Salmonella in Broiler Litter and Properties of Soil at Farm Location

Contamination of litter in a broiler grow-out house with Salmonella prior to placement of a new flock has been shown to be a precursor of the flock''s Salmonella contamination further down the production continuum. In the southern USA, broiler grow-out houses are primarily built on dirt pad foundations that are placed directly on top of the native soil surface. Broiler litter is placed directly on the dirt pad. Multiple grow-out flocks are reared on a single litter batch, and the litter is kept in the houses during downtime between flocks. The effects of environmental determinants on conditions in broiler litter, hence Salmonella ecology within it, has received limited attention. In a field study that included broiler farms in the states of Alabama, Mississippi and Texas we assessed Salmonella in broiler litter at the end of downtime between flocks, i.e. at the time of placement of a new flock for rearing. Here we utilized these results and the U.S. General Soil Map (STATSGO) data to test if properties of soil at farm location impacted the probability of Salmonella detection in the litter. The significance of soil properties as risk factors was tested in multilevel regression models after accounting for possible confounding differences among the farms, the participating broiler complexes and companies, and the farms'' geographical positioning. Significant associations were observed between infiltration and drainage capabilities of soil at farm location and probability of Salmonella detection in the litter.     

Sheep Movement Networks and the Transmission of Infectious Diseases

Background and Methodology

Various approaches have been used to investigate how properties of farm contact networks impact on the transmission of infectious diseases. The potential for transmission of an infection through a contact network can be evaluated in terms of the basic reproduction number, R ₀. The magnitude of R ₀ is related to the mean contact rate of a host, in this case a farm, and is further influenced by heterogeneities in contact rates of individual hosts. The latter can be evaluated as the second order moments of the contact matrix (variances in contact rates, and co-variance between contacts to and from individual hosts). Here we calculate these quantities for the farms in a country-wide livestock network: >15,000 Scottish sheep farms in each of 4 years from July 2003 to June 2007. The analysis is relevant to endemic and chronic infections with prolonged periods of infectivity of affected animals, and uses different weightings of contacts to address disease scenarios of low, intermediate and high animal-level prevalence.

Principal Findings and Conclusions

Analysis of networks of Scottish farms via sheep movements from July 2003 to June 2007 suggests that heterogeneities in movement patterns (variances and covariances of rates of movement on and off the farms) make a substantial contribution to the potential for the transmission of infectious diseases, quantified as R ₀, within the farm population. A small percentage of farms (<20%) contribute the bulk of the transmission potential (>80%) and these farms could be efficiently targeted by interventions aimed at reducing spread of diseases via animal movement.     

Purinergic Membrane Receptors as Targets for the Effect of Purotoxin 1, a Component of Venom of Spiders from the <Emphasis Type="Italic">Geolycosa</Emphasis> Genus

We examined effects of purotoxin 1 (PT1), a component of the venom of Geolycosa spiders, on a few voltageand ligand-operated ion channels present in the plasma membrane of sensory neurons from the rat dorsal root ganglia (DRGs). Purotoxin 1 in a 100 nM concentration evoked no changes in ion currents through voltage-operated sodium, potassium, and calcium channels in the membranes of isolated sensory neurons. This agent was also found to be ineffective with respect to capsaicin-sensitive receptor-channel complexes (TRPV1). Testing of the effects of PT1 on purinergic receptor-channel complexes P2X3, P2X2, and P2X2/3 showed that this toxin is a highly selective blocker of exclusively P2X3 receptors. The selectivity of action of PT1 demonstrated in our experiments shows that it is a unique agent, which opens up new prospects in the studies of structural/functional peculiarities of receptor-channel complexes P2X3 as a peripheral link of the nociception system.     

Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats

Background

The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl₄) in rats.

Results

The animals were divided into four groups with six rats in each group. CCl₄ (0.125 mL kg^-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg^-1 body wt.) was given by gavage 7 days before the CCl₄ injection. Bixin prevented the liver damage caused by CCl₄, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl₄ by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment.

Conclusion

Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl₄ is related to the antioxidant activity of the compound.     

Last glacial maximum biomes reconstructed from pollen and plant macrofossil data from northern Eurasia

Pollen and plant macrofossil data from northern Eurasia were used to reconstruct the vegetation of the last glacial maximum (LGM: 18,000 ± 2000 ¹⁴C yr bp ) using an objective quantitative method for interpreting pollen data in terms of the biomes they represent ( Prentice et al., 1996 ). The results confirm previous qualitative vegetation reconstructions at the LGM but provide a more comprehensive analysis of the data. Tundra dominated a large area of northern Eurasia (north of 57°N) to the west, south and east of the Scandinavian ice sheet at the LGM. Steppe‐like vegetation was reconstructed in the latitudinal band from western Ukraine, where temperate deciduous forests grow today, to western Siberia, where taiga and cold deciduous forests grow today. The reconstruction shows that steppe graded into tundra in Siberia, which is not the case today. Taiga grew on the northern coast of the Sea of Azov, about 1500 km south of its present limit in European Russia. In contrast, taiga was reconstructed only slightly south of its southern limit today in south‐western Siberia. Broadleaved trees were confined to small refuges, e.g. on the eastern coast of the Black Sea, where cool mixed forest was reconstructed from the LGM data. Cool conifer forests in western Georgia were reconstructed as growing more than 1000 m lower than they grow today. The few scattered sites with LGM data from the Tien‐Shan Mountains and from northern Mongolia yielded biome reconstructions of steppe and taiga, which are the biomes growing there today.     

Recognition sites of monoclonal antibodies A4 and A24 in the α-latrotoxin molecule

α-Latrotoxin (α-LTX) binding sites to functionally active monoclonal antibodies (MA) A4 and A24 were localized using three approaches: hydrolysis of the toxin followed by theN-terminal sequencing of immunoreactive peptides; the study of antibody interaction with several recombinant α-LTX fragments; Western immunoblotting of synthetic overlapping peptides (6–8 aa) whose structures correspond to that of the immunoreactive α-LTX fragment. It was shown that the MA A4 epitope is located within the F²³⁴-M²⁹⁴ protein fragment and that MA A24 interacts with the fragment³⁴⁷FDKDIT³⁵².     

Action of surface-active substances on biological membranes IV. Hemolytic and membrane-perturbing action of homologous series of β-d-glucopyranosyl-1-alkylphosphates

The hemolytic action of a homologous series of β-d-glucopyranosyl-1-alkylphosphates on human erythrocytes has been examined. The agent's affinity for the red cell membrane and the mean number of the agent's molecules which, upon interaction with an erythrocyte, make it undergo hemolysis have been measured. The contribution of the head group and that of a CH₂ group of the surfactants to the free energy of the agents' binding to the cell membrane have been estimated. The effect of the surfactants on the red cell volume and the lytic concentrations of the agents have been measured. The contribution of a CH₂ group to the free energy of the interaction of the amphiphiles embedded in the membrane bilayer with their environment has been evaluated and is proposed to be used as a measure of the membrane matrix stability.     

Mating behavior in mutant strains of Drosophila melanogaster at different population densities

The effects of mutations and genetic background on the mating activity of males and receptivity of females Drosophila melanogaster have been studied at different population densities. Population density, as well as its combinations with other factors, significantly affects mating behavior of D. melanogaster. There are two distinct trends in the effect of this factor on mating behavior: the maximum larval overpopulation may cause either a significant suppression of the behaviors studied or an increase in their expressivity. The mating behaviors of w ^a and cn mutants against a certain genetic background changed similarly in response to varying population density.     

Antioxidant-caused changes in the permeability of proton-gated ion channels for sodium and calcium

Using a patch-clamp technique in the whole-cell configuration, we studied the effect of an exogenous antioxidant, dithiothreitol (DTT), on transmembrane currents in isolated cells obtained from the rat spinal ganglia. We demonstrated that this antioxidant (DTT) is capable of modulating the proton-gated current. In most neurons, proton-gated currents increased in the presence of the antioxidant. Since proton-gated receptor-channel complexes of sensory neurons are involved in different processes of signalling and transmission of sensory information in the peripheral nervous system, we hypothesize that the influences mediated by alterations of the concentrations of antioxidants participate in the formation of the state of algesia under normal physiological conditions and of that of hyperalgesia in pathological states. In addition, oxidative stress, which causes a shift in the balance of concentrations of antioxidants, accompanies numerous abnormal pathophysiological states, in particular diabetes, ischemia, and inflammation. Since proton-gated channels are permeable for calcium ions, an antioxidant-induced increase in calcium signalling can be significantly important for a number of biochemical processes occurring in tissues. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 193–197, May–June, 2006.