Structure of the murine TNFα transgenic construct and confirmation of genotype. The structure of the murine TNFα transgenic construct is illustrated in Panel a. An example of polymerase chain reaction (PCR) products stained with ethidium bromide to confirm the genotype of the TNFα-transgenic (TNFα-Tg) rat is shown in Panel b. Clear boxes in the drawing of the transgenic construct represent untranslated sequences from the mouse TNFα gene, black boxes indicate the coding region of the TNFα gene, and the gray box (including the remainder of the EcoRI to SalI fragment) represent the human β-globin 3' fragment. BS indicates pBluescript vector. Panel b shows PCR products in tail snip tissue taken from a TNFα-Tg rat (Lane a), a non-transgenic littermate (Lane b), and a Sprague-Dawley rat (Lane c). A 501 bp fragment of the murine TNFα gene was detected only in the transgenic rat.