio/fósforo e fotométrico de chama. Os estudos de recuperação estiveram dentro da faixa de 70 a 120%. Os resultados das analises mostraram que o herbicida alacloro foi detectado em 0,7% das amostras analisadas e a sua contribuição para a ingestão diária crônica foi avaliada. Este praguicida não possui LMR em ovo, assim como o parâmetro de ingestão diária aceitável não foi estabelecido, porém a presença em ovo pode ser atribuída a alimentação dos animais e este praguicida devido a presença de cloro na molécula pode contribuir para o risco crônico à saúde humana. Embora apenas uma amostra tenha tido um resultado positivo, o controle dos alimentos destinados a população são um importante fator a ser controlado para garantir a saúde da população. / The use of pesticides in agriculture and livestock can cause serious problem for human beings and animal health. The control of these substances in food and in the environment is an important instrument to minimize these risks. In Brazil information about pesticide residues on food are insufficient, especially for animal products. An important nutrient supply on human diet is the egg, it provides several nutrients especially for children. According to FAO Brazil is the 7th in world ranking production and produces 1.72million dozen/year and the consumption is around 1.7 kg/year (IBGE, 2003). Despite of the Brazilian scene the consumption per capita almost of egg production is exported to other countries and the main countries are Saudi Arabia, China, Japan and Netherlands. The study was developed from January 2004 to 2006, 150 egg samples were collected from the national market and evaluated for pesticide residues of organochlorine, organophosphorus and pyrethroids pesticides. A multiresidue method were employed to determinate the pesticide in samples. The method uses an organic solvent extraction, a partition with dichloromethane and purification step by gel permeation chromatography (GPC) and silica gel column. For identification and quantification it was used gas chromatography techinique with ECD, NPD and FPD detectors. The recoveries for the method were within 70 to 120%. The results of the analysis showed that the herbicide alachlor were detected in 0.7% of the samples and the chronic dietary intake was evaluated. The pesticide does not have a proper use in egg, no MRL established and no ADI parameter. The presence could be attributed to feed contamination and the contribution to health risk could be detached once it has a chlorine molecule which could contribute to chronic diseases. Although only one sample was positive to pesticide residues this result is important to food quality control and consumer health. It helps to emphasize the risk studies on pesticide residues on animal and vegetable food.