Why are wheat yields stagnating in Europe? A comprehensive data analysis for France

The last two decades are witnessing a decline in the growth trend of cereal yields in many European countries. The present study analyses yield trends in France using various sources of data: national and regional statistics, scattered trials, results of agroclimatic models using climatic data. Effects in genetic changes through breeding, agronomy and climate are investigated as possible causes. Our results show that genetic progress has not declined but it was partly counteracted, from 1990 on, by climate change which in general is unfavorable to cereal yields in temperate climates because of heat stress during grain filling and drought during stem elongation. We cannot however, from the decade beginning in 2000, rule out agronomic causes, related to policy and economy, in particular the decline of legumes in the cereal rotations, replaced by oilseed rape and to a lesser extent the decrease in nitrogen fertilization.     

Long-term feeding ecology and habitat use in harbour porpoises Phocoena phocoena from Scandinavian waters inferred from trace elements and stable isotopes

Background  

We investigated the feeding ecology and habitat use of 32 harbour porpoises by-caught in 4 localities along the Scandinavian coast from the North Sea to the Barents Sea using time-integrative markers: stable isotopes (δ¹³C, δ¹⁵N) and trace elements (Zn, Cu, Fe, Se, total Hg and Cd), in relation to habitat characteristics (bathymetry) and geographic position (latitude).     

Lipopolysaccharides from Commensal and Opportunistic Bacteria: Characterization and Response of the Immune System of the Host Sponge Suberites domuncula

Marine sponges harbor a rich bacterioflora with which they maintain close relationships. However, the way these animals make the distinction between bacteria which are consumed to meet their metabolic needs and opportunistic and commensal bacteria which are hosted is not elucidated. Among the elements participating in this discrimination, bacterial cell wall components such as lipopolysaccharides (LPS) could play a role. In the present study, we investigated the LPS chemical structure of two bacteria associated with the sponge Suberites domuncula: a commensal Endozoicomonas sp. and an opportunistic Pseudoalteromonas sp. Electrophoretic patterns indicated different LPS structures for these bacteria. The immunomodulatory lipid A was isolated after mild acetic acid hydrolysis. The electrospray ionization ion-trap mass spectra revealed monophosphorylated molecules corresponding to tetra- and pentaacylated structures with common structural features between the two strains. Despite peculiar structural characteristics, none of these two LPS influenced the expression of the macrophage-expressed gene S. domuncula unlike the Escherichia coli ones. Further research will have to include a larger number of genes to understand how this animal can distinguish between LPS with resembling structures and discriminate between bacteria associated with it.     

Demospongic acids revisited

The well-known fatty acids with a Δ5,9 unsaturation system were designated for a long period as demospongic acids, taking into account that they originally occurred in marine Demospongia sponges. However, such acids have also been observed in various marine sources with a large range of chain-lengths (C(16)-C(32)) and from some terrestrial plants with short acyl chains (C(18)-C(19)). Finally, the Δ5,9 fatty acids appear to be a particular type of non-methylene-interrupted fatty acids (NMA FAs). This article reviews the occurrence of these particular fatty acids in marine and terrestrial organisms and shows the biosynthetic connections between Δ5,9 fatty acids and other NMI FAs.     

Detection of novel papillomaviruslike sequences in paraffin-embedded specimens of invasive and in situ squamous cell carcinomas from cats

OBJECTIVE: To detect and partially characterize papillomavirus (PV) DNA in squamous cell carcinoma (SCC) tumor specimens from cats. SAMPLE POPULATION: 54 formalin-fixed paraffinembedded skin biopsy specimens were examined. Specimens originated from Bowenoid in situ SCC (BISC; n = 21), invasive SCC (22), and skin affected by miscellaneous nonneoplastic conditions (11). PROCEDURES: Samples from each tissue block underwent DNA extraction after deparaffinization, and PCR assays were performed. Two sets of primers derived from PV E1 were used. The first set of primers was designed for the narrow-range PCR assay and was able to generate amplification products of feline PV (FePV), canine oral PV, or closely related PVs. The second set of primers was selected for the broad-range PCR assay because of its ability to amplify DNA from 64 human PVs. Sequence analysis of each amplified DNA was performed. RESULTS: 1 of the 21 specimens of BISC was positive for PV DNA on the basis of narrow-range PCR assay results, whereas all the other specimens (BISC, invasive SCC, and controls) had negative results for PV DNA. In contrast, 5 of 21 BISC specimens and 4 of 22 invasive SCC specimens were positive for PV DNA on the basis of broad-range PCR assay results. Sequence analysis revealed that only 1 specimen was infected by a virus closely related to classic FePV. In the 8 other specimens positive for PV DNA, DNA of unknown PVs was uncovered. CONCLUSIONS AND CLINICAL RELEVANCE: Bowenoid in situ SCC and invasive SCC of cats may be associated with PVs of genetic diversity.     

Immunisation with a combination of two complementary feline calicivirus strains induces a broad cross-protection against heterologous challenges

Feline calicivirus (FCV) is characterised by a high degree of antigenic variation potentially compromising vaccine efficacy. Inclusion of several FCV strains or antigens in current vaccines could be a means to improve protection against antigenically distinct isolates. This study evaluated the synergy between two FCV strains (FCVG1 and FCV431) by comparing immunity induced by either strain with that provided by a combination of the two strains against an heterologous challenge with antigenically distant FCV strains (FCV393 and FCV220). Thirty-two SPF kittens were randomly allocated to four groups of eight cats in each group. Groups B, C and D cats were vaccinated once subcutaneously with strains FCVG1, FCV431, and FCVG1 + FCV431, respectively. Each kitten received a total dose of 10(3.4) CCID50 of FCV. Control group A was not immunised. On day 31, four cats from each group were challenged oronasally with FCV220 and four cats with FCV393. Following challenge, the cats were monitored for clinical signs, viral shedding and antibody responses. FCV220 and FCV393 induced severe clinical signs in control cats typical of FCV infection. Immunisation with both strains mixed together induced higher neutralizing antibody titres against FCV220 and FCV393 strains on average. Protection was observed in all groups, however combination of the two strains resulted in a better clinical protection and reduction of virus shedding after heterologous challenge. A moderate correlation was observed between neutralizing antibody titres at the time of challenge and protection against clinical signs. These results indicated that vaccines combining antigens from different FCV strains may induce a broader heterologous protection.     

Influence of agricultural soils on the growth and reproduction of the bio-indicator Folsomia candida

Soil organisms have been recommended as bio-indicators of soil quality due to their sensitivity to anthropogenic influences and their high degree of site-specificity. The objectives of this study were to determine if the relationship between the soil Collembola, Folsomia candida, and forest soil could be extended to other soils and, if not, to determine the relationship between its life parameters and soils from the different phases of an agricultural rotation sequence. A comparison of growth, reproduction and survival of 1 day old neonates and 10 day old juveniles subjected to a series of different soils (composted manure, pasture soil, forest soil, sand alone, and sand supplemented with yeast) established that the association between F. candida and forest soil quality cannot be automatically transferred to soils from other ecosystems. The test also showed that neonate (1 d) individuals were more sensitive to the different soil treatments than 10 d old juveniles and should be used in future tests. On this basis, neonate F. candida individuals were used to determine if the species could be employed to characterize the agricultural soils from the different phases of an organic or conventional rotation sequence. Results demonstrated that changes in body growth and reproduction constituted suitable criteria to characterize the soil quality of these different phases. The research required to develop these results as a standard bio-indicator test of agricultural soil quality is discussed.     

Non‐spherical pearl layers in the Polynesian ‘black‐lipped’ Pinctada margaritifera: The non‐nacreous deposits compared to microstructure of the shell growing edge

Cultivated pearls frequently exhibit morphological irregularities making obvious that mineral deposition was irregularly distributed onto nucleus surface. Taking advantage of experimental cultivations with short durations (from 10 days to few months), these irregular deposits predating occurrence of the nacre were investigated in Polynesian pearls by biochemical characterizations and a series of physical methods. Diversity in the resulting data suggests that various in‐depth alterations of the biomineralization mechanism may have occurred during the grafting process, leading to diversity in the biochemical pathways to nacreous deposition. This allows a precise discussion of current views about pearl formation. The “reversed shell theory” is formally disproved through point to point comparison with development of the shell growing edge. Similarity of pearl formation with “regeneration” or “shell repair” is also discussed, emphasizing the differences between these concepts.     

Hemagglutinating activity associated with bovine herpesvirus type 1

Using C57BL/HPB mouse erythrocytes, hemagglutination has been observed with the Los Angeles and Colorado-1 strains of bovine herpesvirus type 1 and with 12 other Canadian field isolates as well. The specificity of the hemagglutination observed with the viral strains has been confirmed by a hemagglutination-inhibition assay.     

Nitrogen isotopic composition of leached nitrate and soil organic matter as an indicator of denitrification in a sloping drained agricultural plot and adjacent uncultivated riparian buffer strips

In the small, agricultural, artificially drained Orgeval watershed δ¹⁵N values of leached nitrates and soil organic nitrogen were found to be significantly higher than the primary nitrogen (N) sources from which they are derived, namely, synthetic fertilizers, atmospheric deposition, and symbiotic or nonsymbiotic N₂ fixation (all with δ¹⁵N close to zero). In vertical soil profiles, the δ¹⁵N of organic N increased with depth, reaching higher values (up to 8‰) particularly at stations that were frequently waterlogged as judged from ochre iron traces, such as downhill field sites or in riparian buffer strips. Nitrification, volatilization, and denitrification are the main fractionating processes able to modify the isotopic composition of soil N. Using a newly designed algorithm for calculating the equilibrium isotopic composition of all soil N species, resulting from the average annual balance of their transformations, we show that the observed trends can be explained by the action of denitrification. We suggest that the isotopic composition of soil organic N can be used as a semiquantitative indicator of the intensity of denitrification integrated over century-long periods.