(n.) One of a series of flat, fringed, and usually bilobed, appendages, of which several pairs occur on the abdominal somites of many crustaceans. They are used as fins in swimming.
Example Sentences:
(1) Mechanosensory stimulation of an abdominal swimmeret initiates a fictive extension which includes flexion inhibition.
(2) The strongest extension response was produced at 2 Hz which falls within the normal range of swimmeret beating in intact lobsters.
(3) Feathered hair sensilla fringe both rami of the lobster (Homarus americanus) swimmeret.
(4) Proof that PTX acts by binding the GABA receptor was obtained by observing that the addition of GABA or muscimol to preparations pretreated with PTX did not affect either spontaneous or swimmeret evoked activities, or intracellular potential amplitudes.
(5) The sensilla on the male and female second swimmerets are sexually dimorphic.
(6) Evidence from extracellular analyses suggested that single interneurons of the abdominal nerve cord could produce motor outputs in both the swimmeret and the abdominal positioning systems.
(7) Localized tactile stimulation of the swimmeret surface with a mechanical probe usually generated flexion inhibition where the flexor inhibitor (f5) was activated while the small and medium flexor excitors were inhibited.
(8) DL-Octopamine inhibits the swimmeret system, both when the system is spontaneously active and when it has been excited by proctolin.
(9) Physiological experiments in which RPCH was perfused into the ganglia of isolated nerve cords showed that RPCH modulated the swimmeret rhythm.
(10) A study has been made of the interrelations between rhythmical exopodite beating in different larval stages and swimmeret beating in poast-larval stages of the lobster Homarus gammarus.
(11) Female swimmerets contain many long "smooth hairs" (long simple setae) on the coxa and rami.
(12) The membrane potential of interneuron IA oscillated in phase with the swimmeret rhythm, a motor pattern generated in each of these ganglia, because the neuron received postsynaptic potentials in phase with the rhythm.
(13) Differences emerge in the performance of larval exopodites and post-larval swimmerets (table 6b), although the possibility cannot be excluded that the larval exopodite oscillator in some way influences the developing action of the post-larval swimmeret system.
(14) The response properties of both types of hypodermal mechanoreceptors imply that they are activated during the characteristic beating movements of the swimmerets.
(15) The swimmerets in the abdomen of the lobster Homarus americanus are paired external appendages whose back and forth propulsive movements are brought about largely by a group of power and return stroke muscles located in the lateral abdominal cavity.
(16) None of the dual output neurons examined influenced the swimmeret motoneurons directly.
(17) Gas chromatographic analysis of hepatopancreas and swimmeret muscle tissue of dead and dying crabs revealed total DDT residue concentrations as high as 39.0 ppm and 1.43 ppm, respectively.
(18) Phentolamine also blocks inhibition of the swimmeret system by inhibitory command interneurons.
(19) The sensory response to hair displacement was characterized by recording afferent impulses extracellularly from the swimmeret sensory nerve while deflecting sensilla with a rigidly-coupled probe or controlled water movements.
(20) In nerve cords that were spontaneously producing the swimmeret rhythm, RPCH lengthened both the period and the duration of bursts of action potentials, but did not alter the phase relationships between bursts in different segments.
Telson
Definition:
(n.) The terminal joint or movable piece at the end of the abdomen of Crustacea and other articulates. See Thoracostraca.
Example Sentences:
(1) By quantitative sodium dodecyl sulfate-polyacrylamide gel electrophoresis, paramyosin:myosin heavy chain molecular ratios were calculated for three molluscan muscles:Aequipecten striated adductor, Mercenaria opaque adductor, and Mytilus anterior byssus retractor; and four arthropodan muscles:Limulus telson, Homarus slow claw.
(2) Small angle x-ray diffraction patterns were recorded from isometrically contracting Limulus (horseshoe crab) telson levator muscle using a multiwire proportional-area detector on the storage ring DORIS.
(3) In their absence, the telson and acron are not formed.
(4) The recessive zygotic lethal mutation tailless maps to region 100A5,6-B1,2 at the tip of the right arm of chromosome 3, and results in shortened pharyngeal ridges in the head skeleton of the mature embryo and the elimination of the eighth abdominal segment and telson.
(5) When any afferent nerve from the telson was stimulated, both telson FIs showed an additional fast-rising, short-latency (1.4 ms) PSP, which preceded the slow component.
(6) Egyptian scorpion venom was collected by electrical stimulation of the telson.
(7) These studies suggest the following model: for the anteroposterior axis of the embryo, three groups of maternal genes define three largely independent systems that determine (1) the anterior segmented region of head and thorax, (2) the posterior segmented region of the abdomen, and (3) the terminal non-segmented regions of acron and telson.
(8) Here we present evidence that strongly suggests that the well-documented phenomenon of A-band shortening in Limulus telson muscle is activation dependent and reflects fragmentation of thick filaments at their ends.
(9) The neutralizing capacity of these antisera are compared: it appears that a telson extract can be used instead of the crude venom to produce an efficient antiserum.
(10) No generalization to a spatial displacement of the stimulus was obtained, although a visually elicited telson reflex had been shown to demonstrate a cross-optic generalization.
(11) Incubation of long (greater than or equal to 4.0 microns) thick filaments, separated from Limulus telson muscle under relaxing conditions, with either intact MLCK in the presence of Ca2+ and calmodulin, or Ca2(+)-independent MLCK obtained by brief chymotryptic digestion (Walsh, M. P., R. Dabrowska, S. Hinkins, and D. J. Hartshorne.
(12) The musculature of the telson of Limulus polyphemus L. consists of three dorsal muscles: the medial and lateral telson levators and the telson abductor, and one large ventral muscle; the telson depressor, which has three major divisions: the dorsal, medioventral, and lateroventral heads.
(13) Muscle correlates of reflex telson movement were recorded in intact Limulus (horseshoe crab) preparations with chronically implanted microelectrodes.
(14) Of the muscles in this study, Limulus telson levator is the only one for which the antiparamyosin staining pattern has been previously reported.
(15) The motor circuits that control telson flexion in the crayfish (Procambarus clarkii) include a curiously arranged sub-circuit: a premotor 'command' neuron excites a motor neuron via a trisynaptic pathway, but also inhibits (and prevents firing of) the motor neuron via a shorter latency pathway (Kramer et al.
(16) The formation of the telson in the Drosophila embryo, which encompasses all structures posterior to abdominal segment 7, is under the control of the "terminal class" genes.
(17) Interneurons activated by mechanosensory hairs on the crayfish telson respond selectively to directional displacements of the medium; the directions of maximum sensitivity lie 180 degrees apart in approximately the rostrocaudal plane, corresponding to the directional sensitivities of the two populations of primary afferent neurons.
(18) Calcium activation of detergent-skinned fiber bundles of Limulus telson muscle results in large decreases in A-band (from 5.1 to 3.3 microns) and thick filament (from 4.1 to 3.3 microns) lengths and the release of filament end fragments.
(19) The formation of the unsegmented terminal regions of the Drosophila larva, acron and telson requires the function of at least five maternal genes (terminal genes class).
(20) The implications of the observed heterogeneity of fibre types is discussed with reference to previously reported phenomena in Limulus telson muscle, including changes in length of thick filaments on fibre stimulation and the shape of the length-tension curve obtained from fibre bundles.