WormBase Tree Display for Expr_pattern: Expr1590

Expr1590 Expression_of: Gene: WBGene00006746
    Reflects_endogenous_expression_of: WBGene00006746
  Expression_data: Anatomy_term (42)
  Type: Reporter_gene
  Pattern: Early Expression by Ventral Epidermoblasts: Ventral epidermoblasts P1/2-P11/12 are the first cells to express UNC-6::HA during embryogenesis. Netrin becomes detectable in the cytoplasm of these twelve cells soon after their births (circa 230 min) and before they form into regular rows. This staining gradually decreases in intensity as the cells spread ventrally, forming two symmetrical rows. At the completion of neurulation, soon after these rows have come together along the ventral midline, cytoplasmic staining is no longer detectable.
    Expression by Larval Ventral Cord Motorneurons: Postembryonic motorneurons VA2 to VA12 and VB3 to VB11 express UNC-6::HA in the ventral nerve cord. Netrin becomes detectable in these cells soon after their births at the end of the first larval stage. This expression continues through the adult stage. After hatching, the C. elegans larva increases about 5-fold in both length and circumference before becoming an adult. Six axons (AVAL, AVAR, AVBL, AVBR, AVG, and PVQR) in the right longitudinal tract and one axon (PVQL) in the left tract provide a continuous source of UNC-6 in the ventral nerve cord. Near the end of the first larval stage, the twenty postembryonic motorneurons (VA2VA12, VB3VB11) provide a further source of UNC-6 in the right tract. These motorneurons could maintain and sharpen the proposed gradient of netrin in the basement membrane of the epidermis and skew its peak farther to the right of the ventral midline.
    Expression by Lateral Ring and Lumbar Ganglia Neurons: Paired neurons AVA, AVB, and PVQ express UNC-6::HA in the lateral and lumbar ganglia, respectively. Born circa 300 min, netrin does not become detectable in these cells until about 3-fold elongation. Netrin expression then continues through the larval and adult stages. After axogenesis begins, PVQ itself expresses UNC-6.
    Expression by Midline and Asymmetric Neurons in the Developing Nerve Cord: Positioned at the anterior and posterior ends of the developing ventral nerve cord, respectively, the midline neurons AVG and PVT express UNC-6::HA. Netrin becomes detectable in the PVT neuron soon after its birth (circa 290 min). At this time, PVT is positioned on the ventral midline of the body wall just anterior to the developing rectum. Netrin expression is transient; UNC-6::HA is no longer detectable in this cell by 3-fold elongation. By then, PVT has shifted to its mature position as the most anterior cell in the preanal ganglion. Born circa 290 min, AVG does not express UNC-6::HA until about 3-fold elongation. AVG is positioned on the ventral midline in the retrovesicular ganglion at this time. Netrin expression then continues through the larval and adult stages. Besides AVG, a second neuron in the retrovesicular ganglion, RIFL (born circa 410 min), also expresses UNC-6::HA from about 3-fold elongation through adult. Interestingly, no UNC-6::HA expression is ever observed in the bilateral homolog RIFR.
    Expression by Sheaths in the Developing Head: All six inner labial and both ventral cephalic sheaths express UNC-6::HA in the early neurula. Netrin becomes detectable in these cells soon after their births (circa 310 min). At this time, the inner labial sheaths are clustered together just anterior to the developing pharynx. As the head depression forms around comma stage, the cell bodies move anteriorly toward the sensillar rudiments, revealing processes trailing back to the developing nerve ring. The endfeet form a more-or-less complete path around the pharynx that anticipates the anterior margin of the nerve ring. UNC-6::HA is detectable along the entire cell body and process at this time. As the embryo elongates, the cell bodies initially stay near the sensillar rudiments at the tip of the head. Presently, as judged by UNC-6::HA staining, the processes no longer reach the developing nerve ring. By inference, they fail to stretch apace with the rapid elongation of the head. As the pharynx elongates, the cell bodies assume their mature positions, typically just anterior or posterior to the metacorpus. Netrin expression is transient; only weak staining of UNC-6::HA is detectable in these cells beyond 3-fold elongation. The sheath processes appear to provide a scaffold of netrin-labeled pathways that support and guide labial axons to the nerve ring. Moreover, their endfeet could form a ring-shaped substratum for axons within the ring itself. The cephalic sheaths are positioned dorsally and ventrally just anterior to the developing nerve ring. In the early neurula, these cells extend sheetlike processes that apparently anticipate the outer surface of the ring neuropil. At this time, UNC-6::HA is detectable throughout the cell body and processes of the ventral cephalic sheaths. Netrin expression is transient; UNC-6::HA is no longer detectable in these cells by 3-fold elongation. Finally, no UNC-6::HA expression is ever observed in the dorsal cephalic sheaths.
    Expression by a Midline Neuron in the Developing Pharynx: The midline neuron I5 expresses UNC-6::HA in the developing pharynx. Netrin becomes detectable in this cell soon after its birth (circa 280 min). Positioned on the ventral midline, I5 is the most posterior neuron in the pharynx at this time. Netrin expression is transient; UNC-6::HA is no longer detectable in the cell body after about 3-fold elongation, but staining in the axons persists somewhat longer.
  Picture: WBPicture0000009567
    WBPicture0000009568
    WBPicture0000009569
  Reference: WBPaper00002378
  Transgene: WBTransgene00004820