Insensitive acetylcholinesterase,high glutathione-S-transferase,and hydrolytic activity as resistance factors in a tetrachlorvinphos-resistant strain of house fly

The gene producing insensitive acetylcholinesterase in a tetrachlorvinphos-resistant strain of house fly was introduced into the genome of a susceptible strain. The resistance to a number of organophosphorus insecticides, which was high in the original strain (234- and more than 800-fold for paraoxon and tetrachlorvinphos, respectively), was much lower in the resulting strain, ranging from 53-fold for paraoxon to 3.9-fold for tetrachlorvinphos. Synergists further decreased these factors. The reduction in sensitivity of the acetylcholinesterase in vitro was about 20-fold for both inhibitors. The Michaelis parameters for hydrolysis of acetylcholine and acetylthiocholine of the mutant and normal acetylcholinesterase showed only minor differences. An increased rate of metabolism of the insecticides was found in the original strain. In vitro, glutathione-dependent detoxication was from 9- to 120-fold that of a susceptible strain, depending on the insecticide and the conditions used. The enzyme de-alkylated parathion and methylparaoxon, but there was no de-arylation of parathion, although it is important in other strains. In vitro, paraoxon and methylparaoxon were also hydrolysed, and this is not so in the susceptible strain. The high resistance present in the original strain seems to be due to joint action of at least three mechanisms.     

Distribution and dynamics of the red squirrel (Sciurus vulgaris L.) in a landscape with fragmented habitat

In a four year study data on the presence of red squirrel were collected in an agricultural landscape by counting dreys in 49 woods ranging from 0.5 to 14 ha, and differing in quality of habitat and isolation.Logit regression analysis showed that the area per woodlot covered with conifers is a good predictor of squirrel presence for each year and during the whole period, but the significance of the regression decreases with time. During the study the number of woods occupied by red squirrel increased, and smaller woods and those without conifers also became inhabited. This trend is in accordance with the positive effect of time in regression analyses on the presence of the species and on the colonization of woods, and it suggests an increase of squirrel numbers in the area. Addition of several isolation variables in the regression analyses showed significant effects in different years, and the effect of isolation was independent of time. In the first two years the area of habitat around a woodlot, the distance to the nearest woodlot larger than 30 ha, and the density of possible movement corridors have significant effects on the presence of red squirrel.In the last two years, with presumably a high number of squirrels, the (short) distance to the nearest woodlot and also the area of habitat around woods have significant effects. It is concluded that the spatial dynamics of the population can be understood as the outcome of individual spatial behaviour, rather than as the result of metapopulation processes.     

Structure assignment to biologically produced malathion monocarboxylic acid isomers with 13C-nuclear magnetic resonance

Chemical synthesis of malathion α- and β-monocarboxylic acid yields a mixture of the two structural isomers. These two isomers were separated by preparative anion-exchange chromatography on QAE-Sephadex. ¹³C-Nuclear magnetic resonance of the pure components shows that the main product is the β-isomer, with the α-isomer being present in much smaller quantities. This result was used for identification of hydrolytic malathion metabolites produced by rat tissues. On incubation of malathion with rat liver fractions in vitro it was found that α- and β-monoacid are formed in a ratio of 3:2, whereas this ratio is 9:2 for the metabolites excreted into the urine after intraperitoneal injection of malathion in rats.     

Arcobacter, what is known and unknown about a potential foodborne zoonotic agent!

Since the introduction of the genus Arcobacter in 1991, the association of Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii with humans and animals has been clearly established. These bacteria have been detected world wide in products of animal origin and in healthy animals as well as in surface water. A fourth species Arcobacter cibarius was recently discovered on chicken carcasses. Although evidence was found for the connection of Arcobacter spp. with human and animal illness, Arcobacter spp. can be pathogens, opportunistic pathogens and commensals. Their potential as zoonotic foodborne and waterborne agents, the routes of transmission and the pathogenic mechanisms of these bacteria are largely unknown. Production of toxins or other virulence factors has not been demonstrated but adhesive and/or invasive properties were apparent. Antibiotic resistance is present in Arcobacter strains to significant levels. The tools to genetically access Arcobacter-like transformation of strains, construction of mutants are not yet available. Nor have genes (i.e. potential virulence factors) been cloned, expressed and characterized in other host organisms. Therefore those interested in the microbiology of these organisms eagerly await publication of the complete nucleotide sequence of the Arcobacter genome. The abundant presence of four Arcobacter species in foods of animal origin and the recovery of these bacteria from surface and drinking water suggest an important role of these bacteria as foodborne or waterborne agent and possibly as zoonotic agent.     

The role of ferrous ions in the rapid degradation of oxamyl,methomyl and aldicarb in anaerobic soils

The carbamoyloxime pesticides methomyl, oxamyl and aldicarb, together with the oxidation products of aldicarb, are known to break down much more rapidly in certain anaerobic subsoils than in the aerobic topsoils from the same site. Ferrous ions have now been shown to be involved in this reaction. Oxamyl was degraded in aqueous solutions at 30°C containing 250 μg ml^?1 Fe²⁺ with a half-life of about 10 h, independent of pH in the range of 5.65–7.66; the observed products of this reaction were N,N-dimethyl-l-cyanoformamide and methanethiol. These same products, rather than the oximino hydrolysis product observed from degradation in aerobic soils, were rapidly and quantitatively formed from oxamyl in suspensions of anaerobic reduced subsoils (Fe²⁺ concentration 27–41 μg ml^?1 soil water), but oxamyl was rather stable in water-saturated Vredepeel subsoil (Fe²⁺ concentration 0.65 μg ml^?1) in which the redox potential was much higher. Methomyl behaved similarly. The rates of reaction in the suspensions of anaerobic subsoils were greater than expected from the concentrations of Fe²⁺ in the soil water, but most of the Fe²⁺ present in soil was bound to the soil particles by cation exchange and this bound Fe²⁺ may have participated. Breakdown of aldicarb was accelerated both in solutions of Fe²⁺ and in the suspensions of anaerobic reduced subsoils, though the rate enhancement was less than observed with methomyl and oxamyl; 2-methyl-2-methylthiopropionitrile and 2-methyl-2-methylthiopropionaldehyde were the observed products from aldicarb in anaerobic soil but only the former was produced in Fe²⁺ solutions; the corresponding nitriles and aldehydes were also yielded by aldicarb sulphoxide and aldicarb sulphone in the anaerobic, reduced subsoils.     

Effects of vegetation pattern and of biochar and powdery soil amendments on soil loss by wind in a semi-arid region

Dust emission from wind erosion is a widespread phenomenon in arid and semi-arid areas having considerable implications for ecosystems and human well-being. However, few studies have examined the efficiency of biochar amended to soil on wind erosion control. Aimed at studying the effect of biochar on resistance of soils against wind erosion, a wind tunnel experiment was conducted. We tested (a) soils amended with hard waste walnut wood biochar and soft maize cob biochar, and (b) soils amended with powdery waste wood and powdery maize cob, and compared them with (c) non-treated soil, in their susceptibility to wind erosion and also the additional effect of various patterns of vegetation cover. Amending soil with biochar and powdery material did significantly increase their resilience to wind erosion because of increased soil aggregation. In comparison with the non-treated control, the mass flux of un-vegetated soil reduced from 4.42 to 1.86 g m⁻² s⁻¹ for the waste walnut wood biochar, from 4.28 to 1.50 g m⁻² s⁻¹ for maize cob biochar, from 4.11 to 1.44 g m⁻² s⁻¹ for powdery maize cob and from 3.97 to 1.14 g m⁻² s⁻¹ for powdery waste walnut wood. When combining amendments with vegetation, there was still a substantial improvement, though the soil treatments responded differently in terms of soil loss to different vegetation patterns. A single row vegetation pattern had the highest mass flux, while a zigzag vegetation pattern had the lowest. In conclusion, waste wood or maize cobs, whether applied as biochar or as powdery material, are able to fix soil and reduce wind erosion.     

Rhodococcus equi

Rhodococcus equi is an important cause of subacute or chronic abscessating bronchopneumonia of foals up to 3-5 months of age. It shares the lipid-rich cell wall envelope characteristic of the mycolata, including Mycobacterium tuberculosis, as well as the ability of pathogenic members of this group to survive within macrophages. The possession of a large virulence plasmid in isolates recovered from pneumonic foals is crucial for virulence. The plasmid contains an 27 kb pathogenicity island (PI) that encodes seven related virulence-associated proteins (Vaps), including the immunodominant surface-expressed protein, VapA. Only PI genes are differentially expressed when the organism is grown in macrophages in vitro. Ten of the PI genes, including six Vap genes, have signal sequences, suggesting that they are exported from the cell to interact with the macrophage. Different PI genes are regulated by temperature, pH, iron, oxidative stress and probably also by magnesium, all environmental changes encountered after environmental R. equi are inhaled in dust and are ingested into macrophages in the lung. The basis of pathogenicity of R. equi is its ability to multiply in and eventually to destroy alveolar macrophages. Infectivity is largely or exclusively limited to cells of the monocyte-macrophage lineage. Current evidence suggests that infection of foals with virulent R. equi results in some foals in subversion of cell-mediated immunity and development of an ineffective and sometimes lethal Th2-based immune response. Significant progress has been made recently in the development of R. equi-E. coli shuttle vectors, transformation and random and site specific mutagenesis procedures, all of which will be important in molecular dissection of the mechanisms by which R. equi subverts normal macrophage killing mechanisms and cell-mediated immunity.     

Differential responses of silver birch (Betula pendula) ecotypes to short-day photoperiod and low temperature

We investigated interrelations of dormancy and freezing tolerance and the role of endogenous abscisic acid (ABA) in the development of silver birch (Betula pendula Roth) ecotypes in controlled environments. Short-day treatment induced growth cessation, bud set and dormancy development, as well as initiation of cold acclimation and an increase in freezing tolerance. Subsequent low temperature and short days (12-h photoperiod) resulted in a significant increase in freezing tolerance, whereas bud dormancy was gradually released. The concentration of ABA increased in response to short days and then remained high, but ABA concentrations fluctuated irregularly when the dormant plants were subsequently exposed to low temperature during short days. Although there was a parallel development of freezing tolerance and bud dormancy in response to short days, subsequent exposure to low temperature had opposite effects on these processes, enhancing freezing tolerance and releasing dormancy. Compared with the southern ecotype, the northern ecotype was more responsive to short days and low temperature, exhibiting earlier initiation of cold acclimation, growth cessation and an increase in ABA concentrations in short days, and higher freezing tolerance, faster dormancy release and greater alteration in ABA concentrations when subsequently exposed to low temperature during short days. The rates and extent of the increases in ABA concentration may be related to increases in freezing tolerance and dormancy development during short days, whereas the extent of the fluctuations in ABA concentration may play an important role in enhancing freezing tolerance and releasing dormancy during a subsequent exposure to low temperature during short days.     

Morphological and immunological characteristics of the bovine temporal lymph node and hemal node

Anatomical dissection of the temporal regions of 62 cattle demonstrated that lymph nodes and hemal nodes are present in 89% of the animals (bilaterally in 65% and unilaterally in 24% of the cases). Lymph nodes accounted for 60% and hemal nodes for 40% of all examined nodes. They are nearly always round with diameters ranging from 1 to 9mm. Injections of India ink showed that their drainage area consists of the forehead, the upper eyelid, the base of the horn and the temporal muscle. Immunohistochemistry and flow cytometry revealed that the distribution and percentages of the different cell populations in the lymph nodes and hemal nodes are similar to other cranial lymph nodes. Based on its anatomical location the name temporal lymph node (lymphonodus temporalis) is proposed.     

Do citizens and farmers interpret the concept of farm animal welfare differently?

Animal welfare is of increasing importance in livestock production and consumption debates. However, discordance exists between citizens' and farmers' perception of animal welfare. Since the search for, and the realization of improvements towards farm animal welfare is strongly driven by citizen expectations, it is of utmost importance to better understand this perceptual discordance. A quantitative study was done in Flanders, Belgium during 2006, including citizens as well as farmers, to obtain a detailed insight in the way the multi-dimensional concept of farm animal welfare is valued. This allowed to discriminate between issues of agreement and disagreement. In general, a similar interpretation of farm animal welfare in terms of animal welfare related aspect's ranking was found. Differences were mainly related to aspects dealing with the ability to engage in natural behaviour on the one hand and with production process-related aspects on the other hand. Citizens evaluate the current state of animal welfare as rather problematic, while farmers report a more satisfactory evaluation of the present condition of farm animal welfare. Especially differing opinions regarding the ability to engage in natural behaviour, together with aspects related to pain, stress and the availability of space seem to contribute to the discordance between farmers and citizens in terms of evaluative beliefs.