Quantitative transmission characteristics of different H5 low pathogenic avian influenza viruses in Muscovy ducks

EU annual serosurveillance programs show that domestic duck flocks have the highest seroprevalence of H5 antibodies, demonstrating the circulation of notifiable avian influenza virus (AIV) according to OIE, likely low pathogenic (LP). Therefore, transmission characteristics of LPAIV within these flocks can help to understand virus circulation and possible risk of propagation. This study aimed at estimating transmission parameters of four H5 LPAIV (three field strains from French poultry and decoy ducks, and one clonal reverse-genetics strain derived from one of the former), using a SIR model to analyze data from experimental infections in SPF Muscovy ducks. The design was set up to accommodate rearing on wood shavings with a low density of 1.6 ducks/m²: 10 inoculated ducks were housed together with 15 contact-exposed ducks. Infection was monitored by RNA detection on oropharyngeal and cloacal swabs using real-time RT-PCR with a cutoff corresponding to 2–7 EID50. Depending on the strain, the basic reproduction number (R₀) varied from 5.5 to 42.7, confirming LPAIV could easily be transmitted to susceptible Muscovy ducks. The lowest R₀ estimate was obtained for a H5N3 field strain, due to lower values of transmission rate and duration of infectious period, whereas reverse-genetics derived H5N1 strain had the highest R₀. Frequency and intensity of clinical signs were also variable between strains, but apparently not associated with longer infectious periods. Further comparisons of quantitative transmission parameters may help to identify relevant viral genetic markers for early detection of potentially more virulent strains during surveillance of LPAIV.     

Abrupt decrease in tropical Pacific sea surface salinity at end of Little Ice Age

A 420-year history of strontium/calcium, uranium/calcium, and oxygen isotope ratios in eight coral cores from the Great Barrier Reef, Australia, indicates that sea surface temperature and salinity were higher in the 18th century than in the 20th century. An abrupt freshening after 1870 occurred simultaneously throughout the southwestern Pacific, coinciding with cooling tropical temperatures. Higher salinities between 1565 and 1870 are best explained by a combination of advection and wind-induced evaporation resulting from a strong latitudinal temperature gradient and intensified circulation. The global Little Ice Age glacial expansion may have been driven, in part, by greater poleward transport of water vapor from the tropical Pacific.     

Rapid pneumococcal evolution in response to clinical interventions

Epidemiological studies of the naturally transformable bacterial pathogen Streptococcus pneumoniae have previously been confounded by high rates of recombination. Sequencing 240 isolates of the PMEN1 (Spain(23F)-1) multidrug-resistant lineage enabled base substitutions to be distinguished from polymorphisms arising through horizontal sequence transfer. More than 700 recombinations were detected, with genes encoding major antigens frequently affected. Among these were 10 capsule-switching events, one of which accompanied a population shift as vaccine-escape serotype 19A isolates emerged in the USA after the introduction of the conjugate polysaccharide vaccine. The evolution of resistance to fluoroquinolones, rifampicin, and macrolides was observed to occur on multiple occasions. This study details how genomic plasticity within lineages of recombinogenic bacteria can permit adaptation to clinical interventions over remarkably short time scales.     

Predicting likelihood of in vivo chemotherapy response in canine lymphoma using ex vivo drug sensitivity and immunophenotyping data in a machine learning model

We report a precision medicine platform that evaluates the probability of chemotherapy drug efficacy for canine lymphoma by combining ex vivo chemosensitivity and immunophenotyping assays with computational modelling. We isolated live cancer cells from fresh fine needle aspirates of affected lymph nodes and collected post‐treatment clinical responses in 261 canine lymphoma patients scheduled to receive at least 1 of 5 common chemotherapy agents (doxorubicin, vincristine, cyclophosphamide, lomustine and rabacfosadine). We used flow cytometry analysis for immunophenotyping and ex vivo chemosensitivity testing. For each drug, 70% of treated patients were randomly selected to train a random forest model to predict the probability of positive Veterinary Cooperative Oncology Group (VCOG) clinical response based on input variables including antigen expression profiles and treatment sensitivity readouts for each patient's cancer cells. The remaining 30% of patients were used to test model performance. Most models showed a test set ROC‐AUC > 0.65, and all models had overall ROC‐AUC > 0.95. Predicted response scores significantly distinguished (P < .001) positive responses from negative responses in B‐cell and T‐cell disease and newly diagnosed and relapsed patients. Patient groups with predicted response scores >50% showed a statistically significant reduction (log‐rank P < .05) in time to complete response when compared to the groups with scores <50%. The computational models developed in this study enabled the conversion of ex vivo cell‐based chemosensitivity assay results into a predicted probability of in vivo therapeutic efficacy, which may help improve treatment outcomes of individual canine lymphoma patients by providing predictive estimates of positive treatment response.     

Effect of intrinsic and extrinsic factors on the interaction of plant pectin methylesterase and its proteinaceous inhibitor from kiwi fruit

A proteinaceous pectin methylesterase inhibitor (PMEI) was isolated from kiwi fruit (Actinidia chinensiscv. Hayward) and purified by affinity chromatography on a cyanogen bromide (CNBr) Sepharose 4B-orange PME column. The optimal pH of banana PME activity was 7.0, whereas that for carrot and strawberry PME activity was 9.0. The optimal pH for the binding between kiwi fruit PMEI and these PMEs was 7.0. The kiwi fruit PMEI has a different affinity for PME depending on the plant source. The inhibition kinetics of kiwi fruit PMEI to banana and strawberry PME followed a noncompetitive type, whereas that to carrot PME followed a competitive type. The kiwi fruit PMEI was mixed with banana, carrot, and strawberry PME to obtain PMEI-PME complexes, which were then subjected to thermal (40-80 degrees C, atmospheric pressure) or high-pressure (10 degrees C, 100-600 MPa) treatment. Experimental data showed that the PMEI-PME complexes were easily dissociated by both thermal and high-pressure treatments.     

Stabilization of caffeic acid derivatives in Echinacea purpurea L. glycerin extract

Recent work has shown that enzymatic degradation and oxidation of cichoric acid and other caffeic derivatives occurs in Echinacea preparations. However, very little is known as to the means of stabilizing these phytopreparations. To stabilize the glycerin extract of Echinacea purpurea, we have evaluated the effects of 3 natural antioxidants (citric acid, malic acid, and hibiscus extract) on the stability of the major caffeic acid derivatives (caftaric acid, caffeic acid, cichoric acid, and 2-O-feruloyl-tartaric acid). Chlorogenic acid, which normally occurs in an ethanol extract of E. purpurea, was not present in the glycerin extract. The caffeic acid derivatives, with the exception of 2-O-feruloyl-tartaric acid, were subject to degradation in the control sample. 2-O-Feruloyl-tartaric acid was stable during the whole testing period. All antioxidant treatments greatly improved the stability of caffeic acid derivatives. Stability was dependent upon the concentration of antioxidant added.     

Denitrification and nitrous oxide to nitrous oxide plus dinitrogen ratios in the soil profile under three tillage systems

There is a growing interest in the adoption of conservation tillage systems [no-till (NT) and reduced tillage (RT)] as alternatives to conventional tillage (CT) systems. A 2-year study was conducted to investigate possible environmental consequences of three tillage systems on a 2.4-ha field located at Macdonald Research Farm, McGill University, Montreal. The soil was a sandy loam (0.5 m depth) underlain by a clay layer. Treatments consisted of a factorial combination of CT, RT, and NT with the presence or absence of crop residue. Soil NO₃^--N concentrations tended to be lower in RT than NT and CT tillage treatments. Denitrification and N₂O emissions were similar among tillage systems. Contrary to the popular assumption that denitrification is limited to the uppermost soil layer (0–0.15 m), large rates of N₂O production were measured in the subsurface (0.15–0.45 m) soil, suggesting that a significant portion of produced N₂O may be missed if only soil surface gas flux measurements are made. The N₂O mole fraction (N₂O:N₂O+N₂) was higher in the drier season of 1999 under CT than in 2000, with the ratio occasionally exceeding 1.0 in some soil layers. Dissolved organic C concentrations remained high in all soil depths sampled, but were not affected by tillage system.     

Marine Fish Larvae Feeding: Formulated Diets or Live Prey?

In the rearing of larval marine fish, any diet that reduces dependance on live prey production is of technical and economic interest. Weaning juveniles with a completely developed digestive tract to a conventional diet, (i.e., "late weaning") can be successful in any marine fish species. For example, weaning one-month-old sea bass (20 mg) to the study's reference diet, Sevbar, resulted in over 85% survival (40% from hatching) and 1.25 g fish at day 90 (at 19 C)
In contrast, "early weaning" of larvae to special microdiets during the first month is still difficult. The best way to reduce live prey utilization in sea bass is to wean larvae at about 3–4 mg in size (day 20). If weaning could be accomplished 15 days earlier, Artemia savings could be as high as 80%. However, this introduces risks relative to growth retardation (30% weight loss) and lower juvenile quality, including greater size variability and skeletal abnormalities. Similar results have been obtained with commercial microparticles (Fry Feed Kyowa) and experimental microbound diets (MBD) made from raw materials (alginate MBD) or preferably from freeze-dried protein sources (zein MBD).
Total replacement of live prey is still impossible in marine fish. Sea bass larvae fed formulated diets exclusively from first feeding (0.3 mg larval wet weight), or even from their second week of life onwards, exhibited low survival and poor growth. Better results can be obtained when formulated diets are used in combination with live prey from first feeding, although the optimal ratio of live prey to formulated diet is still to be specified.     

Cellular Impact of Metal Trace Elements in Terricolous Lichen Diploschistes muscorum (Scop.) R. Sant. – Identification of Oxidative Stress Biomarkers

The purpose of this research is to present toxic effects of some heavy metals (cadmium, lead and zinc) on lichen physiology. In the North of France, those metals are concentrated for example in industrial polluted soils near metallurgic plants and waste dumps. Our investigations were conducted on Diploschistes muscorum (Scop.) R. Sant, a terricolous lichen growing on previously quoted soils as well as on non-contaminated ones. Different stress parameters were investigated as potassium leakage – which is related to the loss of membrane integrity – and oxidative stress through following parameters: malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD). It seems, therefore, that heavy metals induce oxidative stress in this lichen, in which we found membrane damage and enhancement of SOD activity and GSH concentrations. With regard to very high concentrations of Cd, Pb and Zn, a resistance involving antioxidant mechanisms limits the expected damage. Those mechanisms involve GSH, SOD as well as secondary metabolites, which have this resistance property. This study is a first step of investigation to use – in the future– physiological parameters as tool for environment assessment.