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Fig. 7. Injection of transcripts encoding the dominant negative xRARα2 result in a lack of sensory neurons. (A,B) Embryos injected with the dominant negative xRARα2∆393 into both cells at the two- cell stage have decreased numbers of sensory neuron axons, detected by the anti-HNK-1 antibody. (A) Uninjected embryo at the tailbud stage. Examples of sensory neuron axons are marked by arrowheads. (B) Embryo injected with control transcript xRARα2∆h*d has the normal complement of axons. (C) Embryos injected with 400 pg of xRARα2∆393 have very few sensory axons. Staining within the neural tube represents the cell bodies and axon tracts of anti-HNK-1 positive cells that are unaffected by xRARα2∆393 transcript injection. (D) Transverse section through an uninjected embryo showing bilateral primary sensory neurons (large arrowhead) and axons. (E) Transverse sections through a tailbud stage embryo co- injected into one cell at the two-cell stage with xRARα2∆393 and synthetic RNA encoding β-galactosidase. At the tailbud stage the embryos were assayed for both β-galactosidase activity (blue stain) and with the anti HNK-1 antibody to detect sensory neurons (brown). β-galactosidase activity acts as a lineage tracer to identify those parts of the embryo that received the coinjected synthetic transcripts. Only regions that did not receive injected transcripts developed primary sensory neurons (large arrowhead), although anti-HNK-1 staining is still seen in axon tracts and in some interneurons (small arrowhead). In addition, the ventral neurocoel is consistently displaced towards the uninjected side of the embryo. |
