volume 10 Number 9 1982 Nucleic Acids Research Organization of 6-crystalIin genes in the chicken

Double-stranded DNA was synthesized from 6-crystallln mRNA prepared from lens fibers of 15-day-old chick embryos and cloned at the Pst I site of the plasmid pBR322. Using the cloned cDNA and single-stranded cDNA as hybridiza-tion probes, a number of genomic DNA fragments containing 6-crystallin gene sequences have been cloned from the partial and complete EcoKl digests of chick brain DNA. One of the clones from the partial digests contains a DNA fragment that consists of four ficoRI fragments of 7.6 kb, 4.0 kb, 2.6 kb, and 0.8 kb. The gene sequences reside in the (5')7.6 kb- 0.8 kb- 4.0 kb(3') fragments. Electron microscopy has provided evidence that the cloned DNA fragment includes the entire gene sequences complementary to 6-crystallin mRNA except for the 3 ' terminal poly (A) tail, and that the 6-crystallin gene is interrupted by at least 13 Intervening sequences. Another clone contains a genomic fragment that consists of two £coRI fragments of 3.0 kb and 11 kb. The DNA fragment in the latter clone represents a different 6-crystallin gene