RESUMO
This study carried out migration investigations with different spiked and non-spiked paper and board packaging materials in contact with foodstuffs and food simulants in the temperature range between -18 degrees C and 40 degrees C. The aim was to deepen the understanding of the migration behaviour of target substances in paper and board fibres. Components and contaminants of paper and board with different molecular weight and chemical structure were selected as target migrants. From the kinetic migration studies, diffusion and partition coefficients were derived by using software for modelling migration in multilayer materials. On the basis of these results, for the first time a model for the migration from paper and board into foods and simulants was developed by adapting the validated diffusion model for plastics. In contrast to the migration in plastic materials, where the migrants are solved and homogeneously distributed in the polymer matrix, mass transfer in paper and board is a more complex phenomenon, because the migrants can be adsorbed on the cellulose surface with different strength. The most important finding of the study was that for a correct modelling of the experimental results in many cases paper and board must be regarded as a two-layer system: the main mass of paper and board (B1) defines the core layer with high diffusion rates, and a thin second layer (B2) represents the surface region of the paper and board with decreased diffusion rates due to the slow desorption.
Assuntos
Indústria Alimentícia , Modelos Teóricos , Papel , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , TemperaturaRESUMO
We describe a comparative lung expression analysis of the murine Irx1 and Irx2 genes. At embryonic day 8.5 (E8.5), the Irx1 and Irx2 expression starts in the foregut region, where the laryngo-tracheal groove will form. The expression is prominent in the lung epithelium during glandular development. It declines at the end of the canalicular phase. We further compare the Irx1 and Irx2 expression domains to Gli1, 2, 3 and Mash1. Their homologues in Drosophila melanogaster are known as regulative partners of the iroquois complex. The Irx and Gli genes are coexpressed in the developing lungs at the same time. Their transcripts are not localised in the same cells but adjacent to each other in either mesenchymal or epithelial structures. It is thought that the lung development is regulated by the mesenchymal/epithelial interactions.
Assuntos
Expressão Gênica , Proteínas de Homeodomínio/genética , Pulmão/embriologia , Proteínas do Tecido Nervoso , Proteínas Repressoras , Fatores de Transcrição/genética , Proteínas de Xenopus , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Proteínas de Ligação a DNA/genética , Epitélio/embriologia , Epitélio/metabolismo , Perfilação da Expressão Gênica , Genes Homeobox , Proteínas de Homeodomínio/metabolismo , Hibridização In Situ , Fatores de Transcrição Kruppel-Like , Pulmão/metabolismo , Mesoderma/metabolismo , Camundongos , Proteínas Oncogênicas/genética , Transativadores , Fatores de Transcrição/metabolismo , Proteína GLI1 em Dedos de Zinco , Proteína Gli2 com Dedos de Zinco , Proteína Gli3 com Dedos de ZincoRESUMO
Irx1 and Irx2 are members of the murine Iroquois homeobox (Irx) gene family. In this study, we describe the dynamic expression pattern of these genes during limb development with a focus on digit formation. We further present a comparative expression analysis with Gli genes (Gli1, Gli2, Gli3). Gli1, Gli2, and Gli3 were suggested for candidate regulators of the Irx genes. The expression was studied between E11.5 and E14.5 when the digits are being formed. Irx1 and Irx2 reproduce the developmental program of the digits in time and space and the Irx1 provides an early and excellent marker for this process. Our analysis also indicates that the expression of Irx1, Gli1 and Irx2, Gli2 are relative to each other. In contrast, Gli3 exhibits a different expression pattern.
Assuntos
Expressão Gênica , Proteínas de Homeodomínio/genética , Proteínas do Tecido Nervoso , Proteínas Repressoras , Dedos do Pé/embriologia , Fatores de Transcrição/genética , Proteínas de Xenopus , Animais , Proteínas de Ligação a DNA/genética , Membro Anterior/embriologia , Membro Anterior/metabolismo , Perfilação da Expressão Gênica , Genes Homeobox , Membro Posterior/embriologia , Membro Posterior/metabolismo , Fatores de Transcrição Kruppel-Like , Camundongos , Proteínas Oncogênicas/genética , Transativadores , Proteína GLI1 em Dedos de Zinco , Proteína Gli2 com Dedos de Zinco , Proteína Gli3 com Dedos de ZincoRESUMO
In Drosophila the decision processes between the neural and epidermal fate for equipotent ectodermal cells depend on the activity of proneural genes. Members of the Drosophila Iroquois-Complex (Iro-C) positively regulate the activity of certain proneural AS-C genes during the formation of external sensory organs. We have identified and characterized three mouse Iroquois-related genes: Irx1, -2 and -3, which have a homeodomain very similar to that of the Drosophila Iro-C genes. The sequence similarity implies that these three genes represent a separate homeobox family. All three genes are expressed with distinct spatio/temporal patterns during early mouse embryogenesis. These patterns implicate them in a number of embryonic developmental processes: the A/P and D/V patterning of specific regions of the central nervous system (CNS), and regionalization of the otic vesicle, branchial epithelium and limbs.
