A fission yeast homolog of Int-6, the mammalian oncoprotein and eIF3 subunit, induces drug resistance when overexpressed.

Through a screen to identify genes that induce multi-drug resistance when overexpressed, we have identified a fission yeast homolog of Int-6, a component of the human translation initiation factor eIF3. Disruption of the murine Int-6 gene by mouse mammary tumor virus (MMTV) has been implicated previously in tumorigenesis, although the underlying mechanism is not yet understood. Fission yeast Int6 was shown to interact with other presumptive components of eIF3 in vivo, and was present in size fractions consistent with its incorporation into a 43S translation preinitiation complex.

Habituation of Salmonella spp. at reduced water activity and its effect on heat tolerance.

The effect of habituation at reduced water activity (a(w)) on heat tolerance of Salmonella spp. was investigated. Stationary-phase cells were exposed to a(w) 0.

The role of SEF14 and SEF17 fimbriae in the adherence of Salmonella enterica serotype Enteritidis to inanimate surfaces.

To gain an understanding of the role of fimbriae and flagella in the adherence of Salmonella enterica serotype Enteritidis to inanimate surfaces, the extent of adherence of viable wild-type strains to a polystyrene microtitration plate was determined by a crystal violet staining assay. Elaboration of surface antigens by adherent bacteria was assayed by fimbriae- and flagella-specific ELISAs. Wild-type Enteritidis strains adhered well at 37 degrees C and 25 degrees C when grown in microtitration wells in Colonisation Factor Antigen broth, but not in other media tested.

Survival and filamentation of Salmonella enterica serovar enteritidis PT4 and Salmonella enterica serovar typhimurium DT104 at low water activity.

In this study we investigated the long-term survival of and morphological changes in Salmonella strains at low water activity (a(w)). Salmonella enterica serovar Enteritidis PT4 and Salmonella enterica serovar Typhimurium DT104 survived at low a(w) for long periods, but minimum humectant concentrations of 8% NaCl (a(w), 0. 95), 96% sucrose (a(w), 0.

The effectiveness of hygiene procedures for prevention of cross-contamination from chicken carcases in the domestic kitchen.

Thirteen sites in each of 60 domestic kitchens were examined for Salmonella and Campylobacter spp. following the preparation of a chicken for cooking and the application of different hygiene regimes. During food preparation bacteria became widely disseminated to hand and food contact surfaces.

Experimental tunneling ratchets.

Adiabatically rocked electron ratchets, defined by quantum confinement in semiconductor heterostructures, were experimentally studied in a regime where tunneling contributed to the particle flow. The rocking-induced electron flow reverses direction as a function of temperature. This result confirms a recent prediction of fundamentally different behavior of classical versus quantum ratchets.

Isolation of sublethally injured campylobacters from poultry and water sources.

Campylobacters are the most common cause of bacterial food poisoning in the UK and are prominent in many other countries worldwide. Sources that have acted as vehicles of infection in many outbreaks include milk, water and poultry, and these may contain campylobacter cells that are sublethally injured and not detected by routine laboratory techniques. Current culture media contain antibiotics to suppress competing flora, and injured campylobacter cells are more sensitive to the antibiotics used and may not grow in these selective media.

Survival of Escherichia coli O157 in a soil protozoan: implications for disease.

Intra-protozoal growth of bacterial pathogens has been associated with increased environmental survival, virulence and resistance to biocides and antibiotics. Using laboratory microcosms we have shown that Escherichia coli O157 survives and replicates in a common environmental protozoan, Acanthamoeba polyphaga. As protozoa are widely distributed in soils and effluents, they may constitute an important environmental reservoir for transmission of E.

Presence of Campylobacter and Salmonella in sand from bathing beaches.

The purpose of this study was to determine the presence of thermophilic Campylobacter spp. and Salmonella spp. in sand from non-EEC standard and EEC standard designated beaches in different locations in the UK and to assess if potentially pathogenic strains were present.

Aerosol route enhances the contamination of intact eggs and muscle of experimentally infected laying hens by Salmonella typhimurium DT104.

Commercial laying hens were infected with Salmonella typhimurium DT104 strain 16 alternatively via the crop (10(7) cfu per bird) or by an aerosol delivered directly to the beaks using a Collison nebuliser and Henderson apparatus (2 x 10(2) or 2 x 10(4) cfu per bird). Infection by both routes caused systemic infection and prolonged contamination of faeces. Contamination rates of eggs and muscle were much higher following the aerosol challenges despite the much lower doses given by this route.

Properties of an L-glutamate-induced acid tolerance response which involves the functioning of extracellular induction components.

Escherichia coli became more acid tolerant following incubation for 60 min in a medium containing L-glutamate at pH 7.0, 7.5 or 8.

Suppressors of cdc25p overexpression identify two pathways that influence the G2/M checkpoint in fission yeast.

Checkpoints maintain the order of cell-cycle events. At G2/M, a checkpoint blocks mitosis in response to damaged or unreplicated DNA. There are significant differences in the checkpoint responses to damaged DNA and unreplicated DNA, although many of the same genes are involved in both responses.

Pathogenicity in isolates of Salmonella enterica serotype Enteritidis PT4 which differ in RpoS expression: effects of growth phase and low temperature.

Experiments with 2 wild type isolates of Salmonella enterica serotype Enteritidis PT4, which differed in RpoS expression, tolerance to certain hostile environments and pathogenicity, found that changes in in vitro acid, heat, or peroxide tolerance had no effect on the ability of the isolates to multiply in the spleens of C57/BL7/J mice infected orally. Thus, with the pathogenic RpoS-positive isolate, the infectivity of log phase chilled cells, which are profoundly acid-sensitive, was the same as that of non-chilled stationary phase cells which are acid-tolerant. Similarity the infectivity of the RpoS-negative, sensitive isolate, was not enhanced by increases in any tolerance.

Cell-division-cycle defects associated with fission yeast pre-mRNA splicing mutants.

We have isolated six new pre-mRNA splicing mutants (prp) from a collection of temperature-sensitive (ts-) Schizosaccharomyces pombe strains. The prp mutants are defective in the splicing of both messenger RNA and U6 small nuclear RNA precursors. A single recessive mutation is responsible for both the ts- growth and the splicing phenotypes in each of the prp mutants.

Chilling invokes different morphologies in two Salmonella enteritidis PT4 strains.

The reduction in chemical preservatives in food processing has resulted in more refrigerated (chilled) products. However, the effect of chilling on Salmonella enteritidis PT4 isolates has received relatively little attention. This study investigates the effect of chilling on two Salm.

Sum1, a highly conserved WD-repeat protein, suppresses S-M checkpoint mutants and inhibits the osmotic stress cell cycle response in fission yeast.

The S-M checkpoint ensures that entry into mitosis is dependent on completion of DNA replication. In the fission yeast Schizosaccharomyces pombe, the SM checkpoint mutant cdc2-3w is thought to be defective in receiving the checkpoint signal. To isolate genes that function in the checkpoint pathway, we screened an S.

Discrimination of strains of Salmonella enteritidis with differing levels of virulence by an in vitro glass adherence test.

The objective of this study was the in vitro differentiation of isolates of Salmonella enteritidis whose virulences differed in a chick model. A total of 14 strains of S. enteritidis were isolated from either the environment, dairy products, or infected patients.

Heat tolerance of Salmonella typhimurium DT104 isolates attached to muscle tissue.

Eight separate experiments were performed with three isolates of Salmonella typhimurium DT104 to examine the impact that attachment to pork muscle tissue has on heat tolerance. In five experiments, attachment to muscle increased heat tolerance. For example, in one experiment the D (58 degrees C) value increased from approximately 2 min for free cells, to > 10 min for attached cells.

The use of an automated growth analyser to measure recovery times of single heat-injured Salmonella cells.

A new approach to the study of recovery times of single heat-injured Salmonella cells is described. It comprises the generation of a standard heat-injured culture, serial dilution of this culture to near extinction, inoculation of the serial dilutions across many microtitre plates and measurement of the subsequent recovery and growth using an automated turbidometric analyser. Lag times for individual cells were estimated from turbidity data using a model that accurately extrapolated the growth curve back to the starting inoculum level.

The cross-contamination and survival of Salmonella enteritidis PT4 on sterile and non-sterile foodstuffs.

The ability of two strains of Salmonella enteritidis PT4 to cross-contaminate from inoculated egg droplets on surfaces onto melon or beef (sterile or non-sterile) was investigated. When the foods were placed on these surfaces where egg droplets were still wet, cross-contamination occurred within 1 s onto every piece of food. It took at least 1 min for all the food pieces to be contaminated when egg droplets had been allowed to dry.

Induction of the PhoE porin by NaCl as the basis for salt-induced acid sensitivity in Escherichia coli.

Organisms grown in low salt broth (LSB) are acid resistant but become sensitive on growth for 30-60 min with 300 mmol l-1 added NaCl. Salt-induced acid sensitivity only occurs in relA+ strains and sensitization is abolished by glucose, this catabolite repression effect being reversed by cAMP. The finding that sensitization did not occur in a phoE strain but did occur in a phoE+ derivative of it suggested that the response might result from PhoE induction, since PhoE acts as the major outer membrane (OM) proton pore under most conditions.

Isolates of Salmonella enterica Enteritidis PT4 with enhanced heat and acid tolerance are more virulent in mice and more invasive in chickens.

Two Enteritidis PT4 isolates which differed in inherent tolerance to heat, acid, H2O2 and the ability to survive on surfaces were used to infect mice, day-old chicks or laying hens. The acid-, heat-, H2O2- and surface-tolerant isolate was more virulent in mice and more invasive in laying hens, particularly in reproductive tissue. However, no significant differences were observed in behaviour in chicks.