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Connect the Nerves

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New findings suggest that a subpopulation of glia—the brain's filler material—act as the all-important neuronal precursors... Even more startling, a widespread glial cell type called the astrocyte can be converted into a neuronal precursor by the expression of a single gene. “These astrocytes are not viewed anymore as a specialized cell type but rather as a precursor cell,” said Magdalena Götz (Max-Planck Institute, Göttingen, Germany). “And once we think we have precursors everywhere, we can think how to manipulate these precursors. ” Precursor activity is most obvious in the developing brain... In the neocortex, for example, it was thought that newly born neurons migrated up the long processes of radial glial cells... But now they have achieved the same rescue by adding just 0.1 pg of oxytocin to a brain region called the medial amygdala... A similar addition to the olfactory bulb had no such effect... For at least some types of memories, an active retention process must take place during retrieval, or else the original memory will be lost... Now researchers have found that the machinery driving the original memory acquisition and the later memory retention shares some, but not all, components... Now the race is on to decipher the logic underlying these differences. ▪ Reference: If axons are to turn on a dime, then translation would not be the first suspect as a way of regulating direction-finding... But, in results that she said came as “a complete surprise,” Douglas Campbell and Christine Holt of Cambridge University (Cambridge, UK) have found that common axon guidance molecules work by turning on translation at the tip of the growing neurite... Axons of retinal ganglion cells (RGCs) start off by slithering along the laminin coating of the retina, before a roadway of netrin induces a turn into the brain... Ephrin at the midline controls how many neurons cross into the other side of the brain, and then semaphorin 3A bumps the neurons onto a course headed for the optic tectum... This is where the translation switch comes in... The hardware needed for such a switch is certainly present in the axon—ribosomes were localized to axons decades ago. “But that old literature seems to have been forgotten,” said Holt.In 2000, Mark Bear (Brown University, Providence, RI) found that rapid induction of local translation was important in changing the activities of dendrites... Within five minutes of attractant or repellent addition, 4E and its binding protein are phosphorylated... Holt does not yet know if this change is sufficient to induce guidance, nor does she know which target mRNAs are critical to changing the behavior of the axon.

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Semaphorin (blue) helps retinal neurons turn (right) and branch (top left).Holt/SFN
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uro2: Semaphorin (blue) helps retinal neurons turn (right) and branch (top left).Holt/SFN


Connect the Nerves
Semaphorin (blue) helps retinal neurons turn (right) and branch (top left).Holt/SFN
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199347&req=5

uro2: Semaphorin (blue) helps retinal neurons turn (right) and branch (top left).Holt/SFN

View Article: PubMed Central

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

New findings suggest that a subpopulation of glia—the brain's filler material—act as the all-important neuronal precursors... Even more startling, a widespread glial cell type called the astrocyte can be converted into a neuronal precursor by the expression of a single gene. “These astrocytes are not viewed anymore as a specialized cell type but rather as a precursor cell,” said Magdalena Götz (Max-Planck Institute, Göttingen, Germany). “And once we think we have precursors everywhere, we can think how to manipulate these precursors. ” Precursor activity is most obvious in the developing brain... In the neocortex, for example, it was thought that newly born neurons migrated up the long processes of radial glial cells... But now they have achieved the same rescue by adding just 0.1 pg of oxytocin to a brain region called the medial amygdala... A similar addition to the olfactory bulb had no such effect... For at least some types of memories, an active retention process must take place during retrieval, or else the original memory will be lost... Now researchers have found that the machinery driving the original memory acquisition and the later memory retention shares some, but not all, components... Now the race is on to decipher the logic underlying these differences. ▪ Reference: If axons are to turn on a dime, then translation would not be the first suspect as a way of regulating direction-finding... But, in results that she said came as “a complete surprise,” Douglas Campbell and Christine Holt of Cambridge University (Cambridge, UK) have found that common axon guidance molecules work by turning on translation at the tip of the growing neurite... Axons of retinal ganglion cells (RGCs) start off by slithering along the laminin coating of the retina, before a roadway of netrin induces a turn into the brain... Ephrin at the midline controls how many neurons cross into the other side of the brain, and then semaphorin 3A bumps the neurons onto a course headed for the optic tectum... This is where the translation switch comes in... The hardware needed for such a switch is certainly present in the axon—ribosomes were localized to axons decades ago. “But that old literature seems to have been forgotten,” said Holt.In 2000, Mark Bear (Brown University, Providence, RI) found that rapid induction of local translation was important in changing the activities of dendrites... Within five minutes of attractant or repellent addition, 4E and its binding protein are phosphorylated... Holt does not yet know if this change is sufficient to induce guidance, nor does she know which target mRNAs are critical to changing the behavior of the axon.

No MeSH data available.