Simulation of sequential batch reactor (SBR) operation for simultaneous removal of nitrogen and phosphorus

Modeling of the operation of sequential batch reactor (SBR) was performed to find out optimum design parameters for simultaneous removal of nitrogen and phosphorus in a small-scale wastewater treatment plant. The models were set up with material balances on SBR operation and Monod kinetics. The model parameters were obtained to best fit the experimental results in a small scale SBR. The models were useful in optimizing hydraulic retention time (HRT) and successfully simulated operations of SBR in a larger scale. Especially the model predicted well the reactions occurring in the filling period as well as the effect of dilution, and evaluated the performance of SBR process under diverse operating conditions.     

Patterns of Genetic Diversity in Rare and Common Orchids Focusing on the Korean Peninsula: Implications for Conservation

To provide basic information for orchid conservation, we surveyed the plant allozyme literature to summarize genetic diversity and structure data for (i) rare orchids native to the Korean Peninsula, and (ii) their congeners irrespective of being common and rare or Korean or not. A total of 68 taxa (32 taxa in Korea and 37 outside Korea; Goodyera repens being included in both datasets) were considered in this study. Overall, rare Korean orchid species had significantly lower levels of genetic diversity than their common congeners and common orchids in general at both population and species levels. However, mean values of G _ST (or F _ST) for rare and common orchids (Korean or not) did not differ significantly from each other. We found patterns of both low and high genetic diversity in rare Korean orchids. Many rare orchids harbored a complete lack of allozyme variation or extremely low within-population variation, perhaps due to rarity associated with random genetic drift and/or, for the case of warm-temperate orchids, to founder effects during post-glacial re-colonization. In contrast, high levels of genetic variation were found for a few orchids that have become recently rare (due to over-collection during the past several decades), probably because there have not been sufficient generations for the initial diversity to be substantially eroded. In addition, several orchids occurring in the main mountain system of the Korean Peninsula (the Baekdudaegan), that served as a glacial refugium, maintained moderate to high levels of within-population genetic diversity. Based on our genetic data, conservation priority should be given to rare orchid species. Particularly, urgent measures should be implemented on Jeju Island, a popular vacation spot, because it also a hotspot for threatened orchids with low levels of genetic diversity.     

Metabolic engineering of Mannheimia succiniciproducens for malic acid production using dimethylsulfoxide as an electron acceptor

Microbial production of various TCA intermediates and related chemicals through the reductive TCA cycle has been of great interest. However, rumen bacteria that naturally possess strong reductive TCA cycle have been rarely studied to produce these chemicals, except for succinic acid, due to their dependence on fumarate reduction to transport electrons for ATP synthesis. In this study, malic acid (MA), a dicarboxylic acid of industrial importance, was selected as a target chemical for mass production using Mannheimia succiniciproducens, a rumen bacterium possessing a strong reductive branch of the TCA cycle. The metabolic pathway was reconstructed by eliminating fumarase to prevent MA conversion to fumarate. The respiration system of M. succiniciproducens was reconstructed by introducing the Actinobacillus succinogenes dimethylsulfoxide (DMSO) reductase to improve cell growth using DMSO as an electron acceptor. Also, the cell membrane was engineered by employing Pseudomonas aeruginosa cis-trans isomerase to enhance MA tolerance. High inoculum fed-batch fermentation of the final engineered strain produced 61 g/L of MA with an overall productivity of 2.27 g/L/h, which is the highest MA productivity reported to date. The systems metabolic engineering strategies reported in this study will be useful for developing anaerobic bioprocesses for the production of various industrially important chemicals.     

Cloning of an aminoalcoholphosphotransferase cDNA from chinese cabbage roots

Aminoalcoholphosphotransferase is the enzyme that catalyzes the synthesis of phosphatidylcholine and phosphatidylethanolamine from diacylglycerol using CDP-aminoalcohol such as CDP-choline and CDP-ethanolamine. To determine its cDNA structure from roots of Chinese cabbage,Brassica campestris L. ssp.pekinensis, degenerate primers were designed from the regions showing high amino acid homology between yeastCPT1 and soybeanAAPT1 and used for PCR amplification of Chinese cabbage DNA. Chinese cabbage aminoalcoholphosphotransferase cDNA (AAPT) contains an open reading frame of 1,167 bp coding for a protein of 389 amino acids. It shared 81% identity and 94% similarity with soybeanAAPT1 at the predicted amino acid level. Hydropathy profile analysis suggested that the predicted protein structure of Chinese cabbage aminoalcoholphosphotransferase was very similar to the soybean enzyme, showing an overall hydrophobicity and having the same number of predicted transmembrane domains. Southern analysis indicated that there might be close isoforms of the enzyme.AAPT was expressed equally well in young shoots and roots.     

Diversity and selective pressures of anticoagulants in three medicinal leeches (Hirudinida: Hirudinidae,Macrobdellidae)

Although medicinal leeches have long been used as treatment for various ailments because of their potent anticoagulation factors, neither the full diversity of salivary components that inhibit coagulation, nor the evolutionary selection acting on them has been thoroughly investigated. Here, we constructed expressed sequence tag libraries from salivary glands of two species of medicinal hirudinoid leeches, Hirudo verbana and Aliolimnatis fenestrata, and identified anticoagulant‐orthologs through BLASTx searches. The data set then was augmented by the addition of a previously constructed EST library from the macrobdelloid leech Macrobdella decora. The identified orthologs then were compared and contrasted with well‐characterized anticoagulants from a variety of leeches with different feeding habits, including non‐sanguivorous species. Moreover, four different statistical methods for predicting signatures of positive and negative evolutionary pressures were used for 10 rounds each to assess the level and type of selection acting on the molecules as a whole and on specific sites. In total, sequences showing putative BLASTx‐orthology with five and three anticoagulant‐families were recovered in the A. fenestrata and H. verbana EST libraries respectively. Selection pressure analyses predicted high levels of purifying selection across the anticoagulant diversity, although a few isolated sites showed signatures of positive selection. This study represents a first attempt at mapping the anticoagulant repertoires in a comparative fashion across several leech families.     

Suppressive effect of epigallocatechin‐3‐O‐gallate on endoglin molecular regulation in myocardial fibrosis in vitro and in vivo

Epigallocatechin‐3‐O‐gallate (EGCG), derived from green tea, has been studied extensively because of its diverse physiological and pharmacological properties. This study evaluates the protective effect of EGCG on angiotensin II (Ang II)‐induced endoglin expression in vitro and in vivo. Cardiac fibroblasts (CFs) from the thoracic aorta of adult Wistar rats were cultured and induced with Ang II. Western blotting, Northern blotting, real‐time PCR and promoter activity assay were performed. Ang II increased endoglin expression significantly as compared with control cells. The specific extracellular signal‐regulated kinase inhibitor SP600125 (JNK inhibitor), EGCG (100 μM) and c‐Jun N‐terminal kinase (JNK) siRNA attenuated endoglin proteins following Ang II induction. In addition, pre‐treated Ang II‐induced endoglin with EGCG diminished the binding activity of AP‐1 by electrophoretic mobility shift assay. Moreover, the luciferase assay results revealed that EGCG suppressed the endoglin promoter activity in Ang II‐induced CFs by AP‐1 binding. Finally, EGCG and the JNK inhibitor (SP600125) were found to have attenuated endoglin expression significantly in Ang II‐induced CFs, as determined through confocal microscopy. Following in vivo acute myocardial infarction (AMI)‐related myocardial fibrosis study, as well as immunohistochemical and confocal analyses, after treatment with endoglin siRNA and EGCG (50 mg/kg), the area of myocardial fibrosis reduced by 53.4% and 64.5% and attenuated the left ventricular end‐diastolic and systolic dimensions, and friction shortening in hemodynamic monitor. In conclusion, epigallocatechin‐3‐O‐gallate (EGCG) attenuated the endoglin expression and myocardial fibrosis by anti‐inflammatory effect in vitro and in vivo, the novel suppressive effect was mediated through JNK/AP‐1 pathway.