qPCR-Based Monitoring of 2-Methylisoborneol/Geosmin-Producing Cyanobacteria in Drinking Water Reservoirs in South Korea.

Cyanobacteria can exist in water resources and produce odorants. 2-Methylisoborneol (2-MIB) and geosmin are the main odorant compounds affecting the drinking water quality in reservoirs. In this study, encoding genes 2-MIB (mic, monoterpene cyclase) and geosmin (geo, putative geosmin synthase) were investigated using newly developed primers for quantitative PCR (qPCR). Gene copy numbers were compared to 2-MIB/geosmin concentrations and cyanobacterial cell abundance. Samples were collected between July and October 2020, from four drinking water sites in South Korea. The results showed similar trends in three parameters, although the changes in the 2-MIB/geosmin concentrations followed the changes in the mic/geo copy numbers more closely than the cyanobacterial cell abundances. The number of odorant gene copies decreased from upstream to downstream. Regression analysis revealed a strong positive linear correlation between gene copy number and odorant concentration for mic (R2 = 0.8478) and geo (R2 = 0.601). In the analysis of several environmental parameters, only water temperature was positively correlated with both mic and geo. Our results demonstrated the feasibility of monitoring 2-MIB/geosmin occurrence using qPCR of their respective synthase genes. Odorant-producing, gene-based qPCR monitoring studies may contribute to improving drinking water quality management.

Characteristics, Possible Origins, and Health Risk Assessment of Trace Elements in Surface Waters of the Han River Watershed, South Korea.

To safeguard aquatic environments in and around the Han River watershed in South Korea, a multivariate statistical evaluation of trace elements, a trace element concentration analysis and source determination, and a human health risk assessment were conducted on 10 trace elements at 25 sites. The results demonstrated that the Han River watershed was mainly affected by anthropogenic activities (traffic/industrial activity). The range of concentrations was arranged in descending order: Fe (217.13 ± 301.03 µg/L) > Mn (102.36 ± 153.04 µg/L) > Zn (23.33 ± 79.63 µg/L) > Ba (29.05 ± 12.37 µg/L) > Ni (5.14 ± 11.57 µg/L) > Cu (3.80 ± 3.56 µg/L) > Pb (0.46 ± 0.52 µg/L) > Se (0.06 ± 0.04 µg/L) > Cd (0.01 ± 0.01 µg/L) > Ag (0.004 ± 0.013 µg/L). The hazard index values of trace elements in surface water for combined pathways (ingestion and dermal contact) were < 1.0 for both adults and children, indicating no possible human health hazards. The estimated total cancer risk did not exceed the acceptable limit (1 × 10-4) for adults and children. The findings of this study provide data-driven guidelines for water environment policy decisions in the study area.

Admixture of divergent genomes facilitates hybridization across species in the family Brassicaceae.

Hybridization and polyploidization are pivotal to plant evolution. Genetic crosses between distantly related species are rare in nature due to reproductive barriers but how such hurdles can be overcome is largely unknown. Here we report the hybrid genome structure of xBrassicoraphanus, a synthetic allotetraploid of Brassica rapa and Raphanus sativus. We performed cytogenetic analysis and de novo genome assembly to examine chromosome behaviors and genome integrity in the hybrid. Transcriptome analysis was conducted to investigate expression of duplicated genes in conjunction with epigenome analysis to address whether genome admixture entails epigenetic reconfiguration. Allotetraploid xBrassicoraphanus retains both parental chromosomes without genome rearrangement. Meiotic synapsis formation and chromosome exchange are avoided between nonhomologous progenitor chromosomes. Reconfiguration of transcription network occurs, and less divergent cis-elements of duplicated genes are associated with convergent expression. Genome-wide DNA methylation asymmetry between progenitors is largely maintained but, notably, B. rapa-originated transposable elements are transcriptionally silenced in xBrassicoraphanus through gain of DNA methylation. Our results demonstrate that hybrid genome stabilization and transcription compatibility necessitate epigenome landscape adjustment and rewiring of cis-trans interactions. Overall, this study suggests that a certain extent of genome divergence facilitates hybridization across species, which may explain the great diversification and expansion of angiosperms during evolution.

Functional expression and extracellular secretion of Clostridium thermocellum Cel48S cellulase in Escherichia coli via the signal recognition particle-dependent translocation pathway.

As the only glycoside hydrolase family 48 member in Clostridium thermocellum, the exoglucanase Cel48S plays a crucial role in the extremely high activity of the cellulosome against crystalline cellulose. Although the importance of Cel48S in the hydrolysis of crystalline cellulose has been widely accepted, an efficient production system has not yet been established because Cel48S is usually expressed in Escherichia coli within inactive inclusion bodies. For unstable proteins like Cel48S, translocation across the inner membrane can be more advantageous than cytoplasmic production due to the presence of folding modulators in the periplasm and the absence of cytoplasmic proteases. In this study, we evaluated whether the production of Cel48S in the periplasmic space of E. coli could enhance its functional expression. To do so, we attached the PelB signal peptide, which mediates post-translational secretion, to the N-terminal end of Cel48S (P-Cel48S). The PelB signal peptide allowed catalytically active Cel48S to be successfully produced in the culture medium. In addition, we investigated the role of an alternative co-translational pathway on the extracellular production of Cel48S, finding that co-translational secretion yielded a specific activity of recombinant Cel48S of 135.1 ± 10.0 U/mg cell in the culture medium, which was 2.2 times higher than that associated with P-Cel48S expression. Therefore, we believe that our approach has potential applications for the cost-effective conversion of lignocellulosic biomass and the industrial production of other unstable proteins.

Perturbation of the peptidoglycan network and utilization of the signal recognition particle-dependent pathway enhances the extracellular production of a truncational mutant of CelA in Escherichia coli.

Caldicellulosiruptor bescii is the most thermophilic, cellulolytic bacterium known and has the native ability to utilize unpretreated plant biomass. Cellulase A (CelA) is the most abundant enzyme in the exoproteome of C. bescii and is primarily responsible for its cellulolytic ability. CelA contains a family 9 glycoside hydrolase and a family 48 glycoside hydrolase connected by linker regions and three carbohydrate-binding domains. A truncated version of the enzyme (TM1) containing only the endoglucanase domain is thermostable and actively degrades crystalline cellulose. A catalytically active TM1 was successfully produced via the attachment of the PelB signal peptide (P-TM1), which mediates post-translational secretion via the SecB-dependent translocation pathway. We sought to enhance the extracellular secretion of TM1 using an alternative pathway, the signal recognition particle (SRP)-dependent translocation pathway. The co-translational extracellular secretion of TM1 via the SRP pathway (D-TM1) resulted in a specific activity that was 4.9 times higher than that associated with P-TM1 overexpression. In batch fermentations, the recombinant Escherichia coli overexpressing D-TM1 produced 1.86 ± 0.06 U/ml of TM1 in the culture medium, showing a specific activity of 1.25 ± 0.05 U/mg cell, 2.7- and 3.7-fold higher than the corresponding values of the strain overexpressing P-TM1. We suggest that the TM1 secretion system developed in this study can be applied to enhance the capacity of E. coli as a microbial cell factory for the extracellular secretion of this as well as a variety proteins important for commercial production.

Cilioretinal Artery Occlusion after Endovascular Coil Embolization for Anterior Communicating Artery.

Unruptured intracranial aneurysms have a risk of rupture, so coil embolization is widely practiced as it preserves a patent artery. There are complications of coil procedures, such as patent artery occlusion and thromboembolism, which can result in retinal artery occlusion. We report onretinal artery occlusion following coil embolization of anterior communicating artery aneurysm. This is a rare case of a combination of cilioretinal and branch retinal artery occlusion, and is unusual in showing a functional recovery.

Predicting Cyanobacterial Blooms Using Hyperspectral Images in a Regulated River.

Process-based modeling for predicting harmful cyanobacteria is affected by a variety of factors, including the initial conditions, boundary conditions (tributary inflows and atmosphere), and mechanisms related to cyanobacteria growth and death. While the initial conditions do not significantly affect long-term predictions, the initial cyanobacterial distribution in water is particularly important for short-term predictions. Point-based observation data have typically been used for cyanobacteria prediction of initial conditions. These initial conditions are determined through the linear interpolation of point-based observation data and may differ from the actual cyanobacteria distribution. This study presents an optimal method of applying hyperspectral images to establish the Environmental Fluid Dynamics Code-National Institute of Environment Research (EFDC-NIER) model initial conditions. Utilizing hyperspectral images to determine the EFDC-NIER model initial conditions involves four steps that are performed sequentially and automated in MATLAB. The EFDC-NIER model is established using three grid resolution cases for the Changnyeong-Haman weir section of the Nakdong River Basin, where Microcystis dominates during the summer (July to September). The effects of grid resolution on (1) water quality modeling and (2) initial conditions determined using cumulative distribution functions are evaluated. Additionally, the differences in Microcystis values are compared when applying initial conditions using hyperspectral images and point-based evaluation data. Hyperspectral images allow detailed initial conditions to be applied in the EFDC-NIER model based on the plane-unit cyanobacterial information observed in grids, which can reduce uncertainties in water quality (cyanobacteria) modeling.

A genetic characterization of Korean waxy maize (Zea mays L.) landraces having flowering time variation by RNA sequencing.

Maize is the second-most produced crop in the Korean peninsula and has been continuously cultivated since the middle of the 16th century, when it was originally introduced from China. Even with this extensive cultivation history, the diversity and properties of Korean landraces have not been investigated at the nucleotide sequence level. We collected 12 landraces with various flowering times and performed RNA-seq in the early vegetative stage. The transcriptomes of 12 Korean landraces have been analyzed for their genetic variations in coding sequence and genetic relationships to other maize germplasm. The Korean landraces showed specific genetic characteristics and were closely related to a Chinese inbred line. Flowering-time related gene profiles pointed to multiple causes for the variation of flowering time within Korean landraces; the profiles revealed significant positive and negative correlations among genes, allowing us to infer possible mechanisms for flowering time variation in maize. Our results demonstrate the value of transcriptome-based genetic and gene expression profiles for information on possible breeding resources, which is particularly needed in Korean waxy landraces.

Radiofrequency ablation of turbinates after septoplasty has no effect on allergic rhinitis symptoms other than nasal obstruction.

BACKGROUND: In this study we evaluated the effects of inferior turbinate radiofrequency ablation (RFA), performed after septoplasty, on patients with allergic rhinitis (AR) symptoms. METHODS: This was a prospective, randomized, controlled study involving 60 patients with both a deviated nasal septum (DNS) and AR. Those who underwent septoplasty/sham surgery constituted the Septo-Sham group and those who underwent septoplasty/RFA formed the Septo-RFA group. Demographic factors, pre- and postoperative symptom scores for allergic rhinitis (SFARs), and Nasal Obstruction and Septoplasty Effectiveness Scale (NOSE) scores were calculated. We subdivided the total SFAR (tSFAR) scores into scores for nasal obstruction (SFAR-NO) and scores for symptoms other than nasal obstruction (SFAR-SONO); the latter included rhinorrhea, itching, and sneezing. RESULTS: The baseline characteristics were similar between the groups. The 2 types of surgery improved both the NOSE and SFAR scores. In subgroup analysis according to the type of symptoms, both types of surgery showed improvement in SFAR-NO and SFAR-SONO scores. However, the extent of improvement did not differ between the groups, regardless of the type of symptoms. CONCLUSION: For patients with both DNS and AR, both types of surgery afford postoperative symptomatic improvement. Both types of surgery yielded improvement in both nasal obstruction and symptoms other than nasal obstruction. However, performing RFA after septoplasty did not afford further short-term symptomatic improvements. Thus, septoplasty without RFA may be optimal for patients with both DNS and AR.

Accidental Swallowing of Dental Implant: Complication of Transnasal Endoscopic Removal From Maxillary Sinus.

Transnasal endoscopic removal of displaced dental implants in the maxillary sinus can be done easily under local anesthesia. However, very little is known regarding the precaution of this technique. In this report, we present the case of a 63-year-old man who visited the otolaryngologic department with a displaced dental implant in the maxillary sinus. Transnasal endoscopic removal of the displaced dental implant was planned and performed. However, the displaced dental implant was lost during removal. The implant was not seen in the other parts of the nasal cavity nor in the other parts of the oral cavity. Finally, radiographs revealed the presence of the dental implant at the level of the esophagus, although the patient did not notice anything because of local anesthesia. Thus, we conclude that operators should take into account the possibility of aspiration or swallowing of an implant through the posterior nasal aperture during the removal procedure. Precautions should be taken to avoid the possibility of implant aspiration or implant ingestion.

Evaluating physico-chemical influences on cyanobacterial blooms using hyperspectral images in inland water, Korea.

Understanding harmful algal blooms is imperative to protect aquatic ecosystems and human health. This study describes the spatial and temporal distributions of cyanobacterial blooms to identify the relations between blooms and environmental factors in the Baekje Reservoir. Two-year cyanobacterial cell data at one fixed station and four remotely sensed distributions of phycocyanin (PC) concentrations based on hyperspectral images (HSIs) were used to describe the relation between the spatial and temporal variations in the blooms and the affecting factors. An artificial neural network model and a three-dimensional hydrodynamic model were implemented to estimate the PC concentrations using remotely sensed HSIs and simulate the hydrodynamics, respectively. The statistical test results showed that the variations in the cyanobacterial biomass depended significantly on variations in the water temperature (slope = 0.13, p-value < 0.01), total nitrogen (slope = -0.487, p-value < 0.01), and total phosphorus (slope = 20.7, p-value < 0.05), whereas the variation in the biomass was moderately dependent on the variation in the outflow (slope = -0.0097, p-value = 0.065). Water temperature was the main factor affecting variations in the PC concentrations for the three months from August to October and was significantly different for the three months (p-value < 0.01). Hydrodynamic parameters also had a partial effect on the variations in the PC concentrations in those three months. Overall, this study helps to describe spatial and temporal variations in cyanobacterial blooms and identify the factors affecting the variation in the blooms. This study may play an important role as a basis for developing strategies to reduce bloom frequency and severity.

The relative importance of water temperature and residence time in predicting cyanobacteria abundance in regulated rivers.

Despite a growing awareness of the problems associated with cyanobacterial blooms in rivers, and particularly in regulated rivers, the drivers of bloom formation and abundance in rivers are not well understood. We developed a Bayesian hierarchical model to assess the relative importance of predictors of summer cyanobacteria abundance, and to test whether the relative importance of each predictor varies by site, using monitoring data from 16 sites in the four major rivers of South Korea. The results suggested that temperature and residence time, but not nutrient levels, are important predictors of summer cyanobacteria abundance in rivers. Although the two predictors were of similar significance across the sites, the residence time was marginally better in accounting for the variation in cyanobacteria abundance. The model with spatial hierarchy demonstrated that temperature played a consistently significant role at all sites, and showed no effect from site-specific factors. In contrast, the importance of residence time varied significantly from site to site. This variation was shown to depend on the trophic state, indicated by the chlorophyll-a and total phosphorus levels. Our results also suggested that the magnitude of weir inflow is a key factor determining the cyanobacteria abundance under baseline conditions.

Interference cancellation technique of optical AND gate receiver using optical thyristor.

We demonstrate an interference cancellation technique of optical AND gate receiver using optical thyristor for fiber-optic code division multiple access (FO-CDMA) systems. In particular, we fabricate the optical thyristor operating as optical hard-limiter and evaluate that the optical AND gate receiver using fabricated optical thyristor excludes the peaks of side-lobe and cross-correlation result in the system performance degradation. It found that the optical AND gate receiver using optical thyristor excludes the intensity of interference signal resulting in that the peaks of side-lobe and cross-correlation can be fully eliminated for any two users. Therefore, the optical AND gate receiver using optical thyristor is shown to be effective to accommodate more simultaneous users.