• Parasites, Hosts and Diseases
• /
• v.60 no.5
• /
• pp.345-352
• /
• 2022

Chitinase AO-801 is a hydrolase secreted by Arthrobotrys oligospora during nematode feeding, while its role remained elusive. This study analyzed the molecular characteristics of recombinant chitinase of Arthrobotrys oligospora (reAO-801). AO-801 belongs to the typical glycoside hydrolase 18 family with conserved chitinase sequence and tertiary structure of (α/β)₈ triose-phosphate isomerase (TIM) barrel. The molecular weight of reAO-801 was 42 kDa. reAO-801 effectively degraded colloidal and powdered chitin, egg lysate, and stage I larval lysate of Caenorhabditis elegans. The activity of reAO-801 reached its peak at 40℃ and pH values between 4-7. Enzyme activity was inhibited by Zn2⁺, Ca2⁺, and Fe3⁺, whereas Mg2⁺ and K⁺ potentiated its activity. In addition, urea, sodium dodecyl sulfate, and 2-mercaptoethanol significantly inhibited enzyme activity. reAO-801 showed complete nematicidal activity against C. elegans stage I larvae. reAO-801 broke down the C. elegans egg shells, causing them to die or die prematurely by hatching the eggs. It also invoked degradation of Haemonchus contortus eggs, resulting in apparent changes in the morphological structure. This study demonstrated the cytotoxic effect of reAO-801, which laid the foundation for further dissecting the mechanism of nematode infestation by A. oligospora.

• Geomechanics and Engineering
• /
• v.38 no.3
• /
• pp.307-317
• /
• 2024

To get a better understanding of the effect of drying-wetting cycles (DWC) on the mechanical behaviors of silty clay hiving different initial moisture content (IMC), the direct shear tests were performed on sliding band soil taken from a reservoirinduced landslide at the Three Gorges Reservoir area. The results indicated that, as the increasing number of DWC, the shear stress-displacement curves type changed from strain-hardening to strain-softening, and both the soil peak strengths and strength parameters reduced first and then nearly remain unchanged after a certain number of DWC. The effects of DWC on the cohesion were predominated that on the internal friction angle. The IMC of 17% is regarding as the critical moisture content, and the evolution laws of both peak shear strength and strength parameters presented a reversed 'U' type with the rising of the IMC. Based on it, a strength deterioration evolution model incorporating the influence of IMC and DWC was developed to describe the total degradation degree and degradation rate of strength parameters, and the degradation of strength parameters caused by DWC could be counterbalanced to some extent as the soil IMC close to critical moisture content. The microscopic mechanism for the soil strength caused by the IMC and DWC were discussed separately. The research results are of great significance for further understanding the water-weakening mechanicals of the silty clay subjected to the water absorption/desorption.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.1
• /
• pp.9-19
• /
• 2016

Xylanases sourced from different bacteria have significantly different enzymatic properties. Therefore, studying xylanases from different bacteria is important to their applications in different fields. A potential xylanase degradation gene in Massilia was recently discovered through genomic sequencing. However, its xylanase activity remains unexplored. This paper is the first to report a xylanase (XynRBM26) belonging to the glycosyl hydrolase family (GH10) from the genus Massilia. The gene encodes a 383-residue polypeptide (XynRBM26) with the highest identity of 62% with the endoxylanase from uncultured bacterium BLR13. The XynRBM26 expressed in Escherichia coli BL21 is a monomer with a molecular mass of 45.0 kDa. According to enzymatic characteristic analysis, pH 5.5 is the most appropriate for XynRBM26, which could maintain more than 90% activity between pH 5.0 and 8.0. Moreover, XynRBM26 is stable at 37℃ and could maintain at least 96% activity after being placed at 37℃ for 1 h. This paper is the first to report that GH10 xylanase in an animal gastrointestinal tract (GIT) has salt tolerance, which could maintain 86% activity in 5 M NaCl. Under the optimum conditions, K_m, V_max, and k_cat of XynRBM26 to beechwood xylan are 9.49 mg/ml, 65.79 μmol/min/mg, and 47.34 /sec, respectively. Considering that XynRBM26 comes from an animal GIT, this xylanase has potential application in feedstuff. Moreover, XynRBM26 is applicable to high-salt food and seafood processing, as well as other high-salt environmental biotechnological fields, because of its high catalytic activity in high-concentration NaCl.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.9
• /
• pp.1286-1294
• /
• 2015

The acute and subchronic toxicity of 1 kGy gamma-irradiated orange was evaluated in ICR mice. For acute toxicity, groups of 30 male and 30 female ICR mice were orally administered 1 kGy gamma-irradiated orange (0, 1,000, and 2,000 mg/kg). The mortality, clinical sign, body weight changes, and necropsy findings of ICR mice were observed for 14 days. No significant changes in body weight or abnormal gross findings were observed in relation to 1 kGy gamma-irradiated orange. Hematological and serum biochemical parameters were within normal ranges. According to the results, 1 kGy gamma-irradiated orange had no special toxic effects in male and female ICR mice at 2,000 mg/kg. For subchronic toxicity, groups of 36 male and 36 female ICR mice were given a diet of 1 kGy gamma-irradiated orange for 13 weeks (control, non-irradiated, and irradiated imported orange). During the experimental period, mortality, clinical signs, body weight change, food consumption, organ weight, and histopathological examination did not show any changes in comparison to the control group. Several hematological and serum biochemical parameters showed statistically significant changes, but these changes were within normal range. These results indicate that 1 kGy gamma-irradiated orange did not cause any toxic effects in male and female ICR mice and therefore can be considered as safe.

• Journal of Oriental Neuropsychiatry
• /
• v.20 no.3
• /
• pp.205-216
• /
• 2009

Objectives : To establish the fundaments for EBM of Traditional Korean Medicine, the papers on Guibi-tang(Guipitang) which were frequently used in medical institutions of Traditional Korean Medicine were analyzed through researching domestic and international literatures. Methods : The papers were classified by the year of publishment, by experimental methods, by laboratory animals used in biological experiment and by the kinds of studies on biological efficacy. Results : Of total 39 papers were registered in domestic journals. Since 1980, publishments of papers have continuously increased. The papers on biological studies were 34 volumes, clinical studies were 5 volumes. Biological studies mainly showed the effects of anti-stress, anti-oxidant, hemostasis, anti-osteoporosis, gastroprotection, reproductive ability, brain cell activity, radioprotection. And clinical studies showed improvements of fearful throbbing, memory and orientation, insomnia, vericose vein, schizophrenia. Conclusions : Guibi-tang(Guipitang) could be used to fortify the spleen, nourish the heart and then control the blood. However biological studies need to be conducted in accordance with clinical study and further clinical studies on randomized controlled trials should be proceeded.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.10
• /
• pp.1085-1091
• /
• 2009

A phytase with high activity at low temperatures has great potential for feed applications, especially in aquaculture. Therefore, this study used a degenerate PCR and TAIL PCR to clone a phytase gene from Erwinia carotovora var. carotovota, the cause of soft rot of vegetables in the ground or during cold storage. The full-length 2.5-kb fragment included an open reading frame of 1,302 bp and encoded a putative phytase of 45.3 kDa with a 50% amino acid identity to the Klebsiella pneumoniae phytase. The phytase contained the active site RHGXRXP and HD sequence motifs that are typical of histidine acid phosphatases. The enzyme was expressed in Escherichia coli, purified, and displayed the following characteristics: a high catalytic activity at low temperatures (retaining over 24% activity at $5^{\circ}C$) and remarkably thermal lability (losing >96% activity after incubation at $60^{\circ}C$ for 2 min). The optimal phytase activity occurred at pH 5.5 and ${\sim}49^{\circ}C$, and the enzyme activity rapidly decreased above $40^{\circ}C$. When compared with mesophilic counterparts, the phytase not only exhibited a high activity at a low temperature, but also had a low $K_m$ and high $k_{cat}$. These temperature characteristics and kinetic parameters are consistent with low-temperature-active enzymes. To our knowledge, this would appear to be the first report of a low-temperature-active phytase and its heterogeneous expression.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.11
• /
• pp.1944-1953
• /
• 2015

A novel alkaline protease from Streptomyces sp. M30, SapHM, was purified by ammonium sulfate precipitation, hydrophobic interaction chromatography, and DEAE-Sepharose chromatography, with a yield of 15.5% and a specific activity of 29,070 U/mg. Tryptic fragments of the purified SapHM were obtained by electrospray ionization quadrupole time-of-flight mass spectrometry. Nucleotide sequence analysis revealed that the gene sapHM contained 1,179 bp, corresponding to 392 amino acids with conserved Asp156, His187, and Ser339 residues of alkaline protease. The first 24 amino acid residues were predicted to be a signal peptide, and the molecular mass of the mature peptide was 37.1 kDa based on amino acid sequences and mass spectrometry. Pure SapHM was optimally active at 80℃ in 50 mM glycine-NaOH buffer (pH 9.0), and was broadly stable at 0-50℃ and pH 4.0-9.0. The protease relative activity was increased in the presence of Ni²⁺, Mn²⁺, and Cu²⁺ to 112%, 113%, and 147% of control, respectively. Pure SapHM was also activated by dimethylformamide, dimethyl sulfoxide, Tween 80, and urea. The activity of the purified enzyme was completely inhibited by phenylmethylsulfonyl fluoride, indicating that it is a serine-type protease. The K_m and V_max values were estimated to be 35.7 mg/ml, and 5 × 10⁴ U/mg for casein. Substrate specificity analysis showed that SapH was active on casein, bovine serum albumin, and bovine serum fibrin.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.12
• /
• pp.4951-4956
• /
• 2014

Purpose: To investigate IQGAP1 and IQGAP2 expression in hepatocellular carcinoma (HCC) and itsassociation with HCC clinicopathological characteristics and survival outcomes. Methods: IQGAP1 and IQGAP2 mRNA and protein were measured in HCC tissues, para-tumor tissues and normal tissues by RT-PCR and Western blotting. We further examined 150 HCC samples with adjacent para-tumor tissues and 11 normal specimens by immunohistochemistry to evaluate the correlation of IQGAP1 and IQGAP2 with clinicopathological features and prognosis. Results: IQGAP1 mRNA and protein were up-regulated while IQGAP2 mRNA and protein were down-regulated in human HCC tissues compared with para-tumor and normal liver tissues (p<0.05). IQGAP1 expression was higher in primary HCC (122/150, 81.3%) than matched adjacent tissues (30/150, 20%, p<0.001), whereas IQGAP2 was lower (31/150, 20.7% as compared to 112/150, 74.7%, P<0.001). Positive IQGAP1 expression correlated with larger tumor size (p=0.002), advanced TNM stage (p=0.002) and tumor differentiation (III and IV, p=0.034). Negative IQGAP2 expression was significantly associated with larger tumor size (p=0.009), multicentric tumor occurrence (p=0.01), advanced TNM stage (0.009) and tumor differentiation (III and IV, p=0.020). Survival analysis revealed that patients with either IQGAP1+ or IQGAP2-tumors had significantly reduced disease-free survival (p<0.001 and 0.006 respectively) and overall survival (p<0.001 for both). Multivariate analysis showed that IQGAP1/2 switch was an independent prognosis factor for disease-free survival (HR=2.824) and overall survival (HR=2.189). Conclusion: Positive IQGAP1 and negative IQGAP2 expression were closely correlated with tumor progression and could be used as adjunctive biomarkers to improve prognostication for HCC patients.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.11
• /
• pp.1532-1539
• /
• 2012

The ${\alpha}$-galactosidase-coding gene agaAJB13 was cloned from Sphingomonas sp. JB13 showing 16S rDNA (1,343 bp) identities of ${\leq}97.2%$ with other identified Sphingomonas strains. agaAJB13 (2,217 bp; 64.9% GC content) encodes a 738-residue polypeptide (AgaAJB13) with a calculated mass of 82.3 kDa. AgaAJB13 showed the highest identity of 61.4% with the putative glycosyl hydrolase family 36 ${\alpha}$-galactosidase from Granulicella mallensis MP5ACTX8 (EFI56085). AgaAJB13 also showed <37% identities with reported protease-resistant or Sphingomonas ${\alpha}$-galactosidases. A sequence analysis revealed different catalytic motifs between reported Sphingomonas ${\alpha}$-galactosidases (KXD and RXXXD) and AgaAJB13 (KWD and SDXXDXXXR). Recombinant AgaAJB13 (rAgaAJB13) was expressed in Escherichia coli BL21 (DE3). The purified rAgaAJB13 was characterized using p-nitrophenyl-${\alpha}$-D-galactopyranoside as the substrate and showed an apparent optimum at pH 5.0 and $60^{\circ}C$ and strong resistance to trypsin and proteinase K digestion. Compared with reported proteaseresistant ${\alpha}$-galactosidases showing thermolability at $50^{\circ}C$ or $60^{\circ}C$ and specific activities of <71 U/mg with or without protease treatments, rAgaAJB13 exhibited a better thermal stability (half-life of >60 min at $60^{\circ}C$) and higher specific activities (225.0-256.5 U/mg). These sequence and enzymatic properties suggest AgaAJB13 is the first identified and characterized Sphingomonas ${\alpha}$-galactosidase, and shows novel protease resistance with a potential value for basic research and industrial applications.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.10
• /
• pp.1588-1593
• /
• 2014

This study evaluated the genotoxic effects of 30 kGy of X-ray irradiation to four foods (chicken, egg powder, dried green onion, and black pepper). In bacterial reversion assay with Salmonella Typhimurium TA98, TA100, TA1535, and TA1537, the X-ray irradiated foods did not show a significantly increased number of revertant colonies in the presence or absence of the S9 metabolic activation system. In chromosomal aberration tests with Chinese hamster ovary (CHO) cells, the X-ray irradiated foods showed no increase in the frequency of chromosomal aberrations. In in vivo mouse micronucleus assay, the X-ray irradiated foods did not show any increase in the frequency of polychromatic erythrocytes with micronuclei. These results indicate that 30 kGy of X-ray irradiation to four foods (chicken, egg powder, dried green onion, and black pepper) showed no genotoxic effects under these experimental conditions.