scholarly journals Factors Influencing Facilitation in Actinozoa. The Action of Certain Ions

1940 ◽  
Vol 17 (1) ◽  
pp. 61-73
Author(s):  
D. M. ROSS ◽  
C. F. A. PANTIN
Keyword(s):  
Carbon Dioxide ◽  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Sea Water ◽  
Hydrogen Ion ◽  
Excitation Process ◽  
Nervous Impulse ◽  
Excess Calcium ◽  
Main Effect ◽  
Sensitization Process

1. The anaesthetic effects of carbon dioxide and magnesium added to sea water on Calliactis parasitica and Metridium senile have been studied. Magnesium first paralyses sense organs, but the main effect of both magnesium and carbon dioxide is a depression of neuromuscular facilitation. This prevents conduction of nervous impulses to the muscles in a way analogous to curarization of vertabrate skeletal muscle. 2. The chief effects of excess calcium, potassium and the hydrogen ion are increases in the size of the facilitated response to stimulation. The responses under potassium and the hydrogen ion are greatly prolonged and resemble the veratrine contracture of vertebrate skeletal muscle. 3. All the substances studied exert their chief effects at the neuromuscular junction. Analysis of their mode of action indicates that neuromuscular transmission in anemones involves two distinct processes, a process of excitation and a process of sensitization of the neuromuscular junction without which excitation of the muscle by the nervous impulse cannot be effective. This view is confirmed by examination of the relation of the size of the responses in normal animals to successive stimuli. The nature of the sensitization process and of the excitation process is discussed.

scholarly journals REGULATION OF THE HYDROGEN ION CONCENTRATION AND ITS RELATION TO METABOLISM AND RESPIRATION IN THE STARFISH

1926 ◽  
Vol 10 (2) ◽  
pp. 345-358 ◽  
Author(s):  
Laurence Irving
Keyword(s):  
Carbon Dioxide ◽  
Sea Water ◽  
Carbon Dioxide Production ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Coelomic Fluid ◽  
Vital Function ◽  
Hydrogen Ion Concentration ◽  
Optimum Ph ◽  
Patiria Miniata

The normal reaction of the cœlomic fluid in Patiria miniata and Asterias ochraceus is pH 7.6, and of the cæca, 6.7, compared with sea water at 8.3, all without salt error correction. A medium at pH 6.7–7.0 is optimum for the cæca for ciliary survival and digestion of protein, and is maintained by carbon dioxide production. The optimum pH found for carbon dioxide production is a true one for the effect of hydrogen ion concentration on the tissue. It does not represent an elimination gradient for carbon dioxide. Because the normal excised cæca maintain a definite hydrogen ion concentration and change their internal environment toward that as an optimum during life, there exists a regulatory process which is an important vital function.

The Absorption of Oxygen by Plaice Eggs

1928 ◽  
Vol 5 (3) ◽  
pp. 177-184
Author(s):  
S. T. BURFIELD
Keyword(s):  
Carbon Dioxide ◽  
Large Volume ◽  
Marked Effect ◽  
Sea Water ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Oxygen Absorption ◽  
Closed Volume ◽  
Hydrogen Ion Concentration ◽  
Rate Of Absorption

1. The rate of oxygen absorption by plaice eggs, contained in a closed volume of sea water, falls when the eggs and water are allowed to remain relatively quiescent. This fall takes place even when a large volume of water is used. 2. It has been shown that small changes in the partial pressure of dissolved oxygen do not appreciably affect the rate of absorption, so that this is not the factor concerned in the fall. 3. The rate of oxygen absorption in a closed volume of sea water does not fall if the eggs be frequently moved. 4. The removal of eggs to a closed volume of fresh sea water at the end of a period prevents the rate of absorption from falling during a second equal period. 5. The removal of eggs to a closed volume of "used" sea water at the end of a period causes the rate of absorption to fall during a second equal period. 6. The addition of urea in small quantities to the sea water has no effect on oxygen absorption. 7. The addition of carbon dioxide to the sea water has a marked effect in lowering the rate of oxygen absorption, and the accumulation of excreted carbon dioxide is probably the factor causing the fall in absorption mentioned under paragraphs 1 and 5. 8. This effect is possibly directly due to the alteration in the hydrogen ion concentration produced by the carbon dioxide. 9. The Respiratory Quotient of young plaice eggs is about .75.

scholarly journals The Hydrogen Ion Concentration of Sea Water in its Biological Relations

1922 ◽  
Vol 12 (4) ◽  
pp. 717-771 ◽  
Author(s):  
W. R. G. Atkins
Keyword(s):  
Carbon Dioxide ◽  
Methyl Orange ◽  
Hydrochloric Acid ◽  
River Water ◽  
Sea Water ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Water ◽  
End Points ◽  
Hydrogen Ion Concentration

It has long been known that sea water is alkaline and numerous determinations of its alkalinity have been made. The method adopted was the usual one for mixtures of carbonates and bicarbonates, or some modification of it. Those waters which give no colour with phenolphthalein contain bicarbonate only, but for the most part ocean waters have a small amount of carbonate also. Owing to the presence of larger amounts of carbonates and bicarbonates the reaction of sea water is more stable than that of rain or river water, inasmuch as it has a greater alkaline reserve which acts as a “buffer.” The significance of this has been pointed out by Moore, Prideaux, and Herdman (1915) and by other workers. The measurement of alkalinity was carried out by the above named using N/100 hydrochloric acid and titrating to the end points with phenol phthalein and methyl orange. The results are recorded in cubic centimetres of centinormal acid per 100 c.c. of sea water; this is convenient as it is what is measured directly, but others adopt the perhaps more rational notation of milligram equivalents of hydroxyl per litre (Buch, 1914). One cubic centimetre of N/100 acid per 100 c.c. corresponds to 0.1 milligram equivalent per litre. Some workers on fresh waters, Birge and Juday (1911) for example, consider water as acid if it contains more carbon dioxide than that sufficient to convert the carbonate into bicarbonate, and titrate back to a pink with phenolphthalein. Their acid water is, however, still alkaline to methyl orange.

scholarly journals CAN CARBON DIOXIDE IN SEA WATER BE DIRECTLY DETERMINED BY TITRATION?

1916 ◽  
Vol 24 (1) ◽  
pp. 31-35
Author(s):  
Sergius Morgulis ◽  
Everett W. Fuller
Keyword(s):  
Carbon Dioxide ◽  
Sea Water

Carbon dioxide storage in Dead Sea water

2021 ◽  
Author(s):  
Mohammad Al-Harahsheh ◽  
Raghad Al-Khatib ◽  
Aiman Al-Rawajfeh
Keyword(s):  
Carbon Dioxide ◽  
Sea Water ◽  
Dead Sea ◽  
Carbon Dioxide Storage

scholarly journals Single-nucleus RNA-seq and FISH identify coordinated transcriptional activity in mammalian myofibers

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthieu Dos Santos ◽  
Stéphanie Backer ◽  
Benjamin Saintpierre ◽  
Brigitte Izac ◽  
Muriel Andrieu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Transcription Factors ◽  
Neuromuscular Junction ◽  
Heavy Chain ◽  
Transcriptional Activity ◽  
Rna Seq ◽  
Hybrid Fibers ◽  
Adult Mice ◽  
Single Nucleus

Abstract Skeletal muscle fibers are large syncytia but it is currently unknown whether gene expression is coordinately regulated in their numerous nuclei. Here we show by snRNA-seq and snATAC-seq that slow, fast, myotendinous and neuromuscular junction myonuclei each have different transcriptional programs, associated with distinct chromatin states and combinations of transcription factors. In adult mice, identified myofiber types predominantly express either a slow or one of the three fast isoforms of Myosin heavy chain (MYH) proteins, while a small number of hybrid fibers can express more than one MYH. By snRNA-seq and FISH, we show that the majority of myonuclei within a myofiber are synchronized, coordinately expressing only one fast Myh isoform with a preferential panel of muscle-specific genes. Importantly, this coordination of expression occurs early during post-natal development and depends on innervation. These findings highlight a previously undefined mechanism of coordination of gene expression in a syncytium.

Low-Fluence Laser Induced Fragmentation and Desorption of 3,4,9,10-Perylenetetracarboxylic Dianhydride (PTCDA) Thin Film

2013 ◽  
Vol 543 ◽  
pp. 30-34 ◽  
Author(s):  
Aljona Ramonova ◽  
Tengiz Butkhuzi ◽  
Viktorija Abaeva ◽  
I.V. Tvauri ◽  
Soslan Khubezhov ◽  
...  
Keyword(s):  
Thin Film ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Kinetic Energy ◽  
Atomic Oxygen ◽  
Laser Light ◽  
Pulsed Laser ◽  
Molecular Fragmentation ◽  
Irradiation Pulse ◽  
Main Effect

Laser-induced fragmentation and desorption of fragments of PTCDA films vacuum-deposited on GaAs (100) substrate has been studied by time-of-flight (TOF) mass spectroscopy. The main effect caused by pulsed laser light irradiation (pulse duration: 10 ns, photon energy: 2.34 eV and laser fluence ranging from 0.5 to 7 mJ/cm2) is PTCDA molecular fragmentation and desorption of the fragments formed, whereas no desorption of intact PTCDA molecule was detected. Fragments formed are perylene core C20H8, its half C10H4, carbon dioxide, carbon monoxide and atomic oxygen. All desorbing fragments have essentially different kinetic energy. The mechanism of photoinduced molecular fragmentation and desorption is discussed.

scholarly journals The Hydrogen-ion Concentration of Sea Water

Nature ◽  
1923 ◽  
Vol 111 (2778) ◽  
pp. 132-133
Author(s):  
J. J.
Keyword(s):  
Sea Water ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration
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