Home About us Contact
|
Home About us Contact | ||
|
|
||
Secondary Consequence (secondary + consequence)
Selected AbstractsEnvironmental tuning of mutation ratesENVIRONMENTAL MICROBIOLOGY, Issue 2 2006Claude Saint-Ruf Summary Through their life cycles, bacteria experience many different environments in which the relationship between available energy resources and the frequency and the nature of various stresses is highly variable. In order to survive in such changeable environments, bacteria must balance the need for nutritional competence with stress resistance. In Escherichia coli natural populations, this is most frequently achieved by changing the regulation of the RpoS sigma factor-dependent general stress response. One important secondary consequence of altered regulation of the RpoS regulon is the modification of mutation rates. For example, under nutrient limitation during stationary phase, the high intracellular concentration of RpoS diminishes nutritional competence, increases stress resistance, and, by downregulating the mismatch repair system and downregulating the expression of the dinB gene (coding for PolIV translesion synthesis polymerase) increases mutation rates. The reduction of the intracellular concentration of RpoS has exactly opposite effects on nutritional competence, stress resistance and mutation rates. Therefore, the natural selection that favours variants having the highest fitness under different environmental conditions results in high variability of stress-associated mutation rates in those variants. [source] Biological roles of translesion synthesis DNA polymerases in eubacteriaMOLECULAR MICROBIOLOGY, Issue 3 2010Dan I. Andersson Summary Biological systems are strongly selected to maintain the integrity of their genomes by prevention and repair of external and internal DNA damages. However, some types of DNA lesions persist and might block the replication apparatus. The universal existence of specialized translesion synthesis DNA polymerases (TLS polymerases) that can bypass such lesions in DNA implies that replication blockage is a general biological problem. We suggest that the primary function for which translesion synthesis polymerases are selected is to rescue cells from replication arrest at lesions in DNA, a situation that, if not amended, is likely to cause an immediate and severe reduction in cell fitness and survival. We will argue that the mutagenesis observed during translesion synthesis is an unavoidable secondary consequence of this primary function and not, as has been suggested, an evolved mechanism to increase mutation rates in response to various stresses. Finally, we will discuss recent data on additional roles for translesion synthesis polymerases in the formation of spontaneous deletions and in transcription-coupled TLS, where the coupling of transcription to TLS is proposed to allow the rescue of the transcription machinery arrested at DNA lesions. [source] Spectropolarimetry of a complete infrared-selected sample of Seyfert 2 galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001S.L. Lumsden We report the results of a spectropolarimetric survey of a complete far-infrared-selected sample of Seyfert 2 galaxies. We have found polarized broad H, emission in one new source, NGC 5995. In the sample as a whole, there is a clear tendency for galaxies in which we have detected broad H, in polarized light to have warm mid,far-infrared colours in agreement with our previous results. However, a comparison of the optical, radio and hard X-ray properties of these systems leads us to conclude that this is a secondary consequence of the true mechanism governing our ability to see scattered light from the broad-line region. We find a strong trend for galaxies showing such emission to lie above a critical value of the relative luminosity of the active core to the host galaxy (as measured from the [O iii] 5007-Ĺ equivalent width) which varies as a function of the obscuring column density as measured from hard X-ray observations. The warmth of the infrared colours is then largely due to a combination of the luminosity of the active core, the obscuring column and the relative importance of the host galaxy in powering the far-infrared emission, and not solely orientation as we inferred in our previous paper. Our data may also provide an explanation as to why the most highly polarized galaxies, which appear to have tori that are largely edge-on, are also the most luminous and have the most easily detectable scattered broad H,. [source] Genetic and environmental influences on the transmission of parental depression to children's depression and conduct disturbance: an extended Children of Twins studyTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 6 2010Judy L. Silberg Background:, Despite the increased risk of depression and conduct problems in children of depressed parents, the mechanism by which parental depression affects their children's behavioral and emotional functioning is not well understood. The present study was undertaken to determine whether parental depression represents a genuine environmental risk factor in children's psychopathology, or whether children's depression/conduct can be explained as a secondary consequence of the genetic liability transmitted from parents to their offspring. Methods:, Children of Twins (COT) data collected on 2,674 adult female and male twins, their spouses, and 2,940 of their children were used to address whether genetic and/or family environmental factors best account for the association between depression in parents and depression and conduct problems in their children. Data collected on juvenile twins from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) were also included to estimate child-specific genetic and environmental influences apart from those effects arising from the transmission of the parental depression itself. The fit of alternative Children of Twin models were evaluated using the statistical program Mx. Results:, The most compelling model for the association between parental and juvenile depression was a model of direct environmental risk. Both family environmental and genetic factors accounted for the association between parental depression and child conduct disturbance. Conclusions:, These findings illustrate how a genetically mediated behavior such as parental depression can have both an environmental and genetic impact on children's behavior. We find developmentally specific genetic factors underlying risk to juvenile and adult depression. A shared genetic liability influences both parental depression and juvenile conduct disturbance, implicating child conduct disturbance (CD) as an early indicator of genetic risk for depression in adulthood. In summary, our analyses demonstrate differences in the impact of parental depression on different forms of child psychopathology, and at various stages of development. [source] Do studies in caveolin-knockouts teach us about physiology and pharmacology or instead, the ways mice compensate for ,lost proteins'?BRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2007P A Insel A wide array of phenotypic changes have been reported in mice with knockout of expression of caveolin-1. Neidhold et al. (2007) describe results in this issue that continue this trend by showing that saphenous arteries from adult caveolin-1 knockout mice lack caveolae, lose ,1 -adrenoceptor-promoted relaxation, gain ,3 -adrenoceptor-promoted relaxation but show no change in vasomotor response to ,2 -adrenoceptor activation. Neither the physiological importance for wild-type animals nor the mechanistic basis for these changes is clear. Although the caveolin-1 knockout and wild-type mice express similar levels of the receptor mRNAs, the protein expression of the receptors is not specified and represents, in our view, an important limitation of the study. We also question the physiological relevance of the findings and ask: Do studies in total body/lifespan caveolin-knockout mice further understanding of physiology and pharmacology or do they primarily characterize secondary consequences? We propose that alternative approaches that decrease caveolin expression in a temporally and spatially discrete manner are more likely to facilitate definitive conclusions regarding caveolin-1 and its role in regulation of , -adrenoceptors and other pharmacological targets. British Journal of Pharmacology (2007) 150, 251,254. doi:10.1038/sj.bjp.0706981 [source] Obsessional beliefs, compulsive behaviours and symptom severity: their evolution and interrelation over stages of treatmentCLINICAL PSYCHOLOGY AND PSYCHOTHERAPY (AN INTERNATIONAL JOURNAL OF THEORY & PRACTICE), Issue 1 2008Sébastien Grenier The current study reports a case series examining (1) the variation in strength of obsessional doubt and belief in consequences of the doubt; and (2) the interaction between these cognitive components and symptom measures of duration and severity of obsessive,compulsive disorder (OCD), over 24 weeks of cognitive behaviour therapy. Eight participants diagnosed with OCD, four with contamination-related rituals and four with checking behaviours, were selected on the basis of the Yale,Brown obsessive,compulsive scale (Y-BOCS) and Padua ratings. All participants completed daily diaries measuring strength of principal obsessional doubt (0,100), strength of belief in consequences of the doubt (0,100) and the duration of the compulsive rituals throughout the 24 weeks of therapy. Severity of symptomatology was measured pre- and post-treatment using the Y-BOCS. Change in all measures was analysed over time following the procedure outlined by Storchheim and O'Mahoney (2006). Results showed that decrease in belief in secondary consequences is always accompanied by a decrease in strength of obsessions, but the converse does not hold. Furthermore, change in OCD symptomatology may precede cognitive changes. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||