In this work we have characterized the effects of the intercalator ethidium bromide (EtBr) on the DNA condensation process by using force spectroscopy and gel electrophoresis. We have tested two condensing agents: spermine (spm(4+)), a tetravalent cationic amine which promotes cation-induced DNA condensation, and poly(ethylene glycol) (PEG), a neutral polymer which promotes DNA ψ-condensation. Two different types of experiments were performed. In the first type, bare DNA molecules disperse in solution are first treated with EtBr for intercalation, and then the condensing agent is added to the sample with the purpose of verifying the effects of the intercalator in hindering DNA condensation. In the second experiment type, the bare DNA molecules are first condensed, and then the intercalator is added to the sample in order to verify its influence on the previously condensed DNA. The results obtained with the two different experimental techniques used agree very well, indicating that previously intercalated EtBr can hinder both cation-induced and ψ-condensation, being more efficient in the first case. On the other hand, EtBr has little effect on the previously formed cation-induced condensates, but is efficient in unfolding the ψ-condensates.

Neste artigo, abordamos os termos da representação lésbica em dois longas-metragens, de ficção, realizados por mulheres no Brasil, no período de ditadura civil-militar (1964-1985). Analisamos Marcados para viver (1976), de Maria do Rosário Nascimento e Silva, e Amor maldito (1984), de Adélia Sampaio.  Partimos de referenciais feministas do cinema, que reconhecem o jogo de (in)visibilidade lésbica em cinematografias, desde filmes clássicos de Hollywood, sustentando que, apesar de códigos de censura e do padrão de heterossexualidade compulsória ou de heteronormatividade, as lésbicas sempre apareceram neles, mesmo que de maneira fantasmagórica. ====== In this article, I address the terms of lesbian representation in two fictional feature films directed by women in Brazil during the period of civil-military dictatorship (1964-1985), namely Marcados para viver (1976), by Maria do Rosário Nascimento e Silva, and Amor maldito (1984), by Adélia Sampaio. Beginning with feminist references in cinema, which have recognized the play of lesbian (in)visibility in cinematographies since the classic age of Hollywood, I maintain that, despite censorship codes and the standard of compulsory heterosexuality or heteronormativity, lesbians have always been present, even if in a ghostly manner.

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A crise política brasileira recente coloca em quadro a hipótese do caráter inconcluso da última transição democrática do país (anos 1980). Este artigo aborda o documentário The Brazilian Connection: a struggle for democracy, de Helena Solberg, de 1982, para esquadrinhar as principais tensões do período em questão, registradas em imagens e nos depoimentos desse emblemático filme da transição política no país. Parte-se da relevância das imagens na contemporaneidade, inserindo o texto nos estudos de História e audiovisual.