{'fraction_non_alphanumeric': 0.052658227848101265, 'fraction_numerical': 0.028860759493670885, 'mean_word_length': 4.760932944606414, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 1, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The Gene Structure of Cu/Zn-Superoxide Dismutase from Sweet Potato

SODs (superoxide:superoxide oxidoreductase, EC 1.15.1.1) catalyze the dismutation of superoxide to dioxygen and hydrogen peroxide to protect organisms from oxidative damage (Hassan, 1984). SODs are metalloproteins that are classified into three types (Mn-, Fe-, and Cu/Zn-SOD) depending on the metal found in the active site. In plants, the most prominent SODs are Cu/Zn isozymes. It has been shown that transgenic plants that overexpress chloroplastic Cu/Zn-SOD increase resistance to oxidative stress (Gupta et al., 1993) and the activity of plant SOD increases in response to a variety of environmental and chemical stimuli (Fridovich, 1986; Perl-Treves and Galun, 1991). Recently, increased levels of SOD activities resulting from differential regulation of individual SOD genes at the transcriptional leve1 were also reported (Perl-Treves and Galun, 1991). Many plant SOD cDNAs from leaf or seedling have been studied, but information concerning the Cu/Zn-SOD gene from root tissue is limited. Previously, we cloned and sequenced a full-length cytosolic Cu/Zn-SOD cDNA from sweet potato root (Lin et al., 1993). In this paper, we report the structural features of a Cu/Zn-SOD gene from the same tissue (Table I). Positive clones derived from the cytosolic Cu/Zn-SOD gene were characterized. The total sequence is 3950 bp long. Structural alignment showed perfect agreement between the cDNA sequence and the open reading frame of genomic DNA constructed from eight exons. The coding sequence, comprising 456 bp, begins in the second and ends in the last exon. The genomic sequence was compared with SOD gene structures derived from eukayotes: human (2.3 kb, five exons, four introns, Levanon et al., 1985), Drosophila melanogaster (1.8 kb, two exons, one intron, Seto et al., 1987), Neurospora crassa (1.0 kb, four exons, three introns, Chary et al., 1990), and rice (2.0 kb, eight exons, seven introns,