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.

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.

scholarly journals SPECIFIC NERVE IMPULSES FROM GUSTATORY AND TACTILE RECEPTORS IN CATFISH

1933 ◽  
Vol 16 (4) ◽  
pp. 685-693 ◽  
Author(s):  
Hudson Hoagland
Keyword(s):  
Facial Nerve ◽  
Bilateral Symmetry ◽  
Great Sensitivity ◽  
Gasserian Ganglion ◽  
Mechanical Stimuli ◽  
Tactile Receptors ◽  
Meat Juice ◽  
Cells Of Origin ◽  
Set Up ◽  
Sense Modalities

1. Receptors in the lips and barbels of the catfish Ameiurus nebulosus Les. are very sensitive to mechanical stimuli, giving large rapid (A-type) impulses in fibers of the facial nerve in response to touching the receptive surfaces and to movements of the water in which the preparation is immersed. 2. The great sensitivity of the barbels and lips to currents of water and the bilateral symmetry of the distribution of sensitivity of the facial nerve may serve as a basis for observed rheotropic orientation in the catfish. 3. Acetic acid, NaCl, and meat juice, dissolved in the water bathing the barbels and lips, set up impulses of very small and barely detectable potential in the fibers of the facial nerve. 4. It is suggested that the specificity of impulses for the two sense modalities may be correlated with the large size of the cells of origin of the axons in the Gasserian ganglion supplying tactile receptors and the small size of the cells of origin in the geniculate ganglion sending axons to taste-buds.

scholarly journals Germinant Synergy FacilitatesClostridium difficileSpore Germination under Physiological Conditions

mSphere ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Travis J. Kochan ◽  
Michelle S. Shoshiev ◽  
Jessica L. Hastie ◽  
Madeline J. Somers ◽  
Yael M. Plotnick ◽  
...  
Keyword(s):  
Amino Acids ◽  
Clostridium Difficile ◽  
Spore Germination ◽  
Bile Salts ◽  
Gi Tract ◽  
Infectious Diarrhea ◽  
Content Type ◽  
Increased Risk ◽  
Calcium Reabsorption

ABSTRACTClostridium difficileis a Gram-positive obligate anaerobe that forms spores in order to survive for long periods in the unfavorable environment outside a host.C. difficileis the leading cause of nosocomial infectious diarrhea worldwide.C. difficileinfection (CDI) arises after a patient treated with broad-spectrum antibiotics ingests infectious spores. The first step inC. difficilepathogenesis is the metabolic reactivation of dormant spores within the gastrointestinal (GI) tract through a process known as germination. In this work, we aim to elucidate the specific conditions and the location within the GI tract that facilitate this process. Our data suggest thatC. difficilegermination occurs through a two-step biochemical process that is regulated by pH and bile salts, amino acids, and calcium present within the GI tract. Maximal germination occurs at a pH ranging from 6.5 to 8.5 in the terminal small intestine prior to bile salt and calcium reabsorption by the host. Germination can be initiated by lower concentrations of germinants when spores are incubated with a combination of bile salts, calcium, and amino acids, and this synergy is dependent on the availability of calcium. The synergy described here allows germination to proceed in the presence of inhibitory bile salts and at physiological concentrations of germinants, effectively decreasing the concentrations of nutrients required to initiate an essential step of pathogenesis.IMPORTANCEClostridium difficileis an anaerobic spore-forming human pathogen that is the leading cause of nosocomial infectious diarrhea worldwide. Germination of infectious spores is the first step in the development of aC. difficileinfection (CDI) after ingestion and passage through the stomach. This study investigates the specific conditions that facilitateC. difficilespore germination, including the following: location within the gastrointestinal (GI) tract, pH, temperature, and germinant concentration. The germinants that have been identified in culture include combinations of bile salts and amino acids or bile salts and calcium, butin vitro, these function at concentrations that far exceed normal physiological ranges normally found in the mammalian GI tract. In this work, we describe and quantify a previously unreported synergy observed when bile salts, calcium, and amino acids are added together. These germinant cocktails improve germination efficiency by decreasing the required concentrations of germinants to physiologically relevant levels. Combinations of multiple germinant types are also able to overcome the effects of inhibitory bile salts. In addition, we propose that the acidic conditions within the GI tract regulateC. difficilespore germination and could provide a biological explanation for why patients taking proton pump inhibitors are associated with increased risk of developing a CDI.

scholarly journals The Effects of Possible Contamination on the Radiocarbon Dating of the Dead Sea Scrolls II: Empirical Methods to Remove Castor Oil and Suggestions for Redating

Radiocarbon ◽  
2009 ◽  
Vol 51 (3) ◽  
pp. 1005-1022 ◽  
Author(s):  
Kaare Lund Rasmussen ◽  
Johannes van der Plicht ◽  
Gregory Doudna ◽  
Frederik Nielsen ◽  
Peter Højrup ◽  
...  
Keyword(s):  
Amino Acids ◽  
Castor Oil ◽  
Radiocarbon Dating ◽  
Soxhlet Extraction ◽  
Dead Sea Scrolls ◽  
Dead Sea ◽  
Empirical Methods ◽  
Advantages And Disadvantages ◽  
The Dead ◽  
East Jerusalem

While kept at the Rockefeller Museum in East Jerusalem, many Dead Sea Scroll fragments were exposed to castor oil by the original team of editors in the course of cleaning the parchments. Castor oil must be regarded as a serious contaminant in relation to radiocarbon dating. If modern castor oil is present and is not removed prior to dating, the 14C dates will be skewed artificially towards modern values. In Rasmussen et al. (2001), it was shown that the standard AAA pretreatment procedure used in the 2 previous studies dating Dead Sea Scroll samples (Bonani et al. 1992; Jull et al. 1995) is not capable of removing castor oil from parchment samples. In the present work, we show that it is unlikely that castor oil reacts with the amino acids of the parchment proteins, a finding which leaves open the possibility of devising a cleaning method that can effectively remove castor oil. We then present 3 different pretreatment protocols designed to effectively remove castor oil from parchment samples. These involve 3 different cleaning techniques: extraction with supercritical CO2, ultrasound cleaning, and Soxhlet extraction—each with their own advantages and disadvantages. Our data show that the protocol involving Soxhlet extraction is the best suited for the purpose of decontaminating the Dead Sea Scrolls, and we recommend that this protocol be used in further attempts to 14C date the Dead Sea Scrolls. If such an attempt is decided on by the proper authorities, we propose a list of Scroll texts, which we suggest be redated in order to validate the 14C dates done earlier by Bonani et al. (1992) and Jull et al. (1995).

scholarly journals EFFECT OF BIOLOGICALLY ACTIVE SUBSTANCES FORMED BY BACCILUS COAGULANS TI ON THE GROWTH OF CROPS

2013 ◽  
Vol 17 (2) ◽  
pp. 53-60
Author(s):  
Tatiana Lisitskaya ◽  
Tatiana Trosheva
Keyword(s):  
Amino Acids ◽  
Plant Biomass ◽  
Bacillus Coagulans ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Submerged Cultivation ◽  
Peptone Medium ◽  
Active Substances ◽  
Stimulation Of

Abstract The influence of cultural liquid of bacteria, Bacillus coagulans TI on the growth of several crops are studded. It was established that during the submerged cultivation on glucose-peptone medium these bacteria form gibberellins and amino acids. Pre-sowing treatment of seeds with diluted cultural liquid causes the stimulation of plants growth and improves the quality of plant biomass.

scholarly journals Zinc(II) Complexes with Amino Acids for Potential Use in Dermatology: Synthesis, Crystal Structures, and Antibacterial Activity

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 951 ◽  
Author(s):  
Michał Abendrot ◽  
Lilianna Chęcińska ◽  
Joachim Kusz ◽  
Katarzyna Lisowska ◽  
Katarzyna Zawadzka ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antibacterial Activity ◽  
Antibacterial Properties ◽  
Antimicrobial Properties ◽  
X Ray Diffraction ◽  
Organic Zinc ◽  
Counter Ions ◽  
Open Issue ◽  
Potential Use ◽  
Active Substances

The multifunctional profile of Zn2+ has influenced its great popularity in various pharmaceutical, food, and cosmetic products. Despite the use of different inorganic and organic zinc derivatives, the search for new zinc-containing compounds with a safer skin profile still remains an open issue. The present paper describes the synthesis, structural characterization, and antibacterial activity of zinc(II) complexes with proteinogenic amino acids as potential candidates for dermatological treatments. The obtained complexes are of the general formula [Zn(AA)2], where AA represents an amino acid (L-Glu, Gly, L-His, L-Pro, L-Met, and L-Trp). Their synthesis was designed in such a way that the final bis(aminoacidate) zinc(II) complexes did not contain any counter-ions such as Cl−, NO3−, or SO42− that can cause some skin irritations. The chemical structure and composition of the compounds were identified by 1H NMR spectroscopy and elemental analysis, and four were also characterized by single-crystal X-ray diffraction. The Hirshfeld surface analysis for the Zn2+ metallic center helped to determine its coordination number and geometry for each complex. Finally, the antibacterial properties of the complexes were determined with respect to three Gram-positive strains, viz. Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, and Streptococcus pyogenes ATCC 19615, and two Gram-negative bacteria, viz. Escherichia coli ATCC 25992 and Pseudomonas aeruginosa ATCC 27853, and were compared with the activity of zinc 2-pirrolidone 5-carboxylate (ZnPCA), commonly applied in dermatology. It was found that the Zn(II) complexes with methionine and glycine exhibited a higher antibacterial activity than the tested standard, and the antimicrobial properties of complex with Trp were satisfactory. The results of the antimicrobial activity examination allow us to postulate that the obtained zinc complexes might become new active substances for use in dermatological products.

Sign in / Sign up

Export Citation Format

Share Document