Identification, characterization and expression analysis of superoxide dismutase genes in Dastarcus helophoroides (Coleoptera: Bothrideridae)

Dastarcus helophoroides, a predatory natural enemy of longhorned beetles, has a relatively longer lifespan compared to other insects. To determine the potential physiological roles of antioxidant enzymes superoxide dismutase (SOD) in longevity and aging of D. helophoroides, analyses including molecular information, bioinformatics research, phylogenetic relationship and expression patterns were combined for investigation. Four D.hSODs were classified into three groups: one cytoplasmic Cu/Zn-SOD, two extracellular Cu/Zn-SOD and one Mn-SOD, were identified and characterized by multiple alignments. All D.hSODs were highly homologous to SODs of Tribolium castaneum, and closely clustered together with SOD genes from insects in phylogenetic analyses. Comparison of the D.hSODs expression in different tissues, stages and age groups showed that the SOD transcripts could be detected in all examined specimens. The expression of D.hSODs revealed tissue-specificity with relatively high levels in the male reproductive system and head and low levels in female reproductive systems and midgut. Expression analyses of D.hSODs in different development stages demonstrated that D.hSOD1 and D.hSOD2 increased in 2nd and 5th instar larvae, whereas two extracellular Cu/Zn-SOD genes (D.hSOD3-a and D.hSOD3-b) were much more expressed in newly emerged adults. The expression fluctuations of D.hSODs during aging seemed to be less significant than during development, and exhibited relatively stable expression with an initial decline and then increased in older groups. The relatively stable and increased expression of D.hSODs may indicate a strong ability of SODs to eliminate oxidative damage products accumulated during aging and possibly retard aging. The research provides molecular biology and in vivo expression levels for future analysis of the SOD family in D. helophoroides and other insects, and provides a basis for further study about the SOD genes contribution on longevity of D. helophoroides.