Purpose: Because stage-specific genetic expression in human preimplantation development is not sufficiently studied, we have undertaken the construction of a subtraction complementary DNA (cDNA) library enriched for transcripts specific for human blastocysts.
Methods: For this purpose individual pools of cDNAs synthesized from four hatched blastocysts and three cleaving 8- to 10-cell embryos were exposed to suppression subtractive hybridization to minimize the presence of transcripts of housekeeping genes and other genes of maternal origin known to be expressed earlier in preimplantation development. Random clones of this library were sequenced and analyzed using the BLAST algorithm.
Results: The resulting subtraction library had a complexity of 3 x 10(5) and an average size of inserts of about 0.8 kb. Sequencing of random library clones revealed the following human genes: CD9 antigen, fatty acid binding protein, ferritin heavy chain, amyloid precursor, MAP kinase messenger RNAs, DNA clone 127H14, messenger RNA for diacylglycerol kinase, a sequence homologous to C1 inhibitor, messenger RNA for the KIAA0145 gene, and others.
Conclusions: The presence of these genes in human preimplantation development suggests expression specific to the blastocyst stage.