This week in PLOS Biology

In PLOS Biology this week, you can read about tracking the evolution of cancer, sexual dimorphism, parasite tolerance in wild mammals and negative feedback mechanisms in cortical neurons.

A new Community Page by Miriam Jamal-Hanjani, Charles Swanton and colleagues highlights TRACERx, a prospective study of patients with primary non-small cell lung cancer. The idea is to follow cancer cases from diagnosis to relapse and conduct tumour sampling and genetic analysis. When paired with data on therapeutic interventions, the resulting information on the evolution of real tumours could help identify novel therapeutic targets.

Anisogamy – the phenomenon of the gametes of each mating type differing in form (e.g. small, mobile sperm and large, stationary eggs) – is common across the tree of life. A study by Sa Geng, Peter DeHoff and James Umen investigated sex determination in the multicellular green alga Volvox carteri. They found that a protein that controlled identical-looking mating types in an ancestral unicellular alga evolved to control the development of visibly different sexes in its multicellular descendant Volvox. This study seems to show that sexual dimorphism can arise from isogamy (sexual reproduction where gametes are of similar shape and size) largely via changes in the sex-determining gene itself.

When faced with a parasite infection, the two options for animals are resistance (expelling the parasites) and tolerance (mitigating the damage caused by the parasites). New research by Joseph Jackson, Mike Begon and colleagues used field voles to investigate the switch between these two strategies. As the voles matured, they moved from resistance to tolerance of parasite infection. They identified the transcription factor Gata3 as an important marker of the shift to tolerance over time.

In order for cortical neurons (brain cells responsible for memory) to work properly, the ratio of excitation and inhibition (E/I) has to remain constant. However, this locked relationship can constrain neuronal plasticity and learning. New research by Joana Lourenço, Alberto Bacci and colleagues finds that activation of cortical pyramidal neurons mobilizes nitric oxide, which then enhances release of the neurotransmitter GABA from nearby inhibitory interneurons, thereby transiently freeing specific pyramidal neurons from the tyranny of a fixed E/I.