Tsagkarakou A.,Greek National Agricultural Research Foundation |
Mouton L.,University Claude Bernard Lyon 1 |
Kristoffersen J.B.,Greek National Agricultural Research Foundation |
Dokianakis E.,Greek National Agricultural Research Foundation |
And 5 more authors.
Bulletin of Entomological Research | Year: 2012
We investigated the molecular diversity of the major agricultural pest Bemisia tabaci and of its associated secondary endosymbionts in Greece. Analyzing mitochondrial DNA, we found that the Q1 (=Q west) is predominant. We used eight microsatellite polymorphic markers to study the genetic structure of 37 populations from mainland and insular Greece, collected on different host species from outdoor and protected crops as well as from non-cultivated plants. In some cases, gene flow was found to be low even between populations separated by just a few kilometres. Bayesian analysis identified two main genetic groups, the first encompassing populations from south Crete and the second composed of populations from north Crete, two other Aegean islands and mainland Greece. Genetic differentiation was not correlated with different host plant species or habitat, or greenhouse versus open environment populations. Gene flow significantly decreased with geographic distance, but no isolation by distance existed when only the samples from mainland Greece or only the samples from Crete were considered. The secondary symbionts Wolbachia and Hamiltonella were present at high frequencies while Arsenophonus, Cardinium and Rickettsia were absent from Greek populations. Multilocus sequence typing of Wolbachia identified two Wolbachia strains. These two strains were found together in most of the populations studied but never in the same host individual. Their role on the observed population structure is discussed. © 2012 Cambridge University Press.
Alexandratos A.,Hellenic Pasteur Institute |
Alexandratos A.,University of Ioannina |
Clos J.,Bernhard Nocht Institute for Tropical Medicine |
Samiotaki M.,Biomedical science Research Center |
And 4 more authors.
Molecular Microbiology | Year: 2013
Overexpression of Leishmania histone H1 (LeishH1) was previously found to cause a promastigote-to-amastigote differentiation handicap, deregulation of cell-cycle progression, and loss of parasite infectivity. The aim of this study was to identify changes in the proteome of LeishH1 overexpressing parasites associated with the avirulent phenotype observed. 2D-gel electrophoresis analysis revealed only a small protein subset of differentially expressed proteins in the LeishH1 overexpressing promastigotes. Among these was the chaperone HSP83, known for its protective role in Leishmania drug-induced apoptosis, which displayed lower translational rates. To investigate if the lower expression levels of HSP83 are associated with the differentiation handicap, we assayed the thermostability of parasites by subjecting them to heat-shock (25°C→37°C), a natural stress-factor occurring during stage differentiation. Heat-shock promoted apoptosis to a greater extent in the LeishH1 overexpressing parasites. Interestingly, these parasites were not only more sensitive to heat-shock but also to drug-induced [Sb(III)] cell-death. In addition, the restoration of HSP83 levels re-established drug resistance, and restored infectivity to LeishH1 overexpressing parasites in the murine J774 macrophage model. Overall, this study suggests that LeishH1 levels are critical for the parasite's stress-induced adaptation within the mammalian host, and highlights the cross-talk between pathways involved in drug resistance, apoptosis and virulence. © 2013 John Wiley & Sons Ltd.
Stenbeck G.,Brunel University |
Lawrence K.M.,Biomedical science Research Center |
Albert A.P.,Biomedical science Research Center
Frontiers in Endocrinology | Year: 2012
A precise control of vesicular trafficking is crucial not only for osteoclastic bone resorption, but also for the crosstalk between osteoclasts and osteoblasts, which regulates bone homeostasis. In addition to the release of growth factors and modulators, such as gluta-mate, flux through the intracellular trafficking routes could also provide the osteoclast with a monitoring function of its resorption activity. To establish the signaling pathways regulating trafficking events in resorbing osteoclasts, we used the bone conserving hormone calcitonin, which has the unique property of inducing osteoclast quiescence. Calcitonin acts through the calcitonin receptor and activates multiple signaling pathways. By monitoring trafficking of a fluorescent low molecular weight probe in mature, bone resorbing osteoclasts we show for the first time that calcitonin blocks endocytosis from the ruffled border by phospholipase C (PLC) activation. Furthermore, we identify a requirement for polyunsaturated fatty acids in endocytic trafficking in osteoclasts. Inhibition of PLC prior to calcitonin treatment restores endocytosis to 75% of untreated rates. This effect is independent of protein kinase C activation and can be mimicked by an increase in intracellular calcium. We thus define an essential role for intracellular calcium levels in the maintenance of endocytosis in osteoclasts. © 2012 Stenbeck, Lawrence and Albert.
Van Den Abbeele J.,Antwerp Institute of Tropical Medicine |
Bourtzis K.,University of Western Greece |
Bourtzis K.,Biomedical science Research Center |
Weiss B.,Yale University |
And 4 more authors.
Journal of Invertebrate Pathology | Year: 2013
To date, IAEA-supported Sterile Insect Technique (SIT) projects for tsetse and trypanosomiasis control have been in areas without human sleeping sickness, but future projects could include areas of actual or potential human disease transmission. In this context it would be imperative that released sterile tsetse flies are incompetent to transmit the disease-causing trypanosome parasite. Therefore, development of tsetse fly strains refractory to trypanosome infection is highly desirable as a simple and effective method of ensuring vector incompetence of the released flies. This new IAEA Coordinated Research Project (CRP) focuses on gaining a deeper knowledge of the tripartite interactions between the tsetse fly vectors, their symbionts and trypanosome parasites. The objective of this CRP is to acquire a better understanding of mechanisms that limit the development of trypanosome infections in tsetse and how these may be enhanced. © 2012 International Atomic Energy Agency.
Dimas A.S.,University of Oxford |
Dimas A.S.,Biomedical science Research Center |
Lagou V.,University of Oxford |
Barker A.,Addenbrookes Hospital |
And 81 more authors.
Diabetes | Year: 2014
Patients with established type 2 diabetes display both b-cell dysfunction and insulin resistance. To define fundamental processes leading to the diabetic state, we examined the relationship between type 2 diabetes risk variants at 37 established susceptibility loci, and indices of proinsulin processing, insulin secretion, and insulin sensitivity. We included data from up to 58,614 nondiabetic subjects with basal measures and 17,327 with dynamic measures. We used additive genetic models with adjustment for sex, age, and BMI, followed by fixed-effects, inverse-variance meta-analyses. Cluster analyses grouped risk loci into five major categories based on their relationship to these continuous glycemic phenotypes. The first cluster (PPARG, KLF14, IRS1, GCKR) was characterized by primary effects on insulin sensitivity. The second cluster (MTNR1B, GCK) featured risk alleles associated with reduced insulin secretion and fasting hyperglycemia. ARAP1 constituted a third cluster characterized by defects in insulin processing. A fourth cluster (TCF7L2, SLC30A8, HHEX/IDE, CDKAL1, CDKN2A/2B) was defined by loci influencing insulin processing and secretion without a detectable change in fasting glucose levels. The final group contained 20 risk loci with no clear-cut associations to continuous glycemic traits. By assembling extensive data on continuous glycemic traits, we have exposed the diverse mechanisms whereby type 2 diabetes risk variants impact disease predisposition. © 2014 by the American Diabetes Association.
Rinotas V.,Agricultural University of Athens |
Rinotas V.,Biomedical science Research Center |
Niti A.,Agricultural University of Athens |
Dacquin R.,CNRS Lyon Institute of Functional Genomics |
And 8 more authors.
Journal of Bone and Mineral Research | Year: 2014
Receptor activator of NF-κB ligand (RANKL) plays a key role in osteoclast-induced bone resorption across a range of degenerative bone diseases, and its specific inhibition has been recently approved as a treatment for women with postmenopausal osteoporosis at high or increased risk of fracture in the United States and globally. In the present study, we generated transgenic mice (TghuRANKL) carrying the human RANKL (huRANKL) genomic region and achieved a physiologically relevant pattern of RANKL overexpression in order to establish novel genetic models for assessing skeletal and extraskeletal pathologies associated with excessive RANKL and for testing clinical therapeutic candidates that inhibit human RANKL. TghuRANKL mice of both sexes developed early-onset bone loss, and the levels of huRANKL expression were correlated with bone resorption and disease severity. Low copy Tg5516 mice expressing huRANKL at low levels displayed a mild osteoporotic phenotype as shown by trabecular bone loss and reduced biomechanical properties. Notably, overexpression of huRANKL, in the medium copy Tg5519 line, resulted in severe early-onset osteoporosis characterized by lack of trabecular bone, destruction of the growth plate, increased osteoclastogenesis, bone marrow adiposity, increased bone remodeling, and severe cortical bone porosity accompanied by decreased bone strength. An even more severe skeletal phenotype developed in the high copy Tg5520 founder with extensive soft tissue calcification. Model validation was further established by evidence that denosumab, an antibody that inhibits human but not murine RANKL, fully corrected the hyper-resorptive and osteoporotic phenotypes of Tg5519 mice. Furthermore, overexpression of huRANKL rescued osteopetrotic phenotypes of RANKL-defective mice. These novel huRANKL transgenic models of osteoporosis represent an important advance for understanding the pathogenesis and treatment of high-turnover bone diseases and other disease states caused by excessive RANKL. © 2014 American Society for Bone and Mineral Research.
Papanikolopoulou A.,National and Kapodistrian University of Athens |
Landt O.,TIB MOLBIOL |
Reczko M.,Biomedical science Research Center |
Drakoulis N.,National and Kapodistrian University of Athens
Review of Clinical Pharmacology and Pharmacokinetics, International Edition | Year: 2010
Recently, common variants on human chromosome 8q24 were found to be associated with prostate cancer risk. While conducting an association study at the Greek population to investigate the frequency and the susceptibility of one SNP, rs6983267, located at the region 3 of chromosome 8q24, to the prostate cancer, we found highly significant correlation (Odds ratio=2.83 and p-value=0.002). Comparing the findings to other studies, conducted in northern Europeans, the population attributable risk (PAR%) and the frequency of the at risk allele (G vs T) were higher at the Greek population with an independent risk for the carriers to develop the disease. ©PHARMAKON-Press.