Atmospheric nitrogen deposition is associated with elevated phosphorus limitation of lake zooplankton

Here, we present data that for the first time suggests that the effects of atmospheric nitrogen (N) deposition on nutrient limitation extend into the food web. We used a novel and sensitive assay for an enzyme that is over‐expressed in animals growing under dietary phosphorus (P) deficiency (alkaline phosphatase activity, APA) to assess the nutritional status of major crustacean zooplankton taxa in lakes across a gradient of atmospheric N deposition in Norway. Lakes receiving high N deposition had suspended organic matter (seston) with significantly elevated carbon:P and N:P ratios, indicative of amplified phytoplankton P limitation. This P limitation appeared to be transferred up the food chain, as the cosmopolitan seston‐feeding zooplankton taxa Daphnia and Holopedium had significantly increased APA. These results indicate that N deposition can impair the efficiency of trophic interactions by accentuating stoichiometric food quality constraints in lake food webs.     

Cases with manifestation of <Emphasis Type="Italic">chemodectoma</Emphasis> diagnosed in dogs in Department of Internal Diseases with Horses,Dogs and Cats Clinic,Veterinary Medicine Faculty,University of Environmental and Life Sciences,Wroclaw, Poland

In the period of 3 years, 9 tumours of chemodectoma were supravitally diagnosed and histopathologically verified in dogs. In this period 15 351 dogs were admitted to the Clinic of Dogs and Cats and 2 145 dogs were examined in the cardiological outpatient clinic for dogs. This tumour is located in a typical place - at the base of the heart. Most frequently the tumour manifested in older boxers. Only in one case such a tumour was diagnosed in another breed of dogs. The tumours ranged in size between 3 and 16 cm in diameter. The principal sign accompanying tumours of cardiac base involved dyspnoea but in 3 cases the tumours yielded no clinical signs. All the diagnoses were additionally verified using immunohistochemical examination. We used antibodies to chromogranin A (clone DAK-A3 1:100), synaptophysin (clone SY38 1:20) and neuron-specific enolase (clone BBS/NC/VI-H14 1:150). An immunohistochemical examination is vital for the diagnosis since it allows to differentiate histologically distinct types of neoplasia which may locate in the same site and may manifest a similar histological pattern.     

The PluriNetWork: an electronic representation of the network underlying pluripotency in mouse, and its applications

Background

Analysis of the mechanisms underlying pluripotency and reprogramming would benefit substantially from easy access to an electronic network of genes, proteins and mechanisms. Moreover, interpreting gene expression data needs to move beyond just the identification of the up-/downregulation of key genes and of overrepresented processes and pathways, towards clarifying the essential effects of the experiment in molecular terms.

Methodology/Principal Findings

We have assembled a network of 574 molecular interactions, stimulations and inhibitions, based on a collection of research data from 177 publications until June 2010, involving 274 mouse genes/proteins, all in a standard electronic format, enabling analyses by readily available software such as Cytoscape and its plugins. The network includes the core circuit of Oct4 (Pou5f1), Sox2 and Nanog, its periphery (such as Stat3, Klf4, Esrrb, and c-Myc), connections to upstream signaling pathways (such as Activin, WNT, FGF, BMP, Insulin, Notch and LIF), and epigenetic regulators as well as some other relevant genes/proteins, such as proteins involved in nuclear import/export. We describe the general properties of the network, as well as a Gene Ontology analysis of the genes included. We use several expression data sets to condense the network to a set of network links that are affected in the course of an experiment, yielding hypotheses about the underlying mechanisms.

Conclusions/Significance

We have initiated an electronic data repository that will be useful to understand pluripotency and to facilitate the interpretation of high-throughput data. To keep up with the growth of knowledge on the fundamental processes of pluripotency and reprogramming, we suggest to combine Wiki and social networking software towards a community curation system that is easy to use and flexible, and tailored to provide a benefit for the scientist, and to improve communication and exchange of research results. A PluriNetWork tutorial is available at http://www.ibima.med.uni-rostock.de/IBIMA/PluriNetWork/.     

Quantum chemical studies on substitution effects within silyl group in the silylative coupling of olefins

In this study quantum chemical calculations based on the density functional theory (DFT) have been carried out to examine the effects of methoxy substituent attached to a silicon atom on the reaction of silylative coupling of olefins. It has been shown, that substituted substrate undergoes the reaction according to the recently proposed insertion-rotation-elimination mechanism. During the rotation around C-C single bond additional stabilization by oxygen-ruthenium interaction was observed. Similarly to the (trimethylsilyl)ethene the rate determining step of the reaction is the insertion of the alkene into Ru-Si single bond. The substitution of SiMe₃ by Si(OMe)₃ decreases the energy span of the reaction by almost 3 kcal mol^-1 that is from 21 kcal mol^-1 to 18 kcal mol^-1. The decrease of the energy barrier of the reaction seems to be the result of the increase of point charge differences between the Ru and Si atoms which increases electrostatic attraction between these atoms. Moreover, for Si(OMe)₃ the rate-determining transition state is closer to the alkene interacting with the Ru centre side of the reaction.     

Prognostic and predictive significance of p53, EGFr,Ki-67 in larynx preservation treatment

Background

The optimal management of advanced laryngeal and hypopharyngeal cancers (L&HC) must involve consideration of both survival and functional effect of the given treatment approach. Despite over two decades of investigations of several treatment options, including surgery, radiotherapy, chemotherapy or some combinations thereof, little consensus exists as to which treatment offers the best survival, together with functional speech and swallowing.

Aim

To determine predictive and prognostic value of p53, EGFr, Ki-67 in patients with advanced laryngeal and hypopharyngeal cancer, treated with larynx preservation intent.

Materials and methods

Thirty-three patients received 2–3 cycles of induction chemotherapy (ICHT) consisting of cisplatin and fluoruracil and underwent subsequent radical radiotherapy. Immunohistochemical analyzes of p53, EGFr and Ki-67 were performed.

Results

Response to ICHT was obtained in 24 patients (75%). Better response to ICHT was correlated only with EGFr expression (p = 0.04, RR = 1.91). The 5-year loco-regional control (LRC) and disease-specific survival (DSS) rates were 48% and 57%, respectively. The 5-year larynx preservation rate was 68% in responders to ICHT compared to 21% in non-responders (p = 0.02). It was also higher in patients without EGFr expression (but not significantly, p = 0.43).

Conclusion

Lack of EGFr expression is a favorable predictive factor for response to ICHT. Neither p53 nor Ki-67 have predictive and prognostic value in larynx preservation treatment.     

Structure and expression of conserved Wnt pathway components in the demosponge Amphimedon queenslandica

Wnt-signalling plays a critical role in animal development, and its misregulation results in serious human diseases, including cancer. While the Wnt pathway is well studied in eumetazoan models, little is known about the evolutionary origin of its components and their functions. Here, we have identified key machinery of the Wnt-β-catenin (canonical)-signalling pathway that is encoded in the Amphimedon queenslandica (Demospongiae; Porifera) genome, namely Wnt, Fzd, SFRP, Lrp5/6, Dvl, Axin, APC, GSK3, β-catenin, Tcf, and Groucho. Most of these genes are not detected in the choanoflagellate and other nonmetazoan eukaryotic genomes. In contrast, orthologues of some of key components of bilaterian Wnt-planar cell polarity and Wnt/Ca(2+) are absent from the Amphimedon genome, suggesting these pathways evolved after demosponge and eumetazoan lineages diverged. Sequence analysis of the identified proteins of the Wnt-β-catenin pathway has revealed the presence of most of the conserved motifs and domains responsible for protein-protein and protein-DNA interactions in vertebrates and insects. However, several protein-protein interaction domains appear to be absent from the Amphimedon Axin and APC proteins. These are also missing from their orthologues in the cnidarian Nematostella vectensis, suggesting that they are bilaterian novelties. All of the analyzed Wnt pathway genes are expressed in specific patterns during Amphimedon embryogenesis. Most are expressed in especially striking and highly dynamic patterns during formation of a simple organ-like larval structure, the pigment ring. Overall, our results indicate that the Wnt-β-catenin pathway was used in embryonic patterning in the last common ancestor of living metazoans. Subsequently, gene duplications and a possible increase in complexity of protein interactions have resulted in the precisely regulated Wnt pathway observed in extant bilaterian animals.     

Acanthamoeba castellanii: In vitro effects of selected biological, physical and chemical factors

Trophozoites and cysts of free-living Acanthamoeba castellanii present a serious risk to human health as causative agents of human diseases such as fatal granulomatous amoebic encephalitis and Acanthamoeba keratitis that is reported from various part of the world, also in Poland, with increasing frequency, particularly in the contact lens wearers. The amphizoic amoebae are generally extremely resistant to different chemical agents, however, several strains/isolates within A. castellanii may differ in virulence. Among the features considered as associated with the amoeba pathogenicity, temperature tolerance and resistance to different environmental conditions are reported. In the present study, A. castellanii strain cultured in 26 °C after several year passages were tested for sensibility/tolerance to instant temperature changes as well as exposition to deuterium oxide, D₂O. Significant decrease of number of viable amoebae during in vitro exposition to D₂O occurred, but no changes in trophozoites/cysts ratio. The ability of the strain examined to develop in higher temperature may indicate a wide adaptation reserve and its pathogenic potential.