Long tree‐ring chronologies reveal 20th century increases in water‐use efficiency but no enhancement of tree growth at five Iberian pine forests

We investigated the tree growth and physiological response of five pine forest stands in relation to changes in atmospheric CO₂ concentration (c_a) and climate in the Iberian Peninsula using annually resolved width and δ¹³C tree‐ring chronologies since ad 1600. ¹³C discrimination (Δ≈c_i/c_a), leaf intercellular CO₂ concentration (c_i) and intrinsic water‐use efficiency (iWUE) were inferred from δ¹³C values. The most pronounced changes were observed during the second half of the 20th century, and differed between stands. Three sites kept a constant c_i/c_a ratio, leading to significant c_i and iWUE increases (active response to c_a); whereas a significant increase in c_i/c_a resulted in the lowest iWUE increase of all stands at a relict Pinus uncinata forest site (passive response to c_a). A significant decrease in c_i/c_a led to the greatest iWUE improvement at the northwestern site. We tested the climatic signal strength registered in the δ¹³C series after removing the low‐frequency trends due to the physiological responses to increasing c_a. We found stronger correlations with temperature during the growing season, demonstrating that the physiological response to c_a changes modulated δ¹³C and masked the climate signal. Since 1970 higher δ¹³C values revealed iWUE improvements at all the sites exceeding values expected by an active response to the c_a increase alone. These patterns were related to upward trends in temperatures, indicating that other factors are reinforcing stomatal closure in these forests. Narrower rings during the second half of the 20th century than in previous centuries were observed at four sites and after 1970 at all sites, providing no evidence for a possible CO₂‘fertilization’ effect on growth. The iWUE improvements found for all the forests, reflecting both a c_a rise and warmer conditions, seem to be insufficient to compensate for the negative effects of the increasing water limitation on growth.     

Forecasting ecological and evolutionary strategies to global change: an example from habitat selection by lemmings

Ecologists and evolutionary biologists must develop theories that can predict the consequences of global warming and other impacts on Earth's biota. Theories of adaptive habitat selection are particularly promising because they link distribution and density with fitness. The evolutionarily stable strategy that emerges from adaptive habitat choice is given by the system's habitat isodar, the graph of densities in pairs of habitats such that the expectation of fitness is the same in each. We illustrate how isodars can be converted into adaptive landscapes of habitat selection that display the density‐ and frequency‐dependent fitness of competing strategies of habitat use. The adaptive landscape varies with the abundance of habitats and can thus be used to predict future adaptive distributions of individuals under competing scenarios of habitat change. Application of the theory to three species of Arctic rodents living on Herschel Island in the Beaufort Sea predicts changes in selection gradients as xeric upland increases in frequency with global warming. Selection gradients will become more shallow for brown lemming (Lemmus trimucronatus) and tundra vole (Microtus oeconomus) strategies that preferentially exploit mesic habitat. Climate change will cause selection gradients for the alternative strategy of using mostly xeric habitat to become much steeper. Meanwhile, the adaptive landscape for collared lemmings (Dicrostonyx groenlandicus), which specialize on xeric Dryas‐covered upland, will become increasingly convex. Changes in the adaptive landscapes thus predict expanding niches for Lemmus and Microtus, and a narrower niche for Dicrostonyx. The ability to draw adaptive landscapes from current patterns of distribution represents one of the few methods available to forecast the consequences of climate change on the future distribution and evolution of affected species.     

Extreme climatic events reduce ocean productivity and larval supply in a tropical reef ecosystem

Increasing ocean temperatures due to global warming are predicted to have negative effects on coral reef fishes. El Niño events are associated with elevated water temperatures at large spatial (1000s of km) and temporal (annual) scales, providing environmental conditions that enable temperature effects on reef fishes to be tested directly. We compared remote sensing data of sea surface temperature (SST) anomalies, surface current flow and chlorophyll‐a (Chl‐a) concentration with monthly patterns in larval supply of coral reef fishes in nearshore waters around Rangiroa Atoll (French Polynesia) from January 1996 to March 2000. This time included an intense El Niño (April 1997–May 1998) event between two periods of La Niña (January–March 1996 and August 1998–March 2000) conditions. There was a strong relationship between the timing of the El Niño event, current flow, ocean productivity (as measured by Chl‐a) and larval supply. In the warm conditions of the event, there was an increase in the SST anomaly index up to 3.5 °C above mean values and a decrease in the strength of the westward surface current toward the reef. These conditions coincided with low concentrations of Chl‐a (mean: 0.06 mg m^?3, SE ± 0.004) and a 51% decline in larval supply from mean values. Conversely, during strong La Niña conditions when SST anomalies were almost 2 °C below mean values and there was a strong westward surface current, Chl‐a concentration was 150% greater than mean values and larval supply was 249% greater. A lag in larval supply suggested that productivity maybe affecting both the production of larvae by adults and larval survival. Our results suggest that warming temperatures in the world's oceans will have negative effects on the reproduction of reef fishes and survival of their larvae within the plankton, ultimately impacting on the replenishment of benthic populations.     

The Machado-Joseph disease deubiquitylase ATX-3 couples longevity and proteostasis

Protein ubiquitylation is a key post-translational control mechanism contributing to different physiological processes, such as signal transduction and ageing. The size and linkage of a ubiquitin chain, which determines whether a substrate is efficiently targeted for proteasomal degradation, is determined by the interplay between ubiquitylation and deubiquitylation. A conserved factor that orchestrates distinct substrate-processing co-regulators in diverse species is the ubiquitin-selective chaperone CDC-48 (also known as p97). Several deubiquitylation enzymes (DUBs) have been shown to interact with CDC-48/p97, but the mechanistic and physiological relevance of these interactions remained elusive. Here we report a synergistic cooperation between CDC-48 and ATX-3 (the Caenorhabditis elegans orthologue of ataxin-3) in ubiquitin-mediated proteolysis and ageing regulation. Surprisingly, worms deficient for both cdc-48.1 and atx-3 demonstrated extended lifespan by up to 50%, mediated through the insulin-insulin-like growth factor 1 (IGF-1) signalling pathway. As lifespan extension specifically depends on the deubiquitylation activity of ATX-3, our findings identify a mechanistic link between protein degradation and longevity through editing of the ubiquitylation status of substrates involved in insulin-IGF-1 signalling.     

Curiosities of the methicillin-resistant Staphylococcus aureus survey - possibility of pseudo-outbreak and transmission to household contacts

Methicillin-resistant Staphylococcus aureus (MRSA) is currently one of the most prevalent antibiotic-resistant pathogens in hospitals, but it is also emerging as a community-acquired pathogen. We analysed the clinical and microbiological data of the patients in a county teaching hospital regarding MRSA. During the examination period (1996-2010), four outbreaks and one pseudo-outbreak occurred. It also became evident that health care workers and their families are possibly at risk of becoming carriers of MRSA. The importance of the molecular epidemiological investigation (pulsed-field gel-electrophoresis (PFGE)) typing and hygienic measures in order to detect and control MRSA outbreaks must be emphasised. Following infection control guidelines seems to be cost-effective method of controlling the nosocomial transmission of MRSA.     

Beyond DNA: integrating inclusive inheritance into an extended theory of evolution

Many biologists are calling for an 'extended evolutionary synthesis' that would 'modernize the modern synthesis' of evolution. Biological information is typically considered as being transmitted across generations by the DNA sequence alone, but accumulating evidence indicates that both genetic and non-genetic inheritance, and the interactions between them, have important effects on evolutionary outcomes. We review the evidence for such effects of epigenetic, ecological and cultural inheritance and parental effects, and outline methods that quantify the relative contributions of genetic and non-genetic heritability to the transmission of phenotypic variation across generations. These issues have implications for diverse areas, from the question of missing heritability in human complex-trait genetics to the basis of major evolutionary transitions.     

Regulatory T Lymphocytes Are Associated with Less Aggressive Histologic Features in Microsatellite-Unstable Colorectal Cancers

Background

Colorectal cancers (CRCs) with microsatellite instability (MSI) are associated with a good prognosis and a high density of tumor-infiltrating lymphocytes (TILs). We have undertaken to determine the link between TIL densities and MSI CRC histologic features.

Patients and Methods

Using tissue microarrays, T-cell sub-population infiltration, including T cells (CD3), cytotoxic T cells (CD8) and regulatory T cells (FoxP3) were studied in 86 MSI CRCs. We separately analyzed TILs of the stromal and epithelial compartments in the tumor center, the tumoral invasion margin and associated normal tissue.

Results

For FoxP3+ TIL density in the tumor center stromal compartment, we found a strong negative correlation with T4 stage (p = 0.01), node invasion (p<0.001) and VELIPI (vascular emboli, lymphatic invasion and perinervous invasion) criteria (p = 0.002).

Conclusion

The strong correlation between regulatory T cell density and the absence of VELIPI criteria suggests that this sub-group of T cells is preferentially associated with less invasive tumors.     

Knowledge Transfer on Complex Social Interventions in Public Health: A Scoping Study

Objectives

Scientific knowledge can help develop interventions that improve public health. The objectives of this review are (1) to describe the status of research on knowledge transfer strategies in the field of complex social interventions in public health and (2) to identify priorities for future research in this field.

Method

A scoping study is an exploratory study. After searching databases of bibliographic references and specialized periodicals, we summarized the relevant studies using a predetermined assessment framework. In-depth analysis focused on the following items: types of knowledge transfer strategies, fields of public health, types of publics, types of utilization, and types of research specifications.

Results

From the 1,374 references identified, we selected 26 studies. The strategies targeted mostly administrators of organizations and practitioners. The articles generally dealt with instrumental utilization and most often used qualitative methods. In general, the bias risk for the studies is high.

Conclusion

Researchers need to consider the methodological challenges in this field of research in order to improve assessment of more complex knowledge transfer strategies (when they exist), not just diffusion/dissemination strategies and conceptual and persuasive utilization.     

The effect of mating system on invasiveness: some genetic load may be advantageous when invading new environments

The role of adaptation in determining invasion success has been acknowledged recently, notably through the accumulation of case studies of rapid evolution during bioinvasions. Despite this growing body of empirical evidence, there is still a need to develop the theoretical background of invasions with adaptation. Specifically, the impact of mating system on the dynamics of adaptation during invasion of a new environment remains only partially understood. Here, we analyze a simulation demo-genetic model of bioinvasion accounting for partial asexuality rates. We simulate two levels of recurrent immigration from a source population at mutation–drift–selection equilibrium to a new empty environment with a different adaptive landscape (black-hole sink). Adaptation relies on a quantitative trait coded explicitly by 10 loci under mutation, selection and genetic drift. Using this model, we confirm previous results on the positive effects on invasiveness of migration, mutation and similarity of local phenotypic optima. We further show how the invasion dynamics of the introduced population is affected by the rate of asexuality. Purely asexual species have lower invasion success in terms of probability and time to invasion than species with other mating systems. Among species with mixed mating systems, the greatest invasiveness is observed for species with high asexual rates. We suggest that this pattern is due to inflated genetic variance in the source population through the Hill-Robertson effect (i.e., clonal interference). An interesting consequence is that species with the highest genetic load in their source environment have greatest invasiveness in the new environment.