The long‐term immunological effects of alloferon and its analogues in the mealworm Tenebrio molitor

Abstract

The subject of this article is a search for the long-term immunological effects of alloferon and 3 structural analogues of alloferon, which were earlier characterized by the highest pro-apoptotic activity in Tenebrio molitor. The differences in the actions of these peptides on immune response were observed. Alloferon increased nodulation and significantly phenoloxidase activity in the hemolymph of experimentally infected T. molitor. However, [Phe(p-NH ) ]- and [Phe(p-OMe) ]-alloferon strongly inhibited cellular and humoral defense of the mealworm against Staphylococcus aureus infection. One day after injection of these peptides, the specific biochemical and morphological hallmarks of apoptosis in bacteria-challenged hemocytes were visible; in contrast, 3 days after peptides injection in all hemocytes, caspase activation was not observed. However, these new, circulating hemocytes differed from the control and the peptide-untreated bacteria-challenged hemocytes. They had an increased adhesion that led to a separation of viable, anucleated fragments of hemocytes that retain the ability to adhere and to form long filopodia. The peptide-induced separation of hemocyte fragments may resemble the formation of platelets in mammals and perhaps play a role in sealing wounds in insects. The results of in vivo studies may suggest a long half-life of studied peptides in the hemolymph of mealworm. Moreover, we showed the importance of the N-terminal histidine residues at position one of the alloferon molecule for its immunological properties in insects. The results obtained here show that alloferon plays pleiotropic functions in insects.

Products Derived from Buchenavia tetraphylla Leaves Have In Vitro Antioxidant Activity and Protect Tenebrio molitor Larvae against Escherichia coli-Induced Injury

“…These samples were selected to be evaluated in a model of stress induced by heat-killed E. coli in T. molitor larvae. This insect has been used as a model organism in studies of microbial pathogenesis and drug development (antimicrobial, antivirulence, and immunomodulator agents) [27][28][29]. Several factors have supported the use of this animal.…”

“…Larvae of T. molitor (~100 mg) were randomly allocated into groups (n = 10). After anesthesia and disinfection, 10 µL of the most active samples (methanolic extract or fractions C and D; at 10 mg/kg or 20 mg/kg) were injected in the ventral membrane between the second and third abdominal segments (tail to the head) [29]. One hour after the sample inoculation, the larvae received 10 µL of heat-killed E. coli OP50 (optical density at 600 nm: 0.7).…”

Impairment of the immune response after transcuticular introduction of the insect gonadoinhibitory and hemocytotoxic peptide Neb-colloostatin: A nanotech approach for pest control

“…Nodule formation was studied according to a previously described method 32 . In brief, two hours after the injection or topical application of ND and ND- Neb -colloostatin solutions, beetles at various stages of development were anaesthetized again, washed in distilled water and disinfected and then injected with Staphylococcus aureus solution in physiological saline (1:500 v/v; 5 μL, formalin-fixed suspension of essentially nonviable S. aureus ; Sigma R S2014 Saint Louis, Missouri, USA).…”

Synergistic interaction between carvacrol and Bacillus thuringiensis crystalline proteins against Cydia pomonella and Spodoptera exigua

“…Nodule formation in the haemoceol of control and experimental caterpillars was studied according to the method described by Czarniewska et al (2018). Briefly, caterpillars anaesthetized and disinfected with ethanol were injected with Staphylococcus aureus (Sigma S2014 Saint Louis, Missouri, USA) suspension in physiological saline (2 ll, 2:1000 v/v) through the abdominal proleg.…”

“…In this work, we examined the in vivo effect of carvacrol and the mixture of carvacrol and bacterial Cry proteins on morphology, viability, and cellular immune response (phagocytosis and nodule formation) of the third instar of S. exigua caterpillars to determine whether carvacrol and a mixture of carvacrol with the bacterial toxins are cytotoxic to immunocompetent cells and affect insect immunity. For this purpose, we used a very sensitive haemocyte biotest that we previously developed, through which it is possible to detect changes in the morphology, adhesion, viability, and immunological function of haemocytes that can be induced by various biotic and abiotic factors (Czarniewska et al 2012(Czarniewska et al , 2018(Czarniewska et al , 2019a(Czarniewska et al , 2019bKuczer et al 2016;Konecka et al 2018a;Kowalik-Jankowska et al 2019). Our results should explain the mechanism of interaction between carvacrol and B. thuringiensis Cry proteins in the mixture against insects.…”