Abstract: Cutaneous monostome trematode Collyriclum faba (Bremser in Schmalz 1831)
is a digenetic flatworm with unknown life cycle. Here, we provide the first
compelling evidence that despite low prevalence of the parasite, European
hirundines are parasitized by this species. First host record for sand martin
(Riparia riparia) and first European host record for barn swallow (Hirundo
rustica) is provided. The birds were captured and checked in ten European and
Middle Eastern countries, stretching from Ireland to Bahrain, but only samples
from Central Europe (Czech Republic, Hungary and Poland) were positive for
C. faba. In total, 164,582 sand martins and 100,443 barn swallows were
examined, and seven and two birds had cutaneous C. faba cysts. Even though
over 40% of the birds captured were juveniles, all but one infected individuals
were adults, equally both males and females. The prevalence of the parasite on
Central European hirundines were calculated as one in 20,641 for sand martins
and one in 4,484 for barn swallows. All the infected birds were captured in close
vicinity of water bodies. All the cysts were found close to the vent or on the legs.
No adverse effects on its bird hosts were observed.
Abstract: Nest attentiveness during the night is significantly lower in males but varies with the activities
of the breeding cycle. Male nest attentiveness shows minima during the burrowing and egg-laying phases,
and also during the brooding of chicks in second or re-nest broods.
Abstract: This letter reflects the previously published J.Chem.Inf.Model. paper dealing with science productivity in China, U.S.A., Germany, and Japan. It is shown how inappropriate use of Web of Knowledge (WoK) generates false positive data, dramatic increases in number of papers published, and may lead to unintentional exclusion of significant datasets from the evaluation. In its recent form, WoK is found to be biased when using âaddressâ field until year 1973, and âtopicâ field until year 1991.
Abstract: An increasing number of national and international funding and statistical agencies utilize Web of Science (WOS) as a source of data influencing their decisions and analyses of research outcome. However, currently existing data sources for scientometric research, including WOS, are far from being perfect. Most of the imperfections are caused by uneven coverage, errors or changes in indexing policies, or mistaken or ineffective retrieval strategies employed by the users. Thus, it is important to be aware of the critical elements of scientometric evaluation, as inappropriately designed search procedures may lead to confusing or false-positive results. This paper presents the analysis of a series of previously published papers, which were affected by errors of omission and commission due to changes in WOS abstracting policies. When comparing WOS Topic search with WOS Title search, substantial differences arose. Number of papers published every year on cruciate ligament was shown to remain unchanged since early 1980s, when employing WOS Title search. Similarly, trends in number of citations on this topics remain unchanged through the long period of time, reflecting only increasing amount of citable papers available. The findings differ from those reported previously based on WOS Topic search, as improvement in the search protocol fully explained and rejected the previously reported steep increase in publications on cruciate ligament, air pollution, and oral lesions since 1991. The different outcomes compared to the other search protocols were caused by variations in WOS abstracting policies, such as exclusion of the address field, keywords, and exclusion or changes of the country codes or names. Despite the percentage of WOS records lacking these fields is decreasing in time, inclusion of such records hinders the ability to use the respective fields in any long-term searches using the WOS database. The results suggest that WOS Topic search is not the appropriate tool to search for time-dependent changes in publication productivity.
Abstract:
Malignant melanoma is an aggressive cancer of pigment-producing cells, derivates of the neural crest. Surgical resection is the most effective form of treatment during initial phases of the disease. Advanced stages are usually treated by adjuvant immunotherapy (interferon α) or
dacarbazine + multiferon. Response and survival rates are extremely poor. The emerging approach of personalized medicine brings about significant advances in the treatment of melanoma. Apart from administration of imatinib for a small subgroup of melanomas harbouring KIT mutations, the most promising approach is the use of B-RAF kinase inhibitors. The previously tested RAF inhibitors (e. g. sorafenib) did not perform
better compared to conventional chemotherapy or immunotherapy. However, the results are much more promising with the recently developed
inhibitor PLX4032 (Plexxikon; RG7204, Roche Pharmaceuticals; vemurafenib). This inhibitor targets tumours harbouring B-RAF
V600E
of B-RAF
V600K
activating mutations, which are present in 40â70% of malignant melanomas. An absence of the above mentioned activating mutations or
parallel presence of activating RAS mutations (e. g. RAS
G12D
) should be used as contraindications. The use of PLX4032 provides better outcome
than any of the currently used therapies, including partial or complete response recorded in 81% of patients, and prolonged median survival.
Currently, this drug is being tested in phase II and III trials. The incidence of PLX4032-related adverse effects is relatively high; acquired resistance repeatedly occurring within several months of treatment may also represent a significant problem. Combined therapy is probably needed
to further increase the complete response rate and to prolong survival. This should either include some of the currently used chemotherapeutics, or alternatively it may employ inhibitors of some of the kinases capable of stimulating the MEK and ERK kinases independently of B-RAF
(e. g. COT). Nevertheless, even PLX4032 monotherapy should be viewed as a significant improvement of the current state-of-the-art treatment
of malignant melanoma
Abstract: Even though lung cancer incidence began to decline in the majority of industrialized countries, is still belong to cancers with one of the highest incidence and mortality rates. In the Czech Republic, epidermal growth factor receptor (EGFR) kinase activity inhibitors erlotinib and gefitinib are approved for the use as the second- and third-line treatment of non-small-cell lung cancer. In a cohort of non-small-cell lung cancer patients, erlotinib administration led to tumour regression in less than 20% of patients. However, when used in patients with EGFR-activating mutations, e.g. L858R or delE746-A750, the response rate increased to 75-82% in several parallel clinical studies. Similarly, improved response rate was reported in patients bearing amplified wild-type EGFR gene. In contrary, patients with T790M, D761Y, L747S, and T854A mutations (and some other rare abberations) were found to be resistant to treatment with small-molecule inhibitors targeting the active site of the kinase domain. These mutations do not change the EGFR affinity to gefitinib or erlotinib but the mutated receptor is able to bind ATP into its active site even in the presence of erlotinib or gefitinib, similar to a wild-type receptor without an inhibitor. Besides that, when the EGFR molecule bears both the activating (e.g. L858R) and resistance-inducing mutation (e.g. T790M), the tumour acquires resistance to both erlotinib and gefitinib treatment. Currently, research focuses on a development of new strategies that would allow treatment of patients bearing mutations inducing resistance to the small-molecule inhibitors targeted on the active site of EGFR kinase domain. Contrary to the current guidelines for Czech oncologists, identification of EGFR with any of the above mentioned resistance-inducing somatic mutations should be considered as an explicit contraindication for non-small-cell cancer treatment using small-molecule EGFR kinase activity inhibitors erlotinib or gefitinib. This should also include patients in whom a resistance-inducing mutation is detected together with any of the activating mutations or deletions.
Abstract: Signal transduction pathways play crucial role in number of cellular processes including proliferation, differentiation, adhesion, apoptosis, and metabolic homeostasis. Among the major regulatory mechanisms controlling signal transduction is reversible phosphorylation, which employs multiple kinases and phosphatases. Contrary to kinases, which are now among classic therapeutic targets of carcinogenesis regulation, the field of phosphatase research is still young and the roles of individual phosphatases are only recently recognized in detail.
Here we focus on novel aspects of signalling, detection, and targeting of both protein serine/threonine (PPs) and tyrosine (PTPs) phosphatases. The research on PPs is somewhat more advanced since the first discoveries of PPs in mid-60th years [1], whereas identification of the first genuine PTP was reported only as late as in 1988 by Nicholas Tonks and his colleagues [2]. The structures and functions of many PPs and PTPs and their mechanisms of regulation have already been defined. Some are specific for a particular substrate, while others are capable to dephosphorylate vast array of cellular proteins [3]. But only recently, the PPs and PTPs are recognized as not less important components of the same pathways that involve tyrosine or serine/threonine kinases. Even though we are still plagued by the problems of specificity and selectivity, the field significantly advanced forward and the PPs and PTPs holds much promise as future targets of anti-cancer agents. Here we focus on various areas of phosphatase research, which already uncovered findings with potential to improve patient care in terms of improved cancer diagnosis, prognosis, and treatment.
Abstract: The earliest known biochemical step that occurs after ligand binding to the multichain immune recognition receptor is tyrosine phosphorylation of the receptor subunits. In mast cells and basophils activated by multivalent antigen-IgE complexes, this step is mediated by Src family kinase Lyn, which phosphorylates the high affinity IgE receptor (Fc epsilon RI). However, the exact molecular mechanism of this phosphorylation step is incompletely understood. In this study, we tested the hypothesis that changes in activity and/ or topography of protein-tyrosine phosphatases (PTPs) could play a major role in the Fc epsilon RI triggering. We found that exposure of rat basophilic leukemia cells or mouse bone marrow-derived mast cells to PTP inhibitors, H2O2 or pervanadate, induced phosphorylation of the Fc epsilon RI subunits, similarly as Fc epsilon RI triggering. Interestingly, and in sharp contrast to antigen-induced activation, neither H2O2 nor pervanadate induced any changes in the association of Fc epsilon RI with detergent-resistant membranes and in the topography of Fc epsilon RI detectable by electron microscopy on isolated plasma membrane sheets. In cells stimulated with pervanadate, H2O2 or antigen, enhanced oxidation of active site cysteine of several PTPs was detected. Unexpectedly, most of oxidized phosphatases bound to the plasma membrane were associated with the actin cytoskeleton. Several PTPs (SHP-1, SHP-2, hematopoietic PTP, and PTP-MEG2) showed changes in their enzymatic activity and/or oxidation state during activation. Based on these and other data, we propose that down-regulation of enzymatic activity of PTPs and/or changes in their accessibility to the substrates play a key role in initial tyrosine phosphorylation of the Fc epsilon RI and other multichain immune receptors.
Abstract: Protein tyrosine phosphatases (PTPs) are considered to be involved in the etiology of diabetes mellitus, neural diseases such as Alzheimer's and Parkinson's disease, regulation of allergy and inflammation, or they are even considered to be responsible for the pathogens' virulence in vivo. Since discovery of first PTP inhibitors such as dephostatin in early 90th years, the research moved on toward search for inhibitors specific for the individual PTP molecules. Currently, dozens of new PTP inhibitors are reported each year, ranging from natural products, natural product analogs, peptides, phosphonates, nonpeptidic inhibitors, mimotopes, metal-containing inhibitors, redox inhibitors, to simply silencing RNAs as widely used inhibitors of PTP expression. Several currently used drugs also show PTP inhibitory activity. Among them are sodium stibogluconate, phenylarsine oxide, alendronate, etidronate, vanadate, gallium nitrate, suramin, or aplidin. However, the market is still waiting for the first clinically approved selective PTP inhibitor. Here in this review are described inhibitors of activity or expression of the particular classical PTPs, with emphasis on specific inhibition of the respective PTP over the others. The inhibitors are not classified according to their chemical composition, but according to their biological activity, which should help to simplify search for inhibitors of particular classical PTPs. Even though PTP inhibitors are difficult to develop, lifting the fog of phosphatase inhibition is of the great market potential and further clinical impact.
Abstract: Soil penetrability resistance was found to be crucial for nest site selection of all three Central European burrowing bird species-Sand Martins (Riparia riparia), European Bee-eaters (Merops apiaster), and Eurasian Kingfishers (Alcedo atthis). Soil penetrability resistance measurements were used to find out whether increased hardness of unexcavated banks is the key factor affecting the presence of burrowing birds. All three species avoided banks composed of too compact or too loose soils. Birds discriminated not only between high- and low-quality breeding banks, but also between different soil strata within banks. In banks with generally low penetrability resistance, Sand Martins preferred soil strata with the highest available penetrability resistance and compactness to avoid hole collapses. There was a preference for hard soil below holes to serve as a resistant platform when birds begin to dig their holes. In Sand Martins, the penetrability resistance level affected physical characteristics of holes such as tunnel length and dimensions of the orifices. Excessive compactness-and probably not high talus presence-was a major cause of abandonment of Sand Martin localities. A high penetrability resistance is the crucial factor for site selection in Sand Martins.
Abstract: The small chemical vacuolin-1 induces rapid formation of large vacuoles in various cell types. In epithelial cells, vacuolin-1 has been shown to inhibit Ca2+ ionophore-induced exocytosis depending on experimental conditions used but had no effect on repair of damaged membranes. However, it is not known whether vacuolin-1 could inhibit exocytosis induced by immunoreceptor triggering in professional secretory cells and whether there is any correlation between effect of vacuolin-1 on exocytosis and membrane repair in such cells. Here we show that in rat basophilic leukemia (RBL-2H3) cells activated by the high-affinity IgE receptor (Fc epsilon RI) triggering vacuolin-1 enhanced exocytosis. Under identical conditions of activation, vacuolin-1 inhibited exocytosis in mouse bone marrow-derived mast cells (BMMCs). This inhibition was not reflected by decreased phosphorylation of the Fc epsilon RI alpha and beta subunits, linker for activation of T cells, non-T cell activation linker, Akt and MAP kinase Erk, and uptake of extracellular Ca2+ indicating that early activation events are not affected. In both cell types vacuolin-1 led to formation of numerous vacuoles, a process which was inhibited by bafilomycin A1, an inhibitor of vacuolar H+-ATPase. Thapsigargin- or Call ionophore A23187-induced exocytosis also showed different sensitivity to the inhibitory effect of vacuolin-1. Pretreatment of the cells with vacuolin-1 followed by permeabilization with bacterial toxin streptolysin O enhanced Ca2+- dependent repair of plasma membrane lesions in RBL-2H3 cells but inhibited it in BMMCs. Our data indicate that lysosomal exocytosis exhibits different sensitivity to vacuolin-1 depending on the cell type analyzed and mode of activation. Furthermore, our results support the concept that lysosomal exocytosis is involved in the repair of injured plasma membranes. (C) 2009 Elsevier Inc. All rights reserved.
Abstract: Anafylactic reactions are mostly caused via the activation of the high affinity IgE receptor (FcεRI) on the surface of basophils and mast cells (classical pathway), or via the activation of the low affinity IgG receptor on the surface of macrophages (alternative pathway). Here we will focus on the classical pathway. Aggregation of FcεRI itself initiates signalization cascades involving tens of proteins, among the physiological effects are degranulation and histamine release. Frequently underscored is the possibility of activation of basophils via number of surface receptors (CD28, CD137, CD226, Toll-like receptors, and integrins, etc.) modulating intensity of signal induced by FcεRI aggregation. Some surface molecules (c-kit, Thy-1, C3a receptor, etc.) are even able to activate basophils in absence of the parallel FcεRI aggregation. In clinical or preclinical use is a number of inhibitors of unwanted activation of basophils during anaphylaxis. Among them are inhibitors of tyrosine kinases â Gleevec, dasatinib, or semaxinib. Promising are also humanized monoclonal antibodies, fusion proteins and above all the epitope-specific peptides called mimotopes.
Abstract: Status and population trends of sand martins (Riparia riparia) were studied over a fourteen year period in the Czech Republic. In sum, 438 occupied localites were found. The population fell off 83.2 % between years 1993 and 2005, which was unexpected as the population was stable or slightly increasing for years before. Number of holes per locality triplicated from 130 in 1992 to 314 in 2005 as a result of change of quarrying methods. In all but two years more colonies were lost than were formed. Among the localities preferred were sandpits (63.6 %), gravelsandpits (5.3 %), slopes and claypits (3.7 % each). Only 3.0 % of colonies were in riverbanks. Average altitude of colonies was 313.5 m a.s.l. with maxima around 650 in a.s.l. Negative influence of water precipitation during the breeding season and positive effects of precipitation in Subsaharan regions are described.
Abstract: Interleukin 6 (IL-6) is a pleiotropic cytokine that mediates a variety of functions, including induction of the acute-phase response in hepatocytes. IL-6 initiates its action by binding to its cell surface receptor, followed by activation of Janus kinases and tyrosine phosphorylation of the signal transducer and transcription factor (STAT) 3. Although it has been suggested that cholesterol- and sphingolipid-enriched membrane domains, called lipid rafts, and caveolin are involved in this process, their roles in the earliest stages of IL-6-mediated signaling are far from being understood. Here we show that pretreatment of HepG2 hepatoma cells with methyl-beta-cyclodextrin (M beta CD), which removes cholesterol and destroys lipid rafts, inhibited tyrosine phosphorylation of STAT3 in IL-6-activated, but not PV-activated cells. Furthermore, when the cells were lysed under conditions preserving lipid rafts, no IL-6- or PV-induced phosphorylation of STAT3 was observed. Although most of the STAT3 was found in large M beta CD-resistant assemblies in both non-activated and IL-6-activated cells, its association with lipid rafts was weak or undetectable. The extent of IL-6-induced tyrosine phosphorylation of STAT3 was comparable in cells expressing low or high levels of caveolin. Similar STAT3 transducer complexes were observed in freshly isolated rat hepatocytes. The combined data suggest that STAT3 tyrosine phosphorylation occurs in preformed transducer complexes that can be activated in the absence of intact lipid rafts or caveolin. (C) 2007 Elsevier Inc. All rights reserved.
Abstract: Engagement of the Fc epsilon RI in mast cells and basophils leads to a rapid tyrosine phosphorylation of the transmembrane adaptors LAT (linker for activation of T cells) and NTAL (non-T cell activation linker, also called LAB or LAT2). NTAL regulates activation of mast cells by a mechanism, which is incompletely understood. Here we report properties of rat basophilic leukemia cells with enhanced or reduced NTAL expression. Overexpression of NTAL led to changes in cell morphology, enhanced formation of actin filaments and inhibition of the Fc epsilon RI-induced tyrosine phosphorylation of the Fc epsilon RI subunits, Syk kinase and LAT and all downstream activation events, including calcium and secretory responses. In contrast, reduced expression of NTAL had little effect on early Fc epsilon RI-induced signaling events but inhibited calcium mobilization and secretory response. Calcium response was also repressed in Ag-activated cells defective in Grb2, a major target of phosphorylated NTAL. Unexpectedly, in cells stimulated with thapsigargin, an inhibitor of the endoplasmic reticulum Ca2(+) ATPase, the amount of cellular NTAL directly correlated with the uptake of extracellular calcium even though no enhanced tyrosine phosphorylation of NTAL was observed. The combined data indicate that NTAL regulates Fc epsilon RI-mediated signaling at multiple steps and by different mechanisms. At early stages NTAL interferes with tyrosine phosphorylation of several substrates and formation of signaling assemblies, whereas at later stages it regulates the activity of store-operated calcium channels through a distinct mechanism independent of enhanced NTAL tyrosine phosphorylation.
Abstract: Immunolabeling of isolated plasma membrane (PM) sheets combined with high-resolution electron microscopy is a powerful technique for understanding the topography of PM-bound signaling molecules. However, this technique has been mostly confined to analysis of membrane sheets from adherent cells. Here we present a rapid, simple and versatile method for isolation of PM sheets from non-adherent cells, and show its use for examination of the topography of Fee receptor I (Fc epsilon RI) and transmembrane adaptors, LAT (linker for activation of T cells) and NTAL (non-T cell activation linker), in murine bone marrow-derived mast cells (BMMC). The data were compared with those obtained from widely used but tumor-derived rat basophilic leukemia (RBL) cells. In non-activated cells, Fc epsilon RI was distributed either individually or in small Clusters of comparable size in both cell types. In multivalent antigen-activated BMMC as well as RBL cells, Fc epsilon RI was internalized to a similar extent, but, strikingly, internalization in BMMC was not preceded by formation of large (similar to 200 nm) aggregates of Fc epsilon RI, described previously in activated RBL cells. On the other hand, downstream adaptor proteins, LAT and NTAL, were localized in independent domains in both BMMC and RBL cells before and after Fc epsilon RI triggering. The combined data demonstrate unexpected properties of Fc epsilon RI signaling assemblies in BMMC and emphasize the importance of studies of PM sheets isolated from non-tumor cells. (C) 2007 Elsevier B.V. All rights reserved.
Abstract: Thy-1 (CD90) is a glycoprotein bound to the plasma membrane by a GPI anchor. Aggregation of Thy-1 in mast cells and basophils induces activation events independent of the expression of Fc epsilon receptor I (Fc epsilon RI). Although we and others have previously suggested that plasma membrane microdomains called lipid rafts are implicated in both Thy-1 and Fc epsilon RI signaling, properties of these microdomains are still poorly understood. In this study we used rat basophilic leukemia cells and their transfectants expressing both endogenous Thy-1.1 and exogenous Thy-1.2 genes and analyzed topography of the Thy-1 isoforms and Thy-l-induced signaling events. Light microscopy showed that both Thy-1 isoforms were in the plasma membrane distributed randomly and independently. Electron microscopy on isolated membrane sheets and fluorescence resonance energy transfer analysis indicated cross-talk between Thy-1 isoforms and between Thy-1 and Fc epsilon RI. This cross-talk was dependent on actin filaments. Thy-1 aggregates colocalized with two transmembrane adaptor proteins, non-T cell activation linker (NTAL) and linker for activation of T cells (LAT), which had been shown to inhabit different membrane microdomains. Thy-1 aggregation led to tyrosine phosphorylation of these two adaptors. The combined data indicate that aggregated GPI-anchored proteins can attract different membrane proteins in different clusters and thus can trigger different signaling pathways.
Abstract: Variability of the nest construction in swallows (Hirundinidae) is more diverse than in other families of oscine birds. I compared the nest-building behaviour with pooled data of clutch size and overall hatching success for 20 species of swallows. The clutch size was significantly higher in temperate cavity-adopting swallow species than in species using other nesting modes including species breeding in evolutionarily advanced mud nests (P < 0.05) except of the burrow-excavating Bank Swallow. Decrease of the clutch size during the evolution of nest construction is not compensated by the increase of the overall hatching success.
Abstract: During years 1992-2005, we performed a systematic search for the presence of sand martin colonies throughout the Czech Republic. Here we show a list of all sand martin nesting localities found, together with all available literature sources related to the area of the Czech Republic. Breeding of sand martins was confirmed in 66 out of 76 districts of the Czech Republic at 427 localities occupied since 1992 (Fig. 1) and another 313 localities occupied earlier in the 19th or 20th century. The combined data should serve as a comparative material necessary during the process of creating new protected areas aimed to allow sustainable existence of the sand martin population in the Czech Republic, as sand martins are strictly dependent on the mining activities almost all native nesting places were destroyed in the last decades by regulation of river banks.
Abstract: Activation of mast cells and basophils is accompanied by the production of reactive oxygen and nitrogen species that regulate diverse signaling pathways leading to the release of inflammatory mediators and production of a variety of cytokines. Although the functional pathways of reactive oxygen and nitrogen species in vivo are not completely understood, some novel metabolic pathways can be envisioned based on recent findings that protein tyrosine phosphatases can be regulated by reversible oxidation. In this review, we describe major sources and targets of reactive oxide and nitrogen species in mast cells and basophils. Direct and indirect regulations of class I and II Cys-based protein tyrosine phosphatases (LMW-PTP, PTEN, PTP-PEST, SHP-2, PTP1B, PTP alpha, PTP epsilon, DEP-1, TC45, SHP-1, HePTP and LAR) are discussed. The combined data highlight the role of redox-regulated protein tyrosine phosphatases as targets in the development of new ways of therapeutic intervention in allergies and inflammatory diseases.
Abstract: Previous studies using cytochalasins and latrunculin B, inhibitors of actin polymerization, showed that filamentous (F)-actin had a negative regulatory role in Fcepsilon receptor I (FcepsilonRI) signaling. How F-actin is involved in regulating the activation of mast cells is unknown. In this study we investigated the role of F-actin in mast cell activation induced by aggregation of the glycosylphosphatidylinositol (GPI)-anchored proteins Thy-1 and TEC-21, and compared it to activation via FcepsilonRI. Pretreatment of rat basophilic leukemia cells with latrunculin B inhibited the Thy-1-induced actin polymerization and elevated the Thy-1-mediated secretory and calcium responses. Inhibition of actin polymerization followed by Thy-1 aggregation resulted in an increased tyrosine phosphorylation of Syk, phospholipase Cgamma (PLCgamma), Gab2 and linker for activation of T cells (LAT) adapters, and some other signaling molecules. Enzymatic activities of phosphatidylinositol 3-kinase, PLCgamma, and phosphatase SHP-2 were also upregulated, but tyrosine phosphorylation of ezrin was inhibited. Similar changes were observed in FcepsilonRI-activated cells. Significant changes in intracellular distribution, tyrosine phosphorylation, and/or enzymatic activities of signaling molecules occurred in latrunculin-pretreated cells before cell triggering. The combined data suggest that actin polymerization is critical for setting the thresholds for mast cell signaling via aggregation of both FcepsilonRI and GPI-anchored proteins.
Abstract: The European bee-eater (Merops apiaster) is the first known species of the order Coracifformes and the second bird species whose distribution depends on the granulometrical characteristics of soils constituting suitable banks for breeding. The mean particle size of soil samples from bee-eater nest places was 42.76 +/- 13.58 mum (max 66.82 mum, min 20.10 mum). Mean particle size differed significantly between samples from bee-eater and sand martin nest places, and unoccupied cliffs respectively. In total 12 different particle sizes were analysed. There were no bee-eater holes in soils containing particles over 10,000 mum. The number of all psephitic particles (above 2,346 mum) was more than 15 times lower in samples from bee-eater colonies than in those from sand martin holes. However, samples from bee-eater colonies contained 20 times more soil grains between 28.0 and 9.2 mum. These highly significant differences may explain why these two species do not usually breed in mixed colonies.
Abstract: The first granulometrical analysis of soil samples from nesting banks of the Eurasian Kingfisher (Alcedo atthis) is reported. In total 29 samples from 22 banks located in the Czech Republic were analysed using the dry sieve analysis and decantation. Twelve standardized particle size fractions were determined in all groups of samples. Mean particle size of soil samples from banks occupied by Kingfishers averaged 991 +/- 1747 mu m, the variability of the content of particular soil particle fraction is higher than previously published on Sand Martins and Bee-Eaters. The results suggest that the presence/absence of some particle size fractions in extreme values is decisive for the presence/absence of Kingfishers in each appropriate nesting bank. Among banks unoccupied by Kingfishers were those with soil particles above 40,000 mu m, or with the content of particle size fractions 2,346-774 mu m below 5%. Kingfishers do not occupy banks with the content of the fraction 9.2-3.0 mu m higher than 2.156%, or with the content of the particle size fraction 3.0-1.0 higher than 0.415%, too. Soils composed from grains exceeding any of these values are expected to be unoccupied by the Eurasian Kingfisher.
Abstract: Engagement of the Fcepsilon receptor I (FcepsilonPI) on mast cells and basophils initiates signaling pathways leading to degranulation. Early activation events include tyrosine phosphorylation of two transmembrane adaptor proteins, linker for activation of T cells (LAT) and non-T cell activation linker (NTAL; also called LAB; a product of Wbscr5 gene). Previous studies showed that the secretory response was partially inhibited in bone marrow-derived mast cells (BMMCs) from LAT-deficient mice. To clarify the role of NTAL in mast cell degranulation, we compared FcepsilonRI-mediated signaling events in BMMCs from NTAL-deficient and wild-type mice. Although NTAL is structurally similar to LAT, antigen-mediated degranulation responses were unexpectedly increased in NTAL-deficient mast cells. The earliest event affected was enhanced tyrosine phosphorylation of LAT in antigen-activated cells. This was accompanied by enhanced tyrosine phosphorylation and enzymatic activity of phospholipase C gamma1 and phospholipase C gamma2, resulting in elevated levels of inositol 1,4,5-trisphosphate and free intracellular Ca2+. NTAL-deficient BMMCs also exhibited an enhanced activity of phosphatidylinositol 3-OH kinase and Src homology 2 domain-containing protein tyrosine phosphatase-2. Although both LAT and NTAL are considered to be localized in membrane rafts, immunogold electron microscopy on isolated membrane sheets demonstrated their independent clustering. The combined data show that NTAL is functionally and topographically different from LAT.
Abstract: The importance of correlations between soil particle composition and the physical characteristics of Sand Martin Riparia riparia breeding holes has received very little attention. I used dry sieve analysis and decantation to examine 14 particle size ranges of samples from 654 breeding holes collected at 106 breeding colonies in the Czech Republic and at three in Great Britain. All five measured physical characteristics (tunnel depth, width and height of the entrance opening, slope of the tunnel and the distance to the bank top) were significantly correlated with measured soil particle size ranges. Tunnel depth, which is one of the most important factors influencing breeding success in this species, increased as the proportion of small particles (<900 μm) in the soil increased.
Abstract: Protein tyrosine and lipid phosphorylations are early and critical events in type 1 Fcepsilon receptor (FcepsilonRI)-mediated activation of mast cells and basophils. Tyrosine phosphorylation of FcepsilonRI subunits as well as other signal transduction molecules reflects the balance between the action of protein tyrosine kinases and phosphatases. Similarly, the phosphate content of inositol phospholipids, involved in the recruitment of signalling molecules to the plasma membrane and the generation of secondary messengers, is the net result of the opposing effects of phosphoinositide kinases and lipid phosphatases. This review summarizes the current understanding of the structural and functional aspects of nonreceptor protein tyrosine phosphatases (SHP-1, SHP-2, HePTP, PTP20, PRL1, PRL2, PTP-MEG1 and PTP-MEG2) and lipid phosphatases (SHIP and SHIP2) in the activation of mast cells and basophils after FcepsilonRI aggregation. New approaches towards a deeper understanding of the role of phosphatases in mast cell physiology are also discussed. Copyright (C) 2002 S. Karger AG, Basel.
Abstract: Granulometric analysis was performed on 1,652 sand samples over 0.9 mm (megapsephitic, psephitic and psamitic fractions of sand and gravel) collected from 82 nesting sites of bank swallows (Riparia riparia) in the Czech Republic, Germany, and Great Britain. Most samples were collected from burrows, or above and below them. Bank swallows nested only in sand with grains up to 60 mm (99.8%, the one exception destroyed by rainfall). The mean percentage structure of sand from burrows was: < 0.9 mm 59.26%, 0.9-1.25 mm 8.27%, 1.25-2 mm 2.82%, 2-3 mm 13.19%, 3-4 mm 8.00%, 4-10 mm 7.53%; and 10-60 mm 0.92%. Differences between samples collected from burrows and from sites around burrows on colonized faces were significant in all cases. It was found out that bank swallows selected nest sites based upon the size of grains composing the bank (determined through the building of new nestwalls).
