Expression of the organizer specific homeobox gene Goosecoid (gsc) in porcine embryos

The homeobox gene goosecoid is one of the first genes expressed in the orga nizer region of vertebrates and specifies future dorsal regions along the a nterior/posterior axis of the embryo. Goosecoid (gsc) expression marks the posterior end of the anterior/posterior axis and might be a good marker to visualise early events in embryonic axis formation and differentiation proc esses in the epiblast at the onset of gastrulation. The aim of the present study was to evaluate gsc expression in porcine embr yos. For this the homeobox containing region of the porcine gsc was isolate d using RT-PCR. The sequence of the PCR product appeared to be highly homol ogous to the sequence in the mouse, human, and chicken. We concluded that t he isolated region represents part of the porcine gsc messenger. Relative levels of gsc expression were estimated in porcine embryos from da y 9 to day 12 of pregnancy. Gsc was expressed in embryos of all ages and lo calisation on one side of the embryoblast was demonstrated with in situ hyb ridisation on whole mount embryos at day 10 of pregnancy. In embryos collec ted at day 13 of pregnancy gsc expression was localised anterior to the pri mitive streak. The correlation between embryo size and level of gsc express ion was low. Levels and pattern of expression varied within and between lit ters collected at similar days of pregnancy. It is concluded that gsc expre ssion can be used as an early marker of differentiation and to describe emb ryo diversity in the pig. (C) 2000 Wiley-Liss, Inc.