Distribution of VKORC1 single nucleotide polymorphism in wild Rattus norvegicus in France

BACKGROUND: Anticoagulant rodenticides are commonly used to control rodent pests all over the world. These pesticides inhibit one enzyme of the vitamin K cycle, Vkorc1, and thus prevent blood clotting and cause death by haemorrhage. Resistance to anticoagulants was first observed in Scotland in 1958, and more potent anticoagulants have been developed to overcome this obstacle. Unfortunately, these chemicals are very toxic and cannot be used everywhere. Some authors have shown that resistance to anticoagulants seems closely linked with single nucleotide polymorphism (SNP) in the Vkorc1 gene. RESULTS: This study draws a map of SNP and haplotypes found in Vkorc1 in rats from different areas of France. Some of them had never been described before. Moreover, the Y139F mutation, described previously in France and Belgium, is the most frequent in France. This mutation is known to be associated with a strong resistance to anticoagulants, and it was found in 28% of the samples. CONCLUSION: This biomolecular approach to studying and detecting resistance is easier to carry out than the phenotypic approach measuring blood coagulation time because it can be conducted on biological samples from dead animals, and it is less dangerous for the operator. Copyright © 2009 Society of Chemical Industry     

Ephemeral-habitat colonization and neotropical species richness of <Emphasis Type="Italic">Caenorhabditis</Emphasis> nematodes

Background

The drivers of species co-existence in local communities are especially enigmatic for assemblages of morphologically cryptic species. Here we characterize the colonization dynamics and abundance of nine species of Caenorhabditis nematodes in neotropical French Guiana, the most speciose known assemblage of this genus, with resource use overlap and notoriously similar external morphology despite deep genomic divergence.

Methods

To characterize the dynamics and specificity of colonization and exploitation of ephemeral resource patches, we conducted manipulative field experiments and the largest sampling effort to date for Caenorhabditis outside of Europe. This effort provides the first in-depth quantitative analysis of substrate specificity for Caenorhabditis in natural, unperturbed habitats.

Results

We amassed a total of 626 strain isolates from nine species of Caenorhabditis among 2865 substrate samples. With the two new species described here (C. astrocarya and C. dolens), we estimate that our sampling procedures will discover few additional species of these microbivorous animals in this tropical rainforest system. We demonstrate experimentally that the two most prevalent species (C. nouraguensis and C. tropicalis) rapidly colonize fresh resource patches, whereas at least one rarer species shows specialist micro-habitat fidelity.

Conclusion

Despite the potential to colonize rapidly, these ephemeral patchy resources of rotting fruits and flowers are likely to often remain uncolonized by Caenorhabditis prior to their complete decay, implying dispersal-limited resource exploitation. We hypothesize that a combination of rapid colonization, high ephemerality of resource patches, and species heterogeneity in degree of specialization on micro-habitats and life histories enables a dynamic co-existence of so many morphologically cryptic species of Caenorhabditis.

     

Time course and specificity of lipolysis in Swiss cheese

Controlling lipolysis in cheese is necessary to ensure the formation of desirable flavor. To get a better understanding of the mechanism of lipolysis in Swiss cheese, cheeses were manufactured with and without (control) the addition of Propionibacterium freudenreichii. Products of lipolysis were quantified throughout ripening. Half of the free fatty acids (FFA) released in milk (3.66 mg/g fat), in particular the short-chain FFA, were lost in the whey during curd drainage, whereas diglycerides and monoglycerides were retained within the curd. P. freudenreichii was responsible for the release of most FFA during ripening (10.84 and 0.39 mg/g fat in propionibacteria-containing and control cheeses, respectively). Indices of lipolysis displayed low specificity. All types of FFA were released, but butyric and palmitic acids more significantly, which could be due to a low sn-1,3 regioselectivity. All glycerides were hydrolyzed in the following order: monoglycerides>diglycerides>triglycerides. The results of this study show the quantitative and qualitative contributions of the different lipolytic agents to Swiss cheese lipolysis.     

Moisture diffusion coefficient of reaction woods: compression wood of Picea abies L. and tension wood of Fagus sylvatica L.

The moisture diffusion coefficient of compression wood in spruce (P. abies) and tension wood in beech (F. sylvatica) was examined. The results indicated that the diffusion coefficient measured under steady-state condition (cup method) could well characterize the drying kinetics of the reaction woods. The compression wood offered more resistance to the moisture diffusivity when compared with the corresponding normal wood. The thick cell wall rich in lignin explains the small mass diffusivity in compression wood. In contrast, the mass diffusivity in beech is almost always higher in tension wood than in normal wood, in spite of similar density values. The high moisture diffusion in tension wood can be explained by the ease of bound water diffusion in the gelatinous layers (G-layers).     

Effect of a novel animal milk oligosaccharide biosimilar on macronutrient digestibility and gastrointestinal tolerance,fecal metabolites,and fecal microbiota of healthy adult cats

GNU100 is a novel animal milk oligosaccharide (AMO) biosimilar. In a recent in vitro fermentation study, GNU100 was shown to be fermentable by feline gastrointestinal microbiota and lead to increased short-chain fatty acid production. Our objectives herein were to evaluate the palatability, safety, and gastrointestinal tolerance of GNU100 in healthy adult cats. Exploratory end-points were measured to assess utility. In study 1, 20 adult cats were used to test the palatability of diets containing 0% or 1% GNU100. In study 2, 32 (mean age = 1.9 yr; mean body weight = 4.6 kg) male (n = 12) and female (n = 20) adult cats were used in a completely randomized design. After a 2-wk baseline, cats were assigned to one of the following treatment groups and fed for 26 wk: control (CT, no GNU100), low dose (LD, 0.5% GNU100), medium dose (MD, 1.0% GNU100), and high dose (HD, 1.5% GNU100). On weeks 2, 4, and 26, fresh fecal samples were collected for the measurement of stool quality and immune and inflammatory markers and on weeks 2 and 4 for microbiota and metabolites. On week 4, total feces were collected to measure apparent total tract macronutrient digestibility. On weeks 2, 4, and 26, blood samples were collected for serum chemistry, hematology, and inflammatory marker measurement. The palatability test showed that 1% GNU100 was strongly preferred (P < 0.05), with GNU100 having a 17.6:1 consumption ratio compared with control. In the long-term study, all cats remained healthy, without any signs of gastrointestinal intolerance or illness. All diets were well accepted, resulting in similar (P > 0.05) food intake, fecal characteristics, immunoglobulin A, and calprotectin, and dry matter, organic matter, fat, and crude protein digestibilities. Fecal butyrate was greater (P = 0.02) in cats fed HD than cats fed LD or MD. Fecal indole was lower (P = 0.02) in cats fed HD than cats fed LD. Cats fed CT had a higher (P = 0.003) relative abundance of Actinobacteria than cats fed LD. The relative abundance of Peptococcus was impacted by diet and time. At 4 wk, Campylobacter was lower in fecal samples of cats fed HD. Overall, the data suggest that dietary GNU100 supplementation was highly palatable, well tolerated, did not cause detrimental effects on fecal quality or nutrient digestibility, increased fecal butyrate concentrations, and reduced fecal indole concentrations, supporting the safety of GNU100 for inclusion in feline diets and suggesting potential benefits on gastrointestinal health of cats.     

The onset of the rainy season and farmers’ sowing strategy for pearl millet cultivation in Southwest Niger

A multi-year (2004-2009) field survey of on-farm sowing practices in 10 villages located in south-west Niger close to Niamey, is analysed to investigate the relationships (i) between rainfall and the sowing date of pearl millet and the risk of sowing failure, (ii) between sowing and meteorological/agro-climatic onset dates, (iii) between sowing/onset dates, and simulated and observed yield/biomass at the end of the season. Even if some villages sow without any synchronous or anterior rainfall, most parcels (73% out of the 1551 available cases) are sown during and just after a 2-day wet spell receiving at least 10 mm. In fact, there is a strong correlation (r = 0.82-0.95 depending on onset definition) between the spatial averages of onset and of sowing dates. Most of the failed sowings (≈22% of total sowings) are related to dry spells lasting at least 7 days after an initial 2-day wet spell receiving less than 10 mm. Simulations with the “Système d’Analyse Régionale des Risques Agronomiques - version Habillée” crop model show that the ideal sowing date, retrospectively computed as the one maximizing simulated yield, is on average about 6 days later than the observed one. Despite the large inter-village variance and the relatively weak inter-annual signal in onset dates and seasonal amounts, there is a tendency for weaker yields and especially weaker amounts of biomass for late onset. But crop simulations show that sowing very early, as for example during or just after the first wet spell when at least 90% of rainfall stations receive simultaneously at least 1 mm in two consecutive days (i.e. meteorological onset), does not necessarily maximize simulated yield because of the high risk of long-lasting post-onset dry spells. The farmers’ strategy, that is sowing their field during or just after the first significant wet spell, is combined with the use of photoperiodic varieties to provide the best-suited response to the temporal and spatial variability of onset of the rainy season.     

National inventory and prioritization of crop wild relatives: case study for Benin

Species prioritization is a crucial step in any development of conservation strategy, especially for crop wild relatives (CWR), since financial resources are generally limited. This study aimed at: assessing the biodiversity of crop wild relatives in Benin and identifying priority species for active conservation. Data were collected through literature review to establish an exhaustive list of CWR in Benin. Eight prioritization criteria and different prioritization systems were used. The top 50 species obtained by each of these methods were identified and twenty final top CWR were shortlisted as those occurring as priority across methods. A total of 266 plant species belonging to 65 genera and 36 families were identified. The most represented are: Cyperaceae (12.50 %), Leguminosae-Papilionoideae (11.87 %), Convolvulaceae (11.25 %), Poaceae (10.31 %), Asteraceae (7.81 %), Solanaceae (6.87 %) and Dioscoreaceae (5.31 %). Among the 20 species of highest priority for conservation, Manihot glaziovii Müll. Arg. and Piper guineense Schumach. et Thonn., appeared as the most represented species on top of the list.     

First report of the sexual stage of the flax pathogen Mycosphaerella linicola in France and its impact on pasmo epidemiology

We performed a 3-year field survey in France to characterize the dynamics of sexual reproduction in Mycosphaerella linicola, the causal agent of pasmo, during the interepidemic period. Cohorts of fruiting bodies were sampled from linseed straw during the autumn and winter and carefully observed, focusing on pseudothecia, asci, and ascospores. A sequence of experimental steps corresponding to Koch's postulates confirmed in July 2014, for the first time in France and continental Europe, the widespread presence of the sexual stage of M. linicola in plant host tissues. The developmental dynamics of pseudothecia on straw, expressed as the change over time in the percentage of mature pseudothecia, was similar in all three years. Pseudothecia appeared in late summer, with peak maturity reached in October. A temporal shift, thought to be due to early autumn rainfall, was highlighted in one of the three years. These observations suggest that sexual reproduction plays a significant role in the epidemiology of pasmo in France. A resurgence of M. linicola infections in spring flax is thought to have occurred in recent years, due to the increase in the area under flax. The presence of the sexual stage of this pathogen probably increased the quantitative impact of residues of winter linseed (used for oil) and flax straw (left on the soil for retting and used for fibres) as an interepidemic “brown bridge”. This case study highlights how certain parts of a disease cycle, in this case the sexual phase, can become crucial due to changes in production conditions.