Imidacloprid impairs memory and brain metabolism in the honeybee (Apis mellifera L.)

Imidacloprid is a chloronicotinyl insecticide which interacts with insect nicotinic acetylcholine receptors. Thirty minutes after oral treatment of honeybees with imidacloprid, the olfactory learning performances in a proboscis extension reflex (PER) procedure were impaired. In parallel, an increase of the cytochrome oxidase labelling was found into the calyces of the mushroom bodies. Imidacloprid administered 15 min or 1 h after a one-trial conditioning of PER impaired the medium-term olfactory memory. By contrast, the short-term (30 s or 3 min conditioning-treatment time interval) and long-term (24 h conditioning-treatment time interval) memories were unaffected. The impairment of medium-term olfactory memory by imidacloprid is discussed in the context of neural circuits suspected to mediate memory formation in the honeybee brain.     

Epidemiologic characteristics of catastrophic musculoskeletal injuries in Thoroughbred racehorses

OBJECTIVE: To determine characteristics, incidence rate, and possible associations with selected demographic characteristics of catastrophic musculoskeletal injuries (CMIs) in Thoroughbred racehorses. ANIMALS: 76 Thoroughbreds with CMIs. PROCEDURES: Incidence rates of CMIs during racing or training were calculated with number of CMIs as the numerator and overall numbers of races or training events during 2004 and 2005 as the denominators. Exact 95% confidence intervals were calculated. Associations between incidence and dichotomous exposure factors, nominal factors, and ordinal factors were determined. Only univariable associations were examined. RESULTS: 76 horses were euthanized because of CMI and represented 2.36 and 1.69 deaths/1,000 racing starts in 2004 and 2005, respectively. Of these, 57 were euthanized within 60 days before or after a race, which yielded a point incidence of 1.05/1,000 racing starts and 0.39/1,000 training starts. CONCLUSIONS AND CLINICAL RELEVANCE: Incidence rate of CMIs at 2 Ontario racetracks was similar to that at other North American racetracks. A cumulative death rate of 1 to 2 deaths/wk should be considered typical when designing prevention strategies and offers a baseline value for measuring improvement.     

Strain and excursion of the sciatic nerve in the dog: biomechanical considerations in the development of a clinical test for increased neural mechanosensitivity

Analysis of human nerve biomechanics has contributed to the validation of clinical tests to diagnose back pain of neural origin. Equivalent clinical tests for dogs would be valuable to differentially diagnose lumbosacral pain. To develop such a test, the increase in strain in the sciatic nerve of dogs and the longitudinal excursion of the nerve in relation to its surrounding structures during hind limb movements were evaluated. A miniature strain gauge was inserted into the sciatic nerve in seven canine cadavers and excursion was measured using a digital calliper. A cumulative increase in strain of 7.2% (+/-2.8%) was observed for the combined movements of hip flexion, stifle extension, hock flexion and digit extension (P<0.0001). Although all components contributed significantly to the increase (P=0.03), the sciatic nerve demonstrated a curvilinear response to increased loading. A 10.0+/-1.0mm excursion was recorded with stifle extension (P=0.002). It was concluded that, the sciatic nerve in dogs accommodates to joint movements by stretching and gliding. This biomechanical analysis has contributed to the development of a clinical test equivalent to the human straight leg raise to evaluate increased mechanosensitivity of the lumbosacral plexus.     

Pulsed-field gel electrophoresis and multi locus sequence typing for characterizing genotype variability of Yersinia ruckeri isolated from farmed fish in France

Yersinia ruckeri is a pathogen that has an impact on aquaculture worldwide. The disease caused by this bacterial species, yersiniosis or redmouth disease, generates substantial economic losses due to the associated mortality and veterinary costs. For predicting outbreaks and improving control strategies, it is important to characterize the population structure of the bacteria. The phenotypic and genetic homogeneities described previously indicate a clonal population structure as observed in other fish bacteria. In this study, the pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST) methods were used to describe a population of isolates from outbreaks on French fish farms. For the PFGE analysis, two enzymes (NotI and AscI) were used separately and together. Results from combining the enzymes showed the great homogeneity of the outbreak population with a similarity > 80.0% but a high variability within the cluster (cut-off value = 80.0%) with a total of 43 pulsotypes described and an index of diversity = 0.93. The dominant pulsotypes described with NotI (PtN4 and PtN7) have already been described in other European countries (Finland, Germany, Denmark, Spain and Italy). The MLST approach showed two dominant sequence types (ST31 and ST36), an epidemic structure of the French Y. ruckeri population and a preferentially clonal evolution for rainbow trout isolates. Our results point to multiple types of selection pressure on the Y. ruckeri population attributable to geographical origin, ecological niche specialization and movements of farmed fish.     

Habitat,geophysical, and eco-social connectivity: benefits of resilient socio–ecological landscapes

Landscape Ecology - Connections among ecosystems and their components are critical to maintaining ecological functions and benefits in human-modified landscapes, including urban areas. However, the...     

Virulence profiles of enterotoxigenic, shiga toxin and enteroaggregative Escherichia coli in South African pigs

Enterotoxigenic Escherichia coli (ETEC) and shiga toxin E. coli (STEC) are important causes of colibacillosis in piglets. Recently, enteroaggregative E. coli heat-stable enterotoxin 1 (EAST-1) has been implicated in pig diarrhoea. This study investigated the prevalence of enterotoxin [heat-labile toxins (LT), heat-stable toxin a (STa), heat-stable toxin b (STb)], shiga toxins (Stx1, Stx2, Stx2e), enteroaggregative heat-stable E. coli (EAST-1), associated fimbriae (F4, F5, F6, F41, F18ab, F18ac) and non-fimbrial adhesins [adhesin involved in diffuse adherence 1 (AIDA-1), attaching and effacing factor, porcine attaching- and effacing-associated factor] in South African pigs. A total of 263 E. coli strains were isolated from Landrace (n?=?24), Large White (n?=?126), Duroc (n?=?28) and indigenous (n?=?85) breeds of piglets aged between 9 and 136 days. PCR was used in the analysis. Virulent genes were detected in 40.3 % of the isolates, of which 18.6, 0.4 and 17.5 % were classified as ETEC, STEC and enteroaggregative E. coli (EAEC), respectively. Individual genes were found in the following proportions: STb (19.01 %), LT (0.4 %), STa (3.4 %), St2xe (1.1 %) and EAST-1 (20.2 %) toxins. None of the tested fimbriae were detected in ETEC and STEC isolates. About one third of the ETEC and STEC isolates was tested negative for both fimbrial and non-fimbrial adhesins. Twenty-five pathotypes from ETEC-, EAEC- and STEC-positive strains were identified. Pathotypes EAST-1 (30.2 %), STb (13.2 %) and STb/AIDA-1 (10.4 %) were most prevalent. The study provided insight on possible causes of colibacillosis in South African pigs.     

赛乐硒对发情奶牛外周血生殖激素含量和繁殖性能的影响

选用35头处于干奶期40d、泌乳期相近和上胎平均日产奶量20kg的荷斯坦奶牛,采用完全随机区组设计分为7组,即:对照组,基础日粮(不加硒);试验组1、2、3添加亚硒酸钠,分别在基础日粮中加硒7.5mg/d、15mg/d和22.5mg/d;试验组4、5、6添加赛乐硒,分别在基础日粮中加硒7.5mg/d、15mg/d和22.5mg/d,研究赛乐硒和无机硒对奶牛发情周期生殖激素分泌和繁殖性能的影响。结果表明:赛乐硒较无机硒显著提高了发情周期促性腺激素释放激素、促卵泡素、促黄体素、雌二醇和孕酮含量,显著提高了受配率和受胎率,缩短了胎衣排出周期,促进母牛正常发情。适宜补硒量为15 mg/d。