First Measurement of Transferred Polarization in the Exclusive e p --> e' K+ Lambda Reaction

The first measurements of the transferred polarization for the exclusive ep --> e'K+ Lambda reaction have been performed in Hall B at the Thomas Jefferson National Accelerator Facility using the CLAS spectrometer. A 2.567 GeV electron beam was used to measure the hyperon polarization over a range of Q2 from 0.3 to 1.5 (GeV/c)2, W from 1.6 to 2.15 GeV, and over the full center-of-mass angular range of the K+ meson. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A non-relativistic quark model interpretation of our data suggests that the s-sbar quark pair is produced with spins predominantly anti-aligned. Implications for the validity of the widely used 3P0 quark-pair creation operator are discussed.Comment: 6 pages, 4 figure

Somatic VHL gene alterations in MEN2-associated medullary thyroid carcinoma

BACKGROUND: Germline mutations in RET are responsible for multiple endocrine neoplasia type 2 (MEN2), an autosomal dominantly inherited cancer syndrome that is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and parathyroid hyperplasia/adenoma. Recent studies suggest a "second hit" mechanism resulting in amplification of mutant RET. Somatic VHL gene alterations are implicated in the pathogenesis of MEN2 pheochromocytomas. We hypothesized that somatic VHL gene alterations are also important in the pathogenesis of MEN2-associated MTC. METHODS: We analyzed 6 MTCs and 1 C-cell hyperplasia (CCH) specimen from 7 patients with MEN2A and RET germline mutations in codons 609, 618, 620, or 634, using microdissection, microsatellite analysis, phosphorimage densitometry, and VHL mutation analysis. RESULTS: First, we searched for allelic imbalance between mutant and wild-type RET by using the polymorphic markers D10S677, D10S1239, and RET on thyroid tissue from these patients. Evidence for RET amplification by this technique could be demonstrated in 3 of 6 MTCs. We then performed LOH analysis using D3S1038 and D3S1110 which map to the VHL gene locus at 3p25/26. VHL gene deletion was present in 3 MTCs. These 3 MTCs also had an allelic imbalance between mutant and wild-type RET. Mutation analysis of the VHL gene showed a somatic frameshift mutation in 1 MTC that also demonstrated LOH at 3p25/26. In the 2 other MTCs with allelic imbalance of RET and somatic VHL gene deletion, no somatic VHL mutation could be detected. The CCH specimen did neither reveal RET imbalance nor somatic VHL gene alterations. CONCLUSION: These data suggest that a RET germline mutation is necessary for development of CCH, that allelic imbalance between mutant and wild-type RET may set off tumorigenesis, and that somatic VHL gene alterations may not play a major role in tumorigenesis of MEN2A-associated MTC

Influence of soil type and natural Zn chelates on flax response, tensile properties and soil Zn availability

A greenhouse experiment was conducted on weakly acidic and calcareous soils to evaluate the relative efficiencies of three natural Zn chelates [Zn-aminelignosulphonate (Zn-AML), Zn-polyhydroxyphenylcarboxylate (Zn-PHP) and Zn-S,S-ethylenediaminedisuccinate (Zn-S,S-EDDS)] applied to a crop textile flax (Linum ussitatisimum L.) at application rates of 0, 5 and 10 mg Zn kg−1. In the flax plant, the following parameters were determined: dry matter yield, soluble and total Zn concentrations in leaf and stem, chlorophyll, crude fibre, and tensile properties. For the different soil samples, the following parameters were determined: available Zn (DTPA-AB and Mehlich-3 extractable Zn), easily leachable Zn (BaCl2-extractable Zn), the distribution of Zn fractions, pH and redox potential. On the basis of the use of added Zn by flax, or Zn utilization, it would seem recommendable to apply Zn-S,S-EDDS at the low Zn rate in both soils. In contrast, adding the high Zn rate of this chelate to the weakly acidic soil produced an excessive Zn concentration in the plant, which caused a significant decrease in both dry matter yield and chlorophyll content. Furthermore, assessing available Zn with the DTPA-AB method proved the best way of estimating the level of excess Zn in flax plants. The soluble Zn concentration, which was established with 2-(N-morpholino)ethanesulfonic acid reagent (MES), of plant fresh and dry matter could be used as an alternative way of diagnosing the nutritional status of Zn in flax plants. In this experiment, the highest soil pHs were associated with the lowest redox potentials, which coincided with the smallest amounts of available Zn and water soluble Zn in soil, and the lowest levels of Zn uptake by flax plants

Background matching in the brown shrimp Crangon crangon : adaptive camouflage and behavioural-plasticity

A combination of burrowing behaviour and very efficient background matching makes the brown shrimp Crangon crangon almost invisible to potential predators and preys. This raises questions on how shrimp succeed in concealing themselves in the heterogeneous and dynamic estuarine habitats they inhabit and what type of environmental variables and behavioural factors affect their colour change abilities. Using a series of behavioural experiments, we show that the brown shrimp is capable of repeated fast colour adaptations (20% change in dark pigment cover within one hour) and that its background matching ability is mainly influenced by illumination and sediment colour. Novel insights are provided on the occurrence of non-adaptive (possibly stress) responses to background changes after long-time exposure to a constant background colour or during unfavourable conditions for burying. Shrimp showed high levels of intra- and inter-individual variation, demonstrating a complex balance between behavioural-plasticity and environmental adaptation. As such, the study of crustacean colour changes represents a valuable opportunity to investigate colour adaptations in dynamic habitats and can help us to identify the mayor environmental and behavioural factors influencing the evolution of animal background matching

A journey to Semantic Web query federation in the life sciences

Background: As interest in adopting the Semantic Web in the biomedical domain continues to grow, Semantic Web technology has been evolving and maturing. A variety of technological approaches including triplestore technologies, SPARQL endpoints, Linked Data, and Vocabulary of Interlinked Datasets have emerged in recent years. In addition to the data warehouse construction, these technological approaches can be used to support dynamic query federation. As a community effort, the BioRDF task force, within the Semantic Web for Health Care and Life Sciences Interest Group, is exploring how these emerging approaches can be utilized to execute distributed queries across different neuroscience data sources. Methods and results: We have created two health care and life science knowledge bases. We have explored a variety of Semantic Web approaches to describe, map, and dynamically query multiple datasets. We have demonstrated several federation approaches that integrate diverse types of information about neurons and receptors that play an important role in basic, clinical, and translational neuroscience research. Particularly, we have created a prototype receptor explorer which uses OWL mappings to provide an integrated list of receptors and executes individual queries against different SPARQL endpoints. We have also employed the AIDA Toolkit, which is directed at groups of knowledge workers who cooperatively search, annotate, interpret, and enrich large collections of heterogeneous documents from diverse locations. We have explored a tool called "FeDeRate", which enables a global SPARQL query to be decomposed into subqueries against the remote databases offering either SPARQL or SQL query interfaces. Finally, we have explored how to use the vocabulary of interlinked Datasets (voiD) to create metadata for describing datasets exposed as Linked Data URIs or SPARQL endpoints. Conclusion: We have demonstrated the use of a set of novel and state-of-the-art Semantic Web technologies in support of a neuroscience query federation scenario. We have identified both the strengths and weaknesses of these technologies. While Semantic Web offers a global data model including the use of Uniform Resource Identifiers (URI's), the proliferation of semantically-equivalent URI's hinders large scale data integration. Our work helps direct research and tool development, which will be of benefit to this community.Virtual Laboratory for e-Science program supported by BSIK grants from the Dutch Ministry of Education, Culture and ScienceJoint Information Systems Committee (JISC) for the FlyWeb ProjectKonrad Lorenz Institute for Evolution and Cognition Research, AustriaScience Foundation IrelandNational Institutes of Health (grants P01 DC04732 and U24 NS051869

Evidence for inbreeding depression and post-pollination selection against inbreeding in the dioecious plant Silene latifolia

In many species, inbred individuals have reduced fitness. In plants with limited pollen and seed dispersal, post-pollination selection may reduce biparental inbreeding, but knowledge on the prevalence and importance of pollen competition or post-pollination selection after non-self pollination is scarce. We tested whether post-pollination selection favours less related pollen donors and reduces inbreeding in the dioecious plant Silene latifolia. We crossed 20 plants with pollen from a sibling and an unrelated male, and with a mix of both. We found significant inbreeding depression on vegetative growth, age at first flowering and total fitness (22% in males and 14% in females). In mixed pollinations, the unrelated male sired on average 57% of the offspring. The greater the paternity share of the unrelated sire, the larger the difference in relatedness of the two males to the female. The effect of genetic similarity on paternity is consistent with predictions for post-pollination selection, although paternity, at least in some crosses, may be affected by additional factors. Our data show that in plant systems with inbreeding depression, such as S. latifolia, pollen or embryo selection after multiple-donor pollination may indeed reduce inbreeding