GENETIC-VARIABILITY IN WHITE LEGHORNS REVEALED BY CHICKEN LIVER EXPRESSED SEQUENCE TAGS

A total of 92 expressed sequence tags from chicken liver (CLEST) were searched for homology with known genes. Among the CLEST, 29% had no se quence similarities with known genes, 34% showed sequence similarity t o rRNA, 9% to mitochondrial genes, 23% to known nuclear genes, and 5% to human expressed sequence tags. Among the nuclear CLEST (excluding r RNA), clones with sequence similarity to aldolase B were represented f our times, whereas all the other clones represented unique genes. The presence of MspI and TaqI restriction fragment length polymorphisms (R FLP) associated with CLEST were analyzed by bulk Southern blotting in 16 strains of White Leghorn chickens derived from five different genet ic bases. No RFLP were observed with rRNA CLEST and a single MspI RFLP was observed with mitochondrial CLEST. The nuclear CLEST with sequenc e similarity to known nuclear genes were grouped into two classes on t he basis of their involvement in intermediary metabolism. Among the ni ne genes coding for metabolic enzymes, all but one were polymorphic at MspI and/or TaqI sites in at least one of the strains, whereas among the other genes six of nine were polymorphic. The average frequency of clones revealing RFLP per cDNA clone and restriction enzyme for the t wo classes were 0.7 and 0.3, respectively. The analysis indicated that in White Leghorns, RFLP markers in the vicinity of nuclear CLEST are relatively frequent. Further, RFLP in the vicinity of genes coding for metabolic enzymes were significantly more frequent than near genes co ding for other proteins.