An oligochaete homologue of the Brachyury gene is expressed transiently in the third quartette of micromeres.
We have isolated a Brachyury homologue (Ttu-Bra) from the oligochaete annelid Tubifex tubifex which displays a direct mode of development. Developmental RT-PCR analysis showed that Ttu-Bra transcripts are present in embryos at stages 9-11, 16 and 17, but undetectable at the remaining embryonic stages. Whole-mount in situ hybridization demonstrated that Ttu-Bra is expressed transiently in the third quartette of micromeres, which are located at the prospective stomodaeum (at stages 9-11). The second burst of Ttu-Bra expression occurs at the posterior end of stage 16 embryo that undergoes body elongation. Ttu-Bra-expressing cells, which are organized in a circle at stage 16, become aggregated at the proctodaeum at stage 17. Consistent with the results of the RT-PCR analysis, there is no sign of Ttu-Bra-expressing cells in embryos that undergo gastrulation during stages 12-15.
Kitakoshi
Tomohito
T
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-10, Nishi-8, Kita-ku, Sapporo 060-0810, Japan.
Shimizu
Takashi
T
D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D004625:Embryo, Nonmammalian; D005326:Fetal Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008954:Models, Biological; D008969:Molecular Sequence Data; D009835:Oligochaeta / Q000196:embryology / Q000235:genetics*; D010802:Phylogeny; D017385:Sequence Homology; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000378:metabolism; D000098908:Brachyury Protein
D005326:Fetal Proteins; D020825:T-Box Domain Proteins; D000098908:Brachyury Protein