Genetic resistance to rhabdovirus infection in teleost fish is paralleled to the derived cell resistance status

Genetic factors of resistance and predisposition to viral diseases explain a significant part of the clinical variability observed within host populations. Predisposition to viral diseases has been associated to MHC haplotypes and T cell immunity, but a growing repertoire of innate/intrinsic factors are implicated in the genetic determinism of the host susceptibility to viruses. In a long-term study of the genetics of host resistance to fish rhabdoviruses, we produced a collection of double-haploid rainbow trout clones showing a wide range of susceptibility to Viral Hemorrhagic Septicemia Virus (VHSV) waterborne infection. The susceptibility of fibroblastic cell lines derived from these clonal fish was fully consistent with the susceptibility of the parental fish clones. The mechanisms determining the host resistance therefore did not associate with specific host immunity, but rather with innate or intrinsic factors. One cell line was resistant to rhabdovirus infection due to the combination of an early interferon IFN induction--that was not observed in the susceptible cells--and of yet unknown factors that hamper the first steps of the viral cycle. The implication of IFN was well consistent with the wide range of resistance of this genetic background to VSHV and IHNV, to the birnavirus IPNV and the orthomyxovirus ISAV. Another cell line was even more refractory to the VHSV infection through different antiviral mechanisms. This collection of clonal fish and isogenic cell lines provides an interesting model to analyze the relative contribution of antiviral pathways to the resistance to different viruses.     

Investigation of gamma-irradiated vegetable seeds with high-resolution solid-state 13C NMR

13C solid-state NMR was used to investigate the effects of gamma radiation on vegetable seeds, Pisum sativum and Latuca sativa, at absorbed doses that inhibit their germination. By combining single-pulse excitation and cross-polarization experiments under magic angle spinning, both liquid and solid domains of seeds can be characterized. We showed that the liquid domains, mostly made of triacylglycerols (TAG), of vegetable seeds are not sensitive to radiation. The main structural changes have been observed in the embryonic axes of seeds when the seeds are water-imbibed before irradiation. These results rule out a starting hypothesis concerning the potential role of TAG contained in oil bodies as a potential source of aldehydes that could further react with DNA moiety.     

Apurinic endonucleases from Saccharomyces cerevisiae.

Three endonuclease activities have been partially purified from Saccharomyces cerevisiae on the basis of their activity against x-irradiated closed-circular supercoiled bacteriophage PM2 DNA. These endonucleases also nick apurinic DNA and two out of the three activities incise DNA UV-irradiated with high doses. The endonuclease activities have also been distinguished on the basis of their magnesium requirement and sensitivity to EDTA.     

Microscopic structure of heterogeneous lipid-based formulations revealed by 13C high-resolution solid-state and 1H PFG NMR methods

Lipid-based formulations such as lip glosses that are very alike on the base of their components may have significant differences in their expected macroscopic properties as cosmetics. To differentiate such formulations, high-resolution ¹³C NMR was performed under magic angle spinning to investigate the properties at both molecular and microscopic levels. Temperature studies were carried out and no polymorphism in the solid domains could be evidenced after the thermal treatment performed for obtaining the commercial lip glosses. ¹³C NMR spectra also showed that some waxes remain partially solubilized in the oils of formulations. The microscopic structure of the wax-oil liquid domains was worked out on the basis of restricted diffusion properties obtained with proton pulsed-field gradient NMR. Changing a single wax component, in two identical formulations, yields significant morphological differences. In the first one the liquid phase appears as a continuum whereas in the second one, the liquid phase is fractionated into micrometric droplets.     

Association between Labeobarbus spp. (Teleostei: Cyprinidae) and environmental variables in the Luhoho basin (Eastern Congo River basin; DRC)

The African cyprinid genus Labeobarbus is characterized by a high polymorphism in mouth morphology. The association between four species of this genus (two chiselmouths, one rubberlip with a well-developed fleshy mental lobe on the lower jaw, i.e., a fleshy appendage on the chin, and one usually with a poorly developed one) and 26 environmental variables was investigated in four affluents of the Luhoho River in the Albertine Highlands of the Upper Congo basin. A combination of univariate and multivariate analyses suggested that differences exist in habitat composition at localities where different Labeobarbus species were reported, and within different mouth phenotypes. The association of L. longidorsalis with the presence of cobbles and pebbles and of L. brauni with the presence of boulders suggests that the occurrence of chiselmouths phenotype is associated with stony habitats, whereas phenotypes with a mental lobe, i.e., Labeobarbus longifilis and L. paucisquamatus, mostly occupy habitats without stones. Differences in the distribution between these two species appear to be linked to physico-chemical parameters such as electrical conductivity and water temperature rather than substrate type. The findings of this study are relevant for developing guidelines that aim effective local preservation and conservation of these Labeobarbus species.     

Is the simple auger coring method reliable for below-ground standing biomass estimation in Eucalyptus forest plantations?

Background and Aims

Despite their importance for plant production, estimations of below-ground biomass and its distribution in the soil are still difficult and time consuming, and no single reliable methodology is available for different root types. To identify the best method for root biomass estimations, four different methods, with labour requirements, were tested at the same location.

Methods

The four methods, applied in a 6-year-old Eucalyptus plantation in Congo, were based on different soil sampling volumes: auger (8 cm in diameter), monolith (25 × 25 cm quadrate), half Voronoi trench (1·5 m³) and a full Voronoi trench (3 m³), chosen as the reference method.

Key Results

With the reference method (0–1m deep), fine-root biomass (FRB, diameter <2 mm) was estimated at 1·8 t ha⁻¹, medium-root biomass (MRB diameter 2–10 mm) at 2·0 t ha⁻¹, coarse-root biomass (CRB, diameter >10 mm) at 5·6 t ha⁻¹ and stump biomass at 6·8 t ha⁻¹. Total below-ground biomass was estimated at 16·2 t ha⁻¹ (root : shoot ratio equal to 0·23) for this 800 tree ha⁻¹ eucalypt plantation density. The density of FRB was very high (0·56 t ha⁻¹) in the top soil horizon (0–3 cm layer) and decreased greatly (0·3 t ha⁻¹) with depth (50–100 cm). Without labour requirement considerations, no significant differences were found between the four methods for FRB and MRB; however, CRB was better estimated by the half and full Voronoi trenches. When labour requirements were considered, the most effective method was auger coring for FRB, whereas the half and full Voronoi trenches were the most appropriate methods for MRB and CRB, respectively.

Conclusions

As CRB combined with stumps amounted to 78 % of total below-ground biomass, a full Voronoi trench is strongly recommended when estimating total standing root biomass. Conversely, for FRB estimation, auger coring is recommended with a design pattern accounting for the spatial variability of fine-root distribution.     

Ketopantoate reductase activity is only encoded by ilvC in Corynebacterium glutamicum

Ketopantoate reductase catalyzes the second step of the pantothenate pathway after ketoisovalerate, common intermediate in valine, leucine and pantothenate biosynthesis. We show here that the Corynebacterium glutamicum ilvC gene is able to complement a ketopantoate reductase deficient Escherichia coli mutant. Thus ilvC, encoding acetohydroxyacid isomeroreductase, involved in the common pathway for branched-chained amino acids, also exhibits ketopantoate reductase activity. Enzymatic activity was confirmed by biochemical analysis in C. glutamicum. Furthermore, inactivation of ilvC in C. glutamicum leads to auxotrophy for pantothenate, indicating that ilvC is the only ketopantoate reductase- encoding gene in C. glutamicum.