Isolation and characterization of the chicken ovomucoid gene.

The chicken ovomucoid gene has been isolated by screening a chicken DNA library with a plasmid containing ovomucoid mRNA sequences. Twelve recombinant phages carrying ovomucoid mRNA sequences were isolated. Two of them, extending farthest into the 5' and 3' direction respectively, were characterized by restriction mapping and Southern hybridization as well as by electron microscopic analysis of hybrids between the cloned DNA and ovomucoid mRNA. Seven intervening sequences interrupt the ovomucoid mRNA sequence in chromosomal DNA. From these data a minimal size of 5.6 kb can be estimated for the length of the ovomucoid gene.     

Isolation of the chicken middle-molecular weight neurofilament (NF-M) gene and characterization of its promoter.

We have isolated and sequenced genomic DNA clones covering the coding region of the chicken mid-size neurofilament (NF-M) gene and greater than 1 kb of its 5' upstream region. The NF-M gene contains two introns which both are located within the highly conserved C-terminal region of the rod domain. The 5' end of the corresponding mRNA was assigned to a G residue 40 nucleotides upstream of the translation start site and in appropriate distance from a potential TATA box. To functionally analyze the NF-M promoter, constructs carrying 112, 222, and 1026 nucleotides of the 5' upstream region in front of a luciferase reporter gene were tested for their capability to direct luciferase expression after transient transfection into various cell lines. Significant luciferase activity was recorded both in rat phaeochromocytoma (PC12) cells and murine fibroblasts. In PC12 cells, in which neurite outgrowth is induced by nerve growth factor (NGF), expression was stimulated up to 13-fold within 3 days of NGF treatment. This closely resembles expression of the endogenous NF-M gene in response to this hormone.     

Isolation and characterization of genomic clones covering the chicken vitellogenin gene

A series of overlapping recombinant clones, which cover the vitellogenin gene, has been isolated from a phage-lambda linked chicken gene library. The DNA of the overlapping clones spans 28 kb of contiguous DNA sequences in the chicken genome. Electron microscopic analysis of hybrids between vitellogenin mRNA and the genomic clones indicates that the chicken vitellogenin gene has a length of approximately 22 kb, about 3.8 times the size of the mRNA. The mRNA sequence is interrupted by at least 33 intervening sequences (introns). Comparison with the vitellogenin gene A2 from Xenopus laevis (Wahli et al., 1980, Cell 20: 107-117) indicates conservation of the number and length of the exons during evolution. Heteroduplex analysis reveals a short stretch of sequence homology between the genes from chicken and frog.