Isolation and characterization of a bio-agent antagonistic to diatom, <i>Stephanodiscus hantzschii</i>

Kang, Y.-H.,Kim, J.-D.,Kim, B.-H.,Kong, D.-S.,Han, M.-S. Blackwell Science Ltd 2005 Journal of applied microbiology Vol.98 No.5

<P>Abstract</P><P>Aims: </P><P>Identification of bacterium HYK0203-SK02 and its lysis of <I>Stephanodiscus hantzschii</I>.</P><P>Methods and Results: </P><P>In an effort to identify a bio-agent capable of controlling <I>S. hantzschii</I> blooms, we used the algal lawn method to identify 76 bacteria in relevant water samples. Of these, the seven isolate showed algicidal activity against <I>S. hantzschii</I>; isolate HYK0203-SK02 exhibited the strongest algicidal activity, and was used for further analysis. 16S rDNA sequencing of this isolate allowed us to identify HYK0203-SK02 as a strain of <I>Pseudomonas putida</I> (99·2%). Growth of <I>S. hantzschii</I> was strongly suppressed by bacteria in all growth phases, with the strongest algicidal activity noted against diatoms in the exponential stage (5–18 days). Host range assays revealed that isolate HYK0203-SK02 also strongly inhibited the growth of <I>Microcystis aeruginosa</I>, but stimulated growth of the diatom <I>Cyclotella</I> sp., which has a similar structure to that of <I>S. hantzschii</I>. Biochemical assays revealed that the algicidal substance seemed to be localized in the cytoplasmic membrane of this newly identified algicidal bacterium.</P><P>Conclusion: </P><P>The algicidal bacteria <I>P. putida</I> HYK0203-SK02 caused cell lysis and death of not only diatom <I>S. hantzschii</I> but also cyanobacteria <I>M. aeruginosa</I>, dramatically. Algicidal substance might be located at the compartment of cytoplasmic membrane.</P><P>Significance and Impact of the Study: </P><P>Taken together, our results indicate that <I>P. putida</I> HYK0203-SK02 may be a potential bio-agent for future use in controlling freshwater diatomic blooms.</P>

Effects of external tidal field on the evolution of the outer regions of multi-mass star clusters

Lee, K. H.,Lee, H. M.,Sung, H. Blackwell Science Ltd 2006 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.367 No.2

<P>ABSTRACT</P><P>We present <I>N</I>-body simulations (including an initial mass function) of globular clusters in the Galaxy in order to study effects of the tidal field systematically on the properties of the outer parts of globular clusters. Using <SMALL>NBODY6</SMALL>, which correctly takes into account the two-body relaxation, we investigate the development of tidal tails of globular clusters in the Galactic tidal field. For simplicity, we have employed only the spherical components (bulge and halo) of the Galaxy, and ignored the effects of stellar evolution which could have been important in the very early phase of the cluster evolution. The total number of stars in our simulations is about 20 000, which is much smaller than the realistic number of stars. All simulations had been done for several orbital periods in order to understand the development of the tidal tails. In our scaled-down models, the relaxation time is sufficiently short to show the mass segregation effect, but we did not go far enough to see the core collapse, and the fraction of stars lost from the cluster at the end of the simulations is only ∼10 per cent. The radial distribution of extra-tidal stars can be described by a power law with a slope around −3 in surface density. The directions of tidal tails are determined by the orbits and locations of the clusters. We find that the length of tidal tails increases towards the apogalacticon and decreases towards the perigalacticon. This is an anti-correlation with the strength of the tidal field, caused by the fact that the time-scale for the stars to respond to the potential is similar to the orbital time-scale of the cluster. The escape of stars in the tidal tails towards the pericentre could be another reason for the decrease of the length of tidal tails. We find that the rotational angular velocity of tidally induced clusters shows quite different behaviour from that of initially rotating clusters.</P>

Blueshifted diffuse interstellar bands in the spectrum of HD 34078

Galazutdinov, G. A.,Manicò,, G.,Krełowski, J. Blackwell Science Ltd 2006 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.366 No.3

<P>ABSTRACT</P><P>In this paper, we report the very first observation of diffuse interstellar bands (DIBs) that, in the spectrum of HD 34078 (AE Aur), are blueshifted with respect to the normal position that they have in other objects, where the rest-wavelength velocity frame is determined using very sharp interstellar atomic lines or molecular features. Only reasonably narrow DIBs seemingly show this effect, which is absent in broader ones. The result is confirmed independently using three different spectrographs attached to two different telescopes.</P>

Involvement of 4-1BB (CD137)−4-1BBligand interaction in the modulation of CD4⁺ T cell-mediated inflammatory colitis

Maerten, P.,Kwon, B. S.,Shen, C.,De Hertogh, G.,Cadot, P.,Bullens, D. M. A.,Overbergh, L.,Mathieu, C.,Van Assche, G.,Geboes, K.,Rutgeerts, P.,Ceuppens, J. L. Blackwell Science Ltd 2006 Clinical and experimental immunology Vol.143 No.2

<P>Summary</P><P>4-1BB ligand (4-1BBL) expressed on antigen-presenting cells interacts with 4-1BB on activated T cells (especially CD8<SUP>+</SUP> cells) and co-stimulates the latter to secrete cytokines and to proliferate. The role of 4-1BB−4-1BBL interaction was studied here in a model of colitis based on naive CD4<SUP>+</SUP> T cell transfer to SCID mice, a disease model in which CD8 cells do not take part. We found that CD4<SUP>+</SUP> T cells from 4-1BB-deficient mice, after transfer in SCID mice, proliferated more rapidly compared to wild-type CD4<SUP>+</SUP> T cells. Mice reconstituted with naive CD4<SUP>+</SUP> T cells from 4-1BB-deficient mice developed colitis, however, with a mixed Th1/Th2 response, in contrast to the Th1-type response in mice reconstituted with wild-type naive CD4<SUP>+</SUP> T cells. Importantly, this altered cytokine response did not temper colitis severity. Although it has been reported previously that 4-1BB co-stimulation may contribute to regulatory T cell functioning, we found that CD4<SUP>+</SUP>CD25<SUP>+</SUP> regulatory T cells from 4-1BB-deficient mice were perfectly able to prevent naive CD4<SUP>+</SUP> T cell-induced colitis. In conclusion, our data provide evidence that 4-1BB−4-1BBL interaction modulates the effector CD4<SUP>+</SUP> T cell-driven immune response and cytokine production in experimental colitis without affecting regulatory T cell function.</P>

First report of Tomato spotted wilt virus (Tospovirus, Bunyaviridae) infecting Euphorbia eritrea and Asclepias curassavica in Liguria, Italy

Salomone, A.,Masenga, V.,Minuto, G.,Parodi, C.,Roggero, P. Blackwell Science Ltd 2003 Plant pathology Vol.52 No.6

CYP90C1 and CYP90D1 are involved in different steps in the brassinosteroid biosynthesis pathway in <i>Arabidopsis thaliana</i>

Kim, Gyung-Tae,Fujioka, Shozo,Kozuka, Toshiaki,Tax, Frans E.,Takatsuto, Suguru,Yoshida, Shigeo,Tsukaya, Hirokazu Blackwell Science Ltd 2005 The Plant journal Vol.41 No.5

<P>Summary</P><P>Brassinosteroids (BRs) are plant hormones that are essential for a wide range of developmental processes in plants. Many of the genes responsible for the early reactions in the biosynthesis of BRs have recently been identified. However, several genes for enzymes that catalyze late steps in the biosynthesis pathways of BRs remain to be identified, and only a few genes responsible for the reactions that produce bioactive BRs have been identified. We found that the <I>ROTUNDIFOLIA3</I> (<I>ROT3</I>) gene, encoding the enzyme CYP90C1, which was specifically involved in the regulation of leaf length in <I>Arabidopsis thaliana</I>, was required for the late steps in the BR biosynthesis pathway. ROT3 appears to be required for the conversion of typhasterol to castasterone, an activation step in the BR pathway. We also analyzed the gene most closely related to <I>ROT3</I>, <I>CYP90D1</I>, and found that double mutants for <I>ROT3</I> and <I>CYP90D1</I> had a severe dwarf phenotype, whereas <I>cyp90d1</I> single knockout mutants did not. BR profiling in these mutants revealed that CYP90D1 was also involved in BR biosynthesis pathways. <I>ROT3</I> and <I>CYP90D1</I> were expressed differentially in leaves of <I>A. thaliana</I>, and the mutants for these two genes differed in their defects in elongation of hypocotyls under light conditions. The expression of <I>CYP90D1</I> was strongly induced in leaf petioles in the dark. The results of the present study provide evidence that the two cytochrome P450s, CYP90C1 and CYP90D1, play distinct roles in organ-specific environmental regulation of the biosynthesis of BRs.</P>

Transcriptional regulation of the <i>Drosophila ANT</i> gene by the DRE/DREF system

Kim, Young Shin,Shin, Meong Joo,Yang, Dong Jin,Yamaguchi, Masamitsu,Park, So Young,Yoo, Mi Ae Blackwell Science Ltd 2007 Genes to cells Vol.12 No.5

<P>Adenine nucleotide translocase (ANT) is a crucial component in the maintenance of cellular energy homeostasis, as well as in the formation of the mitochondrial permeability transition pores. However, the molecular mechanisms regulating the expression of the <I>ANT</I> gene are poorly understood. In this study, we have identified three DNA replication-related elements (DRE; 5′-TATCGATA) in the 5′-flanking region of the <I>Drosophila ANT</I> (<I>dANT</I>) gene. Gel-mobility shift analyses revealed that all three of the DREs were recognized by the DRE-binding factor (DREF). The site-directed mutagenesis of these DRE sites induces a considerable reduction in the activity of the <I>dANT</I> gene promoter <I>in vitro</I>. Analyses with transgenic flies harboring a <I>dANT-lacZ</I> fusion gene bearing the wild-type or mutant DRE sites showed that the DRE sites were required for the expression of <I>dANT in vivo</I>. We determined that the over-expression or knockdown of DREF exerts a regulatory effect on the activity of the <I>dANT</I> promoter. In addition, we observed the collapse of mitochondrial membrane potential in the eye imaginal discs in which DREF was over-expressed. These results show that DRE/DREF is a crucial regulator of <I>dANT</I> gene expression, and also suggest the possibility that cross-talk may occur between the DRE/DREF system and mitochondrial functioning.</P>

<i>Chlamydia pneumoniae</i> infection enhances cellular proliferation and reduces steroid responsiveness of human peripheral blood mononuclear cells via a tumor necrosis factor-α-dependent pathway

Cho, YS.,Kim, T-B.,Lee, T-H.,Moon, K-A.,Lee, J.,Kim, Y-K.,Lee, K-Y.,Moon, H-B. Blackwell Science Ltd 2005 Clinical and experimental allergy Vol.35 No.12

<P>Summary</P><P>Background</P><P>Although epidemiological studies have found an association between <I>Chlamydia pneumoniae</I> infection and severe asthma, the causality and underlying mechanism are largely unknown. We hypothesized that <I>C. pneumoniae</I> infection increases the proliferation and enhances the survival of immune and inflammatory cells, resulting in reduced responsiveness to corticosteroids and suggesting that the underlying mechanism is related to a TNF-α-dependent pathway.</P><P>Methods</P><P>Human peripheral blood mononuclear cells (PBMCs) were cultured <I>in vitro</I> in the presence or absence of <I>C. pneumoniae</I> infection. Responsiveness to corticosteroids was assayed by adding dexamethasone, and the underlying mechanism was investigated by treating cells with infliximab that is a chimeric anti-TNF-α monoclonal antibody. Cellular proliferation and apoptosis was assessed by thymidine uptake and counting apoptotic cells using flow cytometry.</P><P>Results</P><P>Cellular proliferation was significantly higher in <I>C. pneumoniae</I>-infected PBMCs than in uninfected PBMCs, which is more prominent in Th2-dominant microenvironment. The anti-proliferative and pro-apoptotic effect of corticosteroid were significantly reduced in <I>C. pneumoniae</I>-infected PBMCs compared with uninfected PBMCs. The proliferative effect of <I>C. pneumoniae</I> infection and the reduced response to corticosteroid were effectively reversed by blocking the TNF-α pathway at least partially.</P><P>Conclusion</P><P><I>C. pneumoniae</I> infection enhanced the proliferation and survival of immune and inflammatory cells, resulting in steroid resistance. The reversal of these phenomena by the TNF-α inhibitor suggests that TNF-α may play an important role in the induction of steroid dependence or resistance. A TNF-α inhibitor may therefore be a candidate agent for managing steroid-dependent or -resistant severe asthma.</P>

Morphology and kinetics studies on cephalosporin C production by <i>Cephalosporium acremonium</i> M25 in a 30-l bioreactor using a mixture of inocula

Kim, J.H.,Lim, J.S.,Kim, C.H.,Kim, S.W. Blackwell Science Ltd 2005 Letters in applied microbiology Vol.40 No.5

<P>Abstract</P><P>Aims: </P><P>In this study, the relationship between morphology and cephalosporin C (CPC) production in a 30-l bioreactor culture of <I>Cephalosporium acremonium</I> M25 using a 3 : 7 seed mixture was investigated. In addition, the kinetic model was established and applied.</P><P>Methods and Results: </P><P>CPC production was performed in a 30-l bioreactor using a 3 : 7 seed mixture. It was recognized that a 3 : 7 seed mixture was able to reduce lag phase and enhance CPC production. The maximum CPC production and cell mass were 1·96 and 81·5 g l<SUP>−1</SUP> respectively. Through a morphology study by observation using image analysis, it was concluded that changes of morphological features predicted the progressive production of CPC and that a morphology study could be useful in monitoring the CPC fermentation by <I>C. acremonium</I> M25. In the kinetics study, a kinetic model of CPC fermentation was developed and applied. The proposed model could adequately describe the fermentation of <I>C. acremonium</I> M25 in a 30-l bioreactor.</P><P>Conclusions: </P><P>CPC productivity was improved by using a 3 : 7 seed mixture in a 30-1 bioreactor. The changes in morphological features showed a very similar tendency with CPC production. A kinetic model of CPC fermentation was successfully established.</P><P>Significance and Impact of the Study: </P><P>The results of the present study suggest that the use of a 3 : 7 seed mixture inocula has considerable possibilities for improving CPC productivity if applied to industrial scale fermentations. Through morphology and kinetics study, the kinetic model to describe the morphological differentiation and CPC production by <I>C. acremonium</I> M25 was established.</P>

Investigation of extended-spectrum &bgr;-lactamases produced by clinical isolates of Klebsiella pneumoniae and Escherichia coli in Korea

Jeong, S.H.,Bae, I.K.,Kwon, S.B.,Lee, J.H.,Jung, H.I.,Song, J.S.,Jeong, B.C.,Kim, S.-J.,Lee, S.H. Blackwell Science Ltd 2004 Letters in applied microbiology Vol.39 No.1

<P>Abstract</P><P>Aims: </P><p>Isolates obtained from various regions in Korea in 2002 were identified and their susceptibility to extended-spectrum cephalosporins, monobactams and/or cephamycins was studied along with any production of extended-spectrum <i>&bgr;</i>-lactamases (ESBLs).</p><P>Methods and Results: </P><p>Bacteria identified by the conventional techniques and Vitek GNI card were <i>Klebsiella pneumoniae</i> and <i>Escherichia coli</i>. Using disk diffusion and double-disk synergy tests, we found that 39·2% of strains produced ESBLs. About 52% of isolates transferred resistance to ceftazidime by conjugation. Banding patterns of PCR amplification with the designed primers showed that 837- and 259-bp fragments specific to <i>bla</i><SUB>TEM</SUB> genes were amplified in 63·3% of strains. 929- and 231-bp fragments (<i>bla</i><SUB>SHV</SUB>), 847- and 520-bp fragments (<i>bla</i><SUB>CMY</SUB>), 597- and 858-bp fragments (<i>bla</i><SUB>CTX-M</SUB>) were amplified in 61·5, 17·3 and 7·7% of strains respectively. About 51·9% of strains contained more than two types of <i>&bgr;</i>-lactamase genes. Especially, one strain contained <i>bla</i><SUB>TEM</SUB>, <i>bla</i><SUB>CMY</SUB> and <i>bla</i><SUB>CTX-M</SUB> genes.</p><P>Significance: </P><p>Resistance mechanisms to <i>&bgr;</i>-lactams, comprising mostly ESBL production, lead to the resistance against even recently developed <i>&bgr;</i>-lactams in enterobacteria, which is now a serious threat to antibiotic therapy. The high prevalence of <i>bla</i><SUB>CMY</SUB> genes and multidrug-resistant genes may also make therapeutic failure and lack of eradiation of these strains by extended-spectrum cephalosporins or cephamycins.</p>