In silico identification and expression analysis of superoxide dismutases in Tenebrio molitor.

Background: Insects encounter various environmental stresses, in response to which they generate reactive oxygen species (ROS). Superoxide dismutase (SOD) is an antioxidant metalloenzyme that scavenges superoxide radicals to prevent oxidative damage.

Objective: To investigate expressions of SODs under oxidative stress in Tenebrio molitor.

In silico identification and expression analyses of peroxidases in Tenebrio molitor.

Human advancements in agriculture, urbanization, and industrialization have led to various forms of environmental pollution, including heavy metal pollution. Insects, as highly adaptable organisms, can survive under various environmental stresses, which induce oxidative damage and impair antioxidant systems. To investigate the peroxidase (POX) family in Tenebrio molitor, we characterized two POXs, namely TmPOX-iso1 and TmPOX-iso2.

Effects of TmTak1 silencing on AMP production as an Imd pathway component in Tenebrio molitor.

Mealworms beetles, Tenebrio molitor, are the limelight next-generation food for humans due to their high nutrient contents. Since Tenebrio molitor is used as feed for pets and livestock in addition to their ability to decompose polystyrene and plastic waste, it is recognized as an insect with an industrial core value. Therefore, it is important to study the immune mechanism related to the development and infection of mealworms for mass breeding purposes.

IKKβ regulates antimicrobial innate immune responses in the yellow mealworm, Tenebrio molitor.

Toll and IMD pathways regulate antimicrobial innate immune responses in insect model systems. The transcriptional activation of antimicrobial peptides (AMPs) confers humoral immunity in the host against invaded pathogens. The IKK kinase complex (IKKα, IKKβ, and the regulatory subunit IKKγ/NEMO) centrally regulates the NF-κB response to various stimuli.

Innate Immune Response of Following Systemic Microbial Infection in .

Although Toll-like receptors have been widely identified and functionally characterized in mammalian models and , the immunological function of these receptors in other insects remains unclear. Here, we explored the relevant innate immune response of () against Gram-negative bacteria, Gram-positive bacteria, and fungal infections. Our findings indicated that expression was mainly induced by infections in the fat bodies, gut, Malpighian tubules, and hemolymph of young .

Trehalose Biosynthesis Gene Protects against Stress in the Initial Infection Stage of -Bean Bug Symbiosis.

Trehalose, a nonreducing disaccharide, functions as a stress protectant in many organisms, including bacteria. In symbioses involving bacteria, the bacteria have to overcome various stressors to associate with their hosts; thus, trehalose biosynthesis may be important for symbiotic bacteria. Here, we investigated the role of trehalose biosynthesis in the -bean bug symbiosis.

Proteolytic Activity of DegP Is Required for the Symbiont To Persist in Its Host Bean Bug.

Symbiosis requires the adaptation of symbiotic bacteria to the host environment. Symbiotic factors for bacterial adaptation have been studied in various experimental models, including the -bean bug symbiosis model. Previously identified symbiotic factors of symbionts of bean bugs provided insight into the host environment being stressful to the symbionts.

Immunological Roles of in Response to Systemic Infection in .

The antimicrobial roles of Toll-like receptors have been mainly identified in mammalian models and . However, its immunological function in other insects has yet to be fully clarified. Here, we determined the innate immune response involvement of encountering Gram-negative, Gram-positive, and fungal infection.

Current Status of Immune Deficiency Pathway in Innate Immunity.

Yellow mealworm () is a highly beneficial beetle that serves as an excellent source of edible protein as well as a practical study model. Therefore, studying its immune system is important. Like in other insects, the innate immune response effected through antimicrobial peptides production provides the most critical defense armory in .

IKKε Is Required to Confer Protection Against Gram-Negative Bacteria, by the Regulation of Antimicrobial Peptide Production in the Fat Body.

The inhibitor of nuclear factor-kappa B (NF-κB) kinase (IKK) is the core regulator of the NF-κB pathway against pathogenic invasion in vertebrates or invertebrates. IKKβ, -ε and -γ have pivotal roles in the Toll and immune deficiency (IMD) pathways. In this study, a homolog of IKKε (IKKε) was identified from RNA sequence database and functionally characterized for its role in regulating immune signaling pathways in insects.

Critical Roles of Spätzle5 in Antimicrobial Peptide Production Against in Malpighian Tubules.

The dimeric cytokine ligand Spätzle (Spz) is responsible for Toll pathway activation and antimicrobial peptide (AMP) production upon pathogen challenge in . Here, we indicated that Spz5 has a functional role in response to bacterial infections. We showed that the highest expression of is induced by .

Spz-like Plays a Fundamental Role in Response to but Not or Infection in via Regulation of Antimicrobial Peptide Production.

The cystine knot protein Spätzle is a Toll receptor ligand that modulates the intracellular signaling cascade involved in the nuclear factor kappa B (NF-κB)-mediated regulation of antimicrobial peptide (AMP)-encoding genes. Spätzle-mediated activation of the Toll pathway is critical for the innate immune responses of insects against Gram-positive bacteria and fungi. In this study, the open reading frame (ORF) sequence of from () identified from the RNA sequencing dataset was cloned and sequenced.

Current knowledge of immune priming in invertebrates, emphasizing studies on Tenebrio molitor.

Vertebrates rely on the most sophisticated adaptive immunity to defend themselves against various pathogens. This includes immunologic memory cells, which mount a stronger and more effective immune response against an antigen after its first encounter. Unlike vertebrates, invertebrates' defense completely depends on the innate immunity mechanisms including humoral and cell-mediated immunity.

IKKγ/NEMO Is Required to Confer Antimicrobial Innate Immune Responses in the Yellow Mealworm, .

IKK/NEMO is the regulatory subunit of the IκB kinase (IKK) complex, which regulates the NF-κB signaling pathway. Within the IKK complex, IKK/NEMO is the non-catalytic subunit, whereas IKK and IKK are the structurally related catalytic subunits. In this study, was screened from the RNA-Seq database and functionally characterized using RNAi screening for its role in regulating antimicrobial peptide (AMP) genes after microbial challenges.

Autophagy-Related Gene 8 () Is Required to Confer Anti-Bacterial Gut Immunity.

Autophagy is an important process by which pathogens and damaged or unused organelles are eliminated. The role of autophagy in development and the immune response to pathogens is well established. Autophagy-related protein 8 (Atg8) is involved in the formation of the autophagosome and, with the help of the serine protease Atg4, mediates the delivery of both vesicles and the autophagosome to the vacuole.

Burkholderia gut symbiont modulates titer of specific juvenile hormone in the bean bug Riptortus pedestris.

Recent studies have provided molecular evidence that gut symbiotic bacteria modulate host insect development, fitness and reproduction. However, the molecular mechanisms through which gut symbionts regulate these aspects of host physiology remain elusive. To address these questions, we prepared two different Riptortus-Burkholderia insect models, Burkholderia gut symbiont-colonized (Sym) Riptortus pedestris insects and gut symbiont-noncolonized (Apo) insects.

The lipopolysaccharide core oligosaccharide of plays a critical role in maintaining a proper gut symbiosis with the bean bug .

Lipopolysaccharide, the outer cell-wall component of Gram-negative bacteria, has been shown to be important for symbiotic associations. We recently reported that the lipopolysaccharide O-antigen of enhances the initial colonization of the midgut of the bean bug, However, the midgut-colonizing symbionts lack the O-antigen but display the core oligosaccharide on the cell surface. In this study, we investigated the role of the core oligosaccharide, which directly interacts with the host midgut, in the symbiosis.

Gut symbiotic bacteria stimulate insect growth and egg production by modulating hexamerin and vitellogenin gene expression.

Recent studies have suggested that gut symbionts modulate insect development and reproduction. However, the mechanisms by which gut symbionts modulate host physiologies and the molecules involved in these changes are unclear. To address these questions, we prepared three different groups of the insect Riptortus pedestris: Burkholderia gut symbiont-colonized (Sym) insects, Burkholderia-non-colonized (Apo) insects, and Burkholderia-depleted (Sym) insects, which were fed tetracycline.

A midgut lysate of the Riptortus pedestris has antibacterial activity against LPS O-antigen-deficient Burkholderia mutants.

Riptortus pedestris, a common pest in soybean fields, harbors a symbiont Burkholderia in a specialized posterior midgut region of insects. Every generation of second nymphs acquires new Burkholderia cells from the environment. We compared in vitro cultured Burkholderia with newly in vivo colonized Burkholderia in the host midgut using biochemical approaches.

An antimicrobial protein of the Riptortus pedestris salivary gland was cleaved by a virulence factor of Serratia marcescens.

Recently, our group demonstrated that the bean bug, Riptortus pedestris, is a good experimental symbiosis model to study the molecular cross-talk between the host insect and the gut symbiont. The Burkholderia symbiont is orally acquired by host nymphs from the environment in every generation. However, it is still unclear how Riptortus specifically interacts with entomopathogens that are abundant in the environmental soil.

Understanding regulation of the host-mediated gut symbiont population and the symbiont-mediated host immunity in the Riptortus-Burkholderia symbiosis system.

Valuable insect models have tremendously contributed to our understanding of innate immunity and symbiosis. Bean bug, Riptortus pedestris, is a useful insect symbiosis model due to harboring cultivable monospecific gut symbiont, genus Burkholderia. Bean bug is a hemimetabolous insect whose immunity is not well-understood.

Bacterial cell motility of Burkholderia gut symbiont is required to colonize the insect gut.

We generated a Burkholderia mutant, which is deficient of an N-acetylmuramyl-l-alanine amidase, AmiC, involved in peptidoglycan degradation. When non-motile ΔamiC mutant Burkholderia cells harboring chain form were orally administered to Riptortus insects, ΔamiC mutant cells were unable to establish symbiotic association. But, ΔamiC mutant complemented with amiC gene restored in vivo symbiotic association.

Burkholderia gut symbionts enhance the innate immunity of host Riptortus pedestris.

The relation between gut symbiosis and immunity has been reported in various animal model studies. Here, we corroborate the effect of gut symbiont to host immunity using the bean bug model. The bean bug, Riptortus pedestris, is a useful gut symbiosis model due to the monospecific gut symbiont, genus Burkholderia.

Purine biosynthesis-deficient Burkholderia mutants are incapable of symbiotic accommodation in the stinkbug.

The Riptortus-Burkholderia symbiotic system represents a promising experimental model to study the molecular mechanisms involved in insect-bacterium symbiosis due to the availability of genetically manipulated Burkholderia symbiont. Using transposon mutagenesis screening, we found a symbiosis-deficient mutant that was able to colonize the host insect but failed to induce normal development of host's symbiotic organ. The disrupted gene was identified as purL involved in purine biosynthesis.