Isolation of novel genes expressed position-specifically in mouse embryo

During embryonic development, cells signal to each other, regulate the fates of cells, and eventually form a pattern of a particular animal. To isolate novel signalling developmental control genes, differential display (DD) RT-PCR was performed. Mouse embryos at the mid-gastrulation stage were isolated and sliced into eight pieces along the anterior-posterior (A-P) axis, and total RNAs were isolated from each segment and used for DDRT-PCR. The bands expressed differentially (decreasing or increasing expression along the axis, or head-, trunk- or tail-specific expression, etc.) along the A-P axis were selected and the cDNAs were analyzed after subcloning and sequencing. Out of 20 clones analyzed 9 clones turned out to be known developmental control genes such as forkhead-1, alpha-tropomyosin, Hoxd-11, sfrp-1 etc., whereas 11 were novel that have not yet been identified thus far. Most of the known genes screened here were developmentally regulated and differentially expressed during embryogenesis so that the novel genes could be good candidates for developmental control genes: two novel genes, G8B1 and C1A1 cloned from the head region, were expressed in temporally restricted manner, besides spatially restricted pattern of expression. These results altogether suggest that the novel genes expressed position-specifically during mid-gastrulation stage are likely to be putative developmental control genes which are involved in signalling the developmental cascade finally leading to a particular pattern of an animal.