Xenopus sybII; nervous system
Xenopus synaptobrevin II, Xl sybII, nucleic acid
Pictures from Anne Knecht and Richard Harland, text from Peter Good and
Anne Knecht.
Developmental Northern Blot for sybII. 
The cDNA corresponding to the sybII gene (17-30) was isolated in a screen
for markers of the embryonic nervous system. The gene has a maternal
component and is activated after gastrulation (Northern Blot). The cDNA
17-30 is a partial cDNA with the predicted protein being a member of the
synaptobrevin gene family. The 81 amino acid stretch encoded by the 17-30
cDNA is 96% identical to the corresponding region of the rat SYBII protein
(also referred to as VAMP2 for vesicle associated membrane protein 2),
indicating that 17-30 is the Xenopus homolog of SYBII. Given the
ubiquitous localization of this protein to synaptic vesicles and its
expression throughout the rat brain, Xenopus sybII should be a widely
expressed throughout the nervous system
Stage 26 
Stage 37
Spinal Cord X-section 
By whole mount in situ hybridization, sybII is not detectable by our
methods until stage 20, when it appears weakly in the spinal cord and
future trigeminal ganglion. As with nrp-1, expression in cranial ganglia
and nerves follows a sequence, though the timing is delayed from that of
nrp-1; sybII appears first in the trigeminal ganglion and nerves (stage
20-26), then the geniculate ganglion and facial nerve (stage 32), and last
vagus and glossopharyngeal nerves and ganglia (stage 38). Spinal cord
expression intensifies through the tailbud stages (Figure Stage 26); within
the spinal cord, staining is restricted to the outer layers on the ventral
side (Figure X-section). By stage 32 expression is beginning to extend
into the hindbrain, midbrain, and epiphysis, with very weak expression in
the forebrain and dorsal eye. Finally, by stage 38 sybII is strongly
expressed throughout the CNS (Figure Stage 38). The late onset of sybII
expression, the delayed expression in cranial nerves (relative to nrp-1),
the expression in ventral outer layers of the neural tube, and the very
late expression in the brain (a structure thought to differentiate quite
late) all suggest that sybII is only expressed by differentiated neurons,
as might be expected due to its role in synaptic vesicles .
- Reference: Knecht, A.K., Good, P.J., Dawid, I.B., and Harland,
R.M. (1995)Dorsal-Ventral Patterning and Differentiation of
Noggin-Induced NeuralTissue in the Absence of Mesoderm Development 121,
1927-1936.
Richter, K., H. Grunz, and I.B. Dawid. 1988. Gene
expression in the embryonic nervous system of Xenopus laevis. Proc. Natl.
Acad. Sci. 85:8086-8090. - Plasmid name; p17-30 (download restriction map)
- nrp-1a cDNA in
pBluescriptKS
- download
sequnce
- Genbank accession number; U16801.
- For in situ
probe cut with XbaI and transcribe with T3
- Available from Peter Good
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Stage 37
Spinal Cord X-section 
