JBB : Journal of Bioscience and Bioengineering

JBB Vol. 124表紙  

JBB 新着20報



  • Molecular mechanisms of the yeast adaptive response and tolerance to stresses encountered during ethanol fermentation
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Choowong Auesukaree

    During ethanol fermentation, yeast cells encounter various stresses including sugar substrates-induced high osmolarity, increased ethanol concentration, oxygen metabolism-derived reactive oxygen species (ROS), and elevated temperature. To cope with these fermentation-associated stresses, appropriate adaptive responses are required to prevent stress-induced cellular dysfunctions and to acquire stress tolerances. This review will focus on the cellular effects of these stresses, molecular basis of the adaptive response to each stress, and the cellular mechanisms contributing to stress tolerance. Since a single stress can cause diverse effects, including specific and non-specific effects, both specific and general stress responses are needed for achieving comprehensive protection. For instance, the high-osmolarity glycerol (HOG) pathway and the Yap1/Skn7-mediated pathways are specifically involved in responses to osmotic and oxidative stresses, respectively. On the other hand, due to the common effect of these stresses on disturbing protein structures, the upregulation of heat shock proteins (HSPs) and trehalose is induced upon exposures to all of these stresses. A better understanding of molecular mechanisms underlying yeast tolerance to these fermentation-associated stresses is essential for improvement of yeast stress tolerance by genetic engineering approaches.





  • Inactivation kinetics and conformation change of Hypocrea orientalis β-glucosidase with guanidine hydrochloride
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Xin-Qi Xu, Wei Han, Xiao-Bing Wu, Yong Xie, Juan Lin, Qing-Xi Chen

    The relationship between unfolding and inactivation of Hypocrea orientalis β-glucosidase has been investigated for the first time. The secretion of β-glucosidase from H. orientalis is induced by raw cassava residues. The enzyme was 75 kD without glycosylation. Guanidine hydrochloride (GuHCl) could reversibly inactivate the enzyme with an estimated IC 50 value of 0.4 M. The inactivation kinetics model by GuHCl has been established and the microscopic inactivation rate constants are determined. The values of forward inactivation rate constants of free enzyme are found to be larger than that of substrate–enzyme complex suggesting the enzyme could be protected by substrate during denaturation. Conformational change of the enzyme during denaturation is observed as the intrinsic fluorescence emission peaks appeared red-shift (334–354 nm) with intensity decreased following increase of GuHCl concentrations. Inactivation extent is found to be greater than conformation change of the whole enzyme, indicating that the active site of H. orientalis β-glucosidase might be a more flexible region than the whole enzyme.





  • Scale-up and inhibitory studies on productivity of lipase from Acinetobacter radioresistens PR8
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Krishna Kant Gupta, Anshul Nigam, Sharmili Jagtap, Ramadas Krishna

    Acinetobacter radioresistens PR8 produces extracellular lipase depending upon growth media. In present work we not only screened the nutrient sources but also investigated the causes for variation in productivity. The nutrient sources investigated are, groundnut oil, groundnut cake and fresh groundnut. Lower lipase productivity was observed on fresh ground nut in contrast to groundnut oil and groundnut cake. The lipase productivity was examined in the batch and parameters monitored were bacterial growth, enzyme activity, pH, lipids and protein concentration. The aflatoxin B1 and oxalic acid present in fresh groundnut were found to be responsible for lower lipase productivity. The interaction studies of oxalic acid and purified lipase was confirmed with CD spectra analysis, isothermal titration calorimetry studies and fluorescence quenching. Therefore, the importance of economical cheap groundnut cake with no aflatoxin B1 and oxalates are proposed to be used for optimum lipase production.





  • Efficient antibody production in the methylotrophic yeast Ogataea minuta by overexpression of chaperones
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Takeshi Suzuki, Satoshi Baba, Minako Ono, Koichi Nonaka, Kimihisa Ichikawa, Masayuki Yabuta, Rie Ito, Yasunori Chiba

    A production system for a therapeutic monoclonal antibody was developed using the methylotrophic yeast Ogataea minuta IFO10746. The genetically engineered O. minuta secreted a detectable amount of anti-TRAIL receptor antibody into the culture supernatant, and the secreted antibody was purified by multiple column chromatography steps. In the purification process, both fully and partially assembled antibodies were detected and isolated. The fully assembled antibody from O. minuta showed almost the same biological activity as that derived from mammalian cells despite the distinct glycosylation profile, whereas the partially assembled antibody showed no cytotoxic activity. To increase the production of active antibody in O. minuta, we overexpressed selected chaperone proteins (included protein disulfide isomerase (OmPDI1), thiol oxidase (OmERO1), and immunoglobulin heavy chain binding protein (OmKAR2)) known to assist in the proper folding (in the endoplasmic reticulum) of proteins destined for secretion. Each of these chaperones enhanced antibody secretion, and together these three factors yielded 16-fold higher antibody accumulation while increasing the ratio of the fully assembled antibody compared to that from the parental strain. Supplementation of a rhodanine-3-acetic acid derivative (R3AD_1c), an inhibitor of O-mannosylation, further increased the secretion of the correctly assembled antibody. These results indicated that the co-overexpression of chaperones is an effective way to produce the correctly assembled antibody in O. minuta.





  • Evaluation of Saccharomyces cerevisiae GAS1 with respect to its involvement in tolerance to low pH and salt stress
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Akinori Matsushika, Toshihiro Suzuki, Tetsuya Goshima, Tamotsu Hoshino

    We previously showed that overexpression of IoGAS1, which was isolated from the multiple stress-tolerant yeast Issatchenkia orientalis, endows Saccharomyces cerevisiae cells with the ability to grow and ferment under acidic and high-salt conditions. The deduced amino acid sequence of the IoGAS1 gene product exhibits 60% identity with the S. cerevisiae Gas1 protein, a glycosylphosphatidylinositol-anchored protein essential for maintaining cell wall integrity. However, the functional roles of ScGAS1 in stress tolerance and pH regulation remain unclear. In the present study, we characterized ScGAS1 regarding its roles in tolerance to low pH and high salt concentrations. Transcriptional analysis indicated that, as for the IoGAS1 gene, ScGAS1 expression was pH dependent, with maximum expression at pH 3.0; the presence of salt increased endogenous expression of both GAS1 genes at almost all pH levels. These results suggested that ScGAS1, like IoGAS1, is involved in a novel acid- and salt-stress adaptation mechanism in S. cerevisiae. Overexpression of ScGAS1 in S. cerevisiae improved growth and ethanol production from glucose under acid stress without added salt, although the stress tolerance of the ScGAS1-overexpressing strain was inferior to that of the IoGAS1-overexpressing strain. However, overexpression of ScGAS1 did not result in increased tolerance of S. cerevisiae to combined acid and salt stress, even though ScGAS1 appears to be a salt-responsive gene. Thus, ScGAS1 is directly implicated in tolerance to low pH but does not confer salinity tolerance, supporting the view that ScGAS1 and IoGAS1 have overlapping yet distinct roles in stress tolerance in yeast.





  • Analysis of the oligosaccharides in Japanese rice wine, sake, by hydrophilic interaction liquid chromatography–time-of-flight/mass spectrometry
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Masafumi Tokuoka, Chihiro Honda, Akira Totsuka, Hitoshi Shindo, Masaru Hosaka

    A traditional Japanese alcoholic beverage, sake, contains several oligosaccharides, which are associated with the taste of sake; however, little is known about the specific molecular species and concentrations of oligosaccharides in sake. Here, we developed an analytical method using hydrophilic interaction liquid chromatography–time-of-flight/mass spectrometry (HILIC-TOF/MS) which successfully detects the oligosaccharides in sake. A series of oligosaccharides with successive degree of polymerization (DP) values up to 18 were identified in sake for the first time, which we have named sake oligosaccharides (SAOs). The concentrations of the SAOs with DP = 3–8 were estimated to be in the range of 200–2000 ppm. Quantitative analysis of 6 different sake samples for SAOs with DP=2–8 and the other saccharides showed that the amount of each SAO differs significantly among the sake samples. Enzymatic digestion analysis suggested that the SAOs are probably branched maltooligosaccharides in structure, which are resistant to β-amylase.





  • Metabolite profile of koji amazake and its lactic acid fermentation product by Lactobacillus sakei UONUMA
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Yoshifumi Oguro, Toshikazu Nishiwaki, Ryota Shinada, Kazuya Kobayashi, Atsushi Kurahashi

    The koji amazake is a traditional sweet Japanese beverage. It has been consumed for over a thousand years in Japan; nonetheless, little is yet known of the ingredients in koji amazake. Therefore, this study aimed to analyze the metabolites of koji amazake using a metabolomics approach. Additionally, we reformed the flavor of koji amazake by lactic acid fermentation (LAF-amazake) using Lactobacillus sakei UONUMA, which was isolated from snow caverns. The purpose of this article is to identify the ingredients in these beverages. In LAF-amazake and koji amazake, sugars, amino acids, organic acids, and vitamin B complex were determined in the two beverages, and over 300 compounds were detected in total. Thirteen saccharides were identified including two unknown trisaccharides, and there were no differences in these between the two beverages. In LAF-amazake, lactic acid, vitamin B2 (riboflavin), B3 (nicotinic acid and nicotinamide), and B6 (pyridoxine) were significantly increased as compared to koji amazake, whereas malate and glutamine decreased. These results suggested that LAF, malolactic fermentation, and glutamine deamidation occurred simultaneously in LAF-amazake. L. sakei UONUMA strains produced these vitamins. Moreover, it was surprising that acetylcholine, a well-known neurotransmitter, was newly generated in LAF-amazake. Here, we have succeeded in reforming the flavor of koji amazake and obtained these metabolic data on the two beverages. The present study could provide useful basic information for promoting functional analyses of koji amazake and LAF-amazake for human health.





  • Production of bioethanol from Napier grass via simultaneous saccharification and co-fermentation in a modified bioreactor
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Yu-Kuo Liu, Wei-Chuan Chen, Yu-Ching Huang, Yu-Kaung Chang, I-Ming Chu, Shen-Long Tsai, Yu-Hong Wei

    The aim of this study was to use a modified bioreactor system for simultaneous saccharification of cellulose and bioethanol production. We tested Aspergillus niger and Trichoderma reesei for cellulose saccharification and Zymomonas mobilis for bioethanol production simultaneously in this modified bioreactor. The results showed that various carboxymethylcellulose (CMC) concentrations (10, 15, or 20 g/L) as a substrate for A. niger and T. reesei yielded bioethanol production of 0.51, 0.78, and 0.89 g/L and a CMC conversion rate of 10.2%, 10.7%, and 8.89%, respectively. These data suggested that at 10 g/L CMC as a substrate, the CMC conversion rate was higher than that at the other concentrations. When CMC concentration exceeded 15 g/L, bioethanol production was prolonged to 40 h. These results were attributed to the viscosity of CMC. This study also tested Napier grass (an agricultural byproduct) for bioethanol production. The results revealed bioethanol production and the theoretical Napier grass conversion rate were 0.38 g/L and 12.6%, respectively, for 13-h cultivation when the feeding concentration of Napier grass was 10 g/L. When Napier grass concentration was increased to 15 g/L, bioethanol production and the Napier grass conversion rate reached 0.51 g/L and 23%, respectively, after 14-h cultivation. Eventually, the experimental results indicated using agricultural waste for bioethanol production has been become a potential strategy.





  • Starch-fueled microbial fuel cells by two-step and parallel fermentation using Shewanella oneidensis MR-1 and Streptococcus bovis 148
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Megumi Uno, Nichanan Phansroy, Yuji Aso, Hitomi Ohara

    Shewanella oneidensis MR-1 generates electricity from lactic acid, but cannot utilize starch. On the other hand, Streptococcus bovis 148 metabolizes starch and produces lactic acid. Therefore, two methods were trialed for starch-fueled microbial fuel cell (MFC) in this study. In electric generation by two-step fermentation (EGT) method, starch was first converted to lactic acid by S. bovis 148. The S. bovis 148 were then removed by centrifugation, and the fermented broth was preserved for electricity generation by S. oneidensis MR-1. Another method was electric generation by parallel fermentation (EGP) method. In this method, the cultivation and subsequent fermentation processes of S. bovis 148 and S. oneidensis MR-1 were performed simultaneously. After 1, 2, and 3 terms (5-day intervals) of S. oneidensis MR-1 in the EGT fermented broth of S. bovis 148, the maximum currents at each term were 1.8, 2.4, and 2.8 mA, and the maximum current densities at each term were 41.0, 43.6, and 49.9 mW/m2, respectively. In the EGP method, starch was also converted into lactic acid with electricity generation. The maximum current density was 140–200 mA/m2, and the maximum power density of this method was 12.1 mW/m2.





  • Conversion of vegetable wastes to organic acids in leaching bed reactor: Performance and bacterial community analysis
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Yan Li, Dongliang Hua, Hui Mu, Haipeng Xu, Fuqiang Jin, Xiaodong Zhang

    Vegetable wastes (VWs), which contained abundant solid content, were digested in a leaching bed reactor (LBR). The tested VWs for acidification in the LBR included cabbage, potato, and tomato vine. The digestion in the LBR was carried out at the same organic loading rate of 25 g volatile solid (VS) per liter. It was found that cabbage and potato produced much more volatile fatty acids (VFAs) than tomato vine, probably because readily degradable components were more abundant in cabbage and potato. The retention time to digest each feedstock was different. It took 4, 5, and 8 days for cabbage, potato, and tomato vine to completely disappear in the reactor, respectively. The profiles of the VFAs generated from the three VWs were examined. In all cases, the predominant VFAs were acetic acid and butyric acid, although the relative abundance of individual VFA varied across the tested leachate samples. The bacterial community compositions of the leachates were analyzed by high throughput sequencing, and it was found that the feedstock strongly affected the bacterial community structure in the acidogenic process. All leachates had distinct bacterial community structure, although they did share a common set of core communities that included Proteobacteria, Firmicutes, and Bacteroidetes.





  • Microbial secretion of lactate-enriched oligomers for efficient conversion into lactide: A biological shortcut to polylactide
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Camila Utsunomia, Ken'ichiro Matsumoto, Sakiko Date, Chiaki Hori, Seiichi Taguchi

    Recently, we have succeeded in establishing the microbial platform for the secretion of lactate (LA)-based oligomers (D-LAOs), which consist of D-LA and d-3-hydroxybutyrate (d-3HB). The secretory production of D-LAOs was substantially enhanced by the supplementation of diethylene glycol (DEG), which resulted in the generation of DEG-capped oligomers at the carboxyl terminal (referred as D-LAOs-DEG). The microbial D-LAOs should be key compounds for the synthesis of lactide, an important intermediate for polylactides (PLAs) production, eliminating the costly chemo-oligomerization step in the PLA production process. Therefore, in order to demonstrate a proof-of-concept, here, we attempted to convert the D-LAOs-DEG into lactide via metal-catalyzed thermal depolymerization. As a result, D-LAOs-DEG containing 68 mol% LA were successfully converted into lactide, revealing that the DEG bound to D-LAOs-DEG does not inhibit the conversion into lactide. However, the lactide yield (4%) was considerably lower than that of synthetic LA homo-oligomers (33%). We presumed that 3HB units in the polymer chain blocked the lactide formation, and therefore, we investigated the LA enrichment in the oligomers. As the results, the combination of an LA-overproducing Escherichia coli mutant (Δdld and ΔpflA) with the use of xylose as a carbon source exhibited synergistic effect to increase LA fraction in the oligomers up to 89 mol%. The LA-enriched D-LAOs-DEG were converted into lactide with greater yield (18%). These results demonstrated that a greener shortcut route for PLA production can be created by using the microbial D-LAOs secretion system.





  • Effective modification of cell death-inducing intracellular peptides by means of a photo-cleavable peptide array-based screening system
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Ikko Kozaki, Kazunori Shimizu, Hiroyuki Honda

    Intracellular functional peptides that play a significant role inside cells have been receiving a lot of attention as regulators of cellular activity. Previously, we proposed a novel screening system for intracellular functional peptides; it combined a photo-cleavable peptide array system with cell-penetrating peptides (CPPs). Various peptides can be delivered into cells and intracellular functions of the peptides can be assayed by means of our system. The aim of the present study was to demonstrate that the proposed screening system can be used for assessing the intracellular activity of peptides. The cell death-inducing peptide (LNLISKLF) identified in a mitochondria-targeting domain (MTD) of the Noxa protein served as an original peptide sequence for screening of peptides with higher activity via modification of the peptide sequence. We obtained 4 peptides with higher activity, in which we substituted serine (S) at the fifth position with phenylalanine (F), valine (V), tryptophan (W), or tyrosine (Y). During analysis of the mechanism of action, the modified peptides induced an increase in intracellular calcium concentration, which was caused by the treatment with the original peptide. Higher capacity for cell death induction by the modified peptides may be caused by increased hydrophobicity or an increased number of aromatic residues. Thus, the present work suggests that the intracellular activity of peptides can be assessed using the proposed screening system. It could be used for identifying intracellular functional peptides with higher activity through comprehensive screening.





  • Repression of the DCL2 and DCL4 genes in Nicotiana benthamiana plants for the transient expression of recombinant proteins
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Kouki Matsuo, Takeshi Matsumura

    The production of recombinant proteins in plants has many advantages, including safety and reduced costs. However, this technology still faces several issues, including low levels of production. The repression of RNA silencing seems to be particularly important for improving recombinant protein production because RNA silencing effectively degrades transgene-derived mRNAs in plant cells. Therefore, to overcome this, we used RNA interference technology to develop DCL2- and DCL4-repressed transgenic Nicotiana benthamiana plants (ΔD2, ΔD4, and ΔD2ΔD4 plants), which had much lower levels of NbDCL2 and/or NbDCL4 mRNAs than wild-type plants. A transient gene expression assay showed that the ΔD2ΔD4 plants accumulated larger amounts of green fluorescent protein (GFP) and human acidic fibroblast growth factor (aFGF) than ΔD2, ΔD4, and wild-type plants. Furthermore, the levels of GFP and aFGF mRNAs were also higher in ΔD2ΔD4 plants than in ΔD2, ΔD4, and wild-type plants. These findings demonstrate that ΔD2ΔD4 plants express larger amounts of recombinant proteins than wild-type plants, and so would be useful for recombinant protein production.





  • Efficient production of antibody Fab fragment by transient gene expression in insect cells
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Keita Mori, Hirotsugu Hamada, Takafumi Ogawa, Yuki Ohmuro-Matsuyama, Tomohisa Katsuda, Hideki Yamaji

    Transient gene expression allows a rapid production of diverse recombinant proteins in early-stage preclinical and clinical developments of biologics. Insect cells have proven to be an excellent platform for the production of functional recombinant proteins. In the present study, the production of an antibody Fab fragment by transient gene expression in lepidopteran insect cells was investigated. The DNA fragments encoding heavy-chain (Hc; Fd fragment) and light-chain (Lc) genes of an Fab fragment were individually cloned into the plasmid vector pIHAneo, which contained the Bombyx mori actin promoter downstream of the B. mori nucleopolyhedrovirus (BmNPV) IE-1 transactivator and the BmNPV HR3 enhancer for high-level expression. Trichoplusia ni BTI-TN-5B1-4 (High Five) cells were co-transfected with the resultant plasmid vectors using linear polyethyleneimine. When the transfection efficiency was evaluated, a plasmid vector encoding an enhanced green fluorescent protein (EGFP) gene was also co-transfected. Transfection and culture conditions were optimized based on both the flow cytometry of the EGFP expression in transfected cells and the yield of the secreted Fab fragments determined by enzyme-linked immunosorbent assay (ELISA). Under optimal conditions, a yield of approximately 120 mg/L of Fab fragments was achieved in 5 days in a shake-flask culture. Transient gene expression in insect cells may offer a promising approach to the high-throughput production of recombinant proteins.





  • Phenotypic heterogeneity of human retinal pigment epithelial cells in passaged cell populations
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Rie Sonoi, Mee-Hae Kim, Kenta Yamada, Masahiro Kino-oka

    Human retinal pigment epithelial (RPE) cells at different population doublings (PDs) were cultured for 28 days to examine their phenotypic heterogeneity in a confluent state. In an early population (PD = 2.8), cells showed a cobblestone-like appearance (type I), which gradually became small and tight, and eventually exhibited dark pigmentation. Some cells showed a dome-like structure (type II), which detached from the culture surface during culture. With increasing PD, the cells showed active migration that caused a shift in phenotype from a single layer of large, flattened cells (type III) to a multiple cell layers (stratified) with flattened, irregularly shaped cells (type IV). Immunostaining of specific RPE markers, ZO-1 and Na+/K+-ATPase revealed that cells have markedly decreased expressions in a late population (PD = 10.1). RPE phenotypes were classified into four types by measuring the nuclear size and local density. The frequencies of type I cells decreased with increasing PD value, while the frequencies of type III and IV cells increased along with the decrease in type I. The frequencies of type IV cells at PD = 10.1 had increased by 10.3-fold compared with PD = 2.8. From these results, the nuclear size and local density were proposed as indicators for understanding phenotypic heterogeneity of RPE cells in the passaged cell population during cell expansion. It is concluded that the population doubling level is an important factor to affect the transition of RPE phenotype and thereby to modulate the quality of cultured cells.





  • Compartmentalized microfluidic perfusion system to culture human induced pluripotent stem cell aggregates
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Yuki Kondo, Koji Hattori, Shota Tashiro, Eri Nakatani, Ryosuke Yoshimitsu, Taku Satoh, Shinji Sugiura, Toshiyuki Kanamori, Kiyoshi Ohnuma

    Microfluidic perfusion systems enable small-volume cell cultures under precisely controlled microenvironments, and are typically developed for cell-based high-throughput screening. However, most such systems are designed to manipulate dissociated single cells, not cell aggregates, and are thus unsuitable to induce differentiation in human induced pluripotent stem cells (hiPSCs), which is conventionally achieved by using cell aggregates to increase cell–cell interactions. We have now developed a compartmentalized microfluidic perfusion system with large flow channels to load, culture, and observe cell aggregates. Homogeneously sized cell aggregates to be loaded into the device were prepared by shredding flat hiPSC colonies into squares. These aggregates were then seeded into microchambers coated with fibronectin and bovine serum albumin (BSA) to establish adherent and floating cultures, respectively, both of which are frequently used to differentiate hiPSCs. However, the number of aggregates loaded in fibronectin-coated microchambers was much lower than in BSA-coated microchambers, suggesting that fibronectin traps cell aggregates before they reach the chambers. Accordingly, hiPSCs that reached the microchambers subsequently adhered. In contrast, BSA-coated microchambers did not allow cell aggregates to adhere, but were sufficiently deep to prevent cell aggregates from flowing out during perfusion of media. Immunostaining for markers of undifferentiated cells showed that cultures on both fibronectin- and BSA-coated microchambers were successfully established. Notably, we found that floating aggregates eventually adhered to surfaces coated with BSA upon differentiation, and that differentiation depends on the initial size of aggregates. Collectively, these results suggest that the microfluidic system is suitable for manipulating hiPSC aggregates in compartmentalized microchambers.





  • Establishment of MicroRNA delivery system by PP7 bacteriophage-like particles carrying cell-penetrating peptide
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Yanli Sun, Yanhua Sun, Ronglan Zhao

    MicroRNAs have great therapeutic potential in cancer and other diseases. However, their instability and low in vivo delivery efficiency limits their application. Recombinant PP7 bacteriophage-based virus-like particles (VLPs) could protect microRNAs against rapid degradation by RNase by packaging specific exogenous pre-microRNAs using the pac site. Insertion of a cell-penetrating peptide (CPP) into the AB-loop of VLPs could significantly improve the delivery efficiency of microRNAs into mammalian cells. Unlike other microRNA delivery methods (viral or non-viral vectors), recombinant PP7 VLPs carrying a CPP and microRNA could be efficiently expressed in Escherichia coli using the one-plasmid double expression system. Here we showed that PP7 VLPs carrying a CPP penetrated hepatoma SK-HEP-1 cells and delivered the pre-microRNA-23b, which was processed into a mature product within 24 h; a concentration of 10 nM was sufficient for the inhibition of hepatoma cell migration via the downregulation of liver-intestine cadherin expression. Furthermore, PP7 VLPs carrying a CPP and a pre-microRNA were not infectious, replicative, or cytotoxic. Therefore, recombinant PP7 VLPs can be used for simultaneous and targeted delivery of both microRNAs and peptides because of their ability to package specific exogenous RNA using the pac site and to display peptides.





  • Simple and rapid method for isolation and quantitation of polyhydroxyalkanoate by SDS-sonication treatment
    Publication date: August 2017
    Source:Journal of Bioscience and Bioengineering, Volume 124, Issue 2

    Author(s): Hisashi Arikawa, Shunsuke Sato, Tetsuya Fujiki, Keiji Matsumoto

    We developed a new method for isolation and quantitation of polyhydroxyalkanoate (PHA) from culture broth. In this method, the cells were sonicated in sodium dodecyl sulfate (SDS) solution and centrifuged to recover PHA. The recovered PHA was rinsed with deionized water and ethanol, and then weighed after drying. Hazardous chemicals such as chloroform, methanol, and sulfuric acid were not used, and no expensive analytical instruments were needed. We applied this method to Cupriavidus necator culture broths that included various amounts of poly(3-hydroxybutyrate) (PHB) or poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) from flasks and jar fermentors. The quantitation by this method was practical for use with a wide range of production amounts and PHA monomer compositions compared to the conventional whole-cell methanolysis method with gas chromatographic analysis, and besides, the recovered PHAs were adequately pure (≥96% purity). Therefore, this new method would be valuable not only for quantitation of PHA but also for preparation of samples to characterize their mechanical properties.





  • Intracellular Ca2+ is an essential factor for cell damage induced by unsaturated carbonyl compounds
    Publication date: Available online 25 July 2017
    Source:Journal of Bioscience and Bioengineering

    Author(s): Tsunehito Higashi, Yosuke Mai, Yuichi Mazaki, Soichi Miwa

    The unsaturated carbonyl compounds are known as the environmental pollutants. Acrolein (ACR) and methyl vinyl ketone (MVK) are representative unsaturated carbonyl compounds. ACR is contained in smoke, automobile exhaust, industrial waste, and several foods. MVK is widely used as the industrial chemical. Although ACR and MVK are highly toxic, the molecular mechanism for their cytotoxicity has been unclear. We have previously reported that ACR and MVK are major cytotoxic compounds in the gas phase of cigarette smoke, and protein kinase C (PKC) inhibitor and NADPH oxidases inhibitor partially rescued cells from ACR- or MVK-induced cell death (Noya et al., Toxicology, 314, 1–10, 2013). PKC translocation, which is hallmark for PKC activation, and cell damage were induced by treatment of cultured cells with ACR or MVK. Intracellular Ca2+ chelator completely suppressed ACR- or MVK-induced PKC translocation to the cell membrane and cell damage, while extracellular Ca2+ chelator had no effects on ACR- and MVK-induced cytotoxicity. These results suggest that intracellular Ca2+ is an essential factor for cell damage caused by both PKC-dependent and PKC-independent pathways, and mobilization of Ca2+ from intracellular Ca2+ stores is induced by ACR or MVK.





  • Isolation of six novel 7-oxo- or urso-type secondary bile acid-producing bacteria from rat cecal contents
    Publication date: Available online 24 July 2017
    Source:Journal of Bioscience and Bioengineering

    Author(s): Sarinya Tawthep, Satoru Fukiya, Ja-Young Lee, Masahito Hagio, Yoshitoshi Ogura, Tetsuya Hayashi, Atsushi Yokota

    Understanding the dynamics of secondary bile acid (SBA) formation in the gut by SBA-producing bacteria is important for host health, as SBAs have been shown to affect host pathophysiology and gut microbiota composition. However, our knowledge of SBA producers is limited in light of the diversity of gut microbes. Here, we isolated six novel SBA-producing bacteria from rat cecal contents, all of which were members of known species of gut microbes. Anaerostipes caccae D10, Bacteroides nordii C5, Clostridioides difficile D7, and Clostridium cadaveris G11 were capable of oxidizing cholic acid and chenodeoxycholic acid into 7-oxo-derivatives with varying yields. B. nordii C5 and its type strain JCM 12987T had the highest molar yield, ∼90%. Clostridium disporicum F4 and Clostridium subterminale C4 epimerized cholic acid into ursocholic acid with yields of ∼85%; the corresponding type strains lacked epimerization activity. Furthermore, although not novel as an SBA producer, Clostridium scindens G10 that produced deoxycholic acid from cholic acid was isolated for the first time from rodents. These findings will contribute to elucidation of SBA formation in the gut.