• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.301-311
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• 2015

To enhance Bacillus thuringiensis (Bt) efficacy, four Cry toxins were purified from four different Bt strains and assessed in their combined efficacy. The Cry mixtures significantly expanded their target insect spectra. Bacterial culture broth of Xenorhabdus nematophila (Xn) significantly suppressed insect cellular immune response and increased Cry toxicity. The addition of Xn culture broth to Cry mixture significantly enhanced Bt efficacy in target insect spectrum and insecticidal activity.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.10a
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• pp.85-86
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• 2003

Apolipophorin III (apoLp-III) is a protypical exchangeable apolipoprotein that is abundant in hemolymph of many insect species. Its function lies in the stabilization of low-density lipophorin particles (LDLp) crossing the hemocoel in phases of high energy consumption to deliver lipids from the fat body to the flight muscle cells. But, recent studies with naive Galleria mellonella-apoLp-III gave first indications of an unexpected role of that protein in insect immune activation (Niere et al., 1999). (omitted)

• Korean journal of applied entomology
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• v.51 no.3
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• pp.245-253
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• 2012

Benzylinedeneacetone (BZA) is a bacterial metabolite which is synthesized by at least two entomopathogenic bacteria, namely Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata. It has been shown to possess inhibitory effects on insect cellular and humoral immune responses as well as antimicrobial activities against various species of bacteria and fungi. However, its relatively high phytotoxicity, and nonsystematic effect have thus far prevented its development into an optimal pesticide. This study screened five different BZA derivatives in order to select an optimal compound, which would have relatively high solubility and low phytotoxicity while retaining sufficient degrees of the immunosuppressive and antimicrobial activities associated with BZA. Hydroxylation of the benzene ring of BZA was found to significantly suppress its immunosuppressive and antimicrobial activities. Transformation of the ketone of BZA by carboxylation also suppressed the inhibitory activities. However, a shortening of the aliphatic chain of BZA into acetate form (4-hydroxyphenylacetic acid: HPA) did not decrease the inhibitory activity. HPA also showed much less phytotoxicity against the hot pepper plant Capsicum annuum, when compared to BZA. This study identified an optimal BZA derivative, which exhibited relatively little phytotoxicity, but retained a high degree of inhibitory activity to suppress insect immune responses and antimicrobial activities against plant pathogens.

• Journal of Life Science
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• v.25 no.6
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• pp.715-723
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• 2015

Insects represent the largest class within the animal kingdom in terms of species number. Humans had been utilized insect in the broad area, including food, agriculture, industry, pharmaceuticals and so on. At present, insects are emerging as a leading group for identifying and extracting novel bioactive substances due to enormous number and a high nutritional value. Insects rely on a suite of systemic response to resist infection such as immune cells, hemocytes, activation of enzymes cascades, and antimicrobial peptide/protein. Among the substances, antimicrobial peptides (AMPs) are main components of potent antimircrobial innate defense system into the insect hemolymph. AMPs raise influential candidate as avenue to resolve the development of antibiotic-resistant microbial organism. Insect AMPs are classified into four main classes: cecropins, insect defensins, glycine/proline-rich peptides. Insect AMPs have been purified, over 150. In this review, AMPs derived from several insects were summarized including honey bee, dung beetle, butterfly and longicorn beetle. These peptides almost exhibited potent antimicrobial activities against human microbial pathogens without causing remarkable hemolysis to erythrocytes excluding melittin, and their mode of action(s) are based on disruption of the plasma membrane or fungal apoptosis. Therefore, study of insect AMPs is expected to be useful for designing novel therapeutic antimicrobial applications.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.173-195
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• 2022

Like vertebrates, insects synthesize various eicosanoids after the committed catalytic step of phospholipase A₂ (PLA₂). However, the subsequent biosynthetic steps exhibit some deviation from those of vertebrates. Due to little composition of arachidonic acid in insect phospholipids, PLA₂ releases linoleic acid, which is another polyunsaturated fatty acid and relatively rich in insect phospholipids, to synthesize arachidonic acid via chain extension and desaturation. Resulting arachidonic acid is then oxygenated into a prostaglandin (PG), PGH₂, by a specific peroxidase called peroxynectin, but not by cyclooxygenase. PGH₂ is then isomerized to various PGs such as PGA₂, PGD₂, PGE₂, PGI₂, and a thromboxane (TXB₂). All four epoxyeicosatrienoic acids such as 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET are also synthesized from arachidonic acid by oxygenation of vertebrate types of monooxygenases. However, the other type of eicosanoids called leukotrienes are found in insect tissues but their synthetic pathway is unclear. Eicosanoids mediate various insect physiological processes such as metabolism, excretion, immunity, and reproduction. Thus, identification of novel compounds interrupting eicosanoid biosynthesis would be a novel approach to develop insecticides. This review focuses on PGs and their immune mediation.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.2
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• pp.85-91
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• 2016

Exosomes are homogenous vesicles of 40-100 nm diameter produced endogenously. Exosomes are generated by inward budding into multi-vesicular bodies (MVB) and then released to extracellular space. Exosomes contain various nucleic acid and protein cargoes from their cells of origin and this endosomal cellular molecules are used for intracellular communication and for both promotion and suppression of immune responses. Recently, they are also considered as delivery vehicle for therapeutic proteins due to their characteristics of stability in body fluids and ability for target uptake. Also, they show less immune reactivity because the isolated exosome harboring therapeutic proteins can be from the same host. White-spotted flower chafer, Protaetia brevitarsis is one of the major insect commercially reared in Korea. There are bacterial and fungal pathogens causing diseases in the beetle, and these diseases incur economic loss to the larva-rearing farms. Due to their endosomal cargoes, exosomes are good candidates in use of disease diagnosis. In this study, we isolated insect exosome from the hemolymph of P. brevitarsis, and verified it by analysis of the exosome-specific surface proteins and RNA.

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.95-99
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• 2018

In insect defense system, antimicrobial peptides (AMPs) are one of important biological molecules to survive in a variety of environments. Insect can synthesize AMPs to protect against invading pathogens in humoral immune response. Taking more advantage of biological antimicrobial molecules, we report antibacterial activity of two cecropin type peptides, cecropin and moricin, isolated from the silkworm against four salmonella species. In this work, we purified antimicrobial candidate peptides (AMCP) from the extracts of immune challenged silkworm larval hemolymph by two-step chromatographic purification procedure, cation exchange and gel permeation chromatography. The molecular weights of purified peptides were estimated to be about 4 ~ 5 kDa by Tricin SDS-PAGE analysis, and identified as silkworm cecropin and moricin by NCBI BLAST homology search with their N-terminal amino acid sequences. As antibacterial activity assay, the purified peptides showed stronger antibacterial activity against Salmonella pathogens with an MIC value of $1{\sim}4{\mu}g/mL$. Therefore two cecropin type peptides purified from the silkworm will be valuable potential materials for development of new natural antibiotics.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.97-108
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• 2005

Samples of water, soil, and sediment were taken from 10 streams near Andong, Korea in May 2004. To assess the degree of environmental pollution of each stream, chemical pollutants such as total notrogen (T-N), total phosphorus (T-P), chemical oxygen demand (COD), heavy metals, organophosphorus pesticides, organochlorine pesticides, and dioxin-like PCB congeners were analyzed by standard process tests or U.S. EPA methods. In addition, biomarkers originated from insect immune systems of beet armyworm, Spodoptera exigua, were used to analysis of the environmental samples. Except Waya-chun stream showing T-N content of 9.12 mg/L, most streams were contaminated with relatively low levels of overall pollutants in terms of T-N, T-P, and COD, compared to their acceptable environmental levels designated by the Ministry of Environment. Contents of Pb and Cd in samples of each stream were much lower than environmentally permissible levels. However, several times higherconcentrations of Pb and Cd were found in locations at Mi-chun, Kilan-chun, and Hyunha-chun streams, in comparison with other streams. Diazinon, parathion, and phenthoate compounds among organophosphorus pesticides were detected as concentrations of 0.19, 0.40, and $1.13\;{\mu}g/g$, respectively, from soil sample collected in the vicinity of Mi-chun stream. On the other hand, 16 organochlorine pesticides and 12 dioxin-like PCB congeners, known as endocrine disrupting chemicals, selected in this study were not found above the limit of detection. Biomarker analyses using insect immune responses indicated that Waya-chun stream was suspected as exposure to environmental pollutants. Limitation and compensation of both environmental analysis techniques are discussed.

• Journal of Plant Biology
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• v.6 no.2
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• pp.9-21
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• 1963

A mosaic diseased radish collected from the suburb of Seoul, in November, 1961 was used for studing the host range, physical properteis, purificaitiion, insect transmission, and electron microscopy. A Japanese strain of radish mosaic(RPV) was also used with Korean strain of radish mosaic (KRMV) for a comparative study. The two viruses, KRMA and RPV, were identified by the difference in host range, insect transmission and electron microscopy. The KRMA was severely infective on tobacco and Nicotiana glutinosa, while on Gomphrena globsa was immune to the virus. RPV produces necrotic local lesions on Gomphrena globosa but did not infect tobacco and N. glutinosa. Among varieties of radish, Seoul, Akamaroo, Akanagea, Koong-Joong showed more severe symptoms than Simoo, Minong, Paek-soo, which appeared to be fainly resistant. In a number of tests, it was found that the virus KRMA retained its infectivity until to a dilution of 1:2,000, heating at $58^{\circ}$ for 10 minutes, adn aging in vitro for 7 days at room temperature. The RPV was not inactivated until it was diluted to 1:2,000, heated to $56^{\circ}$, and aged for 6 days. The KRMV was readily transmitted by the aphid(Myzus persicae Sulz). The virus RPV was not transmitted by the aphid in a number of tests. Partialy purified viruses using ammonium acetate buffer, salting-out by ammonium sulfate and centrifugation of high and low speed were highly infective. Electron micrographs showed that the KRMV paticles are of spherical particles whereas the RPV particles are rod-shaped.

• Journal of Plant Biology
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• v.6 no.2
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• pp.7-7
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• 1963

A mosaic diseased radish collected from the suburb of Seoul, in November, 1961 was used for studing the host range, physical properteis, purificaitiion, insect transmission, and electron microscopy. A Japanese strain of radish mosaic(RPV) was also used with Korean strain of radish mosaic (KRMV) for a comparative study. The two viruses, KRMA and RPV, were identified by the difference in host range, insect transmission and electron microscopy. The KRMA was severely infective on tobacco and Nicotiana glutinosa, while on Gomphrena globsa was immune to the virus. RPV produces necrotic local lesions on Gomphrena globosa but did not infect tobacco and N. glutinosa. Among varieties of radish, Seoul, Akamaroo, Akanagea, Koong-Joong showed more severe symptoms than Simoo, Minong, Paek-soo, which appeared to be fainly resistant. In a number of tests, it was found that the virus KRMA retained its infectivity until to a dilution of 1:2,000, heating at $58^{\circ}$ for 10 minutes, adn aging in vitro for 7 days at room temperature. The RPV was not inactivated until it was diluted to 1:2,000, heated to $56^{\circ}$, and aged for 6 days. The KRMV was readily transmitted by the aphid(Myzus persicae Sulz). The virus RPV was not transmitted by the aphid in a number of tests. Partialy purified viruses using ammonium acetate buffer, salting-out by ammonium sulfate and centrifugation of high and low speed were highly infective. Electron micrographs showed that the KRMV paticles are of spherical particles whereas the RPV particles are rod-shaped.