Figure 3.
The human U7 sequence at 12p13 encodes a functional snRNA. (A) Xenopus oocytes were injected with H20 (lanes 2 and 3), anti-hnRNP A1 mRNA control oligonucleotide (lanes 4 and 5), or anti-U7 snRNA oligonucleotide (lanes 6 and 7). Four hours later, oocytes were injected with either a control plasmid and the mouse H2a-614 gene (lanes 2, 4, and 6) or plasmid pTT005, containing the putative human U7 gene (hU7) and the mouse H2a-614 gene (lanes 3, 5, and 7). Eighteen hours later, total RNA was prepared from oocytes and analyzed by S1 nuclease mapping using an assay that detects both processed (Proc) and unprocessed (Unproc) histone mRNA. NS, nonspecific transcript derived from the hU7 plasmid. Lane 1, pUC18 DNA digested with HpaII. (B) Schematic of the S1 nuclease assay used in A. The probe contains 34 nucleotides beyond the end of the histone mRNA followed by plasmid sequences that are not present in the transcript from the mouse histone H2a-614 gene.