Genomic organization and transcription of superoxide dismutase genes ( sod1 , sod2 , and sod3b ) and response to diazinon toxicity in platyfish ( Xiphophorus maculatus ) by using SOD enzyme activity.

The aim of this study is to determine the effects of 50% of 96 h LC 50 (5.25 ppm) diazinon on the expression of superoxide dismutase (SOD) enzyme genes ( sod1 , sod2 , and sod3b ) and SOD enzyme activity at the end of 24, 48, 72, and 96 h in platyfish liver and gill tissues. To this end, we determined the tissue-specific distribution of sod1 , sod2 , and sod3b genes and performed in silico analyses in platyfish ( Xiphophorus maculatus ). It was determined that malondialdehyde (MDA) level and SOD enzyme activity were increased in the liver [(43.90 EU mg protein -1 (control), 62.45 EU mg protein -1 (24 h), 73.17 EU mg protein -1 (48 h), 82.18 EU mg protein -1 (72 h), 92.93 EU mg protein -1 (96 h)] and gill [(16.44 EU mg protein -1 (control), 33.47 EU mg protein -1 (24 h), 50.38 EU mg protein -1 (48 h), 64.62 EU mg protein -1 (72 h), 74.04 EU mg protein -1 (96 h)] tissues of platyfish exposed to diazinon, while the expression of the sod genes was down-regulated. The tissue-specific distribution of the sod genes varied, with the tissues and the sod genes expression were being predominant in the liver (628.32 in sod1 , 637.59 in sod2 , 888.5 in sod3b ). Thus, the liver was considered a suitable tissue for further gene expression studies. Based on the phylogenetic analyses, platyfish sod genes can be reported to be orthologs of sod / SOD genes from other vertebrates. Identity/similarity analyses supported this determination. Conserved gene synteny proved that there are conserved sod genes in platyfish, zebrafish, and humans.