72 research outputs found
Efficient age determination: how freezing affects eye lens weight of the small rodent species Arvicola terrestris
Age determination of animals by measuring the weight of their eye lenses is a widely used method in wildlife biology. In general, it is recommended to prepare lenses immediately after trapping to avoid errors in the age estimation due to decomposition of lens tissue. However, in many field studies, large numbers of animals need to be trapped over long periods of time in huge areas and by many different field workers. Therefore, the immediate preparation of eye lenses imposes a considerable logistic constraint that could be avoided by prior freezing of trapped animals. To assess the impact of freezing, weights of lens of frozen and unfrozen eyes of 114 Arvicola terrestris were compared pair wise. The frozen lenses weighed at average 3.3% (95% CI: 2.4-4.1%) more than the unfrozen ones from the same animals. Freezing time, weight of lenses and mean temperature of the trapping day as an indicator of decomposition speed did not affect the freezing-induced weight increase. Age estimates based on weights of unfrozen lenses varied between 24 and 445days. Estimates based on frozen lenses were systematically higher. Applying a constant correction factor of 1.033â1 for the weight of frozen lenses corrects this overestimation of age. We conclude that age determination with frozen lenses of small rodents can yield valid age estimates if a correction factor for freezing is applied. Thus, age determination can be organised much more efficiently in field studies, which is highly advantageous for many ecological, agricultural and epidemiological research project
Age, season and spatio-temporal factors affecting the prevalence of Echinococcus multilocularis and Taenia taeniaeformis in Arvicola terrestris
Background: Taenia taeniaeformis and the related zoonotic cestode Echinococcus multilocularis both infect the water vole Arvicola terrestris. We investigated the effect of age, spatio-temporal and season-related factors on the prevalence of these parasites in their shared intermediate host. The absolute age of the voles was calculated based on their eye lens weights, and we included the mean day temperature and mean precipitation experienced by each individual as independent factors. Results: Overall prevalences of E. multilocularis and T. taeniaeformis were 15.1% and 23.4%, respectively, in 856 A. terrestris trapped in the canton ZĂŒrich, Switzerland. Prevalences were lower in young (†3 months: E. multilocularis 7.6%, T. taeniaeformis 17.9%) than in older animals (>7 months: 32.6% and 34.8%). Only 12 of 129 E. multilocularis-infected voles harboured protoscoleces. Similar proportions of animals with several strobilocerci were found in T. taeniaeformis infected voles of <5 months and â„5 months of age (12.8% and 11.9%). Multivariate analyses revealed strong spatio-temporal variations in prevalences of E. multilocularis. In one trapping area, prevalences varied on an exceptional high level of 40.6-78.5% during the whole study period. Low temperatures significantly correlated with the infection rate whereas precipitation was of lower importance. Significant spatial variations in prevalences were also identified for Taenia taeniaeformis. Although the trapping period and the meteorological factors temperature and precipitation were included in the best models for explaining the infection risk, their effects were not significant for this parasite. Conclusions: Our results demonstrate that, besides temporal and spatial factors, low temperatures contribute to the risk of infection with E. multilocularis. This suggests that the enhanced survival of E. multilocularis eggs under cold weather conditions determines the level of infection pressure on the intermediate hosts and possibly also the infection risk for human alveolar echincoccosis (AE). Therefore, interventions against the zoonotic cestode E. multilocularis by deworming foxes may be most efficient if conducted just before and during winter
The Production of a New MAGE-3 Peptide Presented to Cytolytic T Lymphocytes by HLA-B40 Requires the Immunoproteasome
By stimulating human CD8+ T lymphocytes with autologous dendritic cells infected with an adenovirus encoding MAGE-3, we obtained a cytotoxic T lymphocyte (CTL) clone that recognized a new MAGE-3 antigenic peptide, AELVHFLLL, which is presented by HLA-B40. This peptide is also encoded by MAGE-12. The CTL clone recognized MAGE-3âexpressing tumor cells only when they were first treated with IFN-Îł. Since this treatment is known to induce the exchange of the three catalytic subunits of the proteasome to form the immunoproteasome, this result suggested that the processing of this MAGE-3 peptide required the immunoproteasome. Transfection experiments showed that the substitution of ÎČ5i (LMP7) for ÎČ5 is necessary and sufficient for producing the peptide, whereas a mutated form of ÎČ5i (LMP7) lacking the catalytically active site was ineffective. Mass spectrometric analyses of in vitro digestions of a long precursor peptide with either proteasome type showed that the immunoproteasome produced the antigenic peptide more efficiently, whereas the standard proteasome more efficiently introduced cleavages destroying the antigenic peptide. This is the first example of a tumor-specific antigen exclusively presented by tumor cells expressing the immunoproteasome
Mass Spectrometry-based Absolute Quantification of 20S Proteasome Status for Controlled Ex-vivo Expansion of Human Adipose-derived Mesenchymal Stromal/Stem Cells
International audienceIn Brief 20S proteasomes are very heterogeneous protein complexes involved in many cellular processes. In the present study, we combined an MRM-based assay with the production and purification of entire SILAC labelled pro-teasome to monitor absolute quantities of the different 20S proteasome subtypes in various human cells and tissues. This method applied to adipocyte-derived stem cells (ADSCs) amplified under various conditions highlights an increased expression of immunoproteasome when this type of cell is primed with IFNâ„ or amplified in a 20% O 2 environment. Graphical Abstract Highlights âą Design of an MRM assay to determine the absolute quantity and stoichiometry of ubiquitous and tissue-specific human 20S proteasome subtypes. âą Use of purified isotopically labelled 20S proteasome as internal standard for accurate quantification. âą Variation in the expression of immunoproteasome in adipocyte-derived stem cells (ADSCs) grown under different O 2 levels might be causal for change in cells differentiation capacity. âą The status of 20S proteasome during ADSCs expansion might constitute an additional relevant quality control parameter to contribute to predict, among other quality markers, their therapeutic capacity
PIP30/FAM192A is a novel regulator of the nuclear proteasome activator PA28Îł
PA28Îł is a nuclear activator of the 20S proteasome involved in the regulation of several essential cellular processes, such as cell proliferation, apoptosis, nuclear dynamics, and cellular stress response. Unlike the 19S regulator of the proteasome, which specifically recognizes ubiquitylated proteins, PA28Îł promotes the degradation of several substrates by the proteasome in an ATP- and ubiquitin-independent manner. However, its exact mechanisms of action are unclear and likely involve additional partners that remain to be identified. Here we report the identification of a cofactor of PA28Îł, PIP30/FAM192A. PIP30 binds directly and specifically via its C-terminal end and in an interaction stabilized by casein kinase 2 phosphorylation to both free and 20S proteasome-associated PA28Îł. Its recruitment to proteasome-containing complexes depends on PA28Îł and its expression increases the association of PA28Îł with the 20S proteasome in cells. Further dissection of its possible roles shows that PIP30 alters PA28Îł-dependent activation of peptide degradation by the 20S proteasome in vitro and negatively controls in cells the presence of PA28Îł in Cajal bodies by inhibition of its association with the key Cajal body component coilin. Taken together, our data show that PIP30 deeply affects PA28Îł interactions with cellular proteins, including the 20S proteasome, demonstrating that it is an important regulator of PA28Îł in cells and thus a new player in the control of the multiple functions of the proteasome within the nucleus
Problématique des limites entre zone industrielle, zone agricole et zone à bùtir. Un lieu d'accueil et de services pour la zone industrielle de Plan-Les-Ouates (GenÚve, GE)
Ce projet conçu dans la zone industrielle de Plan-les-Ouates veut redonner sa place Ă une certaine forme de nature. Celle-ci Ă©tait marĂ©cageuse et couverte de prairies, puis a Ă©tĂ© drainĂ©e et cultivĂ©e, pour ĂȘtre finalement dĂ©classĂ©e et devenir une ZI. La particularitĂ© de cette derniĂšre Ă©tant d'ĂȘtre cernĂ©e par une zone agricole encore existante et une zone Ă bĂątir toujours plus importante, la question de ses limites s'est vite imposĂ©e. Le plan Ă grande Ă©chelle propose ainsi une certaine permĂ©abilitĂ© et des possibilitĂ©s d'amĂ©nagement sous forme de parcs et d'un cheminement piĂ©ton. Une contamination de verdure se fait par le nord-ouest en continuitĂ© des parties boisĂ©es existantes. La contamination allant dans les deux sens, l'industrie et l'habitat pourraient dĂ©border sur les zones contiguĂ«s. Un axe arborisĂ© plus fin traverse la zone du sud-ouest au nord-est en direction de la partie rĂ©sidentielle. Ă plus petite Ă©chelle, le bĂątiment, situĂ© sur cet axe vert, propose des espaces flexibles de type hĂŽtel industriel permettant Ă des PME de s'installer pour des durĂ©es plus ou moins longues. En relation avec l'habitat, des logements et une crĂšche sont situĂ©s au dernier Ă©tage bĂ©nĂ©ficiant de la vue sur la plaine de l'Aire, le SalĂšve et le Jura. Quant Ă la nature, elle prend la forme d'une façade vĂ©gĂ©tale qui enveloppe le bĂątiment, jouant un rĂŽle de protection solaire, tout en symbolisant la poĂ©tique d'une nature trouvant sa place au sein mĂȘme de l'industrie et de la technologie
Glycogen metabolism and the homeostatic regulation of sleep
In 1995 Benington and Heller formulated an energy hypothesis of sleep centered on a key role of glycogen. It was postulated that a major function of sleep is to replenish glycogen stores in the brain that have been depleted during wakefulness which is associated to an increased energy demand. Astrocytic glycogen depletion participates to an increase of extracellular adenosine release which influences sleep homeostasis. Here, we will review some evidence obtained by studies addressing the question of a key role played by glycogen metabolism in sleep regulation as proposed by this hypothesis or by an alternative hypothesis named "glycogeneticâ hypothesis as well as the importance of the confounding effect of glucocorticoĂŻds. Even though actual collected data argue in favor of a role of sleep in brain energy balance-homeostasis, they do not support a critical and direct involvement of glycogen metabolism on sleep regulation. For instance, glycogen levels during the sleep-wake cycle are driven by different physiological signals and therefore appear more as a marker-integrator of brain energy status than a direct regulator of sleep homeostasis. In support of this we provide evidence that blockade of glycogen mobilization does not induce more sleep episodes during the active period while locomotor activity is reduced. These observations do not invalidate the energy hypothesis of sleep but indicate that underlying cellular mechanisms are more complex than postulated by Benington and Heller
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