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.

     

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.     

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.     

Effect of long-term exposure of SH-SY5Y cells to morphine: a whole cell proteomic analysis

Background  

Opiate addiction reflects plastic changes that endurably alter synaptic transmission within relevant neuronal circuits. The biochemical mechanisms of these adaptations remain largely unknown and proteomics-based approaches could lead to a broad characterization of the molecular events underlying adaptations to chronic drug exposure.     

Differential compartmental processing and phosphorylation of pathogenic human tau and native mouse tau in the line 66 model of frontotemporal dementia

Synapse loss is associated with motor and cognitive decline in multiple neurodegenerative disorders, and the cellular redistribution of tau is related to synaptic impairment in tauopathies, such as Alzheimer''s disease and frontotemporal dementia. Here, we examined the cellular distribution of tau protein species in human tau overexpressing line 66 mice, a transgenic mouse model akin to genetic variants of frontotemporal dementia. Line 66 mice express intracellular tau aggregates in multiple brain regions and exhibit sensorimotor and motor learning deficiencies. Using a series of anti-tau antibodies, we observed, histologically, that nonphosphorylated transgenic human tau is enriched in synapses, whereas phosphorylated tau accumulates predominantly in cell bodies and axons. Subcellular fractionation confirmed that human tau is highly enriched in insoluble cytosolic and synaptosomal fractions, whereas endogenous mouse tau is virtually absent from synapses. Cytosolic tau was resistant to solubilization with urea and Triton X-100, indicating the formation of larger tau aggregates. By contrast, synaptic tau was partially soluble after Triton X-100 treatment and most likely represents aggregates of smaller size. MS corroborated that synaptosomal tau is nonphosphorylated. Tau enriched in the synapse of line 66 mice, therefore, appears to be in an oligomeric and nonphosphorylated state, and one that could have a direct impact on cognitive function.     

Helicobacter pylori Genotypes Associated with Gastric Histo-Pathological Damages in a Moroccan Population

H. pylori persistent infection induces chronic gastritis and is associated with peptic ulcer disease and gastric carcinoma development. The severity of these diseases is related to human’s genetic diversity, H. pylori genetic variability and environmental factors. To identify the prevalence of histo-pathological damages caused by H. pylori infection in Moroccan population, and to determine their association to H. pylori genotypes, a prospective study has been conducted during 3 years on patients attending the gastroenterology department of Hassan II University Hospital (CHU) of Fez, Morocco. A total of 801 Moroccan adults’ patients were recruited; H. pylori was diagnosed and genotyped by PCR in biopsy specimens and histological exam was performed. We found a high rate of glandular atrophy. Chronic inflammation, neutrophil activity and glandular atrophy showed statistically significant association with H. pylori infection. However, intestinal metaplasia was inversely associated to this infection and no association was observed with gastric cancer cases. A statistically significant association was found between intestinal metaplasia and vacAs1 and vac Am1 genotypes in patients aged 50 years and more but not in younger. This last genotype is also associated to gastric cancer. In this study, gastric cancer showed no significant association with H. pylori. Further studies are warranted to determine the role of other etiological agents such as Epstein-Barr virus, human papillomavirus and possibly environmental and dietetic factors in the occurrence of this pathology.     

Automatic image segmentation of nuclear stained breast tissue sections using color active contour model and an improved watershed method

Automatic image segmentation of immunohistologically stained breast tissue sections helps pathologists to discover the cancer disease earlier. The detection of the real number of cancer nuclei in the image is a very tedious and time consuming task. Segmentation of cancer nuclei, especially touching nuclei, presents many difficulties to separate them by traditional segmentation algorithms. This paper presents a new automatic scheme to perform both classification of breast stained nuclei and segmentation of touching nuclei in order to get the total number of cancer nuclei in each class. Firstly, a modified geometric active contour model is used for multiple contour detection of positive and negative nuclear staining in the microscopic image. Secondly, a touching nuclei method based on watershed algorithm and concave vertex graph is proposed to perform accurate quantification of the different stains. Finally, benign nuclei are identified by their morphological features and they are removed automatically from the segmented image for positive cancer nuclei assessment. The proposed classification and segmentation schemes are tested on two datasets of breast cancer cell images containing different level of malignancy. The experimental results show the superiority of the proposed methods when compared with other existing classification and segmentation methods. On the complete image database, the segmentation accuracy in term of cancer nuclei number is over than 97%, reaching an improvement of 3–4% over earlier methods.     

Etude de la respiration, à l’état isolé, des haplotypes de l’abeille tunisienne Apis mellifera intermissa (Buttel Reepen 1906) (Hymenoptera : Apidae)

L’étude de la respiration de l’abeille domestique, Apis mellifera intermissa, à l’état isolé a été réalisée sur les quatre haplotypes existant en Tunisie : A1, A4, A8 et A9 et sous différentes températures : 0°, 10°, 15°, 20°, 25°, 30° et 35°C. Des mesures effectuées sur 1000 abeilles isolées (250 de chaque haplotype) ont montré que la consommation d’oxygène de l’abeille varie en fonction de la température. L’intensité respiratoire des haplotypes augmente progressivement à partir de 0°C pour atteindre son maximum à 15°C. Au-delà de cette température, la consommation d’oxygène de l’abeille diminue progressivement. Pour les basses températures (0° et 10°C), la respiration de l’abeille dépend aussi du facteur génétique et la consommation d’oxygène est faible mais ne s’annule pas. Cette étude a montré qu’il existe une différence de consommation d’oxygène entre les haplotypes A1 et A8 et les haplotypes A4 et A9 pour les basses températures. Le déclenchement de la thermogenèse chez les haplotypes A1 et A8 se produit à 15°C, alors que chez les haplotypes A4 et A9, il a lieu à une température plus basse et qui est de 10°C.     

Antifungal activity of Bacillus thuringiensis strains and their efficacy against the cotton leaf worm Spodoptera littoralis

Bacillus thuringiensis strains that belong to B. thuringiensis, B. kurstaki and soil-isolated B.t. were assessed in the following phytopathogenic: Rhizoctonia solani, that had their mycelial growth decreased after incubation in the presence of the bacterial strains. The bacteria have also pathogenic effect against the insect pest Spodoptera littoralis. The isolate B.t. D-1 and the B.t. kurstaki HD-203 were found to be inhibiting R. solani, the strain B. kurstaki HD-203 displayed the highest percentage of inhibition (64%) and B.t. D-1 showed 49% of inhibition. Antagonistic activity was maintained up to pH 8.5, and the antifungal activity was stable to heat at 70?°C for 1?h. Minimal inhibitory concentrations were 152 and 131?μl/ ml for B.t. D-1 and B. kurstaki HD-203, respectively. The two strains also have high efficacy against S. littoralis larvae, B.t. D-1 gave 70% and the B. kurstaki HD-203 strain gave 80% mortality after seven days of treatment.