Inactivation of Listeria monocytogenes in brine and saline by alternating high-voltage pulsed current

The inactivating efficiency of alternating high-voltage pulsed (AHVP) current was investigated in brine (20 w/v% NaCl) and saline (0.9 w/v% NaCl) inoculated with 1x 107 cells/ml of Listeria monocytogenes. AHVP current at 12 V with 1 pulse completely inactivated L. monocytogenes in brine within 3 ms, while the bacteria in saline were fully inactivated by 10-pulsed electric treatment at 12 V within the same time. Electron microscopic observation demonstrated substantial structural damage of electrically treated L. monocytogenes in brine. These results suggest that AHVP treatment would be effective for the rapid and complete inactivation of L. monocytogenes in brine or saline solution.     

Ruegeria arenilitoris sp. nov., isolated from the seashore sand around a seaweed farm

A Gram-negative, motile and rod-shaped bacterial strain, G-M8^T, which was isolated from seashore sand around a seaweed farm at Geoje island in South Korea, was characterized taxonomically. It grew optimally at 30–37 °C, at pH 7.0–8.0 and in presence of 2 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain G-M8^T joined the cluster comprising the type strains of Ruegeria atlantica and Ruegeria lacuscaerulensis, showing 97.5 % sequence similarity, by a bootstrap resampling value of 85.8 %. It exhibited 16S rRNA gene sequence similarity values of 95.4–96.7 % to the type strains of the other Ruegeria species. Strain G-M8^T exhibited the highest gyrB sequence similarity value (88.5 %) to the type strain of R. lacuscaerulensis. Strain G-M8^T contained Q-10 as the predominant ubiquinone and C_18:1 ω7c as the predominant fatty acid. The polar lipid profile of strain G-M8^T was similar to that of R. atlantica KCTC 12424^T. The DNA G+C content of strain G-M8^T was 64.6 mol% and its mean DNA–DNA relatedness values with R. atlantica KCTC 12424^T and R. lacuscaerulensis KCTC 2953^T were 18 ± 5.3 and 10 ± 3.6 %, respectively. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, demonstrated that strain G-M8^T is distinguished from other Ruegeria species. On the basis of the data presented, strain G-M8^T (=KCTC 23960^T = CCUG 62412^T) represents a novel species of the genus Ruegeria, for which the name Ruegeria arenilitoris sp. nov. is proposed.     

Discovery of potent inhibitors of receptor protein tyrosine phosphatase sigma through the structure-based virtual screening

Receptor protein tyrosine phosphatase sigma (PTPσ) has proved to be a promising target for the development of therapeutics for the treatment of neurological diseases. Here, we report the first example for a successful application of the structure-based virtual screening to identify the novel small-molecule inhibitors of PTPσ. These inhibitors revealed high potencies with the associated IC₅₀ values ranging from 0.1 to 1.3 μM and were also screened for having desirable physicochemical properties as a drug candidate. Therefore, they deserve consideration for further development by structure–activity relationship studies to develop therapeutics for neurological diseases. Structural features relevant to the stabilization of the newly identified inhibitors in the active site of PTPσ are discussed in detail.     

Efficient integration of short interspersed element-flanked foreign DNA via homologous recombination

We investigated whether mouse short interspersed elements (SINEs) could influence the recombination frequency of foreign DNA. Vectors harboring a reporter gene in combinations of SINEs B1 and/or B2 or a portion of long interspersed element-1 were prepared and tested in vitro by a colony assay using HC11 murine mammary epithelial cells and in vivo by microinjection into fertilized mouse eggs. In transfected HC11 cells, the number of colonies surviving G418 selection increased by 3.5-fold compared with control when the reporter was flanked by fused B1-B2 sequences. Similar results were obtained from microinjection study; in fetuses 11.5 days post coitum, transgene positives in control and SINE-flanked vectors were 16 and 53%, respectively. Individual B1- and B2-harboring vectors showed equivalent activities with each other, as determined by the colony assay (2.8-fold versus 3.2-fold compared with control). We determined the contribution of homologous recombination to the SINE-mediated increase in integration frequency through a polymerase chain reaction-based strategy; in more than half of embryos transgenes underwent homologous recombinations involving B1 sequences. These results demonstrate that the SINE sequences can increase the integration rate of foreign DNA and that such an increase is most likely due to the enhancement of homologous recombination.     

Differential effects of circadian typology on sleep-related symptoms,physical fatigue and psychological well-being in relation to resilience

Various physiological and psychological functions are influenced by circadian typology (CT), which was reported to be related to resilience. However, few studies have assessed the effects of CT in relation to resilience. The aim of the present study was to assess the influence of CT on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience. The present study included a total of 1794 healthy hospital employees, and they completed the Morningness–Eveningness Questionnaire, Connor–Davidson Resilience Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Fatigue Severity Scale, Hospital Anxiety and Depression Scale and World Health Organization Quality of Life Scale Abbreviated Version. Subjects with evening type showed lower sleep quality, more daytime sleepiness and physical fatigue than neither types and morning types. Additionally, evening types were more depressed and anxious and reported a poorer quality of life. CT was found to be a significant predictor of sleep quality, but CT was minimally associated with physical fatigue and psychological well-being in the regression analysis. Instead, resilience was substantially related to all of the variables measured. In conclusion, CT independently predicts sleep quality, but the effects of CT on physical fatigue and psychological well-being are negligible compared to those of resilience.     

Evaluation of a fosmid-clone-based microarray for comparative analysis of swine fecal metagenomes

Glass slide arrayed with fosmid clone DNAs generated from swine feces as probes were fabricated and used as a metagenome microarray (MGA). MGA appeared to be specific to their corresponding target genomic fragments. The detection limit was 10 ng of genomic DNA (ca. 10(6) bacterial cells) in the presence of 1000 ng of background DNA. Linear relationships between the signal intensity and the target DNA (20-100 ng) were observed (r ( 2 )=0.98). Application of MGA to the comparison of swine fecal metagenomes suggested that the microbial community composition of swine intestine could be dependent on the health state of swine.     

Highly pathogenic H5N1 influenza virus causes coagulopathy in chickens

Severe hemorrhage at multiple organs is frequently observed in chickens infected with highly pathogenic avian influenza (HPAI) A viruses. In this study we examined whether HPAI virus infection leads to coagulation disorder in chickens. Pathological examinations showed that the fibrin thrombi were formed in arterioles at the lung, associated with the viral antigens in endothelial cells of chickens infected intravenously with HPAI virus. Hematological analyses of peripheral blood collected from the chickens revealed that coagulopathy was initiated at early stage of infection when viral antigens were detected only in the endothelial cells and monocytes/macrophages. Furthermore, gene expression of the tissue factor, the main initiator of blood coagulation, was upregulated in the spleen, lung, and brain of HPAI virus-infected chickens. These results suggest that dysfunction of endothelial cells and monocytes/macrophages upon HPAI virus infection may induce hemostasis abnormalities represented by the excessive blood coagulation and consumptive coagulopathy in chickens.     

Regenerative ability of somatic single and multiple embryos from cotyledons of Korean ginseng on hormone-free medium

Cotyledon explants of Korean ginseng (Panax ginseng C. A. Meyer) produced somatic embryos directly on growth regulator-free medium. Somatic embryos developed as either multiple or single-state forms, depending on the degree of maturity of the cotyledons. Cotyledon explants from midmature zygotic embryos formed multiple embryos, while cotyledons from fully mature zygotic embryos formed single embryos. Somatic single embryos regenerated into normal plantlets with both roots and shoots, while multiple embryos did not produce roots but regenerated only into multiple shoots. In full-strength MS basal medium, the root growth of plantlets derived from single embryos was weak compared to that of shoots. Deletion of ammonium nitrate from the MS medium promoted the root growth of the plantlets. The ginseng plants with well-developed shoots and roots regenerated from single embryos were successfully acclimatized in a greenhouse when they were planted in soil. Received: 19 July 1997 / Revision received: 6 October 1997 / Accepted: 3 October 1997