ISOLATION OF A DEVELOPMENTALLY-REGULATED EXPRESSED SEQUENCE TAG FROM BLADDER TISSUE USING THE MESSENGER-RNA DIFFERENTIAL DISPLAY

In order to gain insight into the molecular and cellular events that g overn the structural and the functional properties in developing organ s, we have conducted a study to identify genes that have a temporally- restricted expression in the bladder wall during fetal development. We utilized the mRNA differential display technique and compared the pat tern of gene expression during the first, the second and the third tri mester of gestation. We cloned and sequenced a cDNA fragment (bld-10) which was expressed during the second and third trimester but consiste ntly absent during the first trimester. The bld-10 sequence is not rel ated to any known gene in the GenBank database but has significant hom ology (89%) with human expressed sequence tag (EST) that has been clon ed from human fetal heart and brain libraries. When used in Northern-b lot hybridization as a probe, the fragment bld-10 generates two hybrid ization signals of 3.1 and 4.0 kb, that are minimally expressed during the first trimester of gestation and upregulated in the second and th ird trimester. Differential expression of this gene may be responsible for some of the profound changes which occur during organ development .