A long-term evolution experiment with Escherichia coli shows that the appearance and optimization of a new trait can require both co-opting existing cellular pathways for new roles and reversing a history of previous adaptation.
Analysis of embryonic mouse diaphragm reveals muscle and nerve left–right asymmetries set by a Nodal-dependent genetic cascade, which imprints different molecular signatures to left and right motoneurons that shape their innervation pattern.
Molecular labeling, electrophysiology and calcium imaging have revealed a novel switching of neurotransmitter at the frog neuromuscular junction where motoneurons transiently release glutamate before acetylcholine at synapses on developing hindlimb muscles at the onset of metamorphosis.
Plexin controls the spatial distribution of synapses by locally inhibiting Rap2 small GTPase activity along the axon, and a Rap2 effector, TNIK, which also plays a key role in inhibiting synapse number.
The foundations of genomic complexity in multicellular animals have deep roots in their unicellular prehistory, both in terms of innovations in gene content, as well as the evolutionary dynamics of genome architecture.