Tbx3, a member of the TBX2 subfamily of T-box gene family, encodes a transcription factor with a highly
conserved DNA-binding domain, which called T-domain.
Tbx3 is involved in morphogenesis and organogenesis in
vertebrates, such as limb development, heart remodeling, and neural placode differentiation. In the present study, a
full-length 2 908 bp
Tbx3 cDNA from
Acipenser baerii
(
AbTbx3) was obtained using RT-PCR and RACE technique,
which includes a 2 166 bp complete open reading frame encoding a putative peptide of 721 amino acids. AbTbx3 shares
73.5% identity with its human homolog. Particularly, the DNA-binding domain of AbTbx3 shared 95.2% identity with
human Tbx3. Phylogenetic analysis revealed that AbTbx3 was grouped with Tbx3s in other vertebrates, which were
clustered with Tbx2s and separated from Tbx4/5s. The predicted secondary and three-dimensional structures of the
T-domain of AbTbx3 were remarkably similar to human Tbx3. Through semi-quantity RT-PCR, the expression of
AbTbx3
was first detected at blastula stage during Siberian sturgeon embryonic development, increased gradually, reached its peak
at early tail-bud stage and then decreased slightly. In adult sturgeon,
AbTbx3 was strongly expressed in eye, brain, gill,
intestines, pectoral fin and pelvic fin, but not in liver, blood, heart, kidney and muscle. The whole mount
in situ
hybridization showed that
AbTbx3 was mainly expressed in the otic vesicle, hindbrain, dorsal notochord, pineal organ and
dorsal fin bud in the larvae of stage 37 and 43.
