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Different Stimuli (different + stimulus)
Selected AbstractsDifferent Stimuli Reduce Attraction to Pollinators in Male and Female Figs in the Dioecious Fig Ficus hispidaBIOTROPICA, Issue 6 2009Hao-Yuan Hu ABSTRACT Fig trees (Ficus) and their obligate pollinating wasps (Hymenoptera, Chalcidoidea, Agaonidae) are a classic example of a coevolved mutualism. Pollinating wasps are attracted to figs only when figs are receptive. It has been shown that figs will lose their attraction to pollinators sooner in monoecious and male dioecious figs when multiple pollinators have entered the enclosed inflorescence. However, little is known about the nature of the stimulus inducing the loss of attraction. By conducting experiments on the functionally dioecious fig, Ficus hispida, we show that (1) different stimuli induce the loss of attraction in each sex, pollination in female figs, and oviposition in male figs; and (2) foundress number affects the loss of attraction in both sexes only when the prerequisites (i.e., pollination in female figs and oviposition in male figs) have been satisfied. In general, the more foundresses that enter, the earlier the fig will lose its receptivity. We argue that the stimuli in male and female figs are adaptations to the fulfillment of its respective reproduction. [source] The calcium-conducting ion channel transient receptor potential canonical 6 is involved in macrophage inflammatory protein-2-induced migration of mouse neutrophils,ACTA PHYSIOLOGICA, Issue 1 2009N. Damann Abstract Aim:, The role of the calcium-conducting ion channel transient receptor potential canonical 6 (TRPC6) in macrophage inflammatory protein-2 (MIP-2) induced migration of mouse neutrophils was investigated. Methods:, Neutrophil granulocytes isolated from murine bone marrow of wild-type (TRPC6+/+) and TRPC6 knockout (TRPC6,/,) mice were tested for the presence of TRPC6 channel expression using quantitative real-time polymerase chain reactions and immunocytochemistry. The effect of different stimuli (e.g. MIP-2, 1-oleoyl-2-acetyl-sn-glycerol, formyl-methionyl-leucyl-phenylalanin) on migration of isolated neutrophils was tested by two-dimensional (2D) migration assays, phalloidin staining and intracellular calcium imaging. Results:, We found that neutrophil granulocytes express TRPC6 channels. MIP-2 induced fast cell migration of isolated neutrophils in a 2D cell-tracking system. Strikingly, MIP-2 was less potent in neutrophils derived from TRPC6,/, mice. These cells showed less phalloidin-coupled fluorescence and the pattern of cytosolic calcium transients was altered. Conclusions:, We describe in this paper for the first time a role for transient receptor potential (TRP) channels in migration of native lymphocytes as a new paradigm for the universal functional role of TRPs. Our data give strong evidence that TRPC6 operates downstream to CXC-type Gq -protein-coupled chemokine receptors upon stimulation with MIP-2 and is crucial for the arrangement of filamentous actin in migrating neutrophils. This is a novel cell function of TRP channel beyond their well-recognized role as universal cell sensors. [source] Development of a Controlled Release System for Risperidone Using Polypyrrole: Mechanistic StudiesELECTROANALYSIS, Issue 4 2010Darren Svirskis Abstract Polypyrrole (PPY) film has been selected as a platform material for drug delivery due to its inherent conductivity, ease of preparation and apparent biocompatibility. PPY films were prepared containing the antipsychotic drug risperidone as a model compound. Drug release profiles could be altered by applying different electrical stimulation to these films. Atomic force microscopy was used to investigate changes in PPY film thickness when different stimuli were applied. The highest levels of drug release were observed when PPY was reduced; this was accompanied by expansion of the film. Technology such as this could be utilized for implantable drug delivery devices, where the dose could be adjusted by external signaling. [source] Toxicological assessment of chemicals using Caenorhabditis elegans and optical oxygen respirometryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2009Katherine Schouest Abstract Oxygen consumption is indicative of an organism's metabolic state, whereby alterations in respiration rate can result from the presence of different stimuli. Here, we develop a novel approach based on quenched fluorescence oxygen sensing and respirometry method for toxicity screening assays using the nematode Caenorhabditis elegans. Previously, C. elegans was established as a useful model in soil and aquatic toxicology studies. For existing toxicology screening approaches with C. elegans, however, the endpoint is lethality. In addition, the assay time frame for the existing approaches is considerably longer than that for the approach described here. We present a sensitive, robust, high-throughput platform using standard laboratory equipment for toxicological studies by measuring respiration rate in C. elegans animals using a phosphorescent probe. [source] Behavioral Syndromes in Stable Social Groups: An Artifact of External Constraints?ETHOLOGY, Issue 12 2008Ximena J. Nelson Individuals of many species differ consistently in their behavioral reactions toward different stimuli, such as predators, rivals, and potential mates. These typical reactions, described as ,behavioral syndromes' or ,personalities,' appear to be heritable and therefore subject to selection. We studied behavioral syndromes in 36 male fowl living in 12 social groups and found that individuals behaved consistently over time. Furthermore, responses to different contexts (anti-predator, foraging, and territorial) were inter-correlated, suggesting that males exhibited comparable behavioral traits in these functionally distinct situations. We subsequently isolated the same roosters and conducted tests in a ,virtual environment,' using high-resolution digital video sequences to simulate the anti-predator, foraging, and territorial contexts that they had experienced outdoors. Under these controlled conditions, repeatability persisted but individual responses to the three classes of stimuli failed to predict one another. These were instead context-specific. In particular, production of each type of vocal signal was independent, implying that calls in the repertoire are controlled by distinct mechanisms. Our results show that extrinsic factors, such as social position, can be responsible for the appearance of traits that could readily be mistaken for the product of endogenous characters. [source] Neuronal representation of odourants in the olfactory bulb of Xenopus laevis tadpolesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2003Dirk Czesnik Abstract When an odourant enters the nose, olfactory receptor neurons (ORNs) convey information about it to the olfactory bulb (OB), where this information is processed and where the first central representations of the odourant are generated. In this paper we show how odourants are represented by ensembles of OB neurons, in particular mitral cells (MCs) which are the output neurons of the OB. We were able to demonstrate for the first time that the intracellular calcium concentrations ([Ca2+]i) in the somata of these neurons undergo specific changes and that different stimuli are represented by different neuronal [Ca2+]i patterns. The similarity of patterns was assessed by cross-correlation analysis. We further show that noradrenaline (NA), which is reported to be involved in olfactory memory formation and to modulate synaptic transmission at dendrodendritic synapses in the OB, profoundly changes the representation of odourants at the level of MCs. [source] Routes to party choice: Ideology, economic evaluations and voting at the 1997 British General ElectionEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 3 2001C.J. PATTIE Most conventional accounts of voting behaviour fit single models to the entire electorate, implicitly assuming that all voters respond to the same sets of influences, and do so in similar ways. However, a growing body of research suggests that this approach may be misleading, and that distinct groups of voters approach politics, and the electoral decision, from different perspectives. The paper takes a disaggregated look at voting in the 1997 British General Election, dividing voters into different groups according to their formal educational qualifications. Results suggest that different groups of voters respond to different stimuli, depending on their education, and on the party they are voting for. [source] Microgel-Based Stimuli-Responsive CapsulesADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Sebastian Berger Abstract In this paper, a preparation of stimuli-responsive capsules based on aqueous microgels is described. Microgel particles act as stabilizers for oil-in-water emulsion and organize themselves on the surface of chloroform droplets containing the biodegradable polymer poly(4-hydroxybutyrate- co -4-hydroxyvalerate) (PHBV). After chloroform evaporation, composite capsules consisting of a thin PHBV wall with integrated microgels are obtained. Due to the presence of microgels acting as sensitive building blocks, the capsules respond to different stimuli (temperature, solvent concentration). Preliminary results indicate that the capsule dimensions and morphology can be tuned by microgel and PHBV concentration in water and chloroform, respectively. [source] Stimuli for nestling begging in blue tits Cyanistes caeruleus: hungry nestlings are less discriminatingJOURNAL OF AVIAN BIOLOGY, Issue 4 2007Megan Dickens In altricial birds, nestlings usually respond to the sound and appearance of the provisioning adults by begging for food when the adults arrive at the nest. Nestlings can, however, also beg incorrectly on hearing misleading sounds in the environment and fail to beg when the adult arrives. This study uses the blue tit Cyanistes caeruleus to test the hypotheses that nestling begging strategies are influenced by the reliability of the stimulus to beg, and that nestling motivational state affects the response to different stimuli. Here, we show experimentally that nestling hunger strongly influences the response to stimuli that vary in their reliability. While hunger increases begging rate, it also increases the likelihood that nestlings will beg when the parent is absent. This is in agreement with both the predictions of signal detection theory and recent empirical work on other species. We found, however, no evidence that age-related perceptual constraints influence the begging response of ten day old nestlings to different stimuli. [source] Adapter protein CRKII signaling is involved in the rat pancreatic acini response to reactive oxygen speciesJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2006Alberto G. Andreolotti Abstract Recent studies demonstrate that reactive oxygen species (ROS) are important mediators of acute pancreatitis, whether induced experimentally or in necrotizing pancreatitis in humans; however, the cellular processes involved remain unclear. Adapter protein CrkII, plays a central role for convergence of cellular signals from different stimuli. Cholecystokinin (CCK), which induces pancreatitis, stimulates CrkII tyrosine phosphorylation and CrkII protein complexes, raising the possibility it can be important in the acinar cell responses to ROS. Therefore, our aim was to investigate whether CrkII signaling is involved in the biological response of rat pancreatic acini to H2O2 and the intracellular mediators implicated. Treatment of isolated rat pancreatic acini with H2O2 rapidly stimulates CrkII phosphorylation, measured as electrophoretic mobility shift and by using a phosphospecific antibody (pTyr221). Tyrosine kinase blocker B44 inhibits the higher phosphorylation state, demonstrating that it occurs mainly in tyrosine residues. H2O2 -induced CrkII phosphorylation is time- and concentration-dependent, showing maximal effect with 3 mM H2O2 at 5 min. The intracellular pathways induced by H2O2 leading to CrkII tyrosine phosphorylation do not involve PKC, intracellular calcium, PI3-K or the actin cytoskeleton integrity. ROS generation clearly promotes the formation of protein complex CrkII,PYK2. In conclusion, ROS clearly affect the key adapter protein CrkII signaling by two ways: stimulation of CkII phosphorylation and a functional consequence: formation of CrkII,protein complexes. Because of its central role in activating more distal pathways, CrkII might likely play an important role in the ability of ROS to induce pancreatic cellular injury and pancreatitis. J. Cell. Biochem. © 2005 Wiley-Liss, Inc. [source] A review of acoustic playback techniques for studying avian vocal duetsJOURNAL OF FIELD ORNITHOLOGY, Issue 2 2010Sarah B. Douglas ABSTRACT Playback experiments involve the broadcast of natural or synthetic sound stimuli and provide a powerful tool for studying acoustic communication in birds. Playback is a valuable technique for exploring vocal duetting behavior because it allows investigators to test predictions of the various hypotheses for duet function. Here, we adopt a methodological perspective by considering various challenges specific to studying duetting behavior, and highlighting the utility of different playback designs for testing duet function. Single-speaker playback experiments allow investigators to determine how duetting birds react to different stimuli, but do not simulate duets in a spatially realistic manner. Multi-speaker playback experiments are superior to single-speaker designs because duet stimuli are broadcast with spatial realism and unique and additional predictions can be generated for testing duet function. In particular, multi-speaker playback allows investigators to evaluate how birds respond to male versus female duet contributions separately, based on reactions to the different loudspeakers. Interactive playback allows investigators to ask questions about the time- and pattern-specific singing behavior of birds, and to understand how singing strategies correspond to physical behavior during vocal interactions. Although logistically challenging, interactive playback provides a powerful tool for examining specific elements of duets (such as the degree of coordination) and may permit greater insight into their functions from an operational perspective. Interactive playback designs where the investigator simulates half of a duet may be used to describe and investigate the function of pair-specific and population-wide duet codes. Regardless of experimental design, all playback experiments should be based on a sound understanding of the natural duetting behavior of the species of interest, and should aim to produce realistic and carefully controlled duet simulations. Future studies that couple playback techniques with other experimental procedures, such as Acoustic Location System recordings for monitoring the position of birds in dense vegetation or multimodal techniques that combine acoustic with visual stimuli, are expected to provide an even better understanding of these highly complex vocal displays. RESUMEN Los experimentos de reproducción de sonidos grabados involucran el uso de sonido natural o sintético y proveen una herramienta poderosa para el estudio de la comunicación acústica de las aves. La reproducción de sonidos grabados es una técnica valiosa para explorar las duetas vocales porque permite probar las predicciones de varios hipótesis sobre la función de duetas. Aquí, adoptamos una perspectiva metodológica, considerando los varios retos específicos al estudio del comportamiento de duetas y resaltando la utilidad de diferentes diseños de reproducción de sonidos grabados para probar la función de las duetas. Experimentos de reproducción de sonidos grabados hechas con un parlante permiten una determinación de como las aves que realizan duetas reaccionan a diferentes estímulos, pero no simulan las duetas de una manera espacialmente realística. Experimentos de reproducción de sonidos grabados hechas con múltiples parlantes son superiores a diseños con un solo parlante porque transmiten el sonido de una manera espacialmente realística y generan predicciones únicas y adicionales para probar la función de la dueta. En particular, la reproducción de sonidos grabados con múltiples parlantes permite una evaluación de cómo las aves responden a las contribuciones del macho y de la hembra separadamente, basado en sus reacciones a los diferentes parlantes. La reproducción de sonidos grabados interactiva permite hacer preguntas temporalmente especificas y en relación a patrones especificas sobre el comportamiento de canto. También permite entender como las estrategias de canto corresponden al comportamiento físico durante las interacciones vocales. Aunque es un reto logístico, la reproducción de sonidos grabados interactiva provee una herramienta poderosa para examinar elementos específicos de las duetas (como el grado de coordinación) y podría permitir un mayor conocimiento sobre sus funciones de una perspectiva operacional. Los diseños de la reproducción de sonidos grabados interactivas, en la cual el investigador simula la mitad de una dueta, podrían ser usadas para describir e investigar la función de los códigos de dueta específicos a una pareja y a una población. Sin importar el tipo de diseño experimental, todos los experimentos de reproducción de sonidos grabados deberían ser basadas en una buena comprensión del comportamiento natural de las duetas en la especie de interés, y deberían tener la meta de producir simulaciones de duetas realísticas y cuidadosamente controladas. Se espera que los estudios futuros cuales combinan técnicas de la reproducción de sonidos grabados con otros procedimientos experimentales, como grabaciones del Sistema de Ubicación Acústica para monitorear la posición de aves en vegetación densa, o técnicas multimodales que combinan estímulos acústicos con estímulos visuales, provean un mejor entendimiento de estos despliegues vocales altamente complejos. [source] Adenosine in the central nervous system: release mechanisms and extracellular concentrationsJOURNAL OF NEUROCHEMISTRY, Issue 3 2001Serena Latini Adenosine has several functions within the CNS that involve an inhibitory tone of neurotransmission and neuroprotective actions in pathological conditions. The understanding of adenosine production and release in the brain is therefore of fundamental importance and has been extensively studied. Conflicting results are often obtained regarding the cellular source of adenosine, the stimulus that induces release and the mechanism for release, in relation to different experimental approaches used to study adenosine production and release. A neuronal origin of adenosine has been demonstrated through electrophysiological approaches showing that neurones can release significant quantities of adenosine, sufficient to activate adenosine receptors and to modulate synaptic functions. Specific actions of adenosine are mediated by different receptor subtypes (A1, A2A, A2B and A3), which are activated by various ranges of adenosine concentrations. Another important issue is the measurement of adenosine concentrations in the extracellular fluid under different conditions in order to know the degree of receptor stimulation and understand adenosine central actions. For this purpose, several experimental approaches have been used both in vivo and in vitro, which provide an estimation of basal adenosine levels in the range of 50,200 nm. The purpose of this review is to describe pathways of adenosine production and metabolism, and to summarize characteristics of adenosine release in the brain in response to different stimuli. Finally, studies performed to evaluate adenosine concentrations under physiological and hypoxic/ischemic conditions will be described to evaluate the degree of adenosine receptor activation. [source] Ethanol-Induced Malfunction of Neutrophils Respiratory Burst on Patients Suffering From Alcohol DependenceALCOHOLISM, Issue 10 2008Dirk Breitmeier Background:, Polymorphonuclear, neutrophil granulocytes (PMN) play a major role in the control of infections, and people who abuse alcohol are susceptible to infections. Resistance against infections ensues intracellularly following initial phagocytosis of microorganisms with the oxygen-dependent respiratory burst, the key enzyme of which is the respiratory burst oxidase, whereby oxygen radicals are produced for microbial destruction. To date there is insufficient information available in connection with the process of impaired defence against infection in patients suffering from alcohol dependence. Therefore, our investigation was carried out to determine the influence of alcohol exposition on the formation of oxygen radicals and the respiratory burst. Methods:, 4.5 ml of whole blood was taken from 10 healthy adults and 10 patients suffering from alcohol dependence. An additional 3.5 ml of whole blood was taken from the alcoholic patients for determination of the blood alcohol concentration. The respiratory burst of PMN was tested using the Four-Colour-Continuous Flow Cytometer. Each experimental procedure consisted of 4 test samples [negative controls, Escherichia coli, FMLP-supplement (N-formyl-l-methionyl-l-leucyl-l-phenylalanin), PMA-supplement (phorbol-12-myristate-13-acetate)]. Differing concentrations of ethanol were also introduced to each of the tests performed (0.20 to 4.00 g/l). Results:, Ethanol revealed a marked decrease of burst activity in those patients suffering from alcoholism with increased alcohol concentration. A dependence between the burst activity and the ethanol concentration was seen to be statistically significant. This effect was only evident after stimulation with E. coli and FMLP in those patients with alcohol dependence. Conclusion:, The results presented in this study show an impairment in the function of PMN in those patients addicted to alcohol due to the decrease in burst activity. In view of the results of the different stimuli, the second-messenger effects were not evident. A clarification of this phenomenon could well be assumed as an allosteric receptor effect on the burst oxidase, namely, a direct effect on the phagocytosis interaction between circulating granulocytes and causative organisms. [source] Role of mitogen-activated protein kinases in phenethyl isothiocyanate-induced apoptosis in human prostate cancer cellsMOLECULAR CARCINOGENESIS, Issue 3 2005Dong Xiao Abstract The present study was undertaken to examine the role of mitogen-activated protein kinases (MAPKs) in apoptosis induction by phenethyl isothiocyanate (PEITC), a cruciferous vegetable-derived cancer chemopreventive agent, with DU145 and LNCaP human prostate cancer cells as a model. The MAPK family of serine/threonine kinases, including extracellular signal-regulated kinase1/2 (ERK1/2), c- jun N-terminal kinase1/2/3 (JNK1/2/3), and p38 MAPK play an important role in cell proliferation and apoptosis in response to different stimuli. Exposure of DU145 and LNCaP cells to growth suppressive concentrations of PEITC resulted in activation of ERK1/2 and JNKs, but not p38 MAPK, in both cell lines. In DU145 cells, the apoptosis induction by PEITC was statistically significantly attenuated by pharmacological inhibition of JNKs with SP600125. Adenovirus-mediated overexpression of Flag-tagged JNK binding domain (JBD) of JNK-interacting protein-1 (JIP-1), an inhibitor of JNK, also inhibited PEITC-induced apoptosis in DU145 cells. On the other hand, inhibition of ERK1/2 activation with MEK1 inhibitor PD98059 failed to offer protection against PEITC-induced apoptosis in DU145 cells. In LNCaP cells, the PEITC-induced cell death was not affected by either pretreatment with PD98059 or SP600125 or overexpression of JBD of JIP-1. These results indicate that involvement of MAPKs in apoptosis induction by PEITC in human prostate cancer cells is cell line-specific. © 2005 Wiley-Liss, Inc. [source] Modulation of Mycobacterium tuberculosis proliferation by MtrA, an essential two-component response regulatorMOLECULAR MICROBIOLOGY, Issue 3 2006Marek Fol Summary Paired two-component regulatory systems consisting of a sensor kinase and a response regulator are the major means by which bacteria sense and respond to different stimuli. The role of essential response regulator, MtrA, in Mycobacterium tuberculosis proliferation is unknown. We showed that elevating the intracellular levels of MtrA prevented M. tuberculosis from multiplying in macrophages, mice lungs and spleens, but did not affect its growth in broth. Intracellular trafficking analysis revealed that a vast majority of MtrA overproducing merodiploids were associated with lysosomal associated membrane protein (LAMP-1) positive vacuoles, indicating that intracellular growth attenuation is, in part, due to an impaired ability to block phagosome,lysosome fusion. A merodiploid strain producing elevated levels of phosphorylation-defective MtrA (MtrAD53N) was partially replicative in macrophages, but was attenuated in mice. Quantitative real-time PCR analyses revealed that expression of dnaA, an essential replication gene, was sharply upregulated during intramacrophage growth in the MtrA overproducer in a phosphorylation-dependent manner. Chromatin immunoprecipitation using anti-MtrA antibodies provided direct evidence that MtrA regulator binds to dnaA promoter in vivo indicating that dnaA promoter is a MtrA target. Simultaneous overexpression of mtrA regulator and its cognate mtrB kinase neither inhibited growth nor sharply increased the expression levels of dnaA in macrophages. We propose that proliferation of M. tuberculosis in vivo depends, in part, on the optimal ratio of phosphorylated to non-phosphorylated MtrA response regulator. [source] Relevance of caspase activity during apoptosis in pubertal rat spermatogenesisMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 5 2008Veronica A. Codelia Abstract Caspases are a family of cysteine-proteases, activated upon several different stimuli, which execute apoptosis in many cell death models. Previous work of our group has shown rats have the highest rate of apoptosis during the first wave of spermatogenesis (between 20 and 25 days after birth), as evaluated by TUNEL and caspase activity. However, the hierarchical order of caspase activation and the relevance of each caspase during germ cell apoptosis are not clear. Thus, the goal of this work is to take a pharmacological approach to dissect the apoptosis pathway of caspase activation. Results showed that intratesticular injection of a caspase-8 inhibitor (z-IETD-fmk), or a pan-caspase inhibitor (z-VAD- fmk), significantly decreased the cleavage of p115 and PARP, two endogenous substrates of caspases, in 22-day-old rats. Additionally, these inhibitors promoted a significant reduction in the number of apoptotic germ cells. On the other hand, intratesticular injection of two different inhibitors of the intrinsic pathway (z-LEHD-fmk and minocycline) did not have any effect upon caspase substrates cleavage (p115 and PARP) or the number of apoptotic germ cells. Therefore, we conclude that the extrinsic pathway of apoptosis plays an important role in physiological germ cell apoptosis during the first round of spermatogenesis in the rat. Mol. Reprod. Dev. 75: 881,889, 2008. © 2007 Wiley-Liss, Inc. [source] Alterations of intestinal motor responses to various stimuli after Nippostrongylus brasiliensis infection in rats: role of mast cellsNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2000J. Gay Nippostrongylus brasiliensis infection induces jejunal mastocytosis associated with enteric nerve remodelling in rats. The aim of this study was to evaluate the intestinal motility responses to meals and to neurotransmitters involved in the control of gut motility (acetylcholine (carbachol), substance P and neurokinin A) in both control and N. brasiliensis -infected rats 30 days post-infection. All rats were equipped with NiCr electrodes in the jejunum to record myoelectrical activity. The duration of disruption of the jejunal migrating myoelectrical complexes (MMC) induced by the different stimuli was determined. Meal ingestion and substance P administration disrupted the MMC pattern for similar durations in the two groups. Carbachol and neurokinin A induced a significantly longer MMC disruption in post-infected rats than in controls (125 ± 8.3 vs. 70 ± 6 min for carbachol 100 ,g kg,1 and 51 ± 4 vs. 40 ± 2 for neurokinin A 50 ,g kg,1). The enhanced motor response in postinfected rats was reduced by previous mast cell stabilization with ketotifen or mast cell degranulation with compound BrX 537 A. In conclusion, the increased intestinal motor reactivity to carbachol and neurokinin A in post- N. brasiliensis -infected rats depends upon intestinal mast cell hyperplasia and degranulation. [source] Can We Increase the Estimative Value of Semen Assessment?*REPRODUCTION IN DOMESTIC ANIMALS, Issue 2006H Rodríguez-Martínez Contents Estimating the fertility of a semen sample or of the male from where it has been collected by simple assessment of in vitro sperm characteristics is still difficult, owing to the variable correlations that laboratory results achieve with in vivo fertility. A major reason behind these variations is the fact that the ejaculate and the artificial insemination (AI)-doses it generates are composed of a diverse sperm population. Such heterogeneity is reflected both in differences of intactness of attributes needed for fertilization, such as motility or morphology, but also in the relative ability of spermatozoa to prevail fertile over time, handling and exposure to different stimuli, all of which account for innate variations in fertilizing ability among doses, ejaculates and sires. However, methods are already available to select sub-populations of intact spermatozoa which can be tested for their degree of competence for fertilization and whose estimative power is promising, allowing the elimination of cases of sub-fertility, particularly in bovine. Examples of these methods are the separation of viable spermatozoa by swim-up or discontinuous gradient centrifugation, followed by testing the ability of the selected spermatozoa to dose-response/time sustain capacitation and acrosome reaction induction. Finding how large a sperm population with non-compensable attributes for fertilization and ability to display and sustain stimuli is, perhaps by a quick screening of membrane integrity and stability by multi-parametric methods, would allow, provided the particular male produces this sub-population in a repeatable manner, for a better estimation of fertility. [source] Acrosome reaction: methods for detection and clinical significanceANDROLOGIA, Issue 6 2000T. Zeginiadou The present article reviews the methods for detection and the clinical significance of the acrosome reaction. The best method for the detection of the acrosome reaction is electron microscopy, but it is expensive and labour-intensive and therefore cannot be used routinely. The most widely used methods utilize optical microscopy where spermatozoa are stained for the visualization of their acrosomal status. Different dyes are used for this purpose as well as lectins and antibodies labelled with fluorescence. The acrosome reaction following ionophore challenge (ARIC) can separate spermatozoa that undergo spontaneous acrosome reaction from those that are induced, making the result of the inducible acrosome reaction more meaningful. Many different stimuli have been used for the induction of the acrosome reaction with different results. The ARIC test can provide information on the fertilizing capability of a sample. The ARIC test was also used to evaluate patients undergoing in vitro fertilization since a low percentage of induced acrosome reaction was found to be associated with lower rates of fertilization. The cut-off value that could be used to identify infertile patients is under debate. Therapeutic decisions can also be made on the basis of the value of the ARIC test. [source] Visualisation of human dental pulp vasculature by immunohistochemical and immunofluorescent detection of CD34: A comparative studyAUSTRALIAN ENDODONTIC JOURNAL, Issue 3 2006Anna Digka Abstract CD34 is considered a pan-endothelial cell marker for paraffin-embedded sections. In this study, both immunohistochemistry and immunofluorescence were applied in human dental pulp specimens of moderate thickness (10 µm) in order to observe the vasculature of this tissue using CD34. Both techniques revealed a homogenous staining pattern with capillaries and larger vessels showing complete and strong membrane staining reflecting the high capacity of the pulp for regeneration and response to different stimuli. A novel approach in the identification of the pulpal vasculature by Cy5-conjugated anti-CD34 is introduced in this study. By this technique the dense capillary plexus of the sub-odontoblastic region, which is responsible for the reaction of the tissue to any physical or chemical stimuli or pathological condition, can be clearly identified, while immunohistochemistry did not reveal such a detailed staining pattern. [source] Different Stimuli Reduce Attraction to Pollinators in Male and Female Figs in the Dioecious Fig Ficus hispidaBIOTROPICA, Issue 6 2009Hao-Yuan Hu ABSTRACT Fig trees (Ficus) and their obligate pollinating wasps (Hymenoptera, Chalcidoidea, Agaonidae) are a classic example of a coevolved mutualism. Pollinating wasps are attracted to figs only when figs are receptive. It has been shown that figs will lose their attraction to pollinators sooner in monoecious and male dioecious figs when multiple pollinators have entered the enclosed inflorescence. However, little is known about the nature of the stimulus inducing the loss of attraction. By conducting experiments on the functionally dioecious fig, Ficus hispida, we show that (1) different stimuli induce the loss of attraction in each sex, pollination in female figs, and oviposition in male figs; and (2) foundress number affects the loss of attraction in both sexes only when the prerequisites (i.e., pollination in female figs and oviposition in male figs) have been satisfied. In general, the more foundresses that enter, the earlier the fig will lose its receptivity. We argue that the stimuli in male and female figs are adaptations to the fulfillment of its respective reproduction. [source] Contrasting effects of HSP72 expression on apoptosis in human umbilical vein endothelial cells and an angiogenic cell line, ECV304BRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2000M. Lucas The effect of overexpression of heat shock protein (HSP)72 on apoptosis induced by different stimuli in human umbilical vein endothelial cells (HUVECs) and the angiogenic cell line, ECV304, was studied. Transient overexpression of HSP72 was achieved using an adenoviral vector (Advhsp72) and apoptosis was induced by heat shock, tumour necrosis factor (TNF)-, with cycloheximide (CHX), lipopolysaccharide (LPS) with TNF-, and verocytotoxin (VT). Apoptosis induced by heat shock was reduced by HSP72 expression. However, HSP72 expression in HUVECs increased apoptosis induced by TNF-,/CHX, LPS and VT measured by flow cytometric analysis of propidium iodide (PI)-stained permeabilized cells. In contrast, apoptosis in ECV304 induced by the same stimuli was reduced by HSP72 expression. No difference was seen in cells transduced with a control adenoviral vector expressing ,-galactosidase. These data imply that induction of HSP72 in cells modulates responses to apoptotic stimuli, but that the nature of the response varies with the cell type. However, it is clear that in situations where apoptosis may be part of a pathological process, HSP72 induction, for example by reperfusion injury, may exacerbate the process. [source] Selective induction of nerve growth factor and brain-derived neurotrophic factor by LPS and allergen in dendritic cellsCLINICAL & EXPERIMENTAL ALLERGY, Issue 3 2008O. Noga Summary Background Neurotrophins are produced by various cells upon different stimuli and participate in the initiation and regulation of inflammation in various diseases including allergy and asthma, but little is known about the production and control of neurotrophins by dendritic cells (DCs). The aim of this study was to assess whether DCs produce the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), and whether inflammatory stimuli or allergens are able to induce the production of neurotrophic factors. Methods Monocyte-derived dendritic cells (MoDCs) were generated from different donors. The neurotrophins NGF and BDNF were demonstrated by RT-PCR, Western blotting, flow cytometry analysis and fluorescence microscopy. MoDCs were cultured and stimulated with lipopolysaccharide (LPS) or allergen for 24 h. The supernatants and cells were collected. Measurement for NGF and BDNF was performed by ELISA. Results DCs express mRNA for the neurotrophins NGF and BDNF. Proteins were detectable by Western blot, FACS analysis and fluorescence microscopy. LPS led to an up-regulation of BDNF, while NGF was unaffected. Cell lysates demonstrated an increased amount of BDNF after stimulation with LPS or allergen, while NGF was not affected significantly. Conclusions DCs are a source of neurotrophins. LPS selectively regulates the production of BDNF. Allergen stimulation leads to an LPS-independent regulation. This contributes to a complex involvement of neurotrophins in allergic diseases. [source] Differential Frontal Cortex Activation Before Anticipatory and Reactive Saccades in InfantsINFANCY, Issue 2 2001Gergely Csibra Neural correlates of anticipatory and reactive saccades were studied in 4-month-old infants by recording high-density event-related potentials. Infants were presented with a fixed sequence of stimulus presentation to which they rapidly showed anticipatory saccades, as well as continuing with some reactive (stimulus-driven) saccades. As in a previous study, no clear evidence was found for adultlike, saccade-related potentials, although some presaccadic differences between reactive and anticipatory saccades were observed. Infants also showed different stimulus offset-related effects preceding the 2 types of trials with a right-frontal positivity when an anticipatory look follows, but only left-frontal positivity when a reactive saccade follows. [source] | ||||||||||||||||