- Title
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Control of cell migration in the zebrafish lateral line: Implication of the gene "Tumour-Associated Calcium Signal Transducer," tacstd
- Authors
- Villablanca, E.J., Renucci, A., Sapede, D., Lec, V., Soubiran, F., Sandoval, P.C., Dambly-Chaudiere, C., Ghysen, A., and Allende, M.L.
- Source
- Full text @ Dev. Dyn.
Localization of TACSTD protein. Zebrafish embryos were injected with myc fusion mRNAs, allowed to develop for 12 hr, and developed with an anti-myc antibody. A: Zebrafish tacstd-myc fusion mRNA was injected and embryonic cells were visualized under confocal microscopy; nuclei were labelled with propidium iodide (red) and the anti-myc antibody was detected with an Alexa fluorescent secondary antibody (green). B: Same as in A, but propidium iodide was not added. Note expression localized to membranes and to the perinuclear region. C: Injected mRNA corresponds to myc-tagged SKIP protein, a transcription factor localized to the nucleus. |
Developmental expression of tacstd. A: RT-PCR detection of tacstd message at 0, 6, 24, 48 haf, 6 daf, and adult (Ad) stages. Amplification of Wnt5a message is used as a positive control. The adult mRNA sample was contaminated with genomic DNA as amplification of genomic sequence produces a larger product (labelled as "genomic"). B-D: Whole mount in situ hybridization using a tacstd riboprobe. Embryos were processed for hybridization at 23 (B), 28 (C), and 48 haf (D). E-G: Neuromasts of in situ hybridized embryos. Probes used were tacstd (E), ath1 (F), or both probes (G). H,I: tacstd expression in the anterior lateral line (H) or posterior lateral line (I) primordia. Arrows indicate direction of migration. Dotted circles demarcate cells showing a rosette pattern, which is coincident with strong expression of tacstd. Expression to the left of the primordium in I is a recently deposited proneuromast. ALL, anterior lateral line; L1-5, posterior lateral line neuromasts; O1,2, otic neuromasts; OP, olfactory placode; OV, otic vesicle; PLL, posterior lateral line; prim, primordium. |
Embryonic posterior lateral line labeled by 4-Di-2-ASP, a marker of differentiated hair cells (A, B, and F) or by uncaging the primordium (C-E). A: Wild type embryo with the normal pattern of five neuromasts along the horizontal myoseptum (L1-L5) and two terminal neuromasts (ter). B: Morphant embryo where all PLL neuromasts are missing. C: Uncaging the primordium at the position marked by the asterisk in a wild type embryo reveals the neuromasts (L1-5 and ter) and interneuromastic cells (arrows). D: Uncaging in a morphant reveals that the primordium has reached the tip of the tail (arrowhead) but no neuromasts have been deposited. E,F: In a partial morphant where four clusters have been deposited, including a terminal one (E), each cluster has differentiated hair cells on the next day (F). PHENOTYPE:
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Alkaline phosphatase labeling of neuromasts. A: Normal pattern of neuromasts in a 2-day-old embryo. L1-L5 and the terminal neuromasts are derived form primI. D1, the first neuromast of the dorsal line, is derived from primII. B: Normal pattern in a 6-day-old larva. Consecutive primI neuromasts are connected by a thin trail of interneuromastic cells. Four additional neuromasts have been added by primII: LII.1-LII.4. The dorsal line comprises three additional neuromasts along the dorsal midline (out of focus). C: The trail of primI interneuromastic cells (INC) is continuous with the primI neuromast L1 but appears pushed away by the derivatives of primII (D1 and LII.1). D,E: The phosphatase activity reveals neuromast anisotropy, with the primI neuromasts being polarized along the antero-posterior axis while the primII neuromasts are polarized in a dorso-ventral direction (double arrows). Scale bars = 1 mm (A,B), 250 μm (C-E). |
Effect of tacstd inactivation on secondary lateral line formation. A: A normal 6-day-old larva showing three primII neuromasts (LII.1, LII.2, and LII.3). B,C: Two morphant embryos showing a strong phenotype. B: One lateral and two terminal primI neuromasts are present. The primII neuromasts have formed normally (LII.1-LII.4). C: No primI neuromast is present on the focused side of the embryo; two lateral and one terminal primI neuromasts are present on the other side as indicated. This embryo also shows the stereotyped head defect present in about 30% of the embryos. Note that in A and C, the D1 neuromast has been dislodged during manipulation. This rarely happens and can easily be detected because a rim of labelled cells remains attached to the epidermis, as can be faintly seen at this low magnification in A. PHENOTYPE:
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