Comparative genomics of multiple plasmids from APEC associated with clonal outbreaks demonstrates major similarities and identifies several potential vaccine-targets

Avian pathogenic Escherichia coli (APEC) is associated with several types of extraintestinal infections, collectively known as colibacillosis. A heterogeneous population structure has hindered development of vaccines protective against all APEC. Recently, however, the existence of different APEC subpathotypes have been suggested, which are defined by specific disease syndromes and associated virulence genes. A collection of 14 APEC isolates representing clonal outbreaks of salpingitis accompanied by peritonitis and sepsis were characterized in the present study. All the strains carried large plasmids and the aim of the study was to investigate the similarity of these by sequencing, annotating and comparative analysis to identify potential vaccine targets. In addition, a comparison with gene content of human extraintestinal E. coli (ExPEC) subtypes was conducted. Results obtained demonstrated highly similar plasmid contents of the 14 APEC strains, despite the diversity of their chromosomal background. All 14 APEC carried the colicin V operon and numerous virulence genes. These included iss, traT, hlyF, eitABC, ompT, iroBCDEN, sitABCD, iutA and lucABCD. Several of these are shared with human ExPEC, implicating a possible zoonotic potential. Despite a diverse chromosomal background, it was concluded that the plasmid content of virulence genes are highly similar for the investigated APEC subpathotype. Based on their frequency, protein uniformity and subcellular localization iroN, iutA, iss, traT, ompT and etsC are suggested as vaccine-candidates. Experimental studies are, however, necessary to determine the protective potential of the candidates against the APEC subpathotype characterized by salpingitis, peritonitis and possibly septicaemia.     

Model studies on acrylamide generation from glucose/asparagine in aqueous glycerol

Acrylamide formation from asparagine and glucose in different ratios in neutral glycerol/water mixtures was found to increase with decreasing water activity (0.33 < or = aw < or = 0.71 investigated) and increasing temperature (120 degrees C < or = T < or = 160 degrees C investigated). The initial rate of acrylamide formation was found to be approximately proportional to the asparagine concentration for an excess of asparagine, but less dependent on an excess of glucose. A steady-state concentration of acrylamide was established at 160 degrees C after 1 h for aw = 0.33 (30 microg x L-1 for GLU:ASN = 10:1, 11 microg x L-1 for GLU:ASN = 1:1, and 130 microg x L-1 for GLU:ASN = 1:10) and for aw = 0.47 (15 microg x L-1 for GLU:ASN = 10:1 and 80 microg x L-1 for GLU:ASN = 1:10), suggesting a protection by glucose against acrylamide degradation. The energy of activation, as estimated from the temperature dependence of the initial rate, increased with decreasing aw despite a higher rate of formation of acrylamide at low aw. For high aw, water elimination from a reaction intermediate is suggested to be rate determining. For low aw, the increase in energy of activation (and enthalpy of activation) is accordingly counteracted by a more positive entropy of activation, in agreement with decarboxylation as rate determining at low aw.     

Non-target beetles (Coleoptera) in Trypodendron pheromone traps in Finland

Non-target beetles were surveyed in Trypodendron pheromone traps in 3 localities in Finland. Two window traps baited with Trypolure, containing lineatin dissolved in ethanol, and one control trap without attractant were used in each locality. A total of 1648 specimens belonging to 223 non-target species were recorded. The species were divided into five ecological groups to be treated separately. Hylurgops palliatus and Hylastes cunicularius were abundant in baited traps, whereas other scolytids as a group did not show clear attraction. Other species living in recently dead trees, including bark- and wood-boring species and associated species (predators, scavengers, fungivores, etc.), were clearly attracted by Trypolure. The most abundant ones were Hylecoetes flabellicornis, Thanasimus formicarius, Rhizophagus dispar, and Rhizophagus nitidulus. Although numerous in the samples, saproxylic species inhabiting more decayed wood and non-saproxylic species did not seem to be attracted. Grouping of species into ecological groups was helpful in the search for attraction patterns among species that usually are scarce in pheromone traps.     

Transglutaminase catalyzed cross-linking of sodium caseinate improves oxidative stability of flaxseed oil emulsion

Sodium caseinate was modified by transglutaminase catalyzed cross-linking reaction prior to the emulsification process in order to study the effect of cross-linking on the oxidative stability of protein stabilized emulsions. The extent of the cross-linking catalyzed by different dosages of transglutaminase was investigated by following the ammonia production during the reaction and using SDS-PAGE gel. O/W emulsions prepared with the cross-linked and non-cross-linked sodium caseinates were stored for 30 days under the same conditions. Peroxide value measurement, oxygen consumption measurement, and headspace gas chromatography analysis were used to study the oxidative stability of the emulsions. The emulsion made of the cross-linked sodium caseinate showed an improved oxidative stability with reduced formation of fatty acid hydroperoxides and volatiles and a longer period of low rate oxygen consumption. The improving effect of transglutaminase catalyzed cross-linking could be most likely attributed to the enhanced physical stability of the interfacial protein layer against competitive adsorption by oil oxidation products.