A tool for testing integrated pest management strategies on a tritrophic system involving pollen beetle, its parasitoid and oilseed rape at the landscape scale

The intensification of agriculture has led to a loss of biodiversity and subsequently to a decrease in ecosystem services, including regulation of pests by natural enemies. Biological regulation of pests is a complex process affected by both landscape configuration and agricultural practices. Although modeling tools are needed to design innovative integrated pest management strategies that consider tritrophic interactions at the landscape scale, landscape models that consider agricultural practices as levers to enhance biological regulation are lacking. To begin filling this gap, we developed a grid-based lattice model called Mosaic-Pest that simulates the spatio-temporal dynamics of Meligethes aeneus, a major pest of oilseed rape, and its parasitoid, Tersilochus heterocerus through a landscape that changes through time according to agricultural practices. The following agricultural practices were assumed to influence the tritrophic system and were included in the model: crop allocation in time and space, ploughing, and trap crop planting. To test the effect of agricultural practices on biological regulation across landscape configurations, we used a complete factorial design with the variables described below and ran long-term simulations using Mosaic-Pest. The model showed that crop rotation and the use of trap crop greatly affected pollen beetle densities and parasitism rates while ploughing had only a small effect. The use of Mosaic-Pest as a tool to select the combination of agricultural practices that best limit the pest population is discussed.     

Perennial O. sativa × O. rufipogon interspecific hybrids: I. Photosynthetic characteristics and their inheritance

A survey of 24 wild Oryza accessions identified Oryza australiensis and Oryza rufipogon as potential sources of enhanced photosynthetic rate for introgression into cultivated rice. Photosynthetic capacity per unit leaf area (CER) was associated with leaf N content but not with leaf chlorophyll concentration, flag leaf area, or specific leaf area. Eight fertile, perennial F₁ hybrids between O. sativa and O. rufipogon were grown in non-flooded soil, and CER was measured at flowering under saturating light. Two F₁ hybrids had greater CER than the average of 26.1 μmol m² s⁻¹. The F₂ progeny from these hybrids were screened for CER in the field, and segregants with even greater rates of photosynthesis were selected. The basis of high photosynthetic rate in the F₂ populations was not leaf thickness or leaf chlorophyll content. One F₂ line had exceptionally high CER and stomatal conductance. Broad-sense heritability on an individual plant basis for CER in two F₂ populations was 0.44 and 0.37. A highly significant offspring-parent regression of 0.89 for CER was observed in a replicated field evaluation (four blocks, five plants per plot) of 20 vegetatively propagated F₂ selections and their F₃ seedling progeny. Broad-sense heritability for CER on a plot-mean basis was estimated as 0.74 for both selected F_2:3 families and for the selected F₂ clones. Genetic resources in the genus Oryza may represent a source of alleles to increase leaf photosynthetic rate in the cultivated species, which we have demonstrated to be a heritable, though environmentally variable, trait in an O. sativa/O. rufipogon population.     

User-friendly extraction and multistage tandem mass spectrometry based analysis of lipid-linked oligosaccharides in microalgae

Background

Protein N-glycosylation is initiated within the endoplasmic reticulum through the synthesis of a lipid-linked oligosaccharides (LLO) precursor. This precursor is then transferred en bloc on neo-synthesized proteins through the action of the oligosaccharyltransferase giving birth to glycoproteins. The N-linked glycans bore by the glycoproteins are then processed into oligomannosides prior to the exit of the glycoproteins from the endoplasmic reticulum and its entrance into the Golgi apparatus. In this compartment, the N-linked glycans are further maturated in complex type N-glycans. This process has been well studied in a lot of eukaryotes including higher plants. In contrast, little information regarding the LLO precursor and synthesis of N-linked glycans is available in microalgae.

Methods

In this report, a user-friendly extraction method combining microsomal enrichment and solvent extractions followed by purification steps is described. This strategy is aiming to extract LLO precursor from microalgae. Then, the oligosaccharide moiety released from the extracted LLO were analyzed by multistage tandem mass spectrometry in two models of microalgae namely the green microalgae, Chlamydomonas reinhardtii and the diatom, Phaeodactylum tricornutum.

Results

The validity of the developed method was confirmed by the analysis of the oligosaccharide structures released from the LLO of two xylosyltransferase mutants of C. reinhardtii confirming that this green microalga synthesizes a linear Glc₃Man₅GlcNAc₂ identical to the one of the wild-type cells. In contrast, the analysis of the oligosaccharide released from the LLO of the diatom P. tricornutum demonstrated for the first time a Glc₂Man₉GlcNAc₂ structure.

Conclusion

The method described in this article allows the fast, non-radioactive and reliable multistage tandem mass spectrometry characterization of oligosaccharides released from LLO of microalgae including the ones belonging to the Phaeodactylaceae and Chlorophyceae classes, respectively. The method is fully adaptable for extracting and characterizing the LLO oligosaccharide moiety from microalgae belonging to other phyla.

     

Effects of adjuvant-augmented germling vaccines in turkey poults challenged with Aspergillus fumigatus

Turkey poults were vaccinated with combinations of two different germling preparations and three adjuvants (N-acetylmuranyl-L-alanyl-D-isoglutamine, Pasteurella multocida lipopolysaccharide [LPS], and avridine) at 1 and 2 weeks of age, and their immunity was challenged by sublethal exposure to aerosols of Aspergillus fumigatus conidia at 1 month of age. Fewer turkeys in the groups given vaccines prepared from germlings grown on Dorset's and Henley's medium (D&H) had organisms in lung tissue at 2 weeks after challenge exposure as compared with those vaccinated with germling grown on neopeptone dialysate (Neo). The LPS of P. multocida appeared to be the most efficacious of the adjuvants in the D&H vaccine group, as A. fumigatus was isolated from only one of eight turkeys in this group; the number of organisms per gram of lung tissue was low compared with other vaccine groups at 2 weeks after challenge exposure; and poults given D&H vaccine with LPS as adjuvant had less-severe lung lesions than other groups. These differences in lung lesions were more marked at 2 weeks than at 8 weeks after challenge exposure. The only difference among other parameters in the vaccinated turkeys was lower heterophil counts in the turkeys given D&H-prepared vaccines than in unvaccinated controls. This was probably due to less-severe infections resulting from protective effects of these vaccines.     

Kinematics of late paleozoic continental collision between laurentia and gondwana

In the Appalachians, late Paleozoic Alleghanian orogenesis is widely regarded as resulting from dextral oblique collision between irregular margins of Gondwana and Laurentia. However, this relative plate motion cannot account for coeval convergence in the Ouachitas and Variscides and is incompatible with some tectonic transport indicators in the Appalachians. An alternative kinematic model is proposed in which early sinistral transpression in the Appalachians is followed by counterclockwise rotation of Gondwana and the development of a system of dextral strike-slip faults extending from southern Europe to Alabama.     

Antiviral effectiveness of butylated hydroxytoluene against pseudorabies (Aujeszky's disease) virus in cell culture, mice, and swine

Butylated hydroxytoluene (BHT) was evaluated for antiviral effectiveness on pseudorabies virus (PRV) in cell culture, mice, and swine. When relatively small amounts of BHT were mixed with PRV and incubated at 37 C for 30 or 60 minutes before inoculation into cell cultures, the cell cultures did not become infected with virus. The PRV was not infectious when the virus was treated with BHT and then inoculated intraperitoneally into mice, but was infectious when BHT and PRV were inoculated simultaneously or when BHT was inoculated either 30 or 60 minutes before PRV. Swine fed BHT-medicated feed for 10 days before they were intranasally exposed with virulent PRV did not have overt signs of pseudorabies, had a lower concentration of PRV in nasal mucus than did control swine, and had acceptable blood enzyme and cholesterol concentrations during the experiment. The BHT was detected in tissues of 2 swine after they were fed BHT-medicated feed for 10 days, and higher concentrations of BHT were detected in tissues of 3 swine given BHT feed for 29 days.     

Perennial hybrids of Oryza sativa × Oryza rufipogon: Part II. Carbon exchange and assimilate partitioning

Oryza species differ in their degree of perenniality, which has implications for patterns of carbon distribution in the plant. Interspecific F₁ hybrids of Oryza sativa × Oryza rufipogon were compared with their parental lines to assess whether they differed in assimilate storage and distribution at flowering and after maturity of the first cohort of panicles. The F₁ hybrids varied widely in plant type, but on average they had small plant size and low main tiller weights at anthesis, similar to O. rufipogon, and had intermediate tiller numbers and final single plant weights similar to cultivated rice. O. rufipogon had higher concentrations of starch in stems at anthesis, while interspecific hybrids exhibited comparatively low leaf, stem + sheath, and root sugar concentrations. Near anthesis, substantial ¹⁴C label remained in the source (flag) leaf in O. sativa and F₁ hybrids, while in O. rufipogon more label was exported to sink tissues. The hybrids partitioned more ¹⁴C label to panicles than did cultivated rice and less to leaf sheaths than either parent. Hybrids that had previously been identified as having above-average carbon exchange rates (CER) did not differ consistently from the low-CER hybrids in carbohydrate dynamics. The cultivated species itself maintains some perennial features, and changes in these traits might increase productivity.     

Anchoring tick salivary anti-complement proteins IRAC I and IRAC II to membrane increases their immunogenicity

Tick salivary proteins are promising targets for the development of anti-tick vaccines. Recently, we described two paralogous anti-complement proteins, called Ixodes ricinus anti-complement (IRAC) proteins I and II, that are co-expressed in tick I. ricinus salivary glands. However, our previous attempts to immunize rabbits against IRAC via infection with recombinant Bovine herpesvirus 4 (BoHV-4) vectors invariably failed although both recombinants expressed high levels of functional IRAC proteins in vitro. As IRAC are soluble monovalent antigens, one of the possible explanations is that monovalent ligation of the B-cell receptor induces receptor activation but fails to promote antigen presentation, a phenomenon that is thought to induce a state of B-cell tolerance. In the present study, we tried to increase IRAC immunogenicity by expressing them as oligovalent antigens. To this end, IRAC were fused to membrane anchors and BoHV-4 vectors expressing these recombinant forms were produced. The immunization potentials of recombinant viruses expressing either secreted or transmembrane IRAC proteins were then compared. While the former did not induce a detectable immune response against IRAC, the latter led to high titres of anti-IRAC antibodies that only marginally affected tick blood feeding. All together, the data presented in this study demonstrate that the immunogenicity of a soluble antigen can be greatly improved by anchoring it in membrane.