scholarly journals MICRURGICAL STUDIES IN CELL PHYSIOLOGY

1926 ◽  
Vol 10 (1) ◽  
pp. 9-21 ◽  
Author(s):  
Paul Reznikoff
Keyword(s):  
Heavy Metals ◽  
Metal Cation ◽  
Surface Membrane ◽  
The Other ◽  
Contractile Vacuole ◽  
Toxic Action ◽  
Cell Physiology ◽  
Relative Toxicity ◽  
A Cell

I. Plasmalemma. 1. The order of toxicity of the salts used in these experiments on the surface membrane of a cell, taking as a criterion viability of amebæ immersed in solutions for 1 day, is HgCl2, FeCl3> AlCl3> CuCl2> PbCl2> FeCl2. Using viability for 5 days as a criterion, the order of toxicity is PbCl2> CuCl2> HgCl2> AlCl3> FeCl3> FeCl2. 2. The rate of toxicity is in the order FeCl3> HgCl2> AlCl3> FeCl2> CuCl2> PbCl2. 3. The ability of amebæ to recover from a marked tear of the plasmalemma in the solutions of the salts occurred in the following order: AlCl3> PbCl2> FeCl2> CuCl2> FeCl3> HgCl2. II. Internal Protoplasm. 4. The relative toxicity of the salts on the internal protoplasm, judged by the recovery of the amebæ from large injections and the range over which these salts can cause coagulation of the internal protoplasm, is in the following order: PbCl2> CuCl2> FeCl3> HgCl2> FeCl2> AlCl3. 5. AlCl3 in concentrations between M/32 and M/250 causes a marked temporary enlargement of the contractile vacuole. FeCl2, FeCl3, and CuCl3 produce a slight enlargement of the vacuole. 6. PbCl2, in concentrations used in these experiments, appears to form a different type of combination with the internal protoplasm than do the other salts. III. Permeability. 7. Using the similarity in appearance of the internal protoplasm after injection and after immersion to indicate that the surface is permeable to a substance in which the ameba is immersed, it is concluded that AlCl3 can easily penetrate the intact plasmalemma. CuCl2 also seems to have some penetrating power. None of the other salts studied give visible internal evidence of penetrability into the ameba. IV. Toxicity. 8. The toxic action of the chlorides of the heavy metals used in these experiments, and of aluminum, is exerted principally upon the surface of the cell and is due not only to the action of the metal cation but also to acid which is produced by hydrolysis.

scholarly journals THE EFFECTS OF CERTAIN HEAVY METALS ON RESPIRATION

1926 ◽  
Vol 9 (4) ◽  
pp. 575-601 ◽  
Author(s):  
S. F. Cook
Keyword(s):  
Heavy Metals ◽  
Carbon Dioxide ◽  
Aspergillus Niger ◽  
Temperature Coefficient ◽  
Active Compound ◽  
Carbon Dioxide Production ◽  
Experimental Results ◽  
Toxic Action ◽  
Chemical Combination ◽  
A Cell

1. The effect of the heavy metals on the respiration of Aspergillus niger is to cause the rate of carbon dioxide production to decrease from the first or to increase and subsequently diminish. 2. The speed of the toxic action varies as a constant power of the concentration. 3. The temperature coefficient of the toxic action is between 1.5 and 2. 4. An hypothesis is advanced to account for the action of the heavy metals, by means of which the experimental results may be accounted for. It is assumed that the metal is activated by a chemical combination with a cell constituent. This active compound alters the velocity constants of the normal respiratory reactions, and thus causes the observed changes in the rate of carbon dioxide production.

scholarly journals MICRURGICAL STUDIES IN CELL PHYSIOLOGY

1926 ◽  
Vol 8 (4) ◽  
pp. 369-401 ◽  
Author(s):  
Robert Chambers ◽  
Paul Reznikoff
Keyword(s):  
Surface Membrane ◽  
Surrounding Medium ◽  
Lethal Effect ◽  
Great Difficulty ◽  
Amoeba Proteus ◽  
Cell Physiology ◽  
Appreciable Effect ◽  
Disruptive Effect ◽  
Liquid Sphere ◽  
A Cell

By means of micro-dissection and injection Amœba proteus was treated with the chlorides of Na, K, Ca, and Mg alone, in combination, and with variations of pH. I. The Plasmalemma. 1. NaCl weakens and disrupts the surface membrane of the ameba. Tearing the membrane accelerates the disruption which spreads rapidly from the site of the tear. KCl has no disruptive effect on the membrane but renders it adhesive. 2. MgCl2 and CaCl2 have no appreciable effect on the integrity of the surface membrane of the ameba when applied on the outside. No spread of disruption occurs when the membrane is torn in these salts. When these salts are introduced into the ameba they render the pellicle of the involved region rigid. II. The Internal Protoplasm. 3. Injected water either diffuses through the protoplasm or becomes localized in a hyaline blister. Large amounts when rapidly injected produce a "rushing effect". 4. HCl at pH 1.8 solidifies the internal protoplasm and at pH 2.2 causes solidification only after several successive injections. The effect of the subsequent injections may be due to the neutralization of the cell-buffers by the first injection. 5. NaCl and KCl increase the fluidity of the internal protoplasm and induce quiescence. 6. CaCl2 and MgCl2 to a lesser extent solidify the internal protoplasm. With CaCl2 the solidification tends to be localized. With MgCl2 it tends to spread. The injection of CaCl2 accelerates movement in the regions not solidified whereas the injection of MgCl2 induces quiescence. III. Pinching-Off Reaction. 7. A hyaline blister produced by the injection of water may be pinched off. The pinched-off blister is a liquid sphere surrounded by a pellicle. 8. Pinching off always takes place with injections of HCl when the injected region is solidified. 9. The injection of CaCl2 usually results in the pinching off of the portion solidified. The rate of pinching off varies with the concentration of the salt. The injection of MgCl2 does not cause pinching off. IV. Reparability of Torn Surfaces. 10. The repair of a torn surface takes place readily in distilled water. In the different salt solutions, reparability varies specifically with each salt, with the concentration of the salt, and with the extent of the tear. In NaCl and in KCl repair occurs less readily than in water. In MgCl2 repair takes place with great difficulty. In CaCl2 a proper estimate of the process of repair is complicated by the pinching-off phenomenon. However, CaCl2 is the only salt found to increase the mobility of the plasmalemma, and this presumably enhances its reparability. 11. The repair of the surface is probably a function of the internal protoplasm and depends upon an interaction of the protoplasm with the surrounding medium. V. Permeability. 12. NaCl and KCl readily penetrate the ameba from the exterior. CaCl2 and MgCl2 do not. 13. All four salts when injected into an ameba readily diffuse through the internal protoplasm. In the case of CaCl2 the diffusion may be arrested by the pinching-off process. VI. Toxicity. 14. NaCl and KCl are more toxic to the exterior of the cell than to the interior, and the reverse is true for CaCl2 and MgCl2. 15. The relative non-toxicity of injected NaCl to the interior of the ameba is not necessarily due to its diffusion outward from the cell. 16. HCl is much more toxic to the exterior of a cell than to the interior; at pH 5.5 it is toxic to the surface whereas at pH 2.5 it is not toxic to the interior. NaOH to pH 9.8 is not toxic either to the surface or to the interior. VII. Antagonism. 17. The toxic effects of NaCl and of KCl on the exterior of the cell can be antagonized by CaCl2 and this antagonism occurs at the surface. Although the lethal effect of NaCl is thus antagonized, NaCl still penetrates but at a slower rate than if the ameba were immersed in a solution of this salt alone. 18. NaCl and HCl are mutually antagonistic in the interior of the ameba. No antagonism between the salts and HCl was found on the exterior of the ameba. No antagonism between the salts and NaOH was found on the interior or exterior of the ameba. 19. The pinching-off phenomenon can be antagonized by NaCl or by KCl, and the rate of the retardation of the pinching-off process varies with the concentration of the antagonizing salt. 20. The prevention of repair of a torn membrane by toxic solutions of NaCl or KCl can be antagonized by CaCl2. These experiments show directly the marked difference between the interior and the exterior of the cell in their behavior toward the chlorides of Na, K, Ca, and Mg.

scholarly journals MICRURGICAL STUDIES IN CELL PHYSIOLOGY

1928 ◽  
Vol 11 (3) ◽  
pp. 221-232 ◽  
Author(s):  
Paul Reznikoff
Keyword(s):  
Surface Membrane ◽  
Toxic Action ◽  
Cell Physiology ◽  
Better Than

I. The Plasmalemma. 1. On the plasmalemma of amebæ CaCl2 antagonizes the toxic action of LiCl better than it does NaCl, and still better than it does KCl. MgCl2 antagonizes the toxic action of NaCl better than it does LiCl and still better than it does KCl. 2. CaCl2 antagonizes the toxic action of LiCl and of KCl better than does MgCl2: MgCl2 antagonizes NaCl better than does CaCl2. II. The Internal Protoplasm. 3. The antagonizing efficiency of CaCl2 and of MgCl2 are highest against the toxic action of KCl on the internal protoplasm, less against that of NaCl, and least against that of LiCl. 4. CaCl2 antagonizes the toxic action of LiCl better than does MgCl2: MgCl2 antagonizes the toxic action of NaCl and of KCl better than does CaCl2. 5. LiCl antagonizes the toxic action of MgCl2 on the internal protoplasm more effectively than do NaCl or KCl, which have an equal antagonizing effect on the MgCl2 action. III. The Nature of Antagonism. 6. When the concentration of an antagonizing salt is increased to a toxic value, it acts synergistically with a toxic salt. 7. No case was found in which a potentially antagonistic salt abolishes the toxic action of a salt unless it is present at the site (surface or interior) of toxic action. 8. Antagonistic actions of the salts used in these experiments are of differing effectiveness on the internal protoplasm and on the surface membrane.

Assessment of micro and macro nutrients in poultry feeds available in Dhaka city, Bangladesh.

2017 ◽  
Vol 1 ◽  
pp. 264
Author(s):  
Md Didarul Islam ◽  
Ashiqur Rahaman ◽  
Fahmida Jannat
Keyword(s):  
Heavy Metals ◽  
Adverse Effect ◽  
The Other ◽  
Nutrient Level ◽  
Dhaka City ◽  
Toxic Heavy Metals ◽  
High Concentration ◽  
Low Concentration ◽  
Feed Formulation ◽  
Macro Nutrients

This study was based on to determine the concentration of macro and micro nutrients as well as toxic and nontoxic heavy metals present in the chicken feed available in Dhaka city of Bangladesh. All macro nutrients, if present in the feed at high concentration have some adverse effect, at the same time if this nutrient present in the feed at low concentration this have some adverse effect too. So that this nutrient level should be maintained at a marginal level. On the other side toxic heavy metals if present in the feed at very low concentration those can contaminate the total environment of the ecosystem. In this study six brand samples (starter, grower, finisher and layer) which was collected from different renowned chicken feed formulation industry in Bangladesh. Those samples were prepared for analysis by wet ashing and then metals were determined by Atomic Absorption Spectroscopy. It was found that 27.7 to 68.4, 57.3 to 121.9, 0.21 to 4.1, 0.32 to 2.1, 0.11 to 1.58, 0.28 to 2.11 and 0.28 to 1.78 for zinc, iron, copper, mercury, cadmium, nickel and cobalt respectively. It was found that essential macro and micro nutrients were present in the feed in low concentration on the other side mercury was present in high concentration in the feed samples.

scholarly journals Innovative Ultrasound-Assisted Approaches towards Reduction of Heavy Metals and Iodine in Macroalgal Biomass

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 649
Author(s):  
Estefanía Noriega-Fernández ◽  
Izumi Sone ◽  
Leire Astráin-Redín ◽  
Leena Prabhu ◽  
Morten Sivertsvik ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Dry Weight ◽  
The Other ◽  
Laminaria Hyperborea ◽  
Other Hand ◽  
Macroalgal Biomass ◽  
Ultrasound Assisted ◽  
I 31

The aim of this work was to evaluate the potential of ultrasound (US), alone or in combination with mild heating and/or EDTA towards reduction of As, Cd, I, and Hg content of Laminaria hyperborea. Concentrations of As, Cd, I, and Hg of 56.29, 0.596, 7340, and <0.01 mg kg−1 of dry weight, respectively, were found in L. hyperborea blades. Treatment with US at 50 °C increased approx. 2-fold the amount of As released, although did not affect significantly the content of Cd or I, as compared to control (no US) samples. Reducing the temperature to 8 °C significantly decreased the effect of US, but heating at 80 °C did not cause a significant effect as compared to treatments at 50 °C. On the other hand, treatment with 0.1 N EDTA at 50 °C enhanced the percentage of Cd released by approximately 7-fold, regardless of sonication. In the present work, the combination of US and EDTA at 50 °C for 5 min led to a significant reduction of the As (32%), Cd (52%) and I (31%) content in L. hyperborea, thus improving the product’s safety for consumers.

Relationship between the membrane potential of the contractile vacuole complex and its osmoregulatory activity inParamecium multimicronucleatum

2002 ◽  
Vol 205 (20) ◽  
pp. 3261-3270 ◽  
Author(s):  
Heidi K. Grønlien ◽  
Christian Stock ◽  
Marilynn S. Aihara ◽  
Richard D. Allen ◽  
Yutaka Naitoh
Keyword(s):  
Reference Electrode ◽  
Maximum Level ◽  
The Other ◽  
Contractile Vacuole ◽  
Hypertonic Solution ◽  
Hypotonic Solution ◽  
Atpase Inhibitor ◽  
Filling Phase ◽  
High Level

SUMMARYThe electric potential of the contractile vacuole (CV) of Paramecium multimicronucleatum was measured in situ using microelectrodes,one placed in the CV and the other (reference electrode) in the cytosol of a living cell. The CV potential in a mechanically compressed cell increased in a stepwise manner to a maximal value (approximately 80 mV) early in the fluid-filling phase. This stepwise change was caused by the consecutive reattachment to the CV of the radial arms, where the electrogenic sites are located. The current generated by a single arm was approximately 1.3×10-10 A. When cells adapted to a hypotonic solution were exposed to a hypertonic solution, the rate of fluid segregation, RCVC, in the contractile vacuole complex (CVC) diminished at the same time as immunological labelling for V-ATPase disappeared from the radial arms. When the cells were re-exposed to the previous hypotonic solution, the CV potential, which had presumably dropped to near zero after the cell's exposure to the hypertonic solution, gradually returned to its maximum level. This increase in the CV potential occurred in parallel with the recovery of immunological labelling for V-ATPase in the radial arm and the resumption of RCVC or fluid segregation. Concanamycin B, a potent V-ATPase inhibitor, brought about significant decreases in both the CV potential and RCVC. We confirm that (i) the electrogenic site of the radial arm is situated in the decorated spongiome, and (ii) the V-ATPase in the decorated spongiome is electrogenic and is necessary for fluid segregation in the CVC. The CV potential remained at a constant high level(approximately 80 mV), whereas RCVC varied between cells depending on the osmolarity of the adaptation solution. Moreover, the CV potential did not change even though RCVC increased when cells adapted to one osmolarity were exposed to a lower osmolarity, implying that RCVC is not directly correlated with the number of functional V-ATPase complexes present in the CVC.

Removal of Heavy Metals from Industrial Effluent by Crossflow Microfiltration

1992 ◽  
Vol 25 (10) ◽  
pp. 55-67 ◽  
Author(s):  
R. C. Squires
Keyword(s):  
Heavy Metals ◽  
Pilot Trial ◽  
Industrial Effluent ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Sodium Sulphate ◽  
The Other ◽  
Operating Costs ◽  
Treated Effluent ◽  
Crossflow Microfiltration

The performance of Exxflow, a patented form of crossflow microfiltration, treating industrial wastewaters containing mixed heavy metals discharged by two types of industry is quantified and compared with the traditional technologies used for such treatment. Pilot trial results using Exxflow are shown and compared to the performance of the full scale plants now operating on these effluents. The operating costs of the Exxflow process are estimated for the two plants. One of which has been operating for 18 months and the other about 4 months. The Exxflow process is described and improvements which are being developed to lower the operating costs are presented. It is shown that industrial effluents containing mixed heavy metals are very effectively treated by the Exxflow process and since the installation of the plants the treated effluent has been of a quality suitable for discharge to the River Thames in one case and to a sewage treatment plant in the other. Unlike other processes, Exxflow has shown that it can successfully treat effluent containing mixed metals and that removal of antimony from mixed metal waste waters is affected by the concentration of sodium sulphate in the wastewater.

scholarly journals Repression of differentiation genes by Hes transcription factors fuels neural tumour growth in Drosophila

2021 ◽  
Author(s):  
Chrysanthi Voutyraki ◽  
Alexandros Choromidis ◽  
Vasiliki Theodorou ◽  
Christina Efraimoglou ◽  
Gerasimos Anagnostopoulos ◽  
...  
Keyword(s):  
Stem Cell ◽  
Transcription Factors ◽  
Notch Signaling ◽  
Tumour Growth ◽  
Metabolic Reprogramming ◽  
Cell Physiology ◽  
Malignant Tumours ◽  
Rna Profiling ◽  
A Cell

Background: Neural stem cells (NSC) in divide asymmetrically to generate a cell that retains stem cell identity and another that is routed to differentiation. Prolonged mitotic activity of the NSCs gives rise to the plethora of neurons and glial cells that wire the brain and nerve cord. Genetic insults, such as excess of Notch signaling, perturb the normal NSC proliferation programs and trigger the formation of NSC hyperplasias, that can later progress to malignancies. Hes proteins are crucial mediators of Notch signaling and in the NSC context they act by repressing a cohort of early pro-differentiation transcription factors. Downregulation of these pro-differentiation factors makes NSC progeny cells susceptible to adopting an aberrant stem cell program. We have recently shown that Hes overexpression in Drosophila leads to NSC hyperplasias that progress to malignant tumours after allografting to adult hosts. Methods: We have combined genetic analysis, tissue allografting and transcriptomic approaches to address the role of Hes genes in NSC malignant transformation. Results: We show that the E(spl) genes are important mediators in the progression of Notch hyperplasias to malignancy, since allografts lacking the E(spl) genes grow much slower. We further present RNA profiling of Hes-induced tumours at two different stages after allografting. We find that the same cohort of differentiation-promoting transcription factors that are repressed in the primary hyperplasias continue to be downregulated after transplantation. This is accompanied by an upregulation of stress-response genes and metabolic reprogramming. Conclusions: The combination of dedifferentiation and cell physiology changes most likely drive tumour growth.

scholarly journals Numerical Simulation of a Textured and Untextured Photovoltaic Solar Cell: Comparative study

2021 ◽  
Vol 03 (01) ◽  
pp. 104-114
Author(s):  
Karim Salim ◽  
◽  
M.N Amroun ◽  
K Sahraoui ◽  
W Azzoui ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Solar Cell ◽  
Comparative Study ◽  
Silicon Solar Cell ◽  
The Other ◽  
Surface Parameters ◽  
Cell Efficiency ◽  
Photovoltaic Solar Cell ◽  
A Cell

Increasing the efficiency of solar cells relies on the surface of the solar cell. In this work, we simulated a textured silicon solar cell. This simulation allowed us to predict the values of the surface parameters such as the angle and depth between the pyramids for an optimal photovoltaic conversion where we found the Icc: 1.783 (A) and Vco: 0.551 (V) with a cell efficiency of about 13.56%. On the other hand, we performed another simulation of a non-textured solar cell to compare our values and found Icc: 1.623 (A) and Vco: 0.556 (V) with an efficiency of about 12.76%.

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