Exploration Behaviour Is Not Associated with Chick Provisioning in Great Tits

In biparental systems, members of the same pair can vary substantially in the amount of parental care they provide to offspring. The extent of this asymmetry should depend on the relative costs and benefits of care. Individual variation in personality is likely to influence this trade-off, and hence is a promising candidate to explain differences in care. In addition, plasticity in parental care may also be associated with personality differences. Using exploration behaviour (EB) as a measure of personality, we investigated these possibilities using both natural and experimental data from a wild population of great tits (Parus major). Contrary to predictions, we found no association between EB and natural variation in provisioning behaviour. Nor was EB linked to responsiveness to experimentally increased brood demand. These results are initially surprising given substantial data from other studies suggesting personality should influence investment in parental care. However, they are consistent with a recent study showing selection on EB is weak and highly context-specific in the focal population. This emphasises the difficulty faced by personality studies attempting to make predictions based on previous work, given that personalities often vary among populations of the same species

HLA-C and HIV-1: friends or foes?

The major histocompatibility complex class I protein HLA-C plays a crucial role as a molecule capable of sending inhibitory signals to both natural killer (NK) cells and cytotoxic T lymphocytes (CTL) via binding to killer cell Ig-like receptors (KIR). Recently HLA-C has been recognized as a key molecule in the immune control of HIV-1. Expression of HLA-C is modulated by a microRNA binding site. HLA-C alleles that bear substitutions in the microRNA binding site are more expressed at the cell surface and associated with the control of HIV-1 viral load, suggesting a role of HLA-C in the presentation of antigenic peptides to CTLs. This review highlights the role of HLA-C in association with HIV-1 viral load, but also addresses the contradiction of the association between high cell surface expression of an inhibitory molecule and strong cell-mediated immunity. To explore additional mechanisms of control of HIV-1 replication by HLA-C, we address specific features of the molecule, like its tendency to be expressed as open conformer upon cell activation, which endows it with a unique capacity to associate with other cell surface molecules as well as with HIV-1 proteins

HIV-1 Env associates with HLA-C free-chains at the cell membrane modulating viral infectivity

HLA-C has been demonstrated to associate with HIV-1 envelope glycoprotein (Env). Virions lacking HLA-C have reduced infectivity and increased susceptibility to neutralizing antibodies. Like all others MHC-I molecules, HLA-C requires \u3b22-microglobulin (\u3b22m) for appropriate folding and expression on the cell membrane but this association is weaker, thus generating HLA-C free-chains on the cell surface. In this study, we deepen the understanding of HLA-C and Env association by showing that HIV-1 specifically increases the amount of HLA-C free chains, not bound to \u3b22m, on the membrane of infected cells. The association between Env and HLA-C takes place at the cell membrane requiring \u3b22m to occur. We report that the enhanced infectivity conferred to HIV-1 by HLA-C specifically involves HLA-C free chain molecules that have been correctly assembled with \u3b22m. HIV-1 Env-pseudotyped viruses produced in the absence of \u3b22m are less infectious than those produced in the presence of \u3b22m. We hypothesize that the conformation and surface expression of HLA-C molecules could be a discriminant for the association with Env. Binding stability to \u3b22m may confer to HLA-C the ability to preferentially act either as a conventional immune-competent molecule or as an accessory molecule involved in HIV-1 infectivity

Consumer exposure to chromium-6

Afgelopen jaren was er veel aandacht voor medewerkers die zijn blootgesteld aan chroom-6 door onderhoud aan defensiematerieel en treinen. Ook is chroom-6 als bestanddeel van roestwerende verf gebruikt voor vastgoed zoals huizen en kantoren. Blootstelling aan deze gevaarlijke stof kan schadelijk zijn voor de gezondheid. De vraag is of mensen in hun dagelijks leven via alledaagse producten blootstaan aan gevaarlijke hoeveelheden chroom-6. Uit onderzoek van het RIVM blijkt dat deze blootstelling laag is en geen risico voor de gezondheid vormt. Veel producten mogen inmiddels geen chroom-6 meer bevatten. Alleen onbedoeld kunnen consumenten via de lucht aan chroom-6 blootstaan wanneer sommige chroomhoudende producten worden bewerkt, bijvoorbeeld door ze te lassen, zagen, schuren of verbranden. Als dit niet gebeurt, komt er geen chroom-6 uit de producten vrij en is er geen risico. Consumentenproducten die kleine hoeveelheden chroom-6 bevatten zijn bijvoorbeeld gemaakt van gechromeerd metaal (zoals kranen, knoppen). Daarnaast gaat het om producten waarin het chroom-6 als onzuiverheid aanwezig is of als conserveringsmiddel wordt gebruikt, zoals in cement en tijdens het looien van leer, of om hout te beschermen tegen verwering. In het onderzoek is ook gekeken naar een mogelijke blootstelling via voedsel, drinkwater en lucht. Voedsel bevat van nature zeer kleine hoeveelheden chroom-3, de minder schadelijke vorm van chroom. In water en lucht komen ook slechts kleine hoeveelheden voor. Het is bekend dat blootstelling aan chroom-6 via de huid contactallergie kan veroorzaken. De concentraties in consumentenproducten zijn dermate laag dat ze, voor zover bekend, geen allergische reacties veroorzaken. Uit onderzoeken op de werkplek is bekend dat onder andere longkanker, maar ook andere ziekten kunnen ontstaan nadat mensen chroom-6 hebben ingeademd. Het is onvoldoende bekend in welke mate consumenten via de genoemde onbedoelde, niet-professionele handelingen blootstaan aan chroom-6. Daarom is het van belang consumenten bewust te maken van de mogelijke gevaren als zij zelf producten met chroom willen bewerken. Het is bijvoorbeeld verboden om bewerkt hout te verbranden.In recent years, the issue of employees who have been exposed to chromium-6 when repairing defence equipment and trains has come to the fore. Chromium-6 is also used as an ingredient in rust-resistant paint for buildings such as houses and offices. Exposure to this hazardous substance can be harmful to human health. The question is whether people are exposed to dangerous levels of chromium-6 through everyday products in their day-to-day lives. Recent RIVM research has shown that this exposure is low and does not pose a risk to health. Chromium-6 is no longer permitted in many products. Furthermore, consumers can only be exposed to chromium-6 unintentionally, through the air when certain products containing chromium-6 are being processed, (e.g. welding, sawing, sanding or burning). In the absence of such activities, no chromium-6 is released from these products and there is no risk to consumers. Consumer products made from chromed metal contain small amounts of chromium-6 (such as taps or buttons). In addition, some products that contain chromium may contain chromium-6 as an impurity, and chromium-6 is sometimes used as a preservative in cement and during the tanning of leather, or to protect wood against weathering. The study also looked at possible exposure via food, drinking water and air. Food naturally contains chromium-3, a less harmful form of chromium, but only in very small amounts. Very small quantities may also be present in water and air. Exposure to chromium-6 can cause a contact allergy when people are exposed to it via the skin. However, the concentrations in consumer products are so low that, as far as we know, they do not cause any allergic reactions. Workplace studies have shown that various forms of cancer may develop if chromium-6 is inhaled. At present, we have insufficient knowledge of the extent to which consumers are unintentionally exposed to chromium-6 due to the non-professional activities described above. It is therefore important that consumers are made aware of the potential dangers if they are working with chromium-based products themselves. For example, people should be made aware that it is forbidden to burn processed wood.Ministerie van VW

Blootstelling van consumenten aan chroom-6

Afgelopen jaren was er veel aandacht voor medewerkers die zijn blootgesteld aan chroom-6 door onderhoud aan defensiematerieel en treinen. Ook is chroom-6 als bestanddeel van roestwerende verf gebruikt voor vastgoed zoals huizen en kantoren. Blootstelling aan deze gevaarlijke stof kan schadelijk zijn voor de gezondheid. De vraag is of mensen in hun dagelijks leven via alledaagse producten blootstaan aan gevaarlijke hoeveelheden chroom-6. Uit onderzoek van het RIVM blijkt dat deze blootstelling laag is en geen risico voor de gezondheid vormt. Veel producten mogen inmiddels geen chroom-6 meer bevatten. Alleen onbedoeld kunnen consumenten via de lucht aan chroom-6 blootstaan wanneer sommige chroomhoudende producten worden bewerkt, bijvoorbeeld door ze te lassen, zagen, schuren of verbranden. Als dit niet gebeurt, komt er geen chroom-6 uit de producten vrij en is er geen risico. Consumentenproducten die kleine hoeveelheden chroom-6 bevatten zijn bijvoorbeeld gemaakt van gechromeerd metaal (zoals kranen, knoppen). Daarnaast gaat het om producten waarin het chroom-6 als onzuiverheid aanwezig is of als conserveringsmiddel wordt gebruikt, zoals in cement en tijdens het looien van leer, of om hout te beschermen tegen verwering. In het onderzoek is ook gekeken naar een mogelijke blootstelling via voedsel, drinkwater en lucht. Voedsel bevat van nature zeer kleine hoeveelheden chroom-3, de minder schadelijke vorm van chroom. In water en lucht komen ook slechts kleine hoeveelheden voor. Het is bekend dat blootstelling aan chroom-6 via de huid contactallergie kan veroorzaken. De concentraties in consumentenproducten zijn dermate laag dat ze, voor zover bekend, geen allergische reacties veroorzaken. Uit onderzoeken op de werkplek is bekend dat onder andere longkanker, maar ook andere ziekten kunnen ontstaan nadat mensen chroom-6 hebben ingeademd. Het is onvoldoende bekend in welke mate consumenten via de genoemde onbedoelde, niet-professionele handelingen blootstaan aan chroom-6. Daarom is het van belang consumenten bewust te maken van de mogelijke gevaren als zij zelf producten met chroom willen bewerken. Het is bijvoorbeeld verboden om bewerkt hout te verbranden

Ubiquitin crosstalk connecting cellular processes

The polypeptide ubiquitin is used in many processes as different as endocytosis, multivesicular body formation, and regulation of gene transcription. Conjugation of a single ubiquitin moiety is typically used in these processes. A polymer of ubiquitin moieties is required for tagging proteins for proteasomal degradation. Besides its role in protein degradation, ubiquitin is also engaged as mono- or polymer in intracellular signalling and DNA repair. Since free ubiquitin is present in limiting amounts in cells, changes in the demands for ubiquitin in any of these processes is likely to indirectly affect other ubiquitin modifications. For example, proteotoxic stress strongly increases poly-ubiquitylated proteins at the cost of mono-ubiquitylated histones resulting in chromatin remodelling and altered transcription. Here we discuss the interconnection between ubiquitin-dependent processes and speculate on the functional significance of the ubiquitin equilibrium as a signalling route translating cellular stress into molecular responses

A meta-analysis of correlated behaviours with implications for behavioural syndromes: Mean effect size, publication bias, phylogenetic effects and the role of mediator variables

In evolutionary and behavioural ecology, increasing attention is being paid to the fact that functionally distinct behaviours are often not independent from each other. Such phenomenon is labelled as behavioural syndrome and is usually demonstrated by phenotypic correlations between behaviours like activity, exploration, aggression and risk-taking across individuals in a population. However, published studies disagree on the strength, and even on the existence of such relationships. To make general inferences from this mixed evidence, we quantitatively reviewed the literature using modern meta-analytic approaches. Based on a large dataset, we investigated the overall relationship between behaviours that are expected to form a syndrome and tested which factors can mediate heterogeneities in study outcomes. The average strength of the phenotypic correlation between behaviours was weak; we found no effect of the phylogeny of species but did observe significant publication bias. However, even accounting for this bias, the mean effect size was positive and statistically different from zero (r = 0. 198). Effect sizes showed considerable heterogeneity within species, implying a role for population-specific adaptation to environmental factors and/or between-study differences in research design. There was a significant positive association between absolute effect size and repeatability of behaviours, suggesting that within-individual variation of behavioural traits can set up an upper limit for the strength of the detected phenotypic correlations. Moreover, spatial overlap between the contexts in which different behaviours were assayed increased the magnitude of the association. The small effect size for the focal relationship implies that a huge sample size would be required to demonstrate a correlation between behaviours with sufficient statistical power, which is fulfilled only in very few studies. This suggests that behavioural syndromes often remain undetected and unpublished. Collectively, our meta-analysis revealed a number of points that might be worth to consider in the future study of behavioural syndromes. © 2012 The Author(s).Peer Reviewe