Limpet grazing and loss of Ascophyllum nodosum canopies on decadal time scales

The role of limpet grazing in preventing the development of algal canopies is a recurrent theme in intertidal ecology. Less is known about interactions of limpets with the long-term dynamics of established canopies. Aerial photographs indicate that intertidal canopy cover has declined over the past 44 yr in Strangford Lough, Northern Ireland. There has been a loss of the previously continuous cover of Ascophyllum nodosum (L.) Le Jolis in the mid-shore. A barnacles dominated assemblage now fills gaps in the A. nodosum canopy. The rates at which barnacle patches become established and grow have increased since 1990. Changes in canopy cover have been accompanied by increases in limpet densities since the 1980s. Measurements between 2003 and 2004 showed no increase in length of A. nodosum fronds when limpets Patella vulgata had access to the algal holdfasts. In contrast, when limpets were experimentally excluded from the holdfasts, there was net frond growth. In the Isle of Man, which is climatically similar to Strangford Lough but has fewer limpets, growth occurred regardless of limpet grazing. The breaking force for A. nodosum declined with increasing local densities of limpets. A. nodosum is a sheltered shore species, potentially vulnerable to changes in wave exposure. There is no evidence, however, that Strangford Lough has become windier over the past 3 decades. Variation in wave exposure among locations within the lough was not related to rates of barnacle patch creation or expansion, Limpet population density has increased following a series of mild winters. Climate change may have a role in causing canopy loss, not by direct effects on the limpet populations.

Loss of the LAT adaptor converts antigen-responsive T cells into pathogenic effectors that function independently of the T cell receptor.

Despite compromised T cell antigen receptor (TCR) signaling, mice in which tyrosine 136 of the adaptor linker for activation of T cells (LAT) was constitutively mutated (Lat(Y136F) mice) accumulate CD4(+) T cells that trigger autoimmunity and inflammation. Here we show that equipping postthymic CD4(+) T cells with LATY136F molecules or rendering them deficient in LAT molecules triggers a lymphoproliferative disorder dependent on prior TCR engagement. Therefore, such disorders required neither faulty thymic T cell maturation nor LATY136F molecules. Unexpectedly, in CD4(+) T cells recently deprived of LAT, the proximal triggering module of the TCR induced a spectrum of protein tyrosine phosphorylation that largely overlapped the one observed in the presence of LAT. The fact that such LAT-independent signals result in lymphoproliferative disorders with excessive cytokine production demonstrates that LAT constitutes a key negative regulator of the triggering module and of the LAT-independent branches of the TCR signaling cassette.

‘A planet of confusion and debate’: children's and young people's response to the news coverage of Pluto's loss of planetary status

Despite calls that the school science curriculum should develop among students an ability to understand and respond critically to science-related media reports, very little research has been directed toward an important matter relevant to that aim, namely, how children and young people, untutored, react to science in the news. This study sought, in the context of media coverage of the debate surrounding the planetary status of Pluto, to explore this issue. A questionnaire, completed by 350 students aged between eight and 18, showed just over half of the children and young people were able to write relevantly about the subject though it was the gist not the detail of the story they recounted. There was evidence, nonetheless, that this media-acquired information functioned as active rather than passive knowledge. Students demonstrated relatively few misconceptions and those presented were predominately pre-existing rather than media-derived. As with the wider public, many of the children and young people held strong opinions on Pluto's loss of planethood. Such responses diminished with age, however, with older students expressing a degree of indifference. The paper concludes with a discussion of some implications of the research findings for science instruction.

Progressive loss of epidermal growth factor receptor in a subpopulation of breast cancers: implications in target-directed therapeutics

Understanding the molecular etiology and heterogeneity of disease has a direct effect on cancer therapeutics. To identify novel molecular changes associated with breast cancer progression, we conducted phosphoproteomics of the MCF10AT model comprising isogenic, ErbB2- and ErbB3-positive, xenograft-derived cell lines that mimic different stages of breast cancer. Using in vitro animal model and clinical breast samples, our study revealed a marked reduction of epidermal growth factor receptor (EGFR) expression with breast cancer progression. Such diminution of EGFR expression was associated with increased resistance to Gefitinib/Iressa in vitro. Fluorescence in situ hybridization showed that loss of EGFR gene copy number was one of the key mechanisms behind the low/null expression of EGFR in clinical breast tumors. Statistical analysis on the immunohistochemistry data of EGFR expression from 93 matched normal and breast tumor samples showed that (a) diminished EGFR expression could. be detected as early as in the preneoplastic lesion (ductal carcinoma in situ) and this culminated in invasive carcinomas; (b) EGFR expression levels could distinguish between normal tissue versus carcinoma in situ and invasive carcinoma with high statistical significance (P

Characterizing capacity loss of lithium oxygen batteries by impedance spectroscopy

Polymer based carbon aerogels were prepared by synthesis of a resorcinol formaldehyde gel followed by pyrolysis at 1073K under Ar and activation of the resultant carbon under CO2 at different temperatures. The prepared carbon aerogels were used as active materials in the preparation of cathode electrodes for lithium oxygen cells and the electrochemical performance of the cells was evaluated by galvanostatic charge/discharge cycling and electrochemical impedance measurements. It was shown that the storage capacity and discharge voltage of a Li/O2 cell strongly depend on the porous structure of the carbon used in cathode. EIS results also showed that the shape and value of the resistance in the impedance spectrum of a Li/O2 cell are strongly affected by the porosity of carbon used in the cathode. Porosity changes due to the build up of discharge products hinder the oxygen and lithium ion transfer into the electrode, resulting in a gradual increase in the cell impedance with cycling. The discharge capacity and cycle life of the battery decrease significantly as its internal resistance increases with charge/discharge cycling.

Loss of functionally unique species may gradually undermine ecosystems

Functionally unique species contribute to the functional diversity of natural systems, often enhancing ecosystem functioning. An abundance of weakly interacting species increases stability in natural systems, suggesting that loss of weakly linked species may reduce stability. Any link between the functional uniqueness of a species and the strength of its interactions in a food web could therefore have simultaneous effects on ecosystem functioning and stability. Here, we analyse patterns in 213 real food webs and show that highly unique species consistently tend to have the weakest mean interaction strength per unit biomass in the system. This relationship is not a simple consequence of the interdependence of both measures on body size and appears to be driven by the empirical pattern of size structuring in aquatic systems and the trophic position of each species in the web. Food web resolution also has an important effect, with aggregation of species into higher taxonomic groups producing a much weaker relationship. Food webs with fewer unique and less weakly interacting species also show significantly greater variability in their levels of primary production. Thus, the loss of highly unique, weakly interacting species may eventually lead to dramatic state changes and unpredictable levels of ecosystem functioning.

Loss-of-function mutations in the cathepsin C gene result in periodontal disease and palmoplantar keratosis

Papillon-Lefevre syndrome, or keratosis palmoplantaris with periodontopathia (PLS, MIM 245000), is an autosomal recessive disorder that is mainly ascertained by dentists because of the severe periodontitis that afflicts patients(1,2). Both the deciduous and permanent dentitions are affected, resulting in premature tooth loss. Palmoplantar keratosis, varying from mild psoriasiform scaly skin to overt hyperkeratosis, typically develops within the first three years of life. Keratosis also affects other sites such as elbows and knees. Most PLS patients display both periodontitis and hyperkeratosis. some patients have only palmoplantar keratosis or periodontitis, and in rare individuals the periodontitis is mild and of late onset(3-6). The PLS locus has been mapped to chromosome 11q14-q21 (refs 7-9). Using homozygosity mapping in eight small consanguineous families, we have narrowed the candidate region to a 1.2-cM interval between D11S4082 and D11S931. The gene (CTSC) encoding the lysosomal protease cathepsin C (or dipeptidyl aminopeptidase I) lies within this interval. We defined the genomic structure of CTSC and found mutations in all eight families. In two of these families we used a functional assay to demonstrate an almost total loss of cathepsin C activity in PLS patients and reduced activity in obligate carriers.

A strategic review of electricity systems models

Electricity systems models are software tools used to manage electricity demand and the electricity systems, to trade electricity and for generation expansion planning purposes. Various portfolios and scenarios are modelled in order to compare the effects of decision making in policy and on business development plans in electricity systems so as to best advise governments and industry on the least cost economic and environmental approach to electricity supply, while maintaining a secure supply of sufficient quality electricity. The modelling techniques developed to study vertically integrated state monopolies are now applied in liberalised markets where the issues and constraints are more complex. This paper reviews the changing role of electricity systems modelling in a strategic manner, focussing on the modelling response to key developments, the move away from monopoly towards liberalised market regimes and the increasing complexity brought about by policy targets for renewable energy and emissions. The paper provides an overview of electricity systems modelling techniques, discusses a number of key proprietary electricity systems models used in the USA and Europe and provides an information resource to the electricity analyst not currently readily available in the literature on the choice of model to investigate different aspects of the electricity system.