Sexual conflict maintains variation at an insecticide resistance locus

Background: The maintenance of genetic variation through sexually antagonistic selection is controversial, partly because specific sexually-antagonistic alleles have not been identified. The Drosophila DDT resistance allele (DDT-R) is an exception. This allele increases female fitness, but simultaneously decreases male fitness, and it has been suggested that this sexual antagonism could explain why polymorphism was maintained at the locus prior to DDT use. We tested this possibility using a genetic model and then used evolving fly populations to test model predictions. Results: Theory predicted that sexual antagonism is able to maintain genetic variation at this locus, hence explaining why DDT-R did not fix prior to DDT use despite increasing female fitness, and experimentally evolving fly populations verified theoretical predictions. Conclusions: This demonstrates that sexually antagonistic selection can maintain genetic variation and explains the DDT-R frequencies observed in nature

How do we safely treat depression in children, adolescents and young adults?

Increasing concerns about the safety and efficacy of antidepressant drugs for children, adolescents and young adults have been countered by claims that reduced prescribing of antidepressants may have dangerous consequences. This leaves clinicians unsure as to how to weigh up the evidence and apply it to their patients. This paper promotes an approach of evaluating the evidence in each study according to the importance of the outcomes being measured in that study. It finds that on important measures such as mortality, hospitalization and quality of life, the evidence is unfavourable for antidepressants in this population. Here, an approach is suggested that primary care physicians might adopt with their depressed young patients. Through a combination of 'watchful waiting' and physical and emotional rehabilitation, physicians can actively intervene without reliance on medication or psychotherapy.Jon Jureidin