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Figure 1 Structure and expression pattern of XFLRT3. (a), Schematic
representation of XFLRT3. Signal peptide (red box); LRRNT, N-terminal
leucine-rich repeat cysteine flank; LRR, leucine-rich repeats; LRRCT,
C-terminal leucine-rich repeat; FNIII, fibronectin domain type III; TM,
transmembrane domain. (b) FLRT protein homology tree showing relationship
between Xenopus laevis, Fugu rubripes, mouse and human FLRT proteins.
(c) mRNA encoding Myc-tagged XFLRT3 was microinjected animally into all
blastomeres of a four-cell Xenopus embryo. Animal caps of stage-10 embryos
were prepared for immunofluorescence microscopy with an anti-Myc
antibody. Note labelling of the plasma membrane. (d–i) Expression pattern of
XFLRT3 (d–f) and XFGF8 (g–i) in Xenopus gastrulae (d, g, vegetal view),
neurulae, (e, h, anterior view) and tadpoles (f, i). (j, k) Regulation of XFLRT3
by FGF. In j, four-cell embryos were uninjected or microinjected into each
blastomere with 0.025, 0.125 or 0.25 ng XFD mRNA. Ventral marginal zone
(VMZ) fragments were cut from early gastrulae and analysed for expression of
XFLRT3 and Xbra at stage 11 by RT–PCR. −RT, minus reverse transcription
control sample; H4, histone H4 for normalization. In k, eight-cell embryos
were microinjected into all four animal blastomeres with increasing doses of
eFGF mRNA (1.25, 12.5 or 25 pg per blastomere) or FGF8 mRNA (2.5 or
20 pg per blastomere). Animal caps were excised from blastula embryos,
cultivated until stage 10 and analysed by RT–PCR for gene expression. The
‘Embryo’ lane indicates whole embryos. |
