BACKGROUND: Nervous systems are largely bilaterally symmetric on a morphological level but often display striking degrees of functional left/right (L/R) asymmetry. How L/R asymmetric functional features are superimposed onto an essentially bilaterally symmetric structure and how nervous-system laterality relates to the L/R asymmetry of internal organs are poorly understood. We address these questions here by using the establishment of L/R asymmetry in the ASE chemosensory neurons of C. elegans as a paradigm. This bilaterally symmetric neuron pair is functionally lateralized in that it senses a distinct class of chemosensory cues and expresses a putative chemoreceptor family in a L/R asymmetric manner. RESULTS: We show that the directionality of the asymmetry of the two postmitotic ASE neurons ASE left (ASEL) and ASE right (ASER) in adults is dependent on a L-/R-symmetry-breaking event at a very early embryonic stage, the six-cell stage, which also establishes the L/R asymmetric placement of internal organs. However, the L/R asymmetry of the ASE neurons per se is dependent on an even earlier anterior-posterior (A/P) Notch signal that specifies embryonic ABa/ABp blastomere identities at the four-cell stage. This Notch signal, which functions through two T box genes, acts genetically upstream of a miRNA-controlled bistable feedback loop that regulates the L/R asymmetric gene-expression program in the postmitotic ASE cells. CONCLUSIONS: Our results link adult neuronal laterality to the generation of the A/P axis at the two-cell stage and raise the possibility that neural asymmetries observed across the animal kingdom are similarly established by very early embryonic interactions.
%0 Journal Article
%1 Poole:2006:Curr-Biol:17141609
%A Poole, R J
%A Hobert, O
%D 2006
%J Curr Biol
%K "c asymmetry elegans" left notch right
%N 23
%P 2279-2292
%R 10.1016/j.cub.2006.09.041
%T Early embryonic programming of neuronal left/right asymmetry in C. elegans
%U http://www.ncbi.nlm.nih.gov/pubmed/17141609?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum
%V 16
%X BACKGROUND: Nervous systems are largely bilaterally symmetric on a morphological level but often display striking degrees of functional left/right (L/R) asymmetry. How L/R asymmetric functional features are superimposed onto an essentially bilaterally symmetric structure and how nervous-system laterality relates to the L/R asymmetry of internal organs are poorly understood. We address these questions here by using the establishment of L/R asymmetry in the ASE chemosensory neurons of C. elegans as a paradigm. This bilaterally symmetric neuron pair is functionally lateralized in that it senses a distinct class of chemosensory cues and expresses a putative chemoreceptor family in a L/R asymmetric manner. RESULTS: We show that the directionality of the asymmetry of the two postmitotic ASE neurons ASE left (ASEL) and ASE right (ASER) in adults is dependent on a L-/R-symmetry-breaking event at a very early embryonic stage, the six-cell stage, which also establishes the L/R asymmetric placement of internal organs. However, the L/R asymmetry of the ASE neurons per se is dependent on an even earlier anterior-posterior (A/P) Notch signal that specifies embryonic ABa/ABp blastomere identities at the four-cell stage. This Notch signal, which functions through two T box genes, acts genetically upstream of a miRNA-controlled bistable feedback loop that regulates the L/R asymmetric gene-expression program in the postmitotic ASE cells. CONCLUSIONS: Our results link adult neuronal laterality to the generation of the A/P axis at the two-cell stage and raise the possibility that neural asymmetries observed across the animal kingdom are similarly established by very early embryonic interactions.
@article{Poole:2006:Curr-Biol:17141609,
abstract = {BACKGROUND: Nervous systems are largely bilaterally symmetric on a morphological level but often display striking degrees of functional left/right (L/R) asymmetry. How L/R asymmetric functional features are superimposed onto an essentially bilaterally symmetric structure and how nervous-system laterality relates to the L/R asymmetry of internal organs are poorly understood. We address these questions here by using the establishment of L/R asymmetry in the ASE chemosensory neurons of C. elegans as a paradigm. This bilaterally symmetric neuron pair is functionally lateralized in that it senses a distinct class of chemosensory cues and expresses a putative chemoreceptor family in a L/R asymmetric manner. RESULTS: We show that the directionality of the asymmetry of the two postmitotic ASE neurons ASE left (ASEL) and ASE right (ASER) in adults is dependent on a L-/R-symmetry-breaking event at a very early embryonic stage, the six-cell stage, which also establishes the L/R asymmetric placement of internal organs. However, the L/R asymmetry of the ASE neurons per se is dependent on an even earlier anterior-posterior (A/P) Notch signal that specifies embryonic ABa/ABp blastomere identities at the four-cell stage. This Notch signal, which functions through two T box genes, acts genetically upstream of a miRNA-controlled bistable feedback loop that regulates the L/R asymmetric gene-expression program in the postmitotic ASE cells. CONCLUSIONS: Our results link adult neuronal laterality to the generation of the A/P axis at the two-cell stage and raise the possibility that neural asymmetries observed across the animal kingdom are similarly established by very early embryonic interactions.},
added-at = {2008-10-21T10:06:51.000+0200},
author = {Poole, R J and Hobert, O},
biburl = {https://www.bibsonomy.org/bibtex/25d10a8b9bf11eb41639073cc7a40e3b6/rouault},
doi = {10.1016/j.cub.2006.09.041},
interhash = {b19d8da545eb275acbd27fac50927e5a},
intrahash = {5d10a8b9bf11eb41639073cc7a40e3b6},
journal = {Curr Biol},
keywords = {"c asymmetry elegans" left notch right},
month = Dec,
number = 23,
pages = {2279-2292},
pmid = {17141609},
timestamp = {2008-10-21T10:06:51.000+0200},
title = {Early embryonic programming of neuronal left/right asymmetry in C. elegans},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17141609?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum},
volume = 16,
year = 2006
}