PECAM-1 expression and activity negatively regulate multiple platelet signaling pathways

Platelet endothelial cell adhesion molecule-1 (PECAM-1) inhibits platelet response to collagen and may also inhibit two other major platelet agonists ADP and thrombin although this has been less well explored. We hypothesized that the combined effect of inhibiting these three platelet activating pathways may act to significantly inhibit thrombus formation. We demonstrate a negative relationship between PECAM-1 surface expression and platelet response to cross-linked collagen related peptide (CRP-XL) and ADP, and an inhibitory effect of PECAM-1 clustering on platelet response to CRP-XL, ADP and thrombin. This combined inhibition of multiple signaling pathways results in a marked reduction in thrombus formation.     

Influence of clotting time on the protein composition of serum samples based on LC-MS data

Many large, disease-related biobanks of serum samples have been established prior to the widespread use of proteomics in biomarker research. These biobanks may contain relevant information about the disease process, response to therapy or patient classifications especially with respect to long-term follow-up that is otherwise very difficult to obtain based on newly initiated studies, particularly in the case of slowly developing diseases. An important parameter that may influence the composition of serum but that is often not exactly known is clotting time. We therefore investigated the influence of clotting time on the protein and peptide composition of serum by label-free and stable-isotope labeling techniques. The label-free analysis of trypsin-digested serum showed that the overall pattern of LC-MS data is not affected by clotting times varying from 2 to 8h. However, univariate and multivariate statistical analyses revealed that proteins that are directly involved in blood clot formation, such as the clotting-derived fibrinopeptides, change significantly. This is most easily detected in the supernatant of acid-precipitated, immunodepleted serum. Stable-isotope labeling techniques show that truncated or phosphorylated forms of fibrinopeptides A and B increase or decrease depending on clotting time. These patterns can be easily recognized and should be taken into consideration when analyzing LC-MS data using serum sample collections of which the clotting time is not known. Next to the fibrinopeptides, leucine-rich alpha-2-glycoprotein (P02750) was shown to be consistently decreased in samples with clotting times of more than 1h. For prospective studies, we recommend to let blood clot for at least 2h at room temperature using glass tubes with a separation gel and micronized silica to accelerate blood clotting.     

Complex nitrogen cycling in the sponge Geodia barretti

Marine sponges constitute major parts of coral reefs and deep‐water communities. They often harbour high amounts of phylogenetically and physiologically diverse microbes, which are so far poorly characterized. Many of these sponges regulate their internal oxygen concentration by modulating their ventilation behaviour providing a suitable habitat for both aerobic and anaerobic microbes. In the present study, both aerobic (nitrification) and anaerobic (denitrification, anammox) microbial processes of the nitrogen cycle were quantified in the sponge Geodia barretti and possible involved microbes were identified by molecular techniques. Nitrification rates of 566 nmol N cm^?3 sponge day^?1 were obtained when monitoring the production of nitrite and nitrate. In support of this finding, ammonia‐oxidizing Archaea (crenarchaeotes) were found by amplification of the amoA gene, and nitrite‐oxidizing bacteria of the genus Nitrospira were detected based on rRNA gene analyses. Incubation experiments with stable isotopes (¹⁵NO₃^‐ and ¹⁵NH₄⁺) revealed denitrification and anaerobic ammonium oxidation (anammox) rates of 92 nmol N cm^?3 sponge day^?1 and 3 nmol N cm^?3 sponge day^?1 respectively. Accordingly, sequences closely related to ‘Candidatus Scalindua sorokinii’ and ‘Candidatus Scalindua brodae’ were detected in 16S rRNA gene libraries. The amplification of the nirS gene revealed the presence of denitrifiers, likely belonging to the Betaproteobacteria. This is the first proof of anammox and denitrification in the same animal host, and the first proof of anammox and denitrification in sponges. The close and complex interactions of aerobic, anaerobic, autotrophic and heterotrophic microbial processes are fuelled by metabolic waste products of the sponge host, and enable efficient utilization and recirculation of nutrients within the sponge–microbe system. Since denitrification and anammox remove inorganic nitrogen from the environment, sponges may function as so far unrecognized nitrogen sinks in the ocean. In certain marine environments with high sponge cover, sponge‐mediated nitrogen mineralization processes might even be more important than sediment processes.     

Solar activity affects avian timing of reproduction

Avian timing of reproduction is strongly affected by ambient temperature. Here we show that there is an additional effect of sunspots on laying date, from five long-term population studies of great and blue tits (Parus major and Cyanistes caeruleus), demonstrating for the first time that solar activity not only has an effect on population numbers but that it also affects the timing of animal behaviour. This effect is statistically independent of ambient temperature. In years with few sunspots, birds initiate laying late while they are often early in years with many sunspots. The sunspot effect may be owing to a crucial difference between the method of temperature measurements by meteorological stations (in the shade) and the temperatures experienced by the birds. A better understanding of the impact of all the thermal components of weather on the phenology of ecosystems is essential when predicting their responses to climate change.     

Animal migration: linking models and data beyond taxonomic limits

An international workshop on animal migration was held at the Lorentz Center in Leiden, The Netherlands, 2–6 March 2009, bringing together leading theoreticians and empiricists from the major migratory taxa, aiming at the identification of cutting-edge questions in migration research that cross taxonomic borders.     

Early Assessment of Anxiety and Behavioral Response to Novel Swine-Origin Influenza A(H1N1)

Background

Since late April, 2009, a novel influenza virus A (H1N1), generally referred to as the “swine flu,” has spread around the globe and infected hundreds of thousands of people. During the first few days after the initial outbreak in Mexico, extensive media coverage together with a high degree of uncertainty about the transmissibility and mortality rate associated with the virus caused widespread concern in the population. The spread of an infectious disease can be strongly influenced by behavioral changes (e.g., social distancing) during the early phase of an epidemic, but data on risk perception and behavioral response to a novel virus is usually collected with a substantial delay or after an epidemic has run its course.

Methodology/Principal Findings

Here, we report the results from an online survey that gathered data (n = 6,249) about risk perception of the Influenza A(H1N1) outbreak during the first few days of widespread media coverage (April 28 - May 5, 2009). We find that after an initially high level of concern, levels of anxiety waned along with the perception of the virus as an immediate threat. Overall, our data provide evidence that emotional status mediates behavioral response. Intriguingly, principal component analysis revealed strong clustering of anxiety about swine flu, bird flu and terrorism. All three of these threats receive a great deal of media attention and their fundamental uncertainty is likely to generate an inordinate amount of fear vis-a-vis their actual threat.

Conclusions/Significance

Our results suggest that respondents'' behavior varies in predictable ways. Of particular interest, we find that affective variables, such as self-reported anxiety over the epidemic, mediate the likelihood that respondents will engage in protective behavior. Understanding how protective behavior such as social distancing varies and the specific factors that mediate it may help with the design of epidemic control strategies.     

Genetic variation of Mimetes hirtus and Mimetes fimbriifolius (Proteaceae) – a comparative analysis of two closely related fynbos species

We investigated the influence of differing life history traits on the genetic structure of the related species Mimetes fimbriifolius and Mimetes hirtus (Proteaceae), which occur in the South African fynbos. Both species are bird‐pollinated and ant‐dispersed, but differ in rarity, longevity, ecological strategy and the fragmentation of their distribution area. We used AFLPs to study genetic variation within and between 21 populations of these two species across their distribution range. AFLP analysis revealed significantly higher genetic variation within populations of M. fimbriifolius than within M. hirtus. While M. fimbriifolius clearly lacked any significant genetic differentiation between populations, a distinct geographic pattern was observed for M. hirtus. Differentiation was, however, stronger at the regional (Φ_PT = 0.57) than at the local scale (Φ_PT = 0.08). Our results clearly indicate that even closely related species that share the same mode of pollination and seed dispersal can differ in their genetic structure, depending on the magnitude of fragmentation, longevity of individuals and ecological strategy.     

GeneFISH – an in situ technique for linking gene presence and cell identity in environmental microorganisms

Our knowledge concerning the metabolic potentials of as yet to be cultured microorganisms has increased tremendously with the advance of sequencing technologies and the consequent discoveries of novel genes. On the other hand, it is often difficult to reliably assign a particular gene to a phylogenetic clade, because these sequences are usually found on genomic fragments that carry no direct marker of cell identity, such as rRNA genes. Therefore, the aim of the present study was to develop geneFISH – a protocol for linking gene presence with cell identity in environmental samples, the signals of which can be visualized at a single cell level. This protocol combines rRNA‐targeted catalysed reporter deposition – fluorescence in situ hybridization and in situ gene detection. To test the protocol, it was applied to seawater samples from the Benguela upwelling system. For gene detection, a polynucleotide probe mix was used, which was designed based on crenarchaeotal amoA clone libraries prepared from each seawater sample. Each probe in the mix was selected to bind to targets with up to 5% mismatches. To determine the hybridization parameters, the T_m of probes, targets and hybrids was estimated based on theoretical calculations and in vitro measurements. It was shown that at least 30%, but potentially the majority of the Crenarchaeota present in these samples harboured the amoA gene and were therefore likely to be catalysing the oxidation of ammonia.