The antibacterial activity of immune-related peptides, identified by a differential gene
expression analysis, was investigated to suggest novel antibacterial peptides. A cDNA encoding a defensin-like peptide, Coprisin, was isolated from bacteria-immunized dung beetle, Copris tripartitus, by using differential dot blot hybridization. Northern blot
analysis showed that Coprisin mRNA was up-regulated from 4 hours after bacteria injection and its expression level was reached a peak at 16 hours. The deduced amino acid sequence of Coprisin was composed of 80 amino acids with a predicted molecular weight of 8.6 kDa and a pI of 8.7. The amino acid sequence of mature Coprisin was found to be 79.1% and 67.4% identical to those of defensin-like peptides of Anomala cuprea and Allomyrina dichotoma, respectively. We also investigated active sequences of Coprisin by using amino acid modification. The result showed that the 9-mer peptide, LLCIALRKK-NH2, exhibited potent antibacterial activities against Escherichia coli and Staphylococcus aureus.
Defensins, which are small cationic molecules produced by organisms as part of their innate immune response, share a common structural scaffold that is stabilized by three disulfide bridges. Coprisin is a 43-amino acid defensin-like peptide from Copris tripartitus. Here, we report the intramolecular disulfide connectivity of cysteine-rich coprisin, and show that it is the same as in other insect defensins. The disulfide bond pairings of coprisin were determined by combining the enzymatic cleavage and mass analysis. We found that the loss of any single disulfide bond in coprisin eliminated all antibacterial, but not antifungal, activity. Circular dichroism (CD) analysis showed that two disulfide bonds, Cys20-Cys39 and Cys24-Cys41, stabilize coprisin’s α-helical region. Moreover, a BLAST search against UniProtKB database revealed that coprisin’s α-helical region is highly homologous to those of other insect defensins. [BMB Reports 2014; 47(11): 625-630]
Antimicrobial peptide; Circular dichroism; Coprisin; disulfide connectivity; Insect defensin
Neutrophils play an important role in the initiation of innate immunity against infection and injury. Although many different types of G-protein coupled receptors are functionally expressed in neutrophils, no reports have demonstrated functional expression of umami taste receptor in these cells. We observed that mouse neutrophils express the umami taste receptor T1R1/T1R3 through RNA sequencing and quantitative RT-PCR analysis. Stimulation of mouse neutrophils with L-alanine or L-serine, which are ligands for the umami taste receptor, elicited not only ERK or p38 MAPK phosphorylation but also chemotactic migration. Moreover, addition of L-alanine or L-serine markedly reduced the production of several cytokines including TNF-α induced by lipopolysaccharide (LPS) through inhibition of NF-κB activity or STAT3 phosphorylation in neutrophils. Our findings demonstrate that neutrophils express the umami taste receptor, through which tastants stimulate neutrophils, resulting in chemotactic migration, and attenuation of LPS-induced inflammatory response. [BMB Reports 2014; 47(11): 649-654]
Chemotaxis; Cytokine; Inflammation; Neutrophil; Umami taste receptor T1R1/T1R3
NADH:quinone oxidoreductase 1 (NQO1) is known to be involved in the regulation of energy synthesis and metabolism, and the functional studies of NQO1 have largely focused on metabolic disorders. Here, we show for the first time that compared to NQO1-WT mice, NQO1-KO mice exhibited a marked increase of permeability and spontaneous inflammation in the gut. In the DSS-induced colitis model, NQO1-KO mice showed more severe inflammatory responses than NQO1-WT mice. Interestingly, the transcript levels of claudin and occludin, the major tight junction molecules of gut epithelial cells, were significantly decreased in NQO1-KO mice. The colons of NQO1-KO mice also showed high levels of reactive oxygen species (ROS) and histone deacetylase (HDAC) activity, which are known to affect transcriptional regulation. Taken together, these novel findings indicate that NQO1 contributes to the barrier function of gut epithelial cells by regulating the transcription of tight junction molecules. [BMB Reports 2014;47(9): 494-499]
Barrier dysfunction of epithelial cells; Chromosome condensation; Claudin-1; Gut epithelial cell tight junction; Gut inflammation; Histone acetylation/deacetylation; NQO1 knockout mice; Occludin; Transcription
The larval form of Tenebrio molitor (T. molitor) has been eaten in many countries and provides benefits as a new food source of protein for humans. However, no information exists regarding its safety for humans. The objective of the present study was to evaluate the genotoxicity and repeated dose oral toxicity of the freeze-dried powder of T. molitor larvae. The genotoxic potential was evaluated by a standard battery testing: bacterial reverse mutation test, in vitro chromosome aberration test, and in vivo micronucleus test. To assess the repeated dose toxicity, the powder was administered once daily by oral gavage to Sprague-Dawley (SD) rats at dose levels of 0, 300, 1000 and 3000 mg/kg/day for 28 days. The parameters which were applied to the study were mortality, clinical signs, body and organ weights, food consumption, ophthalmology, urinalysis, hematology, serum chemistry, gross findings and histopathologic examination. The freezedried powder of T. molitor larvae was not mutagenic or clastogenic based on results of in vitro and in vivo genotoxicity assays. Furthermore, no treatment-related changes or findings were observed in any parameters in rats after 28 days oral administration. In conclusion, the freeze-dried powder of T. molitor larvae was considered to be non-genotoxic and the NOAEL (No Observed Adverse Effect Level) was determined to be 3000 mg/kg/day in both sexes of SD rats under our experimental conditions.
Edible insect; Genotoxicity; Repeated dose toxicity; Tenebrio molitor larvae
The anti-inflammatory effects of glycosaminoglycan (GAG) derived from Isaria sinclairii (IS) and of IS extracts were investigated in a complete Freund’s adjuvant (CFA)-treated chronic arthritis rat model. Groups of rats were treated orally with 30 mg/kg one of the following:  saline control, extracts of  water-IS,  methanol-IS,  butanol-IS,  ethyl acetate-IS, or  Indomethacin® as the positive control for a period of two weeks. The anti-paw edema effects of the individual extracts were in the following order: water-IS ex. > methanol ex. > butanol ex. > ethyl acetate ex. The water/methanol extract from I. sinclairii remarkably inhibited UV-mediated upregulation of NF-κB activity in transfected HaCaT cells. GAG as a water-soluble alcohol precipitated fraction also produced a noticeable anti-edema effect. This GAG also inhibited the pro-inflammatory cytokine levels of prostaglandin E2-stimulated lipopolysaccharide in LAW 264.7 cells, cytokine TNF-α production in splenocytes, and atherogenesis cytokine levels of vascular endothelial growth factor (VEGF) production in HUVEC cells in a dose-dependent manner. In the histological analysis, the LV dorsal root ganglion, including the articular cartilage, and linked to the paw-treated IS GAG, was repaired against CFA-induced cartilage destruction. Combined treatment with Indomethacin® (5 mg/kg) and IS GAG (10 mg/kg) also more effectively inhibited CFA-induced paw edema at 3 hr, 24 hr, and 48 hr to levels comparable to the anti-inflammatory drug, indomethacin. Thus, the IS GAG described here holds great promise as an anti-inflammatory drug in the future.
Isaria sinclairii; Glycosaminoglycan; Inflammation
A total of 48 different volatile oils were identified form P. brevitarsis larvae by gas chromatography/mass spectrometry (GC/MS). Acids (48.67%) were detected as the major group in P. brevitarsis larvae comprising the largest proportion of the volatile compounds, followed by esters (19.84%), hydrocarbons (18.90%), alcohols (8.37%), miscellaneous (1.71%), aldehydes (1.35%) and terpenes (1.16%). The major volatile constituents were 9-hexadecenoic acid (16.75%), 6-octadecenoic acid (14.88%) and n-hexadecanoic acid (11.06%). The composition of fatty acid was also determined by GC analysis and 16 fatty acids were identified. The predominant fatty acids were oleic acid (C18:1, 64.24%) followed by palmitic acid (C16:0, 15.89%), palmitoleic acid (C16:1, 10.43%) and linoleic acid (C18:2, 4.69%) constituting more than 95% of total fatty acids. The distinguished characteristic of the fatty acid profile of P. brevitarsis larvae was the high proportion of unsaturated fatty acid (80.54% of total fatty acids) versus saturated fatty acids (19.46% of total fatty acids). Furthermore, small but significant amounts of linoleic, linolenic and γ-linolenic acids bestow P. brevitarsis larvae with considerable nutritional value. The novel findings of the present study provide a scientific basis for the comprehensive utilization of the insect as a nutritionally promising food source and a possibility for more effective utilization.
Protaetia brevitarsis; fatty acid; volatile oil; simultaneous distillation extraction (SDE); GC; GC/MS
In this study, we prepared alcohol extracts of the larva, pupa, queen, and cocoon (clony) of B. ignitus, B. terrestris, and B. h. sapporoensis, and tested the anti-inflammatory activity of the extracts by using a rat model of adjuvant-induced edema. The extracts derived from the queen of B. ignitus, the queen of B. terrestris, and the cocoon of B. ignitus decreased hind paw edema after 1 day of i.p. administration. These extracts also induced vasorelaxation and NO production in calf pulmonary artery endothelial cells. These results suggest that bumblebee alcohol extracts has anti-inflammatory and vasorelaxant properties.
Edema; Bumblebee alcohol extract
Thirty-two different volatile oils were identified from Allomyrina dichotoma (A. dichotoma) larvae by gas chromatography/mass spectrometry (GC/MS). The major volatile components were 2,2,4-trimethyl-3-carboxyisopropyl pentanoic acid isobutyl ester (5.83%), phenol,2,6-bis(a,a-dimethyl ethyl)-4-(1-methyl-1-phenylethyl) (5.72%), heptacosane (5.49%) and phenol,2,4-bis(1-methyl-1-phenylethyl) (5.47%). The composition of the fatty acids in A. dichotoma larvae was also determined by gas chromatography (GC) and fourteen constituents were identified. Oleic acid (19.13%) was the most abundant fatty acid followed by palmitic acid (12.52%), palmitoleic acid (3.71%) and linoleic acid (2.08%) in 100 g of A. dichotoma larvae on a dry weight basis. The quantity of unsaturated fatty acids (64.00%) were higher than that of saturated ones (36.00%). The predominant fatty acids in A. dichotoma consist of monounsaturated fatty acid (MUFA, 57.70%) such as oleic acid, myristoleic acid and palmitoleic acid, followed by saturated fatty acids (36.00%) and polyunsaturated fatty acids (PUFA, 6.50%). In particular, the presence of essential fatty acids, such as linoleic (5.30%) and linolenic acid (0.40%) give A. dichotoma larvae considerable nutritional and functional value and it may be a useful source for food and/or industrial utilization.
Allomyrina dichotoma; fatty acids; GC; GC/MS; SDE; volatile oils
Clostridium difficile-associated diarrhea and pseudomembranous colitis are typically treated with vancomycin or metronidazole, but recent increases in relapse incidence and the emergence of drug-resistant strains of C. difficile indicate the need for new antibiotics. We previously isolated coprisin, an antibacterial peptide from Copris tripartitus, a Korean dung beetle, and identified a nine-amino-acid peptide in the α-helical region of it (LLCIALRKK) that had antimicrobial activity (J.-S. Hwang et al., Int. J. Pept., 2009, doi:10.1155/2009/136284). Here, we examined whether treatment with a coprisin analogue (a disulfide dimer of the nine peptides) prevented inflammation and mucosal damage in a mouse model of acute gut inflammation established by administration of antibiotics followed by C. difficile infection. In this model, coprisin treatment significantly ameliorated body weight decreases, improved the survival rate, and decreased mucosal damage and proinflammatory cytokine production. In contrast, the coprisin analogue had no apparent antibiotic activity against commensal bacteria, including Lactobacillus and Bifidobacterium, which are known to inhibit the colonization of C. difficile. The exposure of C. difficile to the coprisin analogue caused a marked increase in nuclear propidium iodide (PI) staining, indicating membrane damage; the staining levels were similar to those seen with bacteria treated with a positive control for membrane disruption (EDTA). In contrast, coprisin analogue treatment did not trigger increases in the nuclear PI staining of Bifidobacterium thermophilum. This observation suggests that the antibiotic activity of the coprisin analogue may occur through specific membrane disruption of C. difficile. Thus, these results indicate that the coprisin analogue may prove useful as a therapeutic agent for C. difficile infection-associated inflammatory diarrhea and pseudomembranous colitis.
Gryllus bimaculatus (Gb) was orally administered at doses of 0, 0.04, 0.2, 1 and 5 g/kg bw/day for 13 consecutive weeks. There were no observed clinical signs or deaths related to treatment in all the groups tested. Therefore, the approximate lethal oral dose of G. bimaculatus was considered to be higher than 5 g/kg in rats. Throughout the administration period, no significant changes in diet consumption, ophthalmologic findings, organ weight, clinical pathology (hematology, clinical chemistry, coagulation, and urinalysis) or gross pathology were detected. Minor changes were found in hematological parameters for the 5 g/kg Gb-treated group (triglyceride reduction of 35.8%), but all changes were within normal physiological ranges. Microscopic examination did not identify any treatment-related histopathologic changes in the organs of Gb-treated rats in the high dose group. From these results, one can conclude that the no-observed adverse effect level (NOAEL) of G. bimaculatus is higher than 5 g/kg bw/day in rats.
G. bimaculatus; 13-Week toxicity
Isaria sinclairii (Cicada Dongchunghacho) was studied as a potential crude natural food in powdered form. The role of tissue fatty acids in relation to the anti-obesity effects of I. sinclairii (IS) was examined by feeding the powder to SD rats ad libitum at 0, 1.25, 2.5, 5 and 10% (calculated about 8 g/kg) of the feed for a period of 3 months and 6 months. The fatty acid composition profile as indicated GC-MS, showed significantly slight dose-dependent increases in the levels of unsaturated fatty acids, particularly, arachidonic acid (C20: 4n6) , oleic acid, linoleic acid, eicosadienoic acid, eicosapentaenoic acid (EPA) (C20: 5) concentration in the the ad libitum IS-fed groups compared to the control group in SD abdominal fat over 6 month period. Over viewing of the SD and Ob mice treated Isaria sinclairii powder; there were increases in the single (mono) unsaturated fatty acids ratio but decreases in polyunsaturated fatty acid. In IS-fed groups in proportion to the treatment period, this Dongchunghacho also induced an increase in the level of same result of unsaturated fatty acid in C57BL/6 obese (ob/ob) mice over a 6-month period treatment compared to those given 10% dry mulberry leaf powder (ML) or silkworm powder mixed with the standard diet.
Anti-diabetic effect; Isaria sinclairii; Obese mice; 6 months treatment
We have isolated a complementary deoxyribonucleic acid clone that encodes the protein disulfide isomerase of Bombyx mori (bPDI). This protein has a putative open reading frame of 494 amino acids and a predicted size of 55.6 kDa. In addition, 2 thioredoxin active sites, each with a CGHC sequence, and an endoplasmic reticulum (ER) retention signal site with a KDEL motif were found at the C-terminal. Both sites are typically found in members of the PDI family of proteins. The expression of bPDI messenger ribonucleic acid (mRNA) was markedly increased during ER stress induced by stimulation with calcium ionophore A23187, tunicamycin, and dithiothreitol, all of which are known to cause an accumulation of unfolded proteins in the ER. We also examined the tissue distribution of bPDI mRNA and found pronounced expression in the fat body of insects. Hormonal regulation studies showed that juvenile hormone, insulin, and a combination of juvenile hormone and transferrin (although not transferrin alone) affected bPDI mRNA expression. A challenge with exogenous bacteria also affected expression, and the effect peaked 16 hours after infection. These results suggest that bPDI is a member of the ER-stress protein group, that it may play an important role in exogenous bacterial infection of the fat body, and that its expression is hormone regulated.