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P A V Anderson - One of the best experts on this subject based on the ideXlab platform.

  • Cloning and functional expression of voltage-gated ion channel subunits from cnidocytes of the Portuguese Man O'War Physalia physalis.
    Journal of Experimental Biology, 2006
    Co-Authors: C Bouchard, R B Price, C G Moneypenny, L F Thompson, M Zillhardt, L Stalheim, P A V Anderson
    Abstract:

    SUMMARY Cnidocytes were dissociated from the tentacles of the Portuguese Man O9War Physalia physalis using heat treatment, and purified using density centrifugation. Visual observation confirmed that these cnidocytes contained a nucleus, a cnidocyst and an apical stereocilium, confirming that the cells were intact. A cnidocyte-specific amplified cDNA library was then prepared using RNA isolated from the cnidocytes, and screened for voltage-gated ion channel subunits using conventional molecular cloning techniques. A variety of channel proteins were identified and full-length sequence obtained for two of them, a Ca 2+ channel β subunit ( Pp Ca V β) and a Shaker -like K + channel ( Pp K V 1). The location of the transcripts was confirmed by RT-PCR of total RNA isolated from individually selected and rinsed cnidocytes. The functional properties of these two channel proteins were characterized electrophysiologically using heterologous expression. Pp Ca V β modulates currents carried by both cnidarian and mammalian α 1 subunits although the specifics of the modulation differ. Pp K V 1 produces fast transient outward currents that have properties typical of other Shaker channels. The possible role of these channel proteins in the behavior of cnidocytes is discussed.

  • Cloning and functional expression of voltage-gated ion channel subunits from cnidocytes of the Portuguese Man O'War Physalia physalis.
    The Journal of experimental biology, 2006
    Co-Authors: C Bouchard, R B Price, C G Moneypenny, L F Thompson, M Zillhardt, L Stalheim, P A V Anderson
    Abstract:

    Cnidocytes were dissociated from the tentacles of the Portuguese Man O'War Physalia physalis using heat treatment, and purified using density centrifugation. Visual observation confirmed that these cnidocytes contained a nucleus, a cnidocyst and an apical stereocilium, confirming that the cells were intact. A cnidocyte-specific amplified cDNA library was then prepared using RNA isolated from the cnidocytes, and screened for voltage-gated ion channel subunits using conventional molecular cloning techniques. A variety of channel proteins were identified and full-length sequence obtained for two of them, a Ca(2+) channel beta subunit (PpCa(V)beta) and a Shaker-like K(+) channel (PpK(V)1). The location of the transcripts was confirmed by RT-PCR of total RNA isolated from individually selected and rinsed cnidocytes. The functional properties of these two channel proteins were characterized electrophysiologically using heterologous expression. PpCa(V)beta modulates currents carried by both cnidarian and mammalian alpha(1) subunits although the specifics of the modulation differ. PpK(V)1 produces fast transient outward currents that have properties typical of other Shaker channels. The possible role of these channel proteins in the behavior of cnidocytes is discussed.

  • electrical responses to water soluble components of fish mucus recorded from the cnidocytes of a fish predator Physalia physalis
    Marine and Freshwater Behaviour and Physiology, 1995
    Co-Authors: J E Purcell, P A V Anderson
    Abstract:

    Physalia physalis, the Portuguese man of war, consumes mostly fish and fish larvae. Intracellular recordings from nematocyst‐containing cells (cnidocytes) in small pieces of Physalia tentacle were used to quantify the electrical responses to diluted and filtered fish skin mucus, 1–100 x 10‐6 M amino acids, monosaccharides, and nucleosides, and seawater, which were delivered upstream of the tissue. Seawater caused responses (one pulse only) in about 10% of the applications. Fish mucus extract elicited responses in all applications, producing 1–18 depolarizing pulses (20 mV maximum amplitude). The pulses were characteristic of post‐synaptic potentials (EPSPs). Lucifer yellow and biocytin dye injections showed that the cnidocytes were not electrically coupled. Simultaneous records from two cnidocytes following mucus applications were identical.We propose, therefore, that the chemoreceptors are not on the cnidocytes, but are probably on sensory neurons that innervate clusters of cnidocytes. A < 3,000 MW fract...

David A. Hessinger - One of the best experts on this subject based on the ideXlab platform.

  • apparent membrane pore formation by portuguese man of war Physalia physalis venom in intact cultured cells
    Toxicon, 2002
    Co-Authors: Lincoln Edwards, Ernest F Whitter, David A. Hessinger
    Abstract:

    Abstract Intracellular, ratiometric microfluorimetry with fura-2 reveals that low doses of Portuguese Man-of-war ( Physalia physalis ) venom cause a linear increase in intracellular calcium accumulation by cultured L-929 cells. The influx of calcium is preceded by a lag period that is relatively independent of venom concentration, except at very low concentrations. Electron micrographs of negatively stained preparations of membranes from venom-treated L-929 and GH 4 C 1 cells exhibit 10–80 nm diameter lesions. The number and diameter of these lesions correlate with venom concentration. The venom forms lesions in GH 4 C 1 cells at much lower concentrations than in L-929 cells. Osmotic protectants such as sucrose and polyethylene glycol (PEG), reduce the extent of lactate dehydrogenase (LDH) release from venom-treated cells with the higher molecular weight PEG causing a greater inhibition of LDH release than sucrose. These results imply that Man-of-war venom produces pore-like structures in the membranes of target cells, which leads to colloid osmotic swelling with subsequent release of intracellular proteins and cell lysis.

  • portuguese man of war Physalia physalis venom induces calcium influx into cells by permeabilizing plasma membranes
    Toxicon, 2000
    Co-Authors: Lincoln Edwards, David A. Hessinger
    Abstract:

    Abstract Portuguese Man-of-war (Physalia physalis) nematocyst venom dose-dependently stimulates calcium (45Ca2+) influx into L-929, GH4C1, FRL, and embryonic chick heart cells. Venom-induced calcium influx is not blocked by ouabain, vanadate, nor organic calcium channel blockers, but is blocked by transition metal cations, such as lanthanum and zinc. Venom-induced calcium influx is accompanied in a dose-dependent manner by the release of intracellular lactate dehydrogenase, indicating a loss in plasma membrane integrity and cytolysis. Concentrations of zinc that block 45Ca2+ influx also block lactate dehydrogenase release. Lanthanum, which also blocks 45Ca2+ uptake, does not neutralize the cytolytic activity of the venom, but rather inhibits the venom's cytolytic action at the level of the target cell plasma membrane. Our findings indicate that Man-of-war venom causes an influx of calcium into several different cells types, not just those of the cardiovascular system, and this influx likely occurs by permeabilizing the plasma membranes of cells.

Gary J Calton - One of the best experts on this subject based on the ideXlab platform.

Burnett Jw - One of the best experts on this subject based on the ideXlab platform.

Joseph W Burnett - One of the best experts on this subject based on the ideXlab platform.

  • Immunochromatography and cardiotoxicity of sea nettle (Chrysaora quinquecirrha) polyps and cysts.
    Toxicon, 2002
    Co-Authors: C.erik Olson, David G. Cargo, Gary J Calton, Joseph W Burnett
    Abstract:

    Abstract The cardiotoxicity and polypeptide content of sea nettle (Chrysaora quinquecirrha) polyps and cysts were studied. Crude polyp preparations were lethal to mice. Both crude polyp and cyst preparations were toxic to embryonic chick cardiocytes. The polyp cardiotoxin factor was purified ten-fold by immunosorbent chromatography using anti-sea nettle or anti-man-o'war (Physalia physalis) monoclonal antibodies. Even though the polyps were incubated at a constant temperature, it appeared that there was an inverse relationship between the presence of proteins of 160,000 and 55,000 mol. wt as winter progressed.

  • serious Physalia portuguese man o war stings implications for scuba divers
    Journal of Wilderness Medicine, 1994
    Co-Authors: Joseph W Burnett, Peter J Fenner, F Kokelj, John A Williamson
    Abstract:

    The objective of this study was to describe a serious jellyfish envenomation in a scuba diver by an Atlantic Physalia physalis , to review the related literature and to recommend safe diving practices that may reduce the risk of serious jellyfish envenomation in divers. A healthy scuba diving instructor wearing a full wetsuit and gloves but no hood ascended from a night dive and surfaced directly under a large Atlantic Physalia jellyfish. He suffered multiple severe stings to the unprotected areas of his face and neck. He developed acute subjective respiratory distress with hyperventilation, muscle pain and spasms, and impaired consciousness en route to hospital, more than 10 min following envenomation. He recovered quickly in hospital with oxygen, aminophylline and intravenous fluid administration. Delayed recovery of the envenomated skin took several weeks and serology was positive for Physalia venom antibodies. Full protective clothing (e.g. a full, long sleeved wetsuit, plus gloves and hood when appropriate) should be worn by scuba divers on all dives. Ascent routines in diving should include looking directly upwards at the surface with one wetsuited arm outstretched towards the surface throughout the ascent. Removal of tentacles should not be attempted by the diver until he or she has exited from the water.