Embryogenic maize (Zea mays L.) callus cultures were transformed by microprojectile bombardment with a chimeric hygromycin phosphotransferase (HPT) gene and three transformed lines were obtained by selecting for hygromycin resistance. All lines contained one or a few copies of the intact HPT coding sequence. Fertile, transgenic plants were regenerated and the transmission of the chimeric gene was demonstrated through two complete generations. One line inherited the gene in the manner expected for a single, dominant locus, whereas two did not.

Cross-hybridization has been detected between corresponding regions of the genomes of bovine adenovirus type 3 and human adenovirus type 2. The most conserved region on the viral genomes encodes the hexon polypeptide. The nucleotide sequence of this region in bovine adenovirus type 3 has been determined. Comparison of the predicted amino acid sequences of the bovine adenovirus type 3 and human adenovirus type 2 hexon polypeptides reveals three regions of nonhomology. Adenoviridae is a family of viruses comprised of over 80 members, all sharing similar structural, serological, and biological properties. They have been isolated from species as diverse as amphibians, birds, and mammals and, in several cases, identified as clinically important pathogens. These viruses provide an ideal system to study host-virus interactions and viral evolution. However, comparative studies of the viral genome have been largely limited to human adenoviruses (6, 7, 20). So far, there have been only a few studies that have examined the relationship between adenoviruses of human and nonprimate origins (1, 12). Bovine adenovirus type 3 (BAV-3) was isolated by Darbyshire et al. in 1965 (4). The role of this virus in the bovine respiratory disease complex has been documented (5, 13). This virus is oncogenic in newborn hamsters (3) and is capable of transforming mouse and hamster cells in vitro (16, 23). BAV-3 shares a group-specific, complement-fixation antigen with human adenoviruses (2), and its basic biochemical properties have been described previously (11, 17). The purpose of this study is to map the regions of homology between the genome of BAV-3 and human adenovirus type 2 (HAV-2) and to compare the nucleotide sequences of the hexon-coding regions of these two viruses. To facilitate the study of the BAV-3 genome, we cloned into bacterial plasmids all the fragments of the viral DNA generated by restriction enzymes EcoRI, HindIll, or * Corresponding author.

We located the cleavage sites for restriction endonucleases EcoRI, HindIII, and BamHI on the genome of bovine adenovirus 7. Cross-hybridization at reduced stringency revealed two regions of homology shared by the DNA of human adenovirus 2 and bovine adenoviruses 7 and 3. These regions correspond to the hexon and the IVa2 protein genes of the human adenovirus. Another region of homology shared only by the human adenovirus and bovine adenovirus 7 corresponded to the penton or the polypeptide IIIa genes. These results allowed us to align the restriction map of bovine adenovirus 7 with respect to the other adenoviruses.