Iron Metabolism in Mytilus Edulis 1. Variation in Total Content and Distribution

1967 ◽  
Vol 47 (3) ◽  
pp. 597-606 ◽  
Author(s):  
D. J. Hobden
Keyword(s):  
Mytilus Edulis ◽  
Iron Content ◽  
Sea Water ◽  
Total Content ◽  
Gut Contents ◽  
Order Of Magnitude ◽  
Wet Weight ◽  
The Mean ◽  
Trace Element Metabolism ◽  
Living Organisms

The iron content of fresh Mytilus edulis L. from Southampton is usually 20–40 μg/g wet weight after the animals have eliminated their gut contents. In spring some animals have much higher iron contents, sometimes in excess of 100 μg/g. The much higher values reported by some authors are probably erroneous.Prolonged starvation in sea water of low iron content will not reduce the mean iron content of the animals below 20–25 μg/g. This represents a permanent store. Higher values are produced by a temporary store that is fairly rapidly lost on starvation.The highest iron concentrations are usually in the digestive gland, which contains the major part of the temporary store, much of which can be regarded as particles being subjected to the digestive processes.Only iron in the temporary store could be demonstrated by histochemical techniques.INTRODUCTIONThe trace element metabolism of Vertebrates, particularly Mammals has been reviewed by Bothwell & Finch (1962); and Vinogradov (1953) has made a comprehensive review of the elementary chemical composition of living organisms. With notable exceptions, such as the copper in haemocyanin, the trace elements discovered in many invertebrates have no known function. The reported values for many elements differ considerably, depending on the author and the techniques used. In general, despite a number of errors in the values quoted, Vinogradov's data establish at least the order of magnitude of many elements in a variety of animals. Some of these elements occur in greater amounts than would be expected if they were not of metabolic significance. One example, namely iron in Mytilus edulis L., was selected for investigation.

scholarly journals POTASSIUM MOVEMENT IN RELATION TO NERVE ACTIVITY

1951 ◽  
Vol 34 (6) ◽  
pp. 795-807 ◽  
Author(s):  
Abraham M. Shanes
Keyword(s):  
Time Constant ◽  
Calcium Concentration ◽  
Sea Water ◽  
Calcium Content ◽  
Squid Axon ◽  
Nerve Activity ◽  
Potassium Accumulation ◽  
Low Concentrations ◽  
Order Of Magnitude ◽  
Wet Weight

The depolarization of crab nerve during repetitive stimulation is unaffected by the presence of glucose or by an increase in the calcium content of the medium. It is increased in both amplitude and rate by veratrine; in the presence of this alkaloid mixture the rate but not the magnitude of the depolarization is increased by an elevation in the calcium concentration. Repolarization following stimulation is unaltered by glucose and accelerated by a greater calcium concentration. Veratrine increases both the amplitude and the time constant of repolarization; its effect on the time constant is counteracted by an elevation of the calcium in the medium. Potassium released during stimulation and its reabsorption following activity have been observed by analyses of small volumes of sea water in contact with crab nerve. Under the conditions employed 3 x 10–8 µM potassium is liberated per impulse per gm. wet weight of nerve. This loss is increased by low concentrations of veratrine, which also increase the amount reabsorbed during recovery. The depletion of potassium from the medium is appreciably less if the potassium previously released during activity has not been removed. Inexcitability resulting from anoxia can be washed away with oxygen-free solution—rapidly and completely in the case of the squid axon, slowly and incompletely in crab nerve. The potassium shifts are in the proper direction and of the correct order of magnitude to account for the negative and positive after-potentials in terms of potassium accumulation or depletion in the extracellular space.

Force Exerted by a Single Cilium of Mytilus Edulis

1962 ◽  
Vol 39 (2) ◽  
pp. 307-317
Author(s):  
MITSUKI YONEDA
Keyword(s):  
Angular Velocity ◽  
Mytilus Edulis ◽  
Sea Urchin ◽  
Model Experiment ◽  
Sea Water ◽  
Free Motion ◽  
A Value ◽  
Angular Velocities ◽  
Order Of Magnitude ◽  
Single Subunit

1. Angular velocities of the large abfrontal cilium of Mytilus beating in media of various viscosities were measured. 2. An equation for the force produced by a single cilium in free motion was derived by hydrodynamical methods. Expressing the force in terms of torque referred to the base of the cilium: Torque = angular velocity x viscosity x (length of the cilium)3 x constant. The constant appropriate to the effective stroke of the large abfrontal cilium was found by a model experiment to have a value of 1.1 . 3. The torque exerted by the cilium in normal sea water was 2 x 10-8 dyne.cm. Increase of viscosity resulted in increase in the torque. 4. The maximum power developed by the cilium was calculated to be 1.2 x 10-6 erg/sec. Assuming that a single cilium is made up of 20 subunits, the power developed by a single subunit is 6 x 10-8 erg/sec., which is of the same order of magnitude as the power developed by a single spermatozoon of a sea urchin (Carlson, 1959).

scholarly journals I. Tidal friction in the Irish Sea

1920 ◽  
Vol 220 (571-581) ◽  
pp. 1-33 ◽  
Keyword(s):  
Sea Water ◽  
Irish Sea ◽  
Viscous Drag ◽  
Tidal Friction ◽  
Uneven Bottom ◽  
Dissipation Of Energy ◽  
Order Of Magnitude ◽  
The Subject ◽  
The Mean ◽  
The Irish Sea

The dissipation of energy in the tides has recently formed the subject of a paper by Mr. R. O. Street. In that paper it is assumed that the energy is dissipated by the viscous drag of layers of water which move parallel to the bottom of the sea. The assumption that tidal currents move in laminar motion is so opposed to ordinary observation of the surface of the sea in a tideway that I felt certain, on reading the paper, that if some other method could be found, which did not depend on any special assumptions as to the nature of the motion, it would be found that Mr. Street’s estimate of the dissipation is very much too small. This view is strengthened by the consideration that Reynolds criterion of stability would lead us to expect that eddies would form in any stream of sea-water flowing at a speed of 1 knot or more, when the depth is greater than some quantity of the order of magnitude of 1 or 2 cm. Since the mean depth of the Irish Sea is over 40 fathoms, mathematical considerations alone would lead us to suspect the existence of the eddies, which can in fact he seen marking the surface of the sea in places where the current runs exceptionally strongly, or over a particularly uneven bottom. Several of these places are marked as “ripples” on the chart of the Irish Sea, the sheet of water to which Mr. Street applied his calculations.

The Inorganic Composition of the Blood of Mytilus Edulis and Anodonta Cygnea

1954 ◽  
Vol 31 (3) ◽  
pp. 376-385
Author(s):  
W. T. W. POTTS
Keyword(s):  
Carbon Dioxide ◽  
Mytilus Edulis ◽  
Sea Water ◽  
Total Concentration ◽  
Total Carbon ◽  
Anodonta Cygnea ◽  
Ionic Solutions ◽  
Order Of Magnitude ◽  
Inorganic Composition ◽  
Inorganic Constituents

1. Analyses have been made of the inorganic constituents of the blood of Mytilus edulis and Anodonta cygnea. 2. Mytilus blood resembles sea water in total concentration and composition, but has greater concentrations of calcium, potassium and total carbon dioxide. 3. Anodonta blood has a very low total concentration of solutes, but the concentrations of calcium and carbon dioxide are of the same order of magnitude as the concentrations in Mytilus blood. 4. This is discussed with reference to solubility of calcium carbonate in ionic solutions, and it is concluded that the blood of both animals is saturated with respect to aragonite.

Localization of calcium and zinc in the sperm storage tubules of chicken, quail and turkey using X-ray microanalysis

Reproduction ◽  
2000 ◽  
pp. 331-336 ◽  
Author(s):  
L Holm ◽  
H Ekwall ◽  
GJ Wishart ◽  
Y Ridderstrale
Keyword(s):  
Calcium Concentration ◽  
Sperm Storage ◽  
X Ray ◽  
Elemental Concentrations ◽  
Low Concentrations ◽  
Intracellular Content ◽  
Wet Weight ◽  
The Mean ◽  
Sperm Storage Tubules ◽  
Scanning Electron

Sperm storage tubules from the utero-vaginal junction of chickens, quails and turkeys were analysed for calcium and zinc using X-ray microanalysis of ultra-rapidly frozen tissue in a scanning electron microscope. This technique enabled the tubular fluid surrounding the stored spermatozoa and the intracellular content of the cells of the sperm storage tubules to be analysed separately and, by using standards with known concentrations, their elemental concentrations were estimated. The mean (+/- SEM) concentration of calcium in the tubular fluid from chickens, quails and turkeys was 17 +/- 3, 19 +/- 3 and 17 +/- 4 mmol kg(-1) wet weight, respectively. The intracellular calcium concentration of the cells of the tubules did not differ significantly from these values and was also similar in the mucosal epithelial cells of the utero-vaginal junction. Zinc was localized in the cells of turkey sperm storage tubules and tubular fluid, but at low concentrations. No zinc could be detected in corresponding structures from chickens and quails. The concentration of calcium in the tubular fluid is within the range known to inhibit the motility of spermatozoa, supporting this function for calcium during storage. Zinc is known to depress turkey sperm metabolism and it may also be involved in inducing quiescence of spermatozoa during storage in this species.

scholarly journals The Effect of Granular Activated Carbon and Biochar on the Availability of Cu and Zn to Hordeum sativum Distichum in Contaminated Soil

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 841
Author(s):  
Marina Burachevskaya ◽  
Saglara Mandzhieva ◽  
Tatiana Bauer ◽  
Tatiana Minkina ◽  
Vishnu Rajput ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Activated Carbon ◽  
Spring Barley ◽  
Granular Activated Carbon ◽  
Total Content ◽  
Metal Compounds ◽  
Significant Difference ◽  
High Sorption ◽  
Living Organisms ◽  
Cu And Zn

The presence of heavy metals in the soil could impose serious problems on soil-plant systems due to the accumulation of heavy metals in plants. Even vital elements such as Cu and Zn have a toxic effect in the case of excessive intake by living organisms. The present work aimed to investigate the content of loosely bound (exchangeable, complexed, and specifically sorbed) compounds of Cu and Zn and their availability to spring barley (Hordeum sativum distichum) in contaminated Haplic Chernozem soil under the conditions of a model experiment (five approximate permissible concentrations (APC) and 10 APC of metal). Changes in the bioavailability of the metals upon application of carbon sorbents were observed. An increase in loosely bound metal compounds has been shown under conditions of soil contamination with metals (up to 57% of the total content). The increase in the availability of Cu in the soil was mainly due to the formation of complexed metal forms with organic matter (up to 17%). The availability of Zn was found to be associated with an increase in exchangeable (up to 21%) and specifically sorbed compounds (up to 27%). Granular activated carbon (GAC) and biochar have high sorption properties. A decrease in the content of loosely bound compounds of metals was established, especially in the most mobile forms such as exchangeable and complexed forms. The introduction of sorbents into the soil opened up a new venue for binding heavy metals in situ, eventually leading to a decrease in their bioavailability. The inactivation of Cu and Zn in the soil upon the application of sorbents led to a decrease in metal absorption by spring barley. The highest efficiency of biochar application was established at a dose of 2.5% and 5% in soil contaminations of 5 APC and 10 APC of Cu or Zn. The efficiency of the use of sorbents was more influenced by the dose of application than by the type of sorbent. There was no significant difference between biochar and GAC. Stabilization and inactivation of metals may improve soil fertility and plant growth.

scholarly journals Relaxation Times in Strictly Disk Systems

1971 ◽  
Vol 10 ◽  
pp. 15-19
Author(s):  
George B. Rybicki
Keyword(s):  
Numerical Experiments ◽  
Relaxation Times ◽  
Galactic Structure ◽  
Large Numbers ◽  
Order Of Magnitude ◽  
Vlasov Limit ◽  
The Mean ◽  
Gravitating Systems

AbstractIt is shown that the time of relaxation by particle encounters of self-gravitating systems in the plane interacting by 1/r2 forces is of the same order of magnitude as the mean orbit time. Therefore such a system does not have a Vlasov limit for large numbers of particles, unless appeal is made to some non-zero thickness of the disk. The relevance of this result to numerical experiments on galactic structure is discussed.

Cadmium concentrations in kidneys of sheep and cattle in Western Australia. 1. Regional distribution

1994 ◽  
Vol 45 (4) ◽  
pp. 851 ◽  
Author(s):  
PW Morcombe ◽  
DS Petterson ◽  
HG Masters ◽  
PJ Ross ◽  
JR Edwards
Keyword(s):  
Western Australia ◽  
Geometric Mean ◽  
Regional Distribution ◽  
Adult Cattle ◽  
Agricultural Region ◽  
Wet Weight ◽  
The Mean ◽  
Winter Annual ◽  
Rate Of Accumulation ◽  
Cattle And Sheep

A sample of 4973 kidneys from sheep stratified by age and shire of origin within the Agricultural Region of Western Australia, was analysed for cadmium (Cd) content during the period August 1989 to April 1991. The geometric mean Cd concentration in the kidney of hogget ewes was 0.9 mg/kg, in 4-tooth ewes 1.47 mg/kg and in adult ewes 3.34 mg/kg on a wet weight basis. The mean Cd concentrations of either ewe or hogget flocks from different Divisions of the Agricultural Region did not differ from each other. The annual increase in Cd concentration of kidney from hogget sheep was estimated to be 0-65 mg/kg. The rate of accumulation of Cd in kidney from cattle and sheep grazing the same properties was similar. Kidneys from a sample of 354 adult cattle from the Kimberley Region and 483 aged sheep from the Pastoral Region, both areas of unimproved rangelands, had geometric mean Cd concentrations of 0.15 mg/kg and 0-31 mg/kg respectively. A higher Cd concentration in flocks from the divisions adjacent to the Agricultural Region may have resulted from the establishment of some volunteer species of winter annual pastures in the rangeland.

scholarly journals Using the SWEPT Methodology for a Preliminary Wind Potential Estimation

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Jean-Luc Menet
Keyword(s):  
Wind Turbine ◽  
Characteristic Curve ◽  
Rayleigh Distribution ◽  
Mean Velocity ◽  
Technical Data ◽  
Wind Potential ◽  
Order Of Magnitude ◽  
General Data ◽  
The Mean ◽  
A Site

The implantation of wind turbines generally follows a wind potential study which is made using specific numerical tools; the generated expenses are only acceptable for great projects. The purpose of the present paper is to propose a simplified methodology for the evaluation of the wind potential, following three successive steps for the determination of (i) the mean velocity, either directly or by the use of the most occurrence velocity (MOV); (ii) the velocity distribution coming from the single knowledge of the mean velocity by the use of a Rayleigh distribution and a Davenport-Harris law; (iii) an appropriate approximation of the characteristic curve of the turbine, coming from only two technical data. These last two steps allow calculating directly the electric delivered energy for the considered wind turbine. This methodology, called the SWEPT approach, can be easily implemented in a single worksheet. The results returned by the SWEPT tool are of the same order of magnitude than those given by the classical commercial tools. Moreover, everybody, even a “neophyte,” can use this methodology to obtain a first estimation of the wind potential of a site considering a given wind turbine, on the basis of very few general data.

Infrared spectra, rotational correlation functions, and intermolecular mean squared torques in compressed gaseous methane

1968 ◽  
Vol 46 (11) ◽  
pp. 1331-1340 ◽  
Author(s):  
R. L. Armstrong ◽  
S. M. Blumenfeld ◽  
C. G. Gray
Keyword(s):  
Correlation Functions ◽  
Theoretical Calculations ◽  
Dominant Contribution ◽  
Dispersion Interactions ◽  
Fundamental Vibration ◽  
Order Of Magnitude ◽  
The Mean ◽  
Vibration Rotation ◽  
Experimental Values ◽  
Rotational Correlation

Extensive measurements of the methane ν3 and ν4 fundamental vibration–rotation bands in CH4–He mixtures and the ν3 band in CH4–He, CH4–N2, and CD4–He mixtures have been carried out in infrared absorption at 295 °K to pressures of 3000 atm. Some profiles of the ν3 band in CH4–Ar mixtures and in pure CH4 have also been obtained. Rotational correlation functions, band moments, and intermolecular mean squared torques have been determined from the ν3 band profiles. Theoretical calculations of the mean squared torque due to anisotropic multipolar, induction and dispersion interactions have been carried out. The theoretical and experimental torques are in order-of-magnitude agreement for the CH4–N2 and CH4–CH4 systems; for CH4–He, CD4–He, and CH4–Ar the theoretical values are two to three orders of magnitude too small to account for the experimental values, indicating that in these cases the dominant contribution to the torques is given by the anisotropic overlap forces.

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