Behavioural Physiology of the Colonial Hydroid Obelia

1971 ◽  
Vol 54 (3) ◽  
pp. 707-721
Author(s):  
JAMES G. MORIN ◽  
IAN M. COOKE
Keyword(s):  
Rate Constant ◽  
Mechanical Stimulation ◽  
Mouth Opening ◽  
Physiological Mechanisms ◽  
Variable Intensity ◽  
Frequency Coupling ◽  
Constant Shape ◽  
Degree Of Coupling ◽  
Colonial Hydroid ◽  
Obelia Geniculata

1. Electrical, mechanical or chemical (KC1) stimuli produce similar luminescent flashing in Obelia geniculata. Hydranth withdrawal also occurs upon electrical or mechanical stimulation. 2. Luminescent flashes in response to individual stimuli occur in bursts. The first few flashes of the burst facilitate in intensity and then decline. Successive flashes within each burst show a constant shape and duration but a variable intensity. 3. The decay phase of the luminescent flash has a rate constant of 50 s-1 at 20±1 °C and 29 s-1 at 127plusmn; 1 °C. From these figures an energy of activation of about 12 kcal can be calculated. 4. Upon stimulation, an excitation system, the luminescent potential (LP) system, initiates the luminescent effector flashing. The LPs are monophasic, positive, and slow (duration about 120 ms) and are distinguishable from contraction potentials (KPs) mouth-opening potentials (MOPs) and tentacle contraction potentials (TKPs). LPs are all-or-none, non-decremental, through-conducting (at least over short distances) and show non-polar spread. 5. The LP systems can drive the KPs at the LP frequency. Coupling varies from none to very tight, and the degree of coupling is determined at each hydranth. 6. Several other campanulariids and probably most, if not all, luminescent hydroids possess similar physiological mechanisms for controlling stimulus-initiated luminescent responses.

Behavioural Physiology of the Colonial Hydroid Obelia

1971 ◽  
Vol 54 (3) ◽  
pp. 689-706
Author(s):  
JAMES G. MORIN ◽  
IAN M. COOKE
Keyword(s):  
Mouth Opening ◽  
The Other ◽  
Behavioural Responses ◽  
Electrical Potentials ◽  
External Stimuli ◽  
Colonial Hydroid ◽  
Obelia Geniculata

1. Spontaneous electrical potentials from Obelia geniculata hydranths were recorded using fine-tipped suction electrodes. 2.The primary behavioural responses of the hydranths were observed and correlated with specific electrical potentials: the contraction potential (KP) associated with hydranth withdrawal, the mouth-opening potential (MOP) associated with mouth opening, and the tentacle contraction potential (TKP) associated with oral flexion of individual tentacles. 3. KPs occurred in rhythmic bursts while the TKP and MOP responses were infrequent and non-rhythmic. 4. Two other species, O. longissima and Gonothyraea loveni, were shown to produce the same three types of potentials with corresponding behavioural responses. 5. The MOP activity may occasionally drive the KP responses within a hydranth, but the coupling is very loose. None of the other possible interactions within a hydranth was observed. 6. No interaction of any of the potentials between adjacent hydranths was found in the absence of external stimuli. 7. It seems likely that the KPs in Obelia are homologous with the contraction potential (CP) in Hydra and the hydranth potential (HP)) in Tubularia. MOP and TKP activity do not show apparent homologies with potentials of the other hydroids Hydra, Tubularia and Cordylophora.

Reproduction of the colonial hydroid Obelia geniculata (L., 1758) (Cnidaria, Hydrozoa) in the White Sea

Hydrobiologia ◽  
2004 ◽  
Vol 530-531 (1-3) ◽  
pp. 383-388 ◽  
Author(s):  
Sergei A. Slobodov ◽  
Nickolai N. Marfenin
Keyword(s):  
White Sea ◽  
The White Sea ◽  
Colonial Hydroid ◽  
Obelia Geniculata

Mechanical stimulation of human BON cells: Gαq involvement in 5-HT release

2001 ◽  
Vol 120 (5) ◽  
pp. A83-A83
Author(s):  
M KIM ◽  
N JAVED ◽  
F CHRISTOFI ◽  
H COOKE
Keyword(s):  
Mechanical Stimulation ◽  
Bon Cells ◽  
Stimulation Of

Functional Properties of p-Anisoylated Plasmin-Staphylokinase Complex

1993 ◽  
Vol 70 (02) ◽  
pp. 326-331 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
R A G Smith ◽  
D Collen
Keyword(s):  
Human Plasma ◽  
Rate Constant ◽  
Time Course ◽  
Bolus Injection ◽  
Similar Rate ◽  
Clot Lysis ◽  
Lag Phase ◽  
Plasma Clot ◽  
Rapid Clearance ◽  
Stoichiometric Complex

SummaryThe kinetic and fibrinolytic properties of a reversibly acylated stoichiometric complex between human plasmin and recombinant staphylokinase (plasmin-STAR complex) were evaluated. The acylation rate constant of plasmin-STAR by p-amidinophenyl-p’-anisate-HCI was 52 M-1 s-1 and its deacylation rate constant 1.2 × 10-4 s-1 (t½ of 95 min) which are respectively 50-fold and around 3-fold lower than for the plasmin-streptokinase complex. The acylated complex was stable as evidenced by binding to lysine-Sepharose. However, following an initial short lag phase, the acylated plasmin-STAR complex activated plasminogen at a similar rate as the unblocked complex, whereas the acylated plasmin-streptokinase complex did not activate plasminogen. These findings indicate that STAR, unlike streptokinase, dissociates from its acylated complex with plasmin in the presence of excess plasminogen. In agreement with this hypothesis, the time course of the lysis of a 125I-fibrin labeled plasma clot submerged in citrated human plasma, is similar for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR (50% clot lysis in 2 h requires 12 nM of each agent). The plasma clearances of STAR-related antigen following bolus injection in hamsters were 1.0 to 1.5 ml/min for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR, as a result of short initial half-lives of 2.0 to 2.5 min.The dissociation of the anisoylated plasmin-STAR complex and its consequent rapid clearance suggest that it has no apparent advantages as compared to free STAR for clinical thrombolysis.

The effect of low magnitude mechanical stimulation (LMMS) on bone density in patients with Rett syndrome: A pilot and feasibility study

2014 ◽  
Vol 7 (2) ◽  
pp. 167-178 ◽  
Author(s):  
Sarah Y. Afzal ◽  
Anna R. Wender ◽  
Mary D. Jones ◽  
Ellen B. Fung ◽  
Elaine L. Pico
Keyword(s):  
Bone Density ◽  
Rett Syndrome ◽  
Feasibility Study ◽  
Mechanical Stimulation ◽  
Low Magnitude

Use of Flexible Materials with a Novel Pressure Driven Equibiaxial Cell Stretching Device for Mechanical Stimulation of Single Mammalian Cells

2003 ◽  
Vol 773 ◽  
Author(s):  
James D. Kubicek ◽  
Stephanie Brelsford ◽  
Philip R. LeDuc
Keyword(s):  
Cell Fate ◽  
Mechanical Stimulation ◽  
Mammalian Cells ◽  
Cellular Response ◽  
Single Cells ◽  
Complex Nature ◽  
Cellular Behavior ◽  
Cell Stretching ◽  
Stimulation Of ◽  
Pressure Driven

AbstractMechanical stimulation of single cells has been shown to affect cellular behavior from the molecular scale to ultimate cell fate including apoptosis and proliferation. In this, the ability to control the spatiotemporal application of force on cells through their extracellular matrix connections is critical to understand the cellular response of mechanotransduction. Here, we develop and utilize a novel pressure-driven equibiaxial cell stretching device (PECS) combined with an elastomeric material to control specifically the mechanical stimulation on single cells. Cells were cultured on silicone membranes coated with molecular matrices and then a uniform pressure was introduced to the opposite surface of the membrane to stretch single cells equibiaxially. This allowed us to apply mechanical deformation to investigate the complex nature of cell shape and structure. These results will enhance our knowledge of cellular and molecular function as well as provide insights into fields including biomechanics, tissue engineering, and drug discovery.

Morphological and Photodecomposition Rate Constant Study of PVC Films Doped with Sulfadiazine Tin(IV) Complexes

2020 ◽  
Vol 14 (2) ◽  
pp. 88
Author(s):  
Emad Yousif
Keyword(s):  
Radiation Exposure ◽  
Uv Radiation ◽  
Rate Constant ◽  
Experimental Results

This article focus on the calculation of photodecomposition rate constant of PVC films that containing sulfadiazine tin(IV) complexes 1-3 as photostabilzers during UV radiation exposure. This constant calculated as a method for evaluating the efficiency of sulfadiazine tin(IV) complexes 1-3 when used as a PVC photostabilizers after 300 hours of irradiation. The experimental results showed that sulfadiazine tin(IV) complexes 1-3 have reduced the rate of photodecomposition constant value of PVC films significantly with comparison to PVC (blank).

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