A multiplex ligation detection assay for the characterization of Salmonella enterica strains

A proof of principle of a multi-target assay for genotyping Salmonella has been developed targeting 62 genomic marker sequences of Salmonella related to pathogenicity. The assay is based on multiplex ligation detection reaction (LDR) followed by customized ArrayTube? microarray detection. The feasibility of the developed assay was verified in a method comparison study with conventional PCR using 16 Salmonella 'test' strains comprising eight serovars. Subsequently, the feasibility of the LDR microarray assay was also tested by analyzing 41 strains belonging to 23 serovars. With the exception of four serovars each serovar was characterized by a unique virulence associated gene repertoire. The LDR microarray platform proved to be a convenient, rapid and easy to use tool with potential in tracing a Salmonella contamination in the food chain, for outbreak studies, and to provide data for risk assessors that support bio-traceability models.     

Optimal algorithms for dissemination of information in some interconnection networks

The problems of gossiping and broadcasting in one-way communication mode are considered for some prominent families of graphs. The complexity is measured as the number of communication rounds in the gossip and broadcast algorithms. The main result of the paper is the precise estimation of the gossip-problem complexity in cycles. To obtain this result a new combinatorial analysis of gossiping in cycles is developed. This analysis leads to an optimal lower bound on the number of rounds, and also to the design of an optimal algorithm for gossiping in cycles. The optimal algorithm for gossiping is later used to design new, effective algorithms for gossiping in important families of interconnection networks (cube connected cycles, butterfly networks). Furthermore, a new, effective algorithm for broadcasting in shuffle-exchange networks is developed.On leave from Comenius University, Bratislava, Czechoslovakia.     

Ein neues Maschinensystem für die Fixmaßbearbeitung in Großbetrieben

Ohne Zusammenfassung     

The LBA-problem and the deterministic tape complexity of two-way one-counter languages over a one-letter alphabet

Summary It is shown, that NTAPE(n) is equal to TAPE(n) if and only if every language L⊂⊣{1}^*⊢ which is acceptable by a nondeterministic two-way one-counter automaton whose counter length is bounded by the length of its input is contained in TAPE(log n).     

Comparison of biota-sediment accumulation factors across ecosystems

Sets of biota-sediment accumulation factors (BSAFs) for fish were compared across ecosystems for nonionic organic chemicals. The sets of BSAFs, when plotted against each other, in log-log space, formed linear relationships and demonstrated that the relative scaling or ranking of the individual BSAFs within a set are consistent, if not the same, across ecosystems. This behavior holds for chemicals that either are, or are not, metabolized by fish. These results demonstrate that sets of BSAF values can differ but with parallel shifts in magnitude between ecosystems (for example, all of the BSAFs in the set are uniformly larger in one ecosystem, while in another they all are uniformly smaller) in response to underlying differences in ecosystem conditions and parameters such as trophic level, diet of the organisms, and distribution of the chemical between the sediment and water column.     

Occurrence of a nitro metabolite of a defined nonylphenol isomer in soil/sewage sludge mixtures

Uniformly [14C]-ring-labeled 4-(3,5-dimethyl-3-heptyl)phenol (353-nonylphenol) is a highly relevant isomer of the technical nonylphenol mixture. We studied the sorption, desorption, and degradation of the synthesized isomer in an agricultural sandy loam at various soil/sewage sludge ratios. Sorption of 353-nonylphenol was high and differed with the amount of suspended soil in water. log Koc values, which are used to assess the risk of nonylphenol, ranged from 3.80 to 5.75. Desorption was slow and low and resulted in constant concentrations of about 15 ng/L353-nonylphenol in water after several desorption steps. In degradation studies up to 6% of the applied 353-nonylphenol in soil was volatilized; we consider this an important source of nonylphenol in the environment. With increasing amounts of sewage sludge in the soil/sewage sludge mixtures, 353-nonylphenol was stabilized, probably because of the lack of oxygen in sludge aggregates even under oxic conditions in flow-through systems. Unexpectedly, a less-polar metabolite was detected in amounts up to 40% of the applied nonylphenol after 135 days of incubation. This novel metabolite was identified as 4-(3,5-dimethyl-3-heptyl)-2-nitrophenol. This product formation might indicate the existence of novel metabolic pathways of nonylphenol in the environment.