scholarly journals The Excitation of Nematocysts

1942 ◽  
Vol 19 (3) ◽  
pp. 294-310 ◽  
Author(s):  
C. F. A. PANTIN
Keyword(s):  
Mechanical Stimulus ◽  
Solid Food ◽  
Natural Food ◽  
Mechanical Stimuli ◽  
Contact Sensitization ◽  
Anemonia Sulcata ◽  
Spread Of Excitation ◽  
Surface Active ◽  
Contact Discharge ◽  
Active Substances

1. The nature of the stimulus which causes discharge of the cnidae (nematocysts and spirocysts) in the tentacles of Anemonia sulcata has been studied. 2. The cnidoblasts behave as independent effectors. Contact with solid food or electric stimuli cause only local discharge. Repetitive electric stimulation at various frequencies causes spread of excitation far down the nerve net of the tentacle but the cnida discharge remains localized under the stimulating electrode. There is no physiological evidence for any connexion ofcnidoblasts with the nervous system. 3. The stimulus to the cnidoblast is primarily due to direct mechanical contact. Discharge is easily effected by solid food. It can also be effected by inert solids provided the mechanical stimulus is sufficiently intense. 4. The normal stimulus to the cnidoblast is not a directly chemical one. Most food solutions and solutions of food derivatives do not cause a discharge. Some strong food solutions cause a few scattered cnidae to discharge. This differs from the intense local discharge to solid food. 5. Immersion in solutions of certain surface-active substances, such as the lower fatty acids, bile salts and saponin, causes an immediate general discharge of all the cnidae. This differs from the normal discharge to solid food. 6. Although natural food solutions do not normally cause a discharge, the cnidae are easily discharged by contact when they are present. That is, food solutions sensitize the cnidoblasts to mechanical stimuli. 7. The sensitizing substance is not protein. But it is strongly adsorbed on to protein. It cannot be extracted with ethyl ether. But it can be extracted with ethyl alcohol or acetone. Alcohol extracts of food are very active in sensitizing the cnidoblasts to mechanical disturbance. 8. Water insoluble foods can sensitize cnidoblasts with which they come in contact. Sensitization by contact is almost instantaneous. It is suggested that normally sensitization is due to some surface active lipoid directly transferred to the cnidoblast by contact.

Rapid Contractions and Associated Potentials in a Sand-Dwelling Anemone

1969 ◽  
Vol 51 (2) ◽  
pp. 513-528
Author(s):  
PETER E. PICKENS
Keyword(s):  
Maximum Size ◽  
Mechanical Stimulus ◽  
Retractor Muscle ◽  
Mechanical Stimuli ◽  
Nerve Impulses ◽  
Electrical Potentials ◽  
Spread Of Excitation ◽  
Electrical Stimuli ◽  
Withdrawal Response ◽  
Muscle Potential

1. Two kinds of electrical potentials can be recorded from the surface of the. retractor muscle of the anemone, Calamactis, during rapid contraction. These are large muscle action potentials and smaller pulses which are thought to be nerve spikes The latter resemble nerve impulses of higher organisms in that they are all-or-none and of short duration. 2. A nerve spike follows each of a pair of electrical stimuli, but the muscle potential and contraction occur only after the second shock, indicating that facilitation is required at the neuromuscular junction. 3. The size of the muscle potential and of the contraction are correlated with the interval between paired electrical stimuli. Maximum size is reached when stimuli are zoo msec. apart even though the minimum effective interval is 30 msec. 4. A muscle potential precedes contraction only along the upper part of the retractor muscle and this is the part that contracts rapidly during the withdrawal response. The lower retractor does not contract. 5. Conduction velocity along the upper retractor is higher than along the lower. The histological correlate of rapid conduction is a nerve net with large, long, longitudinally oriented fibres. 6. The refractory period of the conducting system of the upper retractor is shorter than that of the lower retractor. Consequently, spread of excitation toward the aboral end is limited if paired stimuli are further apart than 250-300 msec. 7. A mechanical stimulus which is just strong enough to elicit a withdrawal response evokes a single muscle potential of maximum size, suggesting that two nerve impulses closer together than 200 msec. precede the muscle potential. Stronger mechanical stimuli evoke a burst of muscle potentials.

scholarly journals The Stimulus to Feeding in Anemonia Sulcata

1943 ◽  
Vol 20 (1) ◽  
pp. 6-13
Author(s):  
C. F. A. PANTIN ◽  
A. M. P. PANTIN
Keyword(s):  
Amino Acids ◽  
Bile Salts ◽  
Soxhlet Extraction ◽  
Great Sensitivity ◽  
Mechanical Stimuli ◽  
Feeding Response ◽  
Anemonia Sulcata ◽  
Set Up ◽  
Natural Foods ◽  
Active Substances

1. Feeding can be initiated in Anemonia sulcata by mechanical, chemical or electrical stimulation of the tentacles provided the stimulus sets up sufficiently prolonged excitation. Owing to rapid adaptation, mechanical stimuli rarely set up enduring excitation and inert objects are therefore usually rejected. Chemical stimuli set up prolonged excitation and food objects are therefore usually accepted. A series of electrical stimuli can produce rejection or feeding according to whether it is brief or prolonged. 2. The sensitivity of the tentacles varies greatly a different foods. It is greatest to animal foods. There is great sensitivity to certain kinds of mucus. 3. The active substances of natural foods are closely associated with protein. They fail to pass through a membrane which retains colloids. A feeding reaction can be obtained to food substances which appear to be insoluble in water. 4. Though the active substances of many natural foods are not in free solution, soluble derivatives of proteins, such as peptones and amino acids cause a feeding reaction. With pure proteins, the response of the cnida diminished. With amino acids, there is no cnida response. From this it follows that increased mechanical contact due to cnida discharge is not essential for excitation of the feeding response. 5. Fat, such as tristearin, and ethereal extracts of food are without effect. Alcoholic Soxhlet extraction of food yields a substance which causes the food reaction. Carbohydrates are without effect except in the case of glycogen, the action of which may be due to impurities. 6. The lower fatty acids, quinine and bile salts produce a withering contraction of the tentacles which differs from the response of the latter to food. The effect can be produced by prolonged electrical excitation at a higher frequency than that required for the feeding response and is therefore probably due to excessive stimulation. 7. The mouth responds to a greater variety of chemcial stimuli than the tentacles. The relative sensitivity of these organs to different chemcial stimuli is not the same, but for most agents the mouth is the more sensitive. Quinine, histamine and 10% bile salts excite the musculature of the mouth directly. 8. The range of chemical sensitivity in different coelenterates is discussed.

Surface Active Substances in the Chinchilla Tubotympanum: a Biochemical Study

1991 ◽  
Vol 111 (3) ◽  
pp. 1097-1104
Author(s):  
James Coticchia ◽  
Frederick Heiselman ◽  
Raouf Gharbo ◽  
Thomas Demaria ◽  
David Lim
Keyword(s):  
Biochemical Study ◽  
Surface Active ◽  
Active Substances

Influence of surface active substances on AKD sizing

2005 ◽  
Vol 20 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Elisa Zeno ◽  
Bruno Carré ◽  
Evelyne Mauret
Keyword(s):  
Surface Active ◽  
Active Substances

scholarly journals The possible role of the Surface Active Substances (SAS) in the airborne transmission of SARS-CoV-2

2021 ◽  
pp. 111215
Author(s):  
Irena Ciglenečki ◽  
Palma Orlović-Leko ◽  
Kristijan Vidović ◽  
Viša Tasić
Keyword(s):  
Airborne Transmission ◽  
Surface Active ◽  
Active Substances

The kinetics of the penetration of some representative anthelmintics and related compounds into Ascaris lumbricoides var. suis

Parasitology ◽  
1949 ◽  
Vol 39 (3-4) ◽  
pp. 281-290 ◽  
Author(s):  
A. R. Trim
Keyword(s):  
Ascaris Lumbricoides ◽  
Homogeneous Layer ◽  
Outermost Layer ◽  
Basic Group ◽  
Rate Of Penetration ◽  
Surface Active ◽  
Main Barrier ◽  
Kinetics Of ◽  
Related Compounds ◽  
Active Substances

1. The rate of penetration of some representative drugs into Ascaris lumbricoides var. suis has been measured.2. The series of 4-n-alkyl resorcinols shows a typical homologous series effect.3. l-Nicotine penetrates relatively slowly.4. Its rate of penetration is greatly influenced by the extent of dissociation of its methyl pyrrolidine basic group.5. The rate of penetration of nicotine is greatly accelerated in the presence of some surface active substances.6. Chloroform is the most rapidly penetrating substance studied, and its penetration is not significantly influenced by the presence of proteins, carbohydrates and fats and their products of digestion.7. An analysis of the experimental results shows that the outermost layer of the cuticle of Ascaris is probably the main barrier to penetration. It behaves as if it were a thin; homogeneous layer of lipoid.8. The significance of these results in the study of anthelmintics is assessed.

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