Long range restriction analysis of the bovine casein genes

Pulsed field gel electrophoresis (PFGE) was used to
analyse the organization of the bovine as1, as2, a and
x casein genes. High molecular weight DNA was
prepared from fibroblasts and lymphocytes embedded
in agarose and was digested with the restriction
endonucleases Clal, Sall, Smal, Xhol. The digestion
products were separated by PFGE, transfered to
nitrocellulose filters and hybridized to probes
corresponding to the cDNAs of the four bovine casein
genes. The casein genes were demonstrated to be
physically linked within a region of 300 kb, represented
by two adjacent Xhol fragments in fibroblasts and by
a single fragment in lymphocytes. A restriction map of
the casein locus was derived and the order of the genes
was shown to be x, as2, ,B, as1.