Effect of marbofloxacin on Haemophilus parasuis nasal carriage

Haemophilus parasuis is a colonizer of the upper respiratory tract and the causative agent of Gl?sser's disease in swine. This study focused on the nasal carriage of H. parasuis after treatment with marbofloxacin. Three marbofloxacin treatments (three doses of 2mg/kg body weight [bw] every 24h, two doses of 4 mg/kg bw every 48 h and 8 mg/kg bw in one single shot) were used and all of them reduce significantly (p<0.05) the nasal carriage of H. parasuis as compared to control animals. Moreover, H. parasuis was not detected in the nasal cavities of piglets after administering the highest dose. The effect of a dose of 8 mg marbofloxacin/kg bw in one shot was further studied in a farm with clinical cases of Gl?sser's disease using a longitudinal study. Statistically significant reduction of nasal carriage of H. parasuis was detected during the first week after treatment in comparison with the control group. However, a clear relationship between the minimum inhibitory concentration (MIC) of the different strains, their putative virulence or the treatment group (antibiotic or control) from which they were isolated was not detected. Finally, the effect induced by the antibiotic treatment on the bacterial strains seemed to be transitory, since diverse H. parasuis strains (with high and low marbofloxacin MICs) were observed 7 days after finishing the treatment.     

Antimicrobial resistance determinants among anaerobic bacteria isolated from footrot

Antibiotic resistance has been evaluated among 36 Gram negative and anaerobic bacilli (10 Bacteroides, 11 Prevotella, 7 Porphyromonas and 8 Fusobacterium strains) isolated from clinical cases of caprine and ovine footrot (necrotic pododermatitis). The initial analysis on this bacterial consortium evaluates the relationships existing among antimicrobial resistance determinants, phenotype expression and mobilization potential. The Bacteroides strains were generally resistant to penicillins, first-generation cephalosporins, tetracycline and erythromycin, and expressed low level of β-lactamase activity. The main determinants found among the Bacteroides strains were cepA and tetQ genes, conferring resistance to β-lactams and tetracycline, respectively. A general susceptibility to β-lactams was shown for most Prevotella, Porphyromonas and Fusobacterium strains, where none of the β-lactamase genes described in Bacteroides was detected. Resistance to tetracycline and/or erythromycin was found among the three bacterial groups. Although tetQ genes were detected for several Prevotella and Porphyromonas strains, a unique ermF positive was revealed among Prevotella strains. The expression of resistance markers was not related with the polymorphism of their coding sequences. However, the finding of sequence signatures for conjugative transposons in the vicinities of tetQ and ermF suggests a mobilization potential that might have contributed to the spread of antimicrobial resistance genes.     

Cadmium and Copper Effects on Larval Development and Mortality of the Polychaete Capitella Sp Y from Estero Del Yugo, Mazatlan, Mexico

The effects of cadmium and copper on larval metamorphosis and mortality of cultured Capitella sp Y were investigated. Metatrochophore larvae were exposed to 0.013 (control), 0.030, 0.080, 0.120, and 0.170 mg Cd L^?1 and 0.017 (control), 0.025, 0.060, and 0.075 mg Cu L^?1 for 34 days. Larval mortality significantly (p < 0.01) increased with increasing Cd and Cu concentrations (Kruskal-Wallis test), with similar effects for both metals for day 10 (LC₅₀ = 0.035 mg Cd L^?1 and 0.035 mg Cu L^?1). Metamorphosis was inhibited in larvae exposed to the two metals in the absence of food, the effect of Cu being the most severe. This study suggests that Cd and Cu exposure could be harmful to early developmental stages of Capitella sp Y producing a delay in recruitment into natural populations.     

DNA from pre-Clovis human coprolites in Oregon, North America

The timing of the first human migration into the Americas and its relation to the appearance of the Clovis technological complex in North America at about 11,000 to 10,800 radiocarbon years before the present (14C years B.P.) remains contentious. We establish that humans were present at Paisley 5 Mile Point Caves, in south-central Oregon, by 12,300 14C years B.P., through the recovery of human mitochondrial DNA (mtDNA) from coprolites, directly dated by accelerator mass spectrometry. The mtDNA corresponds to Native American founding haplogroups A2 and B2. The dates of the coprolites are >1000 14C years earlier than currently accepted dates for the Clovis complex.     

Aluminium Tolerance of Maize Cultivars as Assessed by Callose Production and Root Elongation

The differences in Al tolerance between 12 maize cultivars were investigated using early stress indicators such as relative root elongation rate, induction of callose formation and Al concentrations in 5 mm root tips. Plants were grown in nutrient solution (pH 4.3) and exposed to 0 (control), 20 or 50 μM Al for 24 h. According to the relative root elongation rates, Regent, C 525 M and Adour 250 were the most Al-tolerant cultivars, while BR 201 F, Teosinte, Alarik, Burras and HS 7777 were Al-sensitive. Cultivars Brummi, HS 1230, Lixis and Aladin showed an intermediate behaviour. A significant inverse correlation between relative root-elongation rates and both Al concentration in root tips and callose concentrations could be established. The usefulness of callose as an early indicator of Al stress and the importance of Al exclusion from root tips as an Al tolerance mechanism are discussed.     

SNP diversity in introduced populations of the invasive Gambusia holbrooki

Abstract – We used a targeted gene approach to amplify genomic fragments to characterise single‐nucleotide polymorphisms (SNPs) in introduced European populations of the invasive mosquitofish Gambusia holbrooki. Patterns of diversity within and among European populations of G. holbrooki and American collections of G. holbrooki and Gambusia affinis reveal unexpected high diversities within European populations. This ascertainment bias is one of the major challenges in the development of SNP markers for monitoring species involved in worldwide introductions. Pattern of diversity among European populations confirmed diverse introductions, as suggested by earlier mtDNA studies. However, SNPs showed larger differentiation between populations than had been previously detected with mtDNA sequencing. Five major population groups were identified: central France, southern Iberian, northern Iberian, Eastern Europe and Mediterranean French Rivers.     

IBQS: A synthetic index of soil quality based on soil macro-invertebrate communities

We developed a synthetic index of biological soil quality (IBQS) based on soil macro-invertebrate community patterns to assess soil quality. In 22 sites representing the diversity of agroecosystems encountered in France, invertebrate communities co-varied significantly with a set of 14 parameters describing the physical and chemical properties of soil (co-inertia, p < 0.001; RV = 0.70). Using hierarchical classification, sites could be separated into four homogeneous groups and, using the ‘indicator value’ method, 46 indicator taxa characteristic of one or another of these groups were identified. We then used a formula that takes into account the abundance of indicator species and their respective indicator values to score soils from 1 to 20. IBQS was able to detect the effects of management practices on soil quality. Soil quality varied from 6 to 20 in forests, 7 to 9 in pastures and 2 to 9 in crops respectively. This suggests that well-managed crops and pastures may have better soil quality than some forests. Our results confirm that soil macro-invertebrates provide an integrative measure of soil quality and that the proposed index can be used either in short- or long-term monitoring, provided that it is calibrated and validated with respect to the regional context of the study.     

Olive oils improve lipid metabolism and increase antioxidant potential in rats fed diets containing cholesterol

The effect of olive oils on lipid metabolism and antioxidant activity was investigated on 60 male Wistar rats adapted to cholesterol-free or 1% cholesterol diets. The rats were divided into six diet groups of 10. The control group (control) consumed the basal diet (BD) only, which contained wheat starch, casein, cellulose, and mineral and vitamin mixtures. To the BD were added 10 g/100 g virgin (virg group) or Lampante (Lamp group) oils, 1 g/100 g cholesterol (chol group), or both (chol/virg group) and (chol/Lamp group). The experiment lasted 4 weeks. Plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides (TG), total phospholipids (TPH), HDL-phospholipids (HDL-PH), total radical-trapping antioxidative potential (TRAP), malondialdehyde lipid peroxidation (MDA), and liver TC were measured. Groups did not differ before the experiment. In the chol/virg and chol/Lamp vs chol group, the oil-supplemented diets significantly (P < 0.05) lessened the increase in plasma lipids due to dietary cholesterol as follows: TC (25.1 and 23.6%), LDL-C (39.3 and 34.7%), TG (19.3 and 17.0%), and TC in liver (36.0 and 35.1%) for the chol/virg and chol/Lamp group, respectively. The chol/virg and chol/Lamp diets significantly decreased the levels of TPH (24.7 and 21.2%; p < 0.05 in both cases) and HDL-PH (22.9 and 18.0%; p < 0.05 in both cases) for the chol/virg and chol/Lamp group, respectively. Virgin and Lampante oils in rats fed basal diet without cholesterol did not affect the lipid variables measured. Virgin, and to a lesser degree Lampante, oils have increased the plasma antioxidant activity in rats fed BD without cholesterol (an increase in TRAP, 20.6 and 18.5%; and a decrease in MDA, 23.2 and 11.3%, respectively). In the rats of chol/virg and chol/Lamp vs Chol diet groups the added oils significantly hindered the decrease in the plasma antioxidant activity (TRAP, 21.2 and 16.7%; and MDA, 27.0 and 22.3%, respectively). These results demonstrate that virgin, and to less degree Lampante, oils possess hypolipidemic and antioxidant properties. It is more evident when these oils are added to the diets of rats fed cholesterol. These positive properties are attributed mostly to the phenolic compounds of the studied oils.     

Effects of teflubenzuron on larvae and juveniles of the polychaete Capitella SP. B from Barcelona, Spain

The insecticide teflubenzuron is currently employed by salmon farms as an in-feed compound to control ectoparasite infestations, and its occurrence in the sediments surrounding the farms could thus pose a hazard to local infauna. The effect of teflubenzuron on mortality, growth and metamorphosis of larvae of cultured Capitella sp. B were investigated. This is a poecilogonic species with two hatching periods. Larvae and juveniles produced during the first and second releases were exposed to sediment spiked with teflubenzuron (0, 8.4, 25 and 41.8 μg/g dry wt sediment) for a 31 days period and daily observations were performed. Teflubenzuron incorporated to sediment produced larval and juvenile mortality and a strong reduction of body size from juveniles of the two release periods. Larval metamorphosis was delayed without a clear dose-response relationship. This preliminary study suggests that teflubenzuron is harmful to early developmental stages of Capitella sp. B. This fact has relevant ecological effects such as a delay in recruitment of individuals into natural populations.