Oscheius tipulae, a widespread hermaphroditic soil nematode, displays a higher genetic diversity and geographical structure than Caenorhabditis elegans

The nematode Oscheius tipulae belongs to the same family (Rhabditidae) as the model species Caenorhabditis elegans . Both species reproduce through self-fertilizing hermaphrodites and facultative males. Recent studies have shown that the self-fertile C. elegans and C. briggsae displayed a 20-fold lower genetic diversity than the male–female species C. remanei . Several explanations have been put forward to account for this difference, including their mode of reproduction and dynamic population structure. Here, we present the results of extensive worldwide sampling of O. tipulae , which we previously used as a laboratory organism for developmental genetics. We found that O. tipulae is much more widespread and common in soil throughout the world than Caenorhabditis species. We analysed 63 O. tipulae isolates from several continents using amplified fragment length polymorphism (AFLP). We found that O. tipulae harbours a 5-fold higher genetic diversity than C. elegans and C. briggsae . As in C. elegans , a high proportion of this diversity was found locally. Yet, we detected significant geographical differentiation, both at the worldwide scale with a latitudinal structure and between three localities in France. In summary, O. tipulae exhibited significantly higher levels of genetic diversity and large-scale geographical structure than C. elegans , despite their shared mode of reproduction. This species difference in genetic diversity may be explained by a number of other differences, such as population size, distribution, migration and dynamics. Due to its widespread occurrence and relatively high genetic diversity, O. tipulae may be a promising study species for evolutionary studies.     

Characterization of catalase and superoxide dismutase in Staphylococcus carnosus 833 strain

AIMS: Staphylococcus carnosus, used as starter culture in fermented meat products, decreases the level of volatiles arising from lipid oxidation. To analyse its antioxidant capacities, catalase and superoxide dismutase (SOD) were characterized. METHODS AND RESULTS: Catalase and SOD activities were measured with spectrophotometric methods and visualized on non-denaturing polyacrylamide gels. The corresponding sod gene was identified by PCR. Southern hybridizations and enzymatic analyses showed that there was a single catalase and a single SOD in Staph. carnosus 833 strain. The gene encoding the Staph. carnosus SOD was found to encode a protein closely related to SOD requiring manganese. Catalase and SOD levels increased in mid-log phase. Only catalase was induced by oxygen, nitrate or nitrite while glucose induced neither enzyme. Metal ion limitation increased catalase and decreased SOD activities. CONCLUSION: Staph. carnosus synthesizes both enzymes in conditions encountered in sausage manufacturing. These results could explain the antioxidant properties of Staph. carnosus starter culture. SIGNIFICANCE AND IMPACT OF THE STUDY: The knowledge of the antioxidant properties of Staphylococci will allow a more rational use of these starters in meat fermented products.     

Application of the thiocarbohydrazide method for vicinal glycol group detection to the study of gastric mucosa endocrine cells

Summary The thiocarbohydrazide-silver proteinate (TCH-SP) method was applied to the study of cat, rabbit and mouse gastric mucosa endocrine cells. After 24-h treatment with thiocarbohydrazide (TCH), glycogen was seen in the hyaloplasm of X, D, P, A and O cells but not in EC, EC-like or D₁ cells. With flotation times as short as 30 to 40 min glycogen was readily detected in X cells. Secretory granules of EC cells were constantly stained, while those of D₁ cells failed to react. In most experiments granules of X, A and O cells showed peripheral staining, while in others staining of variable intensity affected the entire granular cross-section in X, D and P cells. With 72-h exposure to TCH, EC and EC-like cells showed particles resembling glycogen, even staining or only peripheral staining of certain EC cell granules. From the results of this and previous studies, EC cell staining is believed to be due wholly or partly, according to exposure times, to the action of silver proteinate, while that of certain non-EC cells is probably a specific indicator of complexed carbohydrates.     

Nucleotide sequence of bup, an upstream gene in the bmi-1 proviral insertion locus.

The ability of Moloney murine leukemia virus to accelerate lymphomagenesis in E mu-myc transgenic mice is frequently associated with proviral integration within a locus denoted bmi-1. This locus contains not only the bmi-1 gene implicated as a collaborator with myc in lymphomagenesis but also just upstream an unknown gene denoted bup. The nucleotide sequence reported here for bup cDNA and flanking genomic sequences reveals that this widely expressed gene comprises at least 7 exons and potentially encodes a polypeptide of 195 amino acid residues. Computer searches with this polypeptide sequence revealed no close homolog in the databases, nor any conserved motifs, and it is unrelated to the product of the mel-13 gene, which lies just upstream from the bmi-1 homolog mel-18.     

Age-Related Changes in Pre- and Postsynaptic Partners of the Cholinergic C-Boutons in Wild-Type and SOD1G93A Lumbar Motoneurons

Large cholinergic synaptic terminals known as C-boutons densely innervate the soma and proximal dendrites of motoneurons that are prone to neurodegeneration in amyotrophic lateral sclerosis (ALS). Studies using the Cu/Zn-superoxide dismutase (SOD1) mouse model of ALS have generated conflicting data regarding C-bouton alterations exhibited during ALS pathogenesis. In the present work, a longitudinal study combining immunohistochemistry, biochemical approaches and extra- and intra-cellular electrophysiological recordings revealed that the whole spinal cholinergic system is modified in the SOD1 mouse model of ALS compared to wild type (WT) mice as early as the second postnatal week. In WT motoneurons, both C-bouton terminals and associated M2 postsynaptic receptors presented a complex age-related dynamic that appeared completely disrupted in SOD1 motoneurons. Indeed, parallel to C-bouton morphological alterations, analysis of confocal images revealed a clustering process of M2 receptors during WT motoneuron development and maturation that was absent in SOD1 motoneurons. Our data demonstrated for the first time that the lamina X cholinergic interneurons, the neuronal source of C-boutons, are over-abundant in high lumbar segments in SOD1 mice and are subject to neurodegeneration in the SOD1 animal model. Finally, we showed that early C-bouton system alterations have no physiological impact on the cholinergic neuromodulation of newborn motoneurons. Altogether, these data suggest a complete reconfiguration of the spinal cholinergic system in SOD1 spinal networks that could be part of the compensatory mechanisms established during spinal development.     

A Physiological and Behavioral Mechanism for Leaf Herbivore-Induced Systemic Root Resistance

Indirect plant-mediated interactions between herbivores are important drivers of community composition in terrestrial ecosystems. Among the most striking examples are the strong indirect interactions between spatially separated leaf- and root-feeding insects sharing a host plant. Although leaf feeders generally reduce the performance of root herbivores, little is known about the underlying systemic changes in root physiology and the associated behavioral responses of the root feeders. We investigated the consequences of maize (Zea mays) leaf infestation by Spodoptera littoralis caterpillars for the root-feeding larvae of the beetle Diabrotica virgifera virgifera, a major pest of maize. D. virgifera strongly avoided leaf-infested plants by recognizing systemic changes in soluble root components. The avoidance response occurred within 12 h and was induced by real and mimicked herbivory, but not wounding alone. Roots of leaf-infested plants showed altered patterns in soluble free and soluble conjugated phenolic acids. Biochemical inhibition and genetic manipulation of phenolic acid biosynthesis led to a complete disappearance of the avoidance response of D. virgifera. Furthermore, bioactivity-guided fractionation revealed a direct link between the avoidance response of D. virgifera and changes in soluble conjugated phenolic acids in the roots of leaf-attacked plants. Our study provides a physiological mechanism for a behavioral pattern that explains the negative effect of leaf attack on a root-feeding insect. Furthermore, it opens up the possibility to control D. virgifera in the field by genetically mimicking leaf herbivore-induced changes in root phenylpropanoid patterns.Insect herbivores constantly compete for plants as a primary terrestrial source of organic carbon and nitrogen (Denno et al., 1995). Consequently, resource competition is thought to be a major determinant of the distribution and abundance of insects in natural and agricultural systems (Begon et al., 2006). Recent evidence suggests, however, that in many cases, insect herbivore competition may not follow the traditional theoretical assumptions of direct interference and/or resource exploitation, but may be determined by indirect plant-mediated effects (Kaplan and Denno, 2007; Poelman et al., 2008). Among the most striking examples of indirect plant-mediated interactions is the interplay between root- and leaf-feeding insects (Blossey and Hunt-Joshi, 2003). Despite their nonoverlapping feeding niches, leaf and root herbivores determine each other’s performance through shared host plants (Bezemer and van Dam, 2005). Although root feeders can have positive or negative effects on leaf feeders (van Dam and Heil, 2011), the effect of leaf herbivores on root consumers is predominantly negative (Johnson et al., 2012; Huang et al., 2014).Despite the increasing number of examples demonstrating negative effects of leaf attack on root herbivores (Tindall and Stout, 2001; Blossey and Hunt-Joshi, 2003; Soler et al., 2007; Gill et al., 2011), the mechanisms underlying this form of systemic induced resistance remain poorly understood (Erb et al., 2008; Rasmann and Agrawal, 2008). Pieris brassicae, for instance, was found to increase glucosinolate levels in the roots, which correlated with a reduced survival of the root feeder Delia radicum (Soler et al., 2007). Understanding why root feeders perform worse on leaf-infested plants would allow for more detailed investigations regarding the adaptive and evolutionary context of the phenomenon, and may allow for its exploitation in agriculture (for instance, by triggering root resistance through targeted leaf treatments).A promising system to study the mechanisms and agroecological consequences of plant-mediated interactions between herbivores is maize (Zea mays) and its associated pests. In the field, maize is attacked by a suite of herbivores, including leaf feeders, stem borers, and root feeders. The highly specialized root-feeding larvae of the western corn rootworm Diabrotica virgifera virgifera cause significant plant damage and yield loss in the United States and Eastern Europe. Earlier studies demonstrated that D. virgifera attack increases leaf resistance against Spodoptera spp. by triggering drought stress responses (Erb et al., 2009, 2011b). In the opposite direction, leaf feeding by Spodoptera spp. caterpillars reduces D. virgifera growth and development in a sequence-specific manner in the laboratory and the field (Erb et al., 2011c; Gill et al., 2011). D. virgifera was subsequently demonstrated to avoid leaf-infested plants by detecting and responding to a reduction in root ethylene emissions (Robert et al., 2012). However, it remains unclear whether nonvolatile chemical changes in the roots of leaf-infested maize plants affect D. virgifera foraging and performance. In this study, we explored the hypothesis that leaf infestation by Spodoptera spp. caterpillars triggers a short-range avoidance response in D. virgifera. Through a combination of bioactivity-guided fractionation of root extracts and biochemical and molecular manipulation, we show that systemic changes in soluble phenylpropanoid derivatives trigger a strong avoidance response in D. virgifera. We furthermore demonstrate that this avoidance response is mediated by systemic internal signals and is triggered specifically by herbivory, suggesting that D. virgifera actively and specifically recognizes and avoids leaf-infested plants.     

Derivation of human embryonic stem cells at the Center of Regenerative Medicine in Barcelona

We report here the legislative issues related to embryo research and human embryonic stem cell (hESC) research in Spain and the derivation of nine hESC lines at the Center of Regenerative Medicine in Barcelona. You can find the information for obtaining our lines for research purposes at blc@cmrb.eu.