Retrotransposons and the evolution of mammalian gene expression

Transposable elements, and retroviral-like elements in particular, are a rich potential source of genetic variation within a host's genome. Many mutations of endogenous genes in phylogenetically diverse organisms are due to insertion of elements that affect gene expression by altering the normal pattern of regulation. While few such associations are known to have been maintained over time, two recently elucidated examples suggest transposable elements may have a significant impact in evolution of gene expression. The first example, concerning the mouse sex-limited protein ( Slp ), clearly establishes that ancient retroviral enhancer sequences now confer hormonal dependence on the adjacent gene. The second example shows that within the human amylase gene family, salivary specific expression has arisen due to inserted sequences, deriving perhaps from a conjunction of two retrotransposable elements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42800/1/10709_2004_Article_BF00133720.pd

Aromatic Cation Activation: Nucleophilic Substitution of Alcohols and Carboxylic Acids

A new method for the nucleophilic substitution of alcohols and carboxylic acids using aromatic tropyliumcation activation has been developed. This article reports the use of chloro tropylium chloride for the rapid generation of alkyl halides and acyl chlorides under very mild reaction conditions. It demonstrates, for the first time, the synthetic potential of tropylium cations in promoting chemical transformations

Desempenho e qualidade dos ovos de poedeiras comerciais alimentadas com rações contendo farelo de coco tratado ou não com antioxidante Performance and egg quality of laying hens fed diets containing coconut meal treated with and without antioxidant

Este experimento foi conduzido para avaliar a estabilidade oxidativa do farelo de coco (FC) tratado ou não com butil-hidroxitolueno (BHT) e armazenado por 35 dias e estudar o efeito de rações contendo esse ingrediente sobre o desempenho e a qualidade do ovo de poedeiras. Um lote de 200 kg de farelo de coco foi dividido em cinco partes: uma foi armazenada sem a adição de antioxidante e as demais tratadas com 500 ppm de BHT nos dias 0, 7, 14 e 21. A estabilidade oxidativa do farelo de coco foi acompanhada por meio dos índices de acidez e de peróxidos, determinados semanalmente. Após 35 dias de armazenamento, 10% de farelo de coco tratado e não tratado com BHT nos diferentes tempos de armazenamento foi usado na formulação de rações isonutrientes para poedeiras comerciais. Foram utilizadas 180 poedeiras da linhagem Hisex White, distribuídas ao acaso em 5 tratamentos e 6 repetições de 6 aves cada. Os índices de acidez e de peróxidos do farelo de coco armazenado com ou sem BHT aumentaram com o tempo de armazenamento. Contudo, os tratamentos não afetaram o desempenho nem a qualidade dos ovos das aves. O farelo de coco armazenado por 35 dias sem antioxidante, embora sofra oxidação, pode ser usado em níveis de até 10% na ração para poedeiras comerciais.<br>This experiment was conducted to evaluate the oxidative stability of coconut meal treated with or without butylated hydroxytoluene (BHT) at different storage times and the effect of diets containing this ingredient on laying hens' performance and egg quality. A 200-kg batch of freshly produced coconut meal was divided into five equal portions. One portion was stored without BHT and the others were treated with BHT at zero, 7, 14 and 21 days. The oxidative stability of coconut meal was measured by the acidity index and peroxide index determined weekly. At the end of the 35-day storage time, this ingredient was used in the formulation of diets for laying hen. One hundred and eighty Hisex White laying hens were randomly distributed among five treatments with six repetitions of six birds each. The acidity index and peroxide index of coconut meal treated with or without BHT at different periods of time increased with storage time. Nevertheless, treatments did not affect laying hens' performance or egg quality. Coconut meal stored for 35 days, although showing lipid peroxidation, can be included at 10% level in the diet for commercial poultry