Il Kyu Cho

Development and Assessment of a Liquid Larval Diet for Bactrocera dorsalis (Diptera: Tephritidae)

Abstract Larvae of Bactrocera dorsalis Hendel (Diptera: Tephritidae), the oriental fruit fly, were reared in a liquid diet without mill feed (a biological bulking agent) on a large scale for the first time. Sponge cloth was used as an inert diet-supporting material. Experiments were conducted to identify the rearing components for factory-scale liquid diet rearing based on the larval duration, pupal recovery, pupal weight, adult emergence, flight ability, mating, egg hatch, sex ratio, egg production, and egging duration. The up-to-date recommended rearing conditions using liquid diet are as follows: formula: basic liquid diet includes sugar (8.99%), yeast (15.06%), nipagen (0.15%), sodium benzoate (0.15%), wheat germ oil (0.15%), citric acid (1.70%), and water (73.81%); tray: lid of pupation fiberglass box; seeding egg density: 2.5 ml; diet volume: 1,250 ml; screen: coarse screen or optional depending on the tray design; water quality: tap water; and additives: 0.15% wheat germ oil or higher. Fruit fly performance from larvae reared in this liquid diet is identical to that from conventional mill feed diet, and preliminary tests show that liquid diet technology can be used at the factory scale.

Suitability of a magnetic particle immunoassay for the analysis of PBDEs in Hawaiian euryhaline fish and crabs in comparison with gas chromatography/ electron capture detection-ion trap mass spectrometry

A gas chromatograph/electron capture detector-ion trap mass spectrometer (GC/ECD-ITMS) was used for the determination of polybrominated diphenyl ethers (PBDEs) in euryhaline fish and crabs. GC/ECD-ITMS results showed that average recoveries from the spiked fish samples are in a range of 58-123% with relative standard deviations (RSDs) of 5-19%. PBDE concentrations obtained from GC/ECD-ITMS ranged from 28 ng/g to 1845 ng/g lipid weight (lw) in all aquatic species collected from Hawaiian brackish waters. The general BDE congener concentration profile observed in this study is BDE-47>BDE-100>BDE-154>BDE-99>BDE-153>BDE-28>BDE-183. The ELISA results expressed as BDE-47 equivalents correlated well with those of GC/ECD-ITMS, with a correlation coefficient (R(2)=0.68) and regression coefficient (slope=0.82). Comparison of ELISA with GC/ECD-ITMS results demonstrated that ELISA provides a timely and cost-effective method to screen PBDEs in fish and crab samples.

Application of Multibounce Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy and Chemometrics for Determination of Aspartame in Soft Drinks

Aspartame is a low-calorie sweetener commonly used in soft drinks; however, the maximum usage dose is limited by the U.S. Food and Drug Administration. Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance sampling accessory and partial least-squares regression (PLS) was used for rapid determination of aspartame in soft drinks. On the basis of spectral characterization, the highest R2 value, and lowest PRESS value, the spectral region between 1600 and 1900 cm(-1) was selected for quantitative estimation of aspartame. The potential of FTIR spectroscopy for aspartame quantification was examined and validated by the conventional HPLC method. Using the FTIR method, aspartame contents in four selected carbonated diet soft drinks were found to average from 0.43 to 0.50 mg/mL with prediction errors ranging from 2.4 to 5.7% when compared with HPLC measurements. The developed method also showed a high degree of accuracy because real samples were used for calibration, thus minimizing potential interference errors. The FTIR method developed can be suitably used for routine quality control analysis of aspartame in the beverage-manufacturing sector.

Phn and Nag-like dioxygenases metabolize polycyclic aromatic hydrocarbons in Burkholderia sp. C3

Burkholderia sp. C3 can transform polycyclic aromatic hydrocarbons (PAHs), a class of ubiquitous pollutants, through multiple pathways, indicating existence of multiple dioxygenases (Seo et al., in Biodegradation 18:123–131, 2006a). Both phn and nag-like genes in C3 were cloned and identified with the DNA sequence alignment and the gene organization in the clusters. When cloned and expressed in Escherichia coli, either the alpha- and beta-subunits of dioxygenase of the phn genes or the ferredoxin-, alpha- and beta-subunits of the nag-like genes transformed naphthalene, phenanthrene and dibenzothiophene but at different rates. The E. coli transformant containing the phn genes transformed phenanthrene faster than that containing the nag-like genes, which was consistent with higher transcription of the phnAc gene than the nagAc-like gene in C3 in response to phenanthrene. 1-Hydroxy-2-naphthanoic acid (1H2NA) and 2-hydroxy-1-naphthanoic acid (2H1NA) (3,4- and 1,2-dioxygenation metabolites of phenanthrene, respectively) were detected in the culture medium of the phn genes transformed E. coli. The concentration of 1H2NA was 262-fold higher than 2H1NA in the medium of the phn genes transformed E. coli. The results suggested that the phn genes play a major role in 1,2-/3,4-dioxygenation and 3,4-dioxygenation dominates. Twenty-eight PAH degradation-associated enzymes including those encoded by the nag-like and phn genes in phenanthrene-grown C3 cells were identified via alignment of amino acid sequences of the detected polypeptides with those in protein databases. The polypeptides were determined with nano liquid chromatography–ion trap mass spectrometry after tryptic in-gel digestion of the enzymes on 1D SDS-PAGE.

Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy Coupled with Multivariate Analysis for Measurement of Acesulfame-K in Diet Foods

Fourier transform infrared (FTIR) spectroscopy was investigated as a method for analysis of acesulfame-K content after a simple extraction procedure for certain commercial diet food samples. Partial least squares (PLS) models were developed for prediction of acesulfame-K using select spectral ranges on the basis of relevant IR absorption bands associated with acesulfame-K. The acesulfame-K content of test food samples was predicted accurately in the fingerprint region between 1100 and 1300 cm(-1) with a maximum prediction error of 9.82% when compared with conventional HPLC method. The PLS was found to be a consistently better predictor when both PLS and principal component regression (PCR) analyses were used for quantification of acesulfame-K. The developed procedure was further validated by comparing with HPLC results as well as recovery studies. As a quick tool, the method developed is expected to be used for routine estimation of acesulfame-K in commercial products.

Identification and Classification of Rhizobia by Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry.

Mass spectrometry (MS) has been widely used for specific, sensitive and rapid analysis of proteins and has shown a high potential for bacterial identification and characterization. Type strains of four species of rhizobia and Escherichia coli DH5α were employed as reference bacteria to optimize various parameters for identification and classification of species of rhizobia by matrix-assisted laser desorption/ionization time-of-flight MS (MALDI TOF MS). The parameters optimized included culture medium states (liquid or solid), bacterial growth phases, colony storage temperature and duration, and protein data processing to enhance the bacterial identification resolution, accuracy and reliability. The medium state had little effects on the mass spectra of protein profiles. A suitable sampling time was between the exponential phase and the stationary phase. Consistent protein mass spectral profiles were observed for E. coli colonies pre-grown for 14 days and rhizobia for 21 days at 4°C or 21°C. A dendrogram of 75 rhizobial strains of 4 genera was constructed based on MALDI TOF mass spectra and the topological patterns agreed well with those in the 16S rDNA phylogenetic tree. The potential of developing a mass spectral database for all rhizobia species was assessed with blind samples. The entire process from sample preparation to accurate identification and classification of species required approximately one hour.

Rapid Determination of Sugars in Commercial Fruit Yogurts and Yogurt Drinks Using Fourier Transform Infrared Spectroscopy and Multivariate Analysis

A chemometric study for the quantification of sugars in commercial fruit yogurts and yogurt drink samples was carried out using fourier transform infrared spectrophotometery (FTIR), attenuated total reflectance (ATR), and partial least squares regression (PLS). The calibration set consisted of 43 mixtures of five sugars namely sucrose, glucose, galactose, lactose, and fructose. Different PLS models using raw, first, and second derivative spectra were tested in order to evaluate their prediction ability for the validation set. The second derivative transformation plot over a range of 1500 to 900 cm-1 was found to highlight the variations among sugar mixtures and was further applied onto commercial fruit yogurt and yogurt drink samples for quantification of sugars. Results indicated that FTIR-ATR coupled with multivariate analysis could quantify total sugar contents of commercial fruit yogurts and yogurt drinks within minutes, without the need for any kind of sample preparation.

Diet-induced over-expression of flightless-I protein and its relation to flightlessness in Mediterranean fruit fly, Ceratitis capitata.

The Mediterranean fruit fly (medfly), Ceratitis capitata is among the most economically important pests worldwide. Understanding nutritional requirement helps rearing healthy medfly for biocontrol of its population in fields. Flight ability is a high priority criterion. Two groups of medfly larvae were reared with two identical component diets except one with fatty acids (diet A) and another without it (diet B). Adults from larvae reared on diet B demonstrated 20±8% of normal flight ability, whereas those from larvae reared on diet A displayed full flight ability of 97±1%. Proteomes were profiled to compare two groups of medfly pupae using shotgun proteomics to study dietary effects on flight ability. When proteins detected in pupae A were compared with those in pupae B, 233 and 239 proteins were, respectively, under- and over-expressed in pupae B, while 167 proteins were overlapped in both pupae A and B. Differential protein profiles indicate that nutritional deficiency induced over-expression of flightless-I protein (fli-I) in medfly. All proteins were subjected to Ingenuity Pathway Analysis (IPA) to create 13 biological networks and 17 pathways of interacting protein clusters in human ortholog. Fli-I, leucine-rich repeat (LRR)-containing G protein-coupled receptor 2, LRR protein soc-2 and protein wings apart-like were over-expressed in pupae B. Inositol-1,4,5-trisphosphate receptor, protocadherin-like wing polarity protein stan and several Wnt pathway proteins were under-expressed in pupae B. These results suggest down-regulation of the Wnt/wingless signaling pathway, which consequently may result in flightlessness in pupae B. The fli-I gene is known to be located within the Smith-Magenis syndrome (SMS) region on chromosome 17, and thus, we speculate that nutritional deficiency might induce over-expression of fli-I (or fli-I gene) and be associated with human SMS. However, more evidence would be needed to confirm our speculation.

Characterization and quantification of γ-oryzanol in grains of 16 Korean rice varieties

Abstract γ-Oryzanol, a mixture of ferulic acid esters of triterpene alcohols and sterols, is a nutritionally important group of rice secondary metabolites. A library of 27 γ-oryzanol was assembled from existing data and used to assist identification and quantification of γ-oryzanol isolated from 16 Korean rice varieties (11 white and 5 pigmented). γ-Oryzanol was analyzed with liquid chromatography with diode array detection and electrospray ionization mass spectrometry. Nineteen different γ-oryzanol were observed and identified as stigmasterol, campesterol and sitosterol or common and hydroxylated triterpene alcohols. In the 16 varieties, the total γ-oryzanol content averaged 43.8 mg/100 g (range, 26.7–61.6 mg/100 g), which Josaengheugchal exhibited the highest level (61.6 mg/100 g). The Korean rice varieties were classified based on qualitative and quantitative γ-oryzanol data by multivariate statistical analysis. Clusters of specialty rice varieties exhibited higher γ-oryzanol levels than those of common rice varieties.

Pulmonary Proteome and Protein Networks in Response to the Herbicide Paraquat in Rats.

Paraquat (PQ) has been one of the most widely used herbicides in the world. PQ, when ingested, is toxic to humans and may cause acute respiratory distress syndrome. To investigate molecular perturbation in lung tissues caused by PQ, Sprague Dawley male rats were fed with PQ at a dose of 25 mg/kg body weight for 20 times in four weeks. The effects of PQ on cellular processes and biological pathways were investigated by analyzing proteome in the lung tissues in comparison with the control. Among the detected proteins, 321 and 254 proteins were over-represented and under-represented, respectively, in the PQ-exposed rat lung tissues in comparison with the no PQ control. All over- and under-represented proteins were subjected to Ingenuity Pathway Analysis to create 25 biological networks and 38 pathways of interacting protein clusters. Over-represented proteins were involved in the C-jun-amino-terminal kinase pathway, caveolae-mediated endocytosis signaling, cardiovascular-cancer-respiratory pathway, regulation of clathrin-mediated endocytosis, non-small cell lung cancer signaling, pulmonary hypertension, glutamate receptor, immune response and angiogenesis. Under-represented proteins occurred in the p53 signaling pathway, mitogen-activated protein kinase signaling pathway, cartilage development and angiogenesis inhibition in the PQ-treated lungs. The results suggest that PQ may generate reactive oxygen species, impair the MAPK/p53 signaling pathway, activate angiogenesis and depress apoptosis in the lungs.