Transmission of Yersinia pseudotuberculosis in the Pork Production Chain from Farm to Slaughterhouse

The transmission of Yersinia pseudotuberculosis in the pork production chain was followed from farm to slaughterhouse by studying the same 364 pigs from different production systems at farm and slaughterhouse levels. In all, 1,785 samples were collected, and the isolated Y. pseudotuberculosis strains were analyzed by pulsed-field gel electrophoresis. The results of microbial sampling were combined with data from an on-farm observation and questionnaire study to elucidate the associations between farm factors and the prevalence of Y. pseudotuberculosis. Following the same pigs in the production chain from farm to slaughterhouse, we were able to show similar Y. pseudotuberculosis genotypes in live animals, pluck sets (containing tongue, tonsils, esophagus, trachea, heart, lungs, diaphragm, liver, and kidneys), and carcasses and to conclude that Y. pseudotuberculosis contamination originates from the farms, is transported to slaughterhouses with pigs, and transfers to pluck sets and carcasses in the slaughter process. The study also showed that the high prevalence of Y. pseudotuberculosis in live pigs predisposes carcasses and pluck sets to contamination. When production types and capacities were compared, the prevalence of Y. pseudotuberculosis was higher in organic production than in conventional production and on conventional farms with high rather than low production capacity. We were also able to associate specific farm factors with the prevalence of Y. pseudotuberculosis by using a questionnaire and on-farm observations. On farms, contact with pest animals and the outside environment and a rise in the number of pigs on the farm appear to increase the prevalence of Y. pseudotuberculosis.     

The effects of sex, age and breeding success on breeding dispersal of pied flycatchers along a pollution gradient

We modelled breeding dispersal of an insectivorous bird, the pied flycatcher (Ficedula hypoleuca) around a point source of heavy metals (a copper smelter). We tested for the effects of sex, age, breeding success and environmental pollution on breeding dispersal distances of F. hypoleuca females and males. Unlike many earlier studies on breeding dispersal, we took into account distance-dependent sampling bias by including in our model the recapture probabilities at different distances from the site of origin. Our results show that F. hypoleuca females disperse much farther (on average 7.9 km) from their breeding sites than what was previously thought. In contrast, males only disperse short distances (on average 190 m). Breeding success affected female breeding dispersal distances depending on female age: young females moved on average 8 km from their previous breeding place irrespective of their breeding success, while old females only seemed to move this far when their fledgling production was good. Females successful in their breeding dispersed as far as less successful females, or, among old birds, even farther. Females which dispersed long distances produced more fledglings after the movement than those staying near their previous breeding site. Degree of environmental pollution had no effect on female or male breeding dispersal distances. A polluted and unproductive environment does not seem to stimulate F. hypoleuca parents to move to more profitable territories.     

Climatic warming increases isoprene emission from a subarctic heath

Emissions of isoprene, a reactive hydrocarbon, from Subarctic vegetation are not well documented. However, the Arctic is likely to experience the most pronounced effects of climatic warming, which may increase temperature-dependent isoprene emission. Here, we assessed isoprene emission from a Subarctic heath subjected to a 3-4 degrees C increase in air temperature and mountain birch (Betula pubescens ssp. czerepanovii) litter addition for 7-8 yr, simulating climatic warming and the subsequent expansion of deciduous shrub species and migration of the treeline. The measurements were performed using the dynamic chamber method on a wet heath with a mixture of shrubs, herbs and graminoids. Isoprene emissions averaged across the treatments were 36 +/- 5 microg m(-2) h(-1) in 2006 and 58 +/- 7 microg m(-2) h(-1) in 2007. The experimental warming increased the emissions by 83% in 2007 (P = 0.021) and by 56% in 2006 (P = 0.056), while litter addition had no significant effects. The net ecosystem CO(2) exchange was significantly decreased by warming in 2007. These results show that isoprene emissions from Subarctic heaths are comparable to those from Subarctic peatlands. Climatic warming will increase the emissions, and the amount of carbon lost as isoprene, from Subarctic heath ecosystems.     

Variation of non-structural carbohydrates in silver birch (Betula pendula Roth) wood

Non-structural carbohydrates in silver birch (Betula pendula Roth) wood were analysed in a 7-year-old clone and in five mature stems. The analysis was conducted to obtain more detailed information on seasonal fluctuation of these components and of the tree-to-tree variation and within stem variation. The sugars were analysed by GLC-MS. The smallest total soluble sugar amounts (consisting of sucrose, fructose, glucose, raffinose and myo-inositol) in young trees were measured during mid-summer (ca. 0.3%) and the largest while in dormancy (ca. 1.6% on wood dry weight basis). Raffinose was detected in autumn as a minor component. The proportion of monosaccharides and the amount of myo-inositol were largest during growth. Compared to other studies silver birch showed more evident seasonal fluctuation in soluble sugars than evergreen tree species. The sugar amount in mature stems was approximately at the same level as in young trees that had the same felling time. Tree-to-tree variation in the non-structural carbohydrates in the mature wood was fairly large. However, the amount of total soluble sugars, sucrose and glucose showed significant variation within the stem. The amount of these sugars was largest in samples that were taken close to the cambium. Starch was also detected close to pith. According to the heartwood definition and starch measurement results in this paper, it could be stated that silver birch does not form heartwood.     

Structural basis for the proinflammatory cytokine activity of high mobility group box 1

High mobility group box 1 (HMGB), a ubiquitous DNA-binding protein, has been implicated as a proinflammatory cytokine and late mediator of lethal endotoxemia. HMGB1 is released by activated macrophages. It amplifies and extends the inflammatory response by inducing cytokine release and mediating acute lung injury, anorexia, and the inflammatory response to tissue necrosis. The kinetics of HMGB1 release provide a wide therapeutic window for endotoxemia because extracellular levels of HMGB1 begin to increase 12 to 24 h after exposure to inflammatory stimuli. Here, we demonstrate that a DNA-binding domain of HMGB1, the B box, recapitulates the cytokine activity of full length HMGB1 and efficiently activates macrophages to release tumor necrosis factor (TNF) and other proinflammatory cytokines. Truncation of the B box revealed that the TNF-stimulating activity localizes to 20 amino acids (HMGB1 amino acids 89 to 108). Passive immunization of mice with antibodies raised against B box conferred significant protection against lethal endotoxemia or sepsis, induced by cecal perforation. These results indicate that a proinflammatory domain of HMGB1 maps to the highly conserved DNA-binding B box, making this primary sequence a suitable target in the design of therapeutics.     

Regulation of the sequential processing of Semliki Forest virus replicase polyprotein

The replication of most positive-strand RNA viruses and retroviruses is regulated by proteolytic processing. Alphavirus replicase proteins are synthesized as a polyprotein, called P1234, which is cleaved into nsP1, nsP2, nsP3, and nsP4 by the carboxyl-terminal protease domain of nsP2. The cleavage intermediate P123+nsP4 synthesizes minus-strand copies of the viral RNA genome, whereas the completely processed complex is required for plus-strand synthesis. To understand the mechanisms responsible for this sequential proteolysis, we analyzed in vitro translated Semliki Forest virus polyproteins containing noncleavable processing sites or various deletions. Processing of each of the three sites in vitro required a different type of activity. Site 3/4 was cleaved in trans by nsP2, its carboxyl-terminal fragment Pro39, and by all polyprotein proteases. Site 1/2 was cleaved in cis with a half-life of about 20-30 min. Site 2/3 was cleaved rapidly in trans but only after release of nsP1 from the polyprotein exposing an "activator" sequence present in the amino terminus of nsP2. Deletion of amino-terminal amino acids of nsP2 or addition of extra amino acid residues to its amino terminus specifically inhibited the protease activity that processes the 2/3 site. This sequence of delayed processing of P1234 would explain the accumulation of P123 plus nsP4, the early short-lived minus-strand replicase. The polyprotein stage would allow correct assembly and membrane association of the RNA-polymerase complex. Late in infection free nsP2 would cleave at site 2/3 yielding P12 and P34, the products of which, nsP1-4, are distributed to the plasma membrane, nucleus, cytoplasmic aggregates, and proteasomes, respectively.     

Hydrogen peroxide activates cell death and defense gene expression in birch

The function of hydrogen peroxide (H(2)O(2)) as a signal molecule regulating gene expression and cell death induced by external stresses was studied in birch (Betula pendula). Ozone (O(3)), Pseudomonas syringae pv syringae (Pss), and wounding all induced cell death of various extents in birch leaves. This was temporally preceded and closely accompanied by H(2)O(2) accumulation at, and especially surrounding, the lesion sites. O(3) and Pss, along with an artificial H(2)O(2) producing system glucose (Glc)/Glc oxidase, elicited elevated mRNA levels corresponding to genes encoding reactive oxygen species detoxifying enzymes, Pal, Ypr10, and mitochondrial phosphate translocator 1. In addition to the regulation of gene expression, Glc/Glc oxidase also induced endogenous H(2)O(2) production in birch leaves, accompanied by cell death that resembled O(3) and Pss damage. Wound-induced gene expression differed from that induced by O(3) and Pss. Thus, it appears that at least two separate defense pathways can be activated in birch leaves by stress factors, even though the early H(2)O(2) accumulation response is common among them all.