Transposon-mediated rewiring of gene regulatory networks contributed to the evolution of pregnancy in mammals.

A fundamental challenge in biology is explaining the origin of novel phenotypic characters such as new cell types; the molecular mechanisms that give rise to novelties are unclear. We explored the gene regulatory landscape of mammalian endometrial cells using comparative RNA-Seq and found that 1,532 genes were recruited into endometrial expression in placental mammals, indicating that the evolution of pregnancy was associated with a large-scale rewiring of the gene regulatory network. About 13% of recruited genes are within 200 kb of a Eutherian-specific transposable element (MER20).

Survival of the sparsest: robust gene networks are parsimonious.

Biological gene networks appear to be dynamically robust to mutation, stochasticity, and changes in the environment and also appear to be sparsely connected. Studies with computational models, however, have suggested that denser gene networks evolve to be more dynamically robust than sparser networks. We resolve this discrepancy by showing that misassumptions about how to measure robustness in artificial networks have inadvertently discounted the costs of network complexity.

Promotion of safe sex: evaluation of a community-level intervention programme in gay bars, saunas and sex shops.

This study was an evaluation of a safe sex promotion programme in gay bars, saunas and sex shops in Québec City. The impact of the intervention on safe sex was assessed by means of an interrupted sequential pre-interventions and post-interventions quasi-experimental design with independent samples. At each measurement time, approximately 320 individuals were recruited in gay bars and saunas and were invited to complete a self-administered questionnaire.