Stress-Induced Modulation of Lectin as a Physiological Response in the Larvae of Zophobas morio

Lectins, the glycan-binding proteins that are known to function as essential pattern-recognition receptors (PRRs) in the innate immune system of insects, also act as strategic modulators of physiological stress responses. An attempt is made here to demonstrate how chronic stress affects the lectin from the larvae of Zophobas morio, an adapter molecule in physiological response. The haemagglutination (HA) titer used to measure the activity of lectin revealed discrepancies in the larval serum of Z. morio after exposure to various stress conditions. Among the stress-induced treatment groups, except the control, the treatments exhibited a marked reduction in the HA activity from the larval serum of Z. morio. Examination of the haemagglutination inhibition (HAI) activity, which is used to assess the ability of specific sugars that inhibit this process, clearly showed that lectin from the larval serum of stress-induced groups had deteriorated in its binding ability to d-fucose and lactose. Pyriproxyfen (a juvenile hormone analog) mimics hormones exclusive to insects and is extremely target-specific. It induces physiological and cellular alterations in insects. Although the effects of pyriproxyfen on insect lectins are indirect, it acts through hormonal signaling to affect lectins. The relative quantitation of d-fucose-binding lectin (FBL) mRNA under various stress conditions in the larval fat body of Z. morio, analyzed through RT-qPCR, clearly indicated significantly lower levels of its expression, except for pyriproxyfen treatment. Molecular docking and simulation were performed to recognize the stability of the interaction between FBL and pyriproxyfen. These results revealed a significant binding characterized by high affinity through a strong amide bridge, and other non-covalent interactions, showing evidence for increased expression of lectin at doses of pyriproxyfen treatments as a measure of neutralization. On the whole, stressful environments bring swift and dynamic changes in the activity of lectin, including its expression in Z. morio larvae, revealing lectin as a vital constituent in response to physiological challenges.