Decorative white silk crosses are an ingenious tactic used by orb-weaving spiders to protect their webs from damage. Decorative white silk crosses are an ingenious tactic used by orb-weaving spiders to protect their webs from damage, a new study from the University of Melbourne has revealed.

This is a nude mouse with a grafted human prostate tumor (indicated by white bump near shoulder blade). XMRV arose from recombination event in this breed of mouse.
Delineation of the origin of the retrovirus known as XMRV from the genomes of laboratory mice indicates that the virus is unlikely to be responsible for either prostate cancer or chronic fatigue syndrome in humans, as has been widely published. The virus arose because of genetic recombination of two mouse viruses. Subsequent infection of lab experiments with XMRV formed the basis of the original association.