1,721,099 research outputs found
The 11th symposium on Invertebrate Neurobiology, Tihany, Hungary, 2007
No full textThe 11th symposium on Invertebrate Neurobiology took place at the Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany, Hungary, from 25th to 29th August 2007. This Institute was founded in 1927 for the study of the hydrobiology of Lake Balaton. Around 70 participants registered for the symposium which took place under the auspices of the International Society for Invertebrate Neurobiology (ISIN). Participants attended from ten countries with the largest contingents coming from Germany, Hungary, Japan and Russia. ISIN was founded in 1987 during the sixth meeting to be held at the Institute on Invertebrate Neurobiology and Professor Dr. Janos Salanki was elected President of the Society. The first meeting on Neurobiology of Invertebrates, held in 1967, was organized by the then Director of the Institute, Professor Janos Salanki and coincided with the 40th anniversary of the Institute. Professor Salanki edited the volume of proceedings from the first symp
Multi sensor data fusion applied to a class of autonomous land vehicles
No full textMany applications exist for unmanned vehicles, factory maintenance, planetary exploration, in reactor inspection etc. Robotic systems will inhabit a world which will contain obstacles, these obstacles will threaten their pursuit of a successful goal. In all but the most simple and benign environment these obstacles will be in motion. The presence or location of an obstacle will not be known a priori. Therefore in order to build practical, useful robots a means of sensing the environment in order to determine traversable/non-traversable space needs to be developed. In addition, to prevent them from becoming lost, practical robots will be required to generate an estimate of where they are in the world in relation to known features, this capability is referred to as localisation. Clearly the primary sense for determining traversable spaces is sight. However current research into machine vision has produced systems that are either too slow, too specific (i.e. related to a particular problem domain rather than a general one) to too unreliable. These factors have lead to the development of an active sensor, the motion structured light sensor. This sensor solves the ill-posed problem and the problem of large data rates by illuminating the world with a laser sheet and determining 3D topography from the image of the intersection of this sheet and the world. The sensor has been developed to detect and track moving obstacles over time and has also been used as a means of vehicle localisation with respect to an a priori map. Although vision, and in particular structured light, is a useful source of topographic information, other sensors offer the ability to determine the presence of geometric features in a scene, such as ultrasonic sensors and laser rangefinders. Motivated by the desire to generate richer descriptions of world state from disparate information sources the research area of Multi Sensor Data Fusion (MSDF) is addressed. A mechanism for combining information based on the first and second order statistics available from the Kalman filter is presented. The MSDF system is applied i) in simulation to a second order plant and ii) to a laboratory based robot. This approach leads to greater accuracy of state estimation which leads to greater system robustness and robustness with respect to sensor failure / sensor error. This thesis therefore presents a method of generating more accurate estimates of state by using multiple sources of information. This enables systems to be built that are more robust, not only due to the fact that state estimates are more accurate but also due to the fact that these systems will possess multiple redundancy through the use of multiple sensors. It is shown that the use of multiple sensors also enables the system to become more robust with respect to the poor chose of noise models required by the Kalman filter
Actions of nematode FMRFamide-related peptides on the pharyngeal muscle of the parasitic nematode, Ascaris suum
No full textThe endogenous nematode peptides known as FMRFamide-related peptides (FaRPs) and various “classical” transmitters have a range of effects on nematodes that result in changes in behavior, particularly locomotion, including paralysis and inhibition of feeding. This study describes the application of an in vitro pharmacological approach to further delineate the action of a number of FaRP neurotransmitters on feeding behavior. Contraction of Ascaris suum pharyngeal muscle was monitored using a modified pressure transducer system that detects changes in intrapharyngeal pressure and therefore contraction of the radial muscle of the pharynx. The pharynx did not contract spontaneously. However, serotonin (5-HT, 100 µM) stimulated rhythmic contractions and relaxations (pumping) at a frequency of 0.5 Hz. The native nematode peptide, KNEFIRFamide (AF1), inhibited the pumping elicited by 5-HT. The duration of inhibition was concentration-dependent (1-1000 nM) with a threshold of 1 nM (n= 7). KSAYMRFamide (AF8/PF3) also inhibited pharyngeal pumping. There was no observable effect of any of the following nematode peptides on pharyngeal pumping behavior (1-1000 nM; n= 8): AF2, AF3, AF4, AF6, AF16, PF1/CF1, PF2/CF2, or PF4. Thus, interruption of pharyngeal processes, such as feeding, regulation of hydrostatic pressure, and secretion, may provide a new site of anthelmintic action
Physiological actions of putative neuropeptides in the nematode Ascaris suum
No full textNeuropeptide-like immunoreactivity has a widespread distribution in the nematode nervous system (Sithigorngul et al. 1990) and sequences of more than 150 neuropeptides have been predicted from the genomes of C. elegans (Nelson et al. 1998; Nathoo et al. 2001). Here we report a preliminary assessment of the biological activity of six of these on the somatic muscle of the parasitic nematode A. suum. Three of these are encoded by flp (FMRFamide-like peptides) genes and three by nlp (neuropeptide-like precursor) genes. Two of the latter show some sequence similarity to myomodulin, and one to buccalin, molluscan neuropeptides.The effect of the peptides on the body wall muscle of A. suum was determined using an in vitro preparation of dorsal muscle strips as described by Trim et al. (1997). A 1 cm section of muscle was placed in an organ bath attached to an isometric transducer and perfused with artificial perienteric fluid (composition (mM): NaCl 67, sodium acetate 67, MgCl2 5.6, CaCl2 3, KCl 3, Tris-Cl 5; pH 7.6). The excitatory neuromuscular junction transmitter acetylcholine (ACh; 10 µM) was added for 1 min and then washed out. This elicited a rapid and reversible contraction. This was repeated twice to obtain contractions of reproducible amplitude. Subsequently the neuropeptide was added to the preparation 2 min prior to ACh, and the amplitude of the contraction to ACh in the presence of the peptide was expressed as a percentage of the average amplitude of the three contractions prior to the addition of neuropeptide. None of the neuropeptides had a marked effect on basal muscle tension. However, three had a potent effect on the contraction elicited by ACh, with two acting as inhibitors and one as a potentiator. The results are summarised in Table 1.In conclusion, all three of the RF-amide neuropeptides had potent effects, and one of the myomodulin-like peptides had a weak inhibitory action. Further studies are in progress to assess the activity of these peptides in C. elegans. <br/
Structure–activity and possible mode of action of S-Iamide neuropeptides on identified central neurons of Helix aspersa
No full textIntracellular recordings were made from identified neurons from the suboesophageal ganglia of Helix aspersa. The inhibitory action of nine S-Iamide peptides was investigated. Structure–activity studies suggest that all act through a common receptor, which normally requires FVRIamide at the C terminal, with a preferred length of seven amino acids. Substitution at the N-terminal with alanine (A), threonine (T), proline (P) or leucine (L) results in little change in potency, suggesting the N-terminal requirements are relatively flexible. Ion substitution experiments suggest that potassium is the main ion involved in the inhibitory response to S-Iamide application. Studies using a range of compounds, which modify second messenger systems, would suggest that S-Iamide peptides may interact with adenylate cyclase. No evidence was found for an interaction with either guanylate cyclase or nitric oxide synthas
Evidence for a possible role for nitric oxide in the modulation of heart activity in Achatina fulica and Helix aspersa
No full textThe effects of nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine, S-nitroso--glutathione, sodium nitroprusside and sodium nitrite were investigated on the activity of the isolated hearts of Achatina fulica and Helix aspersa. NO donors inhibited heart activity in a concentration-dependent manner. The only exception was sodium nitroprusside, which excited H. aspersa heart. The inhibitory effects of these NO donors were reduced by the NO scavenger, methylene blue, the guanylyl cyclase inhibitor, 1H-(1,2,4) Oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), and potentiated by 8-Br-cGMP and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Acetylcholine also inhibited the heart activity, and this inhibition was reduced by methylene blue and ODQ. Positive NADPH-diaphorase staining was located in the outer pericardial layer of the heart of A. fulica. The present results provide evidence that NO may modulate the activity of gastropod hearts, and this modulation may modify the inhibitory action of acetylcholine on heart activity
A Multi-Sensor Fusion System for a Laboratory Based Autonomous Vehicle
No full textMotivated by the desire to generate richer descriptions of world state from disparate information sources the research area of Multi Sensor Data Fusion (MSDF) based upon a distributed Kalman Filter is addressed in this paper. To demonstrate the approach the MSDF system is applied i) in simulation to a second order plant and ii) to a laboratory based robot. MSDF research has demonstrated greater accuracy of state estimation which leads to greater system robustness with respect to sensor failure/sensor error. In addition the application of MSDF to systems with zero mean noise processes generates a Kalman filtered state estimate that is less sensitive to poor choices of system and process noise models
A possible mechanism for the action of the novel anthelmintic emodepside, using Ascaris suum body wall muscle preparations
No full textThe increasing resistance of parasitic nematodes, to existing anthelmintics has encouraged the search for novel compounds. A potential anthelmintic PF1022A, a 24 membered cyclic depsipeptide, has been shown to act as a potent broad-spectrum anthelmintic (Von Samson-Himmelstjerna et al. 2000). PF1022A causes a fast onset of paralysis of the nematodes, favouring the view that it is neuropharmalogically active. This study investigates the in vitro effects of a semi-synthetic, structurally similar derivative, emodepside, on the pig intestinal parasite Ascaris suum. Ascaris dorsal muscle strips (DMS) were bathed in artificial perienteric fluid (APF) (Trim et al. 1997). Statistical comparison was by Student's paired or unpaired t test, as stated. As a control, the DMS was contracted using acetylcholine (30 µM, 10 min) and maximum contraction was normalised to 100 %. A slow relaxation of the DMS was then observed over a period of 10 min. Addition of 10 µM emodepside at the point of maximum contraction, caused a significantly (P < 0.005, unpaired) faster relaxation of the DMS, 9.0 ± 0.3 % min-1 (mean ± S.E.M., n = 5), compared with the ACh control (6.1 ± 0.6 % min-1, n = 5).The effects of emodepside on Ascaris somatic muscle cells were investigated using a 2-microelectrode set-up. A 2 min perfusion of emodepside over muscle cells caused a significant (P < 0.001, paired) slow hyperpolarisation of 5.5 ± 0.96 mV (n = 8), with no change in input conductance after 30 min. In the absence of calcium, 10 µM emodepside caused no significant change in membrane potential. Re-introduction of calcium resulted in a slow significant (P < 0.002, paired) hyperpolarisation of 5.5 ± 1.1 mV (n = 8).Perfusion of the muscle cells with the potassium channel blockers 4-aminopyridine (4AP, 250 µM) and tetra-ethylammonium (TEA, 5 mM) resulted in a slight depolarisation of muscle cells 2.8 ± 0.5 mV (n = 5). Emodepside (10 µM) was then applied, and no significant change in the membrane potential occurred. Following wash-out of 4AP and TEA, the membrane potential hyperpolarized by 5.2 ± 2 mV (n = 5) over a 30 min period, although this effect was not significant. These results indicate that potassium is required for emodepside hyperpolarisation and this, combined with the results with calcium-free APF, suggests that this compound's relaxation effect may be mediated via a calcium-activated potassium channel. <br/
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