INVOLVEMENT OF RESPIRATORY CHAIN IN BIOFILM FORMATION IN PORPHYROMONAS GINGIVALIS

Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011

Hibernation-like state induced by an opioid peptide protects against experimental stroke

BACKGROUND: Delta opioid peptide [D-ala2,D-leU5]enkephalin (DADLE) induces hibernation in summer ground squirrels, and enhances preservation and survival of isolated or transplanted lungs and hearts. In the present study, we investigated the protective effect of DADLE in the central nervous system. RESULTS: Adult Sprague-Dawley rats were pretreated with DADLE (4 mg/kg every 2 h x 4 injections, i.p.) or saline prior to unilateral occlusion of the middle cerebral artery (MCA). Daily behavioral tests revealed that ischemic animals treated with DADLE did not show any significant behavioral dysfunctions compared with saline-treated ischemic animals. Opioid antagonists only transiently inhibited the protective effect of DADLE, indicating the participation of non-opioid mechanisms in DADLE neuroprotection. Histological examination using triphenyltetrazolium chloride (TTC) revealed that brains from ischemic animals treated with DADLE, either alone or with adjuvant opioid blockers, exhibited almost completely intact striata. In contrast, brains from ischemic animals that received saline showed significant infarction in the lateral striatum. Analyses of apoptotic cell death revealed a significant increase in the p-53 mRNA expression in the striatum of ischemic animals that received saline, while those that received DADLE exhibited near normal striatal p-53 expression. This protective effect was accompanied by significant increments in protein levels of glial cell line-derived neurotrophic factor in the striatum of DADLE-treated ischemic animals. CONCLUSION: These results indicate that DADLE protected against necrotic and apoptotic cell death processes associated with ischemia-reperfusion injury. The present study demonstrates that delta opioids are crucially involved in stroke, suggesting that the opioid system is important in the study of brain injury and protection

Batch effect exerts a bigger influence on the rat urinary metabolome and gut microbiota than uraemia: a cautionary tale

Background: Rodent models are invaluable for studying biological processes in the context of whole organisms. The reproducibility of such research is based on an assumption of metabolic similarity between experimental animals, controlled for by breeding and housing strategies that minimise genetic and environmental variation. Here, we set out to demonstrate the effect of experimental uraemia on the rat urinary metabolome and gut microbiome but found instead that the effect of vendor shipment batch was larger in both areas than that of uraemia. Results: Twenty four Wistar rats obtained from the same commercial supplier in two separate shipment batches underwent either subtotal nephrectomy or sham procedures. All animals undergoing subtotal nephrectomy developed an expected uraemic phenotype. The urinary metabolome was studied using 1 H-NMR spectroscopy and found to vary significantly between animals from different batches, with substantial differences in concentrations of a broad range of substances including lactate, acetate, glucose, amino acids, amines and benzoate derivatives. In animals from one batch, there was a complete absence of the microbiome-associated urinary metabolite hippurate, which was present in significant concentrations in animals from the other batch. These differences were so prominent that we would have drawn quite different conclusions about the effect of uraemia on urinary phenotype depending on which batch of animals we had used. Corresponding differences were seen in the gut microbiota between animals in different batches when assessed by the sequencing of 16S rRNA gene amplicons, with higher alpha diversity and different distributions of Proteobacteria subtaxa and short-chain fatty acid producing bacteria in the second batch compared to the first. Whilst we also demonstrated differences in both the urinary metabolome and gut microbiota associated with uraemia, these effects were smaller in size than those associated with shipment batch. Conclusions: These results challenge the assumption that experimental animals obtained from the same supplier are metabolically comparable, and provide metabolomic evidence that batch-to-batch variations in the microbiome of experimental animals are significant confounders in an experimental study. We discuss strategies for reducing such variability and the need for transparency in research publications about the supply of experimental animals

Benefits of sea buckthorn (Hippophae rhamnoides) pulp oil-based mouthwash on oral health

International audienceAim The purpose of this study was to conduct phytochemical analysis of sea buckthorn pulp oil and to evaluate the antimicrobial, anti-biofilm and antioxidant activities of its mouthwash form.Methods and Results Fatty acid composition of the sea buckthorn pulp oil was determined by GC-MS analysis, which revealed that, mono-unsaturated fatty acid, palmitoleic acid and saturated fatty acid, palmitic acid, were the major constituents. The antimicrobial and the anti-biofilm capacities of sea buckthorn pulp oil mouthwash form were evaluated against Streptococcus gordonii, Porphyromonas gingivalis, Actinomyces viscosus and Candida albicans, according to the European Norms, and the Biofilm Ring Test ® , respectively. These activities were then compared with those of chlorhexidine and herbal mouthwashes. The sea buckthorn-based mouthwash was bactericidal against S. gordonii and P. gingivalis, bacteriostatic against A. viscosus and showed no antifungal effect. Regardless of the strains used, complete inhibition of biofilm formation was achieved. The antioxidant activity of this experimental mouthwash was also assessed by DPPH and NBT assays.Conclusion Sea buckthorn mouthwash showed anti-biofilm activities against select single and multiple oral bacterial species

Batch effect exerts a bigger influence on the rat urinary metabolome and gut microbiota than uraemia: a cautionary tale

Background: Rodent models are invaluable for studying biological processes in the context of whole organisms. The reproducibility of such research is based on an assumption of metabolic similarity between experimental animals, controlled for by breeding and housing strategies that minimise genetic and environmental variation. Here, we set out to demonstrate the effect of experimental uraemia on the rat urinary metabolome and gut microbiome but found instead that the effect of vendor shipment batch was larger in both areas than that of uraemia. Results: Twenty four Wistar rats obtained from the same commercial supplier in two separate shipment batches underwent either subtotal nephrectomy or sham procedures. All animals undergoing subtotal nephrectomy developed an expected uraemic phenotype. The urinary metabolome was studied using 1 H-NMR spectroscopy and found to vary significantly between animals from different batches, with substantial differences in concentrations of a broad range of substances including lactate, acetate, glucose, amino acids, amines and benzoate derivatives. In animals from one batch, there was a complete absence of the microbiome-associated urinary metabolite hippurate, which was present in significant concentrations in animals from the other batch. These differences were so prominent that we would have drawn quite different conclusions about the effect of uraemia on urinary phenotype depending on which batch of animals we had used. Corresponding differences were seen in the gut microbiota between animals in different batches when assessed by the sequencing of 16S rRNA gene amplicons, with higher alpha diversity and different distributions of Proteobacteria subtaxa and short-chain fatty acid producing bacteria in the second batch compared to the first. Whilst we also demonstrated differences in both the urinary metabolome and gut microbiota associated with uraemia, these effects were smaller in size than those associated with shipment batch. Conclusions: These results challenge the assumption that experimental animals obtained from the same supplier are metabolically comparable, and provide metabolomic evidence that batch-to-batch variations in the microbiome of experimental animals are significant confounders in an experimental study. We discuss strategies for reducing such variability and the need for transparency in research publications about the supply of experimental animals

Ultrastructure and melatonin 1a receptor distribution in the ovaries of African ostrich chicks

Healthy 90-day-old ostrich chicks were used in the present study. The ultrastructure and melatonin 1a receptor (MT1) distribution in the ovaries of ostrich chicks was observed by transmission electron microscope and light microscope. The results showed that the ostrich chick ovary contained primordial follicles, primary follicles and secondary follicles, but no mature follicles. There are some unique ultrastructural characteristics observed in the secondary follicle, such as the cortical granule, which was located in cytoplasm beside the nucleus and appeared first in the oocyte. The zona radiata appeared in the secondary follicle, and there was an obvious vitelline membrane. There were intraovarian rete, connecting rete, and extraovarian rete in the ovaries of ostrich chicks. This is the first study that provides immunohistochemical evidence for the localization of the melatonin MT1 in the ostrich chick ovary. The germinal epithelium, follicular cell layer of every grade of follicle, cytoplasm of the oocyte and interstitial cells all expressed MT1. The expression of positive immunoreactivity materials was the strongest in the follicular cell layer of the primordial follicle and germinal epithelium, was weaker in the follicular cell layer of the primary follicle and secondary follicle, and was weakest in the oocytes of all grades of follicle. In addition, the extraovarian rete displayed strong positive expression of MT1, while there was no positive expression in the intraovarian rete or connecting rete. The positive expression of MT1 immunoreactivity in the ovary was very strong, implying that the ovary is an important organ for synthesizing MT1