The role of rpoS,hmp, and ssrAB in Salmonella enterica Gallinarum and evaluation of a triple-deletion mutant as a live vaccine candidate in Lohmann layer chickens

Salmonella enterica Gallinarum (SG) causes fowl typhoid (FT), a septicemic disease in avian species. We constructed deletion mutants lacking the stress sigma factor RpoS, the nitric oxide (NO)-detoxifying flavohemoglobin Hmp, and the SsrA/SsrB regulator to confirm the functions of these factors in SG. All gene products were fully functional in wild-type (WT) SG whereas mutants harboring single mutations or a combination of rpoS, hmp, and ssrAB mutations showed hypersusceptibility to H₂O₂, loss of NO metabolism, and absence of Salmonella pathogenicity island (SPI)-2 expression, respectively. A triple-deletion mutant, SGΔ3 (SGΔrpoSΔhmpΔssrAB), was evaluated for attenuated virulence and protection efficacy in two-week-old Lohmann layer chickens. The SGΔ3 mutant did not cause any mortality after inoculation with either 1 × 10⁶ or 1 × 10⁸ colony-forming units (CFUs) of bacteria. Significantly lower numbers of salmonellae were recovered from the liver and spleen of chickens inoculated with the SGΔ3 mutant compared to chickens inoculated with WT SG. Vaccination with the SGΔ3 mutant conferred complete protection against challenge with virulent SG on the chickens comparable to the group vaccinated with a conventional vaccine strain, SG9R. Overall, these results indicate that SGΔ3 could be a promising candidate for a live Salmonella vaccine against FT.     

Effect of histone acetylation modification with sodium butyrate, a histone deacetylase inhibitor, on cell cycle, apoptosis, ploidy and gene expression in porcine fetal fibroblasts

The present study evaluated the effective dose of sodium butyrate (NaB), a histone deacetylase (HDAC) inhibitor, for determination of the level of enhancement of histone acetylation in porcine fetal fibroblasts (PFFs) based on their morphology, growth, apoptosis and cell cycle status. Cells were analyzed for their histone acetylation levels at H3, H4 and H2A and expression of genes related to histone deacetylation (HDAC1, HDAC2 and HDAC3), pro-apoptosis (Bax and Bak) and anti-apoptosis (Bcl-2). PFFs at passage 3-4 were cultured with 0, 0.5, 1.0, 2.0 and 3.0 mM NaB for 96 h. NaB inhibited cell proliferation at all tested concentrations in a dose-dependent manner. However, there was slow cell growth for PFFs treated with 2.0 and 3.0 mM NaB compared with those of untreated PFFs and those treated with other lower concentrations (0.5 and 1.0 mM). More than 85% of the cells that were untreated or treated with 0.5 or 1.0 mM NaB had intact membranes, whereas, approximately 30% of the cells treated with 2.0 or 3.0 mM NaB had increased cell sizes and a more flattened and elongated appearance. NaB induced apoptosis in a dose-dependent manner; the rates of apoptosis were 2.5 +/- 0.4% for 1.0 mM NaB, 7.6 +/- 1.1% for 2.0 mM NaB and 11.2 +/- 1.4% for 3.0 mM NaB. The chromosomal sets of PFFs treated with 0.5 and 1.0 mM NaB were normal, whereas a lower proportion of PFFs treated with 2.0 and 3.0 mM were classified as normal. NaB at 0.5 and 1.0 mM showed little effect on cell cycle. However, 2.0 and 3.0 mM resulted in an increased cell population at the G(0)/G(1) phase. Increased NaB concentrations led to elevated acetylation of H3, H4 and H2A. NaB altered the expression of histone deacetylation and apoptosis-related genes. In conclusion, 1.0 mM NaB induced histone hyperacetylation in the PFFs and produced less deleterious effects than other concentrations; these PFFs might serve as suitable donors for porcine somatic cell nuclear transfer (SCNT).     

Nutrient Losses from a Paddy Field Plot in Central Korea

The study was carried out to investigate the balance and lossesof nutrients at a paddy field plot located at the southwest ofcentral Korea from May 1, 1997 to September 30, 1999. The soilof experimental paddy field was in Jisan series (SiL; fine loamy, mixed mesic family of Fluventic Haplaguepts) and its area was 5,000 m² (100 m × 50 m). The water balance in experimental paddy field was measured as follows.They were 3,693 mm for precipitation, 2,449 mm for irrigationwater, 3,081 mm for runoff water, 1,354 mm for evapotranspitration, and 1,683 mm for infiltration water. Theinput amounts of nitrogen and phosphorus into paddy field weremeasured as follows. They were 155–210 kg N ha^-1 yr^-1 and 30–52 kg P₂O₅ha^-1 yr^-1 by chemical fertilizer, 30–39 kg N ha^-1 yr^-1 and 0.4–0.7 kg P ha^-1 yr^-1 by precipitation, and 22–30 kg N ha^-1 and 0.4–0.5 kg P ha^-1 by irrigationwater, respectively. The output amounts of nitrogen andphosphorus from paddy field were measured as follows. Theywere 107–138 kg N ha^-1 yr^-1 and 3.4–4.6 kg Pha^-1 yr^-1 by runoff water, and 18–20 kg N ha^-1and 0.14–0.16 kg ha^-1 by infiltration water. The runoffloading was the highest in June may be because of the higherconcentrations of chemical components due to applied fertilizer. When the loss ratio of nutrient was calculated based on the amounts of applied chemical fertilizer, the nitrogen and phosphorus by runoff water and infiltration werefound 57.0–65.7% and 8.8–9.4% and 9.7–12.4% and 0.3–0.5%, respectively.     

Antioxidative activity of green tea treated with radical initiator 2, 2'-azobis(2-amidinopropane) dihydrochloride

This study investigated the antioxidative activity of green tea extract, and a green tea tannin mixture and its components, under conditions of radical generation using the hydrophilic azo compound, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to generate peroxyl radicals at a constant and measurable rate in the cultured renal epithelial cell line, LLC-PK(1), which is susceptible to oxidative damage. Treatment with AAPH decreased cell viability and increased the formation of thiobarbituric acid-reactive substances. However, green tea extract, and the tannin mixture and its components, comprising (-)-epigallocatechin 3-O-gallate (EGCg), (-)-gallocatechin 3-O-gallate (GCg), (-)-epicatechin 3-O-gallate (ECg), (-)-epigallocatechin (EGC), (+)-gallocatechin (GC), (-)-epicatechin (EC), and (+)-catechin (C), showed protective activity against AAPH-induced cellular damage. The tannin mixture and its components exhibited higher antioxidative activity than the green tea extract. Furthermore, EGCg and GCg had higher activity than EGC and GC, respectively. In particular, EGCg exerted the most significant cellular protective activity against AAPH. These results indicate that green tea tannin may inhibit cellular loss and lipid peroxidation resulting from the peroxyl radical generated by AAPH, and that the chemical structure of tannin is also involved in the activity, suggesting that the O-dihydroxy structure in the B ring and the galloyl groups are important determinants for radical scavenging and antioxidative potential.     

Root storage of nitrogen applied in autumn and its remobilization to new growth in spring of persimmon trees (Diospyros kaki cv. Fuyu)

This study was conducted to understand the effect of N supply in autumn on its uptake and distribution in tree parts and the utilization of reserve N the following year in persimmon trees (Diospyros kaki cv. Fuyu). The treated trees received 22.5-g N each for two successive years as a 3.5% urea solution from September 18 at 5-day intervals. Trees absorbed about 30% on average of the N applied in autumn. Sixty four to 83% of the N absorbed in autumn was in perennial parts, and 65–72% of that was in roots. Total N in perennial parts of the tree fertilized with N increased by over 4.28 g while leaf N changed little during senescence, indicating that the reserve N was constituted mostly by the N absorbed in autumn. Total N in the new growth was about the same as the amount of N declined in spring from perennial parts, indicating that there was little contribution by soil N to sustain new growth. Total dry weights of new growth the following year in a with-N tree were greater by over 34 g than those in a without-N tree.     

Ligiamycins A and B,Decalin-Amino-Maleimides from the Co-Culture of Streptomyces sp. and Achromobacter sp. Isolated from the Marine Wharf Roach,Ligia exotica

Streptomyces sp. GET02.ST and Achromobacter sp. GET02.AC were isolated together from the gut of the wharf roach, Ligia exotica, inhabiting the intertidal zone of the west coast of Korea. The co-cultivation of these two strains significantly induced the production of two new metabolites, ligiamycins A (1) and B (2), which were barely detected in the single culture of Streptomyces sp. GET02.ST. The planar structures of ligiamycins A (1) and B (2) were elucidated as new decalins coupled with amino-maleimides by the analysis of various spectroscopic data, including nuclear magnetic resonance (NMR), ultraviolet (UV), and mass (MS) data. The assignment of two nitrogen atoms in amino-maleimide in 1 was accomplished based on ¹H-¹⁵N heteroatom single quantum coherence spectroscopy (HSQC) NMR experiments. The relative configurations of the ligiamycins were determined using rotating frame Overhauser effect spectroscopy (ROESY) NMR data, and their absolute configurations were deduced by comparing their experimental and calculated optical rotations. Ligiamycin A (1) displayed antibacterial effects against Staphylococcus aureus and Salmonella enterica, while ligiamycin B (2) exhibited mild cell cytotoxicity against human colorectal cancer cells.     

QTL mapping and effect confirmation for anaerobic germination tolerance derived from the japonica weedy rice landrace PBR

As one of the main rice establishment methods, direct seeding has the advantages of saving labour and reducing costs for farmers. However, the expansion of direct seeding has been constrained by poorly levelled fields, heavy rainfall and poor drainage after sowing. The development of cultivars with anaerobic germination tolerance could improve or overcome these shortcomings of most rice under flooding conditions. In this study, a japonica-type rice with anaerobic germination tolerance was suggested as a new genetic source and QTL analysis was carried out to improve adaptation to direct seeding. Three QTLs, qAG1, qAG3 and qAG11, were identified, explaining 13.44%, 6.71% and 14.52% of the phenotypic variance, respectively. In an evaluation of the most effective QTL combination, two QTL combinations (qAG1^NP + qAG3^PBR + qAG11^PBR and qAG1^NP + qAG11^PBR) showed stable survival rates under submergence of filed condition. Based on the results, we will characterize the candidate genes within the detected target regions in further research, and the lines with advantageous alleles will be used to develop reliable cultivars to support the wide adoption of direct-seeding practices in japonica rice.     

Genotypic and phenotypic characterization of Phytophthora infestans in South Korea during 2009–2016 reveals clonal reproduction and absence of EU_13_A2 genotype

In order to better understand the Phytophthora infestans population structure in South Korea, 172 isolates were collected between 2009 and 2016 from four major potato cultivation areas. Fungicide (metalaxyl and dimethomorph) response, mating type, and microsatellite (SSR) genetic fingerprints were analysed to characterize these isolates. Ten isolates collected in Gyeongnam Province, which specializes in protected winter cultivation in polytunnels, were A2 mating type. All other isolates were A1 mating type. Overall, 42% of the isolates were resistant to metalaxyl, and 43% were sensitive. All isolates were sensitive to dimethomorph. From the SSR fingerprints, 45 distinct genotypes were identified, which could be clustered into four clonal lineages: KR_1_A1, KR_2_A2, SIB-1, and US-11. KR_1_A1 was the predominant P. infestans genotype in South Korea. KR_2_A2 was only found in Gyeongnam Province; all isolates were A2 mating type and resistant to metalaxyl. SIB-1 was dominant until 2013 but its frequency has gradually decreased in more recent years. US-11 was first found in 2014, after which its frequency has increased to become codominant with KR_1_A1. The calculated standardized index of association (I_A) suggests that the South Korean P. infestans population is undergoing clonal reproduction. When compared with populations of P. infestans from the Netherlands, it has less genetic diversity and the dominant Netherlands P. infestans genotype, EU_13_A2 (Blue_13), was not found in South Korea. Such monitoring of the pathogen population contributes to a more efficient integrated pest management-based control strategy for potato late blight control in South Korea.     

Effects of Various Steeping Periods on Physical and Sensory Characteristics of Yukwa (Korean Rice Snack)

This experiment was conducted to investigate the effect of various steeping periods on the physical and sensory properties of yukwa, which is a traditional Korean oil‐puffed snack made of waxy rice, using milled waxy rices (cv. Shinsunchalbyeo) steeped for 0, 1, 3, 6, 9, 12, and 15 days. As the steeping period changed from 0 to 15 days, the cross‐sectional area and expansion ratio of yukwa evaluated by image analysis significantly increased from 226 to 437 mm² and from 805 to 1,874%, respectively. Conversely, the ratio of length to height and density of yukwa significantly decreased with an increase in steeping period duration. The Hunter a value of yukwa tended to increase, whereas b value tended to decrease, as steeping period increased. Among the mechanical textural parameters, hardness was greatly affected by the steeping period range, with values ranging from 1,358 to 25,514 dyne/cm². Sensory results showed that sour aroma, color uniformity, and original flavor tended to increase, but hardness, crispiness, color roughness, oil flavor, and oil aroma tended to decrease in yukwa with the longer steeping period. From these observations, it can be concluded that the steeping period of waxy rice has an influence on the physical and sensory properties of yukwa.