Wyniki wyszukiwania - Biblioteka Nauki

1

Differentiated Paju cells have increased resistance to toxic effects of potassium ionophores.

100%

Teplova V. , Jääskeläinen E. , Salkinoja-Salonen M. , Saris N.-E. L. , Serlachius M. , Li F.-Y. , Andersson L. C.

Acta Biochimica Polonica

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2004

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tom 51

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nr 2

539-544

EN

In this study we have investigated the impact of differentiation of neuronal cells on their sensitivity to microbial toxins. We used the human neural crest-derived tumor cell line Paju, which can be induced to differentiation in vitro by treatment with phorbol 12-myristate 13-acetate. Addition of the highly toxic potassium ionophores cereulide (4.5 and 9.0 ng/ml) or valinomycin (20 ng/ml), to cultures of undifferentiated Paju cells caused collapse of the mitochondrial membrane potential - measured with the fluorescent probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetrabenzimidazole carbocyanine iodide (JC-1) followed by detachment of the cells and their apoptotic death. After induced differentiation of the Paju cells, their mitochondria retained the membrane potential upon exposure to the toxins and the cells displayed increased resistance to apoptosis as compared with undifferentiated cells. This effect may be caused by an elevated expression of the anti-apoptotic protein Bcl-2 and of the neuroprotective factor, stanniocalcin, in differentiated cells.

2

PCR-based DNA test for detection of emetic Bacillus cereus strains producing cereulide

100%

Oltuszak-Walczak E. , Walczak P.

Polish Journal of Food and Nutrition Sciences

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2007

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tom 57

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nr 3[A]

EN

Two PCR-based methods for identification of emetic toxin producing Bacillus cereus strains were developed. The first set of primers cesBF and cesBR allowed for the amplification of cesBI 838 bp long fragment of cereulide biosynthesis operon for cereulide producing strains, or 421 bp long fragment of nonribosomal peptide synthetase (nrps) for emetic toxin non producing strains. Detection of both genes cesBI and nrps was possible in one PCR reaction. Among 24 strains of Cereus group tested, only one named 19W-cesB contained cesBI gene fragment. Bacillus cereus isolate 19W-cesB did not contain of any other genes of nonribosomal peptide synthetases responsible for the synthesis of other low molecular weight peptide toxins. The shdR and shdF second primer set allowed for specific amplification of the other 690 bp long fragment of cesBII gene. Only strain 19W-cesB allowed for the PCR synthesis of appropriate amplicon from all tested strains. Proposed methods may be fast and reliable techniques for detection of Bacillus cereus strains producing cereulide.

PL

Opracowano dwie metody identyfikacji szczepów Bacillus cereus wytwarzających toksynę wymiotną cereulid, bazujące na reakcji PCR. Pierwszy zestaw starterów cesBF i cesBR pozwalał na amplifikację fragmentu genu cesBI o długości 838 pz dla szczepów zawierających operon biosyntezy cereulidu lub fragmentu genów nierybosomalnej syntetazy peptydowej (nrps) o długości 421 pz dla szczepów nie wytwarzających toksyny wymiotnej. W jednej reakcji PCR możliwa była detekcja genów biosyntezy cereulidu jak i genów biosyntezy innych cyklicznych peptydów (nrps). Spośród 24 przebadanych szczepów grupy Cereus wykazano jedynie u szczepu 19W-cesB obecność genu cesB. Stwierdzono również, że szczep wytwarzający toksynę wymiotną nie zawierał innych genów nierybosomalnych syntetaz peptydowych. Drugi zestaw primerów, shdR i shdF pozwalał na bardzo specyficzną amplifikację innego fragmentu genu cesBII o długości 690 pz gdyż spośród 24 szczepów, jedynie dla szczepu 19W-cesB otrzymano charakterystyczny amplikon. Zaproponowane metody pozwalają na szybką i prostą diagnostykę szczepów potencjalnych producentów toksyny wymiotnej.

3

Cereulide and valinomycin, two important natural dodecadepsipeptides with ionophoretic activities

84%

Kroten M. A. , Bartoszewicz M. , Swiecicka I.

Polish Journal of Microbiology

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2010

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tom 59

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nr 1

3-10

EN

Cereulide produced by Bacillus cereus sensu stricto and valinomycin synthesized mainly by Streptomyces spp. are natural dodecadepsipeptide ionophores that act as potassium transporters. Moreover, they comprise three repetitions of similar tetrapeptide motifs synthesized by non-ribosomal peptide synthesis complexes. Resemblances in their structure find their reflections in the same way of action. The toxicity of valinomycin and cereulide is an effect of the disturbance of ionic equilibrium and transmembrane potential that may influence the whole organism and then cause fatal consequences. The vim and ces operons encoding valinomycin and cereulide are both composed of two large, similar synthetase genes, one thioestrase gene and four other ORFs with unknown activities. In spite of the characterization of valinomycin and cereulide, genetic determinants encoding their biosynthesis have not yet been clarified.

4

Differentiated Paju cells have increased resistance to toxic effects of potassium ionophores

84%

Teplova V. , Jaaskelainen E. , Salkinoja-Salonen M. , Saris N. E. L. , Serlachius M. , Li F. Y. , Andersson L. C.

Acta Biochimica Polonica

|

2004

|

tom 51

|

nr 2

EN

In this study we have investigated the impact of differentiation of neuronal cells on their sensitivity to microbial toxins. We used the human neural crest-derived tumor cell line Paju, which can be induced to differentiation in vitro by treatment with phorbol 12-myristate 13-acetate. Addition of the highly toxic potassium ionophores cereulide (4.5 and 9.0 ng/ml) or valinomycin (20 ng/ml), to cultures of undifferentiated Paju cells caused collapse of the mitochondrial membrane potential — measured with the fluorescent probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetrabenzimidazole carbo- cyanine iodide (JC-1) followed by detachment of the cells and their apoptotic death. After induced differentiation of the Paju cells, their mitochondria retained the membrane potential upon exposure to the toxins and the cells displayed increased resistance to apoptosis as compared with undifferentiated cells. This effect may be caused by an elevated expression of the anti-apoptotic protein Bcl-2 and of the neuroprotective factor, stanniocalcin, in differentiated cells.