RESUMO
The orf162b sequence, the second open reading frame 3' of the reaction center (RC) H protein gene puhA in the Rhodobacter capsulatus photosynthesis gene cluster, is shown to be transcribed from a promoter located 5' of puhA. A nonpolar mutation of orf162b was generated by replacing most of the coding region with an antibiotic resistance cartridge. Although the mutant strain initiated rapid photosynthetic growth, growth slowed progressively and cultures often entered a pseudostationary phase. The amounts of the RC and light harvesting complex I (LHI) in cells obtained from such photosynthetic cultures were abnormally low, but these deficiencies were less severe when the mutant was grown to a pseudostationary phase induced by low aeration in the absence of illumination. The orf162b mutation did not significantly affect the expression of a pufB::lacZ translationally in-frame gene fusion under the control of the puf promoter, indicating normal transcription and translation of RC and LHI genes. Spontaneous secondary mutations in the strain with the orf162b disruption resulted in a bypass of the photosynthetic growth retardation and reduced the level of light harvesting complex II. These results and the presence of sequences similar to orf162b in other species indicate that the Orf162b protein is required for normal levels of the photosynthetic apparatus in purple photosynthetic bacteria.
Assuntos
Genes Bacterianos , Complexos de Proteínas Captadores de Luz , Fases de Leitura Aberta , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Rhodobacter capsulatus/metabolismo , Fusão Gênica Artificial , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Eletroforese em Gel de Poliacrilamida/métodos , Expressão Gênica , Espectrometria de Massas , Mutagênese , Óperon , Fenótipo , Fotossíntese , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Rhodobacter capsulatus/genética , Rhodobacter capsulatus/crescimento & desenvolvimento , Dodecilsulfato de Sódio , Transcrição GênicaRESUMO
OBJECTIVE: This study was conducted with mothers recovering from drug and alcohol addiction and had three aims: first, to understand the range of negative childhood events these mothers experienced; second, to understand their current level of distress and their parenting experiences; and third, to examine the relationships between negative childhood events and parenting experiences. METHOD: Forty-six mothers participated in a cross-sectional exploratory study and completed a range of self-report measures, including the Child Abuse & Trauma Scale, Social Support Inventory, CES-D, Parenting Stress Index, and the Parenting Scale. RESULTS: When compared to norming samples these mothers reported significantly higher levels of aversive childhood experiences, psychological distress, parenting stress and use of problematic parenting behaviors along with lower levels of social support. Higher levels of neglect and growing up in a negative home environment were significantly correlated with lower levels of social support from the family, higher levels of distress and parenting stress, and greater use of problematic parenting behaviors. CONCLUSION: For this sample there is a greater incidence of aversive childhood experiences and greater problems with maternal functioning. Mothers recovering from addiction have an additional need for clinical attention towards issues of recovery from childhood abuse and responding to parenting difficulties with their own children.