<i>In silico</i> identification and expression analyses of catalases in <i>Tenebrio molitor</i>

Abstract

Agricultural intensification has led to significant increases in production, but the overuse of pesticides and associated hazards pose threats to biodiversity and ecological functions. Catalase (CAT), a key antioxidant enzyme, plays a crucial role in alleviating oxidative stress by directly interacting with toxins. In this study, we identified three CAT isoforms in Tenebrio molitor (TmCAT-iso1, TmCAT-iso2 and TmCAT-iso3). These CATs possess a CAT domain, tetramer interface sites and a heme-binding pocket. We examined the expression of Tm catalases across all developmental stages and in specific tissues using quantitative real time polymerase chain reaction (qRT-PCR) experiments. Our findings demonstrate that TmCAT-iso1 and TmCAT-iso3 exhibit peak expression in young and late larval stages, respectively, whereas TmCAT-iso2 shows peak expression during the egg and pre-pupal stages. Tissue distribution analysis revealed the high expression of TmCAT-iso1 and TmCAT-iso2 in larval hemocytes, whereas TmCAT-iso3 is predominantly expressed in larval Malpighian tubules. Furthermore, injection with chlorantraniliprole significantly elevated mRNA expression levels of TmCAT-iso1, TmCAT-iso2, and TmCAT-iso3 in larval groups, compared with control groups. Our study highlights the distinct developmental stages and tissues where TmCATs are expressed. We also elucidated the effects of pesticide application on the expression of each TmCAT, revealing the physiological characteristics of CATs in response to these pesticides, which are dose- and time-dependent in T. molitor.