Biocompatible wound dressings based on chemically degradable triblock copolymer hydrogels

The synthesis of a series of thermo-responsive ABA triblock copolymers in which the outer A blocks comprise poly(2-hydroxypropyl methacrylate) and the central B block is poly(2-(methacryloyloxy)ethyl phosphorylcholine) is achieved using atom transfer radical polymerization. These novel triblock copolymers form thermo-reversible physical gels with critical gelation temperatures and mechanical properties that are highly dependent on the copolymer composition and concentration. TEM studies on dried dilute copolymer solutions indicate the presence of colloidal aggregates, which is consistent with micellar gel structures. This hypothesis is consistent with the observation that incorporating a central disulfide bond within the B block leads to thermo-responsive gels that can be efficiently degraded using mild reductants such as dithiothreitol (DTT) over time scales of minutes at 37 degrees C. Moreover, the rate of gel dissolution increases at higher DTT/disulfide molar ratios. Finally, these copolymer gels are shown to be highly biocompatible. Only a modest reduction in proliferation was observed for monolayers of primary human dermal fibroblasts, with no evidence for cytotoxicity. Moreover, when placed directly on 3D tissue-engineered skin, these gels had no significant effect on cell viability. Thus, we suggest that these thermo-responsive biodegradable copolymer gels may have potential applications as wound dressings.     

Counter-Current Attrition Process (CCAP) to Remove Metals,Pentachlorophenol (PCP), Dioxins and Furans (PCDDF) from the 1-4-mm Fraction of Contaminated Soil

The objective of this study was to evaluate the potential of a counter-current attrition process (CCAP) over 15 cycles for removing metals, pentachlorophenol (PCP) and polychlorinated dibenzo-p-dioxins and -furans (PCDDF) from contaminated soil. The CCAP, applied to the 1–4-mm fraction of a contaminated soil, included five attrition steps (pulp density (PD) = 40% (w w^?1), surfactant [BW] = 2% (w w^?1), t = 20 min, T = 20°C) followed by one rinsing step. The water emerging from the first attrition step was treated using flocculation in the presence of 0.04 g CMX 123 (commercial flocculent) L^?1 before being reintroduced into the CCAP. The CCAP including the treatment of attrition wastewater (ATW) by flocculation achieved a removal of 44 ± 5% As, 26 ± 6% Cr, 24 ± 5% Cu, 49 ± 4% PCP and 45 ± 3% PCDDF. Moreover, the CCAP enabled a significant reduction (78%) in the amount of water required (around 14.5 m³ of water per ton of the 1–4-mm soil fraction). The high removal yields obtained after 15 attrition cycles of the CCAP for PCP and PCDDF and the significant reduction of water consumption confirm that this CCAP can be considered for industrial applications.     

Palmitic acid conjugation enhances potency of tricyclo-DNA splice switching oligonucleotides

Tricyclo-DNA (tcDNA) is a conformationally constrained oligonucleotide analog that has demonstrated great therapeutic potential as antisense oligonucleotide (ASO) for several diseases. Like most ASOs in clinical development, tcDNA were modified with phosphorothioate (PS) backbone for therapeutic purposes in order to improve their biodistribution by enhancing association with plasma and cell protein. Despite the advantageous protein binding properties, systemic delivery of PS-ASO remains limited and PS modifications can result in dose limiting toxicities in the clinic. Improving extra-hepatic delivery of ASO is highly desirable for the treatment of a variety of diseases including neuromuscular disorders such as Duchenne muscular dystrophy. We hypothesized that conjugation of palmitic acid to tcDNA could facilitate the delivery of the ASO from the bloodstream to the interstitium of the muscle tissues. We demonstrate here that palmitic acid conjugation enhances the potency of tcDNA-ASO in skeletal and cardiac muscles, leading to functional improvement in dystrophic mice with significantly reduced dose of administered ASO. Interestingly, palmitic acid-conjugated tcDNA with a full phosphodiester backbone proved effective with a particularly encouraging safety profile, offering new perspectives for the clinical development of PS-free tcDNA-ASO for neuromuscular diseases.     

Daily and seasonal activity patterns of the dorcas gazelle,scimitar-horned oryx,north-African ostrich and canids in an arid habitat

North Africa's megafauna has developed behavioural adaptations to reduce energetic and fitness costs under harsh arid land conditions. Animal behaviour and activity patterns are difficult to study in the wild, but remote camera traps provide a solution to collecting data without the presence of a researcher influencing outcomes. Here, we report results from a study comprising over 20,382 camera-trap days during a 34-month period in Dghoumes National Park, Tunisia. We aimed to evaluate temporal activity patterns and their overlap and explore opportunities for niche partitioning. Our focal species were the reintroduced scimitar-horned oryx, north-African ostrich, dorcas gazelles and extant regional top-order predators, African wolf and red fox. We found differences in activity patterns between seasons across the focal species, with the most noticeable change being an increase in dawn activity from 1% to 33% between winter and summer for the red fox. Consequently, higher summer temperatures limit opportunities for temporal niche partitioning and push focal species towards dawn-time activity peaks resulting in higher intra-guild overlap values at dawn. Arid antelopes have physiological adaptations that enable them to better exploit ecological resources in hotter time periods than the carnivores, and this reduces inter-guild overlap during summer days.     

Cytisus villosus from Northeastern Algeria is nodulated by genetically diverse Bradyrhizobium strains

Fifty-one rhizobial strains isolated from root nodules of Cytisus villosus growing in Northeastern Algeria were characterized by genomic and phenotypic analyses. Isolates were grouped into sixteen different patterns by PCR-RAPD. The phylogenetic status of one representative isolate from each pattern was examined by multilocus sequence analyses of four housekeeping genes (16S rRNA, glnII, recA, and atpD) and one symbiotic gene (nodC). Analysis of 16S rRNA gene sequences showed that all the isolates belonged to the genus Bradyrhizobium. Phylogenetic analyses based on individual or concatenated genes glnII, recA, and atpD indicated that strains cluster in three distinct groups. Ten out of the sixteen strains grouped together with Bradyrhizobium japonicum, while a second group of four clustered with Bradyrhizobium canariense. The third group, represented by isolates CTS8 and CTS57, differed significantly from all other bradyrhizobia known to nodulate members of the Genisteae tribe. In contrast with core genes, sequences of the nodC symbiotic gene from all the examined strains form a homogeneous group within the genistearum symbiovar of Bradyrhizobium. All strains tested nodulated Lupinus angustifolius, Lupinus luteus, and Spartium junceum but not Glycine max. From these results, it is concluded that C. villosus CTS8 and CTS57 strains represent a new lineage within the Bradyrhizobium genus.     

GluN2D‐containing NMDA receptors inhibit neurotransmission in the mouse striatum through a cholinergic mechanism: implication for Parkinson's disease

The GluN2 subunits that compose NMDA receptors (NMDARs) determine functional and pharmacological properties of the receptor. In the striatum, functions and potential dysfunctions of NMDARs attributed to specific GluN2 subunits have not been clearly elucidated, although NMDARs play critical roles in the interactions between glutamate and dopamine. Through the use of amperometry and field potential recordings in mouse brain slices, we found that NMDARs that contain the GluN2D subunit contribute to NMDA‐induced inhibition of evoked dopamine release and of glutamatergic neurotransmission in the striatum of control mice. Inhibition is likely mediated through increased firing in cholinergic interneurons, which were shown to express GluN2D. Indeed, NMDA‐induced inhibition of both dopamine release and glutamatergic neurotransmission is reduced in the presence of muscarinic receptor antagonists and is mimicked by a muscarinic receptor agonist. We have also examined whether this function of GluN2D‐containing NMDARs is altered in a mouse model of Parkinson's disease. We found that the inhibitory role of GluN2D‐containing NMDARs on glutamatergic neurotransmission is impaired in the 6‐hydroxydopamine lesioned striatum. These results identify a role for GluN2D‐containing NMDARs and adaptive changes in experimental Parkinsonism. GluN2D might constitute an attractive target for the development of novel pharmacological tools for therapeutic intervention in Parkinson's disease.

     

Time measurement in the photoperiodic induction of sexual rest in the terrestrial isopod Armadillidium vulgare (Latreille)

The photoperiodic control of sexual rest in Armadillidium vulgare was investigated using various experimental protocols. When reared in conditions of a Nanda-Hamner (i.e. resonance) protocol from their first parturial moult to their post experimental moult, females showed a weak resonance effect in sexual rest incidence. The transfer from a long day cycle to a symmetrical skeleton photoperiod--consisting of two equal light pulses per 24 h of continuous darkness--revealed the involvement of a circadian oscillatory system in the photoperiodic clock of this species. The data, obtained in the whole experiments, suggested that both oscillator and hourglass features are involved in the photoperiodic response controlling the sexual rest in Armadillidium vulgare. Moreover, when non-24-h light-dark cycles (with a long photophase) were applied, a mechanism responsible of arrest of reproduction also implied a photoperiodic counter which accumulated and added up the photoperiodic information within a sensitive period during post parturial intermoult.     

Composition of Bacterial Communities Associated with Natural and Laboratory Populations of Asobara tabida Infected with Wolbachia

Asobara tabida wasps are fly endoparasitoids that naturally harbor three Wolbachia strains, which induce cytoplasmic incompatibility and control oogenesis. To investigate whether other bacteria play a role in wasp biology, we surveyed the bacterial communities of wild A. tabida populations originating from different regions of France and of laboratory colonies using PCR-denaturing gradient gel electrophoresis and culture methods. Proteobacteria and Firmicutes were found to be the main phyla represented in these populations. Among these were several cultured and uncultured representatives of the genera Acetobacter, Acidomonas, Bacillus, Brevibacillus, Duganella, Herbaspirillum, Pseudomonas, Staphylococcus, and Streptococcus. In addition to Wolbachia, wild individuals harbored Rickettsia, which tended to be lost when insects were reared in the laboratory. The antibiotic treatment used to generate wasp sublines singly infected with Wolbachia also affected the overall bacterial composition, with most fingerprint sequences being characteristic of the family Enterobacteriaceae. We also screened for potentially heritable endosymbionts by PCR and fluorescence in situ hybridization in stable laboratory lines, with only Wolbachia being consistently found in wasp ovaries.Bacteria associated with insects play a crucial role in host development, survival, and reproduction (13). Many insects harbor bacterial endosymbionts, which establish close relationships, like the mutualistic interaction between aphids and their primary endosymbiont of the genus Buchnera; the bacterium uses the host as a habitat to which it supplies essential amino acids, facilitating insect growth when the diet of plant phloem sap is insufficient (5, 23). Aphids host many other nonessential bacteria as secondary or facultative symbionts. However, aphids with secondary symbionts can gain a fitness advantage in terms of diet, regimen plant host range, heat tolerance, or resistance to pathogens and parasitoids (reviewed in references 45 and 48). Multiple infections are costly to hosts and are perhaps maintained because of the benefits they confer. Recently, Wolbachia has been shown to protect the host Drosophila melanogaster from viral damage (37). However, investigating the evolutionary significance of interspecific symbioses in bacterial communities in invertebrates is challenging in that the majority of bacteria are not yet cultivable outside host cells.Here we analyzed the main bacterial populations of Asobara tabida (Hymenoptera: Braconidae), endoparasitoids of Drosophila species and related genera (14). Usually, members of A. tabida are naturally multiply infected with bacteria of the genus Wolbachia, obligate intracellular Alphaproteobacteria of the order Rickettsiales (2, 25, 51), found in association with numerous arthropods, mainly insects, and certain nematodes, where they are mostly vertically transmitted from mother to progeny (74). The interaction between Wolbachia spp. and their hosts is very complex and ranges from parasitism to mutualism. In filarial nematodes, Wolbachia organisms are required in the host''s biology (4), but Wolbachia spp. are mostly parasites that affect arthropod reproduction, such as by inducing parthenogenesis in some parasitoid wasps (63), feminizing genetic males in isopods (9), and inducing male killing and cytoplasmic incompatibility in many insects (39, 64). The wasp A. tabida harbors three Wolbachia strains; strains wAtab1 and wAtab2 induce cytoplasmic incompatibility, whereas wAtab3 is necessary for the completion of oogenesis (19, 20, 73). The involvement of Wolbachia strains in wasp reproduction was discovered when wasps were treated with antibiotics to generate lines harboring subsets of Wolbachia or aposymbiotic lines (19, 21). Only oogenesis was affected by curing Wolbachia wAtab3; other traits, such as insect size, weight, locomotion, and behavior, were unchanged (19). While antibiotic treatment has been used to determine biological roles of symbionts in this way, their effect on the overall composition of bacterial populations has not been investigated.To investigate the potential role of bacterial endosymbionts in the biology of A. tabida, we studied the bacterial communities in insect populations originating from different regions of France using culture and nonculture methods and fluorescence in situ hybridization (FISH). We also examined whether antibiotherapy to generate lines with a subset of Wolbachia strains altered the composition or density of the bacterial communities.     

Phenotypic and fine genetic characterization of the D locus controlling fruit acidity in peach

Background  

Acidity is an essential component of the organoleptic quality of fleshy fruits. However, in these fruits, the physiological and molecular mechanisms that control fruit acidity remain unclear. In peach the D locus controls fruit acidity; low-acidity is determined by the dominant allele. Using a peach progeny of 208 F₂ trees, the D locus was mapped to the proximal end of linkage group 5 and co-localized with major QTLs involved in the control of fruit pH, titratable acidity and organic acid concentration and small QTLs for sugar concentration. To investigate the molecular basis of fruit acidity in peach we initiated the map-based cloning of the D locus.     

Ancient local evolution of African mtDNA haplogroups in Tunisian Berber populations

Our objective is to highlight the age of sub-Saharan gene flows in North Africa and particularly in Tunisia. Therefore we analyzed in a broad phylogeographic context sub-Saharan mtDNA haplogroups of Tunisian Berber populations considered representative of ancient settlement. More than 2,000 sequences were collected from the literature, and networks were constructed. The results show that the most ancient haplogroup is L3*, which would have been introduced to North Africa from eastern sub-Saharan populations around 20,000 years ago. Our results also point to a less ancient western sub-Saharan gene flow to Tunisia, including haplogroups L2a and L3b. This conclusion points to an ancient African gene flow to Tunisia before 20,000 BP. These findings parallel the more recent findings of both archaeology and linguistics on the prehistory of Africa. The present work suggests that sub-Saharan contributions to North Africa have experienced several complex population processes after the occupation of the region by anatomically modern humans. Our results reveal that Berber speakers have a foundational biogeographic root in Africa and that deep African lineages have continued to evolve in supra-Saharan Africa.