Isolation and Characterization of Recombinant cDNA Clones Corresponding to Developmentally Regulated Genes in Pig Liver

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Abstract
To identify clones that corresponded to developmentally regulated genes in pig liver, recombinant cDNA libraries were constructed from early fetal (d 40), late fetal (d 110) and adult liver mRNA. Each library was screened by probing with total cDNA prepared from mRNA at different stages of development. Nine clones that gave distinct developmental patterns when hybridized to liver RNA isolated from various stages of development were subsequently isolated and partially sequenced. The cognate proteins for seven of these clones were identified by searching a national DNA sequence resource (Bionet) for similar sequences. Clones hybridizing to mRNA that was most abundant early in development were α fetoprotein, at α1 antiprotease, α globin and an unidentified clone. The mRNA for β and γ fibrinogen were most abundant perinatally. The abundance of mRNA for albumin, haptoglobin and a second unidentified clone was low in fetal liver, but increased to adult levels between birth and 3 d of age. These clones provide probes to study the relationship between factors affecting fetal growth and expression of specific genes throughout the development.