Transcription of homeobox-containing genes detected in cDNA libraries derived from human unfertilized oocytes and preimplantation embryos

Genes containing the evolutionarily conserved homeodomain sequence encode a family of DNA-binding transcription factors whose functions are crucial fo r embryonic development in vertebrates, invertebrates and plants. We descri be the detection and analysis of transcripts of homeobox-containing genes p resent in cDNA libraries generated from human unfertilized oocytes, single cleavage stage embryos (2-cell, 4-cell, 8-cell and blastocyst) and a 10-wee k old whole fetus. Using degenerate primers derived from sequences within h elix 1 and helix 3 of the highly conserved region of the Antennapedia-class homeodomain, a 166 bp band was detected in all the cDNA libraries tested. Subcloning of the oocyte-derived band revealed that it contained a heteroge neous group of 166 bp fragments. Sequence analysis of 40 independent clones demonstrated the presence of HOXA7, HOXD8, and HOXD1 sequences, the ubiqui tously expressed POU family member, OCT1, and HEX, a homeotic gene expresse d in haematopoietic cells.