Alien chromosome transmission and somatic elimination in monosomic addition lines of Gossypium australe F. Muell in G. hirsutum L.

The efficiency of using monosomic alien addition lines (MAALs) to introgress agronomical traits of interest carried by wild diploid Gossypium species into the main cultivated cotton species G. hirsutum depends on the opportunities of confronting the alien chromosome with the recipient background genome at each generation and on the occurrence of translocations and homoeologous recombinations. The selfed-progeny of five MAALs of G. australe in G. hirsutum was screened with SSR markers to determine the transmission frequency of the alien chromosome and monitor its integrity. Three MAALs revealed a transmission frequency significantly lower than the expected ratio and one MAAL presented an exclusive transmission of the additional chromosome. In these four MAAL the alien chromosome was transmitted almost unaltered. With the fifth MAAL the alien chromosome was normally transmitted but was altered in half of the plants carrying it. In one MAAL, normally carrying brown fiber, the emergence of some plants carrying white and brown fiber revealed the somatic elimination of the additional chromosome. The loss of this chromosome seems to be triggered by its deletion.     

Porcine reproductive and respiratory syndrome virus: antigenic and molecular diversity of British isolates and implications for diagnosis

Porcine reproductive and respiratory syndrome (PRRS) is an endemic disease of pigs, caused by PRRS virus, a member of the Arteriviridae family. First seen in Britain in 1991, the disease continues to be a significant economic and welfare problem for pig producers. To date, only PRRSV genotype 1 has been found in Britain. At the genetic level, a considerable increase has been reported in the diversity of PRRS viruses isolated in Britain between 2003 and 2007, versus the early 1990 s. In this study, the diversity has been shown to extend to the antigenic level too, with potential consequences for diagnostic methods. Antigenic diversity was assessed using a panel of twelve monoclonal antibodies, only one of which reacted with all isolates tested. Nine diverse viruses were compared as potential antigens in immunoperoxidase monolayer assays, where each one produced quite different results for a common panel of sera. As a single virus is used in each diagnostic assay, results must therefore be interpreted cautiously. For a real-time RT-PCR assay, published oligonucleotide primer and probe sequences were evaluated against available genetic sequences of British and European viruses, and were re-designed where considerable mismatches were found. The multiplex assay incorporating these modified primers to detect genotype 1 and 2 PRRS viruses was then validated for use with diagnostic sera and tissues. As the increasing degree of diversity exhibited by British strains is mirrored in other countries, PRRSV will continue to provide an ongoing challenge to diagnosis at a global, as well as national level.     

Prognostic significance of morphological subtypes in canine malignant lymphomas during chemotherapy

The aim of this study was to determine the response of different morphological subtypes of canine lymphoma to a standardized therapeutic protocol. Diagnosis of lymphoma was based on cytohistological analysis and immunophenotyping with antibodies against CD3 and CD79a of an enlarged lymph node or an extranodal mass. Fifty-seven cases were classified according to the updated Kiel classification adapted to the canine species, into 24 B-cell lymphomas (20 centroblastic polymorphic and four Burkitt-type subtypes), and 33 T-cell lymphomas (10 pleomorphic mixed, 10 lymphoblastic, eight unclassifiable high grade plasmacytoid, and five small clear-cell subtypes). All dogs were clinically staged at diagnosis. The protocol used l-asparaginase, vincristine, cyclophosphamide, doxorubicin, and prednisone. First remission duration and overall survival time were evaluated. Although the T-cell phenotype was associated, on the whole, with a poor prognosis, as previously reported in veterinary and human medicine, the study showed significant prognostic differences between the B- and the T-cell subtypes of canine lymphoma and suggests that clinico-morphological characterization of the disease is justified in dogs, as in humans.     

Comparative analysis of Andiodrilus pachoensis casts in forests and pastures of South-Eastern Amazon (Brazil)

Soil ecosystem engineers produce biogenic structures (casts, mounds, galleries) that strongly affect soil processes. A comparative analysis of the physical characteristics of the casts produced by the earthworm Andiodrilus pachoensis was carried out in four pastures sowed with Brachiaria brizantha and four primary forests on the deforestation front of the Amazonian forest. In both systems, we recorded surface cast density and spatial patterns as well as surface cast physical properties. Cast and vegetation distributions were mapped within plots of sizes ranging from 25 to 50 m², and cast production was monitored during 2 months. Cast spatial distribution varied greatly among plots and across spatial scales ranging from regular at small spatial scales (0–20 cm) to clumped for larger distance ranges (>80 cm). Cast density was not significantly correlated with grass tuft density and their production was independent from the presence of grass tufts in pastures or litter quantity in forests. Although bulk soil properties (pH, C content, structural stability, etc) differed between pastures and forests, cast physical properties did not differ significantly among the studied ecosystem.     

Physiological role of the cellular prion protein

The prion protein (PrP) plays a key role in the pathogenesis of prion diseases. However, the normal function of the protein remains unclear. The cellular isoform (PrP(C)) is expressed most abundantly in the brain, but has also been detected in other non-neuronal tissues as diverse as lymphoid cells, lung, heart, kidney, gastrointestinal tract, muscle, and mammary glands. Cell biological studies of PrP contribute to our understanding of PrP(C) function. Like other membrane proteins, PrP(C) is post-translationally processed in the endoplasmic reticulum and Golgi on its way to the cell surface after synthesis. Cell surface PrP(C) constitutively cycles between the plasma membrane and early endosomes via a clathrin-dependent mechanism, a pathway consistent with a suggested role for PrP(C) in cellular trafficking of copper ions. Although PrP(-/-) mice have been reported to have only minor alterations in immune function, PrP(C) is up-regulated in T cell activation and may be expressed at higher levels by specialized classes of lymphocytes. Furthermore, antibody cross-linking of surface PrP(C) modulates T cell activation and leads to rearrangements of lipid raft constituents and increased phosphorylation of signaling proteins. These findings appear to indicate an important but, as yet, ill-defined role in T cell function. Recent work has suggested that PrP(C) is required for self-renewal of haematopoietic stem cells. PrP(C) is highly expressed in the central nervous system, and since this is the major site of prion pathology, most interest has focused on defining the role of PrP(C) in neurones. Although PrP(-/-) mice have a grossly normal neurological phenotype, even when neuronal PrP(C) is knocked out postnatally, they do have subtle abnormalities in synaptic transmission, hippocampal morphology, circadian rhythms, and cognition and seizure threshold. Other postulated neuronal roles for PrP(C) include copper-binding, as an anti- and conversely, pro-apoptotic protein, as a signaling molecule, and in supporting neuronal morphology and adhesion. The prion protein may also function as a metal binding protein such as copper, yielding cellular antioxidant capacity suggesting a role in the oxidative stress homeostasis. Finally, recent observations on the role of PrP(C) in long-term memory open a challenging field.     

Transiliac approach for exposure of lumbosacral intervertebral disk and foramen: technique description

Objective— To describe and evaluate a transiliac approach to the L7–S1 disk and intervertebral foramen in dogs.
Study Design— Cadaver study.
Animals— Fresh canine cadavers (n=10).
Methods— A craniolateral approach was made to each iliac wing of 10 fresh canine mixed breed cadavers. An 18 mm hole was drilled in a standardized position through the iliac wing. The musculature connected to the cranial aspects of the sacral wing was dissected and retracted cranially through this iliac window. Endoscopic exploration of the area was performed.
Results— The foramen and intervertebral disk were clearly observed in all specimens without iatrogenic injury of the L7 nerve branch. Access to the foramen was possible in 16 of 20 specimens without excision of the sacral wing; however, it was always partially excised to observe the intervertebral disk which lies more caudally and ventrally.
Conclusion— Transiliac approach to the lumbosacral joint allows direct exposure of the intervertebral disk and foramen through an iliac window. Endoscopic exploration provided good observation of the intervertebral disk and/or foramen.
Clinical Relevance— Transiliac approach could be used for lateral corpectomy and foraminotomy in dogs with degenerative lumbosacral stenosis caused by ventral or ventrolateral disk protrusion, foramen stenosis, or OCD of the L7–S1 joint. Clinical study will be necessary to evaluate the efficacy of this approach.     

Functional identification of phenazine biosynthesis genes in plant pathogenic bacteria Pseudomonas syringae pv. tomato and Xanthomonas oryzae pv. oryzae

Phenazines are secondary metabolites with broad spectrum antibiotic activity and thus show high potential in biological control of pathogens.In this study,we identified phenazine biosynthesis（phz）genes in two genome-completed plant pathogenic bacteria Pseudomonas syringae pv.tomato（Pst）DC3000 and Xanthomonas oryzae pv.oryzae（Xoo）PXO99^A.Unlike the phz genes in typical phenazine-producing pseudomonads,phz homologs in Pst DC3000 and Xoo PXO99^A consisted of phzC/D/E/F/G and phzC/E1/E2/F/G,respectively,and the both were not organized into an operon.Detection experiments demonstrated that phenazine-1-carboxylic acid（PCA）of Pst DC3000 accumulated to 13.4μg L^-1,while that of Xoo PXO99^A was almost undetectable.Moreover,Pst DC3000 was resistant to 1 mg mL^-1PCA,while Xoo PXO99^A was sensitive to50μg mL^-1PCA.Furthermore,mutation of phzF blocked the PCA production and significantly reduced the pathogenicity of Pst DC3000 in tomato,while the complementary strains restored these phenotypes.These results revealed that Pst DC3000 produces low level of and is resistant to phenazines and thus is unable to be biologically controlled by phenazines.Additionally,phz-mediated PCA production is required for full pathogenicity of Pst DC3000.To our knowledge,this is the first report of PCA production and its function in pathogenicity of a plant pathogenic P.syringae strain.     

Colonisation of native and exotic conifers by indigenous bark beetles (Coleoptera: Scolytinae) in France

Planting exotic conifers offers indigenous forest insects an opportunity to extend their host range and eventually to become significant pests. Knowing the ecological and evolutionary modalities driving the colonisation of exotic tree species by indigenous insects is thus of primary importance. We compared the bark beetle communities (Coleoptera: Curculionidae, Scolytinae) associated with both native and introduced conifers in France. The aim of our study was to estimate the influence of both host- and insect-related factors on the beetles’ likelihood to shift onto new hosts. We considered the influence of host origin (i.e. native vs. exotic), host tree species identity, tree bark thickness and tree taxonomic proximity, as well as insects’ host specificity. A field inventory using trap trees was carried out in two regions in France (Limousin and Jura) during two consecutive years (2006 and 2007) on three European native conifer species [Norway spruce (Picea abies); Scots pine (Pinus sylvestris) and European Silver-fir (Abies alba)] and five North American [Sitka spruce (Picea sitchensis); Eastern white pine (Pinus strobus); Grand fir (Abies grandis); Douglas fir (Pseudotsuga menziesii) and Western red cedar (Thuja plicata)]. A total of 18 indigenous and 2 exotic bark beetle species were collected. All exotic conifer species were colonised by indigenous bark beetle species and no significant difference was observed of the cumulated species richness of the latter between native and exotic tree species (13 vs. 14, P < 0.05). The ability of indigenous bark beetles to shift onto exotic conifers appeared to strongly depend on host species (significantly structuring bark beetle assemblages), the presence of phylogenetically related native conifer species and that of similar resources, in combination with insect host specificity. Host tree species status (native or exotic) also seemed to be involved, but its effect did not seem as essential as that of the previous factors. These findings are discussed in terms of adaptation, plasticity and practical aspects of forest management.