DNA rearrangements and variation in Bordetella pertussis

Vir- (avirulent) strains of B, pertussis were selected, via increased resistance to erythromycin, which were isogenic with parental Vir+ strains. Chromosomal DNA from these pairs of strains were studied with a number of probes and with methylation-sensitive restriction endonucleases. These experiments suggested that DNA rearrangements were not involved in the Vir+ to Vir switch, and that the methylation status of the DNA was not altered during the switch. A B, pertussis gene library was probed with an oligonucleotide specific for the fimbrial subunit genes. This probe revealed that the chromosome of B. pertussis strain Taberman contained three fimbrial subunit genes:- i) an active fim 3 gene, ii) an inactive fim 2 gene, and iii) a gene dissimilar from the previously characterised fim X gene. The behaviour of the fim 3 gene in various AGG 3-strains was investigated, and these studies revealed that a cis-acting factor was responsible for inactivation of the chromosomal fim 3 gene in these strains. It was also shown that the fim 3 locus encoded fimbrial structures when conjugated into an afimbrial B. pertussis strain. No evidence was found to suggest that DNA rearrangements were Involved in serotype variation. A probe made from the hin gene, which controls the invertible region of Salmonella typhimurium, was found to hybridise to chromosomal DNA from B, pertussis, under reduced stringency conditions. The gene library was probed with this probe and a cosmid clone Isolated, This clone did not appear to produce an active invertase in E. coli, when tested in two different inversion assays. An oligonucleotide probe was produced which was homologous with the recombination sites recognised by the hin-like family of invertase proteins and this also hybridised to B. pertussis chromosomal DNA under reduced stringency conditions

Mental Ill Health, Recovery and the Family Assemblage

The recovery approach is now among the most influential paradigms shaping mental health policy and practice across the English-speaking world. While recovery is normally presented as a deeply personal process, critics have challenged the individualism underpinning this view. A growing literature on “family recovery” explores the ways in which people, especially parents with mental ill health, can find it impossible to separate their own recovery experiences from the processes of family life. While sympathetic to this literature, we argue that it remains limited by its anthropocentricity, and therefore struggles to account for the varied human and nonhuman entities and forces involved in the creation and maintenance of family life. The current analysis is based on an ethnographic study conducted in Australia, which focused on families in which the father experiences mental ill health. We employ the emerging concept of the “family assemblage” to explore how the material, social, discursive and affective components of family life enabled and impeded these fathers’ recovery trajectories. Viewing families as heterogeneous assemblages allows for novel insights into some of the most basic aspects of recovery, challenging existing conceptions of the roles and significance of emotion, identity and agency in the family recovery process