Comparative Pathogenicity of Fusarium graminearum Isolates from Wheat Kernels in Korea.

Fusarium head blight (FHB) caused by Fusarium species is a major disease of wheat and barley around the world. FHB causes yield reductions and contamination of grains with trichothecene mycotoxins including; nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), and 15-acetylde-oxynivalenol (15-ADON). The objectives of this study were to identify strains of F. graminearum isolated in Korea from 2012-harvested wheat grain and to test the pathogenicity of these NIV- and DON-producing isolates. Three hundred and four samples of wheat grain, harvested in 2012 in Chungnam, Chungbuk, Gyeongnam, Jeonbuk, Jeonnam, and Gangwon provinces were collected. We recovered 44 isolates from the 304 samples, based on the PCR amplification of internal transcribed spacer (ITS) rRNA region and sequencing. Our findings indicate that F. asiaticum was the predominant (95% of all isolates) species in Korea. We recovered both F. asiaticum and F. graminearum from samples collected in Chungnam province. Of the 44 isolates recovered, 36 isolates had a NIV genotype while 8 isolates belonged to the DON genotype (3-ADON and 15-ADON). In order to characterize the pathogenicity of the strains collected, disease severity was assessed visually on various greenhouse-grown wheat cultivars inoculated using both NIV- and DON-producing isolates. Our results suggest that Korean F. graminearum isolates from wheat belong to F. asiaticum producing NIV, and both F. graminearum and F. asiaticum are not significantly different on virulence in wheat cultivars.

TOPOGRAPHIC CHANGES OF THE MACULA AFTER CLOSURE OF IDIOPATHIC MACULAR HOLE.

PURPOSE: To investigate retinal displacement in the macula after surgical closure of idiopathic macular hole and to identify factors correlated with displacement. METHODS: This retrospective multicenter study included 73 eyes of 73 patients having idiopathic macular hole. A custom program was developed to compare the position of the retinal vessels in the macula between preoperative and postoperative photographs. En face images of a 6 mm × 6 mm optical coherence tomography volume scans were registered to calculate the scale. A grid comprising 16 sectors in 2 rings (inner; 2-4 mm and outer; 4-6 mm) was superimposed. The displacement of the retinal vessels was measured as a vector value by comparing the location of the retinal vessels in each sector. The correlation between displacement and various clinical parameters was analyzed. RESULTS: The average displacement was 57.2 µm at an angle of -3.3° (nasal and slightly inferior). Displacement was larger in the inner ring (79.2 µm) than in the outer ring (35.3 µm, P < 0.001), and larger in the temporal sectors than in the corresponding nasal sectors (P ≤ 0.008). Inferior and superior displacement was noted in the superior and inferior sectors, respectively. Multiple regression analysis revealed that basal horizontal macular hole diameter and size of internal limiting membrane removal were independent factors of displacement. CONCLUSION: The macula was displaced centripetally, nasally, and slightly inferiorly after surgical closure of idiopathic macular hole. Hole closure, contraction of the nerve fiber layer, and gravity are the suggested mechanisms of macular displacement caused by internal limiting membrane peeling.

Intraocular Pharmacokinetics of Povidone-Iodine and Its Effects on Experimental Staphylococcus epidermidis Endophthalmitis.

PURPOSE: The purpose of this study was to investigate the pharmacokinetics and safety of intravitreal povidone-iodine (PVI) and its efficacy against experimental Staphylococcus epidermidis endophthalmitis. METHODS: In phase I, forty New Zealand white rabbits were divided into groups I and II and received intravitreal 0.1% and 0.3% PVI, respectively. Electroretinography (ERG) and histologic examinations were conducted at baseline, 6, and 12 hours. Half-life was determined using high-performance liquid chromatography. In phase II, after the induction of S. epidermidis endophthalmitis, 0.1% and 0.3% PVI were injected intravitreally once in groups A and B and three times every second day in groups C and D (n = 10 in each group). Electroretinographs, histologic examinations, and vitreous cultures were conducted on day 14. RESULTS: Electroretinography and histologic examinations did not reveal any notable retinal damage in phase I in either group. Half-lives were 3.27 and 3.58 hours in groups I and II, respectively. In phase II, all groups demonstrated marked improvement, compared to controls. Bacterial growth was found in four eyes in group A (20, 60, 60, and 70 colony forming units [CFU]) and in three eyes in group B (20, 40, and 60 CFU) but not in those belonging to groups C and D at day 14. Retinal damage with lymphocyte infiltration in the inner retinal layers was more common in groups A and B than in groups C and D. CONCLUSIONS: Half-life of PVI was approximately 3 hours in the vitreous. Repeated injection of intraocular PVI, even at low concentrations, is most likely to be effective for the treatment of bacterial endophthalmitis.

Natural History of Idiopathic Epiretinal Membrane in Eyes with Good Vision Assessed by Spectral-Domain Optical Coherence Tomography.

PURPOSE: To investigate the natural history of idiopathic epiretinal membrane (ERM) in eyes with good visual function using optical coherence tomography (OCT). METHODS: Sixty-two eyes of 58 patients with idiopathic ERM, visual acuity of 20/40 or better, and no significant metamorphopsia were included. The best corrected visual acuity (BCVA), central macular thickness (CMT), membrane configuration, and ellipsoid zone signal data over 24 months were retrospectively analyzed. Based on OCT findings, ERM configurations were categorized as global attachment (GA), partial attachment (PA), pseudohole, and vitreomacular traction (VMT). RESULTS: The mean BCVA and CMT did not change significantly between baseline and 24 months. GA, PA, pseudohole, and VMT types were observed in 33, 19, 9, and 1 eye at baseline, and in 20, 22, 10, and 1 eye at 24 months, respectively. A membrane configuration change was noted in 24 eyes (38.7%) during follow-up, and the distribution shifted from GA to the other types (p < 0.001). Six eyes had visual loss due to membrane progression, and 4 eyes had spontaneous membrane separation. Of the 10 eyes with progression or separation, 6 were of the PA type. CONCLUSIONS: Although the BCVA remains stable over 2 years in most idiopathic ERM eyes with good visual function at baseline, the membrane configuration may change, affecting visual acuity. The GA type would be an early stage, and the PA type is prone to changes in visual acuity.

Changes in Visual Acuity after Idiopathic Epiretinal Membrane Removal: Good versus Poor Preoperative Visual Acuity.

PURPOSE: To investigate postoperative visual acuity changes following idiopathic epiretinal membrane (ERM) surgery as well as investigate the relationship between outcome and baseline visual acuity. METHODS: The medical records of 159 consecutive eyes were retrospectively reviewed for best corrected visual acuity (BCVA), central subfield macular thickness (CSMT), and the ellipsoid zone (EZ) signal of the photoreceptor layer at baseline and 1, 3, and 6 months after surgery. Patients were divided into two groups: group A, with good vision of 20/50 or better, and group B, with poor visual acuity worse than 20/50. RESULTS: Seventy-nine eyes were included in group A and 80 eyes in group B. Mean baseline BCVA was 0.28 and 0.65 logarithm of the minimum angle of resolution (logMAR), and the mean baseline CSMT was 423.7 and 505.6 µm in group A and group B, respectively. In group A, BCVA worsened to 0.39 logMAR at 1 month (p < 0.001) and gradually improved to 0.25 logMAR at 6 months, which was not different from baseline BCVA. In group B, BCVA and CSMT improved at 1, 3, and 6 months (p < 0.05). The EZ signal improved in group B (p = 0.003) but not in group A. The area under the receiver operating characteristic curve for the improvement in BCVA of ≥ 2 lines was significant for preoperative BCVA (0.717, 95% confidence interval 0.638-0.797; p < 0.001). The cutoff value was 0.35 on the logMAR scale. CONCLUSION: After ERM surgery, patients with good vision maintained visual acuity after temporary worsening of vision, and patients with poor vision achieved significant BCVA improvement.

Sphingomonas lacus sp. nov., an astaxanthin-dideoxyglycoside-producing species isolated from soil near a pond.

Taxonomic studies were performed on an astaxanthin-dideoxyglycoside-producing strain, designated PB304(T), isolated from soil near a pond in Daejeon city, South Korea. Cells of strain PB304(T) were Gram-staining-negative, strictly aerobic, orange-coloured and motile, and occurred as single or paired short chains. PB304(T) did not contain bacteriochlorophyll a. 16S rRNA gene sequence analysis revealed that strain PB304(T) was closely related to 'Sphingomonas humi' KCTC 12341 (98.7%), Sphingomonas kaistensis KCTC 12344(T)(97.9%), Sphingomonas astaxanthinifaciens DSM 22298(T) (97.6%) and Sphingomonas ginsengisoli KCTC 12630(T) (97.5%). Analysis of pufLM gene sequences revealed strain PB304(T) to be closely related to 'S. humi' KCTC 12341 (88.1%). The major cellular fatty acids were C16 : 0, summed feature 4 (comprising iso-C15 : 0 2-OH and/or C16 : 1ω7c), and summed feature 7 (comprising C18  : 1ω7c/ω9t/ω12t). Ubiquinone 10 (Q-10) was the sole quinone identified, and the major pigment was astaxanthin dideoxyglycoside. The major polar lipids were sphingoglycolipid, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The polyamine was spermidine. The DNA-DNA relatedness values of strain PB304(T) with respect to its closest phylogenetic neighbours were 57.1% for 'S. humi' KCTC 12341, 51.2% for Sphingomonas kaistensis KCTC 12334T, 50.6% for Sphingomonas astaxanthinifaciens DSM 22298(T) and 50.2% for Sphingomonas ginsengisoli KCTC 12630(T). The DNA G+C content of strain PB304(T) was 66.6 mol%. On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain PB304T is concluded to represent a novel species of the genus Sphingomonas, for which the name Sphingomonas lacus is proposed. The type strain is PB304(T) ( = KCTC 32458(T) = CECT 8383(T)).

Microbial ecology of watery kimchi.

The biochemistry and microbial ecology of 2 similar types of watery (mul) kimchi, containing sliced and unsliced radish and vegetables (nabak and dongchimi, respectively), were investigated. Samples from kimchi were fermented at 4, 10, and 20 °C were analyzed by plating on differential and selective media, high-performance liquid chromatography, and high-throughput DNA sequencing of 16S rDNA. Nabak kimchi showed similar trends as dongchimi, with increasing lactic and acetic acids and decreasing pH for each temperature, but differences in microbiota were apparent. Interestingly, bacteria from the Proteobacterium phylum, including Enterobacteriaceae, decreased more rapidly during fermentation at 4 °C in nabak cabbage fermentations compared with dongchimi. Although changes for Proteobacterium and Enterobacteriaceae populations were similar during fermentation at 10 and 20 °C, the homolactic stage of fermentation did not develop for the 4 and 10 °C samples of both nabak and dongchimi during the experiment. These data show the differences in biochemistry and microbial ecology that can result from preparation method and fermentation conditions of the kimchi, which may impact safety (Enterobacteriaceae populations may include pathogenic bacteria) and quality (homolactic fermentation can be undesirable, if too much acid is produced) of the product. In addition, the data also illustrate the need for improved methods for identifying and differentiating closely related lactic acid bacteria species using high-throughput sequencing methods.

Phytoremediation of Heavy Metals in Contaminated Water and Soil Using Miscanthus sp. Goedae-Uksae 1.

The aim of this study is to characterize the heavy metal phytoremediation potential of Miscanthus sp. Goedae-Uksae 1, a hybrid, perennial, bio-energy crop developed in South Korea. Six different metals (As, Cu, Pb, Ni, Cd, and Zn) were used for the study. The hybrid grass effectively absorbed all the metals from contaminated soil. The maximum removal was observed for As (97.7%), and minimum removal was observed for Zn (42.9%). Similarly, Goedae-Uksae 1 absorbed all the metals from contaminated water except As. Cd, Pb, and Zn were completely (100%) removed from contaminated water samples. Generally, the concentration of metals in roots was several folds higher than in shoots. Initial concentration of metals highly influenced the phytoremediation rate. The results of the bioconcentration factor, translocation factor, and enrichment coefficient tests indicate that Goedae-Uksae 1 could be used for phytoremediation in a marginally contaminated ecosystem.