Generating Neural Diversity Flashcards

Vocabulary flashcards focusing on key mechanisms of neuronal diversity generation, including terminal selectors, spatial patterning, temporal coordinates, cell-cell signaling, stochastic fate choice, and spinal cord/retinal development.

Terminal Selectors

Transcription factors that are expressed at the end of cell lineages and maintained throughout a neuron's lifetime to establish and maintain cell-type-specific identity and gene expression.

unc-86

A transcription factor in C. elegans expressed specifically in the Q1.p progenitor cell that is required for touch cell differentiation; mutations cause Q1.p to fail to produce mechanosensory neurons and retain its mother cell identity.

ASE Neurons

A bilateral pair of gustatory neurons in C. elegans (ASEL and ASER) that exhibit structural symmetry but function asymmetrically, with ASEL sensing sodium and ASER sensing chloride.

che-1

A terminal selector transcription factor expressed in both ASEL and ASER gustatory neurons in C. elegans that acts alongside asymmetric transcription factors to specify sodium versus chloride sensory pathways.

die-1

A transcription factor expressed specifically in ASEL neurons of C. elegans that works alongside Che-1 to activate the sodium-sensitive sensory pathway.

cog-1

A transcription factor expressed specifically in ASER neurons of C. elegans that works alongside Che-1 to activate the chloride-sensitive sensory pathway.

Spatial Positioning

A mechanism of cell fate determination where positional information along body axes (such as anterior-posterior Hox gene stripes) provides neuroblasts with specific regional identities.

Temporal Coordinates of Determination

A cell fate specification mechanism governed by the timing of neuroblast divisions, wherein sequential transcription factors in neuroblasts activate the next factor and inhibit the prior factor to yield distinct progeny over time.

Ommatidium

An individual visual unit of the insect compound eye containing 8 photoreceptor cells (R1–R8) and 11 pigment cells that optically isolate neighboring units.

atonal (Ato)

A proneuronal transcription factor initially expressed in all cells of the Drosophila eye disc, where high expression marks cells committed to becoming R8 founder photoreceptors.

spineless

An intrinsic transcription factor in Drosophila that acts stochastically as a cell-fate coin-flipper to define a fixed $35:65$ ratio of Rh3- to Rh4-expressing R7 photoreceptors across ommatidia.

Sonic Hedgehog (Shh)

A morphogen secreted by the ventral floorplate and underlying notochord that forms a concentration gradient to pattern the dorsal-ventral axis of the vertebrate neural tube.

Class I Homeodomain Genes

A set of transcription factors in the vertebrate neural tube (e.g., Pax6) whose expression is repressed by Sonic Hedgehog (Shh) signaling.

Class II Homeodomain Genes

A set of transcription factors in the vertebrate neural tube (e.g., Nkx2.2, Nkx6.1) whose expression is activated by Sonic Hedgehog (Shh) signaling.

pMN Domain

A specific ventral progenitor domain in the spinal cord defined by co-expression of Nkx6 and Pax6 that gives rise uniquely to motor neurons.

Olig2

An essential transcription factor activated in the pMN progenitor domain that drives motor neuron differentiation by inducing downstream factors such as Mnr2, Hb9, Lim3, and Isl1/2.

Lateral Motor Column (LMC)

A spinal motor column whose motor neurons express specific combinations of LIM homeodomain factors and innervate limb musculature.

Medial Motor Column (MMC)

A spinal motor column whose motor neurons express specific LIM homeodomain factors (such as Lhx3 and Lhx4) and innervate axial trunk musculature.

Retinal Histogenesis

The sequential generation of distinct retinal cell types across defined developmental windows, progressing from early-born types (ganglion cells, horizontal cells, cones) to late-born types (rods, bipolar cells, Müller glia).

Cell Transplantation Assay

An experimental technique used to evaluate cell fate autonomy by transferring progenitor cells into a new host environment to test whether their fate is intrinsically determined or environmentally modified.