An effective chemical pretreatment method for lignocellulosic biomass with substituted imidazoles

Lignocellulosic biomass is the most abundant naturally renewable organic resource for biofuel production. Because of its recalcitrance to enzymatic degradation, pretreatment is a crucial step before hydrolysis of the feedstock. A variety of pretreatment methods have been developed and intensively studied to achieve optimal yield without imposing significant adverse impact on the environment. Herein, we present a novel chemical pretreatment method using substituted heterocycles with low temperature and short residence time requirements. 1‐Methylimidazole (MI) is a precursor to some imidazolium‐based ionic liquids. In this study, its potential utilization as a biomass pretreatment agent is being investigated for the first time. At mild conditions, such as 25°C for 5 min at ambient pressure, a substantial increase in the hydrolysis rate throughout the entire course of conversion for cellulose substrate was obtained. Furthermore, the pretreatment effectiveness of MI on both untreated and steam‐exploded lignocellulosic biomass including loblolly pine, switchgrass, and sugarcane bagasse has been studied and MI was found to be an efficient delignifier. Remarkable rate enhancement was also observed for the non‐woody lignocellulosic substrates after a short period of MI pretreatment at ambient conditions. The mechanism of MI pretreatment is explored through analysis of cellulose physical properties including crystallinity index, degree of polymerization, accessibility, and lignin dissolution quantification. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 31:25–34, 2015     

Thermogelling aqueous solutions of alternating multiblock copolymers of poly(L-lactic acid) and poly(ethylene glycol)

We are reporting alternating multiblock copolymers of poly(L-lactic acid)/poly(ethylene glycol) aqueous solution (> 15 wt %) undergoing sol-gel-sol transition as the temperature increases from 20 to 60 degrees C. Micelles of the multiblock copolymers (in water) are about 20 nm in radius at low temperature. They are aggregated to a larger size as the temperature increases, which should play a critical role in the sol-to-gel transition. The transition temperature and gel window were affected by the molecular weight and composition of the multiblock copolymer. In particular, the aqueous solution of an alternating multiblock copolymer (Mn approximately 6700 daltons) prepared from poly(ethylene glycol) (Mn approximately 600 daltons) and poly(L-lactic acid) (Mn approximately 1300 daltons) showed a maximum modulus at body temperature (37 degrees C). The in situ gel forming ability of the polymer aqueous solution in vivo as well as in vitro indicates that it can be a promising injectable biomaterial.     

Prevalence of Clonorchis sinensis metacercariae in freshwater fish from three latitudinal regions of the Korean Peninsula

A large-scale survey was conducted to investigate the infection status of fresh water fishes with Clonorchis sinensis metacercariae (CsMc) in 3 wide regions, which were tentatively divided by latitudinal levels of the Korean peninsula. A total of 4,071 freshwater fishes were collected from 3 regions, i.e., northern (Gangwon-do: 1,543 fish), middle (Chungcheongbuk-do and Gyeongsangbuk-do: 1,167 fish), and southern areas (Jeollanam-do, Ulsan-si, and Gyeongsangnam-do: 1,361 fish). Each fish was examined by the artificial digestion method from 2003 to 2010. In northern areas, only 11 (0.7%) fish of 2 species, Pungtungia herzi and Squalidus japonicus coreanus from Hantan-gang, Cheolwon-gun, Gangwon-do were infected with av. 2.6 CsMc. In middle areas, 149 (12.8%) fish were infected with av. 164 CsMc. In southern areas, 538 (39.5%) fish were infected with av. 159 CsMc. In the analysis of endemicity in 3 regions with an index fish, P. herzi, 9 (6.2%) of 146 P. herzi from northern areas were infected with av. 2.8 CsMc. In middle areas, 34 (31.8%) of 107 P. herzi were infected with av. 215 CsMc, and in southern areas, 158 (92.9%) of 170 P. herzi were infected with av. 409 CsMc. From these results, it has been confirmed that the infection status of fish with CsMc is obviously different among the 3 latitudinal regions of the Korean peninsula with higher prevalence and burden in southern regions.     

Inhibition of Taq DNA polymerase by seaweed extracts from British Columbia, Canada and Korea

Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity. At the concentration of 5 μg of methanol extract in 25μL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase, one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula) of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal) have been found to inhibit PCR at level as low as 0.5 μg in 25μL of PCR reaction mixture. This revised version was published online in August 2006 with corrections to the Cover Date.     

FE65 as a link between VLDLR and APP to regulate their trafficking and processing

Background

Loss-of-function mutations in PTEN-induced kinase 1 (PINK1) have been linked to familial Parkinson??s disease, but the underlying pathogenic mechanism remains unclear. We previously reported that loss of PINK1 impairs mitochondrial respiratory activity in mouse brains.

Results

In this study, we investigate how loss of PINK1 impairs mitochondrial respiration using cultured primary fibroblasts and neurons. We found that intact mitochondria in PINK1?/? cells recapitulate the respiratory defect in isolated mitochondria from PINK1?/? mouse brains, suggesting that these PINK1?/? cells are a valid experimental system to study the underlying mechanisms. Enzymatic activities of the electron transport system complexes are normal in PINK1?/? cells, but mitochondrial transmembrane potential is reduced. Interestingly, the opening of the mitochondrial permeability transition pore (mPTP) is increased in PINK1?/? cells, and this genotypic difference between PINK1?/? and control cells is eliminated by agonists or inhibitors of the mPTP. Furthermore, inhibition of mPTP opening rescues the defects in transmembrane potential and respiration in PINK1?/? cells. Consistent with our earlier findings in mouse brains, mitochondrial morphology is similar between PINK1?/? and wild-type cells, indicating that the observed mitochondrial functional defects are not due to morphological changes. Following FCCP treatment, calcium increases in the cytosol are higher in PINK1?/? compared to wild-type cells, suggesting that intra-mitochondrial calcium concentration is higher in the absence of PINK1.

Conclusions

Our findings show that loss of PINK1 causes selective increases in mPTP opening and mitochondrial calcium, and that the excessive mPTP opening may underlie the mitochondrial functional defects observed in PINK1?/? cells.     

Robust test method for time-course microarray experiments

Background  

In a time-course microarray experiment, the expression level for each gene is observed across a number of time-points in order to characterize the temporal trajectories of the gene-expression profiles. For many of these experiments, the scientific aim is the identification of genes for which the trajectories depend on an experimental or phenotypic factor. There is an extensive recent body of literature on statistical methodology for addressing this analytical problem. Most of the existing methods are based on estimating the time-course trajectories using parametric or non-parametric mean regression methods. The sensitivity of these regression methods to outliers, an issue that is well documented in the statistical literature, should be of concern when analyzing microarray data.     

Sample size calculation for microarray experiments with blocked one-way design

Background  

One of the main objectives of microarray analysis is to identify differentially expressed genes for different types of cells or treatments. Many statistical methods have been proposed to assess the treatment effects in microarray experiments.     

Isolation and characterization of proteorhodopsin homologue from Yellow Sea of Korea

Many organisms use proton pump to earn energy for living. Some proton pumps start to work by light and one of the famous proteins are called proteorhodopsin (PR). From recent study it used not only protons but also mono-valent cations, divalent cations, or mono-valent anions during pumping activity. The goal of this study is to find new types of proton pumping proteins in the surface of the ocean. Metagenome samples were collected from the beach in Taean-gun and Incheon (Kkotji beach (36°30′0′′N, 126°19′56′′E), Kkotji mud (36°30′8′′N, 126°19′60′′E), Duegi beach (36°31′6′′N, 126°19′39′′E), Sorae salt pond (37°24′25′′N, 126°44′41′′E), swamp (37°24′59′′N, 126°44′54′′E) and reservoir (37°24′39′′N, 126°45′5′′E) in West Sea of Korea. Genomic DNA of each sample was isolated and used for PCR with specific primers for PR and sodium pumping rhodopsin. As a result, we obtained an unidentified PR in Duegi beach sample. The unidentified PR was expressed with chimeric expression system. It has 528 nm absorption maximum at pH 7. By the light differential spectrum measurement, putative M and O photo-intermediates were detected at around 400 and 600 nm, respectively. Similar to GPR, it has light driven outward proton transfer activity.     

Plasmodium vivax: molecular cloning, expression and characterization of glutathione S-transferase

Malaria parasite glutathione S-transferases (GSTs) are postulated to be essential for parasite survival by protecting the parasite against oxidative stress and buffering the detoxification of heme-binding compounds; therefore, GSTs are considered potential targets for drug development. In this study, we identified a Plasmodium vivax gene encoding GST (PvGST) and characterized the biochemical properties of the recombinant enzyme. The PvGST contained 618 bp that encoded 205 amino acids and shared a significant degree of sequence identity with GSTs from other Plasmodium species. The recombinant homodimeric enzyme had an approximate molecular mass of 50kDa and exhibited GSH-conjugating and GSH-peroxidase activities towards various model substrates. The optimal pH for recombinant PvGST (rPvGST) activity was pH 8.0, and the enzyme was moderately unstable at 37 degrees C. The K(m) values of rPvGST with respect to GSH and CDNB were 0.17+/-0.09 and 2.1+/-0.4mM, respectively. The significant sequence homology and similar biochemical properties of PvGST and Plasmodium falciparum GST (PfGST) indicate that they may have similar molecular structures. This information may be useful for the design of specific inhibitors for plasmodial GSTs as potential antimalarial drugs.