Effects of conventionally bred and <Emphasis Type="BoldItalic">Bacillus thuringiensis</Emphasis> (<Emphasis Type="BoldItalic">Bt</Emphasis>) maize varieties on soil microbial biomass and activity

Genetically modified (GM) maize containing genes from the soil bacterium Bacillus thuringiensis (Bt) was cultivated on 29% of the total maize production area worldwide in 2009. Most studies to date compare Bt-maize varieties with their near isogenic lines; however, there is little information on the variability of conventional maize breeding lines and how the effects of Bt varieties are ranked within. In our study on the potential risks of Bt-maize varieties, we analyzed tissue quality and compared the effects of ten conventional and GM maize varieties on soil microbiological properties in a replicated climate chamber experiment. All maize varieties were cultivated twice in the same soil microcosm. Shoot yields and soluble C in leaf tissue of Bt varieties were higher than the ones of non-Bt. Soil dehydrogenase activity was reduced by 5% under Bt varieties compared to non-Bt, while most of the other soil microbial properties (soil microbial biomass, basal respiration) showed no significant differences between Bt and non-Bt varieties. The leaves and roots of one Bt variety were decomposed to a greater extent than the ones of its near isogenic line; the conventional breeding lines also showed higher values. Changes in crop and soil parameters were found when comparing the first and the second crops, but the effects of repeated cropping were the same for all tested varieties. For the studied parameters, the variation among non-Bt-maize varieties was similar to the difference between Bt and non-Bt varieties.     

Basin‐scale distribution and haplotype partitioning in different genetic lineages of the Neotropical migratory fish Salminus brasiliensis

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Assessment of the hemodynamic effects of lidocaine administered IV in isoflurane-anesthetized cats

OBJECTIVE:To determine the hemodynamic effects of lidocaine (administered IV to achieve 6 plasma concentrations) in isoflurane-anesthetized cats. ANIMALS: 6 cats. PROCEDURE: Cats were anesthetized with isoflurane in oxygen (end-tidal isoflurane concentration set at 1.25 times the predetermined individual minimum alveolar concentration). Lidocaine was administered IV to each cat to achieve target pseudo-steady-state plasma concentrations of 0, 3, 5, 7 9, and 11 microg/mL, and isoflurane concentration was reduced to an equipotent concentration. At each plasma lidocaine concentration, cardiovascular and blood gas variables; PCV; and plasma total protein, lactate, lidocaine, and monoethylglycinexylidide concentrations were measured in cats before and during noxious stimulation. Derived variables were calculated. RESULTS: n isoflurane-anesthetized cats, heart rate, cardiac index, stroke index, right ventricular stroke work index, plasma total protein concentration, mixed-venous PO2 and hemoglobin oxygen saturation, arterial and mixed-venous bicarbonate concentrations, and oxygen delivery were significantly lower during lidocaine administration, compared with values determined without lidocaine administration. Mean arterial pressure, central venous pressure, pulmonary artery pressure, systemic and pulmonary vascular resistance indices, PCV, arterial and mixed-venous hemoglobin concentrations, plasma lactate concentration, arterial oxygen concentration, and oxygen extraction ratio were significantly higher during administration of lidocaine, compared with values determined without lidocaine administration. Noxious stimulation did not significantly affect most variables. CONCLUSIONS AND CLINICAL RELEVANCE: In isoflurane-anesthetized cats, although IV administration of lidocaine significantly decreased inhalant requirements, it appeared to be associated with greater cardiovascular depression than an equipotent dose of isoflurane alone. Administration of lidocaine to reduce isoflurane requirements is not recommended in cats.     

Trait–environment relationships in Amazon stream fish assemblages

Studies of trait–environment relationships provide important tools for the prediction of the response of biological communities to environmental alterations. The Amazon basin presents enormous potential for the development of research on this type of relationship, given the diversity of both its fish fauna and the aquatic ecosystems this fauna inhabits. The present study investigated the association between local environmental variables and the functional traits of fish in 54 streams of six major Amazonian basins. We identified the relationship between the characteristics of the streams (channel morphology, channel habitat units, riparian vegetation cover, large woody fragments and instream cover for aquatic organisms) and fish traits related to locomotion, habitat use and feeding behaviour. The fish fauna of the broader, deeper and more slowly flowing streams was dominated by nektobenthic species that exploit autochthonous resources such as fish and invertebrates. In narrow, fast‐flowing streams, by contrast, there was a predominance of benthic fishes with varying feeding habits, including periphytivorous and invertivorous species. Narrow, shady streams were inhabited by nektonic species adapted for the exploitation of resources from the marginal vegetation. The results of this study contribute to the understanding of the association between the functional structure of fish assemblages and local environmental variables in Amazonian streams. We hope that these findings will stimulate further research into the natural variation in stream fish assemblages that will ensure the development of more effective management strategies that better protect these important aquatic ecosystems.     

Predictive qualitative risk model of bovine rabies occurrence in Brazil

Bovine rabies remains endemic in Brazil and despite control efforts, the disease still spreads insidiously. The main vector is the hematophagous bat, Desmodus rotundus. The present work aimed to create a predictive qualitative model of the occurrence of bovine rabies in each municipality in 25 of the 27 Brazilian States. The risk of rabies transmission from bats to bovine was estimated using decision-tree models of receptivity and vulnerability. Questionnaires, which covered a number of questions related to the surveillance of possible risk factors, such as bovine rabies outbreaks in the previous year, the presence of bat roosts, bat rabies positivity and environmental changes, were sent to the local veterinary units of each State. The bovine density and geomorphologic features were obtained from national databases and geographic information systems. Of the 433 municipalities presenting bovine rabies outbreaks in 2010, 178 (41.1%) were classified by the model as high risk, 212 (49.0%) were classified as moderate risk, 25 (5.8%) were classified as low risk, whereas the risk was undetermined in 18 municipalities (4.1%). An ROC curve was built to determine if the risk evaluated by the model could adequately discriminate between municipalities with and without rabies occurrence in future years. The risk estimator for the year 2011 was classified as moderately accurate. In the future, these models could allow the targeting of rabies control efforts, with the adoption of control measures directed to the higher risk locations and the optimization of the field veterinary staff deployment throughout the country. Additionally, efforts must be made to encourage continuous surveillance of risk factors.     

Seroprevalence of Toxoplasma gondii in American free-ranging or captive pumas (Felis concolor) and bobcats (Lynx rufus)

Toxoplasma gondii is a major zoonotic agent infecting a wide range of mammals, including wild felids. Like domestic cats, wild felids are involved in the complete infective cycle of T. gondii, as they can host in their gastrointestinal tract sexually mature parasites and shed infective oocysts in their feces. In order to evaluate the importance of this wildlife reservoir, 438 serum samples collected between 1984 and 1999 from 438 pumas (Felis concolor) and from 58 bobcats (Lynx rufus) from North America, Central America and South America were screened for antibodies to T. gondii. The overall prevalence of T. gondii antibodies was 22.4% in pumas and 51.7% in bobcats, with regional variations. Adults were more likely to be seropositive than juveniles and kittens (prevalence ratio (PR) = 2.61; confidence interval (CI) = 1.15, 4.04). In the US, pumas from the southwestern states (Arizona, California and New Mexico) were more likely to be seropositive for T. gondii ( PR = 2.61; 95% CI = 1.32-5.18 ) than pumas from the northwestern and mountain states (Colorado, Idaho, Oregon, Utah and Wyoming). Male pumas from the US were more likely to be seropositive than females (PR = 2.08; 95% CI = 1.11-3.92), whereas female pumas from Mexico, Central America and South America were more likely to be seropositive than female pumas from Canada and the US (PR = 2.49; 95% CI = 1.09-5.69). Captive pumas were also more likely to be seropositive (21.7%, 29/92) for T. gondii than free-ranging animals (19.9%, 69/346) (PR = 1.85; 95% CI = 1.06, 3.17).     

Temporal shifts in landscape connectivity for an ecosystem engineer,the roe deer,across a multiple-use landscape

Context

Routine movements of large herbivores, often considered as ecosystem engineers, impact key ecological processes. Functional landscape connectivity for such species influences the spatial distribution of associated ecological services and disservices.

Objectives

We studied how spatio-temporal variation in the risk-resource trade-off, generated by fluctuations in human activities and environmental conditions, influences the routine movements of roe deer across a heterogeneous landscape, generating shifts in functional connectivity at daily and seasonal time scales.

Methods

We used GPS locations of 172 adult roe deer and step selection functions to infer landscape connectivity. In particular, we assessed the influence of six habitat features on fine scale movements across four biological seasons and three daily periods, based on variations in the risk-resource trade-off.

Results

The influence of habitat features on roe deer movements was strongly dependent on proximity to refuge habitat, i.e. woodlands. Roe deer confined their movements to safe habitats during daytime and during the hunting season, when human activity is high. However, they exploited exposed open habitats more freely during night-time. Consequently, we observed marked temporal shifts in landscape connectivity, which was highest at night in summer and lowest during daytime in autumn. In particular, the onset of the autumn hunting season induced an abrupt decrease in landscape connectivity.

Conclusions

Human disturbance had a strong impact on roe deer movements, generating pronounced spatio-temporal variation in landscape connectivity. However, high connectivity at night across all seasons implies that Europe’s most abundant and widespread large herbivore potentially plays a key role in transporting ticks, seeds and nutrients among habitats.

     

How to substantiate eradication of bovine brucellosis when aspecific serological reactions occur in the course of brucellosis testing

Collaborative work was financed by the EU to develop and assess new diagnostic tools that can differentiate between bovine brucellosis and bovine infections due to Yersinia enterocolitica O:9 either in conjunction with, or as an alternative to, the classical serological, bacteriological or allergic skin tests. Sixteen heifers were experimentally infected with Brucella abortus biovar 1 (five heifers), Brucella suis biovar 2 (two heifers), Y. enterocolitica O:9 (six heifers) and Y. enterocolitica O:3 (three heifers). Four heifers, naturally infected with Y. enterocolitica O:9 that presented aspecific brucellosis serological reactions were also included in the experiment. A self-limited infection was induced in cattle by B. suis biovar 2. All the brucellosis serological tests used, i.e. the slow agglutination test (SAW), the Rose Bengal test (RB), the complement fixation test (CFT), indirect and competitive ELISA’s, lacked specificity when used to analyze sera from Y. enterocolitica O:9 infected animals. A Yersinia outer membrane proteins (YOPs)-ELISA was also used and although the test is able to detect a Yersinia group infection, it provided no evidence of whether or not there is a possible brucellosis infection when dual infections are present. The brucellergen IFN-γ test showed a lack of specificity also. The only test that was proven to be specific is the brucellergen skin test. All brucellosis serological tests, except the indirect ELISA, were limited in their ability to detect B. abortus persistently infected animals.

Based on these experimental studies, a strategy was implemented as part of the year 2001 Belgian Brucellosis Eradication Program to substantiate the eradication of bovine brucellosis. Epidemiological inquiries have identified risk factors associated with aspecific serological reactions, possible transmission and infection of cattle by B. suis biovar 2 from infected wild boars; and both legal and administrative measures taken by the veterinary services. No cases of bovine brucellosis have been confirmed in Belgium since March 2000.     

Assessing the impact of <Emphasis Type="Italic">Dryocosmus kuriphilus</Emphasis> on the chestnut tree: branch architecture matters

Dryocosmus kuriphilus has become a major issue for chestnut (Castanea sativa) cultivation since its introduction in Europe. Thus far, however, quantitative assessments of the impact of D. kuriphilus in terms of green biomass loss are lacking. In the present study, we used the leaf area to sapwood area relationship (A _L:A _S)—based on the pipe model approach as a green biomass indicator—to quantitatively estimate the damage to chestnut trees caused by D. kuriphilus attacks and its recovery when the pest is controlled by Torymus sinensis in the chestnut stands of southern Switzerland. Leaf area loss is used as a response variable to select the most suitable explanatory architectural features at branch level to be combined in a damage index that permits a realistic assessment covering the entire epidemic. In our case study, the peak of the epidemic was reached in the fourth year of repeated D. kuriphilus attacks (leaf area losses exceeding 70%) with significant alterations in branch architecture. Although damage symptoms first decreased once biological control was reached (fifth year), branch architecture recovery was still lacking. From a methodological point of view, our A _L:A _S approach highlights how traditional methods of assessing the degree of infestation (i.e. proportion of attacked buds) fail to give sound estimations of resulting damage, whereas the proposed composite damage index enables a more realistic assessment of the entire epidemic process, including the recovery phase when the gall wasp is biologically controlled.