Characteristics of cold-adaptive endochitinase from Antarctic bacterium Sanguibacter antarcticus KOPRI 21702

The psychrotrophic Sanguibacter antarcticus KOPRI 21702^T, isolated from Antarctic seawater, produced a cold-adapted chitinolytic enzyme that is a new 55 kDa family 18 chitinase (Chi21702). Chi21702 exhibited high activities toward pNP-(GlcNAc)₂ and pNP-(GlcNAc)₃ with no activity for pNP-GlcNAc, indicating that it prefers chitin chains longer than dimers, just as endochitinases do. A mixture of GlcNAc and GlcNAc₂ was produced as a main product by Chi21702 activity from chitin oligosaccharides and swollen chitin, while less GlcNAc₃ was produced. These results show that Chi21702 has an endochitinase activity, randomly hydrolyzing chitin at internal sites. Chi21702 displayed chitinase activity at 0–40 °C (optimal temperature of 37 °C), maintained its activity at pH 4–11 (optimal pH of 7.6). Interestingly, Chi21702 exhibited relative activities of 40% and 60% at 0 and 10 °C, respectively, in comparison to 100% at 37 °C, which is higher than those of the previously characterized, cold-adapted, chitinases from bacterial strains.     

Introducing pulsed low-intensity ultrasound to culturing human umbilical cord-derived mesenchymal stem cells

The human umbilical cord (hUC) is a source of adult tissue-derived mesenchymal stem cells (MSCs). A pulsed low-intensity ultrasound (PLIUS) method is described for increasing the yield of MSCs from whole hUC without enzymatic digestion or growth factor supplementation. Analysis of the immunophenotype of cells and a differentiation study were performed to show the compatibility of MSCs. The mean number of cells recovered from primocultures of hUC was 6 × 10⁵ cells/cm. PLIUS resulted in a 3.3-fold increase in MSC yield at passage 0. PLIUS exposure increases the yield of hUC-MSCs by promoting release and enhancing proliferation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Metabolic profiles of genetically modified potatoes using a combination of metabolite fingerprinting and multivariate analysis

Comprehensive metabolite fingerprinting of transgenic potatoes that constitutively express human beta amyloid, curdlan synthase (CRDS), and glycogen synthase (glgA); and of wild-type potatoes was carried out using FT-IR and ¹H NMR spectroscopy in combination with multivariate analyses. Comparison of metabolic patterns between transgenic and wild-type potatoes revealed that there were neither quantitative nor qualitative differences in metabolites between transgenic potatoes expressing human beta amyloid, CRDS or glgA, and non-transformed control potatoes. However, there were metabolic differences between two control potato lines — one that was fresh and the other stored. After 1 week of storage, comprehensive metabolite patterns were significantly modified. Although the differences between CRDS and glgA transgenic and control potato lines were small, PCA analysis of FT-IR and ¹H NMR spectral data identified two distinct control lines. These results suggest that the comprehensive metabolite changes in control potato lines, which occurred after 1 week of storage, were greater than the differences between CRDS and glgA transgenic and wild-type potato lines. Thus, the combination of FT-IR and ¹H NMR spectral data and multivariate analysis was valuable for the detection of comprehensive differences in metabolic profiles between transgenic and non-transformed control plants, even though peak-signal overlap prevented assignment of pure compounds. The combination of FT-IR and ¹H NMR spectral data and multivariate analysis is a simple and rapid method for evaluation of the metabolic equivalence of GM crops.     

Purification and identification of an angiotensin I-converting enzyme inhibitory peptide from fermented soybean extract

Angiotensin I-converting enzyme (ACE), a dipeptidyl carboxypeptidase, plays an important physiological role in regulating blood pressure. ACE-inhibitory peptides derived from food proteins have potential pharmaceutical and human health uses. In this study, we prepared a fermented soybean extract (FSE) through a rapid fermentation at an elevated temperature to accelerate proteolytic hydrolysis and described purification procedures to discover potent ACE-inhibitory peptides from FSE. After 3 days of aging, FSE exhibited ACE-inhibitory activity with an IC₅₀ value of 1.46 mg/mL. Purification of novel ACE-inhibitory peptides was carried out using ultrafiltration and consecutive chromatographic methods. A novel ACE-inhibitory peptide, with 66-fold increase in ACE-inhibitory activity compared to that of FSE, was isolated from FSE through a five-step purification procedure. The amino acid sequence of the purified ACE-inhibitory peptides was determined to be Leu-Val-Gln-Gly-Ser by Edman degradation method, and its IC₅₀ value was 22 μg/mL (43.7 μM).     

Autonomous zinc-finger nuclease pairs for targeted chromosomal deletion

Zinc-finger nucleases (ZFNs) have been successfully used for rational genome engineering in a variety of cell types and organisms. ZFNs consist of a non-specific FokI endonuclease domain and a specific zinc-finger DNA-binding domain. Because the catalytic domain must dimerize to become active, two ZFN subunits are typically assembled at the cleavage site. The generation of obligate heterodimeric ZFNs was shown to significantly reduce ZFN-associated cytotoxicity in single-site genome editing strategies. To further expand the application range of ZFNs, we employed a combination of in silico protein modeling, in vitro cleavage assays, and in vivo recombination assays to identify autonomous ZFN pairs that lack cross-reactivity between each other. In the context of ZFNs designed to recognize two adjacent sites in the human HOXB13 locus, we demonstrate that two autonomous ZFN pairs can be directed simultaneously to two different sites to induce a chromosomal deletion in ∼10% of alleles. Notably, the autonomous ZFN pair induced a targeted chromosomal deletion with the same efficacy as previously published obligate heterodimeric ZFNs but with significantly less toxicity. These results demonstrate that autonomous ZFNs will prove useful in targeted genome engineering approaches wherever an application requires the expression of two distinct ZFN pairs.     

Atrial local Ca signaling and inositol 1,4,5-trisphosphate receptors

In atrial myocytes lacking t-tubules, action potential triggers junctional Ca²⁺ releases in the cell periphery, which propagates into the cell interior. The present article describes growing evidence on atrial local Ca²⁺ signaling and on the functions of inositol 1,4,5-trisphosphate receptors (IP₃Rs) in atrial myocytes, and show our new findings on the role of IP₃R subtype in the regulation of spontaneous focal Ca²⁺ releases in the compartmentalized areas of atrial myocytes. The Ca²⁺ sparks, representing focal Ca²⁺ releases from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RyR) clusters, occur most frequently at the peripheral junctions in isolated resting atrial cells. The Ca²⁺ sparks that were darker and longer lasting than peripheral and non-junctional (central) sparks, were found at peri-nuclear sites in rat atrial myocytes. Peri-nuclear sparks occurred more frequently than central sparks. Atrial cells express larger amounts of IP₃Rs compared with ventricular cells and possess significant levels of type 1 IP₃R (IP₃R1) and type 2 IP₃R (IP₃R2). Over the last decade the roles of atrial IP₃R on the enhancement of Ca²⁺-induced Ca²⁺ release and arrhythmic Ca²⁺ releases under hormonal stimulations have been well documented. Using protein knock-down method and confocal Ca²⁺ imaging in conjunction with immunocytochemistry in the adult atrial cell line HL-1, we could demonstrate a role of IP₃R1 in the maintenance of peri-nuclear and non-junctional Ca²⁺ sparks via stimulating a posttranslational organization of RyR clusters.     

Multiplex PCR detection of waterborne intestinal protozoa: microsporidia, Cyclospora, and Cryptosporidium

Recently, emerging waterborne protozoa, such as microsporidia, Cyclospora, and Cryptosporidium, have become a challenge to human health worldwide. Rapid, simple, and economical detection methods for these major waterborne protozoa in environmental and clinical samples are necessary to control infection and improve public health. In the present study, we developed a multiplex PCR test that is able to detect all these 3 major waterborne protozoa at the same time. Detection limits of the multiplex PCR method ranged from 10(1) to 10(2) oocysts or spores. The primers for microsporidia or Cryptosporidium used in this study can detect both Enterocytozoon bieneusi and Encephalitozoon intestinalis, or both Cryptosporidium hominis and Cryptosporidium parvum, respectively. Restriction enzyme digestion of PCR products with BsaBI or BsiEI makes it possible to distinguish the 2 species of microsporidia or Cryptosporidium, respectively. This simple, rapid, and cost-effective multiplex PCR method will be useful for detecting outbreaks or sporadic cases of waterborne protozoa infections.     

Zinc(II) ion mediates tamoxifen-induced autophagy and cell death in MCF-7 breast cancer cell line

Treatment of MCF-7 cells with tamoxifen induced vacuole formation and cell death. Levels of the autophagy marker, microtubule-associated protein light chain 3 (LC3)-II also increased, and GFP-LC3 accumulated in and around vacuoles in MCF-7 cells exposed to tamoxifen, indicating that autophagy is involved in tamoxifen-induced changes. Live-cell confocal microscopy with FluoZin-3 staining and transmission electron microscopy with autometallographic staining revealed that labile zinc(II) ion (Zn²⁺) accumulated in most acidic LC3(+) autophagic vacuoles (AVs). Chelation of Zn²⁺ with N,N,N′,N′-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN) blocked the increase in phospho-Erk and LC3-II levels, and attenuated AV formation and cell death. Conversely, the addition of ZnCl₂ markedly potentiated tamoxifen-induced extracellular signal-regulated kinase (Erk) activation, autophagy and cell death, indicating that Zn²⁺ has an important role in these events. Tamoxifen-induced death was accompanied by increased oxidative stress and lysosomal membrane permeabilization (LMP) represented as release of lysosomal cathepsins into cytosol. Treatment with the antioxidant N-acetyl-l-cysteine (NAC) blunted the increase in Zn²⁺ levels and reduced LC3-II conversion, cathepsin D release and cell death induced by tamoxifen. And cathepsin inhibitors attenuated cell death, indicating that LMP contributes to tamoxifen-induced cell death. Moreover, TPEN blocked tamoxifen-induced cathepsin D release and increase in oxidative stress. The present results indicate that Zn²⁺ contributes to tamoxifen-induced autophagic cell death via increase in oxidative stress and induction of LMP.