ASGL, ASGR

Type: Sensory neuron (chemosensory (gustatory))
In MoW: ASG
Male Wiring Project: ASGL, ASGR
In Wormbase: ASG, ASGL, ASGR
Lineage: AB plaapapap, AB praapapap
Location: Lateral ganglia of head
Description: Amphid neurons, single (AsG) ciliated endings, Like all other amphid neurons, ASG are born near the presumptive nose of the embryo during development. They then anchor a short projection there, after which the cell body migrates away, stretching the dendrite out behind it. This process is dependent on DEX-1 or DYF-7, secreted extracellular matrix proteins which act cooperatively for anchoring. In mutants lacking these proteins, the dendrite fails to anchor at the nose and is dragged along with the migrating cell body, giving rise to a short dendritic stub (Heiman and Shaham, 2010). ASG axon projects into ring via amphid commissure from ventral ganglion and makes diverse synaptic connections in ring neuropil.
Developmental default state of the ASG neurons is AWA-like, and this fate must be repressed in order for the ASG neurons to adopt ASG fate. ALR-1 acts in parallel to UNC-130 and upstream of LIN-11 to specify the AWA and ASG neurons.
(Melkman and Sengupta; Sarafi-Reinach and Sengupta, 2000)
Neurotransmitter/ Neuropeptide:
- Glutamate
- Serotonin (under hypoxic conditions)
- FLP-6; FMRFamide-like neuropeptide
- FLP-13; FMRFamide-like neuropeptide
- FLP-22; FMRFamide-like neuropeptide




- INS-1; insulin-like peptide, orthologous to human insulin
(Pereira et al., 2015; Pocock and Hobert, 2010; Li and Kim, 2008)
Innexin expression:
- INX-4 (in early larva)
(Altun et al., 2009)
Receptor expression:
- DOP-4; human D1-like dopamine receptor
- GCY-15; Transmembrane receptor guanylate cyclase
- GCY-21; Transmembrane receptor guanylate cyclase
- NPR-1; receptor for flp-18- and flp-21-encoded peptides
- NPR-5; receptor for flp-3 and flp-18 encoded peptides
- NPR-15; neuropeptide receptor
- OSM-9; TRPV (transient receptor potential channel, vanilloid subfamily; mammalian capsaicin receptor-like channel)- cation selective
- TYRA-2; tyramine receptor
(Wormbase; Mills et al., 2012; Altun, 2011; Ortiz et al., 2006; Rex et al., 2005; Sugiura et al., 2005; Coates & De Bono, 2002; Colbert et al., 1997; O. Hobert, pers. comm.)
Function:
- Chemotaxis to water soluble attractants including Na+, Cl-, cAMP, biotin and lysine. Under normoxic conditions, simultaneous ablation of all amphid and phasmid neurons except ASE spares chemotaxis, indicating that the role of ASE in water-soluble chemotaxis is the most important. In the absence of ASE neurons, ADF, ASG, ASI, ASK, and ASJ carry out a weak residual response (Bargmann, 2006). However, under hypoxic conditions, an additional, latent circuit involving ADF and ASG is activated for processing the chemosensory information; downstream of ADF and ASG, pharyngal neuron M4 and AQR/PQR/URX function in processing this information towards behavioral response (Pocock and Hobert, 2010)
-Control entry into dauer stage and life span regulation; ADF, ASI and ASG inhibit entry into dauer stage while ASJ and ASK promote dauer entry (Kim et al., 2009; Ouellett et al., 2008; Schackwitz et al., 1996; Bargmann and Horvitz, 1991). Functional loss of ASI and ASG promotes lifespan and ablation of ASJ and ASK suppresses this effect (loss of ADF function does not prolong lifespan). This lifespan modulation is dependent on hormonal signalling via DAF-2 (insulin receptor homolog) which negatively regulates DAF-16 (FOXO transcription factor)(Alcedo and Kenyon, 2004)


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ASGL (AB plaapapap) development in the embryo.
Dorsal view. Bottom is left side of the embryo. Spheres indicate individual nuclei. Black sphere: ancestors of ASGL; dark grey spheres: apoptotic cells; other cells follow the WA color code (after they acquire specific cell or tissue identities). 0 min is fertilization. Click on the movie for higher resolution rendition (by A. Santella & Z. Bao).

 
 

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ASGR (AB praapapap) development in the embryo.
Dorsal view. Bottom is left side of the embryo. Spheres indicate individual nuclei. Black sphere: ancestors of ASGR; dark grey spheres: apoptotic cells; other cells follow the WA color code (after they acquire specific cell or tissue identities). 0 min is fertilization. Click on the movie for higher resolution rendition (by A. Santella & Z. Bao).


 
 

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3D reconstruction of the anterior sensory endings (cilia and dendrites) from high resolution serial section transmission electron micrographs (ssTEMs).
Bar 1 μm. Color code for the sensory endings is shown on the right-colors do not follow the WA color code. To expand, double click on the video, to return to original size, click "esc" (Doroquez et al., 2014)

 
 
 

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3D reconstruction of all amphid neuron cilia and associated socket and sheath cell processes.
Modeled from serial section transmission electron micrographs
(ssTEMs). Bar 1 μm. Color code for the sensory endings is shown on the left-colors do not follow the WA color code. To expand, double click on the video, to return to original size, click "esc" (Doroquez et al., 2014)

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