Development

Timing of CNS cell generation: a programmed sequence of neuron and glial cell production from isolated murine cortical stem cells. Qian, X. et al. Neuron 28 , 69–80 (2000)

The first lineage analysis of a vertebrate neural stem cell. Qian et al. studied individual cortical stem cells in culture and determined the fate of their descendants using long-term video microscopy. They observed that neurogenesis preceded gliogenesis. Initially, stem cells divide asymmetrically and produce a neuroblast and another stem cell. Later, the stem cells lose the potential to produce neuroblasts and enter into a proliferative state able to generate glia. [ Pubmed]

Synaptic plasticity

Learning-induced LTP in neocortex. Rioult-Pedotti, M. -S. et al. Science 290 , 533–536 (2000)

Previous attempts to interfere with learning by saturating synaptic efficacy have not yielded conclusive results. Rioult-Pedotti et al. used the converse strategy and found that motor learning interferes with subsequent induction of long-term potentiation (LTP) in the motor cortex, consistent with the idea that LTP is involved in learning. In addition, they observed that training does not shift the upper limit of LTP magnitude, indicating that synapses may normally operate within a constant range of efficacy. [ Pubmed]

Ion channels

Mechanisms for activation and antagonism of an AMPA-sensitive glutamate receptor: crystal structures of the GluR2 ligand binding core.  Armstrong, N. & Gouaux, E. Neuron 28 , 165–181 (2000)

The authors solved the crystal structure of the GluR2 ligand-binding core in the free state and in the presence of various ligands. The binding of a full agonist induced a larger degree of domain closure than a partial agoinst. An antagonist, in turn, caused minimal closure of the core. These findings indicate that the level of channel activation may depend directly on the extent of domain closure. In addition, the binding domain packed as a dimer in the crystals, indicating that GluR2 may assemble as a dimer of dimers. [ Pubmed]

Development

Pax6 activity in the lens primordium is required for lens formation and for the correct placement of a single retina in the eye. Ashery-Padan, R. et al. Genes Dev. 14 , 2701–2711 (2000)

The transcription factor Pax6 is crucial for eye formation. To dissociate the role of this factor on the development of the different eye components, the authors generated mice lacking Pax6 exclusively in the lens surface ectoderm. Although lens induction occurred in these mice, its further development was arrested. Notably, the absence of lens led to the formation of several independent retinas, pointing to a direct role of the lens in controlling retinal development. [ Pubmed]